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LiFePO 4 /Very-few-layer-graphene (LFP/VFLG) composites have been prepared using the sol-gel method for lithium-ion battery cathode. VFLG dominated by 1∼3 layers was obtained from an economical and environmentally benign process. Structural properties of LFP/VFLG composites were studied using Fourier-transform infrared spectra (FTIR) spectroscopy, X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy, while the electrochemical performance was measured using galvanostatic discharge, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) tests. The FTIR analysis confirmed that incorporating VFLG neither affected the chemical structure of LiFePO 4 nor initiated any side reactions during the LiFePO 4 formation reaction. The XRD results showed that LFP/VFLG composites had better lattice parameters, crystallinity, and phase purity than LiFePO 4 without VFLG addition. The Raman spectroscopy analysis indicated that LFP/VFLG composites had a lower disorder in the carbon arrangement. HRTEM results indicated that a VFLG was successfully wrapped around the LFP particle offers a versatile way to enhanced electrochemical performance of LFP/VFLG composites. The galvanostatic discharge profiles showed an enhancing specific discharge capacity of up to 58.3% after incorporating VFLG. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests revealed that LFP/VFLG delivered small polarization, low inner resistance, high electrochemical reaction reversibility, and high lithium-ion diffusion coefficient. VFLG is a promising additive to improve the structural and electrochemical properties of the LiFePO 4 cathode of lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Multiplex sampling, so far mainly used as a tool for S/N ratio improvement in spectroscopic applications and separation techniques, has been investigated here for its potential suitability for time-resolved monitoring where chromatograms of transient signals are recorded at intervals much shorter than the chromatographic runtime. Different designs of multiplex sample introduction were developed and utilized to analyze lithium-ion battery degradation products under normal or abuse conditions to achieve fast and efficient sample introduction. After comprehensive optimization, measurements were performed on two different GC systems, with either barrier discharge ionization detection (BID) or mass spectrometric detection (MS). Three different injector designs were examined, and modifications in the pertinent hardware components and operational conditions used. The shortest achievable sample introduction time was 50 ms with an interval of 6 s. Relative standard deviations were lower than 4% and 10% for the intra- and inter-day repeatability, respectively. The sample introduction system and column head pressure had to be carefully controlled, as this parameter most critically affects the amount of sample introduced and, thus, detector response. The newly developed sample introduction system was successfully used to monitor volatile degradation products of lithium-ion batteries and demonstrated concentration changes over the course of time of the degradation products (e.g., fluoroethane, acetaldehyde and ethane), as well as for solvents from the battery electrolyte like ethyl carbonate. [ABSTRACT FROM AUTHOR]

In the field of lithium-ion batteries, the challenges posed by the low melting point and inadequate wettability of conventional polyolefin separators have increased the focus on ceramic-coated separators. This study introduces a highly efficient and stable boehmite/polydopamine/polyethylene (AlOOH-PDA-PE) separator. It is crafted by covalently attaching functionalized nanosized boehmite (γ-AlOOH) whiskers onto polyethylene (PE) surfaces. The presence of a covalent bond increases the stability at the interface, while amino groups on the surface of the separator enhance the infiltration of the electrolyte and facilitate the diffusion of lithium ions. The PE-PDA-AlOOH separator, when used in lithium-ion batteries, achieves a discharge capacity of 126 mAh g−1 at 5 C and retains 97.1% capacity after 400 cycles, indicating superior cycling stability due to its covalently bonded ceramic surface. Thus, covalent interface modification is a promising strategy to prevent delamination of ceramic coatings in separators. [ABSTRACT FROM AUTHOR]

[Display omitted] Lithium cobalt phosphate (LiCoPO 4) has great potential to be developed as a cathode material for lithium-ion batteries (LIBs) due to its structural stability and higher voltage platform with a high theoretical energy density. However, the relatively low diffusion of lithium ions still needs to be improved. In this work, Fe and Zn co-doped LiCoPO 4 : LiCo 0.9-x Fe 0.1 Zn x PO 4 /C is utilized to enhance the battery performance of LiCoPO 4. The electrochemical properties of LiCo 0.85 Fe 0.1 Zn 0.05 PO 4 /C demonstrated an initial capacity of 118 mAh/g, with 93.4 % capacity retention at 1C after 100 cycles, and a good capacity of 87 mAh/g remained under a high current density of 10C. In addition, the diffusion rate of Li ions was investigated, proving the improvement of the materials with doping. The impedance results also showed a smaller resistance of the doped materials. Furthermore, operando X-ray diffraction displayed a good reversibility of the structural transformation, corresponding to cycling stability. This work provided studies of both the electrochemical properties and structural transformation of Fe and Zn co-doped LiCoPO 4 , which showed that 10 % Fe and 5 % Zn co-doping enhanced the electrochemical performance of LiCoPO 4 as a cathode material in LIBs. [ABSTRACT FROM AUTHOR]

Ru-doping introduces abundant oxygen defects and enlarges interlayer spacing, accelerating the ion and electron transmission of tetragonal phase Nb 2 O 5. [Display omitted] Breaking through the limitations of lithium-ion transmission is imperative for high-power rechargeable batteries. As a promising anode material for fast-charging lithium-ion batteries (LIBs), niobium pentoxide (Nb 2 O 5) has garnered considerable research attention due to its exceptional rate performance, stable lithium storage performance and high safety attributes. Nevertheless, the limited intrinsic conductivity of Nb 2 O 5 , coupled with its structural degradation during the cycling process, imposes constraints on its viability as a commercially viable electrode material. Herein, a ruthenium (Ru) doping method is employed to regulate the oxygen defects and the interlayer spacing of the tetragonal Nb 2 O 5 (M−Nb 2 O 5), offering superior reaction kinetics, higher stability for lithium storage sites and more unobstructed lithium-ion transport channels. Ru-doped Nb 2 O 5 (RNO) manifests excellent electrochemical properties, including remarkable rate capacity (166 mAh/g at 80C), reversible capacity (246.98 mAh/g at 0.5C), improved initial Coulombic efficiency (95.77 % compared to 81.44 % of the pure sample) and cycling stability (maintaining a capacity of 113.5 mAh/g at 10C for 2,000 cycles). The enhancement mechanism of Ru doping on the structural stability and ion transport kinetics in tetragonal Nb 2 O 5 is comprehensively elucidated through diverse electrochemical analyses and in-situ techniques. [ABSTRACT FROM AUTHOR]

High-entropy oxides (HEOs), as a new type of single-phase solid solution with a multi-component design, have shown great potential when they are used as anodes in lithium-ion batteries due to four kinds of effects (thermodynamic high-entropy effect, the structural lattice distortion effect, the kinetic slow diffusion effect, and the electrochemical "cocktail effect"), leading to excellent cycling stability. Although the number of articles on the study of HEO materials has increased significantly, the latest research progress in porous HEO materials in the lithium-ion battery field has not been systematically summarized. This review outlines the progress made in recent years in the design, synthesis, and characterization of porous HEOs and focuses on phase transitions during the cycling process, the role of individual elements, and the lithium storage mechanisms disclosed through some advanced characterization techniques. Finally, the future outlook of HEOs in the energy storage field is presented, providing some guidance for researchers to further improve the design of porous HEOs. [ABSTRACT FROM AUTHOR]

Transition metal nitride negative electrode materials with a high capacity and electronic conduction are still troubled by the large volume change in the discharging procedure and the low lithium ion diffusion rate. Synthesizing the composite material of F-doped Fe3N and an N-doped porous carbon framework will overcome the foregoing troubles and effectuate a preeminent electrochemical performance. In this study, we created a simple route to obtain the composite of F-doped Fe3N nanoellipsoids and a 3D N-doped porous carbon framework under non-ammonia atmosphere conditions. Integrating the F-doped Fe3N nanoellipsoids with an N-doped porous carbon framework can immensely repress the problem of volume expansion but also substantially elevate the lithium ion diffusion rate. When utilized as a negative electrode for lithium-ion batteries, this composite bespeaks a stellar operational life and rate capability, releasing a tempting capacity of 574 mAh g–1 after 550 cycles at 1.0 A g–1. The results of this study will profoundly promote the evolution and application of transition metal nitrides in batteries. [ABSTRACT FROM AUTHOR]

The rationally designed reaction between the GO sheets, Sn2+ ions and GA molecules in mild hydrothermal condition contributes to the formation of an intermediate SnO 2 @GA@RGO sample with a MOF on graphene configuration, which is converted to the final SnO 2 /C/RGO composite with optimized microstructures after thermal treatment. [Display omitted] Tin dioxide (SnO 2) is being investigated as a promising anode material for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Effectively dispersing small sized SnO 2 crystals in well-designed carbonaceous matrices using eco-friendly materials and simplified methods is an urgent task. Herein, gallic acid (GA) molecules, abundant in plant kingdom, are firstly selected to react with few-layered graphene oxide (GO) in mild hydrothermal condition, and the GA modulated reduced graphene oxide (GA@RGO) supporting skeleton can be obtained. Then Sn-GA metal–organic framework (MOF) domains can be directly engineered on the surface of the GA@RGO sheets with controlled size and improved dispersion. Finally, the well-designed Sn-GA@RGO precursor is converted to the SnO 2 /C/RGO nanocomposite with significantly optimized microstructure. The SnO 2 /C/RGO sample delivers an excellent specific capacity of 823.6 mAh·g−1 after 700 cycles at 1000 mA·g−1 in half-cells and 741.3 mAh·g−1 after 50 cycles at 200 mA·g−1 in full-cells for LIBs, a specific capacity of 370.3 mAh·g−1 after 600 cycles at 200 mA·g−1 in half-cells for SIBs. The sample preparation strategy is rationally established by comprehensively understanding the interactions between GO sheets, Sn2+ ions and GA molecules, and the engineered SnO 2 /C/RGO nanocomposite has good prospects in wider fields. [ABSTRACT FROM AUTHOR]

In this study, 1T phase MoS2 nanosheets were synthesized on the surface of a carbon cloth via a hydrothermal reaction. After heat treatment, the 1T phase MoS2 was transformed into the 2H phase with a better capacity retention performance. As an anode material for lithium-ion batteries, 2H phase MoS2 on the carbon cloth surface delivers a capacity of 1075 mAh g−1 at a current density of 0.1 A g−1 after 50 cycles; while the capacity of the 1T phase MoS2 on the surface of the carbon cloth without heat treatment fades to 528 mAh g−1. The good conductivity of a carbon cloth substrate and the separated MoS2 nanosheets help to increase the capacity of MoS2 and decrease its charge transfer resistance and promote the diffusion of lithium ions in the electrode. [ABSTRACT FROM AUTHOR]

Recently, coordination polymers (CPs) have been frequently reported in the field of energy storage as electrode materials for lithium-ion batteries (LIBs) due to their highly adjustable architectures, which have a variety of active sites and obviously defined lithium transport routes. A well-designed redox-active organic linker with potential active sites for storing lithium ions, pyrazine-2,3-dicarboxylate (H2PDA), was applied for generating CPs by a simple hydrothermal method. When employed as anode materials in LIBs, those two one-dimensional (1D) CPs with an isomorphic composition, [M(PDA)(H2O)2]n (M = Co for Co-PDA and Ni for Ni-PDA), produced outstanding reversible capacities and stable cycling performance. The Co-PDA displays a substantial reversible capacity of 936 mAh g−1 at 200 mA g−1 after 200 cycles, as well as an excellent cycling life at high currents. According to the ex situ characterizations, the high reversible specific capacity of the post-cycled electrodes was found to be a result of both the transition metal ions and the organic ligands, and Co-PDA and Ni-PDA electrode materials show reversible insertion/extraction processes that are accompanied by crystallization to an amorphous state. [ABSTRACT FROM AUTHOR]

To simultaneously reduce the cost of environmental treatment of discarded food waste and the cost of energy storage materials, research on biowaste conversion into energy materials is ongoing. This work employs a solid-state thermally assisted synthesis method, transforming natural eggshell membranes (NEM) into nitrogen-doped carbon. The resulting NEM-coated LFP (NEM@LFP) exhibits enhanced electrical and ionic conductivity that can promote the mobility of electrons and Li-ions on the surface of LFP. To identify the optimal synthesis temperature, the synthesis temperature is set to 600, 700, and 800 °C. The NEM@LFP synthesized at 700 °C (NEM 700@LFP) contains the most pyrrolic nitrogen and has the highest ionic and electrical conductivity. When compared to bare LFP, the specific discharge capacity of the material is increased by approximately 16.6% at a current rate of 0.1 C for 50 cycles. In addition, we introduce innovative data-driven experiments to observe trends and estimate the discharge capacity under various temperatures and cycles. These data-driven results corroborate and support our experimental analysis, highlighting the accuracy of our approach. Our work not only contributes to reducing environmental waste but also advances the development of efficient and eco-friendly energy storage materials. [ABSTRACT FROM AUTHOR]

Optimizing the structure of materials has proven to be an efficient solution for improving the electrochemical performance of lithium-ion batteries. In this work, SnO 2 -WS 2 -CNTS (SWC) ternary composites were prepared by hydrothermal and ball milling methods to first obtain SnO 2 -WS 2 mixture, which was then embedded on CNTS to form a special multi-level structure. Due to the special 2D structure of transition metal sulfide WS 2 and CNTS, the de-intercalation speed of lithium ions is greatly increased and the inherent particle aggregation phenomenon of SnO 2 is weakened. The three materials show their advantages while compensating for each other's disadvantages, forming an interesting synergistic effect which results in extremely stable anode materials. At 0.2Ag-1, the capacity of SWC reaches 930.71 mAhg-1 after 100 cycles, and reaches 1043 mAhg-1 after 1000 cycles at 1.0Ag-1. It is worth noting that after multiple cycles, SWC still exhibits an extremely stable state in the SEM image. The above results confirm that the special structure of SWC leads to excellent electrochemical performance, and its simple preparation method makes it a potential leading battery anode material in the future. [ABSTRACT FROM AUTHOR]

Currently, the safety of lithium-ion batteries has attracted much attention. All-solid-state batteries (ASSBs) are promising replacements for liquid-electrolyte lithium-ion batteries due to their high energy density and excellent safety. The choice of electrolyte is the most critical part of ASSBs. Li 7 La 3 Zr 2 O 12 (LLZO)-based solid-state electrolytes (SSEs) render high energy density, wide electrochemical window and high lithium-ion mobility. However, their low lithium-ion conductivity compared with liquid organic electrolytes and rigid interfacial contact at electrode/electrolyte interface mainly hinder the development of LLZO-based ASSBs. Herein, we review recent progress in the area of LLZO-based SSEs by discussing the structure and transport mechanism of lithium (Li)-ions of LLZO. Also, we summarize bottleneck problems and corresponding solutions, providing theoretical basis and technical support for the development of LLZO-based ASSBs. Finally, future prospects of LLZO-based ASSBs are discussed in next-generation energy storage systems. [ABSTRACT FROM AUTHOR]

Coordination polymers (CPs) have attracted greater scientific attention as promising electrode materials for lithium–ion batteries (LIBs) due to their diverse and versatile structural chemistry. This study introduces a croconate-based one-dimensional CP, namely [Fe(C5O5)(H2O)3]n) (referred to as Fe-CP), as an efficient anode material with high-performance characteristics for rechargeable LIBs. The ligand with abundant redox sites coordinating to the transition metal ion endowed the anode material with a remarkable stability in the electrolyte, in addition to high capacity, high-rate capability, and high cycling performance during charging/discharging process. The Fe-CP has a unique chain-based supramolecular structure, setting it apart from other porous three-dimensional molecular materials. The presence of unrestricted channels between the chains facilitates the diffusion of lithium ions in this unique structure. When tested at 100 mA g−1 over a range of voltages between 0.01 and 2.4 V, the Fe-CP anode demonstrated a noteworthy specific capacity of 521 mA h g−1 over 140 cycles. Moreover, the Fe-CP anode material exhibited excellent rate performance and demonstrated favorable cyclability. Following exposure to high charging and discharging rates of 2 A g−1, the anode ultimately regained its initial capability when the current rate was back at 100 mA g−1. [ABSTRACT FROM AUTHOR]

Lithium iron silicate (Li 2 FeSiO 4) has high theoretical capacity of 332 mAh∙g-1 upon full extraction of two lithium ions, which is accompanied by high delithiation potential and large volume change. Sulfur modification could be an effective approach for stabilizing Li 2 FeSiO 4 cathodes. A series of carbon-coated Li 2 FeSiO 4 samples were prepared through a hydrothermal and solid-state reaction route at a fixed sucrose content (14 wt% carbon) with varying amounts of sublimed sulfur at 5, 10, 15, 20 and 25 at%. The crystal structures, chemical compositions, microstructures and electrochemical performances of the differently sulfur-modified Li 2 FeSiO 4 /C were systematically investigated. The sulfur-carbon co-modifications and possible existing chemical states of sulfur are discussed in terms of the surface and near-bulk modifications. It was found that all the samples exhibited a monoclinic P 2 1 structural Li 2 FeSiO 4 , while the sulfur contents over 10 at% formed impure phases such as iron sulfides (Fe 1-x S) and lithium metasilicate (Li 2 SiO 3). Furthermore, three types of sulfur states could be found when sulfur and carbon were added simultaneously into Li 2 FeSiO 4. The surfaces were predominated by S–C and S–O–C, indicating the sulfur-carbon co-modification, which would reduce the resistance at the solid/electrode interface (SEI) but increase the charge transfer resistance. Near the bulk, the enhanced interactions between sulfur and iron S–Fe(−S) or sulfur and silicon S–Si(−O) may lead to the formation of possible impurities or oxygen substitution by sulfur. The former is detrimental as the effective sulfur amount is reduced, while the latter is beneficial to improve specific capacity and cycle stability. The overall performance of sulfur-carbon co-modified sample is influenced complicatedly by the sulfur content. The best initial discharge capacity of 152.3 mAh∙g-1 was obtained with 5 at% sulfur modification, while the best overall performance, showing a typical warm-up response and good cycle stability, was observed with 15 at% sulfur modification. [ABSTRACT FROM AUTHOR]

LiNi0.8Co0.1Mn0.1O2 (LNCMO) cathode materials for lithium-ion batteries (LIBs) were prepared by the hydrothermal synthesis of precursors and high-temperature calcination. The effect of precursor hydrothermal synthesis temperature on the microstructures and electrochemical cycling performances of the Ni-rich LNCMO cathode materials were investigated by SEM, XRD, XPS and electrochemical tests. The results showed that the cathode material prepared using the precursor synthesized at a hydrothermal temperature of 220 °C exhibited the best charge/discharge cycle stability, whose specific capacity retention rate reached 81.94% after 50 cycles. Such enhanced cyclic stability of LNCMO was directly related to the small grain size, high crystallinity and structural stability inherited from the precursor obtained at 220 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • The yolk-shell NiO/NiSe 2 @C was prepared by carbonization, selenization and oxidation of MOF precursor. • The NiO/NiSe 2 @C exhibits a high specific capacity of 992 mAh g−1 for 600 cycles at 0.2 A g−1. • DFT shows that the heterointerface is formed which enhanced the electrochemical properties. Biphasic or multiphase heterostructures have promising futures in advanced electrode materials for energy-related applications because of their desirable synergistic effects. Here we prepared a rational NiO/NiSe 2 @C heterostructure microsphere through carbonization, selenization, and oxidation using Ni-MOF as a precursor. Electrochemical studies were conducted to examine the Li+ storage characteristics, and density functional theory (DFT) was utilized to comprehend the underlying mechanism. When employed as the anode for LIBs, the NiO/NiSe 2 @C showed a high specific capacity and long-term cyclic stability, with a specific capacity of 992 mAh g−1 for 600 cycles at a current density of 0.2 A g−1. The NiO/NiSe 2 @C exhibits a significantly enhanced lithium-ion diffusion coefficient (D Li + ) value. The DFT results show that an electron-rich area forms at the NiO/NiSe 2 heterointerface, where the metalloid selenium transfers electrons to the oxygen atoms. The lithiation reactions were improved dramatically by redistributing interfacial charges, which can trigger a built-in electric field that dramatically promotes the capacitance contribution of electrode materials, enhances the lithium storage capacity, and accelerates the ion/electron transmission. The rational synthesis of NiO/NiSe 2 @C heterostructure can provide an idea for designing novel heterostructure anode materials. [ABSTRACT FROM AUTHOR]

As a typical transition-metal dichalcogenide (TMD), vanadium disulfide (VS 2) is an excellent candidate for cathode material in lithium-ion batteries due to its metallic properties and large interlayer spacing. But they often suffer from low intercalation capacity and sluggish kinetics processes, significantly limiting their practical application. Herein, the cetyltrimethylammonium bromide (CTAB) is employed in the synthesis process to construct the sulfur (S) vacancy in VS 2. The sulfur vacancy could improve its intercalation capacity and kinetics performance. In this structure, the interlayer vacancy defects could provide extra intercalation sites to improve intercalation capacity. It could induce multiple migration paths for lithium-ion (Li+) and electron (e–), enabling fast Li + migration and rapid charge transfer. It also presents favorable rate performance with a high pseudocapacitance contribution during a typical intercalation reaction. The above positive behaviors significantly promote the kinetics performance of VS 2-x as a cathode material for lithium-ion batteries (smaller charge transfer resistance and high Li+ diffusion rate). Finally, this material could provide a high storage capacity of 140 mAh g−1 after 180th and favorable rate performance (55.5 mAh g−1 at 1A g−1). This work could provide a reference for improving TMD's electrochemical performance and expanding their applications. [ABSTRACT FROM AUTHOR]

In this study, LiNi0.8Co0.15Al0.05O2@x%Al2O3-coated cathode materials were regeneratively compounded by the solid-phase sintering method, and their structural characterization and electrochemical performance were systematically analyzed. The regenerated ternary cathode material precursor synthesized by the co-precipitation method was roasted with lithium carbonate at a molar ratio of 1:1.1, and then completely mixed with different contents of aluminum hydroxide. The combined materials were then sintered at 800 °C for 15 h to obtain the regenerated coated cathode material, LiNi0.8Co0.15Al0.05O2@x%Al2O3. The thermogravimetry analysis, phase composition, morphological characteristics, and other tests show that when the added content of aluminum hydroxide is 3%, the regenerated cathode material, LiNi0.8Co0.15Al0.05O2@1.5%Al2O3, exhibits the highest-order layered structure with Al2O3 coating. This material can better inhibit the production of Ni2+, and improve material structure and electrochemical properties. The first charge–discharge efficiency of the battery assembled with this regenerated cathode material is 97.4%, a 50-cycle capacity retention is 93.4%, and a 100-cycle capacity retention is 87.6%. The first charge–discharge efficiency is far better than that of the uncoated regenerated battery. [ABSTRACT FROM AUTHOR]

Binary metal oxide stannate (M2SnO4; M = Zn, Mn, Co, etc.) structures, with their high theoretical capacity, superior lithium storage mechanism and suitable operating voltage, as well as their dual suitability for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), are strong candidates for next-generation anode materials. However, the capacity deterioration caused by the severe volume expansion problem during the insertion/extraction of lithium or sodium ions during cycling of M2SnO4-based anode materials is difficult to avoid, which greatly affects their practical applications. Strategies often employed by researchers to address this problem include nanosizing the material size, designing suitable structures, doping with carbon materials and heteroatoms, metal–organic framework (MOF) derivation and constructing heterostructures. In this paper, the advantages and issues of M2SnO4-based materials are analyzed, and the strategies to solve the issues are discussed in order to promote the theoretical work and practical application of M2SnO4-based anode materials. [ABSTRACT FROM AUTHOR]

We report an environment-friendly preparation method of rGO-based flexible self-supporting membrane electrodes, combining Co-MOF with graphene oxide and quickly preparing a hollow CoO@rGO flexible self-supporting membrane composite with a porous structure. This unique hollow porous structure can shorten the ion transport path and provide more active sites for lithium ions. The high conductivity of reduced graphene oxide further facilitates the rapid charge transfer and provides sufficient buffer space for the hollow Co-MOF nanocubes during the charging process. We evaluated its electrochemical performance in a coin cell, which showed good rate capability and cycling stability. The CoO@rGO flexible electrode maintains a high specific capacity of 1103 mAh g−1 after 600 cycles at 1.0 A g−1. The high capacity of prepared material is attributed to the synergistic effect of the hollow porous structure and the 3D reduced graphene oxide network. This would be considered a promising new strategy for synthesizing hollow porous-structured rGO-based self-supported flexible electrodes. [ABSTRACT FROM AUTHOR]

Phosphorous is an essential element for the life of organisms, and phosphorus-based compounds have many uses in industry, such as flame retardancy reagents, ingredients in fertilizers, pyrotechnics, etc. Ionic liquids are salts with melting points lower than the boiling point of water. The term "polymerized ionic liquids" (PILs) refers to a class of polyelectrolytes that contain an ionic liquid (IL) species in each monomer repeating unit and are connected by a polymeric backbone to form macromolecular structures. PILs provide a new class of polymeric materials by combining some of the distinctive qualities of ILs in the polymer chain. Ionic liquids have been identified as attractive prospects for a variety of applications due to the high stability (thermal, chemical, and electrochemical) and high mobility of their ions, but their practical applicability is constrained because they lack the benefits of both liquids and solids, suffering from both leakage issues and excessive viscosity. PILs are garnering for developing non-volatile and non-flammable solid electrolytes. In this paper, we provide a brief review of phosphonium-based PILs, including their synthesis route, properties, advantages and drawbacks, and the comparison between nitrogen-based and phosphonium-based PILs. As phosphonium PILs can be used as polymer electrolytes in lithium-ion battery (LIB) applications, the conductivity and the thermo-mechanical properties are the most important features for this polymer electrolyte system. The chemical structure of phosphonium-based PILs that was reported in previous literature has been reviewed and summarized in this article. Generally, the phosphonium PILs that have more flexible backbones exhibit better conductivity values compared to the PILs that consist of a rigid backbone. At the end of this section, future directions for research regarding PILs are discussed, including the use of recyclable phosphorus from waste. [ABSTRACT FROM AUTHOR]

The nature of the electrode–electrolyte interface has an impact on the performance and durability of lithium-ion batteries (LIBs). The initial electrolyte's thermodynamic instability at the anode–electrolyte interface in LIBs results in the formation of a passivation layer, called solid electrolyte interphase (SEI). The initial dense and intact layer allows Li + transport and restricts electron tunneling, thus preventing electrolyte decomposition and ensuring the electrochemical stability of a battery. However, the growth of this layer can reduce the availability of active lithium and electrolyte, and ultimately lead to an irreversible battery capacity fade. Investigating the transport phenomena of lithium ions within SEI is crucial for understanding its formation and growth. Nonetheless, accurately describing all relevant mechanisms is challenging due to its complex and multiscale nature. An overview of current computational efforts to study Li + transport within SEI is given in this article, ranging from electronic/atomistic scale simulations to macroscopic models. The drawbacks and advantages of the proposed numerical approaches are summarized along with the obstacles that need to be overcome to obtain accurate experimental data, identified on the basis of the most recent literature evidence. We highlight collaboration gaps between modeling and experimental approaches, as well as the urgent need for new multiscale models, to gain a better understanding of such a crucial transport phenomenon. [ABSTRACT FROM AUTHOR]

PAN/PVDF nanofiber membranes with core–shell structures were fabricated by electrospinning to improve mechanical and electrochemical properties. [Display omitted] • With the excellent mechanical properties of PAN, the mechanical strength of PAN/PVDF nanofiber separator is increased by 6 times compared with pure PVDF separator; • The PAN/PVDF nanofiber separator takes into account the high electrolyte absorption capacity of PAN and the characteristics of PVDF to promote lithium ion transport, which significantly improves the ionic conductivity, reduces the activation energy during the lithium ion transport process, and improves the battery in high-power charge and discharge performance; • The PAN/PVDF nanofiber separator promotes the uniform transport of lithium ions, thereby inhibiting the formation of lithium dendrites; The ion transport channel constructed by the separator is crucial for the practical performance of Li-ion batteries, including cycling stability and high rate capability under high current. Traditional polyolefin separator is the storage of electrolyte, which guarantees the internal ion transport process. However, its weak interaction with electrolyte and low cationic transport capacity limit the application of lithium ion battery in large current. In this study, a kind of core–shell structured polyacrylonitrile (PAN)/polyvinylidene fluoride (PVDF) nanofiber separator composed of PAN core and PVDF shell was prepared by coaxial electrospinning technique. As a result, the mechanical strength of PAN/PVDF nanofiber separator is increased from 0.6 MPa of PVDF to 3.6 MPa for PAN core. Furthermore, PAN/PVDF nanofiber separator exhibits an improved lithium-ion transference number (0.66), which is resulted from F functional groups of PVDF shell. It is believed that the interactions between the lithium ion and F functional group could construct a fast ion transport channel. The LiCoO 2 /Li half-cells assembled with PAN/PVDF exhibited higher discharge capacity (5C) than those cells using pristine PVDF, PAN separators and polyethylene (PE) separator. It is worth mentioning that the cells with PAN/PVDF separator also have excellent cycle stability. This study provides a new idea about separator-design strategy for high-performance lithium-based battery. [ABSTRACT FROM AUTHOR]

In this work, the reduced graphene oxide/NaTi2(PO4)3 (rGO/NTP) nanocomposite has been prepared by employing MXene as both the template and precursor for lithium ions battery with the enhanced performance. It is found that the NTP nanoparticles compact together and tightly decorate on the rGO layer. This novel structure benefits to shorten the diffusion path of Li+ and provide high conductivity, which are proved by the density functional calculations. Further, the Li+ diffusion coefficient of rGO/NTP is 3.68 × 10–9 cm2·s−1 which is much higher than that of the NTP (7.18 × 10–10 cm2·s−1). The results demonstrate that the rGO/NTP anode offers the high specific discharge capacity of 400.9 mAh·g−1 after 200 cycles at 0.1 A·g−1, which is nearly twice higher than that of NTP anode. Even the current density varied from 0.1 to 2 A·g−1, the specific capacity rGO/NTP anode can reach to 149.2 mAh·g−1. Further, the integrity of the lamellar structure rGO/NTP anode remained after 200 cycles, highlighting the superior stability. [ABSTRACT FROM AUTHOR]

The high energy/power lithium-ion battery using LiNi0.5Co0.2Mn0.3O2 (NCM523 HEP LIB) has an excellent trade-off between specific capacity, cost, and stable thermal characteristics. However, it still brings a massive challenge for power improvement under low temperatures. Deeply understanding the electrode interface reaction mechanism is crucial to solving this problem. This work studies the impedance spectrum characteristics of commercial symmetric batteries under different states of charge (SOCs) and temperatures. The changing tendencies of the Li+ diffusion resistance Rion and charge transfer resistance Rct with temperature and SOC are explored. Moreover, one quantitative parameter, § ≡ Rct/Rion, is introduced to identify the boundary conditions of the rate control step inside the porous electrode. This work points out the direction to design and improve performance for commercial HEP LIB with common temperature and charging range of users. [ABSTRACT FROM AUTHOR]

TiO2 is a promising anode material for lithium-ion batteries (LIBs) due to its low cost, suitable operating voltage, and excellent structural stability. The inherent poor electron conductivity and low ion diffusion coefficient, however, severely limit its application in lithium storage. Here, Co-doped TiO2 is synthesized by a hydrothermal method as an anode material since Co@TiO2 possesses a large specific surface area and high electronic conductivity. Thanks to the Co dopants, the ion diffusion and electron transport are both greatly improved, which is very beneficial for cycle stability, coulombic efficiency (CE), reversible capacity, and rate performance. As a result, Co@TiO2 shows a high reversible capacity of 227 mAh g−1 at 3 C, excellent rate performance, and cycling stability with a capacity of about 125 mAh g−1 at 10C after 600 cycles (1 C = 170 mA g−1). [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? Rapid acquisition technology of electrochemical impedance spectroscopy. EIS was used to quickly and effectively estimate the SOH of LIBs. Machine learning method and equivalent circuit method to estimate battery health state. What is the implication of the main finding? EIS were found to be better SOH estimation method. The technology based on EIS has the characteristics of high precision advantages. The method based on EIS of LIBs SOH estimation has been applied to the BMS. Lithium-ion batteries stand out from other clean energy sources because of their high energy density and small size. With the increasing application scope and scale of lithium-ion batteries, real-time and accurate monitoring of its state of health plays an important role in ensuring the healthy and stable operation of an energy storage system. Due to the interaction of various aging reactions in the aging process of lithium-ion batteries, the capacity attenuation shows no regularity. However, the traditional monitoring method is mainly based on voltage and current, which cannot reflect the internal mechanism, so the accuracy is greatly reduced. Recently, with the development of electrochemical impedance spectroscopy, it has been possible to estimate the state of health quickly and accurately online. Electrochemical impedance spectroscopy can measure battery impedance in a wide frequency range, so it can reflect the internal aging state of lithium-ion batteries. In this paper, the latest impedance spectroscopy measurement technology and electrochemical impedance spectroscopy based on lithium-ion battery health state estimation technology are summarized, along with the advantages and disadvantages of the summary and prospects. This fills the gap in this aspect and is conducive to the further development of this technology. [ABSTRACT FROM AUTHOR]

Batteries are complex systems involving spatially distributed microscopic mechanisms on different time scales whose adequate interplay is essential to ensure a desired functioning. Describing these phenomena yields nonlinearly coupled partial differential equations whose numerical solution requires considerable effort and computation time, making it an infeasible solution for real-time applications. Anyway, having information about the internal electrochemical states of the battery can pave the way for many different advanced monitoring and control strategies with a big potential for improving efficiency and longevity. For such purposes, in the present paper, a combination of a low-order representation of the essential dynamics associated to the internal electrochemical mechanisms based on Dynamic Mode Decomposition for control (DMDc) is proposed to obtain an improved equivalent circuit model (ECM) representation with continuously updated parameters and combined with an extended Kalman Filter (EKF). The model-order reduction step extensively exploits the model structure, yielding a well structured low-order representation without artificial numerical correlations. The performance of the proposed method is illustrated with numerical simulations based on a well-established reference model, showing its potential usefulness in real-time applications requiring knowledge of the internal electrochemical states besides the state-of-charge. [ABSTRACT FROM AUTHOR]

Mechanical stability of the solid electrolyte interphase (SEI) is crucial to mitigate the capacity fade of lithium–ion batteries because the rupture of the SEI layer results in further consumption of lithium ions in newly generated SEI layers. The SEI is known as a heterogeneous bilayer and consists of an inner inorganic layer connecting the particle and an outer organic layer facing the electrolyte. The growth of the bilayer SEI over cycles alters the stress generation and failure possibility of both the organic and inorganic layers. To investigate the probability of mechanical failure of the bilayer SEI, we developed the electrochemical-mechanical coupled model with the core–double-shell particle/SEI layer model. The growth of the bilayer SEI is considered over cycles. Our results show that during charging, the stress of the particle changes from tensile to compressive as the thickness of bilayer SEI increases. On the other hand, in the SEI layers, large compressive radial and tensile tangential stress are generated. During discharging, the compressive radial stress of the bilayer SEI transforms into tensile radial stress. The tensile tangential and radial stresses are responsible for the fracture and debonding of the bilayer SEI, respectively. As the thickness ratio of the inorganic to organic layers increases, the fracture probability of the inorganic layer increases, while that of the organic layer decreases. However, the debonding probability of both layers is decreased. In addition, the SEI covering large particles is more vulnerable to fracture, while that covering small particles is more susceptible to debonding. Therefore, tailoring the thickness ratio of the inorganic to organic layers and particle size is important to reduce the fracture and debonding of the heterogeneous bilayer SEI. [ABSTRACT FROM AUTHOR]

[Display omitted] V 2 CT x MXene has shown potential as an electrode material for lithium-ion batteries (LIBs) due to its high theoretical capacity. However, most reports on V 2 CT x are confined to multilayer structures in LIBs, and V 2 CT x nanosheets have a serious restacking problem, which results in their low cyclic stability. Herein, we report the synthesis of few-layer V 2 CT x /carbon nanotubes (CNTs) composite by tetramethylammonium hydroxide (TMAOH) delamination and electrostatic flocculation of NH 4 + ions. Few-layer V 2 CT x nanosheets with crimped structure can effectively restrain restacking and guarantee full utilization of active surface area. Moreover, with the introduction of CNTs, a developed electrical conductivity network was formed, and CNTs provided structural support for the sheets further restraining their restacking, and ensuring their stable structure during the charge and discharge process even at high rates. This made the few-layer V 2 CT x /CNT to exhibit a high specific capacitance of 621 mAh/g after 100 cycles at 0.1 A/g, and outstanding rate performance of 290 mAh/g at 5 A/g. Furthermore, the few-layer V 2 CT x /CNT electrode showed excellent cycling stability with 82.1 % capacitance retention after 2000 cycles at 5 A/g. This shows it has significant potential for lithium-ion batteries applications. [ABSTRACT FROM AUTHOR]

[Display omitted] V 2 CT x MXene has shown potential as an electrode material for lithium-ion batteries (LIBs) due to its high theoretical capacity. However, most reports on V 2 CT x are confined to multilayer structures in LIBs, and V 2 CT x nanosheets have a serious restacking problem, which results in their low cyclic stability. Herein, we report the synthesis of few-layer V 2 CT x /carbon nanotubes (CNTs) composite by tetramethylammonium hydroxide (TMAOH) delamination and electrostatic flocculation of NH 4 + ions. Few-layer V 2 CT x nanosheets with crimped structure can effectively restrain restacking and guarantee full utilization of active surface area. Moreover, with the introduction of CNTs, a developed electrical conductivity network was formed, and CNTs provided structural support for the sheets further restraining their restacking, and ensuring their stable structure during the charge and discharge process even at high rates. This made the few-layer V 2 CT x /CNT to exhibit a high specific capacitance of 621 mAh/g after 100 cycles at 0.1 A/g, and outstanding rate performance of 290 mAh/g at 5 A/g. Furthermore, the few-layer V 2 CT x /CNT electrode showed excellent cycling stability with 82.1 % capacitance retention after 2000 cycles at 5 A/g. This shows it has significant potential for lithium-ion batteries applications. [ABSTRACT FROM AUTHOR]

Co-free layered LiNi0.5Mn0.5O2 has received considerable attention due to high theoretical capacity (280 mAh g−1) and low cost comparable than LiCoO2. The ability of nickel to be oxidized (Ni2+/Ni3+/Ni4+) acts as electrochemical active and has a low activation energy barrier, while the stability of Mn4+ provides a stable host structure. However, selection of appropriate preparation method and condition are critical to providing an ideal layered structure of LiNi0.5Mn0.5O2 with good electrochemical performance. In this study, Layered LiNi0.5Mn0.5O2 has been synthesized by sol-gel and solid-state routes. According to the XRD, the sol-gel method provides a pure phase, and solid-state process only minimize the secondary phases to certain limit. The Ni2+/Mn4+ content in the sol-gel process was higher than in the solid-state reaction, which may be due to the chemical composition homogeneity of the sol-gel samples. Regarding the electrochemical behavior, sol-gel process is better than solid-state reaction. The discharge capacity is 145 mAh/g and 91 mAh/g for the sol-gel process and solid-state reaction samples, respectively. [ABSTRACT FROM AUTHOR]

Owing to their high redox potential and availability of numerous diffusion channels in metal–organic frameworks, Prussian blue analogs (PBAs) are attractive for metal ion storage applications. Recently, vanadium ferrocyanides (VFCN) have received a great deal of attention for application in sodium-ion batteries, as they demonstrate a stable capacity with high redox potential of ~3.3 V vs. Na/Na+. Nevertheless, there have been no reports on the application of VFCN in lithium-ion batteries (LIBs). In this work, a facile synthesis of VFCN was performed using a simple solvothermal method under ambient air conditions through the redox reaction of VCl3 with K3[Fe(CN)6]. VFCN exhibited a high redox potential of ~3.7 V vs. Li/Li+ and a reversible capacity of ~50 mAh g–1. The differential capacity plots revealed changes in the electrochemical properties of VFCN after 50 cycles, in which the low spin of Fe ions was partially converted to high spin. Ex situ X-ray diffraction measurements confirmed the unchanged VFCN structure during cycling. This demonstrated the high structural stability of VFCN. The low cost of precursors, simplicity of the process, high stability, and reversibility of VFCN suggest that it can be a candidate for large-scale production of cathode materials for LIBs. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotubes (SWCNTs) with their high surface area, electrical conductivity, mechanical strength and elasticity are an ideal component for the development of composite electrode materials for batteries. Red phosphorus has a very high theoretical capacity with respect to lithium, but has poor conductivity and expends considerably as a result of the reaction with lithium ions. In this work, we compare the electrochemical performance of commercial SWCNTs with red phosphorus deposited on the outer surface of nanotubes and/or encapsulated in internal channels of nanotubes in lithium-ion batteries. External phosphorus, condensed from vapors, is easily oxidized upon contact with the environment and only the un-oxidized phosphorus cores participate in electrochemical reactions. The support of the SWCNT network ensures a stable long-term cycling for these phosphorus particles. The tubular space inside the SWCNTs stimulate the formation of chain phosphorus structures. The chains reversibly interact with lithium ions and provide a specific capacity of 1545 mAh·g−1 (calculated on the mass of phosphorus in the sample) at a current density of 0.1 A·g−1. As compared to the sample containing external phosphorus, SWCNTs with encapsulated phosphorus demonstrate higher reaction rates and a slight loss of initial capacity (~7%) on the 1000th cycle at 5 A·g−1. [ABSTRACT FROM AUTHOR]

A carbon superstructure material (PTA-700) was synthesized by a simple self-assembly method and one-step carbonization, and showed remarkable high energy and long cycle life stability in lithium/sodium ion half battery. [Display omitted] Due to abundant resources and low prices, biomass-derived carbons as anodes for lithium ion batteries (LIBs) and sodium ion batteries (SIBs) have been widely reported. However, it is still a challenge to design a biomass-derived carbon material that has immunity to environmental influences, stable chemical composition and controllable morphology. In this paper, tannic acid (TA) as a precursor is first reported to synthesize rod structures with abundant mesopores and defects (PTA-700). These features can provide more active sites and space for lithium and sodium ions storage, which is conducive to lithium and sodium ions transfer. Excellent electrochemical performance is observed in LIBs (535 mAh/g after 100 cycles at 0.1 A/g) and SIBs (114.0 mAh/g after 3000 cycles at 1 A/g). Kinetics analysis and density functional theory (DFT) calculations were carried out to further analyze the superior lithium and sodium ions storage performance of PTA-700. More importantly, PTA-700 solves many problems faced by traditional biomass-derived carbons in commercialization. Our work suggests an effective way to develop high-performance biomass-derived carbon anode materials for LIBs and SIBs. [ABSTRACT FROM AUTHOR]

Electrochemical stress induced by the charging/discharging of electrode materials strongly affects the lifetime of lithium-ion batteries (LIBs) by regulating mechanical failures. Electrochemical stress is caused by a change in the local volume of the active materials associated with the lithium-ion concentration. The local volume change of certain active materials, such as nickel-rich LiNixMnyCozO2 (NMC), varies nonlinearly with the lithium content, which has not been considered in the stress calculations in previous studies. In this paper, the influence of nonlinear local volume change on the mechanical response of NMC-active materials is investigated numerically. The goal is achieved by using a concentration-dependent partial molar volume calculated from the previously obtained local volume change experimental results. A two-dimensional axisymmetric model was developed to perform finite element simulations by fully coupling lithium diffusion and stress generation at a single particle level. The numerical results demonstrate that (1) the global volume change of the particle evolves nonlinearly, (2) the stress response correlates with the rate of change of the active particle's volume, and (3) stress–concentration coupling strongly affects the concentration levels inside the particle. We believe this is the first simulation study that highlights the effect of a concentration-dependent partial molar volume on diffusion-induced stresses in NMC materials. The proposed model provides insight into the design of next-generation NMC electrode materials to achieve better structural stability by reducing mechanical cracking issues. [ABSTRACT FROM AUTHOR]

This work introduces a one-step method for the preparation of layered oxide cathode materials utilizing pure Ni and Co mixed solution obtained from the waste hydrodesulfurization (HDS) catalyst. An efficient non-separation strategy with pyrometallurgical-hydrometallurgical (pyro-hydrometallurgical) process consisting of roasting and leaching is proposed. Most of the impurity metal elements such as Mo and V were removed by simple water leaching after the waste HDS catalyst was roasted with Na2CO3 at 650 °C for 2.5 h. Additionally, 93.9% Ni and 100.0% Co were recovered by H2SO4 leaching at 90 °C for 2.5 h. Then, LiNi0.533Co0.193Mn0.260V0.003Fe0.007Al0.004O2 (C–NCM) was successfully synthesized by hydroxide co-precipitation and high temperature solid phase methods using the above Ni and Co mixed solution. The final C–NCM material exhibits excellent electrochemical performance with a discharge specific capacity of 199.1 mAh g−1 at 0.1 C and a cycle retention rate of 79.7% after 200 cycles at 1 C. This novel process for the synthesis of cathode material can significantly improve production efficiency and realize the high added-value utilization of metal resources in a waste catalyst. [ABSTRACT FROM AUTHOR]

A surficial engineering strategy for single-crystalline LiNi 0.83 Co 0.11 Mn 0.06 O 2 (SCNCM) via Li 1.3 In 0.3 Ti 1.7 (PO 4) 3 (LITP) modification is proposed to promote the Li-ions distribution. Notably, the fast Li-ion conductor LITP can not only accelerate the Li-ions diffusion and alleviate the electrode–electrolyte side reaction simultaneously, but also serve as the Li-ions regulator to ensure the homogeneous distribution of Li-ions and minimizing the concentration difference at SCNCM surface. It provides the instructive guide for the modification of single-crystalline micron-sized particles for commercialization development of advanced NCM cathode at harsh testing condition. [Display omitted] Nickel-rich layered LiNi x Co y Mn 1- x - y O 2 (NCM, x ≥ 0.83) is considered as a promising cathode material for lithium-ion batteries (LIBs), owing to its satisfying specific energy. However, the undesired phase transformation from layered into rock-salt at the NCM surface will easily induce Li concentration gradient during cycling, which hinders the Li-ions diffusion and leads to the gradual accumulation of inner stress with the appearance of microcracks. Herein, we propose a surficial engineering strategy to promote the Li-ions transmission for single-crystalline LiNi 0.83 Co 0.11 Mn 0.06 O 2 (SCNCM) via Li 1.3 In 0.3 Ti 1.7 (PO 4) 3 (LITP) modification. It is noted that, as the fast Li-ion conductor, LITP can accelerate the Li-ions diffusion and alleviate the electrode–electrolyte side reaction simultaneously. More importantly, LITP can serve as the Li-ions regulator, ensuring the homogeneous distribution of Li-ions and minimizing the concentration difference at SCNCM surface. It can relieve the stress induced by the inconsistent Li-ions dispersion, which effectively decreases the degree of structural disordering and lattice mismatch at surface, eventually maintaining the high structure integrity during long-term cycling. As anticipated, even under the harsh testing conditions, the LITP modified SCNCM still can achieve a satisfied reversible capacity of 196.4 mAh g−1 under potential range of 2.75–4.6 V after 200 cycles at 25 °C in coin-type half-cells. Furthermore, it provides an extraordinary capacity retention of 88% in 2.75–4.3 V after 400 cycles at high temperature of 45 °C in pouch-type full-battery. [ABSTRACT FROM AUTHOR]

Nowadays, lithium-ion batteries are one of the most widespread energy storage systems, being extensively employed in a large variety of applications. A significant effort has been made to develop advanced materials and manufacturing processes with the aim of increasing batteries performance and preserving nominal properties with cycling. Nevertheless, mechanical degradation is still a significant damaging mechanism and the main cause of capacity fade and power loss. Lithium ions are inserted and extracted into the lattice structure of active materials during battery operation, causing the deformation of the crystalline lattice itself. Strain mismatches within the different areas of the active material caused by the inhomogeneous lithium-ions concentration induce mechanical stresses, leading ultimately to fracture, fatigue issues, and performance decay. Therefore, a deep understanding of the fracture mechanics in active materials is needed to meet the rapidly growing demand for next-generation batteries with long-term stability, high safety, excellent performance, and long life cycle. This review aims to analyze the fracture mechanics in the active material microstructure of electrodes due to battery operations from an experimental point of view. The main fracture mechanisms occurring in the common cathode and anode active materials are described, as well as the factors triggering and enhancing fracture. At first, the results obtained by performing microscopy and diffraction analysis in different materials are discussed to provides visual evidence of cracks and their relation with lattice structure. Then, fatigue phenomena due to crack growth as a function of the number of cycles are evaluated to assess the evolution of damage during the life cycle, and the effects of fracture on the battery performance are described. Finally, the literature gaps in the characterization of the fracture behavior of electrode active materials are highlighted to enhance the development of next-generation lithium-ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Polymer materials containing C 6 rings and C O become promising electrode materials for high-performance lithium ion batteries (LIBs). However, the poor electronic conductivity severely restricts its further application. Herein, we design and construct a pyromellitic dianhydride anhydride anthraquinone/reduced graphene oxides (PMAQ/rGO-40) composite as an anode material for LIBs. The PMAQ is uniformly wrapped by conductive rGO nanosheets. The PMAQ/rGO-40 electrode without additional conductive agents displays a discharge capacity of 253 mAh g−1 over 3000 cycles under 2A g−1, which is higher than that of the PMAQ electrode with conductive agents. Meanwhile, a capacity of 196 mAh g−1 is achieved under 5A g−1. The enhanced cycling performance and rate ability are attributed to the rGO conductive network, which promotes electronic transport capability. In addition, the lithium ion storage mechanism and kinetics in the PMAQ/rGO-40 are investigated. The excellent electrochemical performance shows the potential application of the PMAQ/rGO composite anode material for high performance LIBs. [ABSTRACT FROM AUTHOR]

Due to their safety and sustainability, polysaccharides such as cellulose and chitosan have great potential to be the matrix of gel polymer electrolytes (GPE) for lithium-based batteries. However, they easily form hydrogels due to the large numbers of hydrophilic hydroxyl or amino functional groups within their macromolecules. Therefore, a polysaccharide-based amphiphilic gel, or organogel, is urgently necessary to satisfy the anhydrous requirement of lithium ion batteries. In this study, a PEGylated chitosan was initially designed using a chemical grafting method to make an GPE for lithium ion batteries. The significantly improved affinity of PEGylated chitosan to organic liquid electrolyte makes chitosan as a GPE for lithium ion batteries possible. A reasonable ionic conductivity (1.12 × 10−3 S cm−1) and high lithium ion transport number (0.816) at room temperature were obtained by replacing commercial battery separator with PEG-grafted chitosan gel film. The assembled Li/GPE/LiFePO4 coin cell also displayed a high initial discharge capacity of 150.8 mA h g−1. The PEGylated chitosan-based GPE exhibits great potential in the field of energy storage. [ABSTRACT FROM AUTHOR]

A nanostructured Ni-ferrite material, NiFe 2 O 4 , was successfully synthesized via facile co-precipitation in hot water, followed by an annealing process. The developed Ni-ferrite was face-centered cubic, highly crystalline, and nano-sized. The Ni-ferrite anode revealed superior electrochemical properties for Li-ion batteries, such as high reversible capacity and long cyclability, without significant capacity fading. Specifically, this anode exhibited reversible capacities of 926 and 1586 mAh g−1 at the 1st and 150th cycles at 0.1 A g−1, respectively. The superior electrochemical performance was attributed to the size and unique properties of the Ni-ferrite spinel. Nano-sized materials were beneficial for creating a large contact area between the electrode and electrolyte, increasing diffusion rates of lithium ions, resulting in enhanced pseudo-behavior. The properties of spinel structure and the presence of Fe and Ni metals during charge/discharge in Ni-ferrite prevented the destruction of the anode and catalyzed the decomposition of the Li 2 O phase, leading to extraordinary highly-reversible Li storage. [Display omitted] • Spinel Ni-ferrite is prepared via a simple coprecipitation route. • Spinel Ni-ferrite possesses nanostructures (from 20 to 65 nm) with high crystallinity. • Detailed pseudo and diffusive behaviors of Ni-ferrite electrode are investigated via mathematic method. • Spinel Ni-ferrite demonstrates a high reversible capacity (∼1586 mAh g−1 at 150 cycles). [ABSTRACT FROM AUTHOR]

Lithium ion battery is a complex system, and any change in device parameters may significantly affect the overall performance. The prediction of battery behavior based on theoretical simulation is of great significance. In this work, the battery performance with LiNi1/3Co1/3Mn1/3O2 electrodes of different active material loading amounts was theoretically investigated, such as battery rate performance, capacity decay rate, energy and power density, SOC (State of Charge) change, temperature response, and heat source distribution. A 1D electrochemical–3D thermal coupling model was established, and the accuracy and predictability of the model were verified by experiments. An in-depth analysis of batteries under different discharge rates and batteries with different electrode loading amounts is carried out. The results show that the rate performance and capacity change with different electrode loading amounts, which is attributed to the variation in lithium ion diffusion. At the same time, the change in load affects the growth of lithium dendrites and the distribution of SOC, resulting in the thermal runaway of the battery and shortening the battery life. [ABSTRACT FROM AUTHOR]

[Display omitted] For a long time, carbon has been an ideal material for various electrochemical energy storage devices and a key component in electrochemical energy storage systems due to its advantages of rich surface states, easy tenability, and good chemical stability. Stable and high-performance carbon materials can support future applications of high specific energy electrodes. Herein and for the first time, we have designed nitrogen-doped carbon hollow containers using oleylamine-coating TiO 2 mesocrystals as a precursor with a high specific surface area of 1231 m2 g−1. When applied as an anode for lithium-ion storage, a reversible capacity of 774.5 mA h g−1 is obtained at a rate of 0.5 A g−1 after 200 cycles. Meanwhile, at an even higher rate of 2 A g−1, a capacity of 721.1 mA h g−1 is still achieved after 500 cycles. Moreover, the carbon containers remain structurally intact after a series of cycles. This may be attributed to the nitrogen atoms doped on the carbon surface that can absorb multiple lithium ions and enhance the structural stability. These results provide technical support for the development of high specific energy electrode materials. [ABSTRACT FROM AUTHOR]

Most cathode materials for Li-ion batteries exhibit a low electronic conductivity. Therefore, a considerable amount of conductive additives is added during electrode production. A mixed phase of carbon and binder provides a 3D network for electron transport and at the same time improves the mechanical stability of the electrodes. However, this so-called carbon binder domain (CBD) hinders the transport of lithium ions through the electrolyte and reduces the specific energy of the cells. Therefore, the CBD content is an important design parameter for optimal battery performance. In the present study, stochastic 3D microstructure modeling, microstructure characterization, conductivity simulations as well as microstructure-resolved electrochemical simulations are performed to identify the influence of the CBD content and its spatial distribution on electrode performance. The electrochemical simulations on virtual, but realistic, electrode microstructures with different active material content and particle size distributions provide insights to limiting transport mechanisms and optimal electrode configurations. Furthermore, we use the results of both the microstructure characterization and electrochemical simulations to deduce extensions of homogenized cell models providing improved predictions of cell performance at low CBD contents relevant for high energy density batteries. [ABSTRACT FROM AUTHOR]

Transient nonlinear problems play an important role in many engineering problems. Phase-field equations, including the well-known Allen-Cahn and Cahn-Hilliard equations, fall in this category, and have applications in cutting-edge technologies such as modeling the diffusion of lithium (Li) ions in two-phase electrode particles of Li-ion batteries. In this paper, a local meshless method for solving this category of partial differential equations (PDEs) is proposed. The Newton-Kantorovich scheme is employed to transform the nonlinear PDEs to an iterative series of linear ones which can be solved with the proposed method. The accuracy and performance of the method are examined in various linear and nonlinear problems, such as Laplace equation, three dimensional elasticity as well as some abstract mathematical equations with linear or nonlinear boundary conditions. The main focus of the work is on applying the proposed method in solution of the phase-field equations, including the Allen-Cahn and Cahn-Hilliard equations. In addition to homogeneous Neumann boundary condition which has been widely examined in the literature, we also employ a practical nonlinear, inhomogeneous Neumann boundary condition formulation specialized for modeling the diffusion of lithium ions in electrode particles of Li-ion batteries. The generalized- α method is used for time integration of diffusion-type equations to overcome the intrinsic stiffness of the phase-field equations. It is shown that the method is capable of capturing the main features of the phase-field models i.e. phase separation, coarsening and energy decay in closed systems. [ABSTRACT FROM AUTHOR]

A small amount of tin ions modified covalent organic framework hollow microsphere (Sn@COF-hollow) is designed and demonstrated with more active sites, facilitated lithium-storage kinetic and highly reversible large capacities. [Display omitted] • Sn-doped COF layer-assembled hollow microspherical composite is fabricated via the Sn-N coordination. • The Sn@COF-hollow is adopted as the electrode for lithium-ion battery for the first time. • Enhanced electrochemical performances can be achieved for the Sn@COF-hollow electrode. • Lithium-reaction activation on Sn centers, C C and C N groups can be boosted for the Sn@COF-hollow electrode. Covalent-organic frameworks (COFs) and related composites show an enormous potential in next-generation high energy-density lithium-ion batteries. However, the strategy to design functional covalent organic framework materials with nanoscale structure and controllable morphology faces serious challenges. In this work, a layer-assembled hollow microspherical structure (Sn@COF-hollow) based on the tin-nitrogen (Sn-N) coordination interaction is designed. Such carefully-crafted hollow structure with large exposed surface area and metal center decoration endows the Sn@COF-hollow electrode with more activated lithium-reaction sites, including Sn ions, carbon-nitrogen double bond (C N) groups and carbon-carbon double bond (C C) units from aromatic benzene rings. Besides, the layer-assembled hollow structure of the Sn@COF-hollow electrode can also alleviate the volume expansion of electrode during repeated cycling, and achieve fast electrons/ions transmission and capacitance-dominated lithium-reaction kinetics, further leading to enhanced cycling performance and rate properties. In addition, the effective combination of the inorganic metal and organic framework components in the Sn@COF-hollow electrode can promote its improved conductivity and further enhance lithium-storage properties. Benefited from these merits, the Sn@COF-hollow electrode delivers highly reversible large capacities of 1080 mAh g−1 after 100 cycles at 100 mA g−1 and 685 mAh g−1 after 300 cycles at 1000 mA g−1. This work provides an interesting and effective way to design COF-based anodes of lithium-ion battery with improved electrochemical performances. [ABSTRACT FROM AUTHOR]

The evolution of α-Fe 2 O 3 nanostructures from pie-like α-Fe 2 O 3 spheres (P-Fe 2 O 3), to hollow bowl-like α-Fe 2 O 3 spheres (B-Fe 2 O 3) and then to α-Fe 2 O 3 nanorings (R-Fe 2 O 3) have been successfully achieved through a facile hydrothermal approach and the designed hollow bowl-like α-Fe 2 O 3 (B-Fe 2 O 3) spheres exhibit great advantages as a LIB anode material. [Display omitted] The design and synthesis of hollow-nanostructured transition metal oxide-based anodes is of great importance for long-term operation of lithium ion batteries (LIBs). Herein, a special hollow bowl-like α-Fe 2 O 3 nanostructure is controllably synthesized through a facile hydrothermal technique and exhibits great electrochemical lithium storage performance when used as LIBs anode. Under a facile hydrothermal condition, α-Fe 2 O 3 nanostructures evolve from solid pie-like structure to hollow bowl-like structure and finally α-Fe 2 O 3 nanorings through the regulation of HPO 4 - derived from ionized Na 3 PO 4 ·12H 2 O and Ostwald ripening process. The designed hollow bowl-like α-Fe 2 O 3 nanostructure not only has the merits of hollow structure, which can accelerate the diffusion of lithium ions and electrons, but also shows great mechanical strength to disperse stress when compared to solid pie-like and ring-like α-Fe 2 O 3 nanostructures, which would avoid collapse during charge/discharge process. As a result, the as-synthesized hollow bowl-like α-Fe 2 O 3 nanostructure displays an initial reversible capacity of 1616 mAh g−1 at a current density of 1 A g−1, an excellent cycling performance with a reversible capacity of 1018 mAh g−1 after 500 cycles and an outstanding rate capability (68.1% capacity retention at current densities from 100 to 2000 mA g−1). This work provides not only a novel hollow bowl-like α-Fe 2 O 3 nanostructure with high specific surface area and stable structure as potential electrode materials for energy storage, but also a facile self-templated strategy free of any surfactants and templates for hollow nanostructures. [ABSTRACT FROM AUTHOR]

Highlights: EIS was used to estimate the SOH of LIBs found to be fast and effective. It is more convenient to use CNN to extract features of EIS data automatically. The improved ECM method and IPSO-CNN-BiLSTM method are proposed in this paper. IPSO algorithm was first proposed to applied to the problem of optimizing the initial parameters of the neural networks. The state of health (SOH) is critical to the efficient and reliable use of lithium-ion batteries (LIBs). Recently, the SOH estimation method based on electrochemical impedance spectroscopy (EIS) has been proven effective. In response to different practical applications, two models for SOH estimation are proposed in this paper. Aiming at based on the equivalent circuit model (ECM) method, a variety of ECMs are proposed. Used EIS to predict the ECM, the results show that the improved method ensures the correctness of the ECM and improves the estimation results of SOH. Aiming at a data-driven algorithm, proposes a convolution neural network (CNN) to process EIS data which can not only extract the key points but also simplifies the complexity of manual feature extraction. The bidirectional long short-term memory (BiLSTM) model was used for serial regression prediction. Moreover, the improved Particle Swarm Optimization (IPSO) algorithm is proposed to optimize the model. Comparing the improved model (IPSO-CNN-BiLSTM) with the traditional PSO-CNN-BiLSTM, CNN-BiLSTM and LSTM models, the prediction results are improved by 13.6%, 93.75% and 94.8%, respectively. Besides that, the two proposed methods are 27% and 35% better than the existing gaussion process regression (GPR) model, which indicates that the proposed improved methods are more flexible for SOH estimation with higher precision. [ABSTRACT FROM AUTHOR]