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[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]

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]

[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]

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]

[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]

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]

[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]

[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]

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]

Metal-organic frameworks (MOFs) materials have been widely researched in energy conversion systems because of porosity and active sites. However, applying MOF as an electrode material remains challenging because of its structural instability. In this work, two novel materials are designed to promote the research of MOFs-based electrode materials for lithium-ion batteries (LIBs). Two ternary metallic ions (Mn2+, Co2+, Ni2+) constituent MOFs with two- and three-dimensional (3D) structures are synthesized by combining with benzene-1,2,3,4,5,6-hexacarboxylate (BHC) ligand via a simple hydrothermal method. The structures of MCN-1 and MCN-2 belong to monoclinic symmetry, C 2/ c space group. The 3D structure of MCN-2 can enhance the interfacial contact between electrode materials and electrolytes and provide more active sites for the storage of Li+. Electrochemical experiments show that the 3D structure ternary MOF delivers an ultra-high capacity of 807.3 mAh g−1 after 100 cycles at 100 mA g−1, even though a phase transition occurs during the electrochemical process. This superior performance is rationally owing to the synergetic mechanism of intercalation/deintercalation combined with capacitance behavior, which has broad application prospects as anode material. [Display omitted] • Two novel ternary MOF materials containing Mn2+, Co2+ and Ni2+ were designed and synthesized by one-step hydrothermal method. • The synergistic effect of multiple metals increase the conductivity and the electrochemical properties of the materials. • 3D MCN-2 maintains a high specific capacity of 807.3 mAh g−1 after 100 cycles, showing excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Spinel structured α-LiFe 5 O 8 were prepared via ball milling combined with a straightforward solid-phase method, using Fe 2 O 3 and Li 2 CO 3 as the raw materials. The material maintained a stable capacity of 440 mAh g−1 after 200 cycles at 900 mA g−1 with Coulomb efficiency more than 95 % and also showed facile lithium ion diffusion dynamics. The calculated diffusion coefficient of α-LiFe5O8 ranged around 10−10-10−12 cm2 s−1. Diffusion controlled contribution was dominant over capacitive contribution in the sweeping range 0.1–1.5 mV s−1. A new intercalation-decomposition-conversion mechanism was proposed on the basis that there existed a small pit at the initial stage of the discharge plateau and a significantly low initial discharge plateau voltage was observed compared with the followed discharge cycles. Based on the DFT calculations and the phase diagram of the Li–Fe–O system, we supposed that for the initial discharge of the material, after 1 mol of lithium ion intercalation per unit formula, α-LiFe 5 O 8 decomposed to LiFeO 2 and Fe 3 O 4. The followed discharge was the conversion of both LiFeO 2 and Fe 3 O 4 to metal Fe and Li 2 O. Thereafter, the system cycled between Fe 2 O 3 at the fully charged state and metal Fe and Li 2 O at the fully discharged state. Li–Fe–O phase diagram used to disclose the conversion mechanism. [Display omitted] • Unmodified α-LiFe 5 O 8 show good electro-chemical performance. • Li+ transportation kinetics reveals the features of fast ion conductor. • A new intercalation-decomposition-conversion mechanism was proposed. [ABSTRACT FROM AUTHOR]

In this particular investigation, the tetragonal α 1 -LiVOPO 4 cathode material was successfully synthesized employing a sol-gel technique for the first time. The X-ray diffraction studies have confirmed the tetragonal structure with the space group P4/nmm. A range of characterizations, such as Fourier-transformed infrared spectroscopy and magnetic measurements, have been executed. The Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS) has been employed to assess the surface morphology and chemical composition of the sample produced. Additionally, electrochemical measurements, including galvanostatic charge-discharge, cyclic voltammetry, and Electrochemical Impedance Spectroscopy (EIS), have been conducted. The material has demonstrated an outstanding electrochemical performance, which can be attributed to the facile diffusion of Li+ ions along a two-dimensional pathway and the efficient charge transfer process. [Display omitted] • The cathode LiVOPO 4 with tetragonal structure, has been effectively produced via the sol-gel for the first time. • The XRD, Infra-red and magnetic results confirm the tetragonal structure of LiVOPO 4 with a small amount of impurties. • The porosity of theobtained material contributes to the improvement of the electrochemical performance of the LiVOPO 4. • The EIS result shows a good electronic and ionic conductivity of the tetragonal LiVOPO 4 synthesis by the sol-gel method. [ABSTRACT FROM AUTHOR]

[Display omitted] • It is the first time to systematically study the influence of water in electrodes on the performances of micro lithium-ion batteries. • An overgrowth of the solid electrolyte interphase film happens after activation with the growth of the water content. • The SEI film forming under high water content is less stable. During the production of micro lithium-ion batteries (LIBs), which are widely used in wireless headphones and other small portable devices, numerous factors can affect their quality, among which the content of water plays a crucial role. In this work, the influence of water in electrodes on the performances of micro LIBs is studied deeply. When the content of water increases, both the rate performance and the cycling performance of the batteries fade. The discharge capacity retention of the battery from high water content sample group H (group H) is 81.81% after 350 cycles at 2C, while that of the battery from low water content sample group L (group L) is 89.89% under the same condition. As for the rate performance, the discharge capacity of group H is only 58.66% of group L at 5C. To take a step further, it is mainly because an overgrowth of the solid electrolyte interphase film happen with the growth of water content. Accordingly, excess lithium ions are consumed and the porous structure of the anode is destroyed. Considering the results above, we believe that this work can offer a theory foundation to carry out the failure analysis of micro batteries. [ABSTRACT FROM AUTHOR]

A novel strategy of dual system activation is developed to synthesize the nitrogen-doped biomass-derived carbon with hierarchically porous structure for high-performance lithium-ion storage properties. [Display omitted] Active biomass-derived carbons are brought into focus on boosting high-performance lithium storage. However, their low electric conductivity and poor ion diffusion kinetics during the lithium storage reactions remain confusing topics. This study demonstrates a novel and effective strategy of dual system activation process to construct the nitrogen-doped biomass-derived carbon with hierarchically porous architecture (HNBC), which is composed of the three-dimensional porous networks connected by carbon nanorods and the flake-like edges constructed by carbon nanosheets. A large amount of nitrogen doping can improve the conductivity and facilitate the charge transfer during charging/discharging, while the hierarchically porous structure can decrease the diffusion path for lithium-ion transport, enabling fast diffusion and charge-transfer dynamics. The HNBC electrode displays a high lithium-ion storage capacity of above 1392 mAh g−1 at 0.1 A g−1 and superior stability. Moreover, the assembled asymmetric lithium-ion capacitor exhibits excellent cycling stability and delivers a high power density of 225 W kg−1 with an energy density of 186.31 W h kg−1. This dual system activation strategy may inspire the reasonable design of new-generation progressive carbon-based electrodes for high-performance lithium storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] The effect of the chemical component and microstructure, not to mention their facile modification, of the coating/wrapping carbon layer on the electrochemical performance of the Si/C composite anode in lithium ion batteries (LIBs) hasn't been actively explored although Si/C has been recognized as one of the most promising route for the high energy density LIBs. Herein we propose a novel nitrogen-plasma doping route to modify the top carbon film in an elaborately constructed layered Si/C composite anode. The electrochemical performance, e.g., the initial coulombic efficiency (CE), cycle stability and specific capacity of the composite anode is drastically improved by this plasma processing due to the increased kinetics of lithium ions. By means of the appropriate adjustment of the N doping ratio and N chemical configuration in the carbon layer through a N 2 /H 2 plasma processing, the lithium diffusion rate in the composite anode was memorably increased as the pseudocapacitance effects promoted. The optimized Si/C composite exhibits a high capacity of 1120.7 mA h g−1 and an initial CE of 80.8% at the current of 2 A g−1 after a long cycle of 1500, increasing by ~40% of specific capacity and ~29% of the initial CE. [ABSTRACT FROM AUTHOR]

The well-designed porous carbon coating offers an attractive advantage compared to the common carbon coatings, and hence the as-prepared CNT@SnO 2 @PC composite shows outstanding electrochemical performance. [Display omitted] In order to reduce the negative impact of the extra carbon coating on the electrochemical properties of the commonly sandwiched carbon nanotubes@tin dioxide@carbon (CNT@SnO 2 @C) composites, the external C coating has been designed as a porous carbon in this work. The well-designed porous carbon coating offers an attractive advantage compared to the common carbon coatings, namely, it can not only better mitigate the volumetric variation of SnO 2 by means of its spongy structure with better flexibility and rich free space, but also accelerate the lithium-ions diffusion by virtue of its open tunnel-like architecture. For this reason, this composite prepared here shows outstanding electrochemical performance stemming from the cooperative effect of inner CNT supporting and externally porous carbon coating, displaying 819.3 and 576.0 mAh g−1 at 200 and even 1000 mA g−1 after even 500 cycles, respectively. This surface engineering strategy may be valuable for enhancing the cyclical durability of other metal oxides with higher theoretical specific capacities. [ABSTRACT FROM AUTHOR]

[Display omitted] The current commercialized polyethylene (PE) separator has poor wettability and thermal stability which will seriously restrict the electrochemical performance and affect the safety of lithium ion battery. Herein, a porous hybrid layer coated separator with high thermal stability, good electrochemical performance and improved wettability was prepared by a template-free method via the synergistic effect between tetraethoxysilane (TEOS) and aramid nano fibers (ANFs) during the evaporation of solvent and the in-situ gelation of TEOS. The results show that the porous hybrid coating layers can enhance the thermal stability, wettability and electrolyte uptake of the separators. Moreover, the lithium ion transference number is also increased. As a result, the battery assembled with the composite separator exhibits enhanced electrochemical performance in terms of cycle stability and rate performance. When coupled with LiCoO 2 cathode, the capacity retention rate is as high as 96.0% after 100 cycles at 0.2C. [ABSTRACT FROM AUTHOR]

[Display omitted] • An organic molybdenum complex is firstly used to synthesize MoO 2 /NC nanocomposite. • The synthetic route is easy, green, and economical with a yeild of nearly 100% • The nanoparticles with ultra-small size facilitates the conversion reaction. • N -doped carbon increase the structural integrity and electrical conductivity. • MoO 2 /NC exhibits an excellent electrochemical performance for Li-ion storage. MoO 2 is a promising anode material for lithium-ion batteries, however, the lithiation of bulk MoO 2 is usually limited to addition-type reaction at room temperature, and the conversion reaction is hindered because of the sluggish kinetics. Herein, a nanocomposite of MoO 2 embedded in nitrogen-doped carbon (MoO 2 /NC) is synthesized through the in situ thermolysis of an organic molybdenum complex MoO 2 (acac)(phen) (acac = acetylacetone, phen = 1,10-Phenanthroline). Owing to the fact that [MoO 2 ]2+ can be strongly chelated by phen, the molybdenum source in the MoO 2 (acac)(phen) precursor is highly dispersed, leading to the formation of ultra-small MoO 2 nanoparticles in the nanocomposite, which can facilitate the conversion reaction. Moreover, the NC matrix can guarantee a high electrical conductivity and effectively accommodate the volume changes triggered by the conversion reaction. Consequently, the MoO 2 /NC nanocomposite exhibits outstanding electrochemical properties, including large reversible capacity of 950 mA h g−1 at 0.1 A g−1, high-rate capability of 605 mA h g−1 at 2 A g−1, and excellent cycling stability over 500 cycles as an anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The stacked Cu 2−x Se nanoplates with the interlayer spacing of ~1.8 nm were fabricated with the assistance of diethylenetriamine. Such unique nanostructures provide the 2D nanochannels for accelerating the Li-ion transport and buffering the volume change during charge-discharge process, endowing the excellent electrochemical performance. Transition metal chalcogenides are considered as promising alternative materials for lithium-ion batteries owing to their relatively high theoretical capacity. However, poor cycle stability combined with low rate capacity still hinders their practical applications. In this work, the Cu-N chemical bonding directed the stacking Cu 2−x Se nanoplates (DETA-Cu 2−x Se) is developed to solve this issue. Such unique structure with small nanochannels can enhance the reactive site, facilitate the Li-ion transport as well as inhibit the structural collapse. Benefitting of these advantages, the DETA-Cu 2−x Se exhibits high specific capacity, better rate capacity and long cyclability with the specific capacities of 565 mAh g−1 after 100 cycles at 200 mA g−1 and 368 mAh g−1 after 500 cycles at 5000 mA g−1. This novel DETA-Cu 2−x Se structure with nanochannels is promising for next generation energy storage and the synthetic process can be extended to fabricate other transition metal chalcogenides with similar structure. [ABSTRACT FROM AUTHOR]

• N, S co-doped V 2 CT x MXene was prepared and its structure was optimized. • N, S co-doped V 2 CT x MXene exhibited superior electrochemical performances for LIBs. • The lithium storage mechanism of N, S co-doped V 2 CT x MXene was investigated. As an emerging group of two-dimensional (2D) layered material, MXenes have received significant attention in the direction of energy storage. However, the restacking of MXene flakes severely hinders the ion transport within electrodes, which limits their application for lithium-ion batteries (LIBs). To address this issue, herein, we rationally designed and optimized the structure of N, S co-doped V 2 CT x MXene, which exhibits excellent electrochemical performance with a high reversible capacity of 590 mAh g−1 after 100 cycles at 0.1 A g−1 when used as anode of LIBs. Even at a high current density of 2 A g−1, a reversible capacity of 298 mAh g−1 is obtained after 300 cycles, which outperforms most of the V 2 CT x -based anode materials reported so far. The lithium-ion storage mechanism of N, S co-doped V 2 CT x MXene was studied by a series of characterizations. The results show that the significant improvement of electrochemical performance should be attributed to the facilitated charge transfer after N and S co-doping in V 2 CT x MXene, which can effectively improve the ion transfer kinetics during the lithiation-delithiation process. Furthermore, the expanded interlayer spacing of N, S co-doped V 2 CT x provides more active sites for the adsorption of lithium ions, promoting the insertion capacity of lithium ions. This work indicates that the N, S co-doped 2D V 2 CT x MXene should be a promising anode material for high-performance LIBs. [ABSTRACT FROM AUTHOR]

Li 2 O-2B 2 O 3 coated Li 4 Ti 5 O 12 anode with protected particle surface and fast ion transfer exhibit desired rate capability and cycling stability for lithium ion batteries. Li 2 O-2B 2 O 3 (LBO) ionic conductor with high conductivity plays an important role in boosting the rate performance and cycling stability of Li 4 Ti 5 O 12 (LTO) anode for lithium-ion batteries by preventing direct exposure of LTO to the electrolyte. Herein, the effect of LBO coating layer on lithium ion (Li+) storage performance is investigated in detail by adjusting the adding amount of LBO precursor dispersion. LTO coated with 2 wt% LBO achieves an optimum performance with a specific capacity of 172.9 mA h g−1 at a current density of 0.1 A g−1, an improved rate capability (specific capacity of 127.9 mA h g−1 is maintained when the current density is 20 times than 0.1 A g−1) and a remarkable cycling stability (capacity retention of 94.2% after 4000 cycles at 2.0 A g−1). These LBO-LTO composites are competitive and promising candidates for electrochemical energy storage and other applications. [ABSTRACT FROM AUTHOR]

CaMnO 3 , a perovskite-type material, has been introduced as a novel anode material for lithium ion batteries, and its electrochemical performance at different temperatures is systematically investigated. The as-prepared CaMnO 3 material exhibits a high specific capacity, favorable rate performance and excellent cycling stability. The CaMnO 3 anode could deliver a high specific capacity of 102.5 mAh g-1 after 500 cycles at a current rate of 0.1 A g-1. Lithium ion batteries are attracting ever increasing attention due to their advantages of high energy/ power density, environmental friendly, lifetime and low cost. As a star in the field of materials and energy, perovskites have received extensive attention due to their attracting physical and chemical properties. Herein, CaMnO 3 , one material from the perovskite family is introduced as a novel anode material for lithium ion batteries, and its electrochemical performance at different temperatures is systematically investigated. CaMnO 3 has been synthesized using a liquid phase synthesis method followed by high temperature calcination. The as-obtained CaMnO 3 exhibits an initial high discharge capacity of 708.4 mAh g−1, superior rate capability and stable cycling performance at room temperature, the specific capacity is 102.5 mAh g−1 after 500 cycles at a current density of 0.1 A g−1. Additionally, at an extreme temperature of 0 °C, the discapacity can reach 138.2 mAh g−1 at a current density of 0.05 A g−1. At high temperature of 50 °C, the reversible discharge capacity is up to 216.5 mAh g−1under the same condition. It is believed that this contribution may lay the foundation for the application of perovskites in other rechargeable batteries and energy storage devices. [ABSTRACT FROM AUTHOR]

The Co 0.85 Se nanosheets with the interlayer spacing of ~1.0 nm on N-doped carbon nanosheets were fabricated with the assistance of diethylenetriamine. Such unique nanostructures provide the more channels for accelerating the Li-ion transport and buffering the volume change during charge-discharge process, endowing the excellent electrochemical performance. Co 0.85 Se nanosheets assembled layer by layer on N-doped carbon nanosheets (NC@Co 0.85 Se) are designed and fabricated through a facile solvothermal process. The hexamethylenetetramine as the solvent and complexing agent promotes the accumulation of Co 0.85 Se layer by layer. The long chain diethylenetriamine between the Co 0.85 Se nanosheets provides buffer space and nanochannels for accelerating the Li+ transportation. The N-doped carbon nansheets in NC@Co 0.85 Se provide effective conductive network during charge-discharge process. As an anode material for lithium-ion batteries, the NC@Co 0.85 Se nanocomposites deliver a high specific capacity of 636 mAh g−1 after 100 cycles at current density of 200 mA g−1, and 399 mAh g−1 for 500 cycles at high current density of 5000 mA g−1. [ABSTRACT FROM AUTHOR]

La 2 O 3 nanocoating endows LiNi 0.5 Mn 1.5 O 4 with a stable structure, thin SEI layers and fast lithium ions diffusion, boosting the lithium ion storage performance. • The cycling performance of LiNi 0.5 Mn 1.5 O 4 is highly enhanced by La 2 O 3 coating. • Voltage fade is introduced to evaluate the voltage stability of LiNi 0.5 Mn 1.5 O 4. • The effects of La 2 O 3 coating contents are systematically investigated. • The modified LiNi 0.5 Mn 1.5 O 4 possess a stable structure, thin SEI layers and fast lithium ions diffusion. In this work, a conformally interfacial nanocoating strategy is introduced to enhance the lithium ion storage performance of LiNi 0.5 Mn 1.5 O 4 (LNMO). Stable cycling of LNMO is achieved through La 2 O 3 coating at both room and elevated temperatures. A series of La 2 O 3 -coated LNMO composites with various coating contents ranging from 0 to 3 wt% is prepared, and their electrochemical behaviors are systematically investigated. Among them, the 2 wt% La 2 O 3 -coated LNMO cathode presents the best comprehensive lithium ion storage performance; for instance, it retains more than 75% capacity retention after 500 cycles at room temperature and 93% capacity retention after 50 cycles at an elevated temperature of 55 °C with 1C rate. Moreover, the modified samples show more stable plateau potential than the pristine one during the cycling process. It is believed that the introduction of the La 2 O 3 nanocoating layer can effectively suppress side reactions between electrode and electrolyte, thus maintaining stable structure of electrode material and reducing polarization during cycling. Our work provides an effective approach to improve the electrochemical stability of LNMO high-potential cathode for future large-scale applications of enhanced lithium ion batteries with high energy density and long cycle life. [ABSTRACT FROM AUTHOR]

A universal strategy to prepare heteroatom doped echinus-like porous carbon spheres as advanced anode for lithium ions battery has been developed. This study proposed a facile method to prepare echinus-like porous carbon spheres (PCS) with different heteroatom doping for lithium ions battery (LIBs). A metal-organophosphine framework (MOPF) was synthesized by employing riboflavin sodium phosphate as an organic ligand to conjugate with metal ions and then carbonized at mild temperature, leading to the formation of heteroatom doped PCS (H-PCS). As a result, (N, P) co-, (N, P, Ni) tri-, (N, P, Co) tri- and (N, Ni, Co, P) tetra-doped PCS were obtained to examine the insight into lithium-ion storage behavior of H-PCS. It was found that the specific surface area, pore texture and structural defects of H-PCS were dependent on doping of heteroatoms as well as the charge transfer resistance and Li-ion diffusion coefficient. Significantly, the redox reaction potential during the charge/discharge could be mediated upon the doping. Thus, when evaluated as anode for LIBs, the (N, Ni, Co, P) tetra-doped PCS exhibited highly reversible capacity of 680 mAh g−1 at 0.1 A g−1, excellent rate capability (115.9 mAh g−1 at 1.0 A g−1) and superior cycling performance (399.6 mAh g−1 at 0.1 A g−1). Moreover, the cyclic voltammogram measurements demonstrated that the doping of metal atoms was favorable for improving the capacitive contribution of surface limited diffusion. Thus, this work highlighted the importance of HCP with defined doping which could be considered as one of the prominent candidates for high-performance LIBs' anode. [ABSTRACT FROM AUTHOR]

Hierarchical porous chromium niobium oxide (Cr 0.5 Nb 24.5 O 62) microspheres are prepared by a facile one-step solvothermal method and demonstrated with noticeable lithium ion storage performance with superior high-rate capability (199 mAh g−1 at 20C) and good cycling stability. • Construct hierarchical porous Cr 0.5 Nb 24.5 O 62 microspheres as anodes. • Hierarchical porous Cr 0.5 Nb 24.5 O 62 microspheres show high capacity. • Hierarchical porous structure is favorable for fast ion/electron transfer. Controllable fabrication of advanced electrode materials is critical for the development of lithium ion batteries (LIBs). Herein, for the first time, we report novel hierarchical porous chromium niobium oxide (Cr 0.5 Nb 24.5 O 62) microspheres prepared by a facile one-step solvothermal method. The as-prepared Cr 0.5 Nb 24.5 O 62 microspheres present 3D hierarchical porous structure consisting of cross-linked nanoparticles, high electronic conductivity and large specific surface area. Accordingly, the Cr 0.5 Nb 24.5 O 62 microspheres show noticeable lithium ion storage performance with superior high-rate capability (199 mAh g−1 at 20C) and good cycling stability with a capacity retention of 95% over 1000 cycles, much better than the bulk Cr 0.5 Nb 24.5 O 62 and TiNb 24 O 62 counterparts. Our work demonstrates a new high-rate electrode material for high-power energy storage. [ABSTRACT FROM AUTHOR]

Electric vehicles have very strict requirements for lithium ion batteries (LIBs). However, the commercial polyethylene (PE) separators cannot meet the demands of high safety and electrochemical performance for LIBs. This work aims to enhance the electrochemical and safety performance of LIBs by coating the separator with multifunctional particles. First, the colloidal SiO 2 nanoparticles were etched by LiOH to form porous shell and lithium silicate (LSO) species simultaneously. Then, the SiO 2 nanoparticles with porous shell were coated on PE separator by dip-coating method in the presence of binder. The experiment results indicate that SiO 2 nanoparticles with porous shell can endow PE separator excellent thermal stability (thermal shrinkage is almost 0% at 150 ℃ for 30 min) and electrochemical properties (improved ionic conductivity and Li+ ion transference number). Moreover, the Li/LiCoO 2 cell employing the PE separator coated by SiO 2 with porous shell exhibits the best cycle life and C-rate performance. The discharge capacity retention of the cell assembled with LSO-SiO 2 @PE separator increase from 69% (cells assembled with pristine PE separator) to 86% after 100 cycles at 0.2C. [ABSTRACT FROM AUTHOR]

Graphical abstract Porous core-shelled Sn/Sn 4 P 3 @C composite is easily fabricated by electrochemically etching SnP alloy followed by covering the uniform carbon layer, which shows superior lithium-storage performances with higher specific capacity, much enhanced rate capability, as well as better cycling stability compared with pure porous Sn 4 P 3. The Sn/Sn 4 P 3 @C material holds promising application potential as an alternative anode in the lithium storage fields. Abstract Carbon encapsulated porous Sn/Sn 4 P 3 (Sn/Sn 4 P 3 @C) composite is conveniently prepared by one-step electrochemical dealloying of Sn 80 P 20 alloy in mild conditions followed by growing one carbon layer. Controllable dealloying of the Sn 80 P 20 alloy results in the formation of bicontinuous spongy Sn 4 P 3 nanostructure with a part of residued metallic Sn atoms embedded in the porous skeleton. A uniform carbon layer is deposited on the nanoporous Sn/Sn 4 P 3 to prevent the nanostructure's pulverizing and agglomerating during lithium ion insertion/extraction. Upon double conductivity modification from metallic Sn matrix and carbon layer, the as-made composite displays superior lithium-storage performances with much higher specific capacity as well as better cycling stability compared with pure porous Sn 4 P 3. It offers a specific capacity of 837 mA h g−1 after 100 cycles at a rate of 100 mA g−1. Even after 700 cycles at the higher rate of 1000 mA g−1, the specific capacity still maintains as high as 589 mA h g−1. The Sn/Sn 4 P 3 @C material possesses promising application potential as an alternative anode in the lithium storage fields. [ABSTRACT FROM AUTHOR]

Cobalt sulfide-based electrode materials were believed to have bright future in lithium-ion batteries (LIBs) application for their high theoretical capacity and excellent electrochemical stability. However, their relatively low electronic conductivity and the large volume variation during lithiation/delithiation processes usually result in low rate capability and short cycling life. Herein, a novel mesoporous Co 1-x S/N,S-codoped carbon (Co 1-x S/N,S–C) composite was prepared by direct pyrolysis of a cobalt-2-mercaptobenzothiazole (CoMBT) complex. High-content (91.14 ​wt%) and ultrafine (∼10 ​nm) Co 1-x S nanocrystals were in-situ generated and composited with high conductive N,S-codoped carbon. The Co 1-x S/N,S–C demonstrates superior Li+-ion storage performance, delivering high discharge capacities of 1207 ​mAh g−1 at 200 ​mA ​g−1 after 50 cycles and 425 ​mAh g−1 at 5 ​A ​g−1 after 1000 cycles. [Display omitted] • A metal-organomecapto complex derived strategy was developed. • A novel mesoporous Co 1-x S/N,S-codoped carbon composite was prepared. • The composite exhibits superior lithium storage performance. [ABSTRACT FROM AUTHOR]

Abstract: In this manuscript, porous Co3O4 nanorods are prepared through a two-step approach which is composed of hydrothermal process and heating treatment as high performance anode for lithium-ion battery. Benefiting from the porous structure and 1-dimensional features, the product becomes robust and exhibits high reversible capability, good cycling performance, and excellent rate performance. [Copyright &y& Elsevier]

Na 3 Fe 2 (PO 4) 2 F 3 has been synthesized under mild hydrothermal conditions. The structure of Na 3 Fe 2 (PO 4) 2 F 3 has been solved using single-crystal X-ray diffraction and the phase purity has been evaluated by Rietveld refinement from high resolution synchrotron powder X-ray diffraction data. Both methods establish the accuracy of P 4 2 / mnm space group and synthesis of so called beta 2 -polymorph. Room temperature 57Fe Mössbauer spectroscopic studies confirm 3+ oxidation state of the compound. The electrochemical properties have been investigated with respect to Li- and Na-ion batteries. Galvanostatic charge-discharge studies indicate that up to ~0.6 lithium ions and only ~0.4 sodium ions per Fe can be inserted at an average voltage of 2.82 and 2.42 ​V with respect to Li+/Li and Na+/Na in lithium and sodium ion batteries, respectively. The cycle-life studies indicate that Li-ion batteries show very stable capacity retention over long cycles while Na-ion batteries tend to lose capacity after ~35 cycles at C/5 rate. Na 3 Fe 2 (PO 4) 2 F 3 has been synthesized under mild hydrothermal conditions. The disordered sodium ions are located in the large cavity formed in the intersection of a - and b -axes of the three-dimensional structure of Na 3 Fe 2 (PO 4) 2 F 3. Reductive insertion of Na+ and Li+ ions have been carried out on this material of which Li-ion electrochemistry is reported here for the first time. Image 1 • Hydrothermal synthesis of Na 3 Fe 2 (PO 4) 2 F 3. • Cathode for Na-ion batteries. • Cathode for Lithium ion batteries. • Single-crystal structure of Na 3 Fe 2 (PO 4) 2 F 3. [ABSTRACT FROM AUTHOR]

A novel process for recycling of spent LiCoO 2 cathode materials has been developed. The novel process comprises an ultrasonic enhanced leaching and one-step regeneration of LiCoO 2 materials with spray drying method. The ultrasonic is novelly applied for effectively improving leaching process of spent LiCoO 2 materials in the system of DL-malic acid and H 2 O 2. The leaching efficiencies of 98.13% for Li and 98.86% for Co were presented under the optimal condition of 1.5 mol/L DL-malic acid with 3 vol% H 2 O 2 , the solid/liquid ratio of 4 g/L, ultrasonic power of 95 W, temperature of 80 °C and leaching time of 25 min. Based on kinetic analysis, the ultrasonic enhanced leaching process is mainly controlled by the diffusion control model. Meanwhile, the product of Co(C 4 O 5 O 5) 2 formed on particles surface of spent LiCoO 2 materials during ultrasonic enhanced leaching process, which is provided from reaction mechanism analysis of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Finally, the regenerated LiCoO 2 materials are regenerated in one step by spray drying from leaching solution, which present good electrochemical performance. A green sustainable process of recycling spent LiCoO 2 by ultrasonic enhanced leaching and one-step regeneration is developed. Image 1 • The sustainable closure process for recycling of spent LiCoO 2 materials is developed. • Waste acid would not be output during the whole green process. • Ultrasonic is applied to improving the leaching of spent LiCoO 2 materials. • One-step regeneration of leachate is proposed for preparing new cathode materials. [ABSTRACT FROM AUTHOR]

The easy intercalation/deintercalation of Li+ ions is the key factor for the functionality of the layered Li x CoO 2 compound as a Li-ion battery cathode material. However, the hexagonal CoO 2 -layer piling in the Li x CoO 2 structure is prone to incorporate not only monopositively-charged lithium ions but also monopositive protons. Here we employ a hydrothermal acid treatment for a gradual (controlled by the treatment time) de-intercalation of Li+ ions and a subsequent intercalation of protons between the CoO 2 layers in Li x CoO 2. We demonstrate that the lithium-for-proton exchange reaction can be monitored by AAS for the Li-content, by XRD for the proton-containing phase formation, and by FTIR and TG for the appearance of specific features indicative of the incorporated protons. With XPS we verify that upon the lithium-for-proton exchange the valence of cobalt remains the same, i.e. the proton incorporation compensates the positive charge loss due to the Li+-ion extraction. Finally, we show that essentially parallel lithium-for-proton exchange reactions occur also for Ni- and Mn-substituted Li(Co,Ni,Mn)O 2 samples, that is, for compounds that are highly relevant in current Li-ion battery technology. In acidic aqueous conditions Li(Co,Ni,Mn)O 2 compounds gradually release lithium ions and incorporate protons; this exchange reaction can be followed by TG and FTIR measurements. Image 1 • Acid treatment of LiCoO 2 releases Li+ cations and incorporates protons. • Ultimately this reaction yields trigonal H y CoO 2. • According to XPS Co valence remains constant upon the Li+-for-H+ exchange. • FTIR and TG can be used to monitor the incorporation of protons. • Similar Li+-for-H+ exchange reaction occurs also for Li(Co,Ni,Mn)O 2. [ABSTRACT FROM AUTHOR]

Layered LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM 622) cathode materials were synthesized through spray-drying method with different pressure treatments (0, 2, 3, 4 ​MPa). The results of XRD and XPS showed that the LiNi 0.6 Co 0.2 Mn 0.2 O 2 with 3 ​MPa treated presented lower level of cation mixing. And it also led to the increase of lithium interlayer spacing and the decrease of transition metal interlayer slab. It exhibited high specific capacity of 168 ​mA ​h g-1 at 0.5 ​C and 130 ​mA ​h g-1 at 10 ​C. After 150 cycles at 10 ​C, the retention also maintained above 85.1%. The sample treated with 3 ​MPa possessed superior lithium-ion diffusion ability and lithium ion diffusion coefficient were nearly three times than that of the untreated sample. The results illustrated that pressure-treatment was a practical approach for LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathodes to improve the electrochemical performance. The LiNi 0.6 Co 0.2 Mn 0.2 O 2 material treated with proper pressure reduced the level of cation mixing, expanded lithium interlayer spacing and improved the electrochemical performance at high current density. Image 1 • Pressure-treatments help to form uniformly particle and high tap-density material. • Li+/Ni2+ mixing of the cathodes decreased due to the pressure-treatment. • The cathodes with pressure-treatment delivered higher capacity property. • Cyclic performance at high current density of treated cathode was highly enhanced. [ABSTRACT FROM AUTHOR]

This study is aimed to recover the valuable metal ions from cathode materials of spent Li‒ion batteries (LIBs). Rapid microwave‒assisted dissolution process is investigated here to recover Li and Co from LiCoO 2 of spent LIBs. In the conventional method, about 6 h is required to extract about 90% of Li and Co using a mixture of citric acid (CA) and ascorbic acid (AA) at 80 °C. On the other hand, more than 85% of Li and Co was obtained in about 25 min by microwave (180 W)‒assisted dissolution. The dissolved Co and Li ions were precipitated, selectively: Li as LiHC 2 O 4 H 2 O or Li 2 CO 3 and Co as CoC 2 O 4 2H 2 O or Co‒citrate/ascorbate. The Co 3 O 4 was formed on heating the Co precipitate at 600 °C for 2 h. It is important to note that LiCoO 2 was re‒synthesized here by thermal decomposition of CoC 2 O 4 2H 2 O and LiHC 2 O 4 H 2 O at 750 °C for about 24 h. Thus, the microwave‒assisted hydrometallurgical method is found to be simple and rapid to recover Li and Co from spent LIBs. Image 1 • Microwave irradiation led to rapid dissolution of LiCoO 2 in mild organic acids. • More than 85% of Li and Co is recovered in about 25 min. • Co was precipitated as CoC 2 O 4 2H 2 O and Co‒citrate/ascorbate. • Li was precipitated as Li 2 CO 3 and pure LiHC 2 O 4 H 2 O. • LiCoO 2 was re-synthesized from CoC 2 O 4 2H 2 O and LiHC 2 O 4 H 2 O. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) has attracted enormous interest because of its prominent photocatalytic performance. Due to the planar π conjugation structure which should provide good binding energy for adsorption of metal atoms including lithium (Li) and sodium (Na), g-C 3 N 4 also possesses great application potential in ion batteries. Here, first-principles calculations are performed to investigate its application in lithium ion batteries (LIBs), focusing on the electric field effect on the Li storage. Our results revealed that Li adsorbed C 3 N 4 (Li–C 3 N 4) exhibits good modulation of its Li binding energy by applying external vertical electric field. The Bader charge analysis and charge density difference calculations provide a deep insight into the tunable Li adsorption to C 3 N 4 sheets. Our theoretical results suggest that C 3 N 4 is a suitable anode material for LIBs. • The physical mechanism concerning the good Li storage is unraveled.. • Strong ionic bonding between Li and C3N4 layer is demonstrated by charge density difference and Bader charge analysis. • Both the average charge and binding energies of Li exhibit good modulation by external electric field. • Non-monotonous variation of the binding energy of Li with electric field is revealed. [ABSTRACT FROM AUTHOR]