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Lithium-ion batteries (LIBs) has extensively utilized in electric vehicles and portable electronics due to their high energy density and prolonged lifespan. However, the current commercial LIBs are plagued by relatively low energy density. High-entropy materials with multiple components have emerged as an efficient strategic approach for developing novel materials that effectively improve the overall performance of LIBs. This article provides a comprehensive review the recent advancements in rational design of innovative high-entropy materials for LIBs, as well as the exceptional lithium ion storage mechanism for high-entropy electrodes and considerable ionic conductivity for high-entropy electrolytes. This review also analyses the prominent effects of individual components on the high-entropy materials' exceptional capacity, considerable structural stability, rapid lithium ion diffusion, and excellent ionic conductivity. Furthermore, this review presents the synthesis methods and their influence on the morphology and properties of high-entropy materials. Ultimately, the remaining challenges and future research directions are outlined, aimed at developing more effective high-entropy materials and improving the overall electrochemical performance of LIBs. [ABSTRACT FROM AUTHOR]

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]

[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]

A series of cathode materials, Li[Ni0.6Co0.12Mn0.2Fe0.08]1‐xCrxO2 (x=0, 0.02, 0.04, 0.06), are synthesized via the co‐precipitation method. Structural characterization shows that Cr3+ ions are successfully incorporated into the material structure and evenly dispersed on the surface of crystal particles with other metal elements. The Cr‐doped material shows a well‐defined hexagonal layered structure with less cation mixing, and the increase in interionic and interlayer distances is beneficial for the transport of lithium ions. Compared to the pure NCMFe phase, the cyclic and rate performances of the Cr‐doped quaternary materials have been significantly improved. Among them, the 4Cr material exhibits the best electrochemical performance. The capacity retention rate after 50 charge‐discharge cycles at 0.1 C was increased from 74.83 % to 87.32 %. The rate performance has also increased from 87.6 % to 92.69 %. The Cr‐doped cathode can reduce the charge transfer resistance and enhance the stability of the layered structure, which results in outstanding electrochemical performance of the Cr‐doped cathode. CV and EIS tests were conducted on materials with various Cr doping levels, further confirming that Cr doping can reduce the degree of polarization in electrode materials, enhance charge and discharge reversibility, and reduce the charge transfer resistance of materials. [ABSTRACT FROM AUTHOR]

Lithium Iron Phosphate (LiFePO4) microstructures have been synthesized using the sol-gel process. One-dimensional (1D) LiFePO4 microstructures were fabricated using tissue paper as a template under different temperatures to form pure phase microstructures. XRD analysis confirmed the single phase nature of orthorhombic olivine-structured LiFePO4 with Pnma space group. SEM analysis authenticated the formation of 1D LiFePO4 microstructures along with some clusters of particles. LiFePO4-multi-walled carbon nanotubes (MWCNT) freestanding sheets were prepared using a tape-casting process. Further, the electrochemical properties of LiFePO4-MWCNT freestanding sheet were analyzed through electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge analysis. [ABSTRACT FROM AUTHOR]

In this investigation, a lithium-free cathode material, Na0.7MnO2.05–Na0.91MnO2, was synthesized by the solid phase method. The intercalation mechanism and partial phase transformation mechanism of NMO600 were clarified by in situ X-ray diffraction and impedance. The design of the heterostructure is favourable for improving the lithium ion storage of NMO600, which can deliver a discharge capacity of 83.12 mA h g−1 at 1 A g−1 and keep 61.71 mA h g−1 after 700 cycles. [ABSTRACT FROM AUTHOR]

Graphene encapsulation is an attractive surface‐coating technology that can simultaneously improve the rate capability and cycle stability of nickel‐rich LiNixCoyMn1−x−yO2 (NCM). Here, carbon encapsulation with the addition of polyethylenimine (PEI) and polyhedral oligomeric silsesquioxane (POSS), which can effectively suppress access to and generation of harmful factors in the electrolyte to maximize the rate performance and cycle stability of nickel‐rich NCM, is described. The PEI‐POSS/carbon layer not only facilitates electron and lithium‐ion transport on the NCM surface but also inhibits side reactions with the electrolyte during repeated electrochemical reactions. In addition, it provides mechanical support that suppresses the formation of microcracks related to anisotropic volume change of nickel‐rich NCM secondary particles and inhibits irreversible phase transitions on surface structures by mitigating electrolyte wettability. As a result, PEI‐POSS/carbon‐encapsulated NCM exhibits a higher rate capability (84 mAh g−1 at 5 C) and cycle stability (93.5% for 100 cycles at 1 C) compared with bare NCM (0 mAh g−1 at 5 C and 78.4% for 100 cycles at 1 C). In a cycle test at 45 °C, it achieves a capacity retention of 72.6% for 100 cycles at 1 C, which is a 323% improvement in performance over that of bare NCM (22.5%). [ABSTRACT FROM AUTHOR]

Lithium‐rich layered oxides (LROs) are one class of the most competitive high‐capacity cathode materials due to their anion/cation synergistic redox activity. However, excessive oxidation of the oxygen sublattices can induce serious oxygen loss and structural imbalance. Hence, a near‐surface reconfiguration strategy by fluorinating graphene is proposed to precisely regulate Mn3+/Mn4+ and O2−/(O2)n− redox couples for remarkably stabilizing high‐capacity LROs and realizing the simultaneous reduction of the lattice stress, regulation of the Mn metal at a lower charge state, and construction of 3D Li+ diffusion channels. Combining with a highly conductive graphene‐coating layer, the surface oxygen loss, transition metal dissolution, and electrolyte catalytic decomposition are suppressed. Benefiting from this synergy, the modified LROs disclose higher initial Coulombic efficiency and discharge‐specific capacity and improve cyclability compared with pristine LROs. Further, it is revealed that the F− impact becomes easier for the O sites at the lattice interface of C2/m and R3¯$\bar{3}$m to sufficiently buffer lattice stress. Moreover, lithium ions coupled to the doped F atoms at the lattice interface migrate to the Ni‐rich R3¯$\bar{3}$m lattice sites with lower migration energies. This consolidated understanding will open new avenues to regulate reversible oxygen redox of LROs for high‐energy‐density lithium‐ion batteries. [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]

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]

It is always a challenge to separate cathode materials and aluminum foil collector efficiently in the pretreatment process of spent lithium-ion batteries (LIBs) recycling. In this work, the effects of NaOH concentration, liquid-solid ratio, dissolution temperature, and time on the traditional NaOH dissolving pretreatment process were systematically studied. Under the optimal conditions, the traditional dissolving process shows a limited aluminum dissolution rate of 83.59%. Through characterization and thermodynamic analysis, the fact that the traditional dissolving process results in the dissolution loss of lithium (5.5%) has been proved. The lost lithium may come from the free lithium ion and SEI layer on the cathode surface. Furthermore, a green and facile ultrasonic-assisted-enhanced dissolving pretreatment method was proposed. The dissolution rate of aluminum increases from 83.59% to 94.8% under the optimal conditions of NaOH concentration of 10 wt%, liquid-solid ratio of 10:1 ml/g, dissolution temperature of 30°C, dissolution time of 60 min and ultrasonic power of 288 W. Due to the mechanical and cavitation effects of ultrasonic, the efficient separation of cathode materials and aluminum foil and the decomposition of binder PVDF are completed in one step, which reduces energy consumption and avoids HF gas emissions. [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]

Iron(II) fluoride (FeF2) is a promising candidate as the cathode material for lithium-ion batteries (LIBs) due to its quite high theoretical energy density compared with the commercial cathode materials like LiCoO2 and its abundance. However, the actual energy density of various FeF2 materials nowadays is lower than the theoretical one. The actual energy density is largely determined by its conversion process, in which the transportation and migration of lithium ion (Li+) and electron play a vital role. The completeness of the Li+ and electron transport determines the completeness of the conversion process and further determines the capacity, while the ease of Li+ migration determines the conversion potential. This review is divided into four parts to introduce the Li+ and electron transport, from the aspects of barrier, stability, constructing method, and influence factors, in various existing "FeF2 materials-electrolyte" systems. The four parts are Li+ and electron transport or Li+ migration within a FeF2 particle, electron transport between FeF2 particles, Li+ transport from the electrolyte to FeF2, and the amount of Li+ that can transport. Finally, several points on optimizing the "FeF2 materials-electrolyte" systems with superior Li+ and electron transport are proposed. [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]

In recent years, the driving range of electric vehicles (EVs) has been dramatically improved. But the large‐scale adoption of EVs still is hindered by long charging time. The high‐energy LIBs are unable to be safely fast‐charged due to their electrode materials with unsatisfactory rate performance. Thus it is necessary to summarize the properties of cathode and anode materials of fast‐charging LIBs. In this review, we summarize the background, the fundamentals, electrode materials and future development of fast‐charging LIBs. First, we introduce the research background and the physicochemical basics for fast‐charging LIBs. Second, typical cathode materials of LIBs and the method to enhancing their fast‐charging properties are discussed. Third, the anode materials of LIBs and the strategies for improving their fast‐charging performance are analyzed. Finally, the future development of the cathode materials in fast‐charging LIBs is prospected. [ABSTRACT FROM AUTHOR]

Capacity degradation and voltage fade of Li2MnO3 during cycling are the limiting factors for its practical use as a high-capacity lithium-ion battery cathode. Here, the simulated amorphisation and recrystallisation (A + R) technique is used, for generating nanoporous Li2MnO3 models of different lattice sizes (73 Å and 75 Å), under molecular dynamics (MD) simulations. Charging was carried out by removing oxygen and lithium ions, with oxygen charge compensated for, to restrain the release of oxygen, resulting in Li2−xMnO3−x composites. Detailed analysis of these composites reveals that the models crystallised into multiple grains, with grain boundaries increasing with decreasing Li/O content, and the complex internal microstructures depicted a wealth of defects, leading to the evolution of distorted cubic spinel LiMn2O4, Li2MnO3, and LiMnO2 polymorphs. The X-ray diffraction (XRD) patterns for the simulated systems revealed peak broadening in comparison with calculated XRD, also, the emergence of peak 2Θ ~ 18–25° and peak 2Θ ~ 29° were associated with the spinel phase. Lithium ions diffuse better on the nanoporous 73 Å structures than on the nanoporous 75 Å structures. Particularly, the Li1.00MnO2.00 shows a high diffusion coefficient value, compared to all concentrations. This study shed insights on the structural behaviour of Li2MnO3 cathodes during the charging mechanism, involving the concurrent removal of lithium and oxygen. [ABSTRACT FROM AUTHOR]

Cathode precursors of lithium-NMC 811 were synthesized by the coprecipitation method using two different nickel sources, namely mixed nickel–cobalt hydroxide precipitate (MHP) and nickel sulfate. The characteristics of the synthesized precursors were compared with the characteristics of the commercial NMC 811 cathode precursor obtained from the international market. The XRD analyses identified that the diffraction peaks of the three precursor materials were in close agreement to that of Li0.05Ni0.75Co0.1Mn0.1O2, with the figure(s) of merit (FoM) of 0.81, 0.88, and 0.9, respectively, for the synthesized precursor that used MHP as the source of nickel (SM-LNMCO-811), nickel sulfate as the source of nickel (SX-LNMCO-811), and the commercial precursor (K-NMC-811). The elemental analysis of the synthesized precursors revealed the Ni:Mn:Co mol ratios of 0.8:0.08:0.12 and 0.76:0.11:0.13 for SM-LNMCO-811 and SX-LNMCO-811, respectively. The SEM analysis revealed that SX-LNMCO-811 and K-NMC-811 showed a similar particle morphology with a spherical shape; the SM-LNMCO-811 exhibited an irregular particle morphology. The particle size analysis showed that SM-LNMCO-811 had the largest average particle size (285.2 μm) while K-NMC-811 and SX-LNMCO-811 samples had almost the same average values (i.e., 18.28 and 17.16 µm, respectively). The results of the charge–discharge measurement of the fabricated battery cylindrical cells with SM-LNMCO-811, SX-LNMCO-811, and K-NMC-811 as cathode materials showed the best discharge value of the SX-LNMCO-811 sample at 178.93 mAh/g with an initial efficiency of 94.32%, which is in line with the electrochemical impedance measurement results that showed the largest ion conductivity and lithium ion diffusion coefficient value of the SX-LNMCO-811 sample that utilized the synthesized nickel sulfate as the source of the nickel. [ABSTRACT FROM AUTHOR]

In the pursuit of enhancing the energy density of lithium-ion batteries, cathode prelithiation emerges as a pivotal approach, introducing additional irreversible active lithium ions to augment performance. Li 5 FeO 4 (LFO) stands out as an excellent option, boasting an impressive theoretical specific capacity and the additional advantages of cost-effectiveness in raw materials and low preparation cost. However, the impact of extra lithium incorporations on compositional changes at the electrode-electrolyte interface as well as on cell stability has impeded further researches. Herein, a Mn doping strategy is proposed and predicted by first-principles calculations to synthesize partially Mn-substituted Li 5.125 Fe 0.875 Mn 0.125 O 4 (LFMO). And the prelithiation with LFMO improved the interfacial composition of LiFePO 4 (LFP) batteries compared to LFO, achieving a charging capacity of 213 mAh∙g−1 in the first cycle at 0.05 C. The subsequent treatment demonstrated superior cycling stability, maintaining a discharge specific capacity as high as 155.3 mAh∙g−1 after 100 cycles at 0.2 C, and exhibiting a higher capacity retention in the full cell. These discoveries could contribute to enhancing the regulation of battery interface during the utilization of LFO, potentially promoting the development of cathode lithium additives. • First-principle calculations predict the feasibility of Mn-substituted Li 5 FeO 4. • Prelithiation with modified lithium additives triggers LiF formation at interfaces. • Mn Modified lithium additives improve the energy density and cycle stability. [ABSTRACT FROM AUTHOR]

• Uniformity and reduced agglomeration of LMFP/C materials prepared with PVP. • LMFP/C material with excellent electrochemical properties. LiMn X Fe 1-X PO 4 (X = 0.6) has excellent energy density and thermal stability, combining the excellent multiplicity performance of LiFePO 4 and the high operating voltage of LiMnPO 4. However, lower electronic conductivity and lithium ion diffusion rate are the main problems faced. We successfully synthesized LiMn 0.6 Fe 0.4 PO 4 with uniform particles by a solvothermal method using surfactant PVP as an anti-agglomeration agent. At the same time, we found that the concentration of PVP in the reaction mixture plays a crucial role in the controllable structure and morphology of LiMn 0.6 Fe 0.4 PO 4 , thus accelerating the de-embedding of lithium ions reached 145.2 mAh g−1 under 1 C test. Therefore, the high-performance LiMn 0.6 Fe 0.4 PO 4 /C nanomaterials synthesized by the solvothermal method are significant for developing and applying lithium-ion batteries. [ABSTRACT FROM AUTHOR]

• Significant reduction of surface residual lithium due to the reaction between alumina and residual lithium to form LiAlO 2. • Enhanced charge transfer kinetics with LiAlO 2 modification. • Significant increase in energy density of full cells with the addition of modified samples. The active lithium ions loss during the initial charge and discharge process of lithium ion batteries seriously hampers its increasement of energy density. Pre-lithiation, involving the pre-storage of active lithium ions prior to cycling, emerges as a promising and effective strategy to offset this loss. Li 6 CoO 4 has been identified as a candidate capable of releasing adequate lithium ions to compensate for such loss. However, its poor air stability renders it susceptible to side reactions in the atmosphere, leading to the formation of residual lithium and consequently affecting its electrochemical performance. In this study, we propose application of a lithium aluminate (LiAlO 2) coated onto the surface of lithium cobalt oxide (Li 6 CoO 4) to mitigate the presence of residual lithium. Meanwhile, with decreasing of residual lithium, the rate capability is also enhanced. The research results demonstrate that samples treated with this coating layer exhibit an enhanced energy density in the full cell, indicating the efficacy of this approach in optimizing the electrochemical performance of prelithiation additives. [ABSTRACT FROM AUTHOR]

Layered high-nickel LiNi 0.8 Co 0.1 Mn 0.1 O 2 is a promising candidate of the next generation cathode materials for lithium-ion batteries. However, severe cycling instability and fast capacity drop induced by anisotropic structured change restrict its wide application. To address these defects, the structure design of cathodes is conducted. Herein, a hierarchical layered LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode consisting of orderly stacking hexagonal nanosheets with exposed active {104} facets is successfully synthesized by an improved co-precipitation process and followed with a high temperature lithiation reaction. Benefiting from this unique texture, exposed active {104} facets with lower surface energy supply 3D barrier-free Li+ ion diffusion channels, significantly improving the efficiency of the Li+ diffusion. Moreover, the consistent arrangement of nanosheets in the manner of the {001} facets close attachment is beneficial to alleviate the stress caused by the anisotropic structured change. Thus, this cathode material presents both superior reversible capability (203.8 mAh g−1 at 0.1C, 184.5 mAh g−1 at 1 C, 173.0 mAh g−1 at 5 C and 161.3 mAh g−1 at 10 C) and stable cycling performance (capacity retention of 89.3% after 100 cycles at 1 C, 55.3% after 300 cycles at 5 C and 59.6% after 300 cycles at 10 C). Schematic of single crystal shape evolution of the cathode materials and the corresponding cycle performance of the NCM-3 sample at different rates. [Display omitted] • A hierarchical cathode material consisting of orderly stacking nanosheets with exposed active {104} facets was successfully synthesized. • The exposed active {104} facets with lower surface energy could supply barrier-free Li+ ion diffusion channels. • The consistent arrangement of nanosheets is beneficial to alleviate the stress and inhibit the pulverization of secondary particles. • The hierarchical cathode material presents both superior reversible capability and stable cycling performance. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of Na doping on the structure, electrical, and electrochemical properties of lithium-rich cathode material. Pristine Li1.2Ni0.13Mn0.54Co0.13O2 (LNMC) and Na-doped Li1.17Na0.03Ni0.13Mn0.54Co0.13O2 (Na-LNMC) layered lithium-rich/manganese-rich compounds are prepared by the sol-gel method. The structural and morphological characterization reveals that the Na doping leads to an ordered structure with regular cubic morphology and enlarged Li layer spacing. This enlargement facilitates the diffusion of lithium ion inside the bulk lattice. Electrochemical impedance spectroscopy (EIS) shows that doping by a small amount of Na (3 mol%) decreases the impedance by more than three orders of magnitude and enhances the diffusion of lithium ions in the same proportion. This remarkable improvement in the conductivity and diffusion coefficient of lithium ions of Na-LNMC improves its capacity retention. In addition, this structure and mode of preparation results in "U-shaped" capacity vs. cycle curves, similar to the curves observed for transition metal oxide electrodes, resulting in an exceptional cycle life, tested for up to 400 cycles at 2C. [ABSTRACT FROM AUTHOR]

N,N′-bis(4-pyridyl)-1,4,5,8-naphthalene diimide (NDI-py) and N,N′-bis(4-benzidine)-1,4,5,8-naphthalene diimide (NDI-bz) were intercalated into lamellar vanadium pentoxide (V2O5·nH2O) xerogels (VXG) in different quantities. Li+ electro-insertion-associated specific charge capacity was considerably improved for the composite electrodes towards pure VXG (125 mA h g–1 for NDI-py3 and 141 mA h g–1 for NDI-bz3 composites vs. 98 mA h g–1 for pure VXG, at 0.1 mA cm–2), even when bearing low imide amounts. Composites charge/discharge cyclability is also enhanced due to the presence of the imides, especially in the case of VXG/NDI-bz composite. Electrochemical impedance spectroscopy results proved that charge transfer at electrolyte/host matrix interface is the limiting step of the lithium ion electro-insertion. The present results are in agreement with the results obtained with N,N′-bis(4-aminophenyl)-1,4,5,8-naphthalene diimide (NDI-ph), and allow a systematic structure/property analysis of V2O5·nH2O/1,4,5,8-naphthalene diimides as cathode materials for Li+ batteries. [ABSTRACT FROM AUTHOR]

The Fe‐doped LiVPO4F/C cathode material was synthesized by a one‐step solid‐state reaction method. The effects of Fe doping content on the structure and electrochemical performance of LiVPO4F/C were investigated. X‐ray diffraction (XRD) analyses demonstrated that the appropriate addition of Fe3+ did not destroy the lattice structure of LiVPO4F/C. Scanning electron microscopy (SEM) showed that the surface of LiVPO4F/C is covered by a carbon film. The decreased grain size of the Fe‐doped LiVPO4F/C could shorten the ion transport path and thus improve the migration rate of lithium ions. X‐ray photoelectron spectroscopy (XPS) showed that the Fe ion exists in the Fe‐doped LiVPO4F/C as Fe3+ ion. At the discharge rate of 1 C, the initial discharge capacity and capacity retention rate of the LiV0.98Fe0.02PO4F/C after 500 cycles were 123.5 mAh/g and 88.6%, respectively. [ABSTRACT FROM AUTHOR]

The LiNi0.6Co0.2Mn0.2O2 (NCM) cathode material is highly potential for the wide application in lithium-ion batteries due to its moderate cost and high specific capacity. However, the problems of its poor cycling stability and rate performance need to be further solved. Designing a single-crystal nanostructure of the NCM materials is an effective strategy to increase the rate characteristics, however, the performance decay and safety issues are still there due to the irreversible side reactions and structure degradation. In this study, the single crystalline hexagonal nanosheets of NCM material have been prepared using a hydrothermal process, and various amounts of Al2O3 are further controllably coated on the surface of NCM. The results show that a suitable amount of Al2O3 coating is conducive to the formation of a better layered structure NCM with smaller cation disorder and leads to higher discharge capacity, rate performance and longer cyclic life than the pristine material, due to the stabilized layered structure of cathode materials, the alleviated electrode/electrolyte side reactions and the favored diffusion of lithium ions. [ABSTRACT FROM AUTHOR]

The high nickel ternary cathode materials LiNi 0.815 Co 0.15 Al 0.035 O 2 (NCA) have been widely used in Li-ion batteries due to their high energy density, low cost, and little environmental pollution. However, it suffers from rapid capacity degradation and poor charging rate. In this work, Ti4+ doping NCA cathode materials are prepared by the high-temperature solid-state method. The results show that 0.5%Ti-NCA has a lower cationic mixing degree and better cycling performance. The capacity retention rate of 100 cycles is 98.91% and 96.59% at current densities of 0.5 C and 1.0 C, respectively. The CV and EIS test results show that 0.5%Ti-NCA has lower polarization and higher lithium ion diffusion coefficient D Li +(8.43×10−14 cm2/S) after 100 cycles, while Pure-NCA only has 6.92×10−15 cm2/S, which effectively enhances the electrochemical properties of NCA cathode materials. • Ti4+ hinders the cross-layer migration of Ni2+ and further reduces the cation mixing. • The charge compensation function of Ti4+ makes it have excellent performances. • The diffusion rate of Li+ increases due to Ti4+ increases the lattice parameter c. [ABSTRACT FROM AUTHOR]

In the work, we have focused on the surface variations of the LiNi 0.90 Co 0.04 Mn 0.03 Al 0.03 O 2 induced by the lithium ion conductor Li 0.34 La 0.56 TiO 3 and over-lithiated oxide Li 2 NiO 2 double coverings. The influence of various covering materials on particles morphology, crystal structure and electrochemical properties have been explored. It is found that the Li 0.34 La 0.56 TiO 3 firm layer could reduce the catalytic decomposition of electrolyte and further maintain the stable particles morphology and crystal structure of cathode after long-term cycling. In addition, the Li 2 NiO 2 served as the lithium supplement additive could compensate the irreversible active lithium ions loss during cycling and then relieve the cyclic capacity attenuation. Comparatively, the cathodes after Li 0.34 La 0.56 TiO 3 coating deliver the obvious enhanced rate capability, superior discharging capacity at low temperature and more stable cyclic performance than those of pristine LiNi 0.90 Co 0.04 Mn 0.03 Al 0.03 O 2. Besides, the Li 0.34 La 0.56 TiO 3 and Li 2 NiO 2 co-coated sample demonstrates the superior safety performance and cyclic stability when applied in the pouch battery in comparison with the pristine cathode. [Display omitted] • Li 0.34 La 0.56 TiO 3 and Li 2 NiO 2 co-covering is adopted to enhance LiNi 0.90 Co 0.04 Mn 0.03 Al 0.03 O 2. • Li 0.34 La 0.56 TiO 3 layer could maintain the morphology and structure stability. • Li 2 NiO 2 could compensate the irreversible active Li+ loss. • Li 0.34 La 0.56 TiO 3 and Li 2 NiO 2 co-coated cathode delivers the superior safety and cyclic stability. [ABSTRACT FROM AUTHOR]

Kinetic limitations and interfacial instability are critical issues hindering the commercial application of single-crystal Ni-rich Co-free cathodes. Herein, the strategy of Y/W co-doping has been performed to achieve high electrochemical performance of single crystal LiNi 0.9 Mn 0.1 O 2 cathode. As a result, the Y3+ and W6+ co-doped sample presents an obvious promotion capacity retention of 82.1% at 1.0 C after 100 cycles, when compared to that of undoped sample (71.9%). Furthermore, even at 3.0 C, the co-doped sample displays a high specific capacity of 152.0 mAh g−1, while the value for the pristine is only 139.8 mAh g−1. XRD, TEM and XPS results clarify that the co-modification with Y3+ and W6+ cations can stabilize the crystal structure and reduce the Li+/Ni2+ mixing. The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) show that Y3+ and W6+ co-doping can decrease potential polarization and electrochemical impedance, thereby effectively improve the diffusion kinetics of lithium ions. This study provides a promising route to prepare advanced Ni-rich Co-free single crystal cathode materials for lithium-ion batteries. ● Constructed a stable single crystal cathode material of Y/W co-doping LiNi 0.9 Mn 0.1 O 2. ● Improved the diffusion kinetics of lithium ions by Y3+ and W6+ co-doping. ● Reduced the Li+/Ni2+ mixing of materials. ● Resisted the corrosion of the electrolyte and obtained a well ordered crystal structure. ● Enhanced electrochemical performances of single crystal Ni-rich Co-free cathode material. [ABSTRACT FROM AUTHOR]

Co-free Li-rich Mn-based layered oxides (LRMLOs) are attractive cathode materials for lithium-ion batteries due to their low cost, high energy density and environmental friendliness. However, they also suffer from the drawbacks of low initial Coulombic efficiency, rapid voltage fading and capacity decay, and poor rate performance as the general LRMLO cathode, which prevent their practical applications. In the present work, a multilayer surface coating composed of Li 2 B 4 O 7 /B 2 O 3 and a spinel heterostructure rich-in oxygen vacancies are in-situ formed at the surface of the Co-free LRMLO particles by a facile thermal reduction treatment with NH 4 B 5 O 8. The multilayer surface improves greatly the electron and ion conductivities, and plays significantly synergistic roles on suppressing oxygen release, reducing the dissolution of Mn and Ni elements, retarding the structure transformation from layered to spinel, and preventing the side reaction of the active material with electrolyte during cycling for the cathodes. As a result, the overall electrochemical properties of the cathodes are significantly improved. With an optimized addition of 10 wt% NH 4 B 5 O 8 , the initial Coulombic efficiency of the cathode is as high as 90.0%, and a capacity of 275 mAh g-1 is obtained at 0.1 C (1 C = 200 mA g-1) with the capacity retention of 98.5% after 100 cycles. A capacity of 194 mAh g-1 is maintained after 300 cycles at 1 C, with the capacity retention of 92.8%. A capacity of 117 mAh g-1 is obtained at a high rate of 20 C. In addition, the voltage fading during cycling is also greatly inhibited. The structure evolution of the cathode material during cycling is systematically investigated and the mechanism for the improved electrochemical properties is proposed. The present work provides a new surface structure design strategy and the method for enhancing the overall electrochemical performance of Co-free Li-rich Mn-based layered oxide cathodes. [Display omitted] • NH 4 B 5 O 8 is used for surface modification of Co-free Li-rich layered oxides. • A multifunctional surface structure is constructed through thermal treatment. • Electronic and ionic conductivities are significantly improved. • The overall electrochemical performance is significantly improved. [ABSTRACT FROM AUTHOR]

Single crystal nickel-rich cathodes have been widely studied in the field of lithium-ion batteries (LIBs) due to their high volumetric energy density and good structural/electrochemical stability. However, a larger particle size (∼ 5 µm) prolongs the diffusion path of Li+ and leads to poor rate performance. In this work, a modification strategy of Ti4+ doping was used to prepare single-crystal Ni-rich cathodes LiNi 0.88 Co 0.06 Mn 0.06 O 2 with good rate performance. Compared to the polycrystalline Ni-rich cathode, the modified cathodes will have wider lithium channels to strip and embed lithium ions more easily. Concurrently, the secure Ti-O bonds can not only maintain the transition metal layer but also inhibit the "air sensitive effect". After 100 cycles, the electrochemical performance shows that the modified cathodes with 1 at.% Ti4+ doping have a comparatively high original capacity of 193.8 mAh g −1 and an upgraded capacity retention of ∼ 93.6 % (2.8–4.3 V) at 1 C. A better rate performance (118.6 mAh g −1) can be achieved at 10 C. This discovery will provide a good research direction for improving the insufficiency of single crystal nickel-rich cathodes. [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]

LiNi 0.5 Mn 1.5 O 4 (LNMO) is a promising next-generation cathode material for high energy density lithium-ion batteries, but the application of LNMO is blocked because of its inherent side effects with electrolytes at high voltages, namely, serious Mn dissolution and capacity attenuation. A novel LiNi 0.5 Mn 1.5-x Sr x O 4 material (x = 0, 0.05, 0.1, 0.15, and 0.2) was successfully prepared using the sol-gel method, and the effect of varying in situ Sr2+-doping on the crystal structure, morphology, and electrochemical performance was researched. A series of characterizations showed that the Sr-doped LNMO structure contains less Mn3+, which enhances its cycling stability. In addition, Sr doping promotes morphological changes more remarkably. Accompanied by the appearance of (100) surfaces, the morphology of LNMO changes from an octahedron to a truncated octahedron. The (100) surface can effectively inhibit side reactions with the electrolyte and steady the structure at the working voltage, which also helps support Li+ transport kinetics. The Sr-doped LiNi 0.5 Mn 1.4 Sr 0.1 O 4 (expressed as LNMO-Sr0.1) cathode exhibits preeminent cycling stability, after 500 cycles at 1C, the capacity retention is 86.63 %. CV and EIS results show that the right amount of Sr doping efficiently reduces electrode polarization and charge transfer resistance and increases the Li+ diffusion coefficient. [Display omitted] [ABSTRACT FROM AUTHOR]

The implementation of high‐nickel layered oxide cathodes in lithium‐ion batteries is hampered by the inherent issues of formation of NiO‐like rock‐salt phase as well as residual lithium (e.g., LiOH, LiHCO3, and Li2CO3) on the surface. To overcome the challenges, here a rational strategy is presented of interdiffusion‐based surface reconstruction via dry coating and the design principles for identifying the optimum coating ions on a LiNi0.91Mn0.03Co0.06O2 (NMC91) cathode. Notably, the combined approach of theoretical screening, which involves the consideration of superexchange interactions among different oxidation states and density functional theory calculations, along with experimental analyses, which involve the characterization of the decrease in Ni content and residual lithium on the surface of NMC91, demonstrate the effective reduction in rock‐salt phase and residual lithium. Among the four ions investigated (Al, Co, Fe, and Ti), cobalt‐coated NMC91 is the most effective at reducing the rock‐salt phase and residual lithium by successfully reconstructing the surface of NMC91 and exhibits an excellent capacity retention of 85% in a full cell after 300 cycles at 30 °C. [ABSTRACT FROM AUTHOR]

Considering the poor electronic conductivity of the pure Li9V3(P2O7)3(PO4)2, we have successfully synthesized a series of Li9−xMgxV3(P2O7)3(PO4)2 solid solution by aliovalent metal Mg ion doping on Li site. Due to the introduction of extra electrons caused by partially substituting Li+ ions by Mg2+, the electronic conductivity of the Mg-doped Li9V3(P2O7)3(PO4)2 sample was improved from 3.20×10−7 (for pure sample) to 8.85×10−6 S cm−1 (for Mg-doped sample). However, the inactive Mg2+ occupied the Li+ site often prevent the diffusion of the lithium ions in the electrode material and excessive Mg doping will obviously deteriorate the electrochemical performance of the electrode material. Considering the combined effect of the electronic conductivity and the lithium-ion diffusion coefficient for the excellent electrochemical performance, the optimal Mg-doping amount is x = 0.01 in our experiment. Compared with the pure sample, the Li9−xMgxV3(P2O7)3(PO4)2 (x = 0.01) sample exhibited a significantly increased specific capacity at all density rates and the capacity retention, especially at high rates, almost keep 100%. In addition, using the in-situ X-ray diffraction (XRD) method, we explored the reaction mechanism of the Li9V3(P2O7)3(PO4)2 electrode material and observed the existence and reversibility of the new phase during charge/discharge process. [ABSTRACT FROM AUTHOR]

Intercalation and deintercalation of lithium ions in cathode materials are of principal to the operation of current rechargeable lithium ion batteries. The performance of lithium ion batteries highly relies on the active cathode material which includes cell potential, power/energy density, capacity, etc. An important issue in this class of material is to resolve the factors governing the electron and ion transport in olivine phosphate structure. In this class of material, there is still an open debate on the mechanism of charge transport including both polarons and lithium ions. On the one hand, this is due to the large disparity between the experimental results and the theoretical model predictions. On the other hand, this is also due to the lack of precise experimental measurement without any parasitic phases in a given cathode material. Here, we present the polaronic conduction in lithiated triphylite LiFePO4 (LFP) and delithiated heterosite FePO4 (FP) by means of broadband ac impedance spectroscopy over wide range temperatures and frequency. It is found that the LFP phase possess two orders of higher polaronic conductivity than FP phase despite having similar mobility of polarons in both phases. We show that the differences in the polaronic conductivity of two phases are due to the significant differences in concentration of polarons. It is found that the formation energy of polarons in individual phases is mainly determined by the corresponding defect state associated with it. The temperature dependent dc conductivity has been analyzed within the framework of Mott model of polaronic conduction and explored the origin of polaronic conduction mechanism in this class of material. [ABSTRACT FROM AUTHOR]

Generating oxygen vacancies is an effective way to improve the lithium-ion storage performance of V2O5. However, the mechanism has not been theoretically investigated. In this study, first-principle calculations were performed to study the effect of oxygen vacancy on electrochemical properties of γ-V2O5 as cathode material for lithium-ion batteries. γ-V2O5 with oxygen vacancy mole fraction of 1.67% shows an open circuit voltage about 0.1 V lower than that of the perfect γ-V2O5. Oxygen vacancies generates gap states, which is beneficial to the electronic conductivity of γ-V2O5 and γ-LiV2O5. In addition, the activation energies for lithium-ion diffusion along [010] in both γ-V2O5 and γ-LiV2O5 are increased by oxygen vacancy, which might lead to the decrease of diffusion coefficient. Our results will provide guidance for further improving the lithium-ion storage performance of γ-V2O5. [ABSTRACT FROM AUTHOR]

Cation‐disordered rocksalt (DRX) materials have emerged as a class of novel high‐capacity cathodes for Li‐ion batteries. However, the commercialization of DRX cathodes will require reducing their capacity decay, which has been associated with oxygen loss during cycling. Recent studies show that fluorination of DRX cathodes can effectively reduce oxygen loss and improve cycling stability; however, the underlying atomic‐scale mechanisms remain elusive. Herein, using a combination of electrochemical measurements, scanning transmission electron microscopy, and electron energy loss spectroscopy, the correlation between the electrochemical properties and structural evolution in Mn‐redox‐based DRX cathodes, Li1.2Ti0.4–xMn0.4+xO2.0‐xFx (x = 0 and 0.2) is examined. It is found that fluorination strongly suppresses structural amorphization and void formation initiated from the particle surface, therefore greatly enhancing the cyclability of the cathode. A novel rocksalt‐to‐spinel‐like structural transformation in the DRX bulk is further revealed, which surprisingly contributes to a gradual capacity increase during cycling. The results provide important insight for the design of novel DRX cathodes with high capacity and long cycle life. [ABSTRACT FROM AUTHOR]

FeSO4 has the characteristics of low cost and theoretical high energy density (799 W⋅h⋅kg−1 with a two-electron reaction), which can meet the demand for next-generation lithium-ion batteries. Herein, FeSO4 as a novel high-performance conversion-reaction type cathode is investigated. We use dopamine as a carbon coating source to increase its electronic conductivity. FeSO4@C demonstrates a high reversible specific capacity (512 mA⋅h⋅g−1) and a superior cycling performance (482 mA⋅h⋅g−1 after 250 cycles). In addition, we further study its reaction mechanism. The FeSO4 is converted to Fe and Li2SO4 during lithium ion insertion and the Fe|Li2SO4 grain boundaries further store additional lithium ions. Our findings are valuable in exploring other new conversion-type lithium ion battery cathodes. [ABSTRACT FROM AUTHOR]

Summary: The porous spherical structure neodymium‐doped LiMn1−xNdxPO4/C nanoparticles have been prepared through glycolic acid‐assisted sol‐gel method. The neodymium‐ion doping effect on the crystalline microstructure, crystal appearance, and electrochemical parameters of LiMnPO4/C cathodes have been detected by X‐ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), charge and discharge test, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) method. XRD patterns show that a proper amount of neodymium‐ion doping could not change the host crystal structure; combined with EDS spectra, we could conclude that Nd3+ has successful embedding into the lattice structure of LiMnPO4/C. SEM analysis shows that the LiMn0.94Nd0.06PO4/C sample has the uniform and fine particles diameter distribution in comparison with other doped samples. The electrochemical measurement results indicate that the LiMn0.94Nd0.06PO4/C has the initial discharge specific capacity of 155.2 mAh/g at 0.05 C discharge rate; after 200 cycles, the capacity value reduces slightly to 138.7 mAh/g, the capacity retention rate is maintained at 89.4%. The LiMn0.94Nd0.06PO4/C has high‐rate discharge performance with the specific capacity value of 128.0 mAh/g (10 C). The results conclude that a proper amount of neodymium‐ion doping ratio could effectively enhance the lithium‐ion diffusivity and improve high‐rate performance of LiMnPO4 cathode materials. [ABSTRACT FROM AUTHOR]

To synthesize and optimize stoichiometric Li(Ni 0. 84 Co 0.16) 1-x Al x O 2 (NCA, 0 < x < 0.1) cathode materials with enhanced structural stability, different contents of nano Al(OH) 3 powders are employed to co -calcine with home-made Ni 0. 84 Co 0. 16 (OH) 2 precursor and LiOH·H 2 O by ball milling and followed by being co -calcined at 750 °C for 15 h. The results characterized by energy dispersive spectrometer, X-ray diffraction, and transmission electron microscope demonstrate that the as-prepared stoichiometric LiNi 0. 81 Co 0. 15 Al 0. 04 O 2 (NC-A4) sample presents a slightly decreasing Al atom concentration from the surface to the core, a lowering cationic disorder degree of 1.69% and an enlarged interplanar distance of the (003) phase of 0.482 nm when the content of the doped nano Al(OH) 3 powders is up to 4% based on the precursor. Moreover, the coin cell assembled with NC-A4 can deliver an initial discharge specific capacity of 196.3 mAh g−1 and retain 170.7 mAh g−1 after 100 cycles at 1.0 C at 30 °C with a remarkable capacity retention of 95.5%. Even though at a high current density of 5.0 C , it can also present a superior rate capacity of 162.1 mAh g−1. The enhanced electrochemical performance of NC-A4 is primarily attributed to the significant improvement in the structural stability with trivalent Al ions doping, which can not only maintain a stable lattice structure during the lithiation/delithiation process, but also alleviate the increasement of polarization degree and R ct value. Hence, the presented method would be a simple and effective way to construct stoichiometric and high-performance NCA cathode materials with excellent structural stability for lithium ions batteries. [ABSTRACT FROM AUTHOR]

Lithium iron phosphate (LFP) has become one of the current mainstream cathode materials due to its high safety and low price. Most modification methods applied (e.g. ion doping, carbon coating and particle size restriction) are used to overcome its poor electronic and ionic conductivity. Here, the Y–F co-doped LFP/carbon (LFP/C) precursor was successfully synthesized using a high temperature solid phase method. The electronic conductivity of the material is enhanced by doping with F which induces the rearrangement of the PO43+ electron cloud, while the doping with Y introduces Li+ vacancies, thereby reducing the space resistance of Li ion diffusion, resulting in an overall enhancement of the ionic conductivity of the material. In addition, XRD refinement results show that Y and F doping leads to a weakening of the Li–O bond while also widening the lithium ion diffusion tunnel, thereby increasing the lithium ion diffusion rate. Therefore, this work has produced LFP/C-YF-2, which exhibits an ultra-high discharge specific capacity of 135.8 mAh g−1 at 10C, and a discharge specific capacity of 148.6 mA h g−1 without attenuation after 700 cycles at 5C. It is hoped that this high-capacity and high-rate cycling stability material will become a promising cathode material for applications in high-power electric vehicles and other equipment. [ABSTRACT FROM AUTHOR]

In this study, La was doped into the lithium layer of Li-rich cathode material and formed a layered-spinel hetero-structure. The morphology, crystal structure, element valence and kinetics of lithium ion migration were studied by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The La doped lithium-rich cathode material exhibited similar initial discharge capacity of 262.8 mAh g−1 at 0.1 C compared with the undoped material, but the discharge capacity retention rate can be obviously improved to 90% after 50 cycles at 1.0 C. Besides that, much better rate capability and Li+ diffusion coefficient were observed. The results revealed that La doping not only stabilized the material structure and reduced the Li/Ni mixing degree, but also induced the generation of spinel phase to provide three-dimensional diffusion channels for lithium ion migration. Moreover, the porous structure of the doped samples also contributed to the remarkable excellent electrochemical performance. All of these factors combined to significantly improve the electrochemical performance of the material. [ABSTRACT FROM AUTHOR]

Attributed to the realization of the multielectron transfers, with a stable 3D framework, Li9V3 (P2O7)3(PO4)2 is considered an excellent cathode material, which can reversibly extract/insert nearly 5 mol Li. However, the poor intrinsic electronic conductivity and the low lithium diffusion coefficient limited its practical electrochemical ability. Considering the poor intrinsic electronic conductivity of the pristine Li9V3(P2O7)3(PO4)2 compound, the introduction of one extra electron by replacing V3+ with aliovalent Mo4+ ions increases the concentration of the electronic charge carriers from Li9V3(P2O7)3(PO4)2 and thus improves the electronic conductivity. At the same time, the larger ionic radius of Mo4+ leads to the increasement of the cell volume of the Li9V3(P2O7)3(PO4)2 sample and thus facilitates Li+ transport into the structure. As a result, the electrochemical performances of the Li9V3(P2O7)3(PO4)2 were improved obviously by a small amount of Mo. Especially for the Li9V3-xMox(P2O7)3(PO4)2 (x = 0.02) sample, the electrode present the highest specific capacity herein and an excellent rate performance which is a promising cathode for lithium ion battery application. [ABSTRACT FROM AUTHOR]

The Ni-rich cathodes are considered as the next generation candidate cathode material of lithium-ion batteries due to the high-energy–density and environmentally friendly. Unfortunately, the cathodes are up against severe structure instability at the repeated charge/discharge process, resulting in the attenuation of voltage and capacity. Herein, we proposed a novel strategy with uniform Al and Ti cations co-doping of LiNi0.8Co0.1Mn0.1O2 cathode. The modification strategy not only stabilizes the vulnerable layered structure but also mitigate voltage/capacity attenuation at different cutoff voltages. As a result, the modified cathode with trace content of Al and Ti cations co-doping can broaden the lithium ions diffusion channels, mitigate the structural collapse, and unfavorable phase transformation to some extent. Specifically, the modified sample exhibits remarkable enhanced electrochemical performance in discharge capacity and voltage retention of 76.75%, 98.78% at 1 C after 200 cycles. Even though at elevated voltage, the modified sample shows improved cycle life with a capacity retention of 70.93% after 200 cycles. [ABSTRACT FROM AUTHOR]

Conformal carbon encapsulation, graphene coatings, HF scavenging, nickel-rich layered cathodes, polyethylenimine, polyhedral oligomeric silsesquioxane The PEI-POSS/carbon layer not only facilitates electron and lithium-ion transport on the NCM surface but also inhibits side reactions with the electrolyte during repeated electrochemical reactions. Uniform and Multifunctional PEI-POSS/Carbon Encapsulation for High-Rate Performance and Surface Stabilization of Nickel-Rich Layered Cathodes in Lithium-Ion Batteries (Adv. Funct. [Extracted from the article]

A novel carbon supported LiMn2O4 nanocomposite framework has been explored to resolve multiple barriers associated with lithium manganese oxide cathodes for aqueous LIB systems. Here, we have successfully synthesized an architecturally stable AlF3−LiMn2O4/rGO composite with improved electron transfer kinetics and CV peak currents proportional to the square root of scan rate. The synergy between graphene and aluminium trifluoride enhances the intrinsic electrochemical properties of pristine LiMn2O4 (LMO) and reduced Mn+3 dissolution. The unique composite effectively reduced Li+ diffusion distances with less polarization as it effectively accommodates the structural transformation during Li+ ion charge and discharge. The electrochemical interrogation revealed faster charge transportation and decrease in charge transfer resistance due to inhibition of the pronounced pile‐up of Li+ ions and undesired Mn3+ ions on the surfaces. The electrochemical performances were tested in LiNO3 aqueous electrolyte and the cell delivered a capacity of 90 mA h g−1 based on the total weight of the active electrode materials. This aqueous LIB cathode system provides a promising alternative for safe, cost‐effective and scalable energy storage with tolerance against misuse. [ABSTRACT FROM AUTHOR]

Micro-patterned Ni-rich LiNi 0·91 Co 0·06 Mn 0·03 O 2 cathode is successfully fabricated at little expense for superior electrochemical performances. The micro-patterned Ni-rich LiNi 0·91 Co 0·06 Mn 0·03 O 2 cathode delivers high discharge capacity of 211.5 mAh g−1, extraordinary rate performance of 81.3% even at high C-rate of 4.0 C, stable cycle performance of 77.3% after 80 cycles. It is attributed to that the micro-patterning enhance the lithium ion and electron diffusion via expansion of electrochemically active sites with maintaining structural stability. Consequently, it can be concluded that micro-patterning shows great promise in excellent electrochemical performances for next-generation lithium ion batteries. • M-NCM shows the highest initial discharge capacity of 211.5 mAh g−1. • M-NCM delivers the extraordinary rate capability (81.3% at 4.0 C). • M-NCM stabilizes the cycling performance (77.3% after 80 cycles). • M-NCM maintains R ct value after 80th cycle (15.2 Ω). [ABSTRACT FROM AUTHOR]

All‐solid‐state lithium ion batteries (LIBs) are ideal for energy storage given their safety and long‐term stability. However, there is a limited availability of viable electrode active materials. Herein, we report a truxenone‐based covalent organic framework (COF‐TRO) as cathode materials for all‐solid‐state LIBs. The high‐density carbonyl groups combined with the ordered crystalline COF structure greatly facilitate lithium ion storage via reversible redox reactions. As a result, a high specific capacity of 268 mAh g−1, almost 97.5 % of the calculated theoretical capacity was achieved. To the best of our knowledge, this is the highest capacity among all COF‐based cathode materials for all‐solid‐state LIBs reported so far. Moreover, the excellent cycling stability (99.9 % capacity retention after 100 cycles at 0.1 C rate) shown by COF‐TRO suggests such truxenone‐based COFs have great potential in energy storage applications. [ABSTRACT FROM AUTHOR]