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Solid-state lithium battery is considered as a promising solution to improve safety performance. However, huge interfacial resistance and polarization between cathode and solid electrolyte are still big challenges for further application. In this study, an improved cathode/Li6.4La3Zr1.4Ta0.6O12 garnet electrolyte interface with low resistance and reduced polarization is successfully constructed by introduced a Li6.4La3Zr1.4Ta0.6O12-C added hybrid PVDF-HFP-based buffer layer. The hybrid buffer layer provides ionic and electronic transport pathways simultaneously at the interface. With the improved interface, the LiFePO4 cathode in the solid-state battery using LLZTO electrolyte displays an increased Li+ diffusion coefficient of 3.42 × 10−12 cm2 s−1 and low charge transfer resistance of 345.2 Ω at 1st cycle. The LFP solid-state battery reaches an initial capacity of 152.2 mA h g−1 and, in particular, displays an outstanding cycle performance with a retention of 84.6% over 200 cycles at 0.5 C and an average columbic efficiency of 99.5%. [ABSTRACT FROM AUTHOR]

Synthesis of precursor Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 in regular sphere shape as nickel-rich cathode material for Li-ion batteries remains challenging. Here, we report that the morphology of Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 can be tuned by controlling the reaction conditions of co-precipitation. The effects of the concentration of NH 3 ·H 2 O, pH of reaction solution, and stirring speed were studied in detailed. Precursor Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 with outstanding spherical hierarchical structure was successfully prepared. The cathode material of LiNi 0.8 Co 0.1 Mn 0.1 O 2 was then synthesized based on the prepared Ni 0.8 Co 0.1 Mn 0.1 (OH) 2. It showed excellent crystal structure, morphology and electrochemical properties. Within the voltage range of 2.7–4.3V, the initial discharge specific capacity was 203.7mAh·g-1 and 198.8mAh·g-1 at rate of 0.1C and 0.2C (1C = 200 mA g-1, at 30°C), and the capacity retention were 94.4% and 88.0% for 100cycles and 200cycles (0.2C, at 30°C), respectively. [ABSTRACT FROM AUTHOR]

Hollow silica (H-SiO 2 ) spheres are prepared via a self-assembly approach without sacrificial templates. To address the poor electrical conductivity and mechanical stability problems of H-SiO 2 , carbon coating is adopted to modify the H-SiO 2 spheres through a facile solution-mixing method. In the obtained micron-level H-SiO 2 /C composite, the carbon coating layer can act as a mechanical support layer to maintain the structure stability of the H-SiO 2 spheres, while the inner hollow space can accommodate the volume expansion during cycling. Moreover, the N-doped carbon can provide a fast electron transfer channel for the H-SiO 2 /C electrode during lithiation/delithiation process, helping the electrode exhibiting significantly improved cycling and rate performance. The reversible capacity of the H-SiO 2 /C electrode after 400 cycles is 564.0 mA h g −1 at a current density of 200 mA g −1 , with a capacity retention of 88.3% as against the first cycle. The electrode delivers a reversible capacity of 423.1 mA h g −1 , 280.8 mA h g −1 and 190.3 mA h g −1 at the current density of 1 A g −1 , 3 A g −1 and 5 A g −1 , respectively. This work provides a facile strategy for the large-scale production of H-SiO 2 /C anode materials for LIBs. [ABSTRACT FROM AUTHOR]

Developing high-voltage Li ion batteries (LIBs) is an important trend to meet the requirement of high energy density battery. However, high voltage will cause a series of problems harming the cycle performance of LIBs at the same time. This work is to investigate the effect of inorganic substance Li 2 SiO 3 on the electrochemical performance of LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) cathode at high cutoff voltage of 4.6 V. XRD result shows that the structure of NCM622 cathode material is not affected by mixing Li 2 SiO 3 . However, XPS and EIS tests indicate that Li 2 SiO 3 has an evident influence on suppressing the decomposition of LiPF 6 and carbonate solvents at high voltage, reducing interfacial solid film impedance and modifying electrode/electrolyte interface. In addition, Li 2 SiO 3 retards the transition metal dissolution by consuming HF. Therefore, it enhances the electrochemical properties of the NCM622 cathode significantly. The highest discharge capacity increases to 191.7 mA h g -1 by mixing Li 2 SiO 3 , compared with the value of 180 mA h g -1 in the case of NCM622 cathode. The NCM622 electrode mixed with Li 2 SiO 3 also exhibits a better capacity retention of 73.4% after 200 cycles and a high rate capability at 20C with the value of 89 mA h g -1 , in contrast with 62.2% and 31 mA h g -1 attained in the NCM622 cathode. [ABSTRACT FROM AUTHOR]

High energy density lithium-ion batteries are eagerly required to electric vehicles more competitive. In a variety of circumstances closely associated with the energy density of the battery, positive electrode material is known as a crucial one to be tackled. Among all kinds of materials for lithium-ion batteries, nickel-rich layered oxides have the merit of high specific capacity compared to LiCoO 2 , LiMn 2 O 4 and LiFePO 4 . They have already become one of the most attractive candidates for the mainstream batteries in industries. In this work, the recent advances on three commonly concerned nickel-rich layered oxides are presented. The preparation, microstructure, electrochemical performances are focused, the modification including coating design as well as dopant selection is specially discussed in details, which is essential to enhance the durability and energy density of lithium-ion batteries. Additionally, the prospects and challenges are also systematically discussed, as well as the potential applications in the field of energy storage technologies. [ABSTRACT FROM AUTHOR]

Li 2 SiO 3 -coated LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode material has been synthesized and exhibit much better electrochemical performance than pristine LiNi 0.6 Co 0.2 Mn 0.2 O 2 at cut-off voltage 4.6 V. The as-prepared samples are characterized by X-ray diffraction, field emission scanning electron microscopy, field emission transmission electron microscope, and X-ray photoelectron spectroscopic. The results show that the coating-layer Li 2 SiO 3 is not incorporated into the LiNi 0.6 Co 0.2 Mn 0.2 O 2 host structure and coated well on the surface of the active material. The sample coated with 3 mol. % Li 2 SiO 3 delivers a capacity of 168 mAh g −1 at 0.2 C after 100 cycles, and remains 85.5% of the first discharge capacity. The capacity retention at 1C is 73.6% after 100 cycles and the first discharge capacity reaches 158 mAh g −1 at 10 C. This superior performance is attributed to the coating layer which restrains the side reactions at electrode/electrolyte interface and enhances structure stability, meanwhile, it can decrease the electrode polarization because it is an excellent Li + -ion conductor. [ABSTRACT FROM AUTHOR]

Gelatin is alternatively adopted as the binder to modify Si anode coupling with its carbonization treatment. The binder can provide good bonding and uniform dispersion of the particles besides its environmental benignancy. Importantly, the carbonized binder containing nitrogen will be advantageous to the electrical conductivity of the electrode. In addition, some spaces are formed in the electrode due to the decomposition and shrinkage of the gelatin binder during heat-treatment, which may facilitate electrolyte penetration and accommodate volume change during cycling. All these merits make contribution to the good electrochemical performance of the modified Si electrode. It exhibits a reversible capacity of 990.3 mA h g −1 after 70 cycles at a current density of 100 mA g −1 and 904 mA h g −1 after 100 cycles at 400 mA g −1 . [ABSTRACT FROM AUTHOR]

Nano-structured Li 4 Ti 5 O 12 crystals coated with carbon layer are in situ synthesized via one-step liquid process taking advantage of low-cost sucrose as carbon source in this work. The as-prepared LTO/C particles present much larger specific surface area (58 m 2 g −1 ) relative to the value of pure LTO, with a size around 13 nm in average. Its electronic conductivity of 6.56 × 10 −4 S cm −1 is over three orders of magnitude higher than the pure one. The composite anode displays a distinguished electrochemical charge/discharge performance, especially, quite high rate capability along with a stable cyclability. It delivers the initial discharge specific capacities of 156.7 and 142.1 mA h g −1 at 40C and 60C respectively, and remains the values of 114.2 and 98.1 mA h g −1 after 200 cycles. Furthermore, a capacity of 132.8 mA h g −1 is delivered even at an 80C rate and the value of 82.7 mA h g −1 can be maintained after 200 cycles. The ultrafast charge/discharge capability may be attributed to the shorten Li + transport path in the nanosized composite and the enlarged access area with electrolyte. Additionally, the carbon coating may provide an effective conductive network among the particles promoting charge transfer. [ABSTRACT FROM AUTHOR]

Abstract: Li-rich layered composite Li[Li0.2Ni0.2Mn0.6]O2 is prepared by a novel approach in which carbon felt acts as a carrier for synthesis reaction. The as-prepared material is characterized by SEM, ICP and XRD, its electrochemical performance is also examined with galvanostatic charge/discharge and CV measurements. It is showed that the facile process controls effectively the particle growth (in size around 100–200 nm) of the composite and its chemical composition. The as-prepared material shows a high initial discharge capacity about 288 mAh g−1 when charged to 4.8 V, and a retained value of 246.8 mAh g−1 in the 40th cycle. The crystalline structure of the composite is simulated further by Material Studio. It is revealed that the composite has a compatible layer structure merged by Li2MnO3 and LiNi0.5Mn0.5O2, which makes substantial contribution to the cycleability of the electrode. In addition, the lithiation/delithiaion properties including charge transfer resistance and lithium ion diffusion coefficient are studied with electrochemical impedance spectra. [Copyright &y& Elsevier]

Abstract: A novel synthesis of Si/mesoporous carbon (MC) composite is investigated in this work, as well as its lithium storage ability as an anode material. Nanosized Si particles are deposited in the pores of carbon matrix via magnesiothermic reduction, the content of Si is around 43wt.% in the composite. The electrochemical performance of the composite electrode is effectively improved due to the buffering effect of carbon matrix and its Si-embedded structure. It exhibits an initial reversible capacity of 1220.9mAhg−1, and an modified cycleability having the capacity of 594mAhg−1 in the 50th cycle. Additionally, the good rate capability of the electrode can be ascribed to the rich porous channels and the good conductive network of mesoporous carbon. [Copyright &y& Elsevier]

Abstract: In this study, a prediction model based on artificial neural network is constructed for surface temperature simulation of nickel–metal hydride battery. The model is developed from a back-propagation network which is trained by Levenberg–Marquardt algorithm. Under each ambient temperature of 10°C, 20°C, 30°C and 40°C, an 8Ah cylindrical Ni–MH battery is charged in the rate of 1C, 3C and 5C to its SOC of 110% in order to provide data for the model training. Linear regression method is adopted to check the quality of the model training, as well as mean square error and absolute error. It is shown that the constructed model is of excellent training quality for the guarantee of prediction accuracy. The surface temperature of battery during charging is predicted under various ambient temperatures of 50°C, 60°C, 70°C by the model. The results are validated in good agreement with experimental data. The value of battery surface temperature is calculated to exceed 90°C under the ambient temperature of 60°C if it is overcharged in 5C, which might cause battery safety issues. [Copyright &y& Elsevier]

Lithium is thought to be an excellent anode material for next-generation Li metal batteries (LMBs). However, some problems with lithium anodes often lead to serious safety concerns and catastrophic failures due to the huge volume change, Li dendritic growth, and related side reactions. Therefore, in order to manufacture stable rechargeable batteries, the abovementioned serious problems must be effectively solved. In this paper, a three-dimensional N,P-doped silicon-containing lithium anode is designed and prepared by in situ metallurgy using low-cost Si3N4. The 3D stable composite anode (DLi/LiSix CA) was prepared by adding a small amount of Si3N4 to molten lithium to form N-doped silicon-containing lithium metal which was supported on a polyaniline modified carbon cloth (PMCC). The results show that the DLi/LiSix CA not only has high Li affinity but can also effectively inhibit lithium nucleation and lithium dendritic growth, so as to maintain good structural stability in the process of Li plating/stripping. The new lithium metal anode based on doping and 3D carbon cloth shows good cycling stability and low polarizability in both symmetrical and full cells. [ABSTRACT FROM AUTHOR]

In this work, pomegranate-like shell structured Si@C material with tunable inner-space is designed and synthesized through a self-assembly and excess reduction approach for the first time. Through adjusting the quantity of reactants, the ratio of shell thickness to inner space radius in the hollow structure is optimally tuned. Moreover, the process not only possesses high conversion yield (>90%) but also is environmentally friendly. In this architecture, the void space in the hollow structure and the mechanically constraining carbon layer outside the spheres can synergistically accommodate the huge volume changes during cycling. Combining these characteristics, the Si@C anode affords comprehensively excellent performance, such as a high reversible capacity of 1494 mA h g−1, outstanding cycling stability with the capacity retention over 100 cycles of nearly 97% at 100 mA g−1, 96% at 500 mA g−1 and over 200 cycles of about 92% at 1 A g−1, 85% at 2 A g−1 and superior rate performance with a reversible capacity of 908 mA h g−1 at a high current density of 2 A g−1. Significantly, the areal capacity of Si@C electrode is as high as 3.47 mA h cm−2 at a high mass loading of 2.32 mg cm−2. • Pomegranate-like shell structured Si@C material with tunable inner-space is designed. • The ratio of shell thickness to inner space radius in the hollow sphere is tuned. • The process not only possesses high conversion yield but also is eco-friendly. • Si@C enables superior cycling stability and high areal capacity at high mass loading. [ABSTRACT FROM AUTHOR]

It is important for the electrolytes to maintain and enhance the lithium ion battery electrochemical performance, and solvation of Li+ is a key parameter for the property of the electrolytes. The comparative study on Li+ solvation structures, energy, enthalpy, Gibbs free energy, infrared and Raman spectra in common organic electrolyte solvents is completed by density functional theory (DFT) method. The solvation reaction energy results suggest that the Li+ solvation priority order is propylene carbonate (PC) > ethylene carbonate (EC) > ethyl methyl carbonate (EMC) > diethyl carbonate (DEC) > tetrahydrofuran (THF) > dimethyl carbonate (DMC) > 1,3-dioxolane (DOL) > dimethoxyethane (DME) to form 5sol-Li+. It is also indicated that the most innermost solvation shell compounds formations by stepwise spontaneous solvation reaction are four cyclic solvent molecules and three linear solvent molecules combining one Li+ forming 4sol-Li+ and 3sol-Li+, respectively, at room temperature. Besides, the vibration peaks for C=O and C–O bonds in carbonate ester solvents-Li+ compounds shift to lower frequency and higher frequency, respectively, when the Li+ concentration increases in the solvation compounds. All Li–O stretching vibration peaks shift to higher frequency until forming 2solvent-Li+ complexes, and C–H stretching also shifts to higher frequency except for nDME-Li+ solvation compounds. The Raman spectrum is more agile to characterize C–H vibrations and IR is agile to C=O, C–O, and Li–O vibrations for Li+ solvation compounds. [ABSTRACT FROM AUTHOR]

Silicon‐based materials are among the most promising anode materials for next‐generation lithium‐ion batteries. However, the volume expansion and poor conductivity of silicon‐based materials during the charge and discharge process seriously hinder their practical application in the field of anodes. Here, we choose carboxymethyl chitosan (CMCS) as the carbon source coating and binding on the surface of nano silicon and hollow silicon dioxide (H−SiO2) to form a hierarchical buffered structure of nano‐hollow SiOx@C. The hollow H−SiO2 can alleviate the volume expansion of nano silicon during the lithiation process under continuous cycling. Meanwhile, the carbon layer carbonized by CMCS containing N‐doping further regulates the silicon's expansion and improves the conductivity of the active materials. The as‐ prepared SiOx@C material exhibits an initial discharge capacity of 985.4 mAh g−1 with the decay rate of 0.27 % per cycle in 150 cycles under the current density of 0.2 A g−1. It is proved that the hierarchical buffer structure nano‐hollow SiOx@C anode material has practical application potential. [ABSTRACT FROM AUTHOR]

Abstract Silicon (Si) is regarded as the most attractive anode for high-performance lithium-ion batteries due to its high theoretical specific capacity. Unfortunately, Si experiences significant volume changes, leading to severe capacity fading and poor cycling stability. Here, novel hierarchical void structured Si/PANi/C microspheres are designed and synthesized to tackle these problems. In this architecture, silicon nanoparticles (SiNPs) with conductive polymer conformal coating are homogeneously dispersed in a three-dimensional porous polymer framework which is partially carbonized. The void space in highly porous matrix is not only capable of accommodating volume expansion but also favorable for liquid electrolyte penetration, enabling extremely stable cycling performance and superior rate capability, along with high areal mass loading. The outside carbon layer containing nitrogen may help attain a stable solid electrolyte interphase (SEI) film. The resultant Si/PANi/C anode reaches the reversible charge capacity of 1470 mAh g−1 at 100 mA g−1 and the average capacity loss after 200 cycles is only 0.04% per cycle. Moreover, Si/PANi/C anode exhibits excellent rate performance of ∼790 mAh g−1 even at 1 A g−1 and its Coulombic efficiency increases to 99% after only 3 cycles. Remarkably, the reversible areal capacity is high with a value of 2.74 mAh cm−2 at a high mass loading of ∼1.9 mg cm−2. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) network structure Si/C anode with large pores is fabricated by using gelatin-PVA as carbon source. Silicon particles are embedded in the 3D network carbon skeleton. Gaussian calculation and FTIR test are employed to analyze the role of molecules interaction in forming the 3D network structure. The modified Si/C anode exhibits a reversible capacity of 830 mA h g after 100 cycles at 400 mA g, and a capacity of 810 mA h g at 1.6 A g and 521 mA h g at 3.2 A g. The 3D network structure with large pores benefits the electrolyte penetration, and the carbon coating layer avoids the direct contact of silicon particles with the electrolyte. The carbon layer can also help buffer the volume expansion of silicon, which is good to the cycling stability. All these aspects contribute to the enhanced electrochemical performance of the Si anode. [ABSTRACT FROM AUTHOR]

Sodium as the closest analogue of lithium in periodic table is attracting intense interest as a potential replacement, in the hope that Na+ offers similar intercalation chemistries in electrode hosts at much lower cost. Sodium‐ion battery is an alternative choice to meet the large‐scale electrical energy storage and also able to be used to store the electricity generated by solar cells and wind turbines as a green, renewable energy source. The use of solid electrolytes to replace the organic electrolyte is an alternative to improve the safety and avoid liquid leakage. The detailed and comprehensive research progress for sodium‐ion battery solid electrolyte is summarized. The recent research reveals that the chemical composition and crystal structure of electrolytes profoundly affects the cell performance in many aspects. The room temperature ionic conductivity for solid polymer electrolytes (SPEs) is generally lower than ≈10−5 S cm−1. Gel polymer electrolyte (GPE) yields acceptable ionic conductivity as the transition between liquid electrolyte and all‐solid electrolyte. There also has groundbreaking progress of inorganic solid electrolyte chemistries exhibiting superionic Na+ conductivities. However, their interphasial chemistries are the emphasis to break through. In the future, exciting breakthroughs in solid electrolytes and interphasial chemistries should be made in those fields. [ABSTRACT FROM AUTHOR]

Si/mesoporous carbon composite is prepared from a mixture of SiO2 powder, Mg powder, and mesoporous carbon heated in a tube furnace at 650 °C for 6 h under Ar. [ABSTRACT FROM AUTHOR]

[Display omitted] Due to the obvious benefits of abundant resources and low cost of sodium, sodium-ion batteries have enormous development potential and a broad market outlook in the field of large-scale energy storage and low-speed electric cars. Layered oxide cathode material is considered as one of the most promising cathode materials for sodium-ion batteries due to its high energy density, rich variety, simple synthesis method and low environmental pollution. However, the layered oxides of sodium-ion batteries suffer from instability in air storage and unstable electrochemical performance during cycling. This review summarizes surface and bulk structural evolution in air exposure and during cycling to reveal the relationship between structure evolution, charge transfer mechanisms and electrochemical performance, which is of great significance for designing advanced electrode materials. The strategies based on the degradation mechanisms for layered oxides cathode materials are also discussed for the future development and industrialized application. We hope that this review will provide a basis for an accurate understanding of the structural evolution of layered oxides and provide some inspiration for the design and development of electrochemical systems with excellent performance. [ABSTRACT FROM AUTHOR]

The development of large‐scale energy storage systems (EESs) is pivotal for applying intermittent renewable energy sources such as solar energy and wind energy. Lithium‐ion batteries with LiFePO4 cathode have been explored in the integrated wind and solar power EESs, due to their long cycle life, safety, and low cost of Fe. Considering the penurious reserve and regional distribution of lithium resources, the Fe‐based sodium‐ion battery cathodes with earth‐abundant elements, environmental friendliness, and safety appear to be the better substitutes in impending grid‐scale energy storage. Compared to the transition metal oxide and Prussian blue analogs, the Fe‐based polyanionic oxide cathodes possess high thermal stability, ultra‐long cycle life, and adjustable voltage, which is more commercially viable in the future. This review summarizes the research progress of single Fe‐based polyanionic and mixed polyanionic oxide cathodes for the potential sodium‐ion batteries EESs candidates. In detail, the synthesized method, crystal structure, electrochemical properties, bottlenecks, and optimization method of Fe‐based polyanionic oxide cathodes are discussed systematically. The insights presented in this review may serve as a guideline for designing and optimizing Fe‐based polyanionic oxide cathodes for coming commercial sodium‐ion batteries EESs. [ABSTRACT FROM AUTHOR]

Single-crystal nickel-high materials (ST-LNCMO) LiNi 0.6 Co 0.2 Mn 0.2 O 2 have been synthesized using a versatile hydrothermal method. The as-prepared samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and selected area electron diffraction (SAED). The results show that the sample annealed at an optimized temperature of 850 °C reveals uniform fine well-crystallized single-particles with diameters of ～800 nm. Electrochemical data demonstrate that the cell using this nickel-high material as the cathode exhibits excellent performance. The sample displays a high capacity of 183.7 mA h·g −1 at 36 mA·g −1 (0.2 C) and excellent cycling stability at different rates. It yields an initial discharge capacity of 153.6 mA h·g −1 at a rate of 10C-rate and a voltage of 2.8 V – 4.3 V. The sample also has an outstanding rate capacity at a high cut-off voltage (4.6 V). This superior performance is attributed to the merits of the single-crystal structure, which may be beneficial to the transportation of the Li + ion along the grain. [ABSTRACT FROM AUTHOR]

The submicron single crystals of LiCoPO 4 with 500 nm diameter are prepared by solvothermal method. The carbon coated sample is obtained using sucrose as carbon source under 650 °C subsequently. It is investigated that the solvent composition has an effect on the morphology and the electrochemical performance of the cathode material. The as-prepared samples are characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopic, dynamic light scattering, and Fourier transform infrared spectra. The electrochemical performance is evaluated by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The LiCoPO 4 /C cathode can reach an initial discharge capacity of 123.8 mA h g −1 at 0.1C, with a retention of 83% after 100 cycles. A discharge capacity of 84.9 mA h g −1 is still attainable when the rate is up to 2C. The good cycling performance and rate capability are contributed to the decrease of particle size along with the lower antisite defect concentration in the LCP crystals, and uniform carbon coating. [ABSTRACT FROM AUTHOR]

A delicate structure of graphitic carbon-encapsulated α-Fe 2 O 3 nanocomposite is in situ constructed via “Absorption–Catalytic graphitization–Oxidation” strategy, taking use of biomass matter of degreasing cotton as carbon precursor and solution reservoir. With the assistance of the catalytic graphitization effect of iron core, onion-like graphitic carbon (GC) shell is made directly from the biomass at low temperature (650 °C). The nanosized α-Fe 2 O 3 particles would effectively mitigate volumetric strain and shorten Li + transport path during charge/discharge process. The graphitic carbon shells may promote charge transfer and protect active particles from directly exposing to electrolyte to maintain interfacial stability. As a result, the as-prepared α-Fe 2 O 3 @GC composite displays an outstanding cycle performance with a reversible capacity of 1070 mA h g −1 after 430 cycles at 0.2C, as well as a good rate capability of ∼ 950 mA h g −1 after 100 cycles at 1C and ∼ 850 mA h g −1 even up to 200 cycles at a 2C rate. [ABSTRACT FROM AUTHOR]

Single crystal Ni-rich layered oxide cathode materials enjoy better stability compared to polycrystalline materials, exhibiting good prospects in high energy density lithium-ion batteries. However, the poorer structure stability and rate performance are faced for the future large-scale application of single crystal Ni-rich layered oxide cathode material. The synergistic effect of Al and Ti is studied by in-situ differential electrochemical mass spectrometry (DEMS) and in-situ X-ray diffraction (XRD) combination with density functional theory (DFT) calculations to reveal the phase stabilization mechanism, improving the cycling stability of high voltage Ni-rich single crystal Li(Ni 0 · 83 Co 0 · 12 Mn 0.05)O 2 cathode material. It is indicated that bonding energy between the transition metal and oxygen atoms in the layered oxide are increased by introduction of Al and Ti elements, enhancing the stability of lattice oxygen and increasing the diffusion rate of Li+. The Al3+ can inhibit cation mixing, while Ti4+ can optimize the layered structure, which reduces structural failure caused by reaction heterogeneity, enhancing the cycling and rate performance of the cathode material in 4.5 V high voltage. The outstanding stably 500 cycles are obtained with capacity retention rate of 71.8%, compared to the unmodified sample with only 35.1% capacity. [Display omitted] • The Al and Ti were chosen co- modification creatively single crystal Li(Ni 0·83 Co 0·12 Mn 0.05)O 2 (AT-SNCM) composite samples. • AT-SNCM shows greater advantages in terms of rate performance and cycling performance. • The Li + diffusion coefficient analysis, in situ XRD and in situ DEMS tests, and theoretical calculations. • The work provides an effective strategy for the improvement of Ni-rich single cathode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel composite electrolyte was facilely prepared by in-situ polymerization. • The electrolyte showed high ionic conductivity and enhanced mechanical property. • Solid-state cells exhibited outstanding electrochemical performance and good safety. Polymer solid-state electrolytes have been extensively studied for their favorable flexibility, ease of processing, and good interfacial contact. However, the low ionic conductivity, narrow electrochemical window and poor mechanical properties restrict their practical application. Here, a novel poly(N,N'-Methylenebisacrylamide) (PMBA)-based composite electrolyte reinforced with high-strength glass fiber (GF) skeleton is fabricated via in-situ polymerization. Due to the high electrolyte uptake of PMBA network and the strong interaction between the amide units and other components in the electrolyte, it displays high ionic conductivity (1.53 mS cm−1) and lithium-ion transference number (0.74) at ambient temperature, respectively. The synergistic effect of the polymer network and GF skeleton endows the electrolyte with excellent mechanical properties (2.05 GPa), thermal stability, and flame-retardant characteristics. Furthermore, the electrolyte exhibits favorable interface compatibility with the anode and cathode. The Li||Li symmetrical cell exhibits excellent Li plating/stripping reversibility for over 1200 h at 0.1 mA cm−2. The LFP||Li exhibit high discharge capacity of 138.5 mAh/g at 1C. Noteworthy, the LFP|DEE@PMBA-GF|Li cell demonstrates outstanding cycling stability with 83.7 % capacity retention after 600 cycles at 1C and 99.89 % average Coulombic efficiency. Additionally, the LFP|DEE@PMBA-GF|graphite pouch cell with high cathode mass loading (∼12 mg cm−2) demonstrates satisfactory safety and electrochemical performance. [ABSTRACT FROM AUTHOR]

A theoretical electrochemical thermal model combined with a thermal resistive network is proposed to investigate thermal behaviours of a battery pack. The combined model is used to study heat generation and heat dissipation as well as their influences on the temperatures of the battery pack with and without a fan under constant current discharge and variable current discharge based on electric vehicle (EV) driving cycles. The comparison results indicate that the proposed model improves the accuracy in the temperature predication of the battery pack by 2.6 times. Furthermore, a large battery pack with four of the investigated battery packs in series is simulated in the presence of different ambient temperatures. The simulation results show that the temperature of the large battery pack at the end of EV driving cycles can reach to 50 °C or 60 °C in high ambient temperatures. Therefore, thermal management system in EVs is required to maintain the battery pack within the safe temperature range. [ABSTRACT FROM AUTHOR]

A novel hierarchical structure carbon/sulfur composite is presented based on carbon fiber matrices, which are synthesized by electrospinning. The fibers are constituted with hollow graphitized carbon spheres formed using catalytic Ni nano-particles as hard templates. Sulfur is loaded to the carbon substrates via thermal vaporization. The structure and composition of the hierarchical carbon fiber/S composite are characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and nitrogen adsorption isotherms. The electrochemical performance is evaluated by cyclic voltammetry and galvanostatic charge–discharge. The results exhibit an initial discharge capacity of 845 mA h g −1 at 0.25 C (420 mA g −1 ), with a retention of 77% after 100 cycles. A discharge capacity of 533 mA h g −1 is still attainable when the rate is up to 1.0 C. The good cycling performance and rate capability are contributed to the uniform dispersion of sulfur, the conductive network of carbon fibers and hollow graphitized carbon spheres. [ABSTRACT FROM AUTHOR]

The electrochemical performance of the sulfurized polyacrylonitrile (SPAN)/Li cell affected by the Li 2 SiO 3 particles that added between cathode and separator in the assembly process is studied. Fast capacity decay happens to the base SPAN/Li cell without Li 2 SiO 3 due to deactivation of sulfur and side reactions etc.. However, the decay is obviously mitigated in the presence of Li 2 SiO 3 . Reversible capacity retention of 79% can be achieved after 100 cycles at 0.5C, while it is less than 10% for its counterpart. XPS and TEM measurements are conducted and the result indicates a positive effect of Li 2 SiO 3 on the inhibition of side reactions, because Li 2 SiO 3 can hold the dissociated sulfur substances and consume PF 5 /HF in the carbonate electrolyte. [ABSTRACT FROM AUTHOR]

LiNi 0.5 Mn 1.5 O 4 electrode modification is achieved in this work through adding inorganic lithium carbonate (Li 2 CO 3 ) into carbonate electrolyte. Superior cyclic stability of the cathode in the range of 5–2 V is attained, a capacity of 0.3698 mAh g −1 is lost per cycle, which is half of the value in the Li 2 CO 3 -free condition. The capacity loss above and below 3.5 V are both alleviated in the presence of Li 2 CO 3 . Its effect on both the electrolyte bulk and the cathode surface is analyzed with SEM, TEM and XPS measurements. The density functional theory (DFT) calculation is carried out to discuss the modification mechanism. It is speculated that Ni 4+ ⋯CO 3 2− coordination may be formed through the interaction between Ni and O, weakening the oxidizability of Ni 4+ on the electrode surface. In addition, Li 2 CO 3 can consume PF 5 in the electrolyte. The interphase film can also maintain thin and steady during the cycling within 5–2 V. [ABSTRACT FROM AUTHOR]

The electrochemical performance of LiNi 0.5 Mn 1.5 O 4 is investigated in a sand-like carbonate electrolyte containing 4 wt.% lithium metasilicate (Li 2 SiO 3 ). The capacity fading rate of the LiNi 0.5 Mn 1.5 O 4 electrode working in the sand-like electrolyte (2-5 V) is reduced to 0.171 mAh g −1 per cycle, quite smaller than the value of 0.613 mAh g −1 per cycle in the electrolyte without Li 2 SiO 3 . The capacity of 159.5 mAh g −1 is delivered at 0.5 C after 118 cycles while it is only 99.4 mAh g −1 for the Li 2 SiO 3 -free counterpart. Cyclic voltammetry, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopic measurements are conducted to explore the modification mechanism. It is found that the anodic stability of the sand-like electrolyte is improved compared to the base electrolyte. The Li 2 SiO 3 precipitates on the electrode surface make contribution to the performance enhancement of the cathode at high potential. [ABSTRACT FROM AUTHOR]

Abstract: Sodium chloride (NaCl), as an attractive electrolyte additive, was added in a low temperature electrolyte to investigate its effect on LiFePO4 electrode. A capacity as high as 115mAhg−1 was delivered at 2 C, which was 20mAhg−1 more than its NaCl free counterpart. Cyclic voltammetry (CV) tests showed that the polarization of electrode reaction decreased. SEM and XPS measurements were conducted and the result illustrated that the film was modified by NaCl to be uniform containing less resistive LiF, so the transport of Li+ through the film was facilitated. Moreover, the conductivity of Li+ through electrolyte was also enhanced in the presence of NaCl. NaCl effectively facilitated lithium ion transport rate to the electrode surface and improved the lithiation/delithiation behavior in the LiFePO4 electrode. [Copyright &y& Elsevier]

Highlights: [•] A novel anode composite of Fe3O4@CMK-3 for lithium ion batteries. [•] Nano-structured Fe3O4 crystals (∼10nm) are extremely uniformly dispersed on ordered mesoporous carbon. [•] The composite electrode exhibits excellent cycle stability and rate performance. [•] Fine Fe3O4 and unique architecture make great contribution to the electrochemical performance. [Copyright &y& Elsevier]

Abstract: The paper reports a novel nano-structured Cu2O/porous carbon (PC) composite and its application as an anode material for lithium ion batteries. The architecture and the electrochemical performance of the as-prepared composite are investigated through structure characterization and galvanostatic charge/discharge test. Cu2O nanoparticles are well-distributed in the pore channels owing to the nanoscale confinement effect apart from the edges of PC matrix. The composite exhibits a high reversible capacity of 884.4 mA h g−1 after 100 cycles, especially an excellent rate capability of 600.8 mA h g−1 when cycled at the current density of 1000 mA g−1. The outstanding lithium storage properties may be attributed to the designed embedment structure of the composite. The nano-sized Cu2O loaded in the PC promotes the reaction of lithiation/delithiation owing to the large contact area and short lithium ion diffusion distance. Additionally, PC with highly-developed porous structure is capable of accommodating large volume expansion of Cu2O and preventing the aggregation of particles upon continuous cycling. [Copyright &y& Elsevier]

The heat generation rate of nickel-metal hydride battery is investigated during charging/discharging in this study. The heat capacity of 8 Ah cylindrical Ni-MH battery is measured using a large-scale calorimeter. An accelerating rate calorimeter is employed to provide an adiabatic environment for the battery. The generation rates of reaction heat, polarization heat, and combination heat are calculated through curve fitting. Results show that there exits a linear relationship between each generation rate of the three heat items and the charging/discharging currents. It is suggested that the ohm internal resistance of the battery needs to be as low as possible for reducing the ohm heat. In addition, it is better to avoid overcharging in the higher rate of 5 C for battery safety. [ABSTRACT FROM AUTHOR]

The effect of the fluoroethylene carbonate (FEC) addition in electrolyte on LiFePO cathode performance was investigated in low-temperature electrolyte LiPF/EC/PC/EMC (0.14/0.18/0.68). Cyclic voltammetry, electrochemical impedance spectroscopy, and charge/discharge tests were conducted in this work. In the presence of FEC, the polarization of LiFePO electrode decreased both at room and low temperatures. Meanwhile, the exchange current density increased. The rate capability of LiFePO electrode was greatly enhanced as well. The morphology of the solid electrolyte interphase (SEI) on LiFePO surface was modified with the addition of FEC as confirmed by scanning electron microscopy measurement. A compact film with small impedance was formed on LiFePO surface compared to the case of FEC-free. The compositions of the film were analyzed by X-ray photoelectron spectroscopic measurement. The contents of LiPOF, LiF, and the carbonate species generated from solvents decomposition were reduced. The modified SEI promoted the migration of lithium ion through the electrode/electrolyte interphase and enhanced the electrochemical performance of the cathode. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the sorting of nickel–metal hydride batteries is investigated based on their charging thermal behavior. A self-organization map (SOM) model affiliated to artificial neural network is constructed to conduct the sorting work. The sorting principle is described in detail to support the model. A batch of batteries is charged in various rates to collect training data closely related to battery thermal behavior. It is indicated that the model can master the regulation of sorting well after training. As a result, the batteries are classified by the SOM model into three categories of high heat generation battery, middle heat generation battery, and low heat generation battery, which corresponds well with the training result. The model thus allows the batteries in the same category to be selected for the consistency in thermal behavior as well as discharge performance. [Copyright &y& Elsevier]

Abstract: The surface adsorption behavior of polyethyleneglycols (PEG), a wide-used additive in damascene copper plating, was investigated in acidic Cu2+-free electrolyte in the presence of PEG and Cl− by in situ surface enhanced Raman spectroscopy (SERS) and atomic force microscopy (AFM) under potentiostatic conditions. Both SERS and AFM studies indicate that the adsorption amount of PEG gradually increases within ∼30min immersion time at all the examined potentials prior to reaching steady status. It is demonstrated that, at relatively negative potentials in the examined range (−0.15V to −0.35V(SCE)), more PEG are adsorbed on the surface and form less-compact clusters in piles. In situ AFM images show that, in the damascene plating electrolyte containing PEG, Cl− and large amount of H2SO4, the adsorbed PEG appear to be flat-cone shaped clusters with a bottom diameter of several tens of nanometers, and a height of several nanometers. The diameters of the adsorbed clusters increase with time and the cathodic polarization, while the heights of the adsorbed clusters do not increase obviously. The present results suggest that PEG mainly contribute to the slow deposition rate at the external surface of nanometer-sized vias and trenches, for the dimensions of adsorbed PEG clusters are too big to move into the tiny structures. [Copyright &y& Elsevier]

Abstract: Mesoporous activated carbons with high surface area have been prepared from PVDC by NaOH activation for non-aqueous electric double layer capacitors (EDLCs). The BET surface area and pore volume of the carbon reach as high as 2675 m2 g−1 and 1.683 cm3 g−1, respectively. The pore size of the carbon distributes mainly in small mesopore of 2∼4 nm, which is ideal for non-aqueous electrolyte EDLCs. The unique microstructure features, i.e. very high surface area and optimized pore size make the carbon present both a high capacitance of 155 F/g and outstanding rate capability in non-aqueous electrolytes. As the current density increases to 18 000 mA/g, it remains 109 F/g, an attractive value for EDLCs. [Copyright &y& Elsevier]

The effect of surface modification of amorphous MgNi by carbon or Ni was examined by conventional charge/discharge cycle tests and by a newly developed micro-paste electrode method. The change/discharge tests showed that the surface modification by Ni had no effect on the capacity degradation of amorphous MgNi. The carbon modification, however, clearly improved the degradation; the discharge capacity after six cycles was still ∼220 mA/g, which was about twice that of the unmodified sample. In cyclic voltammograms (CVs) obtained for the carbon-modified samples using the micro-paste electrode technique, the potential at the rising of the cathodic current shifted to the anodic direction and the anodic peak was sharper and larger than those for the unmodified sample. In addition, the CVs observed for carbon-modified samples immersed in 6 N KOH solution, which can be regarded as degraded samples, revealed that the deposited carbon suppressed the reduction in the electron transfer rate due to Mg(OH)2 formation. Potential step measurements for the carbon-modified samples, on the other hand, showed that carbon modification on MgNi did not affect the diffusion process of hydrogen. [Copyright &y& Elsevier]

Choosing suitable solvent is the key technology for the electrochemical performance of energy storage device. Among them, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and ethylene sulfite (ES) are the potential organic electrolyte solvents for lithium/sodium battery. However, the quantitative relation and the specific mechanism of these solvents are currently unclear. In this work, density functional theory (DFT) method is employed to study the lithium/sodium ion solvation in solvents of VC, ES, and FEC. We first find that 4VC-Li+, 4VC-Na+, 4ES-Li+, 4ES-Na+, 4FEC-Li+, and 4FEC-Na+ are the maximum thermodynamic stable solvation complexes. Besides, it is indicated that the innermost solvation shells are consisted of 5VC-Li+/Na+, 5ES-Li+/Na+, and 5FEC-Li+/Na+. It is also indicated that the Li+ solvation complexes are more stable than Na+ complexes. Moreover, infrared and Raman spectrum analysis indicates that the stretching vibration of O = C peak evidently shifts to high frequency with the Li+/Na+ concentration reducing in nVC-Li+/Na+ and nFEC-Li+/Na+ solvation complexes, and the O = C vibration peak frequency in Na+ solvation complexes is higher than that of Li+ complexes. The S = O stretching vibration in nES-Li+/Na+ solvation complexes moves to high frequency with the decrease of the Li+/Na+ concentration, the S = O vibration in nES-Na+ is higher than that in nES-Li+. The study is meaningful for the design of new-type Li/Na battery electrolytes. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: We successfully prepared the Li‐VO2(M) nanosheets via a facile lithiation method. After compositing with conductive carbon fibers, the sulfur host (Li‐VO2(M)@CFs) combines the efficient adsorption ability of the VO2(M) with superior electronic conductivity of the carbon fibers. Besides, carbon fiber cloth used as the current collector can provide the 3D electronic channels. Therefore, the coin cells exhibited the superior reversible capacity of 1250 mA h g–1 at 0.2 C and a low capacity decay value of 0.068% per cycle within 416 cycles at 1 C, indicative of the favorable cycling stability. Moreover, even at a high rate of 5 C, it also kept at a high discharge capacity of 401 mA h g–1. In conclusion, this work discloses an attractive route to reduce the dissolution loss of lithium polysulfides (LiPSs) and enhance the overall performance of Li‐S batteries. [ABSTRACT FROM AUTHOR]

The electrolytes in lithium metal batteries have to be compatible with both lithium metal anodes and high voltage cathodes, and can be regulated by manipulating the solvation structure. Herein, to enhance the electrolyte stability, lithium nitrate (LiNO3) and 1,1,2,2‐tetrafuoroethyl‐2′,2′,2′‐trifuoroethyl(HFE) are introduced into the high‐concentration sulfolane electrolyte to suppress Li dendrite growth and achieve a high Coulombic efficiency of >99 % for both the Li anode and LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes. Molecular dynamics simulations show that NO3− participates in the solvation sheath of lithium ions enabling more bis(trifluoromethanesulfonyl)imide anion (TFSI−) to coordinate with Li+ ions. Therefore, a robust LiNxOy−LiF‐rich solid electrolyte interface (SEI) is formed on the Li surface, suppressing Li dendrite growth. The LiNO3‐containing sulfolane electrolyte can also support the highly aggressive LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode, delivering a discharge capacity of 190.4 mAh g−1 at 0.5 C for 200 cycles with a capacity retention rate of 99.5 %. [ABSTRACT FROM AUTHOR]

The electrolytes in lithium metal batteries have to be compatible with both lithium metal anodes and high voltage cathodes, and can be regulated by manipulating the solvation structure. Herein, to enhance the electrolyte stability, lithium nitrate (LiNO3) and 1,1,2,2‐tetrafuoroethyl‐2′,2′,2′‐trifuoroethyl(HFE) are introduced into the high‐concentration sulfolane electrolyte to suppress Li dendrite growth and achieve a high Coulombic efficiency of >99 % for both the Li anode and LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes. Molecular dynamics simulations show that NO3− participates in the solvation sheath of lithium ions enabling more bis(trifluoromethanesulfonyl)imide anion (TFSI−) to coordinate with Li+ ions. Therefore, a robust LiNxOy−LiF‐rich solid electrolyte interface (SEI) is formed on the Li surface, suppressing Li dendrite growth. The LiNO3‐containing sulfolane electrolyte can also support the highly aggressive LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode, delivering a discharge capacity of 190.4 mAh g−1 at 0.5 C for 200 cycles with a capacity retention rate of 99.5 %. [ABSTRACT FROM AUTHOR]

The high valence and large ionic radius of Mo6+ is selected as a dopant to modify the LiNi 0.6 Co 0.2 Mn 0.2 O 2 material through the molecular level mixed calcination method. The Mo6+ substitutes the transition metal atoms in the material proportionately, which has no influence on the original atom ratio of the transition metal, and may expand the Li+ diffusion pathways. The strong bond energy of Mo-O benefits the stability of the material. Meanwhile the electrochemical reaction of Mo6+/Mo4+ in the process of charging and discharging might increase the capacity of the material. The electrochemical impedance spectroscopy clearly demonstrates that the Mo-doping reduces the charge transfer impedance and enhances the electrochemical reaction activity of the lithium ion. When x = 0.01, the material shows an excellent cycling and rate performance. The discharge specific capacity can reach up to 208 mAh g−1 at 0.2C under 2.8 V–4.6 V, and remains 75% of the first discharge capacity after 101 cycles, which is 10% higher than the un-doped material. • Mo doping cathode exhibits fine structure and electrochemical performance in doping amount of x = 0.01. • Mo doping reduces the cation mixing and broadens the lithium ion migration channel. • Stronger Mo O bond may suppress precipitation of lattice oxygen and stabilize the surface of the material. [ABSTRACT FROM AUTHOR]

The hard carbon (HC) is the key anode materials for sodium ion batteries. While the electrolyte and interface from carbonate-based and ether-based electrolytes on the HC has not been deeply analysed. Herein, by combining the theory calculation with experiments analysis of Fourier transform infrared spectroscopy, we successfully construct accurate Na+-solvents models that the oxidation resistance stability of Na+[EC 2 /EMC/DMC][PF 6 −] complexes are better than that of Na+[DIGLYME 4 ][CF 3 SO 3 −] sheaths. And also, the reduction resistance stability of the ether-based electrolyte is better than that of ester-based electrolyte. It is also demonstrated that the ether-based electrolytes generate dense, thin and fast Na-ions transport SEI on the HC particles at the initial stage of the electrochemical cycle, and the organics fill the gaps between inorganics in carbonated ester-based electrolytes, effectively preventing electrolyte decomposition and permeation in the long cycling process by CV, TEM, EIS, AFM, ToF-SIMS and XPS analysis. It is also found that the ratio of organic to inorganic components in DIGLYME-based electrolyte is greater than in EC/DMC/EMC-based electrolyte after cycling, which may affect the electrochemical performance of cells. [ABSTRACT FROM AUTHOR]

Abstract The effect of different current density on the structure transformation of LiNi 0.6 Co 0.2 Mn 0.2 O 2 material is studied under a cut-off voltage (4.6 V). It shows that the capacity fading is accelerated at the high discharge current density. It is mainly caused by the structure instability of the material. When the current density increases, the loss of lithium on the surface of the material becomes severe, and the oxidation state becomes higher. The unit cell parameters also change, parameter a becomes larger, while the c becomes smaller. At the same time, the high discharge current density has a catalytic effect on the structural transformation, and in terms of high charging voltage, the surface structure changes to a rock salt phase. The cathode material is covered by a 3-nm-thick and discontinuous rock salt phase after cycling 50 times at the current density of 100 mA g−1. However, when the material is cycled at the current density of 1000 mA g−1, the rock salt phase becomes thicker (5∼7-nm-thick) and more continuous, which leads to a fast capacity fading. [ABSTRACT FROM AUTHOR]

• Deeply understand the failure factors of Ni-rich low-Co cathode materials. • Theoretical calculation and advanced in-situ characterization of study failure mechanism. • Understand the corresponding relationship between methods and failure at different levels. • Summarize the targeted and effective modification mechanism of Ni-rich cathode materials. LiNi 1−x−y Co x Mn y O 2 /LiNi 1−x−y Co x Al y O 2 (NCM/NCA) materials, the high energy density (>300 Wh kg−1) transition metal layered oxide cathode, especially Ni-rich and low-Co materials are promoting the development of electric vehicles, while the poorer electrochemical cycling performance and safety that need to be addressed before dominant in commercialization. Understanding and targeting the bulk phase and interface mechanisms of Ni-rich NCM/NCA materials is the most effective means of solving the failures due to the migration of transition metal ions, the irreversible evolution of the structure within the bulk phase, the cracking and side reactions of particles at the interface of the cathode material. An in-depth explanation of the internal lattice distortion, lithium-nickel mixing, microcracking and oxygen generation mechanisms of high energy density layered oxide cathodes and some targeted component and structure design, interface modification methods are summarized by demonstrating the reaction and evolution mechanisms of NCM/NCA materials, as well as the theoretical calculation and means of in-situ advanced characterization of these deterioration mechanisms. This helps to accelerate the large-scale application and domination of high energy density Ni-rich and low-Co NCM/NCA materials in electric vehicles. [ABSTRACT FROM AUTHOR]

[Display omitted] • The electrochemical performance of Single-crystalline nickel-rich cathodes were improved by a novel strategy of strengthening Li+/Ni2+ cation mixing effect. • The mechanism is well revealed by the density functional theory calculations combined with in-situ experimental analysis. • The relationship between Li+/Ni2+ cation mixing and electrochemical performance is established, further recognizing the dual characteristics of cation mixing. Single-crystalline nickel-rich layered NCM are promising candidate materials for advanced Li-ion batteries in long-range electric vehicles. However, several shortcomings must be overcome before full commercial utilization, including the lower specific capacity and poorer rate performance than polycrystalline layered cathodes, especially in the deep delithiation state. Herein, the Li+/Ni2+ cation mixing effect is strengthened by executing Nb-substitution to improve electrostatic interactions and electrochemical performances. Density functional theory calculation combined with in-situ experimental analysis are used to reveal the mechanism of Nb-substitution in regulating Li+/Ni2+ cation mixing effect. Stabilizing layered structure is intrinsically implemented through the regulation of Ni2+/Ni3+ ions. The Nb substitution is also found beneficial in enhancing the structural stability owing to the high bond energy of Nb-O. The optimal single-crystalline LiNi 0.79 Nb 0.01 Co 0.1 Mn 0.1 O 2 exhibits better electrochemical performances in terms of high discharge capacity (209.9 mAh g−1) and high rate durability (91.4% retention after 100 cycles under 5 C). In sum, the proposed strategy looks promising for the design of high-performance cathodes, as well as the optimization of single-crystalline cathodes, promoting the application in high-energy–density batteries. [ABSTRACT FROM AUTHOR]

High ionic conductivity and good interface compatibility have always been two major bottlenecks for solid-state electrolytes. Herein, a composite electrolyte membrane comprising poly (propylene carbonate), PVDF-HFP and Li 6 · 3 La 3 Zr 1 · 4 Ta 0 · 6 O 12 is successfully prepared via electrospinning. With the assistance of succinonitrile, the synthesized solid-state electrolyte exhibits high ionic conductivity (1.32 × 10−3 S cm−1 at room temperature), oxidation potential up to 4.5 V vs Li/Li+ and high Li+ transference number (0.81). This desirable performance is attributed to the combination of PPC with good Li+ conduction ability and PVDF-HFP with excellent mechanical properties, forming a continuous transport framework within the electrolyte. The introduced active fillers and small molecular additive not only benefit to fast Li+ mobility, but also reinforce the stability towards Li metal. Li symmetric cell using the solid-state electrolyte can last for 800 h at a current density of 1.0 mA cm−2 with a low overpotential. The NCM811 cell using the electrolyte membrane shows high initial discharge specific capacity (184.3 mAh g−1 at 1 C) and good capacity retention (80.1% after 300 cycles at 30 °C). [Display omitted] • A self-supporting membrane with conducting fibrous network was designed. • The electrolyte displayed high ionic conductivity and good mechanical property. • The cell with the electrolyte exhibited outstanding electrochemical performance. [ABSTRACT FROM AUTHOR]