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The reaction mechanism and kinetics of synthesis Li1.16(Ni0.25Mn0.75)0.84O2 were studied at different heating rates with the thermal analysis (TG-DTA) and non-isothermal kinetic analysis. The average activation energies were 167.40 kJ·mol−1 and 139.69 kJ·mol−1 between 200 and 450 °C (peak 2), and 450 and 560 °C (peak 3) as calculated by the Flynn-Wall-Ozawa and Kissinger methods. The reaction order, frequency factor, and kinetic equation of peak 2 and peak 3 were determined by the Kissinger method. Based on the results of the mechanism and dynamic study, the Li-rich and Mn-based cathode materials Li1.16(Ni0.25Mn0.75)0.84O2 were synthesized by an optimized two-step sintering process. The study results show that the materials show a layer structure with high crystallinity and superior electrochemical performance. Notably, the sample exhibits the discharge capacity of 225.4 mAhg−1, 92.7% of the initial discharge capacity after 300 cycles, accompanying with a high energy density retention of 140 Whkg−1.

Due to the theoretical ultrahigh energy density of the Li-O2 battery chemistry, it has been hailed as the ultimate battery technology. Yet, practical Li-O2 batteries usually need to be designed in a large-sized pattern to actualize a high specific energy density, and such batteries often cannot be cycled effectively. To understand the inherent reasons, we specially prepared large-sized (13 cm × 13 cm) Li-O2 model batteries with practical energy output (6.9 Ah and 667.4 Wh/kgcell) for investigations. By subregional and postmortem analysis, the cathode interface was found to have severe local inhomogeneity after discharge, which was highly associated with the electrolyte and O2 maldistribution. The quantitative results by X-ray photoelectron spectroscopy (XPS) evidenced that this local inhomogeneity can exacerbate the generation of lithium acetate during charge, where the locally higher ratio of unutilized carbon surface and less Li2O2 after discharge would result in increased lithium acetate formation for a subsequent local overcharge. Moreover, verification experiments proved that the byproduct lithium acetate, which had been of less concern, was recalcitrant and triggered much larger polarization compared with the commonly reported byproduct Li2CO3 during battery operations, further revealing the key limiting factors leading to the poor rechargeability of batteries by its accumulation at a pouch-type cell level.

Cathode interface instability is a significant obstacle for the practical application of sulfide-based all-solid-state lithium-ion batteries (ASSLIBs). However, the origin of cathode interface degradation is lack of comprehensive understanding. In this paper, X-ray characterizations combined with electrochemical analysis are adopted to investigate the underlying degradation mechanism at cathode interface. The results indicate that residual lithium compounds on the surface of Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) are the main reason that triggering the oxidation of sulfide solid-state electrolytes (SSEs), therefore inducing severe side-reactions at cathode interface and structural degradation of NMC811. The degradation of the cathode interface can be significantly suppressed when the cathode surface is cleaned. As a result, the surface cleaned NMC811 without coating demonstrates significantly improved electrochemical performance in both Li5.5PS4.5Cl1.5 (LPSCl) and Li10GeP2S12 (LGPS) based ASSLIBs, proving the universal application of this strategy.

The development of high-performance sulfide electrolyte-based all-solid-state lithium-ion batteries (ASSLIBs) has been inhibited by problematic ionic transport and side reactions at the cathode interface, and their success is dependent on the functionalized interface upon charging and discharging. Despite recent progresses, it has proven challenging to design a favorable interface that can suppress the side reactions and enable smooth motion of Li+ ions. Herein, a favorable Zr-based cathode interface is elaborately manipulated by the atomic layer deposition (ALD) for sulfide-based ASSLIBs. Flexile control over the Li sub-cycle during the preparation process is demonstrated to be crucial for achieving a robust cathode interface with a desirable Li+ ionic conductivity. The ASSLIBs equipped with this functional interface exhibit excellent cycling stability and rate capability at room temperature (RT). Various electrochemical and spectroscopic characterizations reveal that the ionic conductive interface can significantly limit side reactions and induce a low polarization of the (de)intercalation toward cathode materials. The interfacial manipulation regarding ionic conductivity and structure realized by ALD provides a new strategy to achieve high-performance ASSLIBs.

Li–O2 battery is a promising rechargeable battery candidate due to its ultrahigh theoretical energy density. However, safety issues and poor cycling stability of Li–O2 batteries caused by the forma...

The separator is used to isolate the cathode and anode material, playing an important role in the safety of battery, which prevents internal short circuit of battery and provides lithium ions free flow channels. In this paper, based on the commercial ceramic-coated polyethylene (PE) separator (CPES), low-melting point PE microspheres were mixed in ceramic-coating to form the functionalized PE separator (FPES) for improving the safety tolerance of large scale lithium-ion batteries (LIBs). Compared to the CPES shutdown temperature of ~135 °C, the shutdown temperature of FPES significantly decreased to ~110 °C. Compared with 27 Ah pouch battery assembled by CPES, the FPES can effectively improve the tolerance of overcharge and internal short circuit without sacrificing the electrochemical performance. In addition, a novel internal short circuit of FPES protection mechanism model was proposed. Molten PE microspheres of FPES would flow along the edge of broken hole, reducing the contact probability between the cathode and anode, and ultimately increasing the resistance of internal short circuit by 41% compared to CPES. Therefore, the obtained results provide important implications for the development of safer separator and LIBs.

All-solid-state lithium-ion batteries (ASSLIBs) are receiving significant attention owing to their improved safety and energy density over liquid counterparts. However, single-crystal cathodes have never been investigated in ASSLIBs. In this work, single-crystal Li(Ni0·5Mn0·3Co0.2)O2 (SC-NMC532) is used as the cathode material for ASSLIBs, which exhibits 6–14 times higher Li+ diffusion coefficient than polycrystalline Li(Ni0·5Mn0·3Co0.2)O2 (PC-NMC532). As a result, SC-NMC532 exhibits an initial specific capacity of 156.4 ​mAh.g−1 while PC-NMC532 shows an initial capacity of only 127.5 ​mAh.g−1. After 150 cycles, SC-NMC532 retains the capacity of 94.5 ​mAh.g−1. More impressively, under a high current density of 1.3 ​mA ​cm−2, SC-NMC532 exhibits a capacity of 82 ​mAh.g−1, much higher than that of PC-NMC532 (2.1 ​mAh.g−1). This work demonstrates that single-crystal NMC cathodes could enable both high power density and high energy density of ASSLIBs.

Li–O2 batteries have attracted significant interest in the past decade owing to their superior high specific energy density in contrast to conventional lithium ion batteries. An 8.7-Ah Li–O2 pouch cell with 768.5 Wh kg−1 was fabricated and characterized in this investigation and the factors that influenced the electrochemical performance of the Li–O2 pouch cell were studied. In contrast to coin/Swagelok-type Li–O2 cells, it was demonstrated that the high-loading air electrode, pulverization of the Li anode, and the large-scale inhomogeneity of the large pouch cell are the major reasons for the failure of Li–O2 batteries with Ah capacities. In addition, safety tests of large Li–O2 pouch cells were conducted for the first time, including nail penetration, crushing, and thermal stability. It was indicated that a self-limiting mechanism is a key safety feature of these batteries, even when shorted. In this study, Li–O2 batteries were investigated in a new size and capacity-scale, which may provide useful insight into the development of practical pouch-type Li–O2 batteries.

All-solid-state lithium sulfur batteries (ASSLSBs) are considered promising candidates for next-generation energy-storage systems due to their enhanced safety and high theoretical energy density. However, usually both solid-state electrolyte (SSE) and conductive carbon need to be incorporated into the cathode composite to provide Li+/electron pathways, leading to the reduced energy density and inevitable SSE decomposition. Moreover, the real electrochemical behavior of S or Li2S cathodes can not be reflected due to the partially overlapped redox reaction of SSE. Herein, a series of unique P4S10+n cathodes for high-performance ASSLSBs that totally do not need any extra SSE additives are reported. Synchrotron-based X-ray absorption near edge structure coupled with other analyses confirmed that ionic conductive Li3PS4 together with Li4P2S6 components can be electrochemically self-generated during lithiation process and partially maintained to provide fast Li+ transport pathways within the cathode layer. This is further evidenced by a 30–43-fold higher reversible capacity for P4S10+n/C cathodes compared to a S/C cathode. Bulk-type ASSLSBs based on the P4S34/C cathode show a highly reversible capacity of 883 ​mAh g−1 and stable cycling performance over 180 cycles with a high active material content of 70 ​wt%. The present study provides a promising approach for generating ionic conductive components from the electrode itself to facilitate Li+ migration within electrodes in ASSLSBs.

All-solid-state lithium-ion batteries (ASSLIBs) are expected as safe and high-performance alternatives to replace the conventional liquid-based lithium-ion batteries. However, the incompatible interface between the most cathode materials and sulfide-based solid electrolytes is still challenging the stable delivery of electrochemical performance for ASSLIBs. Herein, a dual-functional Li3PO4 (LPO) modification is designed for Ni-rich layered oxide cathodes in sulfide-based ASSLIBs to realize the high performance. The modified cathode demonstrates a significantly improved initial capacity of 170.6 ​mAh g-1 at 0.1C, better rate capability, and reduced polarization compared to the bare cathode. More importantly, a stable long-term cycling is achieved with a low capacity degradation rate of 0.22 ​mAh g-1 per cycle for 300 cycles at 0.2C. The detailed surface chemical and structural evolutions are studied via X-ray absorption near edge spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The results indicate that the LPO modification not only significantly suppresses the side-reactions with sulfide electrolyte but also helps to alleviate the deterioration of the microstructural cracks during the electrochemical reactions. This work provides an ideal and controllable interfacial design for realizing high performance sulfide-based ASSLIBs, which is readily applicable to other solid-state battery systems.

The enabling of high energy density of all-solid-state lithium batteries (ASSLBs) requires the development of highly Li+-conductive solid-state electrolytes (SSEs) with good chemical and electrochemical stability. Recently, halide SSEs based on different material design principles have opened new opportunities for ASSLBs. Here, we discovered a series of LixScCl3+x SSEs (x = 2.5, 3, 3.5, and 4) based on the cubic close-packed anion sublattice with room-temperature ionic conductivities up to 3 × 10-3 S cm-1. Owing to the low eutectic temperature between LiCl and ScCl3, LixScCl3+x SSEs can be synthesized by a simple co-melting strategy. Preferred orientation is observed for all the samples. The influence of the value of x in LixScCl3+x on the structure and Li+ diffusivity were systematically explored. With increasing x value, higher Li+, lower vacancy concentration, and less blocking effects from Sc ions are achieved, enabling the ability to tune the Li+ migration. The electrochemical performance shows that Li3ScCl6 possesses a wide electrochemical window of 0.9-4.3 V vs Li+/Li, stable electrochemical plating/stripping of Li for over 2500 h, as well as good compatibility with LiCoO2. LiCoO2/Li3ScCl6/In ASSLB exhibits a reversible capacity of 104.5 mAh g-1 with good cycle life retention for 160 cycles. The observed changes in the ionic conductivity and tuning of the site occupations provide an additional approach toward the design of better SSEs.

Sulfide-based solid-state electrolytes (SSEs) are considered a key part in the realization of high-performance all solid-state lithium-ion batteries (ASSLIBs). However, the incompatibility between ...

Sulfide solid electrolytes have recently attracted significant interest for use in all-solid-state lithium batteries (ASSLBs) due to their high ionic conductivity. However, one of the main challeng...

A Li-rich layered oxide material of Li1.18Mn0.52Co0.15Ni0.15O2 with Li3PO4 as an outer modification layer and a spinel as an inner modification layer on the surface of primary particles was synthesized by a facile synchronous method. A series of physical characterization techniques indicate that Li3PO4 and the spinel simultaneously form not only on the surface but also in the bulk of the cathode material during the preparation process. Consequently, a stable protective layer and a highly conductive interlayer are fabricated by the formation of the Li3PO4 and spinel phase on the primary particle surface of the cathode material. The modified sample exhibits an improved initial coulombic efficiency of approximately 88.5%. Moreover, the capacity retention of the modified sample increases to 92% after 100 cycles at a rate of 0.2C from 2.0 to 4.8 V compared to that of the pristine sample (62.7%). Moreover, the modified sample also exhibits an excellent rate capability of 171.4 mA h g−1 at a 5C rate relative to the pristine sample (134.1 mA h g−1). Our facile modification approach combines the merits of the spinel phase and the Li3PO4 compound. Also, our approach can remarkably suppress the structural transformation from layered to spinel-like and decrease the loss of active materials by mitigating the formation of corrosion pits on the particles as well as enhancing the dynamic performance of Li+ diffusion of Li-rich layered oxides.

Due to higher energy density, high-voltage all-solid-state lithium batteries (ASSLBs) have attracted increasing attention. However, they require solid-state electrolytes (SSEs) with wide electrochemical stability windows (ESW, typically >4.2 V) and high-stability against the Li anode. Nevertheless, poly(ethylene oxide) (PEO), the most widely used solid polymer electrolyte (SPE), can’t tolerate a high-voltage over 4 V. Whether the main chain (–C–O–C–) or the terminal hydroxide group (–OH) is the limiting factor for the narrow ESW remains unknown. Herein, poly(ethylene glycol) (PEG) and poly(ethylene glycol)dimethyl ether (PEGDME) with different terminal groups are selected to answer this question. The results show that the reactive terminal –OH group is the limiting factor towards applicability against high voltage and the Li anode. Replacing –OH with more stable –OCH3 can significantly extend the ESW from 4.05 to 4.3 V, while improving the Li-anode compatibility as well (Li–Li symmetric cells stably run for 2500 h at 0.2 mA cm−2). Its practical application is further proved by developing PEGDME-based ASSLB pouch cells. The 0.53 mA cm−2 Li–LiFePO4 and 0.47 mA h cm−2 Li–LiNi0.5Mn0.3Co0.2O2 cells demonstrated high capacity retention of 97% and 90% after 210 cycles and 110 cycles, respectively. This work offers a new strategy for PEO-based high-voltage ASSLB development by changing the unstable terminal groups.

A practical strategy to enhance the electrochemical performance of Li-rich and Mn-based Li1.38Ni0.25Mn0.75O2.38 has been introduced. Its micromorphology and microstructure are controlled during the preparation process. Powder X-ray diffraction (XRD) and Raman spectroscopy reveal that the as-obtained materials can be indexed as the α-NaFeO2 phase. Field emission scanning electron microscopy (FESEM) analyses demonstrate that the as-fabricated Li1.38Ni0.25Mn0.75O2.38 materials consist of 10–15 μm spherical secondary particles aggregating with spherical nanoscale primary particles, and the primary particle size and stacking faults can be controlled by altering the calcination temperature. The electrochemical measurements show that Li1.38Ni0.25Mn0.75O2.38 with nanoscale primary particles with the diameter of 100–200 nm and an appropriate amount of stacking faults obtained at 850 °C exhibits higher capacity and superior cycling performance, delivering an initial discharge capacity of 265.7 mA h g−1 at 0.1C, 243.1 mA h g−1 at 0.2C, 222 mA h g−1 at 1.0C and 169 mA h g−1 at 2.0C, accompanied with a capacity retention of 89.3% and 78.6% after 300 cycles and 500 cycles at 1.0C, respectively. Meanwhile, the XPS, EIS and TEM results of the electrodes indicate that the capacity fading in the first 50 cycles may be caused by interfacial side-reactions between electrode and electrolyte.

Silicon nanowires of high purity and regular morphology are of prime importance to ensure high specific capacities of lithium-ion batteries and reproducible electrode assembly process. Using nickel formate as a metal catalyst precursor, straight silicon nanowires (65–150 nm in diameter) were directly prepared by electrolysis from the Ni/SiO2 porous pellets with 0.8 wt% nickel content in molten CaCl2 at 900 °C. Benefiting from their straight appearance and high purity, the silicon nanowires therefore offered an initial coulombic efficiency of 90.53% and specific capacity of 3377 mAh/g. In addition, the silicon nanowire/carbon composite exhibited excellent cycle performance, retaining 90.38% of the initial capacity after 100 cycles. Whilst further study on the charge storage performance is still ongoing, these preliminary results demonstrate that nickel formate is an efficient and effective metal catalyst precursor for catalytic preparation of high purity straight silicon nanowires via the molten salt electrolysis, which is suitable for large-scale production.

Poly(ethylene oxide) (PEO) based solid polymer electrolytes (SPEs) have been regarded as promising electrolytes for next-generation all-solid-state lithium batteries (ASSLBs). However, they have achieved limited cycling stability due to their inability to suppress Li dendrite growth. Herein, a self-healing electrostatic shield (SHES) is proposed to force uniform lithium deposition by introducing 0.05 M Cs+. At this situation, the Cs+ shows a lower reduction potential compared to the Li+ reduction potential (1.7 M). During lithium deposition, the Cs+ forms a positively charged electrostatic shield around the initial Li tips, which forces further deposition of lithium to adjacent regions of the anode and results in a dendrite-free Li deposition. With this in mind, the Li–Li symmetric cells can operate for 1000 and 500 h at current densities of 0.1 and 0.2 mA cm−2, respectively, which are 10 times longer than Cs+-free PEO electrolyte. Moreover, the Li/PEO-Cs+/LiFePO4 (LFP) cell achieves high capacity retention of 90% within 100 cycles at 0.5C and retains a high capacity of 113 mAh g−1 at 0.8C, while short-circuits are observed for the Li/PEO/LFP cell, even at 0.2C. This strategy will generate substantial interest and shed light on the development of other dendrite-free SPEs and ASSLBs systems.

All-solid-state lithium-ion batteries (SSLIBs) are promising candidates to meet the requirement of electric vehicles due to the intrinsic safety characteristics and high theoretical energy density....

All-solid-state lithium batteries (ASSLBs) assembled with solid polymer electrolytes (SPEs) have been regarded as promising next-generation rechargeable batteries with improved safety and high energy densities. However, the Li dendrites and poor Li+ transport greatly inhibit their practical applications when coupled with relatively high loading cathodes. Herein, we combine a glass fiber (GF)-reinforced composite polymer electrolyte based on poly(ethylene oxide) (labeled as PEO@GF) to suppress Li dendrite growth with a freeze-casted vertically-aligned (VL) electrode to facilitate Li+ transport in the high loading cathode. Benefiting from the enhanced mechanical strength and uniformed Li deposition enabled by the implanted GF, the Li–Li symmetric cells exhibit significantly improved cycling stability up to 2000 h (0.2 mA cm−2, 0.2 mAh cm-2) and 1000 h (0.42 mA cm−2, 0.4 mAh cm−2), which are over one order of magnitude longer than those of the pure PEO electrolyte. Furthermore, VL-LiFePO4 (LFP) cathode divides the thick electrode into numerous vertically-aligned “thin electrodes”, which significantly decreases the Li+ transport distance and enables the Li | PEO@GF | VL-LFP cell with a high LFP loading of 10.5 mg cm-2 to deliver a high areal capacity of 1.52 mAh cm−2. The rational structure design of both electrolyte and electrode offers an opportunity for developing high-performance ASSLBs with high active material loadings.

Safe, high-energy-density and long-life Li metal batteries (LMBs) are highly attractive as a power source. However, the development of LMBs encounters serious challenges due to the formation of Li dendrites and the leakage and flammability of organic liquid electrolytes. Herein, a novel nanowire-film-reinforced hybrid gel polymer electrolyte (HGPE) is developed. The interconnected porous nanowire film as the backbone not only strengthens the mechanical structure of GPEs but also ensures the continuity for Li+ conduction. The designed HGPE can simultaneously achieve the suppression of Li dendrites and high ionic conductivity (1.04 × 10−3 S cm−1). The films with controllable thicknesses offer the ability to prepare ultrathin HGPEs with great mechanical properties. With these merits, the Li metal symmetric cells exhibit significantly enhanced cycling stability for over 2100 h with low overpotential. The Li–O2 battery using the HGPE also delivers an ultralong cycle life of up to 494 cycles. The present study may open a new window for reinforcing GPEs and offer an opportunity for developing quasi-solid-state LMBs.

Li- and Mn-rich (LMR) layered materials with large specific capacities are one of the most promising cathodes for high-energy Li-ion batteries. However, the oxygen redox reaction induced by the activation of the Li2MnO3 component leads to lattice oxygen release and transition metal migration from the surface, which result in a large irreversible capacity loss, poor rate capability and inferior cycle stability compared with other cathodes. In this study, an integrated surface modification of combining a coating and chemical treatment is proposed to achieve modified LMR cathode materials with graphene wrapping layers and surface spinel phases. The graphene layer promotes electron transfer, and the spinel phase interlayer accelerates Li+ diffusion. Simultaneously, the combination of the two components increases the structural stability of LMR materials. As a result, the surface-modified LMR cathode exhibits a high rate capability of 154.3 mA h g−1 at 5C and an excellent cycle stability with a capacity retention of 84.2% after 200 cycles at 1C. In addition, the structural evolution of the surface-modified LMR cathode material was studied by in situ synchrotron X-ray diffraction analysis during the charge–discharge process, which illustrates that the surface modification has a significant effect on mitigating oxygen release by enhancing the surface structural stability.

Safe and high-energy-density lithium rechargeable batteries are urgently required for vehicle electrification and grid energy storage. All-solid-state lithium metal batteries (ASSLMBs) are regarded as a good choice to meet these stringent requirements. However, interfacial instability between Li metal and solid-state sulfide electrolytes (SEs) and lithium dendrite formation are main challenges to be overcome. In this work, molecular layer deposition (MLD) is employed for the first time to develop an inorganic-organic hybrid interlayer (alucone) at the interface between the Li metal and SEs. It is found that the alucone layer can serve as an artificial solid electrolyte interphase (SEI). As a result, interfacial reactions between Li and SEs are significantly suppressed by intrinsically blocking electron transfer at the interface. In addition, lithium dendrites are also suppressed. Coupled with a LiCoO2 cathode, ASSLMBs with 30 MLD cycles of alucone on Li metal exhibit a high initial capacity of 120 mAh g−1 and can retain a capacity of 60 mAh g−1 after 150 cycles. This work exemplifies the use of MLD to stabilize the interface between SEs and Li metal for ASSLMBs.

Nickel-rich layered oxide and graphite–SiOx are regarded as promising electrode materials for high energy density lithium ion cells. It is significant to illustrate the degradation mechanism related to the aging process of nickel-rich layered oxide cathode and graphite–SiOx anode in full cell. In this study, the as-prepared pouch cell with LiNi0.88Co0.09Al0.03O2 as cathode material and graphite–SiOx as anode material has been proved with three aging stages according to the capacity retention changes in behavior. The aging process of the pouch cell is studied by non-destructive electrochemical methods. And then the pouch cells at different aging stages are disassembled and the cell components are studied by electrochemical characterizations for reassembled electrodes and physico-chemical analysis techniques. In the result, the cathode degradation is slight and as a minor factor for the degradation of the whole cell, and the anode deterioration is worse and as the main factor for the degradation of the whole cell. The organic and inorganic composition changes of the solid electrolyte interphase (SEI) induce the aging behavior differences of the three stages, and the reversible lithium loss, electrochemical polarization and active material shedding are mainly responsible for the three stages, respectively.

Understanding the relationship between structure, ionic conductivity, and synthesis is the key to the development of solid electrolytes for all-solid-state Lithium batteries. Here, we investigate chloride solid electrolytes with compositions Li3 − 3xM1+xCl6 (-0.14 x ≤ 0.5, M = Tb, Dy, Ho, Y, Er, Tm). When x > 0.04, a trigonal to orthorhombic phase transition occurs in the isostructural Li-Dy-Cl, Li-Ho-Cl, Li-Y-Cl, Li-Er-Cl and Li-Tm-Cl solid electrolytes. The new orthorhombic phase shows a four-fold increase in ionic conductivity up to 1.3×10− 3 S cm− 1 at room temperature for Li2.73Ho1.09Cl6 (x = 0.09) when compared to the trigonal Li3HoCl6. For isostructural Li-Dy-Cl, Li-Y-Cl, Li-Er-Cl and Li-Tm-Cl solid electrolytes, about one order of magnitude increase in ionic conductivities are observed for the orthorhombic structure compared to the trigonal structure. Using the Li-Ho-Cl components as an example, detailed studies of its structure, phase transition, ionic conductivity, air stability and electrochemical stability have been made. Molecular dynamics simulations based on density functional theory reveal that the different cations arrangement in the orthorhombic structure leads to a higher lithium diffusivity as compared to the trigonal structure, rationalizing the improved ionic conductivities of the new Li-M-Cl electrolytes. All-solid-state batteries of In/Li2.73Ho1.09Cl6/NMC811 demonstrate excellent electrochemical performance at both room temperature and − 10°C. As relevant to the vast number of isostructural halide electrolytes, the present structure control strategy provides guidance for the design of novel halide superionic conductors.

Metal-N-decorated carbon catalysts are cheap and effective alternatives for replacing the high-priced Pt-based ones in activating the reduction of oxygen for metal–air or fuel cells. The preparation of such heterogeneous catalysts often requires complex synthesis processes, including harsh acid treatment, secondary pyrolysis processes, etching, etc., to make the heteroatoms evenly dispersed in the carbon substrates to obtain enhanced activities. Through combined experimental characterizations, we found that by precise control of the precursors added, a Fe/N uniformly distributed, agglomeration-free Fe/N decorated Super-P carbon material (FNDSP) can be easily obtained by a one-pot synthesis process with distinctly higher pyridinic-N content and elevated catalytic activity. An insight into this phenomenon was carefully demonstrated and also verified in Li–O2 batteries, which delivered a high discharging platform of 2.85 V and can be fully discharged with a capacity of 5811.5 mA h gcarbon+catalyst−1 at the cut-off voltage of 2.5 V by the low-cost Super-P modified catalyst.

Electrolyte is the key to constructing the ionic transport paths and O2 gas diffusion routes in the cathode as well as maintaining the electrode interfacial stability in view of the complex chemistry of Li–O2 batteries. A novel poly(vinyl formal) (PVFM)-based Janus membrane, which is prepared via coating multiwalled carbon nanotubes (MWCNTs) on the porous side of the cross-linked PVFM membrane, has been proposed herein to achieve membrane-supporting gel polymer electrolyte (GPE) for Li–O2 batteries. Within Li–O2 batteries, the dense side of PVFM-based Janus membrane demonstrates a good compatibility with lithium metal anode, while the other side with MWCNTs coating reserves much more solvent on the surface, assisting the cathode to form enlarged electrolyte-wetted interface. Moreover, the comparative studies indicate that PVFM-based Janus membrane also can provide a conductive pathway, modulate the morphology of the discharge products, and produce accommodation space for the products. So, the Li–O2 batter...

Lithium-rich layered oxides are promising cathode materials for high-energy-density lithium-ion batteries. However, the development of cathode materials based on these layered oxides has been limited by voltage fading, poor rate performance, and the low tap density of these materials. In this work, we prepared a material consisting of micrometer-scale spherical lithium-rich layered oxide particles with a three-dimensional conductivity network design and modified the surface of the primary particles with ruthenium. The as-obtained product with a maximum tap density of 2.1 g cm–3 shows a superior high reversible capacity with 280 mA h·g–1 at 0.1 C, a capacity retention of 98.1% after 100 cycles, and an outstanding rate capability. More importantly, enrichment of the primary particle surface with ruthenium can effectively suppress voltage decay. This cathode is feasible to construct high-energy and high-power lithium-ion batteries. This novel design may furthermore open the door to new material engineering a...

LiNi0.6Co0.2Mn0.2O2 (NCM) is a highly potential cathode material for lithium-ion batteries (LIBs). However, its poor rate capability and cycling performance at high cutoff voltages have seriously hindered further commercialization. In this study, we successfully design an ultra-thin lithium aluminum oxide (LiAlO2) coating on NCM for LIBs. Compared to Al2O3, the utilization of lithium-ion conducting LiAlO2 significantly improves the NCM performance at high cutoff voltages of 4.5/4.7 V. The study reveals that the LiAlO2-coated NCM can maintain a reversible capacity of more than 149 mA h g−1 after 350 cycles with 0.078% decay per cycle. Furthermore, LiAlO2-coated NCM exhibits higher rate capacities [206.8 mA h g−1 at 0.2 C (50 mA g−1) and 142 mA h g−1 at 3 C] than the Al2O3-coated NCM (196.9 mA h g−1 at 0.2 C and 131.9 mA h g−1 at 3 C). Our study demonstrates that the ultra-thin LiAlO2 coating is superior to Al2O3 and significantly improves the capacity retention and rate capability of NCM for LIBs.

All-solid-state lithium–sulfur batteries (ASSLSBs) are promising candidates as the power source for future electric vehicles due to their high energy density and superior safety properties. However, one of the major challenges of state-of-the-art ASSLSBs is related to the high interfacial resistance resulting from the instability between the solid-state electrolyte (SSE) and electrodes and/or the side reactions between polysulfides and SSE. Herein, we propose and demonstrate the significant enhancement of the cycling stability of an ASSLSB through atomic layer deposition interfacial engineering on the polymer/oxide ceramic/polymer sandwich-structured SSE. The results show that as few as 10 cycles of ALD Al2O3 on the LATP can endow ASSLSBs with a discharge capacity of 823 mA h g−1 after 100 charge/discharge cycles, which is almost two times higher than that of the ASSLSB without an ALD coating and that of a Li–S battery with a liquid-based electrolyte. Such improvement is attributed not only to the blocking of the polysulfide shuttling effect via the use of a sandwich SSE but also the significant reduction of the side reaction between the polysulfide and oxide ceramic SSE, which introduces high interfacial resistance and degrades the electrochemical performance. The protection role and mechanism of the ALD layer is also confirmed and revealed by XRD, SEM and XPS measurements.

Li-rich and Mn-based oxides (LRMO) have been an obvious choice of high specific energy batteries owing to their unique anion redox behavior based on the main component Li2MnO3. However, there are still electrochemical behaviors that cannot perfectly match the theoretical structure. So far, most theoretical research on LRMO has been carried out around the ideal Li2MnO3 structure. Nevertheless, there are a great number of non-ideal local configurations in the pristine materials under the case of practical situations. Herein, the ubiquitous complex local structures (defect-like) in the interior of Li2MnO3 particle, some of which have not been observed in the past, are directly presented through the atomic-level observation. We summarized these structures and proposed for the first time the great influence of these local structures on the electrochemical and the oxygen redox behavior of LRMO by combining observation, DFT calculation, XAS, XPS and electrochemical experiments. These micro-structures have been roughly divided into four categories by the advanced AC-STEM, including the so-called stacking faults caused by the slip of the adjacent TM layer, the local multi-Li or multi-Mn arrangement due to the combination of different stacking type along a–b plane, the expansion of the interlayer spacing, and even the distribution of polycrystalline domains, of which the second and third configurations were observed for the first time. These types of local structures dominate the electrochemical reaction of electrodes in some aspects by improving the activity of oxygen non-bonding 2p states, along with the improvement of (de)intercalation ability for Li ions in the bulk through reducing the energy barrier, and they are even one of the sources of voltage hysteresis by affecting the energy level distribution of oxygen unoccupied 2p states after delithiation. This research has perfected a more comprehensive and practical understanding of LRMO under the case of practical situations, laying a key foundation for the further modification and application of LRMO cathode materials.

Lithium-manganese-rich transition metal oxides have attracted substantial R&D attention due to their potential for high energy-density lithium-ion batteries. In this work, in situ high-energy X-ray diffraction was deployed to investigate the phase evolution during the solid-state synthesis of Li[Li0.2Mn0.54Ni0.13Co0.13]O2. A step-wise consumption of the starting materials was observed during the one-step heating process primarily due to the heterogeneous nature of the precursor. According to observations from in situ high-energy X-ray diffraction, a two-step process was adopted to minimize the elemental heterogeneity of the final product. The electrochemical characterization results showed a substantial improvement on the reversible specific capacity for the material synthesized through the two-step process.

To promote the development of solid-state batteries, polymer-, oxide-, and sulfide-based solid-state electrolytes (SSEs) have been extensively investigated. However, the disadvantages of these SSEs, such as high-temperature sintering of oxides, air instability of sulfides, and narrow electrochemical windows of polymers electrolytes, significantly hinder their practical application. Therefore, developing SSEs that have a high ionic conductivity (>10-3 S cm-1 ), good air stability, wide electrochemical window, excellent electrode interface stability, low-cost mass production is required. Herein we report a halide Li+ superionic conductor, Li3 InCl6 , that can be synthesized in water. Most importantly, the as-synthesized Li3 InCl6 shows a high ionic conductivity of 2.04×10-3 S cm-1 at 25 °C. Furthermore, the ionic conductivity can be recovered after dissolution in water. Combined with a LiNi0.8 Co0.1 Mn0.1 O2 cathode, the solid-state Li battery shows good cycling stability.

Li1.3Al0.3Ti1.7(PO4)3 (LATP) is a popular solid electrolyte used in solid-state lithium batteries due to its high ionic conductivity. Traditionally, the densification of LATP is achieved by a high-temperature sintering process (about 1000 °C). Herein, we report the compaction of LATP by a newly developed cold sintering process and post-annealing. LATP pellets are first densified at 120 °C and then annealed at 650 °C, yielding an ionic conductivity of 8.04 × 10-5 S cm-1 at room temperature and a relative density of 93% with a low activation energy of 0.37 eV. High-resolution transmission electron microscopy of the cold sintered pellets is investigated as well, showing that the particles are interconnected with some nanoprecipitates at the grain boundaries. Such nanocrystalline-enriched grain boundaries are beneficial for lithium-ion transportation, which leads to higher ionic conductivity of the cold sintered sample. This new sintering process can direct new horizons for development of all solid-state batteries due to its simplicity.

Solid-state lithium batteries (SSLBs) are the promising next-generation energy storage systems because of their attractive advantages in terms of energy density and safety. However, the interfacial engineering and battery building are of huge challenges, especially for stiff oxide-based electrolytes. Herein, we construct SSLBs by a cosintering method using Li

The pursuit of high energy density and safe lithium ion batteries (LIBs) is a urgent goal for the development of next-generation electric vehicles (EVs). All-solid-state batteries (ASSBs) with the combination of poly(ethylene oxide) (PEO)-based solid polymer electrolyte (SPE) and Ni-rich lithium nickel manganese cobalt oxide LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode are promising candidates for EVs due to their improved energy density and safety. However, the low electrochemical oxidation window of PEO-based SPE and the instability of NMC811 at the charge/discharge process seriously restrict the battery performance. Herein, a high voltage stable solid-state electrolyte layer lithium niobium oxide (LNO) is coated on the NMC811 electrode surface by atomic layer deposition for stabilizing NMC811-PEO solid polymer batteries. Electrochemical tests show that LNO coating can stabilize the NMC811 active materials and mitigate the decomposition of SPE upon the cycling process, rendering a good performance of NMC811-PEO solid polymer battery. Mechanism studies by SEM, STEM, XAS, and XPS disclose that the uncoated NMC811 suffers from chemomechanical degradations along with oxygen release triggering the decomposition of SPE, which results in unstable cathodic electrolyte interphase. With LNO coating, chemomechanical degradations and oxygen release are inhibited and the decomposition of SPE is mitigated. This work renders a stable and high-performance high-energy-density SSB for high voltage application, which paves the way toward next-generation solid-state LIBs.

A new positive temperature coefficient (PTC) electrode is prepared simply by coating a thin layer of redox-active poly (3-butylthiophene) (P3BT) in between the electroactive Li[Ni 0.5 Co 0.2 Mn 0.3 ]O 2 [523] layer and the Al foil substrate to improve the safety of lithium-ion batteries. The experimental results demonstrate that the electrical conductivity of the PF 6 − -doped P3BT decreases sharply at 120–150 °C, showing a remarkable PTC effect. As for the P3BT-523 composite electrodes, a rate capacity nearly reaching the reference electrode is obtained at less than 1C rate, while the rate discharge capacities increase obviously with the decrease of the P3BT solution concentration. Moreover, after being exposed to 150 °C for 5 min, the P3BT-523 composite electrodes are hardly discharged and the discharge voltage of the composite electrodes drop drastically below the cut-off voltage at a current density of 3 C, suggesting an effective thermal shutdown switch for lithium-ion batteries.

Silicon nanowires (SiNWs) were produced by the electrochemical reduction of porous NiO/SiO 2 blocks ([SiO 2 ]/[NiO]=10 M ratio) in molten CaCl 2 at 1173 K for the first time. NiO additives seed the growth of straight SiNWs. The produced SiNWs have diameter distributions ranging from 60 to 330 nm and outer amorphous layers with thickness about 2.5–3.1 nm. The length of the nanowire can be as long as 30 µm. The high length-to-diameter suggests that silicon is incorporated through the tip of the nanowire. Nano-sized nickel silicide particles are observed in the body of a zigzag SiNW. The results indicate that the electrochemical reduction process has the potential to produce nano-sized Si-based composite and metal silicide.

Advancement of all-solid-state lithium-ion (Li+) batteries (ASSLIBs) has been hindered by the large interfacial resistance mainly originating from interfacial reactions between oxide cathodes and solid-state sulfide electrolytes (SEs). To suppress the interfacial reactions, an interfacial coating layer between cathodes and SEs is indispensable. However, the kinetics of interfacial Li+ transport across the coating layer has not been well understood yet. Herein, we tune the interfacial ionic conductivity of the coating layer LiNb0.5Ta0.5O3 (LNTO) by manipulating post-annealing temperature. It is found that the interfacial ionic conductivity determines interfacial Li+ transport kinetics and enhancing the interfacial ionic conductivity can significantly boost the electrochemical performance of SE-based ASSLIBs. A representative cathode LiNi0.5Mn0.3Co0.2O2 coated by LNTO with the highest interfacial ionic conductivity exhibits a high initial capacity of 152 mAh.g−1 at 0.1 C and 107.5 mAh.g−1 at 1 C. This work highlights the importance of increasing interfacial ionic conductivity for high-performance SE-based ASSLIBs.

Chemical activation of Li-rich layered oxide (LLO) is an effective way to mitigate the intrinsic drawbacks of LLO. Herein, the Li-rich layered material 0.25Li2MnO3·0.75LiMn0.42Ni0.48Co0.1O2, which has a relatively higher Ni content, is treated with a common reducing substance sodium thiosulfate (Na2S2O3) over a wide range of heating temperature (300 °C, 500 °C, 750 °C). The experimental results demonstrate that: (1) Na2S2O3 can successfully pre-activate LLO by extracting Li+ out of the material to form LiNaSO4, (2) the pre-activated material shows a high correlation with the heating temperature of this treatment, that is, with the increase of heating temperature from 300 °C to 750 °C the spinel-to-layered phase transition takes place in the particle surface region. This unusual structural evolution is in fact associated with the enrichment of Ni element in particle surface region, meanwhile leads to a remarkable improvement of each electrochemical performance. Hence, this high temperature surface treatment by Na2S2O3 is anticipated to be an effective strategy to pre-activate the Li-rich layered material so that overcomes its intrinsic drawbacks to some extent.