All-solid-state lithium batteries (ASSLBs) have attracted great interest due to their promising energy density and strong safety. However, the interface issues, including large interfacial resistance between electrode and electrolyte and low electrochemical stability of solid-state electrolytes against high-voltage cathodes, have restricted the development of high-voltage ASSLBs. Herein, we report an ASSLB with stable cycling by adopting a conformal polymer interlayer in-situ formed at the Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO)–cathode interfaces. The polymer can perfectly fill the voids and create a stable interface contact between LLZTO and cathodes. In addition, the electric field across the polymer interlayer is reduced compared with pure solid polymer electrolyte (SPE), which facilitates the electrochemical stability with high-voltage cathode. The all-solid-state Li|LLZTO-SPE|LiFe_0.4Mn_0.6PO₄ (LMFP) cells achieve a low interface impedance, high specific capacity, and excellent cycling performance. This work presents an effective and practical strategy to rationally design the electrode–electrolyte interface for the application of high-voltage ASSLBs.

Garnet-type oxide is one of the most promising solid-state electrolytes (SSEs) for solid-state lithium-metal batteries (SSLMBs). However, the Li dendrite formation in garnet oxides obstructs the further development of the SSLMBs seriously. Here, we report a high-performance garnet oxide by using AlN as a sintering additive and Li as an anode interface layer. AlN with high thermal conductivity can promote the sintering activity of the garnet oxides, resulting in larger particle size and higher relative density. Moreover, Li₃N with high ionic conductivity formed at grain boundaries and interface can also improve Li-ion transport kinetics. As a result, the garnet oxide electrolytes with AlN show enhanced thermal conductivity, improved ionic conductivity, reduced electronic conductivity, and increased critical current density (CCD), compared with the counterpart using Al₂O₃ sintering aid. In addition, Li symmetric cells and Li|LiFePO₄ (Li|LFP) half cells using the garnet electrolyte with the AlN additive exhibit good electrochemical performances. This work provides a simple and effective strategy for high-performance SSEs.

Lithium-ion batteries are considered a promising energy storage technology in portable electronics and electric vehicles due to their high energy density, competitive cost, and environmental friendliness. Improving cathode materials is an effective way to meet the demand for better batteries, of which the utilization of high-voltage cathode materials is an important development trend. In recent years, lithium-rich layered oxides have gained great attention due to their desirable energy density. This review presents the relationships between lattice structure and electrochemical properties, the underlying degradation mechanisms, and corresponding modification strategies. The recent progress and strategies are then highlighted, including element doping, surface coating, morphology design, size control, etc. Finally, a concise perspective for future developments and practical applications of lithium-rich layered oxides has been provided.

Garnet-type oxide solid electrolytes are the critical materials for all-solid-state lithium ion batteries. Nanoscale spectroscopic analysis on solid electrolytes plays a key role in bridging the gap between microstructure and properties. In this work, Auger electron spectroscopy (AES), which can directly detect lithium element and distinguish its valence state, was applied to characterize the garnet-type Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO). Different spectroscopy parameters were evaluated and optimal acquisition conditions were provided. Electron induced precipitation of lithium metal from LLZTO was observed. By exploring the influence factors of precipitation and combining transmission electron microscopy (TEM) and focused ion beam (FIB) experiments, the underlying mechanism of the phenomenon was revealed and previous controversy was resolved. The analysis method was also extended to other types of solid electrolytes, and this work provides a reference for future in-depth research on the structure–property relationship of solid electrolytes using AES.