Dual-functional interfaces for highly stable Ni-rich layered cathodes in sulfide all-solid-state batteries

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.