A novel asymmetrical multilayered composite electrolyte for high-performance ambient-temperature all-solid-state lithium batteries

All-solid-state lithium batteries are considered promising next-generation devices for energy storage, but their application still faces various interfacial issues. In this work, an innovative asymmetric multi-layered solid composite electrolyte design is proposed to satisfy the distinctive demands of the cathode and anode simultaneously. A composite electrolyte consisting of poly(ethylene oxide) and Li6.4La3Zr1.4Ta0.6O12 is employed as the intermediate layer to provide sufficient mechanical strength, while a poly(ethylene oxide) buffer layer with high flexibility contacts with the cathode and poly(propylene carbonate) polymer contacts with the anode to reduce interfacial resistance. The enhanced interfacial contact induces the formation of a dense and uniform LiF-rich cathode electrolyte interface film, and the components derived from a poly(propylene carbonate) reaction with Li promotes the solid electrolyte interphase film formation of inorganic lithium species to improve the interface stability. This ingenious design enables sustained cycling of LiFePO4 and LiNi0.6Co0.2Mn0.2O2 based solid-state cells at room temperature, offering a promising avenue for the advancement of high-energy density and safe lithium batteries in the future. A novel MSCE is designed by introducing a PEO layer against the cathode and a "self-sacrifice" PPC layer against the anode.