Flexible Nanowire Cathode Membrane with Gradient Interfaces and Rapid Electron/Ion Transport Channels for Solid‐State Lithium Batteries

Abstract Solid‐state lithium batteries (SSLBs) have attracted more attention due to their improved safety and high energy density. Although numerous solid‐state electrolytes (SSEs) with high ionic conductivity have been frequently reported, poor solid–solid interfacial contact and interfacial chemical reactions around the cathode in SSLBs can hinder their practical application. Here, a gradient nanowire (NW) cathode is demonstrated for advanced interface engineering in SSLBs by a facile solvent evaporation process. In this unique gradient cathode membrane, one side surface with more ionic conductive polymer provides a smooth contact with SSE, while the other side surface with more electronic conductive NW/reduced graphene oxide composite provides rapid electron transport acting as a current collector. Furthermore, the inside NW cathode materials are uniformly coated by a solid polymer electrolyte and such a structure changes the point‐to‐point contact to a large‐area contact in the cathode, providing continuous channels for rapid electron/ion transport and improved mechanical strength. The effective interface engineering gives SSLBs enhanced structural stability and excellent electrochemical performance. The as‐obtained SSLBs can deliver 200 mAh g –1 capacity after 100 cycles at room temperature without obvious structural degradation. This novel design of NW‐based gradient cathodes demonstrates a promising strategy for solid–solid interface engineering in solid‐state lithium batteries.