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

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.