Composite Cathodes with Succinonitrile‐Based Ionic Conductors for Long‐Cycle‐Life Solid‐State Lithium Metal Batteries

Abstract

AbstractPoor interfacial contacts between cathode active materials and solid‐state electrolytes in solid‐state lithium (Li) metal batteries often lead to a poor Li‐ion conductive pathway, and thus a short cycle life and a low energy density. In this work, we synthesized succinonitrile (SCN)‐based ionic conductors (ICs) with different flowability at room temperature for using in the composite cathodes and investigated the effect of the ICs on the cycle performance of the solid‐state Li metal batteries with a poly(vinylidene fluoride) (PVDF)‐based polymer electrolyte separator. Our results showed that the gel‐like SCN‐LiClO4 IC was superior to the flowable SCN‐LiTFSI [lithium bis(trifluoromethanesulfonyl)imide] IC and the rigid SCN‐LiClO4 IC. The gel‐like IC can build an effective Li‐ion conduction path in the cathodes, establish a stable cathode/electrolyte interface with a small interfacial resistance change during cycling, and allow a high mass loading of active materials, which enables a long cycle life and high energy density of solid‐state batteries.