Multiband Spectrum Method for Quantifying the Ionic Contribution of Volume Strategy and Filler Strategy: Enhancing the Ionic Transport Channels for Polymeric Solid-State Batteries

As a promising solution for solid-state batteries with high energy density and safety, understanding the mechanism of fast ion conduction in polymer-ceramic composite solid-state electrolytes (CSEs) is still a challenging task. Herein, we understand the enhanced ion conduction in CSEs using a series of ionic spectra. Ionic insight is extended to ion conduction in CSEs, resolving the mechanism of fast ion migration. With the cooperation of enhanced interface and filler ion conduction, the CSE with a conductive filler exhibits ionic conductivity higher than that of CSEs with insulating fillers. Volume and filler strategies of CSE design are proposed based on volcanic maps of conductivity. An equivalent circuit is established to describe the conduction mechanism of CSEs. Specifically, R_interface and R_filler are in parallel to describe the cooperation of interface and filler conduction. They are in series with R_bulk, which represents a competition between the fundamental matrix and enhanced interface conduction. The proposed conduction model is verified though the energy storage performance of solid-state batteries; a fast dynamic process promises a better rate performance and cycling stability of solid-state batteries. These results provide deep insights into fast ion conduction in ceramic-polymer CSEs, which are indispensable to develop high-performance solid-state batteries.