Determining the Role of Ion Transport Throughput in Solid‐State Lithium Batteries

Abstract Solid‐state lithium metal batteries (SSLMBs) are promising candidates for high‐energy‐density energy storage devices. However, there still lacks an evaluation criterion to estimate real research status and compare overall performance of the developed SSLMBs. Herein, we propose a comprehensive descriptor, Li + transport throughput ( ), to estimate actual conditions and output performance of the SSLMBs. The is defined as molar number of Li + passing through unit area of electrode/electrolyte interface in an hour (mol m −2 h −1 ) during cycling of battery, which is a quantizable value after taking complex aspects including cycle rate, electrode areal capacity and polarization into account. On this basis, we evaluate the of liquid, quasi‐solid‐state and solid‐state batteries, and highlight three key aspects to achieve high value of via building highly efficient cross‐phase, cross‐gap and cross‐interface ion transport in the solid‐state battery systems. We believe that the new concept of provides milestone guidelines towards large‐scale commercialization of SSLMBs.