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

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 ( phi Li+), to estimate actual conditions and output performance of the SSLMBs. The phi Li+ 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 phi Li+ of liquid, quasi-solid-state and solid-state batteries, and highlight three key aspects to achieve high value of phi Li+ 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 phi Li+ provides milestone guidelines towards large-scale commercialization of SSLMBs.

Automated summary

Solid-state lithium metal batteries (SSLMBs) are potential candidates for high-energy-density energy storage devices. However, there is a lack of evaluation criterion to assess the research status and overall performance of SSLMBs. In this study, a comprehensive descriptor called Li+ transport throughput (phi Li+) is proposed to estimate the actual conditions and output performance of SSLMBs. The phi Li+ is defined as the molar number of Li+ passing through the electrode/electrolyte interface per unit area in an hour (mol m(-2) h(-1)), considering the cycle rate, electrode areal capacity, and polarization. The phi Li+ of liquid, quasi-solid-state, and solid-state batteries are evaluated, and three key aspects are highlighted to achieve a high value of phi Li+ in solid-state battery systems through efficient ion transport across phases, gaps, and interfaces. The concept of phi Li+ provides important guidelines for the large-scale commercialization of SSLMBs.