Understanding the Limitations of Solid-State Lithium Batteries for Electric Vehicles

Abstract

The market penetration of electric vehicles is hindered by their safety issues and limited driving range, due to the intrinsic instability of liquid electrolytes as well as the low capacity of insertion materials used in lithium-ion technology. Solid electrolyte, including solid polymer electrolyte, inorganic solid electrolyte as well as hybrid electrolytes, provide a solution to these barriers owing to the promise of better safety and the compatibility with Li metal (higher energy density). In the past several decades, tremendous efforts have been made to increase the ionic conductivity of the solid electrolytes. However, it is still not clear if the properties of presently available solid electrolytes are sufficient to meet the targets for electric vehicle batteries. Therefore, there is a need to correlate the electrolyte properties at the material level to battery targets at the cell and system level. In this study, we present a material-to-cell level analysis of solid electrolytes. Continuum electrochemical models are used to project energy and power capabilities of solid-state cells based on their material properties. The models use appropriate material properties, where available, and compared to experimental data to ensure validity. The validated model is then used to estimate the cell-level energy and power capability following the testing protocols targeting electric vehicles application. This analysis helps to identify existing challenges and provides guidelines for research at both material and cell levels for this promising class of next-generation batteries.