Understanding Key Limiting Factors of Electrode and Cell Designs in Solid-State Lithium Batteries

Abstract

Solid-state batteries (SSBs) use solid electrolytes (SE) to replace flammable liquid electrolytes that result in safer batteries with increased energy density enabled by lithium metal as an anode. Even though there have been recent major breakthroughs at the material level and some at the cell level, there are still many more challenges to overcome that are mostly related to the solid-solid interfaces besides the grand challenge of manufacturing these type of batteries with or without existing manufacturing processes with the promised energy density ( > 400Wh/Kg) at targeted low costs (< 100$/KWh). For this to happen, it is important to look into all the changes that need to be made at the material, electrode and cell levels compared to what is currently used in Li-ion cells and critically evaluate their impact on the cell energy density. In this work, we have first used an equation that we have previously modified and used to calculate the impact of Si content in Si-graphite composite on the full-cell energy density (2) to evaluate the impact of the following parameters (type of anode-or no anode- and cathode materials. N/P ratio, thickness of SE and most importantly the composite cathode formulation on the full-cell energy density. In the latter, we have evaluated the thickness of two electrodes, amount and volume of cathode active material, and amount of catholyte). We will present the impact of each of the above-mentioned factors on the cell energy density supported by data from half and full cells using composite cathodes coupled with and without lithium metal as an anode.