Mechano-Electrochemical Phenomena in Solid-State Batteries

There is tremendous interest in making the next super battery, however Li ion technology continues to improve and has inertia in several commercial markets. Recent material breakthroughs in solid-electrolytes (SE) could enable a new class of non-combustible solid-state batteries delivering twice the energy density (&gt;1,300 Wh/L) compared to Li-ion. However, technological and manufacturing challenges remain, creating the impetus for fundamental and applied research.<br/><br/>This discussion will consist of fundamental aspects such as the mechano-electrochemical phenomena at solid interfaces as well as manufacturing challenges related to the integration of Li metal electrodes. The underlying physics that control the stability and kinetics of Li/SE interfaces are fundamentally different from interfaces in Li ion technology. Moreover, the mechano-electrochemical phenomena that occur during discharge and charge at the Li/SE interface are considerably different. For example, during charging at higher rates Li metal filaments can initiate at defects and propagate through relatively hard ceramics. During discharge, if the Li stripping rate is sufficiently high and the temperature is sufficiently low, voids form at the interface causing delamination at of the interface.<br/><br/>In another example, novel mechano-electrochemical phenomena are emerging when analyzing the formation of Li anodes in using the Li⁰-free manufacturing approach. Using this approach for solid-state batteries, Li metal in interposed between a current collector and the SE. The mechanics at this interface will determine the feasibility of this approach by controlling the homogeneity of the <i>in situ</i> formed Li anode. While significant progress is advance the technological maturity of solid-state batteries, there remain fundamental questions regarding the physics at interfaces and whether or not they exhibit sufficient stability and kinetics that are relevant to EVs.