Enhancing electrochemomechanics: How stack pressure regulation affects all-solid-state batteries

Stack pressure application in solid-state batteries (SSBs) is crucial for achieving high-energy density by promoting interfacial contact. Fluctuations in stack pressure at the MPa-scale can result in mechanical fatigue, leading to the degradation of materials within a fixed-volume cell casing. Thus, it is essential to regulate these stack pressure variations during cycling. In this study, we successfully stabilize the evolution of stack pressure at the hundred kPa-scale by incorporating compression springs into the conventional SSB assembly. This kPa-level stabilization is achieved by converting elastic potential energy into spring deformation. We investigate these mechanical responses by correlating them with stack pressure and cell thickness measurements in a variable volume cell. Furthermore, accommodating volume changes results in more than 98% retention of the highest stack pressure retention. These findings can significantly contribute to advancements in cell assembly processes critical for scaling up SSB modules.