Intrinsic Mechanical Parameters and their Characterization in Solid‐State Lithium Batteries

Abstract The most critical failures in solid‐state batteries, including interfacial detachment, cracks, and dendrite growth are coupled with or fundamentally belong to a class of overarching phenomena that may be broadly defined as mechanical processes. However, current research on mechanical processes is far from sufficient, and is in its infancy compared with studies of improving electrolyte ionic transportation and electrochemical stabilities. Even the physical significance of many mechanical parameters has not been clarified in this field and the corresponding characterization methods have not yet been widely established. Herein, this review focuses on the intrinsic mechanical parameters associated with the design and operation of solid‐state batteries and their characterization. Beginning with an overview of mechanical processes, key concepts in the context of solid‐state batteries (SSB) are defined. Next, the various characterization methods that have been applied to SSBs are described in detail, and the key results are reviewed. Additional methods applied in orthogonal areas are also included to emphasize the possible translational impact on the solid‐state battery field. Finally, perspectives on the challenges and development trends in mechanical characterization are proposed for further development in solid‐state batteries.