The Intercorrelations of Mechanical Properties in Composite Solid Electrolytes and Their Decisive Role in Cells’ Cycling Life

With deepening research on solid electrolytes, mechanical properties have been recognized to impact significantly on cells' performances and need to be intentionally enhanced. However, the intercorrelation of mechanical parameters and their modifications is still poorly understood. In this study, comprehensive mechanical characterizations are conducted on a series of typical PEO/LLZTO composite electrolytes. Each mechanical parameter under different deformation processes is obtained, including tensile, fracture, puncture, lap-shear, adhesion, and indentation. For the first time, change trends of these parameters are observed to reveal their intercorrelations. Interestingly, the mechanical resistances (elastic modulus, hardness, fracture energy, and puncturing force) could be adjusted toward the same direction, whereas the adhesive behaviors (shear strength and adhesion force) show an opposite trend. The mechanical resistance parameters show a decisive effect on the cell's cycling time, when they have a contradictory tendency with ionic conductivity. Also, different influences of synthesis conditions on mechanical properties are investigated systematically.