Improvement of All Solid-State Lithium Metal Battery Performance with Sulfide and Oxide Electrolyte by Shot Peening

The all solid-state lithium metal battery is considered a promising technology for electric vehicles due to its high theoretical capacity. However, during fast charging, the growth of lithium dendrites causes internal short circuits, which limits the charging rate. This study investigates the fast charging performance of sulfide and oxide solid electrolytes, which are representative solid electrolytes, by suppressing crack formation in the electrolyte through shot peening. The results show that shot peening did not increase the charging rate of sulfide solid electrolytes, but increased it by 10 times in the case of oxide solid electrolytes. Shot peening increased the fracture toughness of the oxide solid electrolyte by about 2 times, which is believed to have contributed to the increase in charging rate. The difference in the results for the sulfide and oxide solid electrolytes is due to the difference in their pellet production process. The oxide solid electrolytes are produced by high-temperature sintering, which results in compressive residual stresses that increase fracture toughness when shot peening is performed. However, the sulfide solid electrolytes are formed into pellets by cold pressing, and sintering is not performed after pressing, so there is residual stress by the pressing, resulting in no increase in fracture toughness due to shot peening.