Improving the energy density of all-solid-state batteries by maximizing the contact area between the solid electrolyte and electrode, and stress issues

Solid-state electrolyte batteries are excellent candidates for the development of safe and high-performance lithium batteries. However, the low ionic conductivity and poor interfacial contact of current solid-state electrolytes severely hinder the commercialization of solidstate batteries. Moreover, a higher stress is caused by the use of solid-state electrolytes compared with that in the case of liquid electrolytes. To increase the physical contact area between the solid/solid interfaces of all-solid-state batteries (ASSBs), this study constructed two types of interfaces with sine-curved and trapezoidal shapes to replace the general planar interface and used the Nelder-Mead algorithm to optimize the curved interface and geometric parameters of the battery cells. ASSBs are composed of a sulfide-based LI6PS5Cl solid electrolyte, a low-density lithium metal anode, and a high-theoretical-capacity LCO cathode. The optimization results show that the curved interface can achieve a higher energy density than a flat-interface battery. The stress caused by lithium deposition during battery charging was also calculated. The low modulus of the soft solid electrolyte significantly reduced the stress inside the battery.