The utilization of sulfide-based solid electrolytes represents an attractive avenue for high safety and energy density all-solid-state batteries. However, the potential has been impeded by electrochemical and mechanical stability at the interface of oxide cathodes. Plastic crystals, a class of organic materials exhibiting remarkable elasticity, chemical stability, and ionic conductivity, have previously been underutilized due to their susceptibility to dissolution in liquid electrolytes. Nevertheless, their application in all-solid-state batteries presents a paradigm that could potentially overcome longstanding interface-related obstacles. This study presents a facile approach to enhancing the performance of sulfide-based solid-state batteries by utilizing nickel-rich oxide cathodes coated with ionically conductive plastic crystals. For employing plastically deformed succinonitrile as a metal ion ligand, it simultaneously supports mechanical stability and interfacial conduction, while LiDFOB establishes moderate ionic conductivity and a stable cathode electrolyte interphase (CEI). The synergistic effects of these mechanisms culminate in remarkable long-term performance metrics, with the capacity retaining 80% after 1529 cycles. Furthermore, this stability is maintained even when the areal capacity density is increased to a substantial 3.53 mA h cm-2. By combining electrochemical stability with mechanical plasticity, this approach opens possibilities for the development of long-lasting solid-state batteries suitable for practical applications.
Keywords: argyrodite solid-state electrolyte; electrochemical stability; mechanical stability; nickel-rich cathode; plastic crystal.