context: Both chemical and mechanical instabilities play a role in the impedance build-up and capacity fade during SSB cycling. Chemical reactivity issues between conductor and cathode have been well-studied theoretically and experimentally. In this work, we focus on the mechanical failure modes of an SSB composite cathode. The latter consists of an intimate mixture of the solid electrolyte and active cathode particles so that a transport path exists for the Li ions to/from the cathode particles. Good Li-ion transport across the solid electrolyte/cathode particle interface is necessary to minimize the cell resistance and overpotential of the composite cathode. Chemical reactivity at the solid electrolyte/cathode interface can lead to the formation of a reaction layer, which increases cathode impedance. For example, sulfide-based electrolytes have been shown to react with oxide-based cathodes, resulting in overpotential growth and capacity fade. Coating the cathode particles has been shown to mitigate this issue to some extent and improve cycling stability.
answer: SSB composite