Ni-rich layered oxide cathodes can yield substantial increase in energy density of solid-state Li-ion batteries, but they suffer from contact loss, and irreversible layered-to-spinel or disordered rock-salt-like phase transition . These structural degradation mechanisms have been mainly attributed to oxygen loss and out-of-plane transition metal (TM) migration arising from cathode/electrolyte interfacial side reactions . Cathode particle surface modification or coating techniques could partially alleviate interfacial degradation , however, the effectiveness of these strategies has proven insufficient to mitigate structural degradation in the bulk of cathode materials . This dilemma raises the suspicion that the electrochemical instability of the cathode/electrolyte interface may not be the main cause behind the progressive capacity degradation observed over cycling. One of the critical aspects of solid-state batteries is the stress response of their complex microstructure to large volume changes (strains) driven by Li intercalation.