Pressure–Temperature Regulation of Chemo-Mechanical Degradation in Ni-Rich Composite Cathodes for All-Solid-State Batteries

Abstract Achieving high charge capacity and maintaining mechanical integrity remain challenging for Ni-rich NMC composite cathodes in sulfide-based all-solid-state batteries because of particle cracking and interface debonding, yet how operating conditions govern these competing failure processes remain unclear. Here, we develop an experimentally benchmarked electrochemical–mechanical–fracture phase-field framework to resolve reaction kinetics, anisotropic Li-ion transport, particle cracking, and interfacial debonding during high-voltage delithiation. The simulations reveal an inward-to-outward failure sequence: crystallographic anisotropic strain first initiates particle cracking, thus crack extension and particle contraction promote interface debonding, with the H2–H3 transition accelerating solid–solid contact loss, thereby reducing electrochemical accessibility. Stack pressure monotonically suppresses interfacial debonding and improves specific charge capacity by preserving interface contact and reducing polarization, but pressures above approximately 30 MPa intensify intraparticle stress accumulation and cracking. Increasing temperature enhances interfacial charge transfer and solid-state Li-ion transport, improving capacity utilization, while aggravating mechanical damage through deeper delithiation and lattice contraction. By simultaneously constraining specific charge capacity, particle cracking, and interfacial debonding, a representative operating window of approximately 30–70 MPa and 20–50 °C is identified for this idealized configuration. These results establish mechanistic relationships and qualitative regulatory trends among operating conditions, charge capacity, and mechanical degradation, providing a methodological framework for high-capacity and mechanically robust Ni-rich composite cathodes in all-solid-state batteries.