Pressure-Driven Performance and Thermal Safety Tradeoff in Solid-State Batteries

Abstract Solid-state batteries (SSBs) offer high energy density and improved safety, but their performance is limited by poor particle contact and sluggish ion transport across solid–solid interfaces. External pressure improves electrochemical performance by enhancing interfacial contact and reducing resistance; however, its impact on thermal behavior and safety remains unclear. Here, we investigate how pressure influences the thermal response of composite solid-state cathodes and its implications for cell-level safety. Over 0–70 MPa, increasing pressure enhances capacity but induces a nonmonotonic thermal response governed by the balance between reduced heat generation and extended discharge duration. Pressure consistently improves thermal efficiency by lowering the heat-to-capacity ratio. Incorporating a self-heating onset criterion, we quantify thermal runaway risk and identify performance-safety trade-offs that evolve with pressure, C-rate, and cathode thickness. These results provide design guidelines for pressure-optimized, thermally stable SSBs for high-power and high-energy applications.