Electrolyte-Dependent Pressure Sensitivity Governs Lithium Deposition Stability in Lithium Metal Batteries.

Abstract

Stack pressure is widely recognized as an effective strategy for regulating lithium (Li) deposition in Li metal batteries, yet its electrolyte-dependent effect and underlying mechanisms remain unclear. Here, we systematically investigate electrolyte-dependent pressure sensitivity of Li deposition across conventional and advanced electrolytes. We demonstrate that pressure sensitivity originates from the intrinsic morphology of early-stage Li deposition. Electrolytes forming porous, filamentary Li exhibit strong pressure responsiveness, whereas those promoting bulk-like Li maintain stable cycling over a wide pressure range. Coupled electrochemical-mechanical modeling reveals that dendritic morphologies induce stress concentration that activates creep-driven lateral Li redistribution under compression, while bulk deposits generate homogeneous stress fields and therefore weak pressure sensitivity. Extending these insights to anode-free pouch cells, we introduce a quantitative pressure sensitivity descriptor and identify electrolyte-specific optimal stack pressures. These findings establish stack pressure as an electrolyte-dependent design parameter and provide mechanistic and engineering guidelines for achieving stable Li metal batteries.