Harnessing High-Pressure CO₂ for Molecular-Scale Interfacial Engineering in Sulfide-Based All‑Solid‑State Lithium Metal Batteries.

Abstract

The rapid expansion of the low-altitude economy has intensified the demand for energy storage with exceptional rate capability. Sulfide electrolytes, with high room-temperature ionic conductivity and processability, are pivotal for next-generation all-solid-state batteries (ASSBs), but their interfacial instability and the resulting low critical current density severely hinder high-rate performance. Here, we propose a molecular-level interfacial construction strategy using high-pressure CO₂ to in situ engineer the Li₆PS₅Cl (LPSC) surface. Through precise regulation with concentrated CO₂ molecules, a nanoscale Li₂CO₃-rich layer with high Young's modulus and superior oxidant‑resistance is constructed. This designed interphase effectively suppresses parasitic reactions, enhances mechanical integrity, and homogenizes Li-ion flux. Consequently, the modified LPSC exhibits exceptional dendrite-suppression capability, achieving a critical current density of 7.76 mA cm^-2, and enables stable Li plating and stripping over 920 h at 5 mA cm^-2 in symmetric cells. Furthermore, full cells paired with a high-voltage LiNi_0.8Co_0.1Mn_0.1O₂ cathode demonstrated outstanding rate capability at 5C with a power density of 3160 W kg^-1 and maintained stable cycling over 500 cycles at 0.5C. This work proposes a simple and effective molecular-scale interface engineering method to overcome the power limitation problem of sulfide-based ASSBs.