Harnessing High‐Pressure CO ₂ 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 CO 2 to in situ engineer the Li 6 PS 5 Cl (LPSC) surface. Through precise regulation with concentrated CO 2 molecules, a nanoscale Li 2 CO 3 ‐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 0.8 Co 0.1 Mn 0.1 O 2 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.