Interphase-Adaptive Chloride Solid Electrolyte Enables High-Performance All-Solid-State Lithium Batteries

Halide solid electrolytes offer a compelling combination of wide electrochemical stability and high safety for all-solid-state lithium batteries (ASSLBs), yet their practical application is severely hindered by interfacial degradation, mechanical contact loss, and low active-material utilization when paired with Ni-rich layered oxide cathodes. Here we synthesize a monoclinic Li2.4Yb0.4Zr0.6Cl6 (LYZC) with a high ionic conductivity of 2.1 × 10–3 S·cm–1 at 30 °C, and then coat it with an ultrathin amorphous organic interphase (LYZC@CH) through an organic-solvent-assisted low-temperature strategy. The adaptive organic interphase transforms the intrinsically rigid chloride electrolyte into a chemo-mechanically compliant ion conductor that accommodates cathode volume variation while preserving rapid lithium–ion transport. Consequently, the engineered electrolyte stabilizes the cathode/electrolyte interface, suppresses parasitic interfacial reactions and structural degradation, and enables composite cathodes with a high active-material content of 90%. The resulting LiNi0.83Co0.12Mn0.05O2 composite cathode delivers an electrode-level energy density of 402.22 Wh kg–1 and retains nearly 100% of its capacity after 2000 cycles at 5 C in 30 MPa. This work establishes an electrolyte-centered interfacial engineering strategy for practical high-energy all-solid-state lithium batteries.