An ionically conductive and compressible sulfochloride solid-state electrolyte for stable all-solid-state lithium-based batteries

Halide electrolytes, renowned for their excellent electrochemical stability and wide voltage window, exhibit significant potential in the development of high energy density solid-state batteries featuring high voltage cathode materials. In this study, we present the development and synthesis of a 0.6Li₂S-ZrCl₄ solid electrolyte, demonstrating an ion conductivity of 1.9 × 10^–3 S/cm at 25 °C. Under a pressure of 500 MPa, the relative density of the electrolyte can reach 97.37%, showcasing its commendable compressibility. 0.6Li₂S-ZrCl₄ served as the electrolyte, and we assembled batteries utilizing a LiCoO₂ (LCO) positive electrode, Li_9.54Si_1.74P_1.44S_11.7Cl_0.3 (LSPSCl) coating, and Li-In negative electrode for laboratory testing. At 25 °C, this all-solid-state battery demonstrated an impressive discharge capacity retention rate of 86.99% (with a final discharge specific capacity of 110.5 mAh/g) after 250 cycles at 24 mA/g and 100 MPa stack pressure. Upon substituting the positive electrode material with LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) and assembling an all-solid-state battery, it demonstrated a discharge capacity retention rate of 74.17% after 200 cycles at 3.6 mA/g and 100 MPa stack pressure in an environment at 25 °C (with a final discharge specific capacity of 103.3 mA/g). Our findings hold significant implications for the design of novel superionic conductors, thereby contributing to the advancement of all-solid-state battery technology.