High Configuration Entropy Promises Electrochemical Stability of Chloride Electrolytes for High-Energy, Long-Life...

Solid-state electrolytes (SSEs) with high ionic conductivity, stability, and interface compatibility are indispensable for high-energy-density and long-life all-solid-state batteries (ASSBs), yet there are scarce SSEs with sufficient ionic conductivity and electrochemical stability. In this study, with a high-entropy SSE (HE-SSE, Li_2.9In_0.75Zr_0.1Sc_0.05Er_0.05Y_0.05Cl₆), we show the high configuration entropy has a thermodynamically positive relationship with the high-voltage stability. As a result, the ASSBs with HE-SSE and high-voltage cathode materials exhibit superior high-voltage and long-cycle stability, achieving 250 cycles with 81.4 % capacity retention when charged to 4.8 V (vs. Li⁺/Li), and even 5000 cycles if charged to 4.6 V (vs. Li⁺/Li). Experimental characterizations and density functional theory calculations confirm that the HE-SSE greatly suppresses the high-voltage degradation of SSE at the interface, promoting the high-voltage stability coordinately through high entropy and interface stability. The high entropy design offers a general strategy to simultaneously improve the high-voltage stability and ionic conductivity of SSEs, creating an avenue to building high-energy and long-life ASSBs.