High-Entropy Laminates with High Ion Conductivities for High-Power All-Solid-State Lithium Metal Batteries

Solid-state electrolytes (SSEs) are crucial to high-energy-density lithium metal batteries, but they commonly suffer from slow Li⁺ transfer kinetics and low mechanical strength, severely hampering the application for all-solid-state batteries. Here, we develop a two-dimensional (2D) high-entropy lithium-ion conductor, lithium-containing transition-metal phosphorus sulfide, HE-Li_xMPS₃ (Li_x(Fe_1/5Co_1/5Ni_1/5Mn_1/5Zn_1/5)PS₃) with five transition-metal atoms and lithium ions (Li⁺) dispersed into [P₂S₆]^2- framework layers, exhibiting high lattice distortions and a large amount of cation vacancies. Such unique features enable to efficiently accelerate the migration of Li⁺ in 2D [P₂S₆]^2- interlamination, delivering a high ionic conductivity of 5 × 10^-4 S cm^-1 at room temperature. Moreover, the HE-Li_xMPS₃ laminate can be employed as a building block to construct an ultrathin SSE film (∼10 μm) based on strong C-S bonding between HE-Li_xMPS₃ and nitrile-butadiene rubber. The SSE film delivers a strong mechanical robustness (6.0 MPa, 310% elongation) and a high ionic conductivity of 4 × 10^-4 S cm^-1, showing a long cycle stability of 800 h in lithium symmetric cells. Coupled with LiFePO₄ cathode and lithium anode, the all-solid-state battery presents a high Coulombic efficiency of 99.8% within 2000 cycles at 5.0 C.