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 x MPS 3 (Li x (Fe 1/5 Co 1/5 Ni 1/5 Mn 1/5 Zn 1/5 )PS 3 ) with five transition-metal atoms and lithium ions (Li + ) dispersed into [P 2 S 6 ] 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 [P 2 S 6 ] 2- interlamination, delivering a high ionic conductivity of 5 × 10 -4 S cm -1 at room temperature. Moreover, the HE-Li x MPS 3 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 x MPS 3 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 LiFePO 4 cathode and lithium anode, the all-solid-state battery presents a high Coulombic efficiency of 99.8% within 2000 cycles at 5.0 C.