Lead-Free Solid-State Organic-Inorganic Halide Perovskite Electrolyte for Lithium-Ion Conduction

Exploring new solid electrolytes (SEs) for lithium-ion conduction is significant for the development of rechargeable all-solid-state lithium batteries. Here, a lead-free organic-inorganic halide perovskite, MASr_0.8Li_0.4Cl₃ (MA = methylammonium, CH₃NH₃ in formula), is reported as a new SE for Li-ion conduction due to its highly symmetric crystal structure, inherent soft lattice, and good tolerance for composition tunability. Via density functional theory calculations, we demonstrate that the hybrid perovskite framework can allow fast Li-ion migration without the collapse of the crystal structure. The influence of the lithium content in MASr_1-Li₂Cl₃ (x = 0.1, 0.2, 0.3, or 0.4) on Li⁺ migration is systematically investigated. At the lithium content of x = 0.2, the MASr_0.8Li_0.4Cl₃ achieves the room-temperature lithium ionic conductivity of 7.0 × 10^-6 S cm^-1 with a migration energy barrier of ∼0.47 eV. The lithium-tin alloy (Li-Sn) symmetric cell exhibits stable electrochemical lithium plating/stripping for nearly 100 cycles, indicating the alloy anode compatibility of the MASr_0.8Li_0.4Cl₃ SE. This lead-free organic-inorganic halide perovskite SE will open a new avenue for exploring new SEs.