A promising composite solid electrolyte of garnet-type LLZTO and succinonitrile in thermal polyurethane matrix for all-solid-state lithium-ion batteries

For solid-state electrolyte in lithium-ion batteries, high crystal boundary impedance leads to tough electrolyte-electrode interfacial issues. Here, we introduce garnet Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) nanoparticles and succinonitrile (SN) into thermal polyurethane (TPU) to fabricate a composite solid-state electrolyte (TPU/LLZTO/SN), achieving high ionic conductivity of 6.452 × 10⁻⁴ S cm⁻¹. The TPU polymer with specific soft and hard segments allows lithium ions fast transport and holds good mechanical strength as the electrolyte matrix. The ionic conductor LLZTO further improves the ionic conductivity and mechanical property of the composite electrolyte membrane. Additional SN supplies the electrolyte’ wide electrochemical stabilization window, and enhances the metallic lithium compatibility of the TPU matrix. As a result, the as prepared TPU/LLZTO/SN electrolyte presents high lithium ions transference number of 0.64, and also good mechanical property.