Hydrogen-Deficient Chain-Like Molecular Structure Confined Hydride Electrolyte for High-Voltage All-Solid-State Lithium Metal Batteries.

The practical application of LiBH in all-solid-state Li metal batteries (ASSLMBs) is hindered by low Li-ion conductivity at room temperature, poor oxidative stability, and severe dendrite growth. Herein, porous [LiNBH] with a hydrogen-deficient chain-like molecular structure are designed for in situ space-confining LiBH, which enables strong attraction of negatively charged H atoms of [BH] anions by Li of [LiNBH] chains that weakens Coulombic interaction between Li and [BH] anions and hence promotes Li ion diffusion. Additionally, the electron-withdrawing effect of [LiNBH] chains induces the local electron localization of LiBH that enhances oxidative stability of LiBH. Therefore, the Li ion conductivity of LiBH reaches 2.2 × 10 S cm at 30 °C, nearly 4 orders of magnitude higher than that of LiBH, with a voltage window of 5 V. Moreover, the interaction between Li metal and [LiNBH] chains results in in situ formation of ultrathin layer composed of LiN and LiB alloys that hinders Li dendrites growth, leading to a critical current density value of 7.5 mA cm and a cycling life of 100 h at 4 mA cm with an overpotential of 125 mV. Hence, LiCoO|LiBH-70LiNBH|Li cell at 0.5 C deliver a high capacity of 89.5 mA h g after 400 cycles.