Targeted Solutions to Improve the Overall Performance of Hydride‐Based All‐Solid‐Batteries

All‐solid‐state lithium batteries using solid electrolytes hold promise for enhancing energy density. However, some electrolytes with high ionic conductivity are declared unusable because they failed to show compatible with the anode, cathode or even worse, both. Herein, it simultaneously introduced doping and interfacial tuning to prepare fast ion conductor LiBH4‐MgO‐MgI2, which can achieve an ionic conductivity of 1.45 × 10−4 S cm−1 at 50 °C. This electrolyte has the usable ionic conductivity near room temperature, but faces the most extreme challenge of instability at both the lithium anode and high‐voltage cathode. Targeted solution strategies is proposed to return this electrolyte to serviceability. The physical isolation and lithium alloy is employed to solve the lithium anode issue, while the bilayer electrolyte design is applied to the high voltage cathode issue. The LiCoO2|Li3InCl6|LiBH4‐MgO‐MgI2|C|Li and LiCoO2|Li3InCl6|LiBH4‐MgO‐MgI2|LiAl, cycled upon 25 cycles at 0.1 C, achieving reversible capacities of 70 and 90 mAh g−1, respectively. With the targeted solutions for ionic conductivity, anode and cathode compatibility, it will pave the way for commercial application for hydride electrolytes.