Long cycle life hybrid lithium‐air batteries based on a weakly acidic lithium iodide catholyte

Summary Hybrid lithium‐air batteries (HLABs), which exhibit outstanding specific energy and low overpotential, have been examined by many researchers. However, serious problems including capacity fading and poor stability of solid electrolyte membranes have been encountered and may be insufficient to meet the high demands of future development. Herein, the objective of this study was to propose a novel weakly acidic electrolyte for enhancing the battery cycle life while strictly ensuring stability during the charging and discharging processes. Studies have shown that the cathode electrolyte pH significantly affects the stability of Li1−xAlxGe2−x(PO4)3 (LAGP), which is sintered at high temperature with Li2CO3, Al2O3, GeO2, and NH4H2PO4 powders as precursors. Meanwhile, the electrochemical performance in ambient air (RH = 15%) with the optimized electrolyte showed stability over 525 cycles (2100 hours). Compared with the Coulombic efficiency of HLABs using LiOH catholyte, >20% enhancement is achieved with a discharge‐specific capacity of 10 675 mAh g−1. Inspired by the excellent reversibility of I−/I3− and high solubility of LiI in water, this study proposes a promising method for catholyte selection for LAGP‐based HLABs.