Herein, we report the possibility of electrochemical Al³⁺ ion insertion in LiMn₂O₄ in aqueous electrolytes. LiMn₂O₄ exhibits a discharge potential plateau of 1.5 V and a discharge capacity of 65 mA h g⁻¹ is achieved at a current rate of 800 mA g⁻¹ at the 75th cycle with the pre-addition of low-valence Mn ions in an aqueous AlCl₃ electrolyte.