A Fully Aqueous Hybrid Electrolyte Rechargeable Battery with High Voltage and High Energy Density

Aqueous rechargeable batteries (ARBs) offer advantages in terms of safety, environmental friendliness and cost over their non-aqueous counterparts. However, the narrow electrochemical stability window of water inherently limits the output voltage and energy density of ARBs. Here, a system with an aqueous hybrid electrolyte containing a Zn anode in alkaline solution and LiMn 2 O 4 cathode in neutral solution is reported. Combining the separated electrode-electrolyte with a Li + -conducting membrane, the potential window is effectively widened to enable an aqueous hybrid electrolyte rechargeable battery (AHERB) above 2.3 V. This battery system delivers a steady energy density of 208 Wh kg −1 (based on the total weight of active materials) at 1.69 C with a high average output voltage up to 2.31 V, cycled for over 1000 cycles with an average Coulombic efficiency of >98%.