High Power and Energy Density Aqueous Proton Battery Operated at-90 °C

Freezing electrolyte and sluggish ionic migration kinetics limited the low-temperature performance of rechargeable batteries. Here, an aqueous proton battery is developed, which achieves both high power density and energy density at the ultralow temperature conditions. Electrolyte including 2 m HBF4 + 2 m Mn(BF4)(2) is used for the ultralow freezing point of below -160 degrees C and high ionic conductivity of 0.21 mS cm(-1) at -70 degrees C. Spectroscopic and nuclear magnetic resonance analysis demonstrate the introduction of BF4- anions efficiently break the hydrogen-bond networks of original water molecules, resulting in ultralow freezing point. Based on H+ uptake/removal reaction in alloxazine (ALO) anode and MnO2/Mn2+ conversion in carbon felt cathode, the aqueous proton battery can operate regularly even at -90 degrees C and obtain a high specific discharge capacity of 85 mA h g(-1). Benefiting from the rapid diffusion of proton and the pseudocapacitive character of ALO electrolyte, this battery shows a high specific energy density of 110 Wh kg(-1) at a specific power density of 1650 W kg(-1) at -60 degrees C. This work presents a new way of developing low-temperature batteries.