Electrochemical Precipitation Energy-Assisted Aqueous Battery with High Voltage and High Electrode Utilization

Increasing battery voltage and electrode utilization is of great significance for improving the energy density of aqueous battery. Herein, for the first time, this work introduces an integrated design strategy to regulate electrode potential and improve electrode utilization based on the concept of electrochemical precipitation energy. By coupling precipitation reaction with original electrode reaction, the Gibbs free energy change (${\Delta }_r{G}^{\theta }$) of the precipitation reaction is coupled to battery reaction's ${\Delta }_r{G}^{\theta }$, thereby altering battery's voltage. Besides, the electrode reaction changes to solid-to-solid reaction after coupling with precipitation reaction, which can improve electrode utilization. The potential of Cu is reduced from 0.34 to −0.96 V (the lowest value among all the reported Cu anode) with a Cu utilization of 87.93% (without additional copper in electrolyte) by coupling Cu₂S's precipitation reaction. Furthermore, the potential of I₂ is increased from 0.54 to 0.65 V (I₂/CuI) and 0.73 V (I₂/PbI₂) by coupling precipitation reaction of CuI and PbI₂ and the shutting effect of I₃⁻ is also limited. As proof of concept, a full Cu₂S battery (cathode: S/Cu₂S, anode: Cu/Cu₂S) is designed with average discharge voltage of 1.12 V, which is the highest value among all the Cu-based aqueous batteries. Due to the certain universality of this strategy, this work provides a new path to regulate the electrode reaction potential and improve electrode utilization.