Advancing Aqueous Trivalent Metal Batteries by Realizing Planar Indium Plating with Ultrahigh Efficiency and Long Lifespan

Aqueous trivalent metal batteries represent a compelling candidate for energy storage, due to the intriguing three-electron transfer reaction and distinct properties of trivalent cations. However, little research progress has been achieved with trivalent batteries, due to the inappropriate redox potentials and drastic ion hydrolysis side reactions. Herein, we selected an appealing yet underrepresented trivalent indium as an advanced metal choice, and we revealed the crucial effect of substrate on its plating mechanism. When copper foil is used, an indiumophilic InCu alloy interface can be <i>in-situ</i> formed upon plating, which exhibits favorable binding energies and low diffusion energy barriers for indium atoms. Consequently, a planar, smooth, and dense indium metal layer was uniformly deposited on the copper substrate, leading to outstanding plating efficiency (99.8-99.9%) and exceedingly long lifespan (6.4-7.4 months). The plated indium anode was further paired with high-mass-loading Prussian blue cathode (2 mAh cm^-2), and the full cell (N/P = 2.5) delivered an excellent cycling life of 1000 cycles with 72% retention. This work represents a significant advancement in the development of high-performance trivalent metal batteries.Aqueous trivalent metal batteries represent a compelling candidate for energy storage, due to the intriguing three-electron transfer reaction and distinct properties of trivalent cations. However, little research progress has been achieved with trivalent batteries, due to the inappropriate redox potentials and drastic ion hydrolysis side reactions. Herein, we selected an appealing yet underrepresented trivalent indium as an advanced metal choice, and we revealed the crucial effect of substrate on its plating mechanism. When copper foil is used, an indiumophilic InCu alloy interface can be <i>in-situ</i> formed upon plating, which exhibits favorable binding energies and low diffusion energy barriers for indium atoms. Consequently, a planar, smooth, and dense indium metal layer was uniformly deposited on the copper substrate, leading to outstanding plating efficiency (99.8-99.9%) and exceedingly long lifespan (6.4-7.4 months). The plated indium anode was further paired with high-mass-loading Prussian blue cathode (2 mAh cm^-2), and the full cell (N/P = 2.5) delivered an excellent cycling life of 1000 cycles with 72% retention. This work represents a significant advancement in the development of high-performance trivalent metal batteries.