Advancing Aqueous Batteries: Harnessing Trivalent Indium for Superior Capacity, Efficiency, and Extended Cycle Life

Trivalent indium is distinguished by its unique three-electron In 3+ /In redox system and has a large capacity of approximately 700 mAh g −1 , similar to that of metallic zinc. In addition, indium has a good redox potential (-0.34 V compared to standard hydrogen electrode) and no dendrite growth during the plating/stripping process, which allows In||Ti asymmetric cells to achieve 99.3% to 99.8% High Coulombic efficiency. Remarkably, its polarization in symmetric cells is only 1 mV, 1 to 2 orders of magnitude superior to reported metals. The effectiveness of trivalent indium extends to full-battery applications. Taking the In-MnO 2 system as an example, the battery voltage reaches about 1.2 V, the capacity reaches about 330 mAh g −1 , and the cycle life is extended to 680 cycles. This study highlights the potential of trivalent indium as an anode material characterized by high capacity, efficiency, low polarization, and extended cycle life, thereby providing a compelling trajectory for the advancement of aqueous battery technology.