Suppressing Hydrogen Evolution and Dendrite Formation on a Zn Anode by Coating In₂O₃ with Tailored Affinity to H* and...

To suppress the hydrogen evolution reaction (HER) and dendrite formation on the Zn anode in aqueous Zn-ion batteries, a submicrometer In₂O₃ coating on the Zn anode (referred to as Zn@In₂O₃) was constructed via magnetron sputtering. Density functional theory (DFT) and experimental data show that the In₂O₃ coating suppresses the HER because of its weaker interactions with H* compared with Zn, inhibiting the Volmer step. At the same time, the In₂O₃ coating exhibits a moderate affinity for Zn*, higher than that on Zn but lower than that at the In₂O₃-Zn interface, thus facilitating the desolvation of the hydrated Zn²⁺ ions while promoting its deposition on the Zn substrate beneath the In₂O₃ coating. The resultant suppression of side reactions and dendrite growth significantly enhance the reversible plating/stripping of Zn. The optimized Zn@In₂O₃ stably cycles over 6400 h with a low voltage hysteresis of 9.5 mV at 1 mA cm^-2 and 1 mAh cm^-2 in symmetric cells. The average Coulombic efficiency of Zn plating/stripping is increased from 95.8 to 99.6% owing to the In₂O₃ coating. Moreover, when coupled with the Mn_0.15V₂O₅·nH₂O cathode, the Zn@In₂O₃ battery maintains a capacity retention of 78.6% after 2000 cycles at 5 A g^-1. This facile and economical modification of Zn anodes provides an idea for realizing the practical application of AZIBs.