Ultrathin Surface Coating Enables Stabilized Zinc Metal Anode

TLDR

Aqueous zinc batteries are attractive for their high theoretical capacity and low potential, but uncontrolled gas evolution limits their cycle life and commercial viability. This work demonstrates that atomic layer deposition of TiO₂ can serve as a protective coating for metallic zinc anodes. The TiO₂ layer suppresses gas generation, maintaining effective electrolyte–anode contact and improving coulombic efficiency. The TiO₂‑coated zinc anode shows markedly reduced corrosion, lower overpotential (72.5 mV at 1 mA cm⁻²), and extended cycling—achieving 85 % capacity retention over 1,000 cycles at 3 mA cm⁻²—highlighting its potential for ultrasafe aqueous zinc metal batteries.

Abstract

Abstract With the rapid development of energy storage devices, aqueous battery with noncombustion properties and instinct safe features has received great attentions and Zn anode is investigated intensively due to its high theoretical capacity (820 mAh g −1 ), and low negative potential (−0.762 V vs SHE). However, the unavoidable gas evolution hinders the cyclability and the application in the commercial field. Herein, the atomic layer deposition of TiO 2 coating is first demonstrated as the protection layer of metallic zinc anode. The corrosion of zinc plate is significantly suppressed, leading to less gas evolution and Zn(OH) 2 byproduct formation. The reduced gas generation on the outer surface of the zinc plate will maintain the effective contact area between the electrolyte and anode and leads to an improved coulombic efficiency. In this way, the Zn anode with 100 ALD cycles TiO 2 protection shows reduced overpotential (72.5 mV) at 1 mA cm −2 for Zn–Zn symmetrical battery and additionally, the protection of TiO 2 extended the Zn–MnO 2 battery cycling performance up to 1000 cycles with the capacity retention of 85% at current density of 3 mA cm −2 . The novel design of atomic layer deposition protected metal zinc anode brings in new opportunities to the realization of the ultrasafe aqueous zinc metal batteries.