Regulating the MXene-Zinc Interfacial Structure toward a Highly Revisable Metal Anode of Zinc-Air Batteries.

Rechargeable aqueous Zn-air batteries have been regarded as one of the most promising systems for flexible energy storage devices due to their high specific energy, safety, and cost effectiveness. However, Zn metal anodes exposed to strong alkaline electrolytes suffer from several issues such as corrosion, dissolution, and passivation, resulting in extremely poor cycle reversibility. Motivated by this challenge, we herein strategically design an MXene/Zn metal anode interfacial structure with single/few-layer TiCT MXene as a protective layer. Such a design not only isolates the direct contact between Zn metal anodes and electrolytes but also inhibits zincate dissolution due to the ion screening function of TiCT, potentially addressing the stubborn issues that Zn anodes faced with. As a result, the TiCT-protected Zn metal anode exhibits superior cycle stability (stable for more than 400 cycles) to the bare Zn counterpart (20 cycles) at a high current density of 5.0 mA cm. When integrated into Zn-air coin cells, it has a high depth of discharge of 91% and operates stably for 140 cycles with small resistance. More interestingly, the excellent flexibility of the as-designed TiCT-protected Zn metal anode endows the quasi-solid-state batteries with admirable voltage stability at different bending angles from 0 to 180°.