Lactic-acid-derived interphase facilitates Zn2+ transfer kinetics and uniform Zn deposition for stable aqueous zinc-ion batteries

Aqueous zinc-ion batteries are promising for stationary energy storage, but the poor reversibility of Zn metal anodes remains a major obstacle. Dendritic Zn growth, hydrogen evolution, and uneven ion flux often occur together at the Zn/electrolyte interface, leading to rapid capacity decay and limited cycle life. Herein, a simple lactic-acid-based liquid treatment is used to reconstruct the Zn surface and obtain a lactic-acid-derived interphase on Zn foil (LA@Zn). The oxygen-containing interphase improves surface wettability and provides polar sites for Zn 2+ interaction, thereby promoting interfacial Zn 2+ transport and helping homogenize ion flux. Meanwhile, it reduces direct Zn–water contact, thereby weakening corrosion and hydrogen evolution. As a result, the LA@Zn symmetric cell operates for over 1500 h at 0.1 mA cm −2 /0.1 mAh cm −2 , and LA@Zn//Cu maintains nearly 100% Coulombic efficiency for 1000 cycles at 5 mA cm −2 /1 mAh cm −2 . When paired with a VO 2 cathode, the LA@Zn//VO 2 full cell retains 80.1% of its initial capacity after 500 cycles at 1 A g −1 and enables stable cycling for 2500 cycles at 10 A g −1 . This work presents a facile surface-reconstruction strategy for stabilizing Zn anodes in aqueous batteries.