Reversible proton conversion manipulating charge engineering for highly stable Zn anode

Grievous Zn dendrites and intricate parasitic reactions tremendously hamper the commercialization of Aqueous Zn metal batteries (AZMBs). Herein, the reversible proton conversion mechanism is reported to achieve longterm stable Zn anode by introducing niacin (NAC) additive into electrolyte. The highly responsive NAC can simultaneously assist Zn2+ transport, manipulate interfacial electrodeposition behaviors, and mitigate waterinduced side reactions. Specifically, protonated NAC (NACH+) tendentiously occupy active water sites to construct an electrostatic shield, adaptively modulating charge carriers (H+ and Zn2+) distribution and reduction barrier of Zn2+ to favor dendrite-free Zn (101) deposition. With the deeper cycling, NAC, the deprotonation of NACH+, further coordinates with Zn2+ to guarantee sufficient Zn2+ transport toward electrodeposition interface through phonon exchange with adsorbed NACH+. The as-modified electrolyte enables a remarkable lifespan of over 3900 h and achieves 750 h under deep cycling (10 mA cm-2, 10 mAh cm-2). This work paves a brand-new path toward achieving high-performance AZMBs.