In situ zinc citrate on the surface of Zn anode improves the performance of aqueous zinc-ion batteries

The application of aqueous zinc-ion batteries (AZIBs) is impeded by interface side reactions and dendrite formation. The hard problems were addressed by selecting a safe and cost-effective high concentration of citric acid for the treatment of Zn foil, leading to formation of zinc citrate (ZC) on the Zn surface. For one thing, the ZC layer avoids direct contact between the metal anode and electrolyte, and inhibits the side reaction at the interface. And the presence of a lower proportion of active (002) crystal face on the c-Zn surface also serves to mitigate side reactions induced by water. The c-Zn anode has low corrosion current density (4.5 mA cm−2). For another, the ZC layer regulate the electric field on the surface of c-Zn, thereby promote the uniform plating/stripping of zinc. Conclusively, the cyclic life of c-Zn//c-Zn battery is 650 h at 0.8 mA cm−2. The c-Zn//Na-doped V2O5 full battery has a specific capacity of 235.5 mAh g−1 after 200 cycles at 1 A g−1, and a capacity retention rate of 90.2 %. The present work introduces a novel and efficient approach for the surface optimization of zinc metal anodes.