Zn anodes of aqueous Zn metal batteries face challenges from dendrite growth and side reactions. Building Zn(002) texture mitigates the issues but does not eradicate them. Zn(002) still faces severe challenges from corrosive electrolytes and dendrite growth, especially after hundreds of cycles. Therefore, it is necessary to have a passivation layer covering Zn(002). Here, Zn(002) texture and surface coating are achieved on Zn foils by an one-step annealing process, as demonstrated by ZnS, ZnSe, ZnF2, Zn3(PO4)2 (ZPO), etc. Using ZPO as a model, the coupling between surface coating and Zn(002) is illustrated in terms of dendrite-suppressing ability and diffusion energy barrier of Zn2+. The modified Zn foils (Zn(002)@ZPO) exhibit the excellent electrochemical performance, far superior to Zn(002) or ZPO alone. In the full cells, the performance is greatly improved even under harsh conditions, i.e., high areal capacity and limited Zn resource. This work achieves crystal engineering and surface coating on Zn anodes simultaneously and discloses the in-depth insights about the synergy of crystal orientation and passivation layers.
Keywords: Zn anodes; Zn(002) texture; aqueous batteries; zinc dendrite; zinc phosphate.