Highly enhanced reversibility of a Zn anode by in-situ texturing

The propensity to form irregular and nonplanar Zn electrodeposits during repeated stripping/plating cycles is a main cause of the short lifetime of secondary Zn metal batteries, drawing the focus on strategies allowing for the homogenous growth of Zn over cycling. Here, we report on a highly reversible Zn chemistry in which a typical zinc sulfate electrolyte with added phosphoric acid ensures the (002) epitaxial growth on the (002)-textured Zn foil for a long term (> 1500 h, 1500 cycles). Moreover, the phosphoric acid additive assists in the formation of a Zn2+-conducting solid-electrolyte interphase, further improving the reversibility of the negative Zn electrode. As a result, the coulombic efficiency of a Zn||Ti asymmetric cell within 500 cycles is 96.7% on average. The highly reversible Zn chemistry significantly improves the rate capability and cycling stability of Zn||MnO2 cells. More importantly, a Zn||O2 cell can be cycled for 50 h at a high depth of discharge of the zinc anode (10–20%). The simple but effective texturing agent makes aqueous Zn metal batteries competitive for practical applications.