An Economic Bifunctional Electrolyte Additive for Highly Reversible Zinc Anode

Zinc metal batteries (ZMBs) have received a lot of attention due to their high capacity, proper redox potential and low cost. However, zinc anodes suffer from serious dendritic problems and side reactions, resulting in poor cycling stability of zinc ion batteries. Herein, organic additive trimethyl phosphate (TMP) is introduced into inexpensive ZnSO4 electrolyte to stabilize Zn anode. TMP exhibits bifunctional properties in this cost-effective electrolyte system. It prefers adsorbing on (002) plane of zinc which leads to preferential crystal growth and uniform zinc deposition. Moreover, TMP can reshape the original hydrogen bond network, regulate the solvation structure and inhibit the parasitic reaction generated by water. As a result, the zinc anode with TMP addition could maintain 2000 h at a current density of 0.5 mA cm−2 which is superior to bare zinc anode. When paired with V2O5 cathode, the full cell also shows excellent cyclic performance. Such a low-cost bifunctional additive would offer a strategy for stabilizing Zn plating/stripping behaviors and suppressing side reactions in mild aqueous electrolyte.