A dual-functional circular organic small molecule for dendrite-free zinc metal batteries with long-term cycling

Aqueous zinc (Zn) metal batteries have received widespread attention for their high safety and low cost, but some problems during cycling such as dendrite growth, hydrogen evolution reaction, and corrosion reaction hinder their application. Herein, the organic small molecule 1.4.7.10-tetraazacyclododecane (cyclen) is introduced as an effective additive in zinc sulfate electrolyte. Due to abundant N and cyclic structure, cyclen not only has stronger coordination than H2O molecules, resulting in the changed solvation structure of Zn2+, but also preferentially adsorbs onto the Zn (002) plane, inducing uniform deposition of Zn2+. Therefore, the Zn||Zn symmetrical cell achieved long-term cycling of over 2400 h at 1 mA cm-2 and 1 mAh cm-2. Moreover, the performance of Zn||V2O5 full cell was improved by the addition of cyclen, with a capacity retention rate of 90.9 % after 2000 cycles under 3 A g-1.