Adjusting zinc ion de-solvation kinetics via rich electron-donating artificial SEI towards high columbic efficiency and stable Zn metal anode

Aqueous zinc ion batteries (AZIBs) subject to severe sluggish electrodeposition process due to burdensome desolvation of hydrate zinc ion (Zn(H2O)(6)(2+) -> Zn2+) which leads to high overpotential, low utilization of zinc and high interface impedance. Here, an artificial solid electrolyte interphase (SEI) with rich electron-donating functional group (cyano group) is proposed for zinc anode to achieve favorable de-solvation process and deliver stable rechargeable AZIBs. The rich-cyano SEI (rc-SEI) can improve the de-solvation kinetics by formation interaction force between cyano group and water sheath of hydrated ions. The de-solvation activation energy (E-a) of hydrated ions for rc-SEI@Zn is only 41.9 kJ mol(-1), much lower than that of the bare Zn (63.7 kJ mol(-1)). The rc-SEI@Zn electrode realizes an enhanced CE of over 99.65 % within 550 cycles in Zn parallel to Cu battery, a low polarization of less than 50 mV and ultra-long cycle life of over 1000 h in Zn||Zn battery. Moreover, Zn parallel to MnO2 full cell with rc-SEI@Zn anode shows 78.9% capacity retention after 690 cycles at 2C (218.2 mAh g(-1) at 1st cycle and 172.1 mAh g(-1) at 690th cycle).

Automated summary

By introducing an artificial solid electrolyte interphase (SEI) with a rich electron-donating functional group (cyano group), the desolvation process of zinc anode in aqueous zinc ion batteries (AZIBs) can be improved, leading to lower polarization, higher cycling efficiency, and longer cycle life.