| Secondary zinc ion batteries have received extensive attention because of their high volume specific capacity(5855 Ah L-1)and high safety.In recent years,research on zinc ion batteries has made tremendous progress.However,the problem of low zinc plating/stripping efficiency caused by the growth of zinc dendrites in the cycling process needs to be resolved;in addition,the problems of gas production,parasitic reactions and poor long-term stability faced by aqueous zinc electrolytes are not conducive to its wide application and commercialization.The interface modification of the solid electrolyte interphase(SEI)is expected to be a good solution to the problems associated with Zn anodes.However,due to the relatively high oxidation-reduction potential of Zn,such complex strategies are rarely considered for Zn anodes.To solve this problem,we successfully constructed a ZnF2-rich and ionically permeable composite SEI layer on the surface of the Zn anode by flexible use of the solvated sheath regulation strategy.The main results are as follows:1.A new acetamide/Zn(TFSI)2 eutectic electrolyte was prepared.The combination of experiments and theoretical simulations shows that "zinc complex containing anions"is obtained inside the electrolyte by regulating the coordination environment of TFSI-anion,which effectively reduces the decomposition energy of TFSI-anion.Thus,it is possible to induce the generation of SEI by reducing TFSI-before zinc plating.The protected Zn enables dendrite-free Zn plating/stripping even cycled at a high areal capacity of 5 mAh cm-2(10 mA cm-2).This is attributed to the synergy of SEI layer’s fast Zn ionically permeable coupled with high mechanical strength.The as-obtained SEI layer also enables reversible Zn/V2O5 batteries with excellent cycling durability and near 100%Coulombic efficiency at both low(200 mA g-1)and high(600 mA g-1)rates.2.Transplanting the SEI-coated Zn anode into the aqueous electrolyte to assist the aqueous Zn protection.Once the SEI layer is formed,the SEI-coated Zn anode can be functionalized by favorable Zn2+ transport with low-diffusion barrier(49.7 kJ mol-1),which can facilitate reversible Zn stripping/plating.This protective effect remains significant even if the SEI-coated zinc anode is implanted into a 1 M Zn(TFSI)2 aqueous electrolyte.Therefore,the battery using the SEI-protected Zn anode showed a high capacity retention rate of 97.8%in the self-discharging test. |
