Molecular crowding electrolytes for stabilizing Zn metal anode in rechargeable aqueous batteries

A solid electrolyte interphase（SEI） with a robust mechanical property and a high ionic conductivity is imperative for high-performance zinc metal batteries.However,it is difficult to form such a SEI directly from an electrolyte.In this work,a molecular crowding effect is based on the introduction of Zn（OTF）2 and Zn（ClO4）2 to 2 mol/L ZnSO4 electrolytes.Simulations and experiments indicate that the Zn（OTF）2 and Zn（ClO4）2 not only create a molecularly crowded electrolyte environment to promote the interaction of Zn2+and OTF-,but also participate in the reduction to construct a robust and high ionic-conductive SEI,thus promoting metal zinc deposition to the（002） crystal surface.With this molecular crowding electrolyte,a high current density of 1 mA/cm2 can be obtained by assembling symmetric batteries with Zn as the anode for over 1000 h.And in a temperature environment of -10℃,a current density of 1 mA/cm2 can be obtained by assembling symmetric batteries with Zn for over 200 h.Zn//Bi2S3/VS4@C cells achieve a CE rate of up to 99.81% over 1000 cycles.Hence,the utilization of a molecular crowding electrolyte is deemed a highly effective approach to fabricating a sophisticated SEI for a zinc anode.