Kinetic and thermodynamic synergy of organic small molecular additives enables constructed stable zinc anode

Abstract

An organic small molecule additive zinc formate is introduced to construct stable Zn metal interphase by electrochemical kinetic control and thermodynamic adjustment. It partially forms a water-formate concomitant dipole layer at the internal Helmholtz electrical double layers (HEDLs) under the preferential adsorption function of formate on Zn surface, reducing the occurrence of side reactions at phase interface. Meanwhile, free formate in HEDLs regulates the Zn2+ solvation sheath structure to accelerate the de-solvation, transference, and deposition kinetics of Zn2+. Besides, the hydrolysis reaction of zinc formate increases the hydrogen evolution overpotential, inhibiting the thermodynamic tendency of hydrogen evolution. Consequently, it presents stable cycle for more than 2400 h at 5 mA cm−2, as well as an average Coulombic efficiency of 99.8% at 1 A g−1 after 800 cycles in the Zn||VO2 full cell. The interphase engineering strategy zinc anode by organic small molecular brings new possibility towards high-performance aqueous zinc-ion batteries.