Understanding the Zeta Potential in Regulating Zn Deposition Kinetics for Zn‐Ion Batteries

Abstract

Abstract Severe Zn 2+ concentration polarization at the anode/electrolyte interface induces inhomogeneous electric field distribution on the Zn anode surface in aqueous zinc‐ion batteries (AZIBs), causing dendrite growth and formation of “dead zinc”. Colloidal electrolytes are used to regulate Zn plating/stripping behavior. However, there is a lack of systematic and fundamental understanding of the adsorption capacity of colloidal particles for Zn 2+ and Zeta potential (ZP) in optimizing Zn deposition kinetics. Herein, the ZP of oxide nanoparticles (ONPs, i.e., MgO, SiO 2 , Al 2 O 3 ) and the adsorption energy for Zn 2+ are studied to evaluate their effects on enhancing the cyclic stability of AZIBs. A Gum Arabic (GA) coating strategy on the ONPs surface is executed to eliminate the interference of the surface chemical environment for Zn 2+ adsorption energy. Therefore, the screening principle for ONPs based on ZP is established when they are used in colloidal electrolytes. Specifically, the SiO 2 colloidal electrolyte (4Z‐S) with the ZP of −28.6 mV facilitates rapid Zn deposition kinetics. Accordingly, zinc electrodes in 4Z‐S electrolyte realize a high coulombic efficiency (CE) of 99.7% and long‐term life of 3400 h at 5 mA cm −2 . A 145 mAh Zn||I 2 pouch cell achieves a high capacity retention of 94.8% after 1000 cycles, implying promising practical application.