Kinetics-Matched Electrode Design for Zn-Metal Free Zinc Ion Batteries with High Energy Density and Stabilities

Abstract

The metal-free rocking chair type Zn-ion batteries (ZIBs) provide a promising approach toward the promotion of the Zn-based batteries by circumventing the challenges including dendrite growth, hydrogen evolution reaction (HER), and surface corrosion. In order to sufficiently exploit the available capacity of this metal-free batteries, it is necessary to effectively enhance the sluggish reaction kinetics of divalent zinc ions. Equally important is to achieve a balance in the kinetics between cathode and anode. Here, hetero-valent doping and oxygen vacancy engineering are employed to effectively enhance the reaction dynamics of V₂O₅ cathodes and MoO₃ anodes. Moreover, to the best of the knowledge, for the first time, the strategy of kinetics matching between the two electrodes is applied to the construction of rocking-chair zinc ion batteries, enabling the cathode and anode to share similar zinc ion migration rates, and achieving a high energy density of up to 58.7 Wh kg⁻¹ (based on the total electrode mass) as well as excellent cycling stability (90% after 500 cycles). This work demonstrates the importance of kinetics matching in zinc-ion full-cell performance and pave a benefitable avenue to for the pursuit of advanced multi-valent metal-ion batteries.