Three-in-One Zinc Anodes Created by a Large-scale Two-Step Method Achieving Excellent Long-Term Cyclic Reversibility and Thin Electrode Integrity.

Abstract

Practical aqueous zinc-ion batteries require low-cost thin zinc anodes with long-term reversible stripping/depositing. However, thin zinc anodes encounter more severe issues than thick zinc, such as dendrites and uneven stripping, resulting in subpar performance and limited lifetimes. Here, this work proposes a three-in-one zinc anode obtained by a large-scale two-step method to address the above issues. In a three-in-one zinc anode, the copper foil as an inactive current collector solves the gradual reduction of the active area when only the pure zinc as an active current collector. This work develops an automatic electroplating device that can continuously deposit a zinc layer on a conducting foil to meet the demand for zinc-coated copper foils. The sodium carboxymethylcellulose (CMC)-zinc fluoride (ZnF2) protective layer prevents direct contact between zinc and separator, and provides a uniform and sufficient supply of zinc ions. The CMC-ZnF2-coated copper foil performs up to 3000 reversible zinc deposition/stripping cycles with a cumulative capacity of 6 Ah cm-2 and an average Coulombic efficiency of 99.94%. The Zn||ZnVO cell using the three-in-one anode achieved a high capacity retention of over 70% after 15000 cycles. The proposed three-in-one anode and the automatic electroplating device will facilitate industrialization of practical thin zinc anodes.