Achieving Planar Zn Electroplating in Aqueous Zinc Batteries with Cathode-Compatible Current Densities by Cycling Under Pressure

The advancement of aqueous zinc-ion rechargeable batteries is limited by the degradation of the Zn metal anode during repeated cycling [1,2]. While increasing the current density mitigates anode degradation, this approach leads to capacity decay in Zn-host cathodes, making it unsuitable for full cells. A strategy that enhances anode performance at cathode-compatible current densities is necessary. In this study, we demonstrate that reversible planar Zn deposition can be achieved through the application of external pressure, even at moderate areal current densities of 1 to 10 mA cm−2 [3]. Multiscale characterization reveals that cycling under pressure promotes denser, more uniform Zn deposition, similar to that observed at high cycling rates, but with the added benefit of greater resistance to metal detachment during stripping. Pressure-induced morphology changes in the zinc microstructure limit anode degradation by reducing dead Zn formation and corrosion losses. Mechanical analysis indicates that Zn electroplated at lower current densities is particularly responsive to compression, significantly improving cycling performance. Furthermore, the pressure confines Zn growth to the electrode plane, yielding an anode coverage comparable to that achieved at higher rates. These insights lead to substantially enhanced full-cell cycling performance under applied pressure, suggesting that with appropriate design—such as packing cells in stacks within metallic cases—pressure application in practical systems may be feasible.

[1] Li Z, Robertson AW. Battery Energy, 2023, 2(1), 20220029.
[2] Gourley SW, Brown R, Adams BD, Higgins D. Joule, 2023, 7(7), 1415-1436.
[3] Li Z, Yuan Y, Pu SD, Qi R, Ding S, Qin R, Kareer A, Bruce PG, Robertson AW. Adv. Mater. 2024, 36, 2401576.