Enhancing interface kinetics in zinc powder anodes via β-cyclodextrin modification toward zinc ion batteries with low N/P ratios

Abstract

The high utilization rate, processability and tunability of zinc powder make it a promising candidate for anodes in rechargeable zinc-ion batteries. However, a rough surface with a high surface area exacerbates corrosion and dendrite growth. Here, β-cyclodextrin (β-CD) was introduced into zinc powder slurry as a multi-functional modifier to optimize the interface and improve the cycling performance of the zinc powder anode through its unique cavity structure. First, β-CD greatly enhances interfacial compatibility with a contact angle of 23.0° through the hydrophilic hydroxyl groups, leading to an extremely low voltage hysteresis of 12 mV. Second, the anion CF₃SO₃⁻ is revealed to be trapped inside the cavity of β-CD, impairing barriers for Zn²⁺ migration and significantly elevating the Zn²⁺ transference number to 0.72. The symmetrical Zn||Zn cell assembled with a β-CD modified zinc anode can achieve stable cycling for 210 h at a high depth of discharge (DOD) of 80%. At a low N/P value of 1.0, the full battery coupled with a ZnVO cathode exhibits a long cycle life of over 280 cycles. It provides a new strategy for the design of a highly stable zinc powder anode.