Interface engineering for functionalized ultra-thin zinc anodes in aqueous zinc-ion batteries

<h2>Summary</h2> To further enhance the practicality of zinc-ion batteries, attention should be focused not only on prevalent challenges such as side reactions and dendrite growth but also on electrode thinning and the improvement of zinc utilization efficiency. The functionalized ultra-thin zinc anode with a ZnF₂ interlayer addresses concerns and shows high reversibility, and its low-redundant design enables high energy density, potentially narrowing the gap with commercial lithium-ion batteries. Additionally, F plays a significant role in full batteries by promoting the comprehensive reversibility of by-products such as Zn₄SO₄(OH)₆·5H₂O, thereby enabling the ultra-thin Zn anodes to exhibit a long lifespan of 500 h. In full batteries, a capacity of 299 mAh g⁻¹ and an energy density of 319 Wh kg⁻¹ are attained, accompanied by a 92% retention rate at 1 C after 1,000 cycles. These results strongly demonstrate that interface engineering for functionalized ultra-thin Zn anodes represents a promising strategy for aqueous zinc-ion batteries.