Interfacial Adsorption Engineering Enables a Highly Utilized Zinc Anode With 99.9% Coulombic Efficiency

ABSTRACT Zinc metal is an appealing anode for aqueous batteries; however, the unsatisfactory reversibility always requires excess zinc for stability compensation, constraining the practical energy density of full cells. Herein, we show Cu interface can be tuned with superior adsorption to address the reversibility challenge by simultaneously improving zincophilicity and suppressing the hydrogen evolution reaction (HER). By engineering an amorphous Cu interface and modifying it with newly formed Cu clusters, the resulting smooth and amorphous Cu surface exhibits strengthened adsorption toward Zn atoms and H intermediates, which originates from an up‐shifted d‐band center. The adjustment of electronic structure favors Zn nucleation and growth while elevates the desorption barrier for continuous HER. As a result, the modified Cu substrate achieves high Coulombic efficiencies (CEs) over 99.9% at practical parameters of 1 mA cm −2 /1 mAh cm −2 (33.3% zinc reaction ratio (ZRR)) and 2 mA cm −2 /2 mAh cm −2 (66.7% ZRR) for 2540 and 1770 h, respectively. Moreover, full cells using this Cu substrate can stably operate for over 250 cycles with a high zinc utilization ratio (ZUR) of 83.3%, achieving a superior energy density of 188.3 Wh kg −1 when compared with commercial aqueous batteries.