Electronic Reconstruction via Low‐Degree Fluorination for High‐Performance Zinc‐Ion Battery

Abstract The development of transition metal oxide cathodes with high capacity and ultralong lifespan is one of the keys to promoting the performance of aqueous zinc–ion batteries, but it remains a crucial challenge. Herein, cobalt oxide is applied as an example to demonstrate that low‐degree fluorination is a novel approach to synergistically boost charge storage kinetics and stability. Specifically, partial substitution of O 2− with F − intensifies electron delocalization of Co 3 d orbitals, which reduces bulk charge transfer impedance and endows surface active sites with higher reactivity, thus achieving boosted redox kinetics and energy density. Moreover, the modification of coordination structure with the highest‐electronegativity F − can effectively inhibit irreversible phase transition and structural deformation, which assures significantly optimized cycling stability. As a result, the fluorinated Co 3 O 4 demonstrates a distinctly improved specific capacity of 406 mAh g −1 at 1 A g −1 , approximately a threefold increase compared to one of pristine Co 3 O 4 (131 mAh g −1 ). The assembled fluorinated Co 3 O 4 //Zn battery delivers an ultrahigh energy density of 658 Wh kg −1 at 3.5 kW kg −1 and 95.7% capacity retention after 10 000 cycles. This work offers a new understanding of the electronic engineering of metal oxides toward high‐performance energy storage applications.