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

Abstract

AbstractThe 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 O2− with F− intensifies electron delocalization of Co 3d 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 Co3O4 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 Co3O4 (131 mAh g−1). The assembled fluorinated Co3O4//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.