In Situ Formed Co(OH)F Enabling Electronic and Atomic‐Level Structure Optimization in Medium‐Entropy Fluoride Cathodes for Zinc Batteries

ABSTRACT

Cobalt‐based cathodes have attracted considerable attention in aqueous zinc batteries, however, their application remains impeded by intrinsic trade‐off between high electrochemical activity and long‐term cycling stability. Herein, an entropy‐regulated fluoride cathode is proposed to overcome the limitations via co‐engineering electronic and atomic structures. Specifically, x‐ray absorption spectroscopy (XAS), x‐ray photoelectron spectroscopy (XPS), and first‐principle calculations collectively demonstrate that Co(OH)F is formed in situ within the fluoride matrix during electrochemical cycling and induces electron reconstruction. Concurrently, the generated Co(OH)F shortens Co─F bond length within the entropy‐regulated fluoride, reinforcing atomic‐level structural integrity and enabling excellent cycling performance. Moreover, a hollow architecture is integrated to homogenize flux and electric field distributions, ensuring sufficient accessibility of active sites while mitigating interfacial degradation. Consequently, the assembled zinc battery exhibits a high specific capacity of 252.3 mAh·g ⁻¹ and superior cycling stability (92.4% capacity retention after 25 000 cycles at 10 A·g ⁻¹ and 90.8% capacity retention after 50 000 cycles at 20 A·g ⁻¹ ). This work demonstrates a synergistic approach that simultaneously achieves high redox activity and structural robustness in cobalt‐based cathodes for zinc batteries.