Electrophoretic Deposition of Additive-Free Zeolitic Imidazolate Framework-67-Derived Cobalt Oxide Anodes for Lithium-Ion Batteries

Abstract

Additive-free electrode architectures are important for clarifying the intrinsic lithium-storage behavior of MOF-derived conversion-type anode materials, because conventional slurry electrodes contain polymer binders and conductive carbon additives that can obscure the electrochemical response of the active material. Herein, zeolitic imidazolate framework-67 (ZIF-67) particles were directly deposited onto Cu foil by direct current electrophoretic deposition and subsequently oxidized in air to fabricate binder- and carbon-free Co3O4 thin-film anodes. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses confirmed that the crystalline ZIF-67 precursor was successfully converted into porous spinel Co3O4 while maintaining a film-type electrode architecture. The resulting electrode exhibited characteristic Co3O4 conversion reactions, including the initial reduction of Co3O4 to metallic Co/Li2O and the reversible oxidation of Co during charging. Despite the absence of conductive additives and binders, the electrode delivered stable charge–discharge behavior and retained approximately 250 mAh g−1 even at 10 C. Moreover, the capacity recovered when the current rate returned to 0.1 C, indicating good structural and electrochemical robustness. These results demonstrate that electrophoretic deposition is a simple and effective strategy for constructing additive-free MOF-derived oxide anodes for high-rate lithium-ion batteries.