Morphology-Tunable Binary Transition Metal Oxide Heterostructure@Carbon Composites for Lithium-Ion Batteries

Abstract

Heterostructures of binary and unary transition metal oxides (B and UTMOs) have demonstrated excellent electrochemical performance in lithium-ion batteries (LIBs) due to synergistic effects; however, there remains a lack of research combining multiple strategies for synergy enhancement. Herein, we present the development of crystallinity-controlled heterostructures based on nickel and cobalt oxides (NiCo2O4/NiO and NiO/Co3O4) with different morphologies (urchin- and flower-like structures, e.g., U-NiCo2O4/NiO and F-NiCo2O4/NiO) to investigate the influence of heterostructure combinations and morphologies on electrochemical performance in LIBs. The morphologies of the heterostructures were controlled by adjusting the fluoride concentration during the synthesis of the nickel-cobalt (Ni-Co) precursor, while heterostructure combinations were regulated by heat treatment under specific conditions. When used as anodes for LIBs, electrochemical analyses revealed that the carbon-coated urchin-like U-NiCo2O4/NiO (U-NiCo2O4/NiO@C) sample provided more efficient charge transfer and a shorter Li-ion transport pathway compared to its counterpart (F-NiCo2O4/NiO@C) due to its high surface area and distinctive morphological features. In addition, U-NiCo2O4/NiO@C exhibited superior electrochemical performance as an anode in LIBs than U-NiO/Co3O4@C, indicating that the advantageous effects of BTMO over UTMO can effectively enhance LIB performance. This facile synthesis approach provides a foundation for morphology-controlled heterostructures in the development of high-performance anode materials for LIB applications. © 2025 American Chemical Society.