Synthesis and Characterization of Urchin-like NiCo ₂ O ₄ @TiO ₂ Microspheres as High-Performance Anodes for Lithium-Ion Batteries

Developing high-performance anode materials for lithium-ion batteries (LIBs) is critical to meet the growing demand for advanced energy storage systems. In this work, we synthesized an urchin-like NiCo 2 O 4 @TiO 2 core–shell heterostructure via a facile two-step solvothermal–hydrolysis route. Anatase TiO 2 was coated onto spinel NiCo 2 O 4 microspheres. This hierarchical architecture not only preserves the high surface area of the urchin-like template but also establishes robust interfacial contact. Compared with pristine NiCo 2 O 4, the NiCo 2 O 4 @TiO 2 electrode delivers a markedly higher reversible capacity and enhanced cycling stability, achieving a first-discharge capacity of 1210.4 mAh g –1 and retaining 669.6 mAh g –1 after 500 cycles at a current density of 2 A g –1 . Electrochemical impedance analysis further confirms that the TiO 2 coating effectively reduces interfacial resistance: the composite exhibits an ohmic resistance ( R s ) of 2.96 Ω and a charge-transfer resistance ( R ct ) of 186.16 Ω. To elucidate the underlying mechanism of the enhanced electrochemical peformance of the NiCo 2 O 4 /TiO 2 heterointerface, a series of interface models based on transmission electron microscopy (TEM) observations were systematically investigated by density functional theory (DFT). The calculations show that heterointerface formation enhances electronic conductivity and creates energetically favorable Li + storage sites. Li + preferentially inserts into the TiO 2 region or accumulates at the interface, accompanied by significant charge redistribution. The combined experimental and theoretical results demonstrate that interfacial engineering effectively improves electronic transport, structural stability, and Li + storage behavior, providing a promising strategy for designing high-performance transition-metal-oxide anodes for LIBs.