One-Pot Synthesis of Heterointerface-Engineered TiO2/C Nanospheres with NiSe2/FeSe2 Modifications for Kinetics-Enhanced Sodium-Ion Batteries

Abstract

Despite the fact that titanium dioxide (TiO₂) is a promising anode material for sodium-ion batteries towing to its optimal working potential and exceptional structural stability, its widespread adoption is challenged by its intrinsically low electronic/ionic conductivity and modest theoretical capacity. To address these limitations, we develop a one-pot solvothermal-selenisation strategy to fabricate heterointerface-engineered TiO₂/C nanospheres with NiSe₂/FeSe₂ modifications (NFSe@TO/C). The novelty of this work lies in the multi-synergistic design: the carbon matrix not only effectively mitigates volume variations but also significantly enhances charge transfer kinetics; meanwhile, the in-situ constructed NiSe₂/FeSe₂ heterointerfaces and introduced oxygen vacancies enable a dual Na⁺ storage mechanism dominated by surface-capacitive behaviour. Consequently, the optimized NFSe@TO/C-0.1 anode delivers a high reversible capacity of 391.7 mAh g⁻¹ at 0.1 A g⁻¹, which is higher than that of the pristine Se@TO/C control sample. It also exhibits exceptional long-term cycling stability with 78.9% capacity retention after 80 cycles at 0.1 A g⁻¹ (and 234.4 mAh g⁻¹ after 500 cycles at 0.5 A g⁻¹). This study proposes a universal design strategy integrating defect engineering, heterointerface modulation, and nanoconfinement synergy, offering new perspectives for developing advanced energy storage materials.