A strongly coupled FeS2@TiO2 heterostructure with an island-like structure for high-efficiency lithium storage†

Abstract

Titanium dioxide (TiO₂) has garnered substantial interest as a potential anode material for advanced lithium-ion batteries (LIBs) owing to its superior structural stability, rapid pseudocapacitive kinetics, economic viability, and nontoxicity. Nevertheless, its practical application is significantly curtailed by the limitations in specific capacity and inferior intrinsic electronic conductivity. Although carbonaceous materials can enhance electronic conductivity to a certain extent, the deficiency in lithium storage capacity persists as a critical issue requiring amelioration. Herein, we introduce a unique heterostructure composed of TiO₂ nanobelts and FeS₂ nanoparticles, fabricated through a hydrothermal method, followed by cation exchange and a sulfidation process. For the heterostructure, FeS₂ nanoparticles are in situ anchored on the surface of TiO₂ nanobelts, forming an island-like p–n heterostructure (FeS₂@TiO₂). The incorporation of FeS₂ featuring high specific capacity facilitates the emergence of a built-in electric field at the interface between the two compounds, thereby expediting the charge transport during the lithium storage process. As a consequence, the island-like FeS₂@TiO₂ p–n heterostructure delivers a remarkable reversible capacity of 584.9 mA h g⁻¹ at 1.0 A g⁻¹ after 300 cycles, along with superior rate capability (average capacity of 204.8 mA h g⁻¹ at 10.0 A g⁻¹). Even at 5.0 A g⁻¹, the FeS₂@TiO₂ anode maintains a substantial specific capacity of 251.2 mA h g⁻¹ over 3000 cycles, revealing its outstanding cycling stability. This study suggests that the design strategy coupling TiO₂ with other materials that possess high specific capacity could be broadly applied to enhance its electrochemical performance.