Interface coupling in FeOOH/MXene heterojunction for highly reversible lithium-ion storage

Recently, MXene coupling with active nanomaterials show considerable potential for energy storage applications. However, the complicated fabrication of MXene-based composites and their low Li⁺ storage reversibility impede the further application for lithium-ion batteries. Herein, as a proof of concept, a novel architecture of β-FeOOH quantum dots grafted on Ti₃C₂ flakes has been realized via a one-step facile immersion method. The crumple Ti₃C₂ MXene in the synthetic hybrids functions as a favorable matrix to load FeOOH dots due to its open framework, superior electrical conductivity, and low energy barrier of Li⁺ diffusion. In virtue of the strong interfacial interactions of the formed heterojunctions between alkali-Ti₃C₂ matrix and FeOOH, the hybrid enables the enhanced kinetics of charge transfer and stable interfacial structure. Consequently, the FeOOH@3D-MX electrode exhibits superior high-rate capability (286.1 mAh g⁻¹ at 10 A g⁻¹) and particularly durable lithium-ion storage with no capacity decay over 500 cycles (572.3 mAh g⁻¹ after 500 cycles at 500 mA g⁻¹). The enhanced Li⁺ storage mechanism of FeOOH/MXene heterostructures is also evidenced by density functional theory calculations and kinetics analyses. This work exploits a facile strategy to build high-performance anode composite and paves the way to exploring their energy storage mechanisms.