Ultrafine Fe₂VO₄ nanoparticles anchored on Ti₃C₂T_x nanosheets (Fe₂VO₄@Ti₃C₂T_x) as high-energy anode for lithium-ion storage

Recently, as a new breakthrough for lithium-ion storage anode materials, transition metal vanadates, such as Fe₂VO₄, have attracted much attention, which, however, still suffer from slow electrochemical kinetics and substantial volume expansion. Hybrid with high conductivity materials is an effective route to deal with these issues. Herein, in situ synthesis of Fe₂VO₄@Ti₃C₂T_x composites with porous sandwich structure by co-precipitation-calcination process was reported. Ultrafine Fe₂VO₄ nanoparticles (10–15 nm) in situ grew and was anchored on Ti₃C₂T_x nanosheets, which effectively inhibits both the grain growth for Fe₂VO₄ and stacking for Ti₃C₂T_x, thus facilitating the electrochemical kinetics and alleviating the volume change of Fe₂VO₄ to maintain the integrated structure during the cycling process. As a result, Fe₂VO₄@Ti₃C₂T_x anode shows high Li⁺ diffusion coefficient (2.72 × 10⁻¹¹ cm² s⁻¹) and pseudocapacitive charge storage mechanism (capacitive charge storage contribution 70.85–84.80 % at 0.2–1.0 mV s⁻¹), which guarantee rapid charging and discharging capability. Consequently, outstanding rate performance (1012–595 mAh g⁻¹ at 0.2–3.0 A g⁻¹) and superior cycling capability (663 and 416 mAh g⁻¹ at 1.0 A g⁻¹ for 200 cycles and 2.0 A g⁻¹ for 500 cycles, with the average capacity attrition rate of 0.059 % and 0.053 %, respectively), were achieved, which render Fe₂VO₄@Ti₃C₂T_x composites important potential for lithium-ion storage.