Carbon-coated Li4Ti5O12 nanoparticles with high electrochemical performance as anode material in sodium-ion batteries

Abstract

Sodium-ion batteries have been considered as promising alternatives to the current lithium-ion batteries owing to their low cost and abundant raw material. The major challenge of their practical implementation is the lack of favourable anode material. Spinel Li₄Ti₅O₁₂ has been regarded as a potential anode material for its superior capability of sodium-ion storage and relatively appropriate operating voltage. However, the low intrinsic ionic and electronic conductivity of spinel Li₄Ti₅O₁₂ still remains as its major drawback. Herein, carbon-coated Li₄Ti₅O₁₂ nanoparticles have been synthesized through a solid-state reaction and a chemical vapour deposition method and used as an anode material for sodium-ion battery. The composite structure demonstrates excellent stability and an initial discharge specific capacity of 120.1 mA h g⁻¹, which is maintained at 101.5 mA h g⁻¹ after 500 cycles corresponding to 85% of capacity retention at a current density of 0.1 A g⁻¹. In addition, a full cell was fabricated with carbon-coated Na₃V₂(PO₄)₃ as a positive electrode, which displayed discharge specific capacities of 138.5 mA h g⁻¹ that was maintained at 114.7 mA h g⁻¹ after 50 cycles at a current density of 0.05 A g⁻¹, and the capacity retention was 82.8%. The results indicated that the Li₄Ti₅O₁₂ nanoparticle with a carbon layer shows a promising electrochemical performance as anode materials in sodium-ion batteries.