Boosting the charge transfer of Li2TiSiO5 using nitrogen-doped carbon nanofibers: towards high-rate, long-life lithium-ion batteries

Abstract

Li₂TiSiO₅ (LTSO) has a theoretical specific capacity of up to 315 mA h g⁻¹ with a suitable working potential (0.28 V vs. Li/Li⁺). However, the electronic structure of Li₂TiSiO₅ is firstly investigated by theoretical calculation based on the first-principles approach, and the results demonstrate that Li₂TiSiO₅ acts as the insulator for transferring electrons. Therefore, the framework with better conductivity is very essential for Li₂TiSiO₅ to enhance the charge transfer kinetics. Nitrogen-doped carbon encapsulated Li₂TiSiO₅ nanofibers (LTSO/NDC nanofibers) are obtained by using carbamide as a nitrogen source through an electrospinning technique. The nitrogen-doped carbon matrix with high electronic conductivity improves the electrochemical properties of LTSO significantly. The diffusion coefficient of lithium ions (D_Li⁺) is greatly improved by manual calculation. The LTSO/NDC nanofiber electrode can deliver 371.7 mA h g⁻¹ at 0.1 A g⁻¹ and 361.1 mA h g⁻¹ at 0.2 A g⁻¹, and also shows a comparable cycle performance which could endure a long cycle over 800 cycles at 0.5 A g⁻¹ almost without capacity decay. Hence, the LTSO/NDC nanofiber anode with a high rate and a long life provides a new direction for the realization of LTSO-based compounds in lithium ion batteries.