Copolymerization effect on the synthesis of Li₂FeSiO₄/C nanocomposites by chemical solution deposition

抄録

Olivine-structured lithium iron silicate is one of the promising cathodes for the development of high energy lithium ion batteries. This article describes the synthesis of phase-pure mesoporous Li₂FeSiO₄/C nanocomposite particles by a modified sol–gel processing via the alkoxide route. Controlled polymerization of Si alkoxide mediated partial hydrolysis in conjunction with copolymerization of Fe precursors chelated with citric acid minimized the formation of impurity phases and lowered the crystallization temperature. This approach resulted in high-purity, mesoporous Li₂FeSiO₄/C nanoparticles aggregated in the submicrometer range (382 nm on average) and comprising primary nanocrystallites with an average diameter of 20 nm. The residual carbon appears to be coated on Li₂FeSiO₄ particles with an average thickness of about 2 nm and resembles a graphene-like surface layer. The material exhibits stable electrochemical performance with a reversible capacity of about 164.5 mAh·g⁻¹ at a rate of 0.1 C. The good cycling stability is attributed to synergistic effects in our synthesis mechanism that produces in-situ carbon coated Li₂FeSiO₄ nanocomposites.