Hydrothermal synthesis and electrochemical performance of nanoparticle Li₂FeSiO₄/C cathode materials for lithium ion batteries

Li₂FeSiO₄ nanoparticles are successfully synthesized via hydrothermal approach, with the hydrothermal process monitored in detail. Structural characterizations by XRD, FTIR, SEM and HRTEM measurements reveal that the Li₂FeSiO₄ nanoparticles have a high crystalline degree and monodisperse nanoparticle shape with a size around of 50-200 nm. To further improve the electronic conductivity, the Li₂FeSiO₄ nanoparticles are coated by a carbon layer using in suit polymerization of dopamine. Moreover, the effect of carbon content for electrochemical performance of Li₂FeSiO₄/C is systemically investigated, and as a result, the composite with a ratio of Li₂FeSiO₄ and dopamine of 3:1 demonstrate the best electrochemical performance with a discharge specific capacity of 148 mA h g^-1 at a rate of 0.1 C at room temperature. Furthermore, the electrochemical performance of Li₂FeSiO₄/C at high temperature of 55 °C is also investigated, and it also exhibits a good performance with a discharge specific capacity of 240 mA h g^-1at a current rate of 0.2 C.