Abstract:

Li₂MnSiO₄/CNTs composite cathode material for lithium ion batteries was in situ synthesized by the sol-gel process assisted with hydrothermal method. The crystalline structure and morphology of the obtained samples containing 0, 5, 10, 20 and 30 g carbon nanotubes(CNTs) in 1 mol Li₂MnSiO₄, respectively, were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and their electrochemical performances were evaluated by different electrochemical test. The results show that the grains of samples have narrow size distribution and their dimension is about 100 nm. They are easy to be an agglomerate mass and the agglomeration of the samples is gradually reduced with the increase of the contents of CNTs. The XRD patterns reveal that the well-crystallized Li₂MnSiO₄/CNTs materials are orthorhombic with space group Pmn2₁. The sample with 20 g CNTs in 1 mol Li₂MnSiO₄(the carbon content is 16.74%) demonstrates the best electrochemical performance, showing an initial discharge capacity of 150 mA·h/g and a discharge capacity of 80 mA·h/g after 20 cycles at 10 mA/g current density. The in situ composite of CNTs could improve the overall conductivity and the electrochemical performance of Li₂MnSiO₄ cathode materials.

Key words: Lithium ion battery, Cathode material, Li₂MnSiO₄, Carbon nanotubes