Synthesis And Performance Studies Of Lithium Vanadium Phosphate As Cathode Materials For Lithium-Ion Batteries

Exploring stable and safe cathode materials is an urgent issue to the development of Lithium ion battery. Poly-anion type Li3V2(PO4)3(LVP) have attracted immense research interest for its high ion diffusion coefficient, high work voltage, high theoretical specific capacity and excellent safety.Herein, we report on a new hydrothermal method to synthesize uniform microsoherical LVP/C with glucose as carbon source. Typically, a layer of carbon with the thickness of about 5 nm was coated onto the well crystallized LVP spheres and the size of the core-shell structure distributes between 1-3μm, LVP particles have a size of about 50–100 nm embedded in a carbon matrix, the content of carbon is about 6%. The composite material shows excellent cyclability and rate performance when tested between 3-4.3V. Specific capacity remains 92% after more than 100 cycles at 1C and 10 C. The outstanding electrochemical performance of the material most probably due to the uniformly dispersed microspheres and unique hierarchical structure with nanosized monoclinic LVP embedded in partially graphite carbon with 3D channels for Li+ transportation. The structure keeps intact in the lithium insertion/extraction cycling process, the partially graphite carbon layer improves the electron conductivity of the intrinsically poor LVP and nanosized LVP particles shorten lithium transport distance, and hence the higher charge–discharge rates can be achieved.We have also used industrial raw ammonium poly vanadate grains with certain amounts of impurities to replace analytical pure ammonium metavanadate here. Similar LVP microspheres can also be obtained, and the electrochemical performance is comparable to that of synthesized with analytical pure ammonium metavanadate. It indicates that the facile synthetic method holds great potential in large scale production.