Synthesis of a new cathode material and its characterization using MAS NMR for lithium ion batteries

Abstract

Unlike a primary battery, a secondary battery can be charged and discharged. Thus, it has attracted a great deal of attention in terms of environmental and economic efficiency. Among a secondary battery, Lithium ion battery has lightweight, high power density and high reactivity. Therefore, the aim of this study is to improve the electrochemical performance by studying the cathode of the lithium ion battery. The structural properties of the cathode were characterized by MAS NMR. Li3V2(PO4)3/C is one of the olivine structure material, has excellent structural stability, reversibility and high specific capacity of 197 mAh g-1. However, Li3V2(PO4)3/C has the low electronic conductivity (2 × 10-8 S cm-1) to limit the wide application. To overcome this problem, we have studied the fully substitution using borate. We demonstrate the electrochemical performances of a highly porous Li3V2(BO3)3/C, synthesized via combustion process as a new cathode material. It has a wide range voltage operability ranged from 0.9 to 4.5 V, which deliver exceptionally high discharge capacity of 257 mAh g-1 at 0.05 C, 95.6% of its theoretical capacity. The present study will for the novel poly-anion compound of Li3M2(BO3)3/C (M=Al, V, Cr, Fe, Ni and Ga) based on triangular (BO3)3- unit which is the lightest poly-anion group, could enhance both the theoretical capacity and energy density, also made low lattice volume change during lithiation/delithiation processes. These materials will be promising cathode materials that meet stringent requirements such as high theoretical capacity, wide voltage operability, low cost, safety and environmental friendliness for the application to electric vehicles (EVs).