Preparation And Electrochemical Properties Of Small-Sized MCMB

Mesophase carbon microbeads (MCMB) is an excellent anode material for lithium ion batteries owing to its good electrolyte adaptability, cycling stability and rate capability. Generally, the particle diameters for manufactured MCMB are in the range of 10-50μm, the electrochemical properties, especially the high-rate performance need to be further improved.This study focused on the preparation of MCMB in small particle size using emulsification-suspension method by controlling the raw material (mesophase pitch, MP) particle size, emulsifier/MP ratio, temperature and soaking time. Then by stabilization, carbonization and graphitization, graphitized MCMB was obtained. SEM, XRD, IR, TG-DSC, laser particle size analysis and optical microscopy were used to test the shape, size distribution and structure of MCMB. The electrochemical performances of MCMB were investigated by charge-discharge cycles, cyclic voltammetry and AC impedance.The results showed that the processing conditions on the MCMB has an important influence:emulsifier/raw materials, mixing rate,temperature and time are important factors for the preparation of MCMB with 1.5μm particle size. While comparing electrochemical properties of MCMB in different sizes, we found that the MCMB with small size has good cycle stability. After 50 cycles, the capacity retention is 98.1%. It shows a good high-rate performance at the current density of 400mA/g, the discharge capacity is 114.7 mAh/g, much higher than that of MCMB in big size. In addition, the study also compared the MCMB in small particle size and the industrial products from Japan. The results show that the former also has better cycling stability and high-rate performance.