沥青包覆天然石墨作锂离子电池负极材料的研究

INVESTIGATION ON PITCH COATED NATURAL GRAPHITE AS THE CATHODE MATERIAL FOR LI-ION BATTERY

将天然鳞片石墨与煤沥青以7∶3的比例混合研磨,压力成型并粉碎至大约20μm后将其进行炭化得到炭化样品,并取部分炭化样品对其石墨化得到石墨化样品,将得到的炭化、石墨化样品及天然石墨分别进行XRD、SEM测试,并作为锂离子电池负极材料装配电池后进行电化学性能测试。结果表明,经处理后在石墨表面包履了一层沥青,电化学性能提高,炭化后的包覆样品首次效率比石墨提高了10%,但充放电容量偏低,而石墨化后的包覆样品放电容量及首次效率比天然石墨分别提高了16mA h/g和11%,不可逆容量降低了59mA h/g,稳定后放电容量为380mA h/g,效率为99.6%。

Natural flake--like graphite mixed with coal tar pitch at a proportion of 7 ： 3 was treated by grinding,molding and then was shattered to atout 20μm,after that the carbonization and graphitization were carried out. Carbonized sample and graphitized sample and natural graphite are investigated by X--ray diffraction,scanning electron microscopy. Li--ion batteries are assembled with them as the cathode materials and then electrochemical properties are researched. The results show that the natural flake-like graphite is coated by a layer of pitch, the electrochemical properties are improved, the initial efficiency of carbonized sample is higher than natural graphite by 10%,but its capacity of charging and discharging is expected to be higher. The discharging capacity of graphitized sample is higher than natural graphite by 16 mAh/g and its initial efficiency is higher by 11%,its irreversible capacity is lower by 59 mAh/g,after the first cycle tis discharging capacity and effciency are respectively 380 mAh/g and 99. 6%.