通过循环伏安、恒流充放电和扫描电子显微镜等方法,对在1500和2800℃下进行热处理的针状焦炭(NC)的微观结构及作为正极材料的储能特性进行研究,考察了石墨化程度对材料储能性能的影响.2种热处理NC在有机电解液中,当电流密度为50 mA/g时,放电比容量分别为70.1和90.6 mA·h/g;当电流密度为5 A/g时,2种NC的放电比容量为55 mA·h/g左右;而商用活性炭当电流密度为50 mA/g时,比容量只有35.9 mA·h/g.2个NC在1 A/g的电流密度下循环1000次的保持率分别为95.7%和89.2%.
Microstructure and energy storage performance of the needle coke heated at 1500 and 2800 ℃ were investigated by scanning electron micrograph( SEM), cyclic voltammetry(CV) and charge-discharge methods, and the influence of the degree of graphitization to the performance of graphite was studied. The specific discharge capacity of needle coke sintered at 1500 and 2800 ℃ were 70. 1 and 90.6 mA · h/g in organic electrolyte when the current density was controlled at 50 mA/g. The specific capacity was 55 mA · h/g when the current density was raised to 5 A/g. However, the specific capacity of commercialization active carbon was only 35.9 mA · h/g when the current density was controlled at 50 mA/g. The retention of the capacitance after 1000 charge-discharge cycles were 95.7% and 89.2%, respectively, when the current density was controlled at 1 A/g.