石墨化针状焦的粉碎及储锂性能研究

Crushing Process and Lithium Storage Properties of Graphited Needle Coke

以石墨化针状焦为原料,研究了粉碎方式和沥青包覆对石墨化针状焦形貌、振实密度和储锂性能的影响规律和机理。结果表明,石墨化针状焦经过气流粉碎后呈破碎状,而经过机械涡旋粉碎后呈球形或椭球形,且表面光滑。随着机械涡旋粉碎次数的增加,颗粒粒径D50逐渐减小,振实密度ρ先增加后减小;当粉碎3次时D50为16.2μm,ρ达到最大值0.909 g/cm3。沥青包覆形成的核壳结构可以显著改善石墨化针状焦的电化学性能,包覆后的石墨化针状焦首次放电容量和充放电效率分别323 mA.h/g和89.5%,经过50次循环后的容量保持率达88.2%。

The mechanism and influence of crushing way and asphalt coating on the morphology, tap density and lithium storage properties of graphited needle coke was investigated. The results show that the graphited needle coke crushed by flow appears fragmentized and that crushed by mechanical vortex appears spherical, or ellipsoidal with smooth surface. With the crushing number of mechanical vortex increasing, the particle size DS0 decreases, tap density p increases first and then decreases. The value of DS0 equals to 16.2 tun and p reaches its maximum, 0.909 g/cm3, after crushing three times. The formation of core-shell structure of graphited needle coke coated by asphalt can improve its electrochemical properties, the initial discharge capacity and charge-discharge efficiency are 323 mA.h/g and 89.5%, respectively, the capacity retention reaches 88.2% after 50 cycles.