焦原料种类对人造石墨快充性能的影响

Effect of coke raw materials on fast charging performance of artificial graphite

选取三种不同的焦原料并将其制备成人造石墨材料,通过偏光显微镜、X射线衍射分析仪、倍率充电、电化学交流阻抗谱等方法对材料结构和电化学性能进行表征分析。研究结果表明:由纤维和镶嵌结构组成的针状焦A所得人造石墨的取向性较好,且其极片内Li^(+)扩散较快,在3 C下充电的容量保持率最高,达到81.7%;由镶嵌结构组成的石油焦B所得人造石墨的取向性虽好,但其极片内Li^(+)扩散缓慢;而由纤维结构组成的针状焦C所得人造石墨的取向性最差,同时其极片内Li^(+)扩散较慢;B和C所得人造石墨材料的快充性能均较差。

Three different coke raw materials were selected and prepared into artificial graphite materials.The structure and electrochemical performances of the graphite materials were characterized by polarizing microscope,X-ray diffraction analyzer,rate charging and electrochemical impedance spectroscopy.The results show that the artificial graphite obtained from needle coke which is composed of fiber and mosaic structures has good orientation and rapid Li^(+)diffusion in its electrode.It has the highest capacity retention rate at 3 C,up to 81.7%.Although the orientation of artificial graphite obtained from petroleum coke B which is composed of mosaic structure is good,the diffusion of Li^(+)in the electrode is slow.The orientation of artificial graphite obtained from needle coke C which is composed of fiber structure is the worst,and the diffusion of Li^(+)in the electrode is slow.Therefore,the fast charging performance of artificial graphite materials obtained from B and C are poor.