Influence of the Weight Ratio Between Cathode Conductive and Binder Materials on the Capacity of Li-Ion Batteries

摘要

Electrodes of lithium ion batteries usually consist of active materials, conductive additives and inactive polymeric binder. Carbon black is widely used as conductive material to increase the electric conductivity in electrodes. The function of binders is to provide adhesion between particles of active and conductive materials. It is known that the electric performance of lithium ion batteries primarily depends on active materials. In this study, the contributions of conductive and binder materials to the battery performance are investigated by adjusting the weight ratios of conductive additives and binder material with unchanging weight ratio of active material during blending slurry for the cathode material only. Anode material is not the target to study and consists of lithium metal. The cathode consists of active material as LiMn204, conductive additives as carbon black, and binder as PVDF. The fixed weight percentage of active material is 85 wt %. Five different weight ratios of conductive additives which vary from 1.5 wt % to 13.5 wt % by 3 wt % and binder decreases in the reverse order from 13.5 wt % to 1.5 wt % by 3 wt % to maintain the ratio of 15 wt % total. As the weight ratios of conductive additives increase, the capacity of charge and discharge also increases. However, if the weight ratio of conductive additives is larger than that of binder, there is no improvement in the capacity. The best capacity of 109.26 mAh/g is achieved when the two ratios is the same at 7.5 wt %.