Influence of Conductive Carbon Content Using a Three-Dimensional Foam-Type Current Collector for Lithium Ion Battery

Abstract

LiFePO4 electrodes using three-dimensional NiCrAl metal foam of different conductive carbon content were prepared. Increasing the carbon black content greatly enhanced the rate performance, with a severe capacity fade shown for lower carbon black content with increases current rate. The electrode with no addition of carbon black showed very poor electrochemical performance, due to the high charge transfer resistance (Rct) and high diffusion limitation of Li-ion. The electrodes of increased carbon black loadings enhanced the kinetic performance and dramatically decreased the Rct, due to the large effective contact area between the conductive carbon material and the LiFePO4 particles. However, lower carbon black loading resulted in much higher areal capacity (mAh cm−2) at 0.2 and 0.5 C, due to increases in the amount of LiFePO4 particles from reducing the carbon black loading. According to the results for 8 mA cm−2, the specific capacity of 15 wt.%-electrode was higher than 10 wt.%-electrode. However, electrode polarization of 15 wt.%-electrode was more high than for 10 wt.%-electrode, due to high over-potential by the high current rate. That is to say the optimal conductive carbon content differs according to the intended use.