Carbon Nanofibers as Conductive Additive in LiFePO4 Cathode Material for Li-ion Batteries*

Olivine LiFePO4 is one of the leading candidates for Li-ion batteries cathode materials because of its stable structure, nontoxicity, and relatively low cost. However, LiFePO4 has poor electronic conductivity and slow Li-ion diffusion rate. Different approaches have been established to address this problem. In this work, we address the problem of poor electronic conductivity by incorporating carbon nanofibers (CNFs) into the LiFePO4 cathode as conductive additives. CNFs have a high aspect ratio and excellent electronic conductivity via its reactive inner and outer surface structure. The effect of adding different weight percentages of CNFs to the LiFePO4 cathode was investigated by scanning electron microscope (SEM), four-point probe, and electrochemical measurements. Practically, the composite cathode with 5 wt.% CNFs showed enhanced electrochemical properties in terms of the rate performance, cycling capacity, and capacity retention. The improved electrochemical performance is attributed to the better electronic percolation networks that were created by adding CNFs.