The Comparison of Carbon Conductive Additives with Different Dimensions on the Electrochemical Performance of LiFePO4 Cathode

Carbon black, multi-walled carbon nanotubes and graphene nanosheets were respectively added to LiFePO4 particles as conductive additives to investigate the influence on the electrochemical performance. The specific surface area and pore size distribution of LiFePO4 particles were measured by N2 absorption. The microstructure of carbon conductors and LiFePO4 sample were characterized by X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy, respectively. The results of electrochemical measurements indicated that LiFePO4 mixed with graphene nanosheets exhibited the best electrochemical performance, of which the specific capacity was up to 146 mAh g-1 at 0.1 C and 125 mAh g-1 at 1 C. Graphene nanosheets showed plane-to-point electric contact with LiFePO4 particles, owing to the unique two-dimensional planar structure. In this work, it was demonstrated that graphene nanosheets will be the most promising carbon conductive additives in cathode materials for lithium-ion batteries.