Abstract: Lithium iron phosphate powders were prepared by hydrothermal synthesis, and coated using glucose as carbon precursor. The contact angles for calculating surface free energy of LiFePO4 powders with three probe liquids were measured. The surface free energy and its dispersive part and polar part were calculated, based on Young equation and the method suggested by Wu. The relations of surface free energy to conductivity, coating property and specific capacity were studied. The results indicated that with the same conductivity, the dispersive/polar ratio of surface free energies (SE) of the powders had no effect on lowrate discharge capability, whereas had great effect on high rate discharge capability. The higher temperature and longer time of pyrolytic reaction led to an increase of the dispersive/polar ratio, which was beneficial for its adhesion with polyvinylidene fluoride (PVdF) and the enhancement of high rate discharge capability.

Key words: LiFePO4, Surface free energy, Conductivity, Rate capability