The work presented in this report was a detailed comparative study of the electrochemical response exhibited by graphite anodes in Li-ion batteries having different physical features. A comprehensive morphological and physical characterization was carried out for these graphite samples via X-ray diffraction and scanning electron microscopy. Later, the electrochemical performance was analyzed using galvanostatic charge/discharge testing and the galvanostatic intermittent titration technique for these graphite samples as negative electrode materials in battery operation. The results demonstrated that a material having a higher crystalline order exhibits enhanced electrochemical properties when evaluated in terms of rate-capability performance. All these materials were investigated at high C-rates ranging from 0.1C up to 10C. Such improved response was attributed to the crystalline morphology providing short layers, which facilitate rapid Li+ ions diffusivity and electron transport during the course of battery operation. The values obtained for the electrical conductivity of these graphite anodes support this possible explanation.

The initial irreversible capacity, Qi, is one of the parameters to express the material balancing of the cathode to anode. We introduced new terms, which are the initial intercalation Ah efficiency (IIE) and the initial irreversible specific capacity at the surface (Qis), to express precisely the irreversibility of an electrode/electrolyte system. Two terms depended on kinds of active-materials and compositions of the electrode, but did not change with charging state. MPCF had the highest value of IIE and the lowest value of Qis in 1M LiPE6/EC + DEC (1 : 1 volume ratio) electrolyte. IIE value of LiCoO2 electrode was 97-98%, although the preparation condition of the material and the electrolyte were different. Qis value of LiCoO2 was 0~1 mAh/g. MPCF-LiCoO2 cell system had the lowest of the latent capacity. Qis value increased slightly by adding conductive material. IIE and Qis value varied with the electrolyte. By introducing PC to EC+DEC mixed solvent, IIE values were retained, but Qis increased. In case of addition of MP, IIE value increased and Qis value also increased a little.