Modification of natural graphite using pitch through dynamical melt-carbonization

Abstract

The graphite was modified using pitch through dynamical melt-carbonization, and the effects of modification temperature and the amount of pitch on the characteristics of graphite were investigated. The structure and characteristics of the graphite were determined by X-ray diffractometry(XRD), scanning electron microscopy(SEM), particle size analysis and electrochemical measurements. The results show that the modified graphite has a disordered carbon/graphite composite structure, larger average particle diameter, greater tap density, and better electrochemical characteristics than the untreated graphite. The sample coated with 10% pitch dynamical melt-carbonized at 400 °C for 3 h and heat-treated at 850 °C for 2 h has better electrochemical performances with a reversible capacity of 360.5 mA·h/g, a irreversible capacity of 41.0 mA·h/g, and an initial coulombic efficiency of 89.8% compared with natural graphite and disordered carbon. The cycling stability of the Li/C cell with modified graphite as anodes is improved, and its capacity retention ratio at the 30th cycle is up to 94.37%.

Keywords

lithium ion battery / graphite / dynamical melt-carbonization / anode

References

[1] GuoH.-j., LiX.-h., WangZ.-x., et al.. Mild oxidation treatment of graphite anode for Li-ion batteries[J]. J Cent South Univ Technol, 2005, 12(1): 50-54

[2] HongyuW., MasakiY., TakeshiA., et al.. Characterization of carbon-coated natural graphite as a lithium ion battery anode material[J]. J Electrochem Soc, 2002, 149(4): 499-503

[3] GuoH.-j., LiX.-h., WangZ.-x., et al.. Effect of lithium or aluminum substitution on the characteristics of graphite for anode of lithium ion batteries[J]. Rare Metals, 2003, 22(4): 280-284

[4] KatsunoriY., AtsushiY., YoshinoriK., et al.. Carbon hybrids graphite hard carbon and graphite coke as negative electrode batteries materials for lithium secondary batteries charge/discharge characteristics[J]. J Electrochem Soc, 2002, 149(7): A804-A807

[5] HossainS., YongkyuK., SalehY., et al.. Comparative studies of MCMB and C-C composite as anodes for lithium-ion systems[J]. J Power Sources, 2003, 114(2): 264-276

[6] FeyT. K., LeeD. C., LinY. Y., et al.. High-capacity disordered carbons derived from peanut shells as lithium-intercalating anode materials[J]. Synthetic Metals, 2003, 139(1): 71-78

[7] ShiH.. Coke vs. graphite as anodes for lithium-ion batteries[J]. J Power Sources, 1998, 75(1): 64-72

[8] MenachemC., WangY., FlowersJ., et al.. Characterization of lithiated natural graphite before and after mild oxidation[J]. J Power Sources, 1998, 76(2): 180-185

[9] HuangH., LiuW.-t., HuangX.-j., et al.. Effect of a rhombohedral phase on lithium intercalation capacity in graphite[J]. Solid State Ionics, 1998, 110(3/4): 173-178

[10] SuzukiK., HamadaT., SugiuraT.. Effect of graphite structure on initial irreversible reaction in graphite anodes[J]. J Electrochem Soc, 1999, 146(3): 890-897

[11] BeguinF., ChevallierF., VixC., et al.. A better understanding of the irreversible lithium insertion mechanisms in disordered carbons[J]. Journal of Physics and Chemistry of Solids, 2004, 65(2/3): 211-217

[12] YoshioM., WangH., FukudaK., et al.. Effect of carbon coating on electrochemical performance of treated natural graphite as lithium-ion battery anode material[J]. J Electrochem Soc, 2000, 147(4): 1245-1250

[13] DingY. S., LiW. N., SantoI., et al.. Characteristics of graphite anode modified by CVD carbon coating[J]. Surface & Coatings Technology, 2006, 200(9): 3041-3048

[14] ShuJ., LiH., YangR.-z., et al.. Cage-like carbon nanotubes/Si composite as anode material for lithium ion batteries[J]. Electrochemistry Communications, 2006, 8(1): 51-54

[15] GuoH.-j., LiX.-h., WangZ.-x., et al.. Si-doped composite carbon as anode of lithium ion batteries[J]. Transactions of Nonferrous Metals Society of China, 2003, 13(5): 1062-1065

[16] ChungG. C., JunS. H., LeeK. Y., et al.. Effect of surface structure on the irreversible capacity of various graphitic carbon electrodes[J]. J Electrochem Soc, 1999, 146(5): 1664-1671

[17] ZaghibK., NadeauG., KinoshitaK.. Effect of graphite particle size on irreversible capacity loss[J]. J Electrochem Soc, 2000, 147(6): 2110-2115

[18] WangG.-p., ZhangB.-l., YueM., et al.. A modified graphite anode with high initial efficiency and excellent cycle life expectation[J]. Solid State Ionics, 2005, 176(9/10): 905-909