Mild oxidation treatment of graphite anode for Li-ion batteries

Abstract

The graphite was modified by mild oxidation, and the effects of modification temperature and soaking time on the characteristics of graphite were investigated. The structure and characteristics of the graphite were determined by X-ray diffraction, scanning electron microscopy, BET surface area, particle size analysis and electrochemical measurements. The results show that the modified graphite has a better-developed crystallite structure, larger average particle diameter, smaller surface area, and better electrochemical characteristics than the untrented graphite. The sample mild-oxidized at 600 °C for 3 h has the best electrochemical performances with a reversible capacity of 304.5 mA·h/g, a irreversible capacity of 66.4 mA·h/g, and a initial coulmbic efficiency of 82.1%. The charge/discharge properties and a cycling stability of the prototype lithium ion batteries with modified graphite as anodes are improved. Its capacity retention ratio at the 200th cycle is enhanced from 66.75% to 90.15%.

Keywords

graphite / anode / lithium ion battery / capacity

References

[1] MoriY, IriyamaT, HashimotoT, et al.. Lithium doping/undoping in disordered coke carbons[J]. Journal of Power Sources, 1995, 56: 205-208

[2] BuielE, DahnJ R. Reduction of the irreversible capacity in hard-carbon anode materials prepared from sucrose for li-ion batteries[J]. J Electrochem Soc, 1998, 145(6): 1977-1981

[3] TokumitsuK, MabuchiA, FujimotaH, et al.. Electrochemical insertion of lithium into carbon synthesized from condensed aromatics[J]. J Electrochem Soc, 1996, 143(7): 2235-2239

[4] MabuchiA, TokumitsuK, FujimotoH, et al.. Charge-discharge characteristics of the mesocarbon microbeads heat-treated at different temperatures[J]. J Electrochem Soc, 1995, 142(4): 1041-1046

[5] ShiH. Coke vs. graphite as anodes for lithium-ion batteries[J]. Journal of Power Sources, 1998, 75: 64-72

[6] MenachemC, WangY, PeledE, et al.. Characterization of lithiated natural graphite before and after mild oxidation [J]. Journal of Power Sources, 1998, 76: 180-185

[7] HuangH, LiuW, HuangX, et al.. Effect of a rhombohedral phase on lithium intercalation capacity in graphite [J]. Solid State Ionics, 1998, 110: 173-178

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

[9] ChungG C, KimH J, YuS, et al.. Origin of graphite exfoliation—An investigation of the important role of solvent cointercalation[J]. J Electrochem Soc, 2000, 147(12): 4391-4398

[10] 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

[11] 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

[12] PeledE, MenachemC, Bar-TowD, et al.. Improved graphite anode for lithium-ion batteries[J]. J Electrochem Soc, 1996, 143(1): L4-L7

[13] GuoH J, LiX H, WangZ X, et al.. Si-doped composite carbon as anode of lithium ion batteries [J]. Trans Nonferrous Met Soc China, 2003, 13(5): 1062-1065

[14] Ein-EliY, KochV R. Chemical oxidation: a route to enhanced capacity in li-ion graphite anodes[J]. J Electrochem Soc, 1997, 144(9): 2968-2973

[15] KuribayashiI, YokoyamaM, YamashitaM. Battery characteristics with various carbonaceous materials [J]. Journal of Power Sources, 1995, 54: 1-5

[16] YuP, RitterJ A, WhiteR E, et al.. Ni-composite microencapsulated graphite as the negative electrode in lithium-ion batteries-I: Initial irreversible capacity study[J]. J Electrochem Soc, 2000, 147(4): 1280-1285