Fabrication of Ni-, Co- and NiCo-coated graphite microspheres by heterogeneous precipitation

Abstract

The precursors with NiCO₃·2Ni(OH)₂·2H₂O, Co₂(OH)₂CO₃, or both NiCO₃·2Ni(OH)₂·2H₂O and Co₂(OH)₂CO₃ coated graphite microspheres were prepared respectively by the aqueous heterogeneous precipitation using nickel sulfate, cobalt nitrate, sodium carbonate, ammonium bicarbonate and graphite microspheres as the main starting materials. Subsequently, Ni-, Co- and NiCo-coated graphite microspheres were successfully obtained by thermal reduction of the as-prepared precursors at 500 °C for 2 h, respectively. These metal-coated graphite microspheres were characterized with a smooth, cohesive surface consisting of fine metallic particles. Optimized precipitation processing parameters of the concentration of graphite microspheres (10 g/L), the rate of adding reactants (3 mL/min) and pH value (8.0) were determined by a trial and error method. The thermal analysis of the precursors was investigated by TG. Powders of the precursors and the resultant metal-(Ni, Co and NiCo alloy) coated graphite microspheres were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD).

Keywords

graphite microsphere / metal-coated / heterogeneous precipitation / lithium ion battery

References

[1] Liu Z. L., Yu A. S., Lee J. Y. Modifications of Synthetic Graphite for Secondary Lithium-ion Battery Applications[J]. Journal of Power Sources, 1999, 81–82: 187

[2] Lu W., Donepudi V. S., Prakash J., . Electrochemical and Thermal Behavior of Copper Coated Type MAG-20 Natural Graphite[J]. Electrochimica Acta, 2002, 47: 1 601

[3] Choi W. C., Byun D. J., Lee J. K., . Electrochemical Characteristics of Silver- and Nickel-coated Synthetic Graphite Prepared by a Gas Suspension Spray Coating Method for the Anode of Lithium Secondary Batteries[J]. Electrochimica Acta, 2004, 50: 523

[4] Yu Z. H., Wu F., Ren X. M. Study on the Anode of Lithium-ion Battery (I)-the Modification of Carbon Anode by Plating[J]. Battery Bimonthly, 2002, 32: 65

[5] Buqa H., Würsig A., Vetter J., . SEI Film Formation on Highly Crystalline Graphitic Materials in Lithium-ion Batteries[ J]. Journal of Power Sources, 2006, 153: 385

[6] Zhang S. S. Electrochemical Study of the Formation of a Solid Electrolyte Interface on Graphite in a LiBC₂O₄F₂-based Electrolyte[J]. Journal of Power Sources, 2007, 163: 713

[7] Wu Y. P., Jiang C., Wan C., . Anode Materials for Lithium Ion Batteries from Mild Oxidation of Natural Graphite[J]. Journal of Applied Electrochemistry, 2002, 32: 1 011

[8] Zhao H. P., Ren J. G., He X. M., . Purification and Carbon-film-coating of Natural Graphite as Anode Materials for Li-ion Batteries[J]. Electrochimica Acta, 2007, 52: 6 006

[9] Li Y., Tu J. P., Shi D. Q., . DC Magnetron Sputtering Prepared Ag-C Thin Film Anode for Thin Film Lithium Ion Microbatteries[J]. Journal of Alloys and Compounds, 2007, 436: 290

[10] Shi L. H., Wang Q., Li H., . Electrochemical Performance of Ni-deposited Anodes for Lithium Secondary Batteries[J]. Journal of Power Sources, 2001, 102: 60

[11] Fu L. J., Liu H., Li C., . Surface Modifications of Electrode Materials for Lithium Ion Batteries[J]. Solid State Sciences, 2006, 8: 113

[12] Shen X. Q., Jing M. X., Li W. X., . Fabrication of Fe-, Ni and FeNi-coated Al₂O₃ Core-shell Microspheres by Heterogeneous Precipitation[J]. Powder Technology, 2005, 160: 229

[13] Li Y. D., He Y. P., Li L. Q., . Fabrication of Co₃O₄ Ultrafines by a Liquid-control-precipitation Method[J]. Chemical Journal of Chinese Universities, 1999, 20(4): 519

[14] Nomura T., Alonso M., Kousaka Y., . A model for Simultaneous Homogeneous and Heterogeneous Nucleation[J]. Journal of Colloid and Interface Science, 1998, 203: 170