Template growth mechanism of spherical Ni(OH)₂

Abstract

The microstructures and growth process characteristics of spherical Ni(OH)₂ particles synthesized by the aqueous precipitation-crystallization method were investigated by SEM, TEM and XRD, and their growth mechanism was discussed. With the reaction beginning and continuing, amorphous Ni(OH)₂ nano-crystallites grow up to spherical micron-particles with radially arranged crystallites. The nucleation, crystallization and re-crystallization led by Ostwald ripening simultaneously take place through the whole growth processes. With the course from reversible aggregation to irreversible agglomeration, the Ni(OH)₂ particles tend to grow according to the template growth model: the growth on the crystallite templates stretching in the radius directions is free and quick, while the growth rate for crystallites in other directions is confined due to lower monomers concentration and tends to dissolve. So it is only the radially arranged crystallites that predominate in the particle and lead to characteristic microstructures.

Keywords

spherical Ni(OH)₂ / microstructure / Ostwald ripening / growth mechanism / crystallization

References

[1] SrinivasanV., WeidnerJ. W., WhiteR. E.. Mathematical models of the nickel hydroxide active materials[J]. J Solid State Electrochem, 2000, 4(2): 367-382

[2] WuB., WhiteR. E.. Modeling of a nickel hydrogen cell: phase reactions in the nickel active material[J]. J Electrochem Soc, 2001, 148(6): A595-A609

[3] WeidnerJ. W., TimmermannP.. Effect of proton diffusion, electron conductivity and charge transfer resistance on nickel hydroxide discharge curves[J]. J Electrochem Soc, 1994, 141(3): 346-351

[4] MaoZ., VidtsD. P., WhiteR. E.. Theoretical analysis of the discharge performance of a NiOOH/H₂ cell[J]. J Electrochem Soc, 1994, 141(1): 54-64

[5] SongQ.-s., TangZ.-y., GuoH.-t., et al.. Structural characteristics of nickel hydroxide synthesized by a chemical precipitation route under different pH values[J]. J Power Sources, 2002, 112(2): 428-434

[6] WatanabeK., KikuokaT.. Physical and electrochemical characteristics of nickel hydroxide as a positive material for rechargeable alkaline batteries[J]. J Appl Electrochem, 1995, 25(2): 219-226

[7] AcharyaR., SubbaiahT., AnandS., et al.. Effect of precipitating agents on the physicochemical and electrolytic characteristics of nickel hydroxide[J]. Materials Letter, 2003, 57(20): 3089-3095

[8] PengM.-X., WangL.-s., ShenX.-q., et al.. Microstructures and formation mechanism of spherical β-Ni(OH)₂[J]. The Chinese Journal of Nonferrous Metals, 2003, 13(5): 1130-1135

[9] FangK.-ming.. Study on microstructure of powder particles by TEM[J]. China Powder Science and Technology, 1999, 10(5): 8-10

[10] XiaH., AllmangM. Z.. Rate equation approach to the late stages of cluster ripening[J]. Physica A: Statistical and Theoretical Physics, 1998, 261(4): 176-187

[11] KaminskiA. Y., SurisR. A.. Smoothing of crystal surfaces during growth interruption[J]. Applied Surface Science, 1996, 104/105: 312-316

[12] ZhangK.-c., ZhangL.-hui.Crystal Growth Science and Technology(Vol.1)[M], 1997, Beijing, Science Press

[13] ShenX.-q., PengM.-x., JingM.-x., et al.. Formation of microstructures for spherical Ni(OH)₂ particles[J]. J Functional Materials, 2005, 36(10): 1629-1633

[14] JiaZ.-q., LiuZ.-zhou.. Process characteristics and principles of synthesis of nanosized particles by liquid precipitation methods[J]. Chinese Journal of Chemical Engineering, 2002, 30(1): 15-41

[15] Delahaye-vidalA., BeaudoinB., Sac-EpeeN., et al.. Structural and textural investigations of the nickel hydroxide electrode[J]. Solid State Ionics, 1996, 84(4): 239-248

[16] HorstJ. H. T., KramerH. J. M., RosmalenG. M. V., et al.. Molecular modeling of the crystallization of polymorphs. Part I: The morphology of HMX polymorphs[J]. J Crystal Growth, 2002, 237/239: 2215-2220

[17] PengM.-x., ShenX.-q., WangL.-s., et al.. Structural characteristics of spherical Ni(OH)₂ and its charge/discharge process[J]. Journal of Central South University of Technology, 2005, 12(1): 5-8