CAJ | 학술논문

根据同时平衡原理和质量守恒原理,推导Ni(Ⅱ)-Co(Ⅱ)-C2O42--NH3-NH4+-H2O反应体系中金属离子和草酸盐在常温水溶液中的热力学平衡方程,计算并绘制该体系的1g[Me2+]T-pH图.结果表明,在水溶液中,当pH值小于5.0时,溶液中镍离子和钴离子以设定配比转移到前驱体粉末中,前驱体的形貌为粒状聚集体;当pH值大于5.0时,由于Ni(NH3)n2+和Co(NH3)n2+(n=1-6)离子的形成,前驱体粉末中镍钴配比不能维持料液中设定的配比值,前驱体在pH为5.0-8.0范围内呈现棒状形貌,而在pH>8.0时为纤维状形貌.改变沉淀介质可以在pH为2.0-8.6范围内获得配比准确、成分均匀的纤维状镍钴合金前驱体.
근거동시평형원리화질량수항원리,추도Ni(Ⅱ)-Co(Ⅱ)-C2O42--NH3-NH4+-H2O반응체계중금속리자화초산염재상온수용액중적열역학평형방정,계산병회제해체계적1g[Me2+]T-pH도.결과표명,재수용액중,당pH치소우5.0시,용액중얼리자화고리자이설정배비전이도전구체분말중,전구체적형모위립상취집체;당pH치대우5.0시,유우Ni(NH3)n2+화Co(NH3)n2+(n=1-6)리자적형성,전구체분말중얼고배비불능유지료액중설정적배비치,전구체재pH위5.0-8.0범위내정현봉상형모,이재pH>8.0시위섬유상형모.개변침정개질가이재pH위2.0-8.6범위내획득배비준학、성분균균적섬유상얼고합금전구체.
According to the principles of simultaneous equilibrium and mass equilibrium, a series of thermodynamic equilibrium equations in Ni(Ⅱ)-Co(Ⅱ)-C2O42--NH3-NH4+-H2O system at ambient temperature were deduced. The diagrams of logarithm ion concentrations versus pH values at different solution compositions were drawn. The results show that Ni2+ and Co2+ can completely precipitate at pH less than 5.0 and the predefined Ni/Co ratios can be well kept in the precursor. The precursor morphology is granular aggregation. However, rod aggregation precursor is obtained in the pH range of 5.0-8.0, and fibre-shape precursor is got at pH value higher than 8.0. The Ni/Co ratios in the above two precursors are not reproduced as that in the feed due to the formation of multi-coordinated Ni(NH3)n2+ and Co(NH3)n2+ (n=1-6). Modification of precipitation medium is favorable for the precursors to keep the predefined Ni/Co ratios of the feed in the pH range of 2.0-8.6. Meanwhile, the precursors with fibrous morphology can be obtained.