LiNiPO<sub<4</sub<前驱体固相反应合成动力学及电容性能
The Process Reaction Kinetics of Synthesis and Capacitance Performance of LiNiPO<sub<4</sub< from a Precursor via Solid-State Reaction
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摘要: 以氢氧化锂、磷酸二氢铵和醋酸镍为原料,以聚乙二醇PEG-400为表面活性剂,采用前驱体固相活化法制备LiNiPO<sub<4</sub<纳米晶材料,固相制备过程的活化能<em<E</em<=81.08 kJ·mol<sup<-1</sup<,过程动力学为二维相界面扩散反应机理. 但前驱体生成LiNiPO<sub<4</sub<的反应符合界面反应的指数成核机理,活化能<em<E</em<<sub<1</sub<=11.82 kJ·mol<sup<-1</sup<,指前因子ln<em<A</em<=13.82;LiNiPO<sub<4</sub<晶体生长过程中的活化能<em<E</em<<sub<2</sub<=17.73 kJ·mol<sup<-1</sup<;Li<sub<3</sub<PO<sub<4</sub<转化反应和反应体系物系晶化过程符合二维相界面扩散反应机理,是制备过程可控制的重要步骤. 材料LiNiPO<sub<4</sub<+Nafion/C复合电极在0.5 mol·L<sup<-1</sup< H<sub<2</sub<SO<sub<4</sub<中具有典型的电容性能,电极比容量约为214 F·g<sup<-1</sup<,经1 000次循环,电极电容量还略有增加,是潜在的电容器材料.BP)以氢氧化锂、磷酸二氢铵和醋酸镍为原料,以聚乙二醇PEG-400为表面活性剂,采用前驱体固相活化法制备LiNiPO<sub<4</sub<纳米晶材料. 固相制备过程的活化能<em<E</em<=81.08 kJ·mol<sup<-1</sup<,过程动力学为二维相界面扩散反应机理. 前驱体生成LiNiPO<sub<4</sub<的反应符合界面反应指数成核机理,活化能<em<E</em<<sub<1</sub<=11.82 kJ·mol<sup<-1</sup<,指前因子ln <em<A</em<=13.82;LiNiPO<sub<4</sub<晶体生长过程具有较小的活化能<em<E</em<<sub<2</sub<=17.73 kJ·mol<sup<-1</sup<;Li<sub<3</sub<PO<sub<4</sub<转化反应和反应体系物系晶化过程符合二维相界面扩散反应机理,其是制备过程可控制的重要步骤. 材料复合电极LiNiPO<sub<4</sub<+Nafion/C在0.5 mol·L<sup<-1</sup< H<sub<2</sub<SO<sub<4</sub<中具有典型的电容性能,电极比电容为214 F·g<sup<-1</sup<, 经1 000次循环,电极电容量不但没有衰减反而略有增加,是潜在的电容器材料.Abstract: The nano-crystallite LiNiPO<sub<4</sub< powder was synthesized via solid-state reaction of the precursor NH<sub<4</sub<NiPO<sub<4</sub< using raw materials LiOH, NH<sub<3</sub<H<sub<2</sub<PO<sub<4</sub< and NiAc<sub<2</sub<·4H<sub<2</sub<O by adding surfactant PEG-400. The results showed that the process kinetics mechanism of LiNiPO<sub<4</sub< crystals was two-dimensional interface diffusion and the reaction activation energy <em<E</em< was 81.08 kJ·mol<sup<-1</sup<. The formation of amorphous LiNiPO<sub<4</sub< from the precursor consists with the interfacial reaction mechanism of the index nucleation which the activation energy <em<E</em<<sub<1</sub< was 11.82 kJ·mol<sup<-1</sup< and logarithm of exponential factor ln <em<A</em< was 13.82. The process of crystal LiNiPO<sub<4</sub< growth had smaller activation energy <em<E</em<<sub<2</sub< of 17.73 kJ·mol<sup<-1</sup<. The key controllable steps in whole prepared processes are the conversion reaction and crystallization of LiNiPO<sub<4</sub<. LiNiPO<sub<4</sub<+Nafion/C composite electrode in sulfuric acid solution (0.5 mol·L<sup<-1</sup<) has typical capacitance properties and the specific discharge capacity was 214 F·g<sup<-1</sup<. After 1 000 times discharge and charge cycling, the electrode discharge capacity increased slightly instead of attenuation. Results show that the LiNiPO<sub<4</sub<+Nafion/C composite could be applied as the potential material for capacitor.
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