Synthesis and Properties of LiNi0.8Co0.2O2 Powders by Modified Pechini Method

• Main Authors: Hui-Ling Fang, 方惠齡
• Other Authors: Wein-Duo Yang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/08059040355464438175

碩士 === 國立高雄應用科技大學 === 化學工程系碩士班 === 95 === LiNi0.8Co0.2O2 materials have been produced from the resins synthesized from the polymerized complex technique based on Pechini method. Mixtures of nitrates were dissolved in a water solution containing citric acid, and cellulose was used to produce the resin from polyesterification between citric acid and cellulose. The precursor has been characterized by DTA/TGA, BET, XRD and SEM, and those mechanisms for the evolution of LiNi0.8Co0.2O2 powders in this process was proposed and discussed in the context of the microstructure. LiNi0.8Co0.2O2 obtained from molar ratio of citric acid/metal ions at 1 demonstrated a smaller particle size of 30-50 nm and exhibited a pure phase of ilmenite as calcined at 600℃ for 4 hours. Powders properties of the materials have significiant effected by the calcination time and calcination temperature. The best conditions of heat treatment for the layer-structrual LiNi0.8Co0.2O2 was calcination at 800℃ for 12 hours. Furthermore, the surface response method (include Box-Behnken design) was applied to deal the preparatory conditions of the sol-synthesized process, and the optimal preparatory conditions have been obtained. It indicates that the gel prepared from the molar ratio of citric acid/metal ions at 1.01, the molar ratio of water/citric acid at 26.57 , the molar ratio of cellulose/mental ions at 5×10-6 and gelated at 83oC, a minimum particle size of LiNi0.8Co0.2O2 powders was examined. The particle size is about 70 nm. Finally, the pH of the electrolyte solution has relationships with the stability of LiNi0.8Co0.2O2 and investigated by cycling voltammetry. The materials were more stable in the pH of electrolyte solution more than 7.