流变相-喷雾干燥法合成LiCo_(0.3)Ni_(0.7)O_2正极材料的研究

Structure and Electrochemical Properties of LiCo_(0.3)Ni_(0.7)O_2 Prepared by the Rheological Phase and Spray Drying Method

以Co_(0.3)Ni_(0.7)(OH)_2和LiOH·H_O为原料,在含羟基的有机溶剂水溶液中浸渍呈流变相,用喷雾干燥后于空气中在不同的温度下煅烧16h制备层状LiCo_(0.3)Ni_(0.7)O_2正极材料,用XRD、TG-DTA、SEM以及激光粒度测试等表征了材料的晶体结构与理化性能。结果表明,由本法可降低样品合成的反应温度和对反应气氛的严格要求,制备出的样品可有效抑制材料中阳离子混排及非化学计量产物的出现,大大降低材料的首次不可逆放电容量,提高材料的首次放电效率.经700℃煅烧16h合成出的样品首次放电容量达172mAh/g,首次放电效率可达90.8％,循环40次后容量仅衰减9％,显示出优良的电化学性能.

The cathode materials LiCo0.3Ni0.7O2 were prepared from Co0.3Ni0.7(OH)(2) and (LiOHH2O)-H-. dispersed in the organic solution by the rheological phase and spray drying method in air at different sintering temperature for 16h. The TG-DTA analysis, XRD analysis, SEM and electrochemical tests were used to study the physical and the electrochemical performances of the materials. The results indicate that molecular level completely mixing of the raw materials of samples made by our method makes the sintering temperature drop to a lower temperature and the resulted sample has an excellent layered structure and the cation mixing and nonstoichiometric products are effectively restrained when sintered at 700degreesC. The material (sintered at 700degreesC) cycled between 2.80similar to4.25V shows a high initial capacity of 172mAh/g with an efficiency of 90.8% and its irreversible capacity only 16mAh/g. 91% of the initial discharge capacity remains after 40 cycles.