共沉淀反应时间对LiNi0.5Co0.2Mn0.3O2正极材料形貌和电化学性能的影响

Effect of Reaction Time of Coprecipitation on Morphology and Electrochemical Properties of LiNi0.5Co0.2Mn0.3O2 Cathode Material

采用共沉淀法制备Ni0.5Co0.2Mn0.3(OH)2前驱体,并通过高温固相法合成LiNi0.5Co0.2Mn0.3O2正极材料,研究了反应时间对Ni0.5Co0.2Mn0.3(OH)2前驱体和LiNi0.5Co0.2Mn0.3O2正极材料的形貌、结构以及电化学性能的影响。结果表明,随着反应时间增加,前驱体和正极材料的二次颗粒粒径逐渐增大;若反应时间过短,二次颗粒粒径小,易加剧电化学循环过程中材料与电解液的副反应,正极材料循环性能较差;若反应时间过长,二次颗粒粒径过大,增加了锂离子扩散路径,也不利于正极材料在高倍率下的循环。反应16 h制备的LiNi0.5Co0.2Mn0.3O2正极材料具有适中的颗粒粒径,拥有优异的电化学性能,在1C倍率经过180圈循环容量保持率可达75.3%,5C倍率经过300圈循环容量保持率可达56.0%。

Ni0.5Co0.2Mn0.3(OH)2 precursor was prepared by coprecipitation process, and LiNi0.5Co0.2Mn0.3O2 cathode material was synthesized by a high-temperature solid-state method. The effect of reaction time on the morphology, structure and electrochemical properties of Ni0.5Co0.2Mn0.3(OH)2 precursor and LiNi0.5Co0.2Mn0.3O2 cathode materials were investigated. Results show that with the increase of reaction time, the secondary particle sizes of precursor and material are gradually increased. If the reaction time is too short, the secondary particle size will be small, which is prone to aggravate the side reaction between electrode and electrolyte during the electrochemical cycle, leading to the deterioration of the capacity retention of the material. However, a too long time of reaction will result in secondary particle size being too large, which increases the lithium ion diffusion path and is not beneficial to the capacity retention of the cathode at a high rate. The LiNi0.5Co0.2Mn0.3O2 cathode material prepared with 16 h reaction time has the moderate particle size and an excellent electrochemical performance, with 75.3% capacity retention after 180 cycles at 1 C rate and 56.0% capacity retention after 300 cycles at 5 C rate.