【作者】 张淑静；

【导师】 钟盛文；

【作者基本信息】 江西理工大学 ， 应用化学， 2007， 硕士

【摘要】 三元正极材料LiNi_1/3Co_1/3Mn_1/3O₂（L333）是近年来新涌现的电池材料,由于比容量高、循环性能好、成本较LiCoO₂低等优势,有希望成为电动汽车或混合电动汽车的动力电池材料。因此,研究LiNi_1/3Co_1/3Mn_1/3O₂与其它正极材料共混的电池性能,对发展新型动力电池有重要意义。本论文利用LiNi_1/3Co_1/3Mn_1/3O₂容量高和LiMn₂O₄稳定性高的优势,将两者混合使用,系统研究了LiNi_1/3Co_1/3Mn_1/3O₂和LiMn₂O₄共混材料的循环性能和安全性能。采用AA型电池对锂离子共混正极材料进行循环性能的测试。通过实验研究表明: 91（90%L333+10%LiMn₂O₄）、82（80%L333+20%LiMn₂O₄）、73（70%L333+30%LiMn₂O₄）和55（50%L333+50%LiMn₂O₄）材料放电的比容量分别为147.9mAh/g、137.7mAh/g、134mAh/g和121mAh/g。LiNi_1/3Co_1/3Mn_1/3O₂和LiMn₂O₄共混材料有良好的电化学性能。在1C、2.75⁴.2V的充电制度下, 82和73材料的循环性能与已经商品化的LiCoO₂相当,并且大电流放电后容量恢复率好。同时实验研究了在室温下循的LiNi_1/3Co_1/3Mn_1/3O₂及其共混材料电池的容量衰减主要是由于正极材料的性能恶化造成的。通过对共混材料的安全性研究表明,LiNi_1/3Co_1/3Mn_1/3O₂正极材料中添加LiMn₂O₄可使电池的安全性有很大程度的改善。MCMB/91、MCMB/82、MCMB/73和MCMB/55电池最高分别可以通过3C5V、3C10V、3C15V、3C15V的过充;LiMn₂O₄、73和55的过充稳定性较高;通过SEM和XRD的检测得出共混材料耐过充性差异是脱锂态L333正极材料不稳定性造成的;采用适当的充电模式,避免高倍率充电,是防止电池爆炸的关键;适当的正负极容量匹配可以提高电池的耐过充性。MCMB/91、MCMB/82、MCMB/73和MCMB/55电池最高分别可以通过170℃、175℃、175℃和175℃的热箱实验。同时研究发现共混材料锂离子电池在高温下发生爆炸的主要原因是正极材的料分解并参与放热反应引起的。不同比例共混正极材料组装的AA型锂离子电池均通过短路和穿钉实验。更多还原

【Abstract】 The positive electrode material LiNi_1/3Co_1/3Mn_1/3O₂ is the Lithium-ion battery material which newly emerged in recent years. Because of its’high capacity, good cyclic performance, low cost compared to LiCoO₂ and so on, it hopefully come to be in the application of electric vehicles and hybrid electric vehicles. To greatly improve the performance of lithium-ion batteries, we utilize the advantages of LiNi_1/3Co_1/3Mn_1/3O₂ and LiMn₂O₄ and mixed them to improve the materials’integrative characteristics. The cyclic and safety performance of the mixed cathode materials are researched in the paper.To detect the cyclic performance, the mixed cathode materials are assembled to AA-size batteries. The results show that the discharge capacities of the mixed materials 91 （90%L333+10%LiMn₂O₄）、82（80%L333+20%LiMn₂O₄）、73 （70%L333+30%LiMn₂O₄）和55（50%L333+50%LiMn₂O₄） are 147.9mAh/g、137.7mAh/g、134mAh/g and 121mAh/g . The electric performance of 82 and 73 is close to LiCoO₂ which was already put into market. And the capacity fading mechanism of the mixed materials are caused by the deterioration of the cathode materials.The addition of LiMn₂O₄ into LiNi_1/3Co_1/3Mn_1/3O₂ cathode material can improve the safety performance in a deep degree. The overcharge-resistance performance of lithium-ion batteries was detected by overcharging batteries assembled with different cathode materials. MCMB/91、MCMB/82、MCMB/73和MCMB/55 batteries respectively can pass the over-charging at 3C5V、3C10V、3C15V、3C15V, and among them73 and 55 present higher overcharge stability. The major reason for batteries explosion on overcharging was explained by the thermal stability of different delithiation degrees of different cathode materials.Studies on oven experiment indicate that the addition of LiMn₂O₄ to LiNi_1/3Co_1/3Mn_1/3O₂ can improve the thermal stability of the batteries. The main reason for the batteries explosion was the exothermic reaction caused by L333 at high temperatures.In addition, short-circuit and nail penetration performances of AA-size batteries with different cathode materials show different safety. And the mixed cathode materials are also proved to be safe.更多还原