含聚酰亚胺锂离子电池隔膜制备与性能研究

发布时间：2018-10-18 16:47

【摘要】：锂离子电池在新能源领域迅速发展,其安全性很重要,特别是电池内部的短路问题。隔膜是锂离子电池结构中不可或缺的组件材料,隔膜主要作用是阻隔正极与负极接触以防止短路,为锂离子在电解液中迁移提供通道,防止电流过大致使电池燃烧或爆炸。目前市场上应用最广的电池隔膜材料是聚乙烯(PE)与聚丙烯隔膜(PP),尽管其具有耐酸碱腐蚀性好、防水无毒、化学稳定性较好和廉价易得等优点,但其较差的热稳定性严重影响到了两电极之间的隔离,甚至会引起安全事故的发生。另外,聚烯烃固有的疏水性质可能导致部分锂离子难以通过聚烯烃隔膜,而且聚烯烃隔膜的孔径难以满足大功率电池快速充放电的需要。因此,为了克服聚烯烃隔膜的这些缺点,本文研究了含聚酰亚胺锂离子电池隔膜,并对其表面形貌、热收缩性能、吸液率、孔隙率、离子电导率、电化学稳定性等性能进行分析,并将隔膜组装成扣式电池,测试其对电池性能的影响。(1)通过在N-甲基吡咯烷酮(NMP)溶液中按照一定比例混合已分散好的SiO2纳米颗粒和耐高温材料聚酰亚胺(PI)得到制膜液,将制膜液均匀地涂覆在洁净的玻璃板上,利用HF溶液除去SiO2纳米颗粒获得具有优异耐热性的PI微孔膜。结果表明：与PP隔膜在150℃收缩40%比较,PI隔膜在150℃不发生收缩。确定52%为SiO2纳米颗粒最佳掺杂量,吸液率与孔隙率分别提高为31%和4%,离子电导率为0.308S/m,组装成电池首次放电比容量为139mAh/g,90次循环后容量保持率为89.9%。(2)利用PI作为粘结剂,将不同粒径的SiO2纳米颗粒与PI按9：1混合涂覆在PP隔膜两侧,制备得到陶瓷涂层复合隔膜。结果表明：确定30nmSiO2涂覆后的复合隔膜电化学性能达到最优。与PP隔膜在150℃横向收缩23.7%,纵向收缩18%比较,复合隔膜在150℃基本不发生收缩。吸液率提高59%,孔隙率为42.6%,离子电导率为0.376S/m,组装成电池首次放电比容量为139.4mAh/g,100次循环后容量保持率为94.7%。(3)将同一粒径的CaCO3纳米颗粒与粘合剂PI按不同比例涂覆在PP隔膜上,利用HAc去除CaCO3后得到PP/PI复合隔膜。结果表明：确定30%PI涂层改性后的复合隔膜电化学性能达到最优。与PP隔膜在150℃横向收缩23.7%,纵向收缩18%比较,复合隔膜分别为3.4%与3.8%。吸液率提高15%,孔隙率为42.8%,离子电导率为0.226S/m,组装成电池首次放电比容量为138.7mAh/g,100次循环后容量保持率为91.3%。
[Abstract]:Lithium ion battery is developing rapidly in the field of new energy, its safety is very important, especially the problem of short circuit inside battery. Diaphragm is an indispensable component material in the structure of lithium-ion battery. The main function of diaphragm is to prevent the contact between positive and negative electrode to prevent short circuit, to provide a channel for lithium ion to migrate in electrolyte, and to prevent the battery from burning or exploding due to excessive current. At present, the most widely used materials for battery diaphragm are polyethylene (PE) and polypropylene diaphragm (PP), although they have the advantages of good acid-alkali resistance, waterproofing and non-toxicity, good chemical stability and low cost and so on. But its poor thermal stability seriously affects the isolation between the two electrodes, and even causes the occurrence of safety accidents. In addition, the inherent hydrophobic properties of polyolefin may make it difficult for some lithium ions to pass through polyolefin membranes, and the pore size of polyolefin membranes is difficult to meet the needs of rapid charge and discharge of high-power batteries. Therefore, in order to overcome these shortcomings of polyolefin membrane, the membrane of lithium ion battery containing polyimide was studied, and the surface morphology, thermal shrinkage, absorbency, porosity, ionic conductivity of the membrane were studied. Electrochemical stability and other properties are analyzed, and the diaphragm is assembled into a button battery. The effect on the battery performance was tested. (1) the film preparation solution was obtained by mixing dispersed SiO2 nanoparticles and high temperature resistant polyimide (PI) in a certain proportion in N-methylpyrrolidone (NMP) solution. The film making solution was uniformly coated on the clean glass plate and the SiO2 microporous film with excellent heat resistance was obtained by removing SiO2 nanoparticles from the SiO2 solution. The results showed that the PI diaphragm did not shrink at 150 鈩，

本文编号：2279744