【摘要】：鋰離子電池在新能源領域迅速發(fā)展,其安全性很重要,特別是電池內部的短路問題。隔膜是鋰離子電池結構中不可或缺的組件材料,隔膜主要作用是阻隔正極與負極接觸以防止短路,為鋰離子在電解液中遷移提供通道,防止電流過大致使電池燃燒或爆炸。目前市場上應用最廣的電池隔膜材料是聚乙烯(PE)與聚丙烯隔膜(PP),盡管其具有耐酸堿腐蝕性好、防水無毒、化學穩(wěn)定性較好和廉價易得等優(yōu)點,但其較差的熱穩(wěn)定性嚴重影響到了兩電極之間的隔離,甚至會引起安全事故的發(fā)生。另外,聚烯烴固有的疏水性質可能導致部分鋰離子難以通過聚烯烴隔膜,而且聚烯烴隔膜的孔徑難以滿足大功率電池快速充放電的需要。因此,為了克服聚烯烴隔膜的這些缺點,本文研究了含聚酰亞胺鋰離子電池隔膜,并對其表面形貌、熱收縮性能、吸液率、孔隙率、離子電導率、電化學穩(wěn)定性等性能進行分析,并將隔膜組裝成扣式電池,測試其對電池性能的影響。(1)通過在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納米顆粒和耐高溫材料聚酰亞胺(PI)得到制膜液,將制膜液均勻地涂覆在潔凈的玻璃板上,利用HF溶液除去SiO2納米顆粒獲得具有優(yōu)異耐熱性的PI微孔膜。結果表明：與PP隔膜在150℃收縮40%比較,PI隔膜在150℃不發(fā)生收縮。確定52%為SiO2納米顆粒最佳摻雜量,吸液率與孔隙率分別提高為31%和4%,離子電導率為0.308S/m,組裝成電池首次放電比容量為139mAh/g,90次循環(huán)后容量保持率為89.9%。(2)利用PI作為粘結劑,將不同粒徑的SiO2納米顆粒與PI按9：1混合涂覆在PP隔膜兩側,制備得到陶瓷涂層復合隔膜。結果表明：確定30nmSiO2涂覆后的復合隔膜電化學性能達到最優(yōu)。與PP隔膜在150℃橫向收縮23.7%,縱向收縮18%比較,復合隔膜在150℃基本不發(fā)生收縮。吸液率提高59%,孔隙率為42.6%,離子電導率為0.376S/m,組裝成電池首次放電比容量為139.4mAh/g,100次循環(huán)后容量保持率為94.7%。(3)將同一粒徑的CaCO3納米顆粒與粘合劑PI按不同比例涂覆在PP隔膜上,利用HAc去除CaCO3后得到PP/PI復合隔膜。結果表明：確定30%PI涂層改性后的復合隔膜電化學性能達到最優(yōu)。與PP隔膜在150℃橫向收縮23.7%,縱向收縮18%比較,復合隔膜分別為3.4%與3.8%。吸液率提高15%,孔隙率為42.8%,離子電導率為0.226S/m,組裝成電池首次放電比容量為138.7mAh/g,100次循環(huán)后容量保持率為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，

本文編號：2279744