新型聚芳醚砜锂离子电池隔膜的制备及性能

Preparation and performance of a novel polyarylethersulfone separator for lithium-ion batteries

利用非溶剂致相分离法(NIPS)制备新型结构聚芳醚砜(BDD)锂离子电池隔膜,详细考察溶剂种类、聚合物含量、凝固浴组成以及铸膜液在空气中的停留时间等因素对隔膜微结构和性能的影响,得出最佳成膜条件:溶剂为磷酸三乙酯(TEP),聚合物质量分数为20%,凝固浴为水/异丙醇=4/6(质量比),停留时间为20 s.对最佳成膜条件下隔膜进行测试发现,与聚丙烯(PP)隔膜相比,BDD隔膜具有更高的孔隙率、吸液率以及离子电导率,分别达到了90.52%、377.76%和0.92 mS/cm,且热稳定性能优异.该隔膜所组装的锂离子电池在0.2 C电流密度下达到了141.2 mA·h/g的放电比容量,高于PP的123.7 mA·h/g,表现出优异的倍率性能;同时在0.5 C电流密度下循环100圈后,容量保持率达到了92.3%,说明具有优异的循环性能.

By using the non-solvent induced phase separation(NIPS)method to prepare a new-structure polyarylethersulfone(BDD)lithium ion battery separator,this paper has a detailed exploration of the factors such as the type of solvent,polymer concentration,coagulation bath composition and the residence time of the casting liquid in the air(T)on the microstructure and performance of the separator film,which helps to work out the best film forming conditions:the solvent should be TEP,the polymer concentration should be 20%,the coagulation bath should be water and isopropanol in the proportion of 4∶6,and the residence time of the casting liquid in the air should be 20 seconds.The separator is tested under the optimal film-forming conditions,and it is found that,compared with the PP separator,the BDD separator has higher porosity,liquid-absorbing ratio and ionic conductivity reaching 90.52%,377.76%and 0.92 mS/cm as well as excellent thermal stability.The lithium-ion battery assembled by the polyarylethersulfone separator has reached a discharge specific capacity of 141.2 mA·h/g at a current density of 0.2 C,which is higher than the 123.7 mA·h/g of PP,showing excellent rate performance.Meanwhile,the capacity retention rate reaches 92.3%after 100 cycles under 0.5 C,showing excellent cycle performance.