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Mechanically and thermally robust microporous copolymer separators for lithium ion batteries
Electrochimica Acta ( IF 6.6 ) Pub Date : 2022-06-12 , DOI: 10.1016/j.electacta.2022.140705
Alexander J. Manly, Wyatt E. Tenhaeff

Next generation, multifunctional separators can enhance energy storage, power, and safety performance of lithium ion batteries but must be simple to fabricate and incorporate with existing roll-to-roll manufacturing. This study presents a strategy to facilely prepare these separators using UV-initiated polymerization-induced phase separation (PIPS), wherein microporous polymer separators are fabricated directly from constituent monomers and ethylene carbonate (EC) porogen. This enables a wide compositional design space as co-monomers with specific chemical functionality can be readily incorporated into the PIPS precursor mixture. Herein, 1,4-butanediol diacrylate (BDDA) was copolymerized with poly(ethylene glycol) diacrylate (PEGDA) to increase the acrylate conversion in the photopolymerization and improve mechanical properties. By tuning the ratio of PEGDA and EC, separators with high porosity (41.3%) and effective ionic conductivity (2.09 mS cm−1) were prepared. Inclusion of PEGDA was essential to increasing the elastic modulus to > 345 MPa, which is required for cell assembly by roll-to-roll manufacturing. All separators prepared were shown to enable reversible cycling of lithium metal/LiNi0.5Mn0.3Co0.2O2 half-cells for 100 cycles. Unlike conventional polyolefin separators, which were shown to melt at 160 °C and shrink by up to 29.8% at elevated temperatures, the PIPS separators possess exceptional, safety-enhancing thermomechanical properties, undergoing no phase transitions or thermal shrinkage.



中文翻译:

用于锂离子电池的机械和热稳定性微孔共聚物隔膜

下一代多功能隔膜可以增强锂离子电池的储能、动力和安全性能,但必须易于制造并与现有的卷对卷制造相结合。本研究提出了一种使用紫外引发聚合诱导相分离 (PIPS) 轻松制备这些隔膜的策略,其中微孔聚合物隔膜直接由组成单体和碳酸亚乙酯 (EC) 致孔剂制成。这使得具有广泛的组成设计空间成为可能,因为具有特定化学功能的共聚单体可以很容易地结合到 PIPS 前体混合物中。在此,1,4-丁二醇二丙烯酸酯(BDDA)与聚(乙二醇)二丙烯酸酯(PEGDA)共聚以增加光聚合中的丙烯酸酯转化率并改善机械性能。-1 ) 已准备好。PEGDA 的加入对于将弹性模量增加到 > 345 MPa 是必不可少的,这是通过卷对卷制造进行电池组装所必需的。所制备的所有隔膜均显示能够实现锂金属/LiNi 0.5 Mn 0.3 Co 0.2 O 2半电池的可逆循环100次循环。与显示在 160 °C 时熔化并在高温下收缩高达 29.8% 的传统聚烯烃隔膜不同,PIPS 隔膜具有出色的、增强安全性的热机械性能,不会发生相变或热收缩。

更新日期:2022-06-12
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