The microstructures and thermal stability of separators are critical for the safety and performance of lithium-ion batteries; however, it is still challenging to fabricate advanced separators simultaneously achieving uniform and high-throughput interconnected microporous structures with high thermal stability. Here, based on a soluble polyimide (PI) with high thermal stability, we report a microfluid-on-microfluid phase separation strategy (MF-PS) to address the above challenge. Compared to the traditional non-solvent induced phase separation by immersion, the MF-PS strategy can achieve more controlled porous structures with sponge-like open channels at submicron scale. The high surface polarity of the PI-separator also exhibited good wettability with liquid electrolytes, and a high electrolyte uptake (182 wt%) for achieving a high ion-conductivity. It also showed much superior thermal stability as compared to PP separator. Finally, due to the unique porous structures, the PI-separator by MF-PS strategy successfully delivered a discharge capacity of 161.9 mA h g for LiFePO electrode, and very stable cycling performance. All these results indicates that the PI-separator by MF-PS may find significant applications in safe and high-performance batteries.

中文翻译：

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微流体对微流体相分离策略制造用于锂离子电池的高通量多孔聚酰亚胺隔膜


隔膜的微观结构和热稳定性对于锂离子电池的安全性和性能至关重要；然而，制造先进的隔膜同时实现均匀、高通量、具有高热稳定性的互连微孔结构仍然具有挑战性。在这里，基于具有高热稳定性的可溶性聚酰亚胺（PI），我们报告了一种微流体对微流体相分离策略（MF-PS）来解决上述挑战。与传统的浸入式非溶剂诱导相分离相比，MF-PS策略可以在亚微米尺度上实现具有海绵状开放通道的更可控的多孔结构。 PI 隔膜的高表面极性还表现出良好的液体电解质润湿性，以及高电解质吸收率 (182 wt%)，可实现高离子电导率。与 PP 隔膜相比，它还表现出优异的热稳定性。最后，由于独特的多孔结构，采用 MF-PS 策略的 PI 分离器成功为 LiFePO 电极提供了 161.9 mA h g-1 的放电容量和非常稳定的循环性能。所有这些结果表明，MF-PS 的 PI 分离器可以在安全和高性能电池中找到重要的应用。