大倍率高耐热聚醚酰亚胺-聚偏氟乙烯芯壳纳米纤维锂离子电池隔膜

以高耐热、高强度的聚醚酰亚胺（PEI）为芯层材料，以电解液亲和性和界面稳定性优良的聚偏氟乙烯（PVDF）为壳层材料，构建了一种具有同轴结构的大倍率、高耐热PEI-PVDF纳米纤维锂离子电池隔膜。通过SEM、TEM、TGA、电化学工作站、电池测试系统对PEI-PVDF同轴隔膜的微观形貌和性能进行测试与表征。结果表明:PEI-PVDF同轴纤维具有清晰的芯壳结构，与商业隔膜相比，PEI-PVDF同轴隔膜具有优异的热稳定性，在180℃下处理2 h，尺寸稳定并未发生热收缩；吸液率达到520%；电化学稳定性优异，电化学窗口达到5.0 V；离子电导率达到2.3 mS·cm-1；采用PEI-PVDF隔膜组装的锂离子电池在8 C的放电流下放电比容量仍能达到107 mAh·g-1，再回到0.2 C时恢复到原始比容量的95.4%，且电池在1 C电流下循环100次后容量保持率高达92.5%，PEI-PVDF隔膜表现出的大倍率、高耐热的特点说明该纤维膜是一种高功率、高安全的锂离子电池隔膜。 

A high rate and heat-resistant polyether imide-polyvinylidene fluoride core-shell nanofiber separator for lithium-ion battery

A new type nanofiber separator with coaxial structure for lithium ion battery was constructed through electrospinning method. Polyether imide (PEI) was adopted as the core layer material due to its high heat-resistance and high strength, and polyvinylidene fluoride (PVDF) with excellent electrolyte affinity and interfacial stability was adopted as the shell layer material. The structure and performances of PEI-PVDF coaxial separator were investigated by SEM, TEM, TGA, electrochemical workstation, and battery test system. The results show that PEI-PVDF coaxial fiber has a clear core-shell structure. Compared with the commercial separator, it has excellent thermal stability and does not shrink after treated at 180℃ for 2 h. The liquid electrolyte absorption rate also increases greatly, and reaches up to 520%. The electrochemical stability window is up to 5.0 V. The ionic conductivity is 2.3 mS·cm^-1. The lithium ion battery assembled with PEI-PVDF coaxial separator still show the specific discharge capacity of 107 mAh·g^-1 at discharge current density of 8 C. In the recovery at 0.2 C rate, the specific capacity retain 95.4% of its original specific capacity. The coulombic efficiency of the batteries is 92.5% after 100 cycles of charge and discharge. The characteristics of the high rate and high heat resistance of the PEI-PVDF separator show that it is a kind of high power, high safety separator for lithium ion battery.