隔膜是可充放锂离子电池的重要组成部分之一，它起到隔离电池正负极以防止电池发生短路和提供微孔结构以传导锂离子的作用。隔膜性能的优劣对电池的性能如循环性和安全性等具有重要的影响作用。

本论文主要是从提高电池的安全性出发，基于聚酰亚胺（PI）材料，采用高压静电纺丝方法制备出具有良好的多孔结构、电化学稳定、机械性能良好且耐高温的PI无纺布隔膜。并对其物理和电化学性能进行了一系列表征，最后将隔膜组装电池进行充放电和循环性能的测试。主要包括如下几个方面的内容：

（1）用高压静电纺丝法制备的PI纳米纤维无纺布隔膜具有高孔隙率、好的透气率和良好的电解液浸润性以及拉伸强度等特性；PI无纺布隔膜在150℃的高温下能长时间保持尺寸稳定状态；PI无纺布隔膜在电压范围为2.5 V~5.0 V（vs Li⁺/Li）内能保持电化学稳定状态；PI无纺布隔膜浸泡电解液（1 M LiPF₆/EC/DMC）后具有高的离子电导率（1.88 mS cm^-1，25℃）；用PI无纺布隔膜组装的电池在倍率性能上要优于用商业化Celgard PP隔膜组装的电池。

（2）用同轴静电纺丝法制备的PI@PVDF-HFP同轴纳米纤维无纺布隔膜亦具有高孔隙率、好的透气率、良好的电解液浸润性以及电化学稳定性等特性；PI@PVDF-HFP无纺布隔膜具有较高的拉伸强度，在干态时拉伸强度为53 MPa，在湿态时拉伸强度为31 MPa；PI@PVDF-HFP无纺布隔膜在150℃的高温下能长时间保持尺寸稳定状态；PI@PVDF-HFP无纺布隔膜浸泡电解液（1 M LiPF₆/EC/DMC）后具有高的离子电导率（1.68 mS cm^-1，25℃）；用PI@PVDF-HFP无纺布隔膜组装的电池不仅在倍率性能方面要优于用商业化Celgard 2500隔膜组装的电池，而且在长循环性能上也要好于后者。

（3）PI无纺布隔膜浸泡电解液（0.5 M LiBOB/PC）后在120℃的高温能下在电压范围为2.5 V~4.5 V（vs Li⁺/Li）内保持电化学稳定状态；PI无纺布隔膜浸泡电解液（0.5 M LiBOB/PC）后在120℃的高温下具有非常高的离子电导率（1.73 m Scm^-1），用PI无纺布隔膜组装的电池在120℃的高温下测试发现具有非常好的充放电和长循环性能，电池经过50次循环后，放电比容量保存率依然高达82%。

As one of the key components in rechargeable lithium-ion batteries, the separator plays a role in insulating the cathode and anode to avoid short circuits and also providing micropore structure for rapid transport of the ion carriers. Moreover, the separator dominates some battery performance such as rate capability, cycleability and safety characteristics.

In this dissertation, polyimide-based non-woven separators were fabricated via an electrospinning process. The physical and electrochemical properties of the nanofibrous non-woven separators were investigated and their battery performance in the cells were also disscussed.

Firstly, the PI nanofibrous non-woven separators obtained by an electrospinning process exhibited outstanding properties such as high porosity, low Gurley value, sufficient electrolyte wettability and high mechanical strength. The PI non-woven separators could maintain dimensional stability at 150℃ and keep electrochemical stability at the voltage range from 2.5 V to 5.0 V (vs Li⁺/Li). The PI non-woven separators soaked in the electrolyte (1M LiPF₆/EC/DMC) showed high ionic conductivity (1.88 mS cm^-1) at ambient temperature. The lithium-ion batteries using the PI non-woven separators delivered better rate capability than the batteries using the commerical polypropylene separators.

Secondly, The PI@PVDF-HFP nanofibrous non-woven separators explored via coaxial electrospinning also displayed high porosity, low Gurley value, excellent electrolyte wettability and electrocheical stability. The PI@PVDF-HFP non-woven separators had superior tensile strength, 53 MPa in the dry state and 31 MPa in the wet state. The PI@PVDF-HFP non-woven separators could maintain dimensional stability at 150℃. The PI@PVDF-HFP non-woven separators soaked in the electrolyte (1M LiPF₆/EC/DMC) showed high ionic conductivity (1.68 mS cm^-1) at ambient temperature. The cells using the PI@PVDF-HFP non-woven separators were manifested to perform not only better rate capability but also superior cycle capability retention than the cells using the commerical polypropylene separators.

Thirdly, the PI non-woven separators remained electrochemical stability at the voltage range from 2.5 V to 4.5 V at high temperature of 120℃. The PI non-woven separators soaked in 0.5M LiBOB/PC electrolyte delivered considerable ionic conductivity（1.73 m Scm^-1）at 120℃. The cells employing the PI non-woven separators displayed satisfactory cycle capability at 120℃, which retained 82% discharge capacity after 50 cycles at 120℃.