Preparation and properties of polyethylene-SO3Li/poly(vinylidene fluoride-hexafluoropropylene) lithium-ion battery separator
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摘要: 以聚乙烯-乙烯醇的磺化物(EVOH-SO3Li)和聚偏氟乙烯-六氟丙烯(PVDF-HFP)为原料,利用高压静电纺丝技术纺制成高孔隙率、纤维粗细均匀的EVOH-SO3Li/PVDF-HFP复合隔膜材料。利用FTIR、SEM、万能拉伸试验仪、TGA、BMP3电化学工作站和电池检测系统对EVOH-SO3Li/PVDF-HFP隔膜进行测试分析。测试结果表明:EVOH-SO3Li/PVDF-HFP隔膜形成致密的三维网络结构,纤维粗细均匀,孔径均一,EVOH-SO3Li/PVDF-HFP隔膜的孔隙率和吸液率分别为85%和437%;与纯EVOH-SO3Li隔膜相比,EVOH-SO3Li/PVDF-HFP复合隔膜的拉伸强度最大值从2.17 MPa提高至8.33 MPa,起始热分解温度升高至310℃,并表现出良好的电化学性能和电池性能。其中电化学稳定窗口由5.6 V增至5.8 V,界面阻抗由425.51 Ω降低至115.24 Ω,离子电导率由1.592×10-3 S/cm提高至3.102×10-3 S/cm;采用EVOH-SO3Li/PVDF-HFP隔膜组装的锂离子电池在0.5 C放电电流下循环100次后容量保持率为96.65%。
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关键词:
- 锂离子电池隔膜 /
- 聚偏氟乙烯-六氟丙烯 /
- 聚乙烯-乙烯醇的碳化物(EVOH-SO3Li) /
- 高压静电纺丝 /
- 电化学性能
Abstract: High-porosity and uniform-thickness composite separator was prepared by high-pressure electrospinning using polyethylene-vinyl alcohol sulfonate (EVOH-SO3Li) and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) as raw materials. The performance of the EVOH-SO3Li/PVDF-HFP separator was characterized by FTIR, SEM, universal tensile tester, TGA, BMP3 electrochemical workstation and battery testing system. The test results show that the EVOH-SO3Li/PVDF-HFP separator forms a dense three-dimensional network structure with uniform fiber thickness and uniform pore size. The porosity and liquid absorption rate of EVOH-SO3Li/PVDF-HFP separator are 85% and 437%, respectively. Compared with pure EVOH-SO3Li separator, the maximum tensile strength of EVOH-SO3Li/PVDF-HFP composite separator is increased from 2.17 MPa to 8.33 MPa. The initial thermal decomposition temperature also raises to 310℃. The excellent performance of electrochemical and battery is exhibited. The electrochemical stability window is increased from 5.6 V to 5.8 V, the interfacial impedance is reduced from 425.51 Ω to 115.24 Ω, and the ionic conductivity is increased from 1.592×10-3 S/cm to 3.102×10-3 S/cm. Lithium-ion batteries assembled with EVOH-SO3Li/PVDF-HFP separators have a capacity retention rate of 96.65% after 100 cycles at 0.5 C discharge current.
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