为了改善传统电池隔膜不耐高温、吸液性能差等问题,将超细聚对苯二甲酸乙二醇酯(PET)纤维与纤维素纳米纤维(CNF)、微纤化纤维素(MFC)分别按不同比例混合,通过湿法成网和热压工艺制备出湿法非织造共混隔膜,采用冷场发射扫描电子显微镜、傅里叶变换红外光谱仪、差示扫描量热仪等对共混隔膜的微观形貌、化学结构和热性能进行表征,并测试了其力学性能、吸液性能和电化学性能。结果表明:PET/CNF共混隔膜表面光滑且孔径均匀;在150℃、45N的热压条件下,当CNF质量分数为30%时,该隔膜厚度为13μm,机械强度为26.22MPa,对水的浸润面积与速率提升,200℃保温1h无明显形变;将隔膜组装在电池中应用,在电压2.0～3.65V、恒定电流为0.05C时,首次充放电效率为76.6%;恒定电流分别为0.1C和0.2C时,循环60次后充放电效率分别为98.2%与98.9%,接近进口商用陶瓷隔膜。
To address the issues of inadequate thermal stability and poor electrolyte wettability of conventional battery separators,ultrafine polyethylene terephthalate (PET) fibers were blended with cellulose nanofibers (CNF) and microfibrillated cellulose (MFC) at different mass ratios.Wet-laid web formation followed by hot-press consolidation was employed to fabricate wet-laid nonwoven blended separators.The microstructure,chemical structure,and thermal behavior of the resulting separators were characterized by cold field-emission scanning electron microscopy (FE-SEM),Fourier transform infrared spectroscopy(FT-IR),and differential scanning calorimetry (DSC).Their mechanical performance,liquid-uptake capacity,and electrochemical properties were systematically evaluated.The results showed that the PET/CNF blended separator presented a smooth surface morphology and a uniform pore-size distribution.Under hot-pressing conditions of 150℃ and 45N,when the CNF mass fraction was 30%,the separator exhibited a thickness of 13μm and a tensile strength of 26.22MPa,together with enhanced water-wetted area and accelerated wetting rate.Notably,no obvious dimensional deformation was observed after thermal holding at 200℃ for 1h.When assembled into cells and tested within a voltage window of 2.0-3.65V,the separator delivered an initial charge-discharge efficiency of 76.6% at 0.05C.At constant currents of 0.1C and 0.2C,after 60 cycles,the charge-discharge efficiencies reached 98.2% and 98.9%,respectively,approaching those of imported commercial ceramic separators.
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基金资助
国家自然科学基金面上项目(52273059)
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