芳纶-固态离子导体复合隔膜的制备与性能

Study on preparation and performance of poly(m-phenylene isophthalamide)/solid-state ionic conductor composite membrane

采用非溶剂诱导相分离法(NIPS)制备了具有高热稳定性和良好电解液浸润性的芳纶-固态离子导体复合隔膜(PMIA-LATP-PEO)。在复合材料体系中,聚间苯二甲酰间苯二胺(PMIA)是绝缘和高温稳定性的基体,具有NASICON型骨架结构的磷酸钛铝锂(LATP)均匀分布于基体之中,用于提高隔膜的离子电导率,聚环氧乙烷(PEO)在制膜过程中起到调节孔径的作用,并可提升与锂金属的界面相容性。采用扫描电子显微镜(SEM)及能谱分析(EDS)观察隔膜形貌及元素分布,DSC和TGA及热收缩方法表征了其热稳定性,电化学技术测试了其离子电导率、锂离子迁移数等电化学性能,并测试了隔膜在LiFePO_(4)||Li电池中的循环性能和倍率性能。研究结果表明:PMIA-LATP-PEO复合膜具有丰富的立体孔隙结构,在200℃高温下保持尺寸形态稳定,绝缘性可靠。该隔膜的锂离子电导率达2.07×10^(-3) S/cm(25℃),锂离子迁移数(t_(Li+))为0.75。此外,PMIA-PEO-LATP复合膜对锂稳定性好,在Li||Li对称电池中以0.5 mA/cm2恒电流稳定循环大于1000 h,并可以抑制锂枝晶生长,复合膜在LiFePO_(4)||Li电池中表现出良好的循环稳定性。

The nonsolvent induced phase separation(NIPS)method was used to create Poly(m-phenylene isophthalamide)/solid-state ionic conductor composite membranes(PMIA-LATPPEO)with high thermal stability and excellent electrolyte wettability.Poly(m-phenylene isophthalamide)(PMIA)serves as an insulation and high-temperature stability matrix in the composite system.Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)with a sodium super ion conductor(NASICON)structure is a solid-state ionic conductor evenly distributed in the membrane for the enhancement of the ionic conductivity of the composite membrane.Poly(ethylene oxide)(PEO)plays a role in adjusting the pore size in the process of membrane preparation and can improve the interface stability between membranes with lithium metal.The morphology and element distribution of membranes were studied using scanning electron microscopy(SEM)and energy spectrum analysis(EDS).Differential scanning calorimetry(DSC),thermogravimetric analysis(TGA),and thermal shrinkage methods were used to characterize the thermal stability of the membranes.The electrochemical properties of the membranes,such as ionic conductivity and lithium-ion transference number,were measured using electrochemical technology.The cycling performance and rate performance of the composite membranes were measured in the LiFePO_(4)||Li cells.PMIA-LATP-PEO membrane has a dense pore structure and reliable insulation and maintains a stable dimensional shape at 200℃.The lithium ionic conductivity is 2.07×10^(-3) S/cm(25℃)for electrochemical performance,and the transference number of lithium-ion is 0.75.Furthermore,the PMIA-PEO-LATP membrane is resistant to lithium metal.In Li||Li symmetrical cells,the PMIA-PEO-LATP membrane can run stably for over 1000 h at 0.5 mA/cm2.Furthermore,the PMIA-PEO-LATP membrane can inhibit the growth of lithium dendrites,allowing LiFePO_(4)||Li cells to show superior cycling stability.