离子液体复合体系改性PEO制备新型固态聚合物电解质

Ionicliquid composite system modified PEO to prepare a new solid polymer electrolyte

固态聚合物电解质(SPE)因其独特的安全性能受到越来越多的关注。在此,以新型聚离子液体(PIL)/离子液体(IL)共混改性聚环氧乙烷(PEO),制备了一种PEO基高性能固态聚合物电解质。利用X射线衍射(XRD)、热重(TG)方法探究了样品的晶体结构和热稳定性,研究结果表明,PIL/IL的引入,显著降低了结晶度,同时表现出较高的热稳定性(320℃)。通过电化学阻抗(EIS)、线性扫描伏安(LSV)等方法研究了固态聚合物电解质的电化学性能,研究结果表明,结晶度的降低显著地提高了离子电导率(2.27×10^(-4) S·cm^(-1),40℃)和锂离子迁移数(0.3,40℃),同时由于咪唑环C(2)位上的质子氢被烷基取代,提高了电化学窗口(4.8 V)。通过组装LiFePO_(4)/Li全电池进行充放电测试,发现其稳定放电容量高达150 mAh·g^(-1),100次循环后放电容量保持不变,库伦效率保持在99%以上,展现出较高的容量和循环稳定性。

Solid polymer electrolyte(SPE)has attracted more and more attention due to its unique safety performance.Here,we prepared a PEO-based high-performance solid-state polymer electrolyte with a novel poly(ionic liquid)(PIL)/ionic liquid(IL)blend-modified poly(ethylene oxide).The crystal structure and thermal stability of the samples were investigated by X-ray diffraction(XRD)and thermogravimetric(TG)methods.The results showed that the introduction of PIL/IL significantly reduced the crystallinity and exhibited high thermal stability(320℃).The electrochemical properties of solid polymer electrolytes were investigated by electrochemical impedance(EIS),linear sweep voltammetry(LSV).The results showed that the reduction of crystallinity significantly improved the ionic conductivity(2.27×10^(-4) S/cm,40°C)and lithium-ion transference number(0.3,40°C).At the same time,the electrochemical window is improved due to the substitution of the proton hydrogen on the C(2)position of the imidazole ring by an alkyl group.By assembling the LiFePO_(4)/Li cell for charge and discharge tests,it was found that the stable discharge capacity was as high as 150 mAh/g.The discharge capacity remained unchanged after 100 cycles,and the Coulomb efficiency remained above 99%,showing high capacity and cycle stability.