
磺酰亚胺锂型固态聚合物电解质的合成及其电化学性能
梁金兰, 吴道欢, 邹海凤, 陈卓, 庄金亮, 程琥
磺酰亚胺锂型固态聚合物电解质的合成及其电化学性能
Synthesis and electrochemical performance of lithium sulfonimide solid polymer electrolyte
分别以4-氟苯磺酰氯和4-氰基苯磺酰氯为原料,通过磺酰化和离子交换分别合成氟代和氰基取代的磺酰亚胺锂(LiFBTFSI和LiCBTFSI),进一步通过溶液浇铸法制备两种PEO基聚合物电解质(PEO20-LiFBTFSI和PEO20-LiCBTFSI),并对其微观形貌、热稳定性及电化学性能进行表征。结果表明:在60 ℃、EO/Li+=20时,两种固态电解质的离子电导率均达到10-4 S/cm,电化学稳定窗口均大于5 V,与磷酸铁锂组装的电池均具有较高的首次放电比容量(0.1 C,≈150 mAh·g-1)。相比于氟代PEO20-LiFBTFSI固态电解质,含氰基的PEO20-LiCBTFSI固态电解质具有更优异的电化学稳定性和界面相容性,循环50次后,电池的放电比容量为137.4 mAh·g-1,容量保持率为93.0%。此外,含氰基的PEO20-LiCBTFSI固态电解质与锂金属具有良好的电化学稳定性,组装的锂对称电池在电流密度0.1 mA/cm2下稳定运行500 h而不发生短路。
Fluorinated and cyanosubstituted lithium sulfonimide (LiFBTFSI and LiCBTFSI) are synthesized from 4-fluorobenzene sulfonyl chloride and 4-cyanobenzene sulfonyl chloride by sulfonylation and ion exchange, respectively. Two PEO based polymer electrolytes (PEO20-LiFBTFSI and PEO20-LiCBTFSI) are prepared by solution casting, and their micromorphology, thermal stability and electrochemical properties are characterized. The results show that at 60 ℃ and EO/Li+=20, the ionic conductivity of the two solid electrolyte reaches 10-4 S/cm, the electrochemical stability window is greater than 5 V, and the battery assembled with lithium iron phosphate has a high initial discharge capacity (0.1 C, ≈150 mAh·g-1). Compared with the fluorine PEO20-LiFBTFSI solid electrolyte, the cyan-containing PEO20-LiCBTFSI solid electrolyte has better electrochemical stability and interface compatibility. After 50 cycles, the specific discharge capacity of the battery is 137.4 mAh·g-1, and the capacity retention rate is 93.0%. In addition, the cyano-containing PEO20-LiCBTFSI solid electrolyte has good electrochemical stability with lithium metal, and the assembled lithium symmetric battery operates stably at a current density of 0.1 mA/cm2 for 500 h without short circuit.
lithium-ion battery / polymer electrolyte / lithium salt / polyoxyethylene
TQ152
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