材料期刊网

作为电池的重要组成部分，电解质在很大程度上影响着锂电池的安全性、温度适应性、充放电性能和循环寿命。研究合成了二氟草酸硼酸锂（ LiODFB）?N?甲基?N?甲氧基乙基吡咯烷双（三氟磺酰亚胺）（ Pyr1，2O 1 TFSI）／亚硫酸酯电解质，展现出良好的离子传导性、电极相容性和宽工作温度范围，其中LiODFB?Pyr1，2 O 1 TFSI／DMS电解质体系的电导率和锂离子迁移数分别为8?163×10－3 S·cm－1，0?28。首次将离子液体基电解质体系的应用温度范围拓展到－40℃，使Li／MCMB电池和Li／ LiFe?PO4电池在－40～60℃的工作温度范围内均表现出理想的电化学性能。以Li[ N（ SO2 CF3）2]（ LiTFSI）作为锂盐，将三（乙二醇）二甲醚（TEGDME）作为共溶剂，结合离子液体Pyr1，2O1TFSI，制备系列Li／S电池电解质。含LiTFSI?（70wt％）Pyr1，2O1TFSI／（30wt％）TEGDME电解质的Li／S电池表现出优秀的循环性能和倍率性能，在0?1 C充放电倍率下，首周循环周期放电比容量1212?8 mAh·g－1，循环100周后仍然维持在693?5 mAh·g－1。在1 C放电倍率下，循环100周放电比容量约为827?3 mAh· g－1，库伦效率达到99％以上。同时，该电解质还具有良好的高温性能，电池在80℃仍然可以正常工作，放电容量达1005?3 mAh·g－1。在总结相关研究工作的基础上，从离子液体／有机共溶剂电解质体系出发，首次半定量对离子液体／共溶剂体系和电化学基本性质间的构效关系进行了深入分析，对未来面向不同应用方向的锂二次电池电解质体系的设计合成具有一定的理论意义和参考价值。

As a key component of a battery, electrolyte has a potent influence on its safety, operating temperature, charge/discharge performance and cycle life. Novel electrolytes were prepared based on ( N?methoxyethyl?N?methylpyrrolidin?ium bis ( trifluoromethanesulfonyl)?imide, Pyr1,2O1 TFSI) and sulfites as co?solvents with lithium difluoro ( oxalate) borate ( LiODFB) as lithium salt, exhibiting good ion transport, electrode compatibility and wide operating temperature range. The conductivity and Li+transference number of the LiODFB?Pyr1,2O1TFSI/ DMS electrolyte was 8?163×10-3 S·cm-1 and 0?28, respectively. The Li/MCMB and Li/ LiFePO4 cells containing this electrolyte had good cycle performance and normal charge curve in the temperature of-40 ℃ to 60 ℃. Moreover, a series of electrolytes for Li/S battery were prepared based on (Pyr1,2O1TFSI) with tris(ethylene glycol) dimethyl ether (TEGDME) as co?solvents in different proportions. LiTFSI was used as lithium salt. Li/S cells with LiTFSI?(70wt%)Pyr1,2O1TFSI/ (30wt%)TEGDME electrolyte exhibited excellent cycle and rate performance, whose capacity was 1 212?8 mAh·g-1 in the first cycle and 693?5 mAh·g-1 after 100 cycles at cur?rent density of 0?1 C, and 827?3 mAh·g-1 with the coulombic efficiency of above 99% at current density of 1 C. In addi?tion, the cells showed good high temperature performance which could operate at 80 ℃ with the initial cycle capacity of 1 005?3 mAh · g-1 . A summary of representative electrolyte systems of ionic liquid with organic co?solvent for lithium battery and the corresponding characteristics and properties based on the investigations above and the previous studies are illustrated for the first time. It might be proposed to offer a useful starting point to design the mixed electrolyte in lithium batteries.