新型导电盐(三氟甲基磺酰)(三氟乙氧基磺酰)亚胺锂及其非水电解液的制备与性能

制备了一种新型含氟磺酰亚胺锂盐(三氟甲基磺酰)(三氟乙氧基磺酰)亚胺锂{Li(CF₃SO₂)·(CF₃CH₂OSO₂)N], LiTFO-TFSI]}及其与碳酸乙烯酯(EC)/碳酸甲乙酯(EMC)混合溶剂(3∶7, 体积比)组成的非水电解液. 采用核磁共振波谱(NMR)、 红外光谱(IR)、 质谱(MS)、 元素分析(EA)和离子色谱(IC)等手段对合成锂盐LiTFO-TFSI]进行了结构表征及纯度分析. 通过差示量热扫描(DSC)和热重分析(TG)对LiTFO-TFSI]及其电解液1.0 mol/L LiTFO-TFSI]-EC/EMC(3∶ 7)的热学性质进行了表征. 采用交流阻抗(EIS)、 循环伏安(CV)、 计时安培法及扫描电子显微镜(SEM)等对LiTFO-TFSI]/碳酸酯电解液的基础物化和电化学性质进行了表征. 结果表明, LiTFO-TFSI]/碳酸酯电解液具有较好的电化学稳定性; 在4.2 V(vs. Li/Li⁺)以下Al箔不发生腐蚀; 室温下基于LiTFO-TFSI]/碳酸酯电解液的Li/人造石墨和人造石墨/LiCoO₂电池均保持较好的循环性能, 特别是人造石墨/LiCoO₂锂离子电池循环100周后, 其比容量保持率明显高于相应的基于LiPF₆/碳酸酯电解液体系的电池.

Preparation and Properties of Lithium(trifluoromethanesulfonyl)-(trifluoroethoxysulfonyl)imide as Conducting Salt for Nonaqueous Electrolyte Solutions†

A novel lithium salt, lithium(trifluoromethanesulfonyl)(trifluoroethoxysulfonyl)imide{Li(CF₃SO₂)(CF₃CH₂OSO₂)N], LiTFO-TFSI]}, and the corresponding nonaqueous electrolytes of 1.0 mol/L LiTFO-TFSI] in a mixture of ethylene carbonate/ethyl methyl carbonate(EC/EMC, 3∶7, volume ratio) were prepared. The structure, composition and purity of the as-prepared LiTFO-TFSI] were confirmed by nuclear magnetic resonance spectroscopy(NMR), infrared spectroscopy(IR), mass spectrometry(MS), elemental analysis(EA), and ion chromatography(IC). The thermal properties of LiTFO-TFSI] and its nonaqueous electrolytes, 1.0 mol/L LiTFO-TFSI]-EC/EMC(3∶7), were characterized by differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA). The fundamental properties of nonaqueous electrolyte solution of LiTFO-TFSI] were characterized by electrochemical impedance spectroscopy(EIS), cyclic voltammetry(CV), chronoamperometry and scanning electron microscope(SEM). The nonaqueous electrolytes of LiTFO-TFSI] shows excellent electrochemical stability, and does not corrode Al below 4.2 V. Both Li/synthetic graphite and synthetic graphite/LiCoO₂ cells using LiTFO-TFSI] show good cycling performances at room temperature, and the graphite/LiCoO₂ cells using LiTFO-TFSI] shows much better capacity retention after 100 cycles than those using LiPF₆.