研究四氟硼酸锂(LiBF_4)和二氟草酸硼酸锂(LiODFB)混合锂盐电解液用于磷酸铁锂(LiFePO4)锂离子电池时的低温-20℃性能。探讨电导率与电解液组成、温度的关系;通过循环伏安、充放电、倍率性能及电化学阻抗谱(EIS)测试,比较不同电解液体系...研究四氟硼酸锂(LiBF_4)和二氟草酸硼酸锂(LiODFB)混合锂盐电解液用于磷酸铁锂(LiFePO4)锂离子电池时的低温-20℃性能。探讨电导率与电解液组成、温度的关系;通过循环伏安、充放电、倍率性能及电化学阻抗谱(EIS)测试,比较不同电解液体系中LiFePO_4正极在25℃和-20℃的放电比容量、循环稳定性等。在25℃和-20℃下于2.5~4.2 V充放电,LiFePO_4电极在LiBF_4/Li ODFB基电解液体系中的电化学性能较好:在25℃时以1.0 C倍率充放电,混合盐基电解液电池的首次放电比容量为140 m Ah/g,优于六氟磷酸锂(Li PF6)基电解液的130.5 m Ah/g;-20℃时0.1 C倍率下,首次放电比容量为101.7 m Ah/g,100次循环的容量保持率为86.62%,优于Li PF6基电解液的97.4 m Ah/g和60.57%。展开更多
Lithium oxalyldifluoroborate （LiODFB） was synthesized in dimethyl carbonate solvent and purified by the method of solvent-out crystallization. The structure characterization and thermal stability of LiODFB were perf...Lithium oxalyldifluoroborate （LiODFB） was synthesized in dimethyl carbonate solvent and purified by the method of solvent-out crystallization. The structure characterization and thermal stability of LiODFB were performed by Fourier transform infrared （FTIR） spectrometry, nuclear magnetic resonance （NMR） spectrometry and thermogravimetric analyzer （TGA）. LiODFB was exposed to 50% humid air at 25 ℃for different time, then dried at 80 ℃ for 12 h, and the electrochemical properties of the cells using 1 mol/L dried LiODFB in ethylene carbonate -I- dimethyl carbonate ＋ ethyl（methyl）carbonate were investigated. The results showed that, pure crystallization LiODFB was obtained; it had good thermal stability with a thermal decomposition temperature of 248 ℃; when it was exposed to humid air, it was firstly converted into LiODFB.H20; with increasing exposure time, more and stronger impurity peaks in the X-ray diffraction （XRD） patterns of LiODFB were observed, and both the discharge specific capacity and the capacity retention decreased gradually.展开更多
文摘研究四氟硼酸锂(LiBF_4)和二氟草酸硼酸锂(LiODFB)混合锂盐电解液用于磷酸铁锂(LiFePO4)锂离子电池时的低温-20℃性能。探讨电导率与电解液组成、温度的关系;通过循环伏安、充放电、倍率性能及电化学阻抗谱(EIS)测试,比较不同电解液体系中LiFePO_4正极在25℃和-20℃的放电比容量、循环稳定性等。在25℃和-20℃下于2.5~4.2 V充放电,LiFePO_4电极在LiBF_4/Li ODFB基电解液体系中的电化学性能较好:在25℃时以1.0 C倍率充放电,混合盐基电解液电池的首次放电比容量为140 m Ah/g,优于六氟磷酸锂(Li PF6)基电解液的130.5 m Ah/g;-20℃时0.1 C倍率下,首次放电比容量为101.7 m Ah/g,100次循环的容量保持率为86.62%,优于Li PF6基电解液的97.4 m Ah/g和60.57%。
基金supported by the Science and Technology Project of Changsha, China (No. k1201039-11)
文摘Lithium oxalyldifluoroborate （LiODFB） was synthesized in dimethyl carbonate solvent and purified by the method of solvent-out crystallization. The structure characterization and thermal stability of LiODFB were performed by Fourier transform infrared （FTIR） spectrometry, nuclear magnetic resonance （NMR） spectrometry and thermogravimetric analyzer （TGA）. LiODFB was exposed to 50% humid air at 25 ℃for different time, then dried at 80 ℃ for 12 h, and the electrochemical properties of the cells using 1 mol/L dried LiODFB in ethylene carbonate -I- dimethyl carbonate ＋ ethyl（methyl）carbonate were investigated. The results showed that, pure crystallization LiODFB was obtained; it had good thermal stability with a thermal decomposition temperature of 248 ℃; when it was exposed to humid air, it was firstly converted into LiODFB.H20; with increasing exposure time, more and stronger impurity peaks in the X-ray diffraction （XRD） patterns of LiODFB were observed, and both the discharge specific capacity and the capacity retention decreased gradually.
