LiODFB electrolyte's compatibility with LiNi_(0.5)Mn_(1.5)O_4 high-voltage cathode material was studied by cyclic voltammetry, charge-discharge test and AC impedance. The results show that at 25 and 60 °C, th...LiODFB electrolyte's compatibility with LiNi_(0.5)Mn_(1.5)O_4 high-voltage cathode material was studied by cyclic voltammetry, charge-discharge test and AC impedance. The results show that at 25 and 60 °C, the LiODFB-based electrolyte has better electrochemical stability than LiPF_6. AC impedance plots show that the LiODFB battery has a lower charge-transfer resistance than LiPF_6 battery at 60 °C, which indicates that LiODFB battery has excellent cycling performance at high temperature. At 25 and 60 °C, the LiNi_(0.5)Mn_(1.5)O_4/Li half cells with Li ODFB or LiPF_6 as electrolyte all have simple redox peak, showing that each of them has an excellent reversibility. LiODFB battery has better cycle performance than LiPF_6 battery at 25 °C and 60 °C. At 25 °C, their 0.5C initial discharge specific capacities are 126.3 and 131.6 m A·h/g, and their capacity retention ratios of the 100 th cycle are 97.1% and 94.7%, respectively. At 60 °C, their 0.5C initial discharge specific capacities are 132.6 and 129.1 m A·h/g, and their capacity retention ratios of the 100 th cycle are 94.1% and 81.7%, respectively.展开更多
Lithium difluoro(axalato)borate (LiODFB) was synthesized in dimethyl carbonate (DMC) solvent and purified by the method of solventing-out crystallization. The structure characterization of the purified LiODFB was perf...Lithium difluoro(axalato)borate (LiODFB) was synthesized in dimethyl carbonate (DMC) solvent and purified by the method of solventing-out crystallization. The structure characterization of the purified LiODFB was performed by Fourier transform infrared (FTIR) spectrometry and nuclear magnetic resonance (NMR) spectrometry. The electrochemical properties of the cells using 1 mol/L LiPF6 and 1 mol/L LiODFB in ethylene carbonate (EC)/DMC were investigated, respectively. The results indicate that LiODFB can be reduced at about 1.5 V and form a robust protective solid electrolyte interface (SEI) film on the graphite surface in the first cycle. The graphite/LiNi1/3Mn1/3Co1/3O2 cells with LiODFB-based electrolyte have very good capacity retention at 55 ℃, and show very good rate capability at 0.5C and 1C charge/discharge rate. Therefore, as a new salt, LiODFB is a most promising alternative lithium salt to replace LiPF6 for lithium ion battery electrolytes in the future.展开更多
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
基金Project(K1403375-11)supported by Science and Technology Planning Project of Changsha,China
文摘LiODFB electrolyte's compatibility with LiNi_(0.5)Mn_(1.5)O_4 high-voltage cathode material was studied by cyclic voltammetry, charge-discharge test and AC impedance. The results show that at 25 and 60 °C, the LiODFB-based electrolyte has better electrochemical stability than LiPF_6. AC impedance plots show that the LiODFB battery has a lower charge-transfer resistance than LiPF_6 battery at 60 °C, which indicates that LiODFB battery has excellent cycling performance at high temperature. At 25 and 60 °C, the LiNi_(0.5)Mn_(1.5)O_4/Li half cells with Li ODFB or LiPF_6 as electrolyte all have simple redox peak, showing that each of them has an excellent reversibility. LiODFB battery has better cycle performance than LiPF_6 battery at 25 °C and 60 °C. At 25 °C, their 0.5C initial discharge specific capacities are 126.3 and 131.6 m A·h/g, and their capacity retention ratios of the 100 th cycle are 97.1% and 94.7%, respectively. At 60 °C, their 0.5C initial discharge specific capacities are 132.6 and 129.1 m A·h/g, and their capacity retention ratios of the 100 th cycle are 94.1% and 81.7%, respectively.
基金Project(2007BAE12B01) supported by the National Key Technology Research and Development Program of ChinaProject(20803095) supported by the National Natural Science Foundation of China
文摘Lithium difluoro(axalato)borate (LiODFB) was synthesized in dimethyl carbonate (DMC) solvent and purified by the method of solventing-out crystallization. The structure characterization of the purified LiODFB was performed by Fourier transform infrared (FTIR) spectrometry and nuclear magnetic resonance (NMR) spectrometry. The electrochemical properties of the cells using 1 mol/L LiPF6 and 1 mol/L LiODFB in ethylene carbonate (EC)/DMC were investigated, respectively. The results indicate that LiODFB can be reduced at about 1.5 V and form a robust protective solid electrolyte interface (SEI) film on the graphite surface in the first cycle. The graphite/LiNi1/3Mn1/3Co1/3O2 cells with LiODFB-based electrolyte have very good capacity retention at 55 ℃, and show very good rate capability at 0.5C and 1C charge/discharge rate. Therefore, as a new salt, LiODFB is a most promising alternative lithium salt to replace LiPF6 for lithium ion battery electrolytes in the future.
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the financial supports from the National Natural Science Foundation of China (Nos. 21766017, 51962019)the Major Science and Technology Projects of Gansu Province, China (No. 18ZD2FA012)+1 种基金the Chinese Academy of Sciences “Western Light” Young Scholars ProjectLanzhou University of Technology Hongliu First-class Discipline Construction Program, China
