Research on the LiODFB Electrolyte’s Electrochemical Performance and Its Compatibility with LTO Electrode

doi:10.3724/SP.J.1077.2013.12316

Abstract

Abstract:

1 mol/L LiODFB (LiPF₆) EC+DMC+EMC (1:1:1 (wt%)) electrolyte’s thermal stability and corrosivity to the aluminum foil were tested by the electrochemical workstation. Cyclic voltammogram, electrochemical impedance spectroscopy rate and cycle performances of LTO/Li battery were measured. The compatibility between LiFePO₄/LTO electrode and electrolyte was studied. Results show that at room temperature and 60℃, the stability of LiODFB electrolyte and its corrosivity to the aluminum foil are superior to that of LiPF₆ electrolyte. LTO/Li cells with either LiODFB or LiPF₆ for electrolyte have simple REDOX peak, and their first charge-discharge curves have stable charge-discharge platform. The difference battery performance between LiODFB and LiPF₆ with LiFePO₄/LTO as electrode at 0.5C and 1C rates is not significant at room temperature. LiODFB battery exhibits better cycle performance than LiPF₆ battery at room temperature and especially at 60℃.

Key words: lithium di?uoro(oxalato)borate, lithium titanate, electrochemical performance, lithium battery

CLC Number:

TM911

ZHOU Hong-Ming,LIU Fu-Rong, LI Jian, FANG Zhen-Qi, LI Yan-Fen, ZHU Yu-Hua. Research on the LiODFB Electrolyte’s Electrochemical Performance and Its Compatibility with LTO Electrode[J]. Journal of Inorganic Materials, 2013, 28(5): 507-514.

Figures/Tables 10

Fig. 1 I-E curves of electrolytes

Fig. 2 I-E curves of aluminum foil in electrolytes

Fig. 3 CV curves of LTO/Li cells with LiODFB electrolyte at different temperatures

Fig. 4 Initial charge-discharge curves of LiFePO4/LTO cells with LiODFB electrolyte at different temperatures

Fig. 5 Cycle performance of LiFePO4/LTO cells with LiODFB electrolyte at different rates

Fig. 6 Cycle performance of LiFePO4/LTO batteries with LiODFB electrolyte at different temperatures

Fig. 7 Electrochemical impedance spectra of LTO/Li cell with LiODFB electrolyte before and after cycling

Fig. 8 Equivalent circuit of AC impedance for electrolyte

Table 1 Electrochemical impedance of LiODFB or LiPF6 at different temperatures

Situation	R_L(LiODFB)/Ω	R_L(LiBF6)/Ω	R_ct(LiODFB)/Ω	R_ct(LiBF6)/Ω
25℃ before cycling	10.80	24.9	341.9	278.70
25℃ after cycling	15.30	45.2	367.9	348.70
60℃ before cycling	6.58	4.6	34.2	43.06
60℃ after cycling	9.80	27.9	57.2	64.50

Fig. 9 SEM images of LiFePO4 electrode from LiFePO4/LTO cells before and after cycling

References 22

[1]	Zhang S S. An unique lithium salt for the improved electrolyte of Li-ion battery. Electrochemistry Communications, 2006, 8(9): 1423-1428.
[2]	GAO Hong-quan, ZHANG Zhi-an, LAI Yan-qing. Structure characterization and electrochemical properties of new lithium salt LiODFB for electrolyte of lithium ion batteries. J. Cent. South Univ. Technol., 2008, 15(23): 830-834.
[3]	邓凌峰, 陈洪. 锂离子电池电解质LiBC2O4F2的合成与电化学性能. 电源技术, 2010, 34(3): 237-240.
[4]	Zhang S S. Electrochemical study of the formation of a solid electrolyte interface on graphite in a LiBC2O4F2-based electrolyte. Journal of Power Sources, 2007, 163(7): 713-718.
[5]	付茂华. 磷酸铁锂电池用高低温电解液的研究. 长沙: 中南大学硕士论文, 2010.
[6]	FU M H, HUANG K L, LIU S Q, et al. Lithium diﬂuoro(oxalato) borate/ethylene carbonate + propylene carbonate + ethyl (methyl) carbonate electrolyte for LiMn2O4 cathode. Journal of Power Sources, 2010, 195(11): 862-866.
[7]	Zhang S S, Xu K, Jow T R. Understanding formation of solid electrolyte interface film on LiMn2O4 electrode. Journal of the Electrochemical Society, 2002, 149(12): 1521-1526.
[8]	Liu J, Chen Z H, Sara B, et al. Lithium diﬂuoro(oxalato)borate as a functional additive for lithium-ion batteries. Electrochemistry Communications, 2007, 9(3): 475-479.
[9]	Ohzuku T, Ueda A, Yamamoto N. Zero-strain insertion material of Li[Li1/3Ti5/3]O4 for rechargeable lithium cells. J. Electrochem Soc., 1995, 142(5):1431-1435.
[10]	Kanamura K, Umegak T, Naito H, et al. Structural and electrochemical characteristics of Li4／3Ti5／3O4 as an anode material for rechargeable lithium batteries. Journal of Applied Electrochemistry, 2001, 31(14): 73-78.
[11]	CHENG Liang, LIU Hai-jing, ZHANG Jing-jun. Nanosized Li4Ti5O12 prepared by molten salt method as an electrode material for hybrid electrochemical super capacitors. Journal of The Electrochemical Society, 2006, 153(8): A1472-A1477.
[12]	HUANG S H, WEN Z Y, ZHU X J. Preparation and electrochemical performance of Ag doped Li4Ti5O12. Electrochemistry Communications, 2004, 6(11): 1093-1097.
[13]	Young Ho Rho, Kiyoshi Kanamura, Minori Fujisaki, et al. Preparation of Li4Ti5O12 and LiCoO2 thin film electrodes from precursors obtained by Sol-Gel method. Solid State Ionics, 2002, 151(22): 151-157.
[14]	Jiang C H, Ichihara M, Honma I, et al. Effect of particle dispersion on high rate performance of nano-sized Li4Ti5O12 anode. Electrochimica Acta, 2007, 52(12): 6470-6475.
[15]	Nakahara K, Nakajima R, Matsushima T, et al. Preparation of particulate Li4Ti5O12 having excellent characteristics as an electrode active material for power storage cells. J. Power Sources, 2003, 117(23): 131-136.
[16]	李凡群. LiODFB基电解液及其与LiFePO4-AC/AG-AC超级电容电池电极材料的相容性研究. 长沙: 中南大学硕士论文, 2009.
[17]	付茂华, 黄可龙, 刘素琴, 等(Fu Mao-Hua, et al). 二氟二草酸硼酸锂对LiFePO4/石墨电池高温性能的影响. 物理化学学报(Acta Phys. Chim. Sinica), 2009, 25(10): 1985-1990.
[18]	LI J, XIE K X, LAI Y Q, et al. Lithium oxalyldiﬂuoroborate/ carbonate electrolytes for LiFePO4/artiﬁcial graphite lithium-ion cells. Journal of Power Source, 2010, 195(16): 5344-5350.
[19]	陈凤凤. 锂离子电池中新型电解质的合成与表征. 南京: 南京师范大学硕士论文, 2010.
[20]	郑洪河. 锂离子电池电解质. 北京: 化学工业出版社, 2007: 26-29.
[21]	HUI Yang, GUO Rong, Philip N, et al. Thermal stability of LiPF6 salt and Li-ion battery electrolytes containing LiPF6. Journal of Power Sources, 2006, 161(15): 573-579.
[22]	Ohzuku T, Ueda A, Yamamot N, et al. Factor affecting the capacity retention of lithium-ion cells. Solid State Ionics, 1994, 69(24): 201-211.