CIESC Journal ›› 2019, Vol. 70 ›› Issue (6): 2334-2342.DOI: 10.11949/j.issn.0438-1157.20181175

• Material science and engineering, nanotechnology • Previous Articles     Next Articles

Ionic liquids as electrolyte additives for high-voltage lithium-ion batteries

Wenlin ZHANG(),Yu HUO,Gongwei LI,Tengfei SUN,Yongqi ZHAO,Chunli LI   

  1. National-Local Joint Engineering Laboratory for Energy Conservation of Chemical Process Integration and Resources Utilization, School of Chemical Engineering, Hebei University of Technology, Tianjin 300130, China
  • Received:2018-10-10 Revised:2019-03-21 Online:2019-06-05 Published:2019-06-05
  • Contact: Wenlin ZHANG

离子液体作为电解液添加剂用于高压锂离子电池

张文林(),霍宇,李功伟,孙腾飞,赵勇琪,李春利   

  1. 河北工业大学化工学院,化工节能过程集成与资源利用国家地方联合工程实验室,天津 300130
  • 通讯作者: 张文林
  • 基金资助:
    河北省高等学校科学技术研究项目(ZD2015118)

Abstract:

The functionalized ionic liquids 1-butyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide (BMIMTFSI) was synthesized as a high-pressure lithium ion battery electrolyte additive for inhibiting the oxidation of organic solvents to enhance carbonic acid. The electrochemical behaviors of LiNi0.5Mn1.5O4/Li batteries and the surface morphology of LiNi0.5Mn1.5O4 electrode were studied by charge-discharge test, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and scanning electron microscopy (SEM). The results show that when 20% (vol) BMIMTFSI is added to carbonate-based electrolyte, the highest discharge capacity of LiNi0.5Mn1.5O4/Li cells is 126.81 mA·h·g-1 at 0.2C rate, and the discharge capacity is 109.36 mA·h·g-1 at high rate of 5C, which is 91.7% higher than that in 1.0 mol·L-1 LiPF6-EC/DMC electrolyte. And the discharge capacity retention rate of LiNi0.5Mn1.5O4/Li cells reaches about 95% after 50 cycles at 0.2C rate, which is nearly 10% higher than that with blank electrolytes. The results of SEM showed that a uniform and compact solid electrolyte interface (SEI) film was attached to the surface of LiNi0.5Mn1.5O4 electrode after adding BMIMTFSI to carbonate-based electrolyte.

Key words: ionic liquids, electrochemistry, oxidation, electrolytes, high voltage, additive, lithium-ion battery

摘要:

合成了功能化离子液体1-丁基-3-甲基咪唑双(三氟甲磺酰)亚胺盐(BMIMTFSI)作为高压锂离子电池电解液添加剂,用于抑制有机溶剂的氧化,以提高碳酸酯类电解液的耐高压性。分别采用充放电测试、电化学交流阻抗(EIS)、循环伏安法(CV)和扫描电子显微镜(SEM)等研究了LiNi0.5Mn1.5O4/Li电池的电化学行为和LiNi0.5Mn1.5O4材料表面形貌。结果表明,当在电解液中添加20% (体积分数)BMIMTFSI时,LiNi0.5Mn1.5O4/Li电池在室温、0.2C下的最高放电比容量是126.81 mA·h·g-1,5C下的放电比容量为109.36 mA·h·g-1,比在1 mol·L-1 LiPF6-EC/DMC电解液中的放电比容量提高了91.7%;且该电池在0.2C下循环50圈后的放电比容量保持率在95%左右,比用碳酸酯类电解液提高了近10%。SEM结果表明,在碳酸酯类电解液中加入BMIMTFSI后,LiNi0.5Mn1.5O4电极表面附着了一层均匀且致密的固态电解质界面(SEI)膜。

关键词: 离子液体, 电化学, 氧化, 电解液, 高压, 添加剂, 锂离子电池

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