"Water in salt/ionic liquid" electrolyte for 2.8 V aqueous lithium-ion capacitor

Qingyun Dou; Yue Wang; Aiping Wang; Meng Ye; Ruilin Hou; Yulan Lu; Lijun Su; Siqi Shi; Hongzhang Zhang; Xingbin Yan

doi:10.1016/j.scib.2020.07.009

"Water in salt/ionic liquid" electrolyte for 2.8 V aqueous lithium-ion capacitor

Sci Bull (Beijing). 2020 Nov 15;65(21):1812-1822. doi: 10.1016/j.scib.2020.07.009. Epub 2020 Jul 7.

Authors

Qingyun Dou¹, Yue Wang², Aiping Wang³, Meng Ye⁴, Ruilin Hou¹, Yulan Lu⁵, Lijun Su¹, Siqi Shi³, Hongzhang Zhang⁶, Xingbin Yan⁷

Affiliations

¹ Laboratory of Clean Energy Chemistry and Materials, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
² Laboratory of Clean Energy Chemistry and Materials, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China.
³ School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China; Materials Genome Institute, Shanghai University, Shanghai 200444, China.
⁴ Laboratory of Clean Energy Chemistry and Materials, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, China.
⁵ Laboratory of Clean Energy Chemistry and Materials, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
⁶ Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China; Dalian National Laboratory for Clean Energy, Dalian 116000, China; Division of Energy Storage, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
⁷ Laboratory of Clean Energy Chemistry and Materials, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China; Dalian National Laboratory for Clean Energy, Dalian 116000, China. Electronic address: xbyan@licp.cas.cn.

PMID: 36659121
DOI: 10.1016/j.scib.2020.07.009

Abstract

Development of high-voltage electrolytes with non-flammability is significantly important for future energy storage devices. Aqueous electrolytes are inherently non-flammable, easy to handle, and their electrochemical stability windows (ESWs) can be considerably expanded by increasing electrolyte concentrations. However, further breakthroughs of their ESWs encounter bottlenecks because of the limited salt solubility, leading to that most of the high-energy anode materials can hardly function reversibly in aqueous electrolytes. Here, by introducing a non-flammable ionic liquid as co-solvent in a lithium salt/water system, we develop a "water in salt/ionic liquid" (WiSIL) electrolyte with extremely low water content. In such WiSIL electrolyte, commercial niobium pentoxide (Nb₂O₅) material can operate at a low potential (-1.6 V versus Ag/AgCl) and contribute its full capacity. Consequently, the resultant Nb₂O₅-based aqueous lithium-ion capacitor is able to operate at a high voltage of 2.8 V along with long cycling stability over 3000 cycles, and displays comparable energy and power performance (51.9 Wh kg^-1 at 0.37 kW kg^-1 and 16.4 Wh kg^-1 at 4.9 kW kg^-1) to those using non-aqueous electrolytes but with improved safety performance and manufacturing efficiency.

Keywords: Aqueous electrolyte; Electrochemical stability window; Lithium-ion capacitor; Niobium pentoxide.