摘要
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.
发展不可燃、高电压的电解液对未来的能源存储设备具有重要意义.水系电解液不可燃,易于操作,并且其稳定电压窗口可以通过增大浓度的方式进行拓宽.然而,由于盐在水中溶解度的限制,进一步拓宽水系电解液的电压窗口遇到了瓶颈,导致大多数的高性能负极材料在水系电解液中很难进行可逆的氧化还原反应.本文通过在锂盐和水的体系中引入不可燃的离子液体作为共溶剂,开发了一种含水量极低的"盐/离子液体包水"电解液(WiSIL).使用该WiSIL电解液,商用五氧化二铌(Nb2O5)材料可以在较低电位下工作(-1.6 V vs.Ag/AgCl)并贡献其全部容量.而且,基于Nb2O5的锂离子电容器能够在2.8 V的电压下运行,展现出3000圈的循环稳定性.与相应的有机体系比较,该水系锂离子电容器具有相当的能量和功率密度(0.37 kw kg^-1时51.9 wh kg^-1,4.9 kw kg^-1时16.4 wh kg^-1),但安全性更高、使用更方便.
作者
Qingyun Dou
Yue Wang
Aiping Wang
Meng Ye
Ruilin Hou
Yulan Lu
Lijun Su
Siqi Shi
Hongzhang Zhang
Xingbin Yan
窦青云;王月;王爱平;叶萌;侯瑞林;鲁玉兰;苏利军;施思齐;张洪章;阎兴斌(Laboratory of Clean Energy Chemistry and Materials, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences;Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences;School of Physical Science and Technology, Lanzhou University;School of Materials Science and Engineering, Shanghai University;Materials Genome Institute, Shanghai University;School of Petrochemical Engineering, Lanzhou University of Technology;Division of Energy Storage, Dalian Institute of Chemical Physics, Chinese Academy of Sciences;Dalian National Laboratory for Clean Energy)
基金
supported by the National Natural Science Foundations of China(21573265 and 21673263)
the Zhaoqing Municipal Science and Technology Bureau(2019K038)
the Key Cultivation Projects of the Institute in 13th Five-Year
the Instruments Function Development&Technology Innovation Project of Chinese Academy of Sciences(2020g105)
the Western Young Scholars Foundations of Chinese Academy of Sciences。
