Improving the performance of all-solid-state supercapacitors by modifying ionic liquid gel electrolytes with graphene nanosheets prepared by arc-discharge

• Published in: Chinese chemical letters Vol. 25; no. 6; pp. 859 - 864
• Main Authors: Shi, Min-Jie, Kou, Sheng-Zhong, Shen, Bao-Shou, Lang, Jun-Wei, Yang, Zhi, Yan, Xing-Bin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2014
• Subjects: All-solid-state supercapacitor; Arc discharge; Electrolyte; Graphene; Ionic liquid gel; 全固态; 凝胶电解质; 凝胶聚合物电解质; 电化学性能; 电弧放电; 离子液体; 纳米薄片; 超级电容器; Ionic liquid gel; All-solid-state supercapacitor; Electrolyte; Graphene; Arc discharge
• ISSN: 1001-8417; 1878-5964
• DOI: 10.1016/j.cclet.2014.04.010

Ionic liquid gel polymers have widely been used as the electrolytes in all-solid-state supercapacitors, but they suffer from low ionic conductivity and poor electrochemical performance. Arc discharge is a fast, low-cost and scalable method to prepare multi-layered graphene nanosheets, and as-made graphene nanosheets （denoted as ad-GNSs） with few defects, high electrical conductivity and high thermal stability should be favorable conductive additive materials. Here, a novel ionic liquid gel polymer electrolyte based on an ionic liquid （EM1MNTF2） and an copolymer （P（VDF-HFP）） was modified by the addition of ad-GNSs as an ionic conducting promoter. This modified gel electrolyte shows excellent thermal stability up to 400 ℃ and a wide electrochemical window of 3 V. An all-solid-state supercapacitor based on commercial activated carbon was fabricated using this modified ionic liquid gel polymer electrolyte, which shows obviously improved electrochemical behaviors compared with those of the corresponding all-solid-state supercapacitor using pure ionic liquid gel polymer electrolyte. Specially, smaller internal resistance, higher specific capacitance, better rate performance and cycling stability are achieved. These results indicate that the ionic liquid gel polymers modified by ad-GNSs would be promising and suitable gel electrolytes for high performance all-solid-state electrochemical devices.