Acta Phys. -Chim. Sin. ›› 2022, Vol. 38 ›› Issue (2): 2012085.doi: 10.3866/PKU.WHXB202012085

Special Issue: Graphene: Functions and Applications

• REVIEW • Previous Articles     Next Articles

Graphene Film for Supercapacitors: Preparation, Foundational Unit Structure and Surface Regulation

Meihui Jiang1, Lizhi Sheng1,*(), Chao Wang1, Lili Jiang2, Zhuangjun Fan3,*()   

  1. 1 Wood Material Science and Engineering Key Laboratory of Jilin Province, Beihua University, Jilin 132013, Jilin Province, China
    2 School of Materials Science and Engineering, Jilin Institute of Chemical Technology, Jilin 132022, Jilin Province, China
    3 School of Materials Science and Engineering, China University of Petroleum, Qingdao 266580, Shandong Province, China
  • Received:2020-12-30 Accepted:2021-01-18 Published:2021-01-22
  • Contact: Lizhi Sheng,Zhuangjun Fan E-mail:shengli_zhi@126.com;fanzhj666@163.com
  • About author:Email: fanzhj666@163.com (Z.F.)
    Email: shengli_zhi@126.com (L.S.)
  • Supported by:
    the National Natural Science Foundation of China(51902006);the National Natural Science Foundation of China(51702117);the National Natural Science Foundation of China(51672055);the National Natural Science Foundation of China(51972342);the Taishan Scholar Project of Shandong Province(ts20190922);the Key Basic Research Projects of Natural Science Foundation of Shandong Province(ZR2019ZD51);Department of Science and Technology of Jilin Province(20190103034JH);Department of Science and Technology of Jilin Province(20180520014JH);the Young Elite Scientist Sponsorship Program by Jilin Province Science and Technology Association(192009)

Abstract:

With the rapid development of the functional applications of portable and wearable electronic products (such as curved smartphones, smartwatches, laptops, and electronic skins), there is an urgent need to fabricate flexible, lightweight, and highly efficient energy storage devices that can provide sufficient power support. Flexible supercapacitors with high power density, high charging/discharging rates, wide operating temperature ranges, low maintenance consumption, and a long cycling lifespan can be integrated with smart wearable electronic products to provide power support. The conventional preparation method for the electrodes of flexible supercapacitors involves directly coating the active materials on flexible substrates. However, inactive materials such as the substrates and binders occupy a large volume and contribute notably to the weight of flexible electrodes, which is unsuitable for highly integrated flexible electronic devices. Owing to its unique characteristics, including large theoretical specific surface area, high electrical conductivity, excellent mechanical flexibility, good chemical stability, and ease of film processing, graphene has been widely used as an electrode material for flexible supercapacitors. The graphene film is a macrostructure with graphene nanosheets as the main structural units. As opposed to conventional flexible electrodes containing non-electrochemical active components such as collectors, conductive agents, and binders, graphene film electrodes are considered highly promising electrode materials for flexible supercapacitors because of their light weight and robust mechanical properties. However, the inevitable aggregation of graphene during electrode preparation creates ''dead volume'' in the film electrodes, where the electrolyte cannot reach, further limiting the specific capacitance. In this review, we review the recent research on graphene films used for flexible supercapacitors, with emphasis on the assembling methods for graphene films, regulation of the graphene units, and their electrochemical performance. First, simple preparation methods for graphene films are introduced: vacuum-assisted self-assembly, blade coating, pressing aerogel, wet spinning, and interfacial self-assembly. Second, two major strategies for structural control and surface modification of the graphene units are described in detail: (1) structural control can transform the two-dimensional graphene nanosheets into defect graphene, which not only weakens the van der Waals force and ππ bond interactions between the nanosheets, but also leads to the formation of three-dimensional conductive networks and ion transport channels during the assembly process; (2) surface modification, which can suppress the agglomeration of graphene nanosheets by introducing heteroatoms and reactive functional group molecules, while improving their electrical conductivity and wettability, and introducing pseudocapacitance. Finally, the persisting challenges and future development of the commercial applications of graphene films are discussed.

Key words: Graphene film, Supercapacitor, Preparation method, Structural regulation, Surface modification

MSC2000: 

  • O646