Molecular Origin of Electric Double-Layer Capacitance at Multilayer Graphene Edges

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• 作者：Huachao Yang ; Xiaoliang Zhang ; Jinyuan Yang ; Zheng BoMing Hu ; Jianhua Yan ; Kefa Cen
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2017
• 出版时间：January 5, 2017
• 年：2017
• 卷：8
• 期：1
• 页码：153-160
• 全文大小：571K
• ISSN：1948-7185

文摘

Multilayer graphenes have been widely used as active materials for electric double-layer capacitors (EDLCs), where their numerous edges are demonstrated to play a crucial role in charge storage. In this work, the interfacial structure and capacitive behaviors of multilayer graphene edges with representative interlayer spacing are studied via molecular dynamics (MD) simulations. Compared with planar graphite surfaces, edges can achieve a 2-fold increase in the specific capacitance at a wider interlayer spacing of ∼5.0 Å. Unusually, the molecular origins for achieved charge storage are predominantly attributed to the structural evolutions of solvents occurring in the double layer, going beyond the traditional views of regulating the capacitance by ion adsorption/separation. Specifically, diverse ionic distributions exhibit similar screening ability and EDLC thickness, while water molecules can counterbalance the interfacial electric fields more effectively at edge site. The as-obtained findings will be instructive in designing graphene-based EDLCs for advanced capacitive performances.