All Graphene Lithium Ion Capacitor with High-Energy-Power Density Performance

作者：Gu Xiaoyu; Hong Ye; Ai Guo^*; Wang Chaoyang^*; Mao Wenfeng^*

来源：Acta Chimica Sinica, 2018, 76(8): 644-648.

DOI：10.6023/A18020081

• three-dimensional graphene
• hierarchical porous structure
• lithium ion capacitor
• prelithiation

Taking advantage of the extended specific surface area and high conductivity, graphene has been widely subjected to extensive investigations by many research groups. Herein, three-dimensional graphene (3DG) were prepared by a facile and scalable ion-exchange method, which exhibited a porous structure with a specific surface area of 2400 m(2)/g and pore volume of 2.0 cm(3)/g. In a typical sysnthesis, two procedures played an important role in preparing the novel characteristics of 3DG: First, metal ions were used as the catalysis to graphitize the ion-exchange resin. Second, an KOH activation step at low temperatures (800) was applied on the exchange resin to produce a hierarchical porous structure of 3DG materials. The method of catalysis, chemical activation and heating treatment can form a unique interconnected structure and also effectively prevent graphene nanosheets from aggregating. Various structural and morphology analyses have been characterized by X-ray powder diffraction, Raman, Scanning electron microscope and Transmission electron microscope. Additionally, the enhanced specific surface area can improve capacitor performance of 3DG, which exhibited a high specific capacitance of 250 F/g when measured in a three-electrode system (KOH aqueous solution) and 120 F/g in asymmetric supercapacitor (TEMABF(4)/PC organic electrolytes). Furthermore, the as-prepared 3DG were successfully employed as both cathode and anode active materials for lithium ion capacitors (3DG-LIC) with high energy density (105 Wh/kg) because the potential window of 3DG-LIC extended from 2.5 to 4.0 V compared to traditional supercapacitor (SC) by prelithiation of anode. The performance and operating mechanism of 3DG-LIC were further studied by cyclic voltammetry, gals anostatic charge/discharge, and electrochemical impedance spectroscopy. The similar chemistry and microstructure maximizes the capacity and rate performance of cathode and anode, which indicates that the 3DG-LIC can be a promising candidate for high-energy power storage system and would have a wide application in other electrochemical applications.

• 出版日期2018-8-15
• 单位华南理工大学