High Electroactive Material Loading on a Carbon Nanotube@3D Graphene Aerogel for High‐Performance Flexible All‐Solid‐State Asymmetric Supercapacitors

• Published in: Advanced functional materials Vol. 27; no. 27
• Main Authors: Pan, Zhenghui, Liu, Meinan, Yang, Jie, Qiu, Yongcai, Li, Wanfei, Xu, Yan, Zhang, Xinyi, Zhang, Yuegang
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 19.07.2017
• Subjects: all‐solid‐state asymmetric supercapacitors; Architecture; Asymmetry; Carbon; carbon nanotube@3D graphene aerogels; Carbon nanotubes; Chemical vapor deposition; Electroactive materials; Electrodes; Energy storage; flexible electronic devices; Flux density; Graphene; Gravimetry; Materials science; Nanotubes; Supercapacitors
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201701122

Freestanding carbon‐based hybrids, specifically carbon nanotube@3D graphene (CNTs@3DG) hybrid, are of great interest in electrochemical energy storage. However, the large holes (about 400 µm) in the commonly used 3D graphene foams (3DGF) constitute as high as 90% of the electrode volume, resulting in a very low loading of electroactive materials that is electrically connected to the carbon, which makes it difficult for flexible supercapacitors to achieve high gravimetric and volumetric energy density. Here, a hierarchically porous carbon hybrid is fabricated by growing 1D CNTs on 3D graphene aerogel (CNTs@3DGA) using a facile one‐step chemical vapor deposition process. In this architecture, the 3DGA with ample interconnected micrometer‐sized pores (about 5 µm) dramatically enhances mass loading of electroactive materials comparing with 3DGF. An optimized all‐solid‐state asymmetric supercapacitor (AASC) based on MnO2@CNTs@3DGA and Ppy@CNTs@3DGA electrodes exhibits high volumetric energy density of 3.85 mW h cm−3 and superior long‐term cycle stability with 84.6% retention after 20 000 cycles, which are among the best reported for AASCs with both electrodes made of pseudocapacitive electroactive materials. A simple, scalable, and environmentally friendly method is described for preparing a novel carbon nanotube (CNT)@3D graphene aerogel (3DGA) that acts as an ideal support for high loading of electroactive materials. Lightweight and flexible all‐solid‐state asymmetric supercapacitors are assembled from the MnO2@CNTs@3DGA and polypyrrole@CNTs@3DGA electrodes. The devices realize high areal capacitance and superior mechanical strength and hold great promise for future flexible electronics.