Silica‐Mediated Formation of Nickel Sulfide Nanosheets on CNT Films for Versatile Energy Storage

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2019-04, Vol.15 (15), p.e1805064-n/a
• Main Authors: Lu, Pengyi, Wang, Xiaowei, Wen, Lei, Jiang, Xiaotong, Guo, Wenlei, Wang, Lei, Yan, Xiao, Hou, Feng, Liang, Ji, Cheng, Hui‐Ming, Dou, Shi Xue
• Format: Article
• Language: English
• Subjects: Batteries; Carbon nanotubes; Energy storage; lithium‐ion storage; metal sulfide nanosheets; Nanosheets; Nanostructure; Nanotechnology; Nickel sulfide; Redox reactions; Silicon dioxide; Silicon oxides; Sodium; sodium‐ion storage; Structural integrity; supercapacitors
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201805064

An effective, nondestructive, and universal strategy to homogeneously modify freestanding carbon nanotube (CNT) films with various active species is essential to achieve functional electrodes for flexible electrochemical energy storage, which is challenging and has attracted considerable research interest. In this work, a generalizable concept, to utilize silicon oxide as the intermediate to uniformly decorate various metal sulfide nanostructures throughout CNT films is reported. Taking nickel sulfide nanosheet/CNT (NS/CNT) films, in which the NS nanosheets are homogeneously attached on the intact few‐walled CNTs, as an example, the sheet‐like NS provides sufficient active sites for redox reactions and the CNT network acts as an efficient electron highway, maintaining the structural integrity of the composite and also buffering volume changes. These merits enable NS/CNT films to meet the requirements of versatile energy storage applications. When used for supercapacitors, a high specific capacitance (2699.7 F g−1/10 A g−1), outstanding rate performance at extremely high rates (1527 F g−1/250 A g−1), remarkable cycling stability, and excellent flexibility can be achieved, among the best performance so far. Moreover, it also delivers excellent performance in the storage of Li and Na ions, meaning it is also potentially suitable for Li/Na ion batteries. Flexible, freestanding, and continuous nickel sulfide nanosheet/CNT (NS/CNT) films are fabricated through a silica‐mediated conversion process. The NS nanosheets with controllable phases and compositions are homogeneously and intimately attached on highly graphitized and few‐walled CNTs. The NS/CNT can be directly used as a multifunctional electrode and achieves extraordinary performance for both supercapacitor application and Li/Na ion storage.