Building 3D structures of vanadium pentoxide nanosheets and application as electrodes in supercapacitors

Zhu, Jixin and Cao, Liujun and Wu, Yingsi and Gong, Yongji and Liu, Zheng and Hoster, Harry E. and Zhang, Yunhuai and Zhang, Shengtao and Yang, Shubin and Yan, Qingyu and Ajayan, Pulickel M. and Vajtai, Robert (2013) Building 3D structures of vanadium pentoxide nanosheets and application as electrodes in supercapacitors. Nano Letters, 13 (11). pp. 5408-5413. ISSN 1530-6984

Abstract

Various two-dimensional (2D) materials have recently attracted great attention owing to their unique properties and wide application potential in electronics, catalysis, energy storage, and conversion. However, large-scale production of ultrathin sheets and functional nanosheets remains a scientific and engineering challenge. Here we demonstrate an efficient approach for large-scale production of V2O5 nanosheets having a thickness of 4 nm and utilization as building blocks for constructing 3D architectures via a freeze-drying process. The resulting highly flexible V2O5 structures possess a surface area of 133 m(2) g(-1), ultrathin walls, and multilevel pores. Such unique features are favorable for providing easy access of the electrolyte to the structure when they are used as a supercapacitor electrode, and they also provide a large electroactive surface that advantageous in energy storage applications. As a consequence, a high specific capacitance of 451 F g(-1) is achieved in a neutral aqueous Na2SO4 electrolyte as the 3D architectures are utilized for energy storage. Remarkably, the capacitance retention after 4000 cycles is more than 90%, and the energy density is up to 107 W.h.kg(-1) at a high power density of 9.4 kW kg(-1).