K2.25Ni0.55Co0.37Fe(CN)6 nanoparticle connected by cross-linked carbon nanotubes conductive skeletons for high-performance energy storage

Abstract

Prussian Blue (PB) coordination compound is a well-known ideal candidate for energy storage due to its tunable open framework structure. Especially transition metal hexacyanoferrate displays excellent performance in supercapacitor. In this paper, a facile one-step co-precipitation synthesis method is developed to prepare hybrid K2.25Ni0.55Co0.37Fe(CN)6/CNTs composite, aiming at increasing the electric conductivity of electrode material by introducing carbon nanotube conductive skeleton to the Cobale-Nickel hexacyanoferrate hybrid nanoparticles. The TEM image shows that K2.25Ni0.55Co0.37Fe(CN)6 presents nanoparticles with a diameter about 20nm, which are connected along the surface of carbon nanotube. Such special structure could facilitate the electric transportation between each nanoscale K2.25Ni0.55Co0.37Fe(CN)6 particle, efficiently improving the utilization of active material. Considering the intrinsic abundant channels for ions insertion/extraction of nanoparticles and good conductivity of carbon nanotubes, our creative electrode is expected to display fantastic supercapacitor performance. The electrochemical data demonstrate that the K2.25Ni0.55Co0.37Fe(CN)6/CNTs electrode exhibits a high specific capacitance of 600Fg−1 at 0.2Ag−1and excellent rate performance of 90.4% when the current density ranged from 0.2Ag−1 to 5Ag−1. Furthermore, the K2.25Ni0.55Co0.37Fe(CN)6/CNTs composite achieves decent cycling stability with maintaining 94% of its initial specific capacitance after 2000discharge/charge cycles. The excellent energy storage property offers a great promise as supercapacitor materials.