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

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 K 2.25 Ni 0.55 Co 0.37 Fe(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 K 2.25 Ni 0.55 Co 0.37 Fe(CN) 6 presents nanoparticles with a diameter about 20 nm, which are connected along the surface of carbon nanotube. Such special structure could facilitate the electric transportation between each nanoscale K 2.25 Ni 0.55 Co 0.37 Fe(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 K 2.25 Ni 0.55 Co 0.37 Fe(CN) 6 /CNTs electrode exhibits a high specific capacitance of 600 F g −1 at 0.2 A g −1 and excellent rate performance of 90.4% when the current density ranged from 0.2 A g −1 to 5 A g −1 . Furthermore, the K 2.25 Ni 0.55 Co 0.37 Fe(CN) 6 /CNTs composite achieves decent cycling stability with maintaining 94% of its initial specific capacitance after 2000 discharge/charge cycles. The excellent energy storage property offers a great promise as supercapacitor materials. [ABSTRACT FROM AUTHOR]