Developing Binder‐Free Electrode Based on Metal‐Organic Frameworks and Graphene Hydrogel for Electrochemical Energy Storage

Abstract

As a kind of metal‐organic framework (MOF), Prussian blue (PB) and its analogues (PBAs) with open channel structure and adjustable composition have been widely used in alkali metal batteries. However, using PB and PBAs as electrode materials for supercapacitors directly is very rare, and most of them are prepared as derivatives for supercapacitor. Herein, a hybrid configuration of nickel–cobalt hexacyanoferrate (NiCoHCF)/graphene hydrogels (denoted as NCFG) is successfully prepared via a facile coprecipitation method combined with a hydrothermal process. The highly interconnected integrated 3D network structure not only compensates the conductivity of NiCoHCF, but can also be directly applied as both anode and cathode for a symmetric supercapacitor without adding conductive agent and binder, due to excellent mechanical robustness. The as‐prepared NCFG nanocomposite delivers a high specific capacitance of 321 F g−1 at 1 A g−1 in 1 m Na2SO4 aqueous electrolyte. Moreover, the assembled NCFG//NCFG symmetric supercapacitor exhibits a wide voltage window of 2.0 V with a high energy density of 41.6 Wh kg−1 at a power density of 1 kW kg−1. This work has reference significance for directly using MOFs as electrode materials for supercapacitors.