Self-assembled bimetallic cobalt–manganese metal–organic framework as a highly efficient, robust electrode for asymmetric supercapacitors

Abstract

To obtain highly efficient supercapacitors with extraordinary capacitance, energy density, and cycle life, the design and development of new electrode materials having numerous active sites on the surface are essential. Not only the kind of material but also the surface morphology and microporous structure of the electrode plays an important role in the electrochemical performance of the supercapacitor. In the present work, a bimetallic Co/Mn-metal–organic framework (MOF) has been prepared using a simple hydrothermal method for supercapacitor application. This bimetallic MOF mainly produces a synergistic effect by connecting two kinds of metal ions through an organic ligand. The resulting bimetallic Co/Mn MOF electrode shows a high specific capacitance of 1176.59 F g−1 (2.76 F cm−2) at a current density of 3 mA cm−2 and excellent cycling stability over 5000 cycles. The constructed Co/Mn MOF//AC hybrid supercapacitor exhibits a specific energy of 57.2 Wh kg−1 at a specific power of 2000 W kg−1 and excellent capacity retention of 93.51% over 5000 cycles. These outstanding results are compared with those of similar devices in the literature, thus revealing that our approach is a desirable direction for future research on high-performance energy storage devices as well as hybrid supercapacitors.