Evaluation of a Redox-Active Cu-MOF and Co-MOF as Electrode Materials for Battery-Supercapacitor-Type Hybrid Energy Storage Devices

Abstract

The emerging supercapattery imparts optimum electrochemical performance by synchronizing the admirable power density and cyclic stability of supercapacitors with the high energy density characteristic of batteries. The strong bonds of a metal center with an organic linker give rise to a unique group of porous materials known as metal-organic frameworks (MOFs). Here, we state the synthesis and electrochemical analyzation of a copper-MOF and cobalt-MOF. The initial specific capacity revealed in the three-electrode assembly for the Cu-MOF and Co-MOF is 451 and 103 C g-1 at 3 mV s-1, respectively. Owing to the favorable characteristics of the Cu-MOF, a supercapattery device is fabricated as Cu-MOF//activated carbon. The device exhibits energy and power densities of 41 Wh g-1 and 2400 W kg-1, respectively, with a reversible capacity retention of 92% and coulombic efficiency of 99%. Moreover, to elucidate the capacitive and diffusive contributions of the battery-supercapacitor, Dunn’s model is adapted. The favorable properties of the Cu-MOF electrode as a battery-grade material may be adapted for future energy storage applications.