Fabrication of 1.6V hybrid supercapacitor developed using MnSe2/rGO positive electrode and phosphine based covalent organic frameworks as a negative electrode enables superb stability up to 28,000 cycles

Abstract

Recently, bimetallic transition metal selenides have piqued the interest of many researchers for hybrid supercapacitors (HSCs, combination of battery-like and capacitive type electrode in one device) owing to their smaller bandgap as well as higher electrical conductivity. In this study, a simple one-pot hydrothermal method was used to rationally manufacture MnSe2 with nanoflakes structure on rGO sheets (denoted as MnSe2/rGO). The as-prepared MnSe2/rGO composite was first subjected to various routine characterizations for elucidating its microstructure and phase purity. The XRD analysis showed that the samples are highly crystalline. Raman spectroscopy also confirmed the formation of MnSe2/rGO composite by revealing vibrational modes related to the Mn-Se bonding and D, G and 2D bands of rGO. In addition, the detailed XPS investigations further confirmed the co-existence of Se, Mn, and C in the composite. When employed as for HSC electrode, MnSe2/rGO delivered an extraordinary specific capacitance of (326 F g−1/145 C g−1@1.5 A g1), and superb lifespan (99.94% @10,000 cycles), with rapid charge transport reactions during electrochemical activities. Furthermore, a HSC device was constructed using MnSe2/rGO composite, and phosphine based covalent organic frameworks (symbolized as Phos-COF-1) served as positive, and negative electrodes (denoted as MnSe2/rGO//Phos-COF-1 HSC device) could effectively expanded voltage up to 1.6 V with enough energy that could successfully glow a yellow LED with enough brightness with a high specific energy of 16.6 Wh kg−1/800 W kg−1, and still maintained specific energy of 10.0 Wh kg−1 even at a high specific power of 7200 W kg−1.