Effect of dopant concentration and ambient temperature on the pseudo-capacitance behavior of novel copper doped bismuth layered double hydroxide

Abstract

Supercapacitors made up of 2D heterostructures materials have revolutionized the industry of energy harvesting devices because of their distinct physical and chemical properties, superior cyclic stability, better coulombic efficiency, and higher energy density, along with the retention of higher power density. In this study, newly prepared copper bismuth LDH (as an efficient electrode material for supercapacitors), has been synthesized using an environmentally friendly co-precipitation approach. The synthesized material has shown a unique optical characteristic (3.56 eV) band gap which is less than that of bismuth hydroxide (4.06 eV) and copper hydroxide (4.5 eV). Furthermore, the scanning electron microscopy (SEM) confirmed the non-uniform microstructure. The copper-doped bismuth layered double hydroxide (CBL) exhibited battery-type supercapacitor (pseudo capacitor) characteristics as shown by Dunn's Model applied on cyclic voltammetry (CV) results. With an impressive specific capacitance of 205 F g⁻¹ at 1 A g⁻¹, the 2.5% CBL electrode is capable of functioning efficiently throughout a broad operating potential window. The constructed symmetric supercapacitor exhibited exceptional cycling performance (84% retention of capacitance and 94% coulombic efficiency until 4000 cycles). The findings show that symmetric supercapacitors may be designed efficiently for real-life applications, and they are among the best symmetric supercapacitors (energy density 75.5 Wh kg⁻¹ and power density of 918.24 W kg⁻¹) that have been reported so far. Superior conductivity and reduced charge transfer resistance of 2.5% CBL were confirmed by electrochemical impedance spectroscopy (EIS) results. Furthermore, the current study also explored the prominent effect of temperature on electrochemical measurements.