The growing demand for enormous transportable power in our modern generation has enthralled more concern in developing high performance advanced energy storage devices like batteries, supercapacitors etc. for practical applications. Among various energy storage devices, supercapacitors have engrossed prevalent attention since last 20 years due to its excellent advantages, such as higher power density than batteries, higher energy density than conventional capacitors, long cycle life, wide range of operating temperature etc. Conversely, regardless of their outstanding industrial success, these supercapacitors are still open to improvements. Energetic research is ongoing on all aspects of supercapacitors, i.e., electrode materials, electrolytes, and cell construction. The major factors off-putting their wider practical application remain cost and safety. Many advance electrode materials with their high performance electrochemical capacitance value have already been reported in several reputed journals but its commercialization is still beyond the horizon. Lots of improvements are yet to be done for practical purpose. Innovative improvements are taking place to address these limitations. Among the oxide materials for application in electrochemical supercapacitors, ruthenium oxide (RuO₂) and iridium oxide (IrO₂) have accomplished much attention. RuO₂ has a high double-layer and pseudo-capacitance (up to ~ 700 F g^-1) and are stable in aqueous acid and alkaline electrolytes. The capacitance sensitively depends on the method of preparation. Tactlessly, disadvantage of RuO₂ such as the high cost of the raw material and toxicity is lagging its great application in supercapacitors device applications. Consequently, in recent years great efforts have been commenced to find new and cheaper materials. Development of advance multifunctional electrode materials with porous, high surface area as well as good electrically interconnection is essential to improve the electrochemical performance of a hybrid supercapacitor. Several metal oxides and hydroxides, for example, those of nickel (Ni), cobalt (Co), Iron (Fe), vanadium (V), and manganese (Mn) are being studied extensively. Among various transition metal oxides, V₂O₅ have already been established to be a promising electrode material for pseudocapacitor compared to carbon-based electrode materials but relatively poor electrical conductivity seems to be a great challenge for their practical energy storage devices application. It has been observed that incorporation of one metal element into other metal oxide can improve the electrical conductivity as well as electrochemical performance.^1-3

In this work, we have synthesized Ni doped V₂O₅ nanocomposite by facile easy hydrothermal process. The overall electrochemical studies along with different spectroscopic analysis have been carried out to investigate the various crucial factors for better improvement. This nanocomposite based asymmetric supercapacitor (ASC) performance has been studied extensively using two electrode set up for practical applications. Activated carbon (AC) based electrode and Ni doped V₂O₅ composite based electrode have been used as negative and positive electrode, respectively. Various electrochemical parameter such as cyclic voltammetry (CV), Galvanostatic charge discharge (GCD), electrochemical impedance (EIS) etc. have been calculated using well known equations.¹ The maximum specific capacitance is obtained 82 Fg^-1 in 1 M Na₂SO₄ gel electrolyte from this fabricated asymmetric supercapacitor device. The two electrode measurement and as fabricated ASC device application are shown in Fig. 1.

The synthesized Ni doped V₂O₅ nanocomposite demonstration excellent asymmetric supercapacitor performance with good stability. The overall studies on the electrochemical properties as well as device performance of this material propose that it can be proved as promising supercapacitor applications in future.

Author A. Ray and S. Das (IFA13-PH-71) wish to thank Department of Science and Technology (D.S.T), INSPIRE, Govt. of India for financial support.

REFERENCES

1. A. Ray et al., Appl. Surf. Sci. 443, 581 (2018).
2. B. E. Conway, J. Electrochem. Soc., 138, 1539 (1991).
3. A. Ray et al., Electrochim. Acta , 266, 404 (2018).