Role of Additives in Electrochemical Deposition of Ternary Metal Oxide Microspheres for Supercapacitor Applications.

Avijit Biswal,Manickam Minakshi Sundaram,Achyuta Nanda Acharya,Subhashree Mohapatra,Nibedita Swain,Zhong-Tao Jiang,Bankim Chandra Tripathy,Prasanna Kumar Panda

doi:10.1021/acsomega.9b03657

Avijit Biswal, Manickam Minakshi Sundaram + Show 6 more

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https://doi.org/10.1021/acsomega.9b03657

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Abstract

A simple two-step approach has been employed to synthesize a cobalt–nickel–copper ternary metal oxide, involving electrochemical precipitation/deposition followed by calcination. The ternary metal hydroxide gets precipitated/deposited from a nitrate bath at the cathode in the catholyte chamber of a two-compartment diaphragm cell at room temperature having a pH ≈ 3. The microstructure of the ternary hydroxides was modified in situ by two different surfactants such as cetyltrimethylammonium bromide and dodecyltrimethylammonium bromide in the bath aiming for enhanced storage performance in the electrochemical devices. The effect of the surfactant produces a transition from microspheres to nanosheets, and the effect of micelle concentration produces nanospheres at a higher ion concentration. The ternary hydroxides were calcined at 300 °C to obtain the desired ternary mixed oxide materials as the electrode for hybrid supercapacitors. X-ray diffraction analysis confirmed the formation of the ternary metal oxide product. The scanning electron microscopy images associated with energy-dispersive analysis suggest the formation of a nanostructured porous composite. Ternary metal oxide in the absence and presence of a surfactant served as the cathode and activated carbon served as the anode for supercapacitor application. DTAB-added metal oxide showed 95.1% capacitance retention after 1000 cycles, achieving 188 F/g at a current density of 0.1 A/g, and thereafter stable until 5000 cycles, inferring that more transition metals in the oxide along with suitable surfactants at an appropriate micellar concentration may be better for redox reactions and achieving higher electrical conductivity and smaller charge transfer resistance. The role of various metal cations and surfactants as additives in the electrolytic bath has been discussed.

Highlights

In the ever-increasing trend of industrialization, the prevalent demands and applications of electrochemical energy storage devices such as batteries and supercapacitors are unavoidable
Amid the two categories of supercapacitors such as electrical double-layer capacitors (EDLCs) and the faradaic redox reaction pseudocapacitors, the latter one draws much attention as it offers high capacitance and high energy density than the former.[3−9] Asymmetric supercapacitors fall under “faradaic redox pseudocapacitors” which are in high demand because of their wide electrochemical window with high specific capacitance possessing a battery-type behavior, and these key features make them seemly candidates to fulfill the needs of the incipient energy storage applications in the market.[10,11]
The synergistic effect consists of high capacity attributed by Ni leading to improved active site density, conductivity, and roughness, while the presence of Co leads to increased electronic conductivity, and the role of Zn is attributed to good electrical conductivity that results in the overall improvement of the capacitance in the energy storage device.[5,7]

Summary

INTRODUCTION

In the ever-increasing trend of industrialization, the prevalent demands and applications of electrochemical energy storage devices such as batteries and supercapacitors are unavoidable. The synergistic effect consists of high capacity attributed by Ni leading to improved active site density, conductivity, and roughness, while the presence of Co leads to increased electronic conductivity, and the role of Zn is attributed to good electrical conductivity that results in the overall improvement of the capacitance in the energy storage device.[5,7] TOs offer abundant structural defects due to the presence of multiphase metal oxides by several metal ions leading to a stable and improved cycle life.[18] On the other hand, in the field of electrodeposition, it is well known that the nucleation and growth of the crystal structures of the internal active oxide materials can be altered by various structure-directing agents/ surfactants such as cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC),[33−35] tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide,[36] tetradecyltrimethylammonium bromide,[37] sodium lauryl sulphate,[38] and sodium dodecyl sulfate.[38] it is imperative to use organic additives as surfactants in the electrolytic bath to improve the structural and morphological properties of the oxide deposits. It has been shown in this work that the obtained specific capacitance value (188 F/g at 0.1 A/g) for the modified ternary metal oxide exceeds the previously reported values for ternary metal oxides,[31,32] which is attributed to the role of additives and CuO

EXPERIMENTAL SECTION

RESULTS AND DISCUSSION

CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES