Potentiodynamic deposition of composition influenced Co1−xNix LDHs thin film electrode for redox supercapacitors

https://doi.org/10.1016/j.ijhydene.2013.01.047Get rights and content

Abstract

Current paper comprises the electrodeposition of nanostructured porous Co1−xNix layered double hydroxide (Co1−xNix LDHs) thin films on to stainless steel substrate by a potentiodynamic mode. The compositional impacts on the various properties of Co1−xNix LDHs are examined via structural, morphological, surface wettability and electrochemical studies. The nanocrystalline Co1−xNix LDHs thin films possess varying porous, nanoflake like morphology and superhydrophilic behavior by the composition influence. Electrochemical studies demonstrate the supercapacitive performance of Co1−xNix LDHs thin film electrodes. The maximal specific capacitance for Co1−xNix LDHs electrode is found to be ∼1213 F g−1 for composition Co0.66Ni0.34 LDH in 2 M KOH electrolyte at 5 mV s−1 scan rate owing specific energy of 104 Whkg−1, specific power of 1.44 kW kg−1 with ∼94% of coulomb efficiency and stability of electrode retained to 77% after 10,000th cycle. The high capacitance retention proposes the deposited Co1−xNix LDHs thin film as promising contender for supercapacitor applications.

Highlights

► Co1−xNix layered double hydroxides by potentiodynamical mode. ► The Co1−xNix LDHs thin film electrodes as redox supercapacitor with specific capacitance ∼ 1213 F g−1. ► Highly electrochemical cyclic stability retained 77% after 10,000th cycle. ► Co0.66Ni0.34 LDHs showed specific energy = 104 W h kg−1, specific power = 1.44 kW kg−1 and coulomb efficiency ∼94%.

Introduction

Supercapacitors are the mostly studied electrochemical devices in the energy storage research field. Supercapacitors have very high specific power and higher charge/discharge rate than the existing secondary batteries [1], [2], [3]. They arouse wide concern by researchers, but their low specific energy restricts them to be used as power sources alone. Nanomaterials are rapidly developing and have been widely used in lots of fields because of their outstanding advantages in science and technology. Currently, many more materials are potential contenders as electrode materials for supercapacitor function. Such as activated carbon (AC), carbon aerogels, carbon nanotubes as electric double layer capacitors (EDLCs) electrode; transition metal oxides/hydroxides, conducting polymers as pseudocapacitive (redox) electrodes, etc [4], [5], [6]. Kang et al. recently reported exceed charge/discharge current of the ion-exchange based electrode material [6], [7]. Therefore, further breakthroughs in materials are essential. In this regard, the nanostructured layered double hydroxide LDH) materials open up a new important avenue in the advancement of the science and technology [8]. Nanomaterials bring us the advantages of higher electrode/electrolyte contact area, short path lengths for cation transport, high power performance and new reactions, which are not possible with bulk materials [9], [10], [11]. The existing nano-size electrode materials have higher specific mass capacity in the process of charge/discharge than the general micro size electrode material. It has been reported in recent years that some nanostructured electrode materials obtain good charge/discharge capacity [13], [14].

Current advances of metal hydroxides, especially layered double hydroxides with very high specific capacitances have regenerated great interest in such materials. Mainly, Co(OH)2 and Ni(OH)2 are strong contenders as an electrode materials having very high specific capacitances due to their layered structures with large interlayer spacing and characteristic redox reaction. Recently Gupta et al. prepared CoxNi1−x LDHs by the potentiostatically and reported a maximum specific capacitance of 2104 F g−1 however; in this case the potential window is only 0.4 V [11]. Also Hu et al. synthesized CoxNi1−x LDHs by a chemical co-precipitation route using polyethylene glycol and obtained maximal specific capacitance of 1809 F g−1 in 6 M KOH electrolyte [12].

In this work, for the first time we reported the synthesis of Co1−xNix LDHs thin films as supercapacitor electrode material via potentiodynamic mode (cyclic voltammetry) in aqueous media. The effect of composition variation of Co and Ni on structural, morphological, wettability and supercapacitive properties of Co1−xNix LDHs thin films along with their stability and charging–discharging characteristics are performed. This work will investigate the correlations between its chemical composition and structural, morphological, surface wettability and electrochemical capacitive characteristics in detail, and confirm that the Co1−xNix LDHs are strong supercapacitor electrode material. The results reported here will help to modify and engineer LDH materials accordingly the energy application.

Section snippets

Experimental

Analytical grade chemicals Co(NO3)2·6H2O, Ni(NO3)2·6H2O and research grade stainless steel (SS, grade 304) were used for the deposition of Co1−xNix LDHs thin films. The stainless steel substrate was polished with emery paper to a rough finish, washed with double distilled water and make free of abrasive particles and then air dried. For the deposition of Co1−xNix LDHs films; aqueous baths of 0.1 M solutions of Co(NO3)2, Ni(NO3)2 at pH ∼6 were used. The suitable composition of Co1−xNix LDHs was

Film formation

Fig. 1 shows voltammograms recorded for 0.1 M solutions of Ni(NO3)2, Co(NO3)2 and Co(NO3)2 + Ni(NO3)2 at bath compositions 0.0:1.0, 1.0:0.0 and 0.5:0.5 on stainless steel substrate, respectively. The possible redox reactions are given below. During electrodeposition from aqueous solution of Co(NO3)2:Ni(NO3)2 at negative potentials, nitrate ions can be reduced (E0 = −200 mV/SCE) on the cathodic surface to produce hydroxide ions. The generation of OH at the cathode raises the local pH, as follow

Conclusions

The nanostructured porous Co1−xNix layered double hydroxides (Co1−xNix LDHs), which exhibit both Co(OH)2 and Ni(OH)2, have been successfully deposited in the thin film form by potentiodynamic mode owing randomly oriented nano-flakes like morphology and superhydrophilic characteristics. The increase of Ni content (x = 0, 0.34, 0.46, 0.59, 0.76 and 1) in Co1−xNix LDHs affects emerging surface morphological aspect. Maximal specific capacitance for Co1−xNix LDHs electrode was found ∼1213 F g−1,

Acknowledgment

Authors are grateful to the Council for Scientific and Industrial Research (CSIR), New Delhi (INDIA) for financial support through the scheme. No. 03(1165)/10/EMR-II.

References (37)

  • L. Bing et al.

    Cyclic voltammetric studies of stabilized α-nickel hydroxide electrode

    J Power Sources

    (1999)
  • A.H. Zimmerman

    Technological implications in studies of nickel electrode performance and degradation

    J Power Sources

    (1984)
  • X.M. Ni et al.

    Interconnected β-Ni(OH)2 sheets and their morphology-retained transformation into mesostructured Ni

    Solid State Commun

    (2006)
  • L.T. Lam et al.

    Development of ultra-battery for hybrid-electric vehicle applications

    J Power Sources

    (2006)
  • J.R. Miller

    Electrochemical capacitor thermal management issues at high-rate cycling

    Electrochim Acta

    (2006)
  • E. Frackowiak et al.

    Carbon materials for the electrochemical storage of energy in capacitors

    Carbon

    (2001)
  • U.M. Patil et al.

    Chemically deposited nanocrystalline NiO thin films for supercapacitor application

    Appl Surf Sci

    (2008)
  • F.Y. Cheng et al.

    High-power alkaline Zn–MnO2 batteries using c-MnO2 nanowires/nanotubes and electrolytic zinc powder

    Adv Mater

    (2005)
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