International Conference on Current Advancements in Nano Sciences and Engineering

(ICANSE – 2016)

Conventional Chemical Precipitation Route to

Anchoring Ni(OH)2 Nanoparticles For

Supercapacitor Application

P. E. Lokhande

Department of Mechanical Engineering

Vishwakarma Institute of Technology,

Pune, India

E-mail- prasadlokhande2007@gmail.com

Dr. Umesh S. Chavan

Department of Mechanical Engineering Vishwakarma Institute of Technology,

Pune, India

E-mail- umesh.chavan@vit.edu

Abstract— Nanosized β-Ni(OH)2 is being widely used as an

electrode material for supercapacitor because of its high power

density, high specific energy and low toxicity. β-Ni(OH)2 was

successfully synthesized by conventional precipitation method

using ethylenediamine as templting agent. Developed materials

were characterized by using X-ray Diffraction (XRD), Scanning

electron microscope (SEM), Atomic Force Microscopy (AFM),

Fourier Transform Infrared Spectroscopy (FTIR) and Surface

Area Analyzer. Structural characterization suggested the

formation of hexagonal structure of β-Ni(OH)2 and the particle

size was found to be 7.5 nm and 3 nm for conventional and

modified β-Ni(OH)2 respectively. Electrochemical studies were

carried out by using cyclic voltammetric (CV) and

electrochemical impedance spectroscopy (EIS). The observed

specific capacitance for modified β-Ni(OH)2 (222 F/g) was

significantly improved than conventional β-Ni(OH)2(200 F/g) .

Modified β-Ni(OH)2 may be useful for modifying electrodes for

supercapacitor applications.

Keywords— Supercapacitor; Electrochemical double layer

capacitor; pseudocapacitor; Surfactant; β-Ni(OH)2

I. INTRODUCTION (HEADING 1)

Depletion of fossil fuels and the increase in

environmental pollution has created an interest in alternative

energy source development but along this energy storage has

emerged as one of the most essential topics of research.1-3

Due

to high power density, excellent cyclic stability and energy

density, supercapacitor are recognized as an important type of

device for next generation energy storage. It combines

advantages of conventional capacitors and batteries. It is used

as a major power source in hybrid electric vehicle, back up

memory power, emergency door of airplane, portable

electronics, micro devices etc. According to charge storage mechanism supercapacitor divided into two classes, first one is

electrical double layer capacitor (EDLC), in which double

layer capacitance arise from charge separation at the

electrode/electrolyte interface and second one is

pseudocapacitor in which faradaic redox reaction occurs at

solid electrode. This type of pseudocapacitor exhibits much

more capacitance than electrical double layer capacitor

because of its fast and reversible faradic charge storage

mechanism.4

Carbon based materials (activated carbon5,

carbon nanotubes6, carbon aerogels) comes under EDLC while

transition metal oxides, hydroxide (RuO27, MnO2

8, NiO

9,

Ni(OH)29, Co(OH)2

4 etc.) and conducting polymers

(polyaniline10

) comes under pseudocapacitor. The carbon

based material has high power density, high charge/discharge,

cycling stability but it suffers from low specific capacitance.

Transition metal oxides had drawn attention because of high

specific capacitance (RuO27, IrO2

11). Electrochemical

performance depends upon surface area and morphology and

hence if the surface area is higher capacitance will be higher.

In nanosized particles, capacitance is increased as the space

charge layer is in level with grain size, so that application of

external bias of the same magnitude would have an intense

effect on the inter-grain conduction and leading to an increase in electronic conduction

12.

Even though transition metal like RuO2 gives high

specific capacitance it is rare metal and expensive. Ni(OH)2 is

an active transition metal hydroxide and a promising

alternative to the RuO2, due to its low cost, more structural

defects, a larger lattice parameter and higher specific surface

area. The capacitor characteristics of Ni(OH)2 depend upon on

the synthesis and technology parameters, thermal treatment

and storage condition of deposits. In case of nanoparticles

because of their smaller size and large surface to volume ratio,

higher specific capacitance is exhibited. Ni(OH)2 used in

electrode as active material in which the following reversible

reaction occurs

Ni(OH)2 + OH- NiOOH + H2O + e

-

Ni(OH)2 can be prepared in nano size. Dong et al and Jiao et al reported hydrothermal synthesis of nanotubes and

nano rods of Ni(OH)2.13-14

The nano ribbon of Ni(OH)2 with

size 5-25 NM was synthesized and characterized which gave

excellent electrochemical performance.15

Ida et al synthesized

dodecyl sulphate intercalated layered Ni(OH)2.16

Other

research group have also reported about various synthesis

method and characterization of nano sized Ni(OH)2.17-24

Theoretical specific capacitance of Ni(OH)2 cannot be

International Conference on Current Advancements in Nano Sciences and Engineering

(ICANSE – 2016) achieved without using doping material like Cobalt,

Aluminum etc.

In this paper we synthesized nanosized Ni(OH)2 and

modified Ni(OH)2 by a simple chemical precipitation method.

The specific capacitance of Ni(OH)2 used as a single material

was very less which can be improved by using

ethylenediamine. Specific capacitance of modified Ni(OH)2 increased because of its porous nature and increase in specific

surface area.

II. EXPERIMENTAL

A. Materials and method

Synthesis of Ni(OH)2: Ni(OH)2 was synthesized by the

chemical precipitation method. In typical synthesis 2g Ni(NO3)2 . 6H2O (Merk) were dissolved in 100 ml of DI water

under magnetic stirring. After 15 minutes 1M NaOH solution

(14ml) was added drop-wise in the above solution to maintain

pH up to 10. Because of NaOH addition solution colour

changed greenish to faint greenish. Stirred this solution 2

hours and precipitate particles separated using a centrifuge.

These particles were washed three-four times with distilled

water and then kept in oven at 700 C for drying purposes for 8

hours. The dry powder thus obtained is used for making active

electrode.

Synthesis of modified Ni(OH)2: In the case of Ni(OH)2

synthesis 2 gm Ni(NO3)2. 6 H2O were dissolved in 100 ml of

DI water under continuous magnetic stirring about an 15

minute. Ethylenediamine is added in the above solution and

stirred about anhalf hour. Because of surfactant colour of

solution changed green to bluish. After that 1 M NaOH solution was added dropwise in to this solution and same time

maintained ph up to 10. Stirred this solution 2 hours. Washed

this particle three–four times with DI water and ethanol and

transferred to oven at 700C about a 8 hours. Finally faint green

coloured Ni(OH)2 formed in the form of power.

B. Characterization

The structure and lattice constant information of

prepared sample was obtained by using Powder X-Ray

Diffraction (PXRD) pattern using a Philips powder

diffractometer PW3050/60. The measurement was performed

by using 40 kV, 30 mA graphite filtared Cu-Ka radiation

(ʎ=1.54060 Ȧ). To examine topography of obtained materials,

SEM and AFM of samples were observed using 3400N SEM

and Asylum Research MPF3D .respectively. TG/DTA study

were carried out using SDT Q 600 V8.3 build 101 instrument.

Heating rate of 100C /min in air and 4.2 mg were used.

Surface area was analyzed using Xego nanotools (Acorn

Area). Before measuring surface area, stability of the particles

was found out in various solution like ethanol, water, ethyl

glycol. Aslo after obtaining good stability solution, different

concentration solvent (10mg, 15mg, 20mg, 30mg, 40mg,

50mg) was taken in same solvent and found out stability.

Stability of solution was also found out by adding carbon in

different weight percentage. And after that surface area was

measured in good stability solution. The electrochemical

experiments were carried out using an Eco-Chemie (The

Netherlands) make electrochemical system Autolab PGSTAT

100 running with GPES (General Purpose Electrochemical

System) version 4.9, software. Cyclic voltammetric and

impedance experiments were carried at room temperature (250

C) in a three-electrode cell set up. The working electrode was

carbon paste electrode with 2 mm diameter. Carbon paste

made from spectroscopic grade carbon powder and silicon oil

was mixed thoroughly using mortar and pestle with the

supercapacitor materials (oxides and hydroxides of cobalt and

nickel) material at 1:1 ratio forming homogeneous mixture

with carbon paste. Saturated calomel (SCE) was used as a

reference electrode and platinum wire was used as the counter

electrode. All general chemicals used in the present study are

of analytical-reagent grade. Nano pure water was used in all

the experiments and also for the washing of the

electrochemical cell set up.

III. RESULT AND DISCUSSION

Figure 1A shows the XRD patterns of the as-

synthesized Ni(OH)2 materials. The diffractions at the 2θ

values of 19.770, 33.36

0, 38.83

0, 52.59

0, and 62.97

0 in Fig. 1A

are typical for the hexagonal phase of Ni(OH)2 (JCPDS: 14-

0117) and indexed to the (001), (100), (101), (102), (110) and

(111) planes, respectively,4 confirming the formation of β-

Ni(OH)2. Ni(OH)2 consist of hexagonal planner aggrangement

and in case of β- Ni(OH)2 layer perfectly stacked with

interlayer distance about 0.46 nm. Ni(OH)2 grows along [110]

and [110] direction.21

Reflection peaks at the 2θ values 20.090,

33.330, 38.41

0, 59.36

0, and 62.58

0 shown in Figure 1B

corresponding to (001), (100), (101), (110) and (111) planes

are attributed to the hexagonal phase of Ni(OH)2 with

ethylenediamine. Broading of XRD peaks (011) may result

from small grain size or structural misdistortion in crystal.

10 20 30 40 50 60 70 80

2000

4000

6000

8000

10000

Inte

ns

ity

/ c

ps

Two Theta

a. Ni(OH)2

b. Modified Ni(OH)2

(001)

(100)

(101)

(102)

(110)

(111)

Figure 1. The XRD pattern of the as synthesized β-Ni(OH)2 and Modified

Ni(OH)2.

The low intensity and broad diffraction peaks

suggest material is nanocrystalline and which good for

supercapacitor application because proton can easily permeate

International Conference on Current Advancements in Nano Sciences and Engineering

(ICANSE – 2016) through the bulk of Ni(OH)2 material. For β-Ni(OH)2 lattice

parameter of the crystal is a= 3.12 Ȧ and c= 4.6 Ȧ. In case

modified Ni(OH)2, ethylenediamine act as a co-ordination

agent prevent local precipitation some amount. And also act as

a strong chelating ligand absorb some special crystal facets’.

Result of this was growth in thickness of nanoplatlets than

level dimensions.

Figure 2. The AFM image for a) β- Ni(OH)2 b) Modified β-Ni(OH)2 c) 3D

image of β- Ni(OH)2 d) 3D image of modified β-Ni(OH)2.

AFM characterization it is justified that morphology

and height measurement of the Ni(OH)2 material. As shown in

figure 2 (a) and (b) Minimum particle diameter obtained in

case of β-Ni(OH)2 is 7.5 nm while in case of modified

Ni(OH)2 is 3 nm. As discussed above ethylenediamine plays

an important role in decreasing size of the particle. Hence

surface area of modified Ni(OH)2 is increased significantly. Fig. 2(c) and 2(d) shows 3D view of the AFM image of

Ni(OH)2 and modified Ni(OH)2.

Figure 3. The FESEM image of a) β-Ni(OH)2 b) Modified β-Ni(OH)2.

Morphology and microstructure of samples was

observed using field emission scanning electron micrographs

(FESEM). FESEM at a high value magnification for

hexagonal and nanosheet Ni(OH)2 shown in Figure 3(a) and

(b). Particles formed is a hexagonal shape for β-Ni(OH)2 while

in case of modified Ni(OH)2 flower leaf like nanosheets

(Figure 3 (c) and (d)) are attached to each other forming

porous structure. FTIR (Fourier transform infrared

spectroscopy) results shows in figure 4(a) and (b) for β-

Ni(OH)2 and modified β-Ni(OH)2, peaks between 500 and

750 cm-1

confirms presence of metal hydroxide stretching.

Both case β-Ni(OH)2 and modified Ni(OH)2 the sharp peak at 3636 cm

-1 is assigned to the stretching vibration mode (γ-OH)

of non hydrogen bonded hydroxyl group in Ni(OH)2. The

symmetric and anti symmetric stretching of carbonate anions

present in the interlayer space of Ni(OH)2 is exhibited at 1630

and 1381 cm-1

respectively. M-O stretching peak shown at 627

cm-1

in case of modified Ni(OH)2, which is absent in β-

Ni(OH)2.

500 1000 1500 2000 2500 3000 3500 4000

0.3

0.6

0.9

1.2

1.5

1.8

2.1

Tra

ns

imit

an

ce

(%

)

Wavenumber cm-1

Ni(OH)2

Modified Ni(OH)2

45

4.7

519.319

96

.19

13

00

.47

1379.9

8 1490.2

28

49

.72

29

21

.59

3636.9

37

76

.31

38

19

.19

45

7.0

7

522.2 6

28

.67

83

8.7

90

7.3

8

14

79

.1

14

79

.1

16

29

.51

29

28

.63

36

38

.34

37

76

.65

Figure 4. FTIR curves for a) β-Ni(OH)2 b) Modified β-Ni(OH)2.

TG and DTA curve shown in Fig. 5 describe

properties of material as change with temperature. There are

two stages of mass loss for both samples. The first

thermogravimatric step represents the loss of adsorbed water

or intercalated water

0 200 400 600 800

70

75

80

85

90

95

100

105 Ni(OH)2

Modified Ni(OH)2

We

igh

t (%

)

Temperature (0

C)

Fig. 5 a. TG analysis of Ni(OH)2 and modified Ni(OH)2.

The mass loss at first stage is 18.33 and 19.86% for sample Ni(OH)2 and modified Ni(OH)2. Second stage

corresponding to the decomposition of Ni(OH)2 to NiO

a

b

c

d

a a

b b

0 200 400 600 800

0.0

0.2

0.4

0.6

De

riv

. W

eig

ht

(%0

C)

Temperature (0C)

Ni(OH)2

Modified Ni(OH)2

a.

International Conference on Current Advancements in Nano Sciences and Engineering

(ICANSE – 2016) emerged at 350

0C and 375

0C and mass loss is 4.128 % and

2.186%. From fig. 5.5 showed shifting of curve towards

higher temperature for modified Ni(OH)2. It can be seen that

there was more adsorbed water in modified Ni(OH)2. And

reason for that, modified Ni(OH)2 is more stable may be

stronger electrostatic action between laminar caused by

ethylenediamine leading to more excessive positive charge. DTA curve showed endothermic reaction at 285.5

0C and

296.280C giving energy 236.1 J and 51.21 J energy foe

Ni(OH)2 and modified Ni(OH)2.

0 200 400 600 800

5

10

15

20

25

30

He

at

Flo

w (

W/g

)

Temperature (0

C)

Ni(OH)2

Modified Ni(OH)2

b.

Fig. 5 DTA analysis of Ni(OH)2 and modified Ni(OH)2.

From this it is clear that β- Ni(OH)2 has less porous

nature and carbon did not goes to the this pores but after increasing carbon percentage, carbon goes to the pores and

hence T2 decreases after some time. But in case of modified

Ni(OH)2 because of its porous nature T2 relaxation time

continuously decreases and after some time it became

constant. From stability test we used ethyl glycol as a solvent

for surface area measurement. There are two methods are used

for measurement of surface area T1 and T2, here we used T2

method. And surface area calculated of modified Ni(OH)2 is

10 times larger than β- Ni(OH)2.

In electrochemical characterization figure 6 (a) and

(b) shows the CV curves of Ni(OH)2 and Ni(OH)2 with

ethylenediamine in 1M KOH solution at the scan rate 1, 5, 10,

50, 100, 200, 300, 400,500 mV/s. β-Ni(OH)2 and modified

Ni(OH)2 electrode exhibits increasing current as scan rate goes

in increasing. The specific capacitance calculated at scan rate

1 mV/s is 200 F/g and 222 F/g for β-Ni(OH)2 and modified

Ni(OH)2 respectively. Figure 7 shows cyclic stability study of Ni(OH)2 and modified Ni(OH)2.

-0.2 0.0 0.2 0.4

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

1 mV/s

5 mV/s

10 mV/s

50 mV/s

100 mV/s

200 mV/s

300 mV/s

400 mV/s

500 mV/s

Cu

rre

nt

/ A

g-1

E/ V vs SCE

Ni(OH)2a.

-100 0 100 200 300 400 500 600

-50

0

50

100

150

200

250

Sp

ec

ific

Ca

pa

cit

an

ce

/ F

g-1

Scan Rate /mV/s

Ni(OH)2b.

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5

-0.05

0.00

0.05

0.10

0.15

0.20

Sp

ec

ific

ca

pa

cit

an

ce

F/g

E/ V vs SCE

1 mV/s

5 mV/s

10 mV/s

50 mV/s

100 mV/s

200 mV/s

300 mV/s

400 mV/s

500 mV/s

Modified Ni(OH)2

c.

-100 0 100 200 300 400 500 600

-50

0

50

100

150

200

250

Sp

ec

ific

Ca

pa

cit

an

ce

Fg

-1

Sacn rate mV/s

Modified Ni(OH)2

d.

Figure 6. CV curves for a) β-Ni(OH)2 c) Modified β-Ni(OH)2 at scan

rate 1 5, 10, 50, 100, 200, 300, 400, 500 mV/s. b) and d) variation of

specific capacitance with respect to scan rate of β-Ni(OH)2 and

Modified β-Ni(OH)2 respectively.

Conclusion

Ni(OH)2 plays an important role in supercapacitor

application because of its theoretical high capacitance and

low cost. Also as the surface area increases specific

capacitance increases. Nanostructured ß- Ni(OH)2 synthesized

by a simple chemical precipitation method. XRD result and

FTIR (3636 cm-1

peak) confirm β- Ni(OH)2 and also change in

crystale shape in case of modified Ni(OH)2. SEM revels that

hexagonal shape of nanoparticals for β-Ni(OH)2 From AFM

results it is clear that adding ethylenediamine we can decrease

particle size up to 3 nm. From cyclic voltammetric result

specific capacitance of Ni(OH)2 with ethylenediamine gives a

better capacitive performance than simple Ni(OH)2. Specific

capacitance obtained from modified Ni(OH)2 and Ni(OH)2 is

222 F/g and 200 F/g respectively.

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