THAI NGUYEN UNIVERSITY
UNIVERSITY OF AGRICULTURE AND FORESTRY
NGUYEN CHI CONG
FABRICATION OF SOLID STATE SUPERCAPACITORS
BY INKJET PRINTING
BACHELOR THESIS
Study mode: Full-time
Major:
Environmental Science and Management
Faculty:
Advanced Education Program Office
Batch:
2014-2018
Thai Nguyen, 25/09/2018
DOCUMENTATION PAGE WITH ABSTRACT
Thai Nguyen University of Agriculture and Forestry
Degree Program
Student name
Studen ID
Bachelor of Environmental Science and Management
Nguyen Chi Cong
DTN1454290005
FABRICATION OF SOLID STATE SUPERCAPACITORS
Thesis Title
BY INKJET PRINTING
Prof. Kuan-Jiuh Lin – National Chung Hsing University,
Taiwan.
Supervisor(s)
Dr. Nguyen Thanh Hai – Thai Nguyen University of
Agriculture and Foresttry, VietNam.
Abstract:
CNT ink and MnO2 ink were produced to fabricate solid state
supercapacitor electrodes through contactless deposition. We used inkjet
printing technology to deposit CNTs on photo paper to produce a conductive
film of 500 Ω/sq., followed by depositing manganese dioxide on the conductive
film to enhance its capacitive properties. The electrochemical properties of
CNT/MnO2 were significantly improved, and the most complete CNT/MnO2-20
capacitance value in the structure was 431.25 μF/cm2, which is nearly 3.5 times
as high as that of CNT with 125.52 μF/cm2. In addition, the capacitor system
adopts solid electrolyte. This type of electrolyte is free from danger of liquid
leakage, therefore the packaging cost will be reduced.
Key-words:
Ink jet printing; Solid state supercapacitor; CNT/MnO2
i
nanowire; Carbon nanotube; Contactless deposition.
Number of pages:
59
Date of submission:
25th September, 2018
Supervisor’s
signature
ii
ACKNOWLEAGEMENT
First of all, I would like to thank the coperation between Thai Nguyen
University of Agriculture and Forestry and National Chung Hsing University for
providing me an amazing opportunity to conduct my internship in Taiwan. It brings
me great pleasure to work and submit my thesis for graduation.
It is my pleasure to work with a profound supervisor - Professor Kuan-Jiuh
Lin whose guidance, encouragement, suggestion and very constructive criticism have
contributed immensely to the evolution of my idea during the project. Without his
guidance, I may not have this thesis.
I sincerely thank Dr. Nguyen Thanh Hai for his advices, assistance, sharing
experiences before and after I went to Taiwan, helping me to understand and
complete my proposal and thesis. He also helped me a lot by spending much time for
checking my thesis report.
I consider it is an honor to work with Mr. Wu, an exceptional master student,
who is particularly helpful in guiding me toward a qualitative methodology and
inspiring me in whole period of internship time. He is always helpful, friendly and
very kind with me. Without his guidance, I cannot accomplish this thesis.
Thank to Mr. Lai and all the member in KJ lab who hearty helped me a lot
when I worked in there. I am really fortunate to be a member of Professor KuanJiuh Lin’s Laboratory.
Finally, I would like to express my deeply gratitude to my family and friends for
providing me emotional, unceasing encouragement, physical and financial support. I
would like to thank all those other persons who helped me in completing this report.
iii
Because of my lack knowledge, the mistake is inevitable, I am very grateful if I
receive the comments and options from teachers and others to contribute my report.
Sincerely yours,
Nguyen Chi Cong
iv
TABLE OF CONTENTS
DOCUMENTATION PAGE WITH ABSTRACT ............................................... i
ACKNOWLEAGEMENT .................................................................................. iii
TABLE OF CONTENTS ..................................................................................... v
LIST OF FIGURES ............................................................................................ vii
LIST OF TABLES ............................................................................................... x
LIST OF ABBREVIATIONS ............................................................................. xi
PART 1. INTRODUCTION ............................................................................. 1
1.1. Research rationale .........................................................................................1
1.2. Research’s objectives ....................................................................................1
PART 2. LITERATURE REVIEW .................................................................. 3
2.1. Supercapacitors review .................................................................................3
2.1.1. Electric double-layer capacitors ................................................................. 4
2.1.2. Pseudo-capacitors ....................................................................................... 6
2.2. Carbon nanotube inkjet printing review........................................................9
2.2.1. Carbon Nanotube Dispersion ................................................................... 10
2.3. Manganese dioxide..................................................................................... 11
PART 3. METHODS AND MATERIALS .................................................... 15
3.1. Experimental Instruments .......................................................................... 15
3.2. Experimental materials............................................................................... 16
3.3. Experimental methodology ........................................................................ 16
3.4. Synthesis Methods................................................................................... 17
v
3.4.1. Preparation of CNT ink ............................................................................ 17
3.4.2. Synthesis of MnO2 nanowires .................................................................. 17
3.4.3. Preparation of MnO2 ink .......................................................................... 18
3.4.4. Single Electrode Production ..................................................................... 18
3.4.5. Solid Electrolyte Production .................................................................... 18
3.4.6. Preparation of solid state Supercapacitor Devices ................................... 18
3.5. Material Characteristics Analysis .............................................................. 19
3.6. Measurement of super capacitor electrode elements ................................. 20
PART 4. RESULTS AND DISCUSSION ...................................................... 22
4.1. Carbon Nanotube Synthesis and morphology identification ..................... 22
4.2. Synthesis of MnO2 nanowires .................................................................... 24
4.3. MnO2 NW printed on conductive substrate CNT ...................................... 27
4.4. Identification of CNT/MnO2NW morphology ........................................... 29
4.5. CNT/MnO2NW-5, 10, 20, 30 cyclic voltammetry ..................................... 32
4.6. CNT/MnO2NW-20 Constant Current Charge and Discharge Cycle Test .. 34
4.7. Series Capacitor Charge and Discharge Test ............................................. 40
4.8. Comparison of Literature ........................................................................... 41
4.9. Long-cycles stability .................................................................................. 42
PART 5. CONCLUSION ................................................................................. 43
REFERENCES ................................................................................................. 44
vi
LIST OF FIGURES
Figure 2.1.
Power density and energy distribution of conventional capacitors,
batteries, fuel cells, and supercapacitors (Source: Internet) .................. 3
Figure 2.2.
Relationship between interface distance and potential between two
conductors .............................................................................................. 5
Figure 2.3.
Electric double layer charge distribution model (a) Helmholtz
model, (b) Gouy-Chapman model and (c) Stern model ........................ 6
Figure 2.4.
Carbon tubes and overlapping carbon tubes form an electron
pathway................................................................................................ 10
Figure 2.5.
(a) α-Manganite; (b) β-Pyrolusite; (c) γ-Nsutite; (d) δ-Bismuthite;
(e) Crystal structure of λ-Spinel and (f) ε-Ramsdellite phase of
MnO2 ................................................................................................... 13
Figure 2.6.
CV curves for α, β, γ, δ, and λ-MnO2 in a 0.1 mol Na2SO4
electrolyte system ................................................................................ 13
Figure 2.7.
Electrochemical deposition MnO2 nanotubes (a) SEM Image and
(b) in 1 mol Na2SO4 in the electrolyte system, the current density
is 1 A/g , 2 A/g , 5 A/g , 10A/g charge and discharge curve ............... 14
Figure 2.8.
(a) TEM images of MnO2-MWCNTs composites and (b) Charge
and discharge curves at current densities of 0.2 A/g, 0.5 A/g, and
1 A/g, respectively, in a 0.5 mol Na2SO4 electrolyte system ............. 14
Figure 3.1.
Two electrode patterns and assembly .................................................. 19
Figure 3.2.
Bipolar device ...................................................................................... 19
Figure 3.3.
Supercapacitor test equipment configuration ...................................... 21
Figure 4.1.
Surface resistance and SDS/MWCNT ratio ....................................... 23
Figure 4.2.
(a) and (b) Low-magnification and high-magnification SEM
images of 0.2g CNT and 0.16g SDS on paper after being printed
20 time, (c) EDS spectrogram ............................................................. 23
Figure 4.3.
(a) and (b) SEM images of MnO2 nanowires at a holding
temperature of at 0.080M for 0.039M MnSO4 • H2O and 0.099M
KMnO4 precursor solutions, (c) EDS spectrogram ............................. 24
vii
Figure 4.4.
Growth of MnO2 Nanowires ............................................................... 25
Figure 4.5.
SEM images of MnO2 nanowires synthesized from 0.039M
MnSO4•H2O and 0.1M KMnO4 precursor solutions at 180°C for
1h (a), 4h (b) and 12h (c) .................................................................... 26
Figure 4.6.
XRD pattern of MnO2 nanostructures prepared by holding a
solution of 0.039M MnSO4 • H2O and 1M KMnO4 precursors at
180°C for 1 hour, 4 hours and 12 hours .............................................. 27
Figure 4.7.
CNT/MnO2 NW Cyclic Voltammogram at low scan rates ................. 29
Figure 4.8.
CNT/MnO2 NW Cyclic Voltammogram at high scan rates ................ 29
Figure 4.9.
SEM image of CNT/MnO2NW-5 ........................................................ 30
Figure 4.10.
SEM image of CNT/MnO2NW-10 ...................................................... 31
Figure 4.11.
SEM image of CNT/MnO2NW-20 ...................................................... 31
Figure 4.12.
SEM image of CNT/MnO2NW-30 ...................................................... 31
Figure 4.13.
Cyclic voltammograms of MnO2NW printed at different times in
1mV/s................................................................................................... 33
Figure 4.14.
Cyclic voltammograms of 20 cycles of MnO2NW printed at
different scan rates ............................................................................... 33
Figure 4.15.
Specific Capacitance Values of CNT/MnO2NW at different
Scanning Rates for different Print Times ............................................ 33
Figure 4.16.
Constant Current Charge and Discharge Graphic of Pure CNT ........ 37
Figure 4.17.
Constant current charge and discharge pattern of CNT/MNO2NW5 ........................................................................................................... 37
Figure 4.18.
Constant current charge and discharge pattern of CNT/MNO2NW10 ......................................................................................................... 37
Figure 4.19.
Constant
current
charge
and
discharge
pattern
of
CNT/MNO2NW-20 ............................................................................. 38
Figure 4.20.
Constant current charge and discharge pattern of CNT/MNO2NW30 ......................................................................................................... 38
Figure 4.21.
Constant current charge and discharge pattern at 0.25μA/cm2 ........... 38
viii
Figure 4.22.
Comparison of galvanostatic charge/discharge capacitance values
at different current densities ................................................................ 39
Figure 4.23.
Charge and discharge diagram of two series electrodes...................... 40
Figure 4.24.
Comparison with Single Electrode Charge and Discharge ................. 41
Figure 4.25.
Long-cycles stability ........................................................................... 42
ix
LIST OF TABLES
Table 2.1.
Channel Forms and Dimensions of MnO2 allotropes ......................... 13
Table 3.1.
List of experimental Instruments ......................................................... 15
Table 3.2.
List of experimental materials ............................................................. 16
Table 4.1.
Cyclic Voltammetry Capacitance Data for MnO2NW Modified
CNTs of Different Orders .................................................................... 34
Table 4.2.
MnO2 Modified CNT Constant Current Charge/Discharge
Capacitance and Coulomb Efficiency Data for Different Times ........ 39
Table 4.3.
Specific
capacitance
and
coulombic
efficiency
data
of
CNT/MnO2NW-20 at different current densities ............................... 39
Table 4.4.
Different Non-Contact Deposition Methods vs. Capacitor Data for
Solid state Superapacitors with Different Carbon Materials ............... 42
x
LIST OF ABBREVIATIONS
EDLC
Electric Double Layer Capacitor
IHP
Inner Helmholtz plane
DI
Deionized
PVA
Polyvilyl Alcohol
LiCl
Lithium Chloride
SDS
Sodium Dodecyl Sulfate
MWCNTs
TEM
FETEM
SEM
FESEM
Multi-walled Cacbon nanotubes
Transmission electron microscopy
Field-Emission Transmission Electron Microscope
Scanning Electron Microscope
Field-Emission Scanning Electron Microscope
XRD
X-ray diffraction
EDS
Energy-dispersive X-ray spectroscopy
CNTs
Cacbon nanotubes
NW
Nanowire
xi
PART 1. INTRODUCTION
1.1. Research rationale
Ink Jet Printing is used to fabricate conductive thin films for manufacturing
supercapacitors, which makes the appearance of the capacitors more diversified. It is
generally used in the manufacture of conductive pattern electronic devices. Nowadays,
photolithography is widely used. However, this technique requires many steps such as
etching, electroplating, and the like, which are time-consuming, complicated, and
expensive. Compared with lithography, ink jet printing is not only easy to obtain and
low cost, but also the use of non-contact deposition method to obtain conductive
patterns, allows us to easily control the pattern geometry, location, conductivity,
thickness and uniformity. In addition to conductive patterns, inkjet printing also has
many other applications, such as transistors, light emitting devices, solar cells,
memory and magnetic device applications, individual sensors and detectors. Ink’s
choices include Nanoparticle silver ink, Micron-size particle silver ink, Micron-size
particle carbon ink, Conductive polymer inks, Organic ink, etc. In addition, Ink Jet
Printing also has many limitations in terms of ink selection: The nozzle aperture is
small, so the ink there must be no problem with impurities and particles being too
large, and the viscosity may not be too large to make the printing process fail.
However, at present, few publications report on the production of energy storage
devices, so inkjet printing can solve the key application of this part.
1.2. Research’s objectives
Producing CNT ink, MnO2 ink, fabricating Solid Electrolyte, and synthesising
MnO2 nanowires through combination with a hydrothermal method.
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Basing on Ink Jet Printing technology to fabricate Single Electrode and Solid
State Supercapacitor.
Analyzing the morphology, crystal structure, elemental composition ratio and
distribution of the product.
2
PART 2. LITERATURE REVIEW
2.1. Supercapacitors review
Traditional capacitors, batteries, and fuel cells are common energy storage
sources. Supercapacitors are new types of energy storage devices. The power density
and energy distribution of conventional capacitors, batteries, fuel cells, and
supercapacitors are shown in Figure 2.1.
Figure 2.1. Power density and energy distribution of conventional capacitors,
batteries, fuel cells, and supercapacitors (Source: Internet)
From the figure above, it can be seen that the traditional capacitor has very high
power density, whereas the energy density is too low. In the other hand, the battery
and fuel cell have high energy density while the power density is low, and in the
vacant area is just filled up by the supercapacitor.
Supercapacitors, also known as electrochemical capacitors, are a new type of
electrochemical energy storage unit between a battery and a common physical
capacitor. They have high power density, long cycle life, and a simple working
principle. They are used in electric vehicles, communications, large industrial
equipment, aerospace, microelectronics equipment and other fields which have a wide
3
range of application prospects. The materials of supercapacitors are mainly classified
into carbon materials, metal oxides, and conductive polymers. The principle of power
storage of the super capacitor is divided into two types, one is an electric double-layer
capacitor (EDLC), with high specific surface area of carbon material as electrode
material; the other is a Faraday pseudo-capacitor. A continuous Faraday redox reaction
between the surface of the electrode and the electrolyte is used to store the electricity
using metallic materials as electrodes. Carbon materials can be divided into powdery
and fibrous forms. The preparation of active carbon into active carbon nanoparticles
can increase the surface area by 100 times compared with the original powder, and
increase the contact area, adsorption/desorption rate and adsorption capacity of
electrodes. With an increase in the adsorption capacity, a large amount of the
electrolyte solution is adsorbed, and an electric double layer is formed therein. Since
the contact area increases, the electrostatic capacity formed by the electric double layer
is 106 times compare with that of the ordinary capacitor. In transition metal oxides,
MnO2 has a high theoretical ratio of capacitor (1370 F/g) and a variety of allotrope that
have the highest specific capacitance in α-MnO2 (Chemical Engineering and
Processing 68 13-20, 2013).
2.1.1. Electric double-layer capacitors
The concept of electric double-layer was proposed by Von Helmholtz in the 19th
century. The main reason for its formation is that when two different kinds of
conductors come in contact with each other, there will be excessively charged ions or
electrons at the interface, causing a potential difference between the two conductors
(as shown in Figure 2.2). The further away from the interface, the less obvious is the
phenomenon of charge accumulation, and the lower the potential difference. In the
4
Helmholtz electric two-layer model (Figure 2.3(a)), the two different charges are
separated at the electrode/electrolyte interface with an atomic distance between them,
similar to a conventional dual parallel plate capacitor (Two-parallel plate conventional
capacitors) concept. Gouy and Chapman further modified the Helmholtz model to
consider that the positive and negative ions in the electrolyte exhibit a continuous
distribution due to the thermal motion, that is, the interaction of the opposite charges to
each other (Figure 2.3(b)), Unlike Helmholtz's model, only charges that are different
from the electrodes accumulate at the interface, and this continuously distributed area
is also called the diffuse layer. Stern will Helmholtz and Gouy-Chapman combines
two kinds of charge distribution models. It is believed that the electric double layer
should contain two layers of ion distribution, namely the inner compact layer or the
Stern layer and the outer layer (Figure 2.3(c)). In the Stern layer, ions are strongly
attracted by the electrodes and form an orderly arrangement. Among them, the
negative ions are adsorbed on the surface of the electrode by special adsorption of the
Hydration shell, forming the Inner Helmholtz plane (IHP); cations (usually in
solvation) (Chemical Engineering and Processing 68 13-20, 2013).
Figure 2.2. Relationship between interface distance and potential between two
conductors
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Figure 2.3. Electric double layer charge distribution model (a) Helmholtz model, (b)
Gouy-Chapman model and (c) Stern model
2.1.2. Pseudo-capacitors
The main difference between pseudo-capacitance and electric double-layer
capacitance is that the capacitive behavior of the pseudo-capacitance mainly depends
on the redox transition kinetics of the electrode material, in other words, the redoxreduction
ability between
the electrode surface and the electrolyte. Capacitance
behavior of the pseudo-capacitance will be determined. This Faradaic reaction usually
occurs on transition metal oxides with multiple Valence states. In addition, to be able
to generate rapid and reversible redox storage of electrical charges, pseudo-capacitives
also have the capacitance of an electrical double-layer capacitor, so the overall
capacitance presented
is higher than that of
electrical double-layer capacitors.
Compared to an electric double-layer capacitor (10-20 μF/cm2), the pseudocapacitance energy density (100 μF/cm2) is at least about 10 times higher. Common
transition metal oxides include RuO2, MnO2, NiO, etc (Chemical Engineering and
Processing 68 13-20, 2013).
6
2.1.3. Conductor ink
The most essential condition for various wearable electronic devices is electrical
conductivity because they must establish connections between different components.
Here a variety of conductive materials are introduced: metals, conductive polymers
and other conductive organic materials (carbon-based materials) have been used for
ink jet printed into a wearable electronic product (Measurement Science and
Technology 23 015601, 2012).
Metals are widely used as conductive electronic devices in printing because of
their advantages of high conductivity and stability. Metals can be ink printed by using
metal based particles or metal precursors. Among them, gold (Au) exhibits the most
excellent electrical conductivity, stability and inertness, and is a popular choice for
biocompatibility of printed wearable electronic products and can be used even in
contact with living tissues. Silver (Ag) is available as the wearable electronic device
utilizes the most commonly used metal in ink jet printing because it also has relatively
good performance and it still retains a relatively acceptable cost;... Because of their
low oxidation potential, they are easily oxidized in air, but they are also concerned
because of their price advantage. One of the solutions to the oxidation problem is to
cover the conductive ink material with a protective layer. Lee et al. synthesized a
stable copper nanoparticle in the air by coating a layer of a defective carbon shell film
to be formulated with a nano ink, and the conductive pattern can be completed.
Another method depends on the help of a reducing agent in the ink solvent by using
chemical sputtering or pulsed laser. Singler et al. manufactured a low-resistance fine
copper wire and obtained a low resistivity by a well-dispersed mussel-inspired
poly(dopamine) aqueous solution of ink. The electroless plating method was invented
7
by Grigoropoulos et al. to invent a high-resolution conductive pattern that can be
reduced and sintered by directly printing a nickel electrode and using a reducing agent,
toluene, to dissolve the solution. The reduction sintering procedure is achieved by
pulsed lasers (Measurement Science and Technology 23 015601, 2012).
Magdassi et al. invented the conductive nano ink without annealing step based on
the built-in sintering mechanism. By adding a destabilizing agent, NaCl, this will
separate the polymer protectant from the nanoparticles on the surface of the
nanoparticles. Therefore, the silver nanoparticles will self-sinter during the drying
stage, eliminating the need for Late sintering process. Chun et al. developed a new
low-temperature-processable Ag-salt conductive material ink, which eliminates the
need to cover it with a protective agent and can also increase the overall metal content.
Asawapirom et al. added tetramethylene sulfone (TMS) and dimethyl sulfoxide
(DMSO) to improve the conductivity of PEDOT:PSS, which can induce structural
changes and produce more linear intrachain structures and interchain interactions. Bao
et al. fabricated a highly conductive and transparent PEDOT:PSS film by
incorporating a fluorine-containing surfactant. Zboril et al. produced a well-dispersed
graphene hydrophilic functionalized multi-wall carbon nanotube (MWCNT) stabilizer.
Song et al. inkjet-printed highly conductive patterns using a mixture of metal and
graphene. The hybrid GO/Ag nanocomposite combines the high conductivity of Ag,
the performance and optical transparency of the GO backbone. In addition, selfassembled Ag nanosheets on GO can also be used as dispersants and stabilizers for
inks (Measurement Science and Technology 23 015601, 2012).
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