FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
"Chemical synthesis of polythiophene thin film for supercapacitor application"
2. APPLICANT(S)
a) NAME: 1) Prof. Chandrakant Dnyandev Lokhande, 2) Miss. Bebi Hambirrao
Patil and 3) Dr. Vinayak Shivajirao Jamadade
b) NATIONALITY: All are Indians
c) ADDRESS: Thin Film Physics Laboratory,
Department of Physics, Shivaji University, Kolhapur-416 004(M.S.), India,
3. PREAMBLE TO THE DESCRIPTION
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it is to be performed

The following specification particularly describes and ascertains the nature of the present invention and the manner in which it is to be performed. Papers Related to Polythiophene Thin Films as Supercapacitor
1. B. Senthilkumar, P. Thenamirtham, R. Kalai Selvan, "Structural and
electrochemical properties of polythiophene", Applied Surface Science 257 (2011)
9063.
2. F. AM, M. K. Ram, P. Basnayaka, E. Stefanakos,. Y. Goswami, A. M. Hoff, and A.
Kumar, "Electrochemical Supercapacitors Based on Graphene-Conducting Polythiophenes Nanocomposite" ECS Transactions, 35 (2011) 167.
3. Li Liua, F. Tiana, Xi. Wanga, Zh.Yanga, M. Zhoua, Xi. Wang "Porous polythiophene as a cathode material for lithium batteries with high capacity and good cycling stability", Reactive & Functional Polymers 72 (2012) 45.
4. Graeme A. Snooka, Pon Kao, Adam S. Best, "Conducting-polymer-based supercapacitor devices and electrodes", Journal of Power Sources, 196 (2011) 1.
5. Qing Lu, Yikai Zhou, "Synthesis of mesoporous polythiophene/Mn02 nanocomposite and its enhanced pseudocapacitive properties", Journal of Power Sources, 196(2011)4088.
6. S. V. Kamat, S. H. Tamboli, V. Puri, R. K. Puri, J. B. Yadav, Oh Shorn Joo, "Post deposition heating effects on the properties of polythiophene thin films" Archives of Physics Research, 1 (2010) 119/
7. R. C. Liu, Z. P. Liu, "Polythiophene: Synthesis in aqueous medium and controllable morphology", Chinese Sci Bull., 54 (2009) 2028.
8. Marco F. Suarez Herrera, and Juan M. Feliu "Electrochemical Properties of thin Films of Polythiophene Polymerized on. Basal Plane Platinum Electrodes in Nonaqueous Media", J. Phys. Chem. B 113 (2009) 1899.
9. S. Richard Prabhu Gnanakan, M. Rajasekhar and A. Subramania "Synthesis of Polythiophene Nanoparticles by Surfactant - Assisted Dilute Polymerization Method for High Performance Redox Supercapacitors", Int. J. Electrochem. Sci., 4 (2009)1289.
10. D. Reyman, E. Guereca, P. Herrasti, "Electrodeposition of polythiophene assisted by sonochemistry and incorporation of fluorophores in the polymeric matrix",

Ultrasonics Sonochemistry, 14 (2007) 653.
11. C. Y. Wang, A. M. Ballantyne, S. B. Hall, C. O. Too, D. L. Officer ,G. G. Wallace, "Functionalized polythiophene-coated textile: A new anode material for a flexible battery" , Journal of Power Sources, 156 (2006) 610.
12. B. Ballarin, M. Facchini, L. Dal Pozzo, C. Martini, "Comparison of different porous sol-gel matrices: template synthesis of polythiophene", Electrochemistry Communications, 5 (2003) 625.
13. Marina Mastragostino, Catia Arbizzani, Francesca Soavi, "Conducting polymers as electrode materials in supercapacitors", Solid State Ionics, 148 (2002) 493.
14. Alexis Laforgue, Patrice Simon, Christian Sarrazin, Jean Franc, Ois Fauvarque, "Polythiophene-based supercapacitors", Journal of Power Sources, 80 (1999)142.
USA Patents

No. Patent No. Month and Year Inventors Classification
1. 20110168946 July 2011 Loevenich et al 252/301.35
2. 7341.801 November 2008 Reuter et al 429/128
3. 6522522 February 2003 Yu et al 361/502
4. 5300575 April 1994 . Jonas et al 528/379
5. 5035926 July 1991 Jonas et al 427/393.1
The present investigation deals with synthesis of polythiophene thin films by simple and cost effective successive ionic layer adsorption and reaction method (SILAR) at room temperature. The polythiophene films were deposited under optimized parameters such as concentration of monomer and oxidant solution, deposition time and pH of solution and number of cycles.
In the present work, we have deposited good quality, uniform, well adherent polythiophene films onto low cost stainless steel substrate by inexpensive successive ionic layer adsorption and reaction method (SILAR) and to get large specific capacitance value with high stability.
Chemical methods such as chemical deposition method (CDM), successive ionic layer adsorption and reaction method (SILAR), electrodeposition (ED) methods etc. are

simple, economic and convenient for the deposition of large area thin films. These are low temperature methods.
Among all these chemical methods, successive ionic layer adsorption and reaction method (SILAR) is an attractive method due to its some special following advantages,
1) The starting chemicals are easily available and cheap materials.
2) As relatively it is inexpensive, simple and convenient method for large area deposition. Variety of substrates such as semiconductor, insulator or metals can be
used.
3) It does not require sophisticated instrumentation like vacuum system and other expensive equipment.
4) It is low temperature process which avoids oxidation/corrosion of metallic substrates.
5) Unlike in electrodeposition, electrical conductivity of substrate is not a necessary requirement in chemical deposition method.
6) The preparative parameters are easily controllable to obtain good quality, well adherent and uniform films.
Among the conducting polymers, polythiophene is an intrinsically conducting polymer most studied because of its high conductivity, high storage ability, good thermal and environmental stability, high redox and capacitive current and biocompatibility.
Since 1980, polythiophene has been widely used in environmentally and thermally stable conjugated polymer materials. Thiophene belongs to the well-known aromatic heterocyclic ring monomers. In case of polythiophene electrons are delocalized along the
conjugated backbones of conducting polymers, usually through overlap of TT-orbitals,
resulting in an extended TT-system with a filled valence band. By removing electrons from
the TT-system ("p-doping"), or adding electrons into the TT-system ("n-doping"), a charged unit called a bipolaron is formed as shown in fig.l


Figure 1. Removal of two electrons (p-doping) from a PT chain produces a bipolaron.
Electrochemical supefcapacitor is a charge storage device that can withstand conventional or electrolytic capacitor. Recently, electrochemical capacitors have attracted considerable attention for use in high successive ionic layer adsorption and reaction method (SILAR) power energy storage devices, portable electronic devices, hybrid cars, buses and trucks. Generally electrochemical capacitors or supercapacitors based on the mechanisms of charge storage/delivery and can be divided into the electric double-layer capacitors and redox pseudocapacitors. In these electrochemical capacitors, the energy stored is either capacitive or pseudocapacitive in nature. The capacitive or non-faradaic process is based on charge separation at the electrode/solution interface. On the other hand, the pseudocapacitive process consists of faradaic redox reactions that occur within the active electrode materials. Carbon, conducting polymers and transition metal oxides are the most widely used active electrode materials. The conducting polymers have received increasing interest as an alternative to carbons and metal oxide semiconductors for supercapacitor application. Among the conducting polymers, polythiophene is the major attractive candidate as a supercapacitive material, due to their chemical stability in various redox states and excellent electronic and charge transport properties. Energy storage levels of 250 F. g"1 were obtained with UCIO4.
Essential features from commercial point of view demands small electrode area deposited supercapacitors with higher capacitance value and also preparation of supercapacitive material electrode and electrolyte used should be cost effective. The high specific capacitance and wide operating voltage window lead to superior energy density for


capacitors made with polythiophene. The energy, Es stored by electrochemical capacitors
can be described by the following formula:
Where, C is storage capacitance and V is cell voltage. It is therefore possible to increase the energy stored in the electrochemical capacitor by increasing the cell voltage (V), the storage capacitance (C), or both.
The present invention is better understood when read in conjunction with the following drawings, in which:
Fig. 1 is X-ray diffraction pattern of polythiophene thin film on stainless steel substrate.
Fig. 2 is scanning electron micrograph of polythiophene thin film.
Fig.3 is a cyclic voltammograms (CV) recorded for polythiophene thin film electrode in 0.1M LiC104 electrolyte at 5 mVs"1 scan rate after 1,000 cycles.
This invention provides a supercapacitor incorporating the electrode material of this invention. The supercapacitor includes: (1) a cathode (a negative electrode) comprising thin film of polythiophene on stainless steel substrate, (2) UCIO4 electrolyte and (3) a anode (a positive electrode) comprising platinum sheet electrode.
Another objective of this invention is to provide successive ionic layer adsorption and reaction method (SILAR) for preparation of polythiophene thin film on stainless steel substrates with good adherence. The polythiophene thin film electrodes according to the preferred embodiment of the present invention are prepared by the same method. Before the deposition, stainless steel substrates were mirror polished, then ultrasonically treated and well cleaned with double distilled water. Two beakers SILAR system is used for deposition of polythiophene thin film on stainless steel substrates. First beaker, contains thiophene solution prepared in acetonitrile serves as cationic source at room temperature. . The efficient polymerization of thiophene is took place only in an acidic environment. Second beaker contains solution of FeCb in double distilled water at room temperature acts as an oxidizing agent. First, the stainless steel substrates dipped in cationic precursor, i.e. acidic thiophene solution for few seconds in which thiophene monomers get adsorbed onto substrate surface. After immersion of the substrate into the FeCl3 solution at room

. temperature for few seconds, the polymerization occurred at substrate surface to form brownish polythiophene polymer. Thus one SlLAR cycle for deposition of polythiophene is completed. This cycle repetition is carried out several times to increase the thickness of polythiophene thin film.
Prepared polythiophene thin films were characterized by following techniques. The X-ray diffraction (XRD) patterns were obtained by X-ray diffraction analysis, with Philips (PW 3710) diffractometer using CrKa radiation (X.= 2.2897 A). Surface morphology was studied with the help of scanning electron microscope (JEOL, analytical scanning electron microscopy model JSM-6360A). The electrochemical analysis of the films deposited on stainless steel substrate was studied by cyclic voltammetry (CV) using the potentiostat (263A EG&G, Princeton Applied Research Potentiostat). The electrochemical cell comprises platinum as a counter, saturated calomel electrode (SCE) as a reference and polythiophene as a working electrode in 0.5 M LiC104 in propylene carbonate as electrolyte.
The following examples, according to preferred embodiments of the invention, demonstrate the features thereof. However, it is understood that such examples are not to be interpreted as limiting the scope of the invention as defined in the claims.
Example: 1
The polythiophene thin film is deposited onto stainless steel substrates using simple and inexpensive successive ionic layer adsorption and reaction method at room temperature in acidic media. The films of polythiophene brownish in colored and adhered well to the stainless steel substrate. From X-ray diffraction studies, amorphous nature of polythiophene thin film is confirmed. The SEM images confirmed the well-covered growth of polythiophene thin films on to stainless steel substrate. The deposition conditions are summarized as

1st monomer solution 0.5.M thiophene in acetonitrile solution.
2 nd oxidant solution 0.1 M FeCb in double distilled water.
Adsorption time in monomer solution 20 s.
Adsorption time in oxidant solution 10 s.
Deposition cycles 100

Deposition time
300 sec.
Substrate stainless steel
Temperature of bath 300 K
Structure and morphology Amorphous and compact morphology
Example: 2
The polythiophene film is deposited onto stainless steel substrate using simple and inexpensive successive ionic layer adsorption and reaction method at room temperature.XRD pattern reveals the amorphous nature of polythiophene film. The SEM micrograph shows the formation of compact growth of polythiophene on the stainless steel substrate. The different parameters of polythiophene film formation are as described in following table.

1st monomer solution 0.1M thiophene in acetonitrile solution.
2 nd oxidant solution 0.05M FeCl3 in double distilled water.
Adsorption time in monomer solution 20 s.
Adsorption time in oxidant solution 10 s.
Deposition cycles 100
Thickness of the film 0.72 mg/cm2
Substrate stainless steel
Temperature of bath 300 K
Structure and morphology Amorphous and compact morphology
Example: 3
The electrochemical study of polythiophene film electrode was carried out using a conventional three-electrode system using platinum as a counter electrode and saturated calomel electrode (SCE) as a reference electrode. The cyclic voltammograms (CV) were achieved in the 0.1 M LiC104 in propylene carbonate solution using scanning potentiostat for 5 mVs-1 scan rate. Number of cycles scanned for polythiophene thin film electrode was varied from 1-1,000 cycles with scan rate 5 mVs-1. A polythiophene thin film electrode showed stable supercapacitive characteristics up to 1,000 cycles. This is very important

aspect as concerned in electrochemical supercapacitor. The specific capacitance was calculated at different potential sweep rates, using following relation,

Where, I is average current in ampere, dV/dt is scanning rate in mVs-1. The specific capacitance of the electrode was achieved dividing capacitance by the weight dipped in the electrolyte, which was measured by weight difference method.
The maximum value of specific capacitance of 250 Fg"1 is achieved in 0.1 M L1CIO4 in propylene carbonate electrolyte with 85% stability. The supercapacitors made of the electrode according to this invention are especially suited for commercial applications, which require energy sources with high power, low voltage and high cycle life. These applications include: 1) Bridge power applications such as actuation systems and smart devices which require high power in duration few second or less, 2) Digital communication, 3) Hybrid electrical vehicles, 4) Load leveling applications etc.
We claim:
1 An electrochemical capacitor, said supercapacitor comprising, cathode comprising a film of polythiophene, an electrolyte and anode comprising a platinum sheet.
2 The electrochemical capacitor of claim 1, wherein, polythiophene is prepared by simple and inexpensive successive ionic layer adsorption and reaction method (SILAR) on stainless steel substrate.
3 The deposition of claim 2, wherein, deposition of polythiophene film is carried out by two beakers system, first beaker contains thiophene solution and second beaker contains FeCl3 solution act as oxidizing agent, at room temperature.
4 The method of claim 2, wherein, the concentration of thiophene solution precursor is in between 1-0.5M and the concentration of FeCl3solution is in between 0.05-0.1 M.
5 The method of claim 2, wherein, the thickness of polythiophene film is in the range of 0.48 to 0.72 mg/cm2by changing adsorption cycles in the range 60 to 100.

6 The method of claim 2, wherein, polythiophene film is amorphous and compact.
7 The supercapacitor of claim 1, wherein, the maximum value of specific capacitance 250 Fg-1, was achieved in 0.1 M L1CIO4 electrolyte with a stability of 1000 cycles was obtained in 0.1 M LiClO4 electrolyte with stability 85 %.
8 The supercapacitor of claim 1, 85 % stability of polythiophene thin film electrode is retained after 1,000 cycles in 0.1 M LiClO4 in propylene carbonate electrolyte at 5 mVs"1 scan rate.
9 A supercapacitor, as in claim 1, comprising; an cathode comprising polythiophene thin film onto stainless steel substrate, an electrolyte consisting of 0.1 M UCIO4 in propylene carbonate and a anode comprising a platinum sheet, substantially as herein described, with reference to the. examples.