“Study of Graphene based coin cell-type

symmetric supercapacitor”BY

Mr. Girish Sambhaji GundM. Sc.

UNDER THE GUIDANCE OF

Prof. C. D. Lokhande

M. Sc., Ph. D.

THIN FILM PHYSICS LABORATORY,

DEPARTMENT OF PHYSICS, SHIVAJI UNIVERSITY,

KOLHAPUR - 416 004 (INDIA)

2013

Objectives

Introduction to supercapacitor

Why graphene?

Graphene thin films by screen printing

Characterization of graphene thin films

Device fabrication and performance evaluation of coin cell-type

symmetric device based on graphene thin films in non-aqueous

electrolyte

Demonstration

Conclusions

Plan of Presentation

Objectives

To develop efficient, small size and low cost energy storage

device in order to employ in portable electronics.

The use of carbon based electrode material in supercapacitor as its

abundant in nature with the intention to replace toxic and high cost

RuO2 and IrO2.

Supercapacitors

A Supercapacitor is an electrochemical capacitor that has an high

energy density and capacitance compare to ordinary capacitor.

APPLICATIONS

1. Power Electronics

2. Telecommunication

Devices

3. Satellites

4. Standby Power Systems

5. Electrical Hybrid Vehicles

ADVANTAGES OVER BATTERIES

1. Very high rates of charge and

discharge

2. Little degradation over hundreds of

thousands of cycles

3. Good reversibility

4. Low toxicity of materials used.

5. High cycle efficiency (95% or more)

Types of Supercapacitor

Electric Double layer capacitors (EDLCs): The storage

mechanism involves charge separation at electrode – electrolyte interface

(carbon based).

Pseudocapacitors: Pseudocapacitance arises from reversible Faradaic

reactions occurring at the electrode, and is denoted as ‘pseudo’-capacitance

in order to differentiate it from electrostatic capacitance.

Requirements for Supercapacitive electrode:

High conductivity

Large surface area

Good chemical stability

Good reversibility

Materials used for supercapacitors

Carbon

Transition Metal Oxides

Conducting Polymers (Polyaniline, Polypyrrole etc)

Why Graphene?

Among the all carbon allotropes, graphene has an attractive view because

of the,

High electrical conductivity

High specific surface area

High mechanical strength

High chemical stability

Reduction of graphite oxide to graphene:

Graphite Oxide was synthesized through Hummers method

Graphite oxide (1 mg ml-1) with water

Addition of 1ml of HH in 50 ml GO solution

Ultra-sonication for 30 minutes

Hydrothermal treatment at 180 C for 12 hr

Graphene precipitated

Filtered and washed

Dried at 70 C for 24 hr

Centrifuged at 16,000 rpm and solution is separated

Graphene thin film through Screen printing

method :

Paste = Graphene (90%) + Tr-X-100 (10%)

Squeegee blade

Graphene thin film

Screen

Structural and Morphological measurements:

BET Study:

Fabrication of coin cell-type symmetric supercapacitor

device:

Electrochemical measurements:

81 F g-1

S.E. = 24.5 Whkg-1

S.P. = 10 kWkg-1

ESR = 85.2 Ω cm-2

Rct = 121.3 Ω cm-2

36 F g-1

Conclusions

Successfully fabricated coin cell-type symmetric supercapacitor

based on graphene thin film with economical construction route.

Electrochemical measurements exhibits boost up performance of

graphene based coin cell-type symmetric supercapacitor device,

like specific capacitance of 81 Fg-1, specific energy of 24.5 Whkg-1

and specific power of 10 kWkg-1.

The obtained performance can be further enhanced through using

composite electrode material of graphene and metal oxides or

polymers or both.

Department of Physics, Shivaji University, Kolhapur.

DAE-BRNS, Mumbai.

Acknowledgement