NANOMATERIALS FOR SUPERCAPACITORS

PRESENTED BY: AFFAN SAFEER

REG # 223-FBASE/BSPHY/S12

OUTLINE

CAPACITOR

SUPERCAPACITOR

BASIC CONSTRUCTION OF SUPERCAPCITOR

WORKING OF SUPERCAPACITOR

CHARACTERISTICS OF ELECTRODES

MATERIALS USED FOR ELECTRODE IN SC

CHARGING OF SUPERCAPACITORS

CAPACITORS

Capacitor is an electronics component which is used to store charge in the form of electric potential

Capacitor is consists of two parallel plate which is separated by a small distance in few millimeters

Amount of Charge store in the capacitor is known as capacitance of capacitors and it’s depend upon dimensions of the capacitors

The capacitance increase or decrease changing dimensions of the capacitor and material used in it

SUPERCAPACITORS

Supercapacitors (SC) are specially designed capacitor which has huge capacitance value and energy density

Supercapacitors are belongs to family electrochemical capacitor and it’s worked on electric double layer (EDL) mechanism

Supercapacitors can be defined as energy storage device that stores energy electrostatically by polarizing the electrolytic solution.

BASIC CONSTRUCTION OF SUPERCAPACITORS

A Supercapacitor consist of two porous electrodes

A membrane, which separates positive and negative plated is calledseparator

Electrodes are electrically connected with ionic liquid called electrolyte

WORKING OF SUPERCAPACITORS

When the voltage is applied to positive electrode it attracts negative ionsfrom electrolyte.

When the voltage is applied to negative electrode, it attracts positive ionsfrom electrolyte

These ions are stored near the surface of electrode and this ions decrease distance the between the electrodes

Due to decrease of distance electrodes, the capacitance become very huge.

𝐶 𝛼𝐴

𝑑

CHARACTERISTICS OF ELECTRODES

Electrodes used in SC have good conductivity, high temperature stability, high resistance and high surface areas per unit volume or mass.

These electrodes made up of pores carbon

Sizes of pores is in range micropores (less than 2 nm) to mesopores (2-50 nm)

Generally the smaller the electrode pores, increases the capacitance and energy density but decrease the power density

MATERIALS USED FOR ELECTRODE IN SC

The most commonly used material for electrode in supercapacitors is Carbon in various forms such as

• Activated carbon

• Carbon aerogel

• Graphite (graphene)

• Carbon nanotubes (CNTs), etc.

MATERIALS USED FOR ELECTRODE IN SC

Activated carbon (AC):

Activated carbon is a form of carbon processed to have low-volume density and small pores that increase the surface area available for adsorption.

AC is extremely porous with high electrical conductivity and high surface area

Solid AC is most used electrode materials for SC.

AC electrode with surface density about1000 m2/g results in a typical double-layer capacitance of about 10 μF/cm𝟐 anda specific capacitance of 100 F/g.

MATERIALS USED FOR ELECTRODE IN SC

Carbon aerogel:

Carbon aerogel is a highly porous, synthetic, ultralight material derived froman organic gel in which the liquid component of the gel has been replaced witha gas.

Carbon aerogel electrode are more conductive than activated carbon.

Carbon aerogel electrode with surface density of about 400-1200 m2/g givesspecific capacitance of 104 F/cm3, energy density of 325 J/g and power densityof 20 W/g

MATERIALS USED FOR ELECTRODE IN SC

Graphene:

Graphene is pure carbon in the form of a very thin sheet with atoms arranged in a regular hexagonal pattern, also called "nanocompositepaper”.

Graphene electrode with surface density of 2630 m2/g gives specific capacitance of 550 Faraday per gram

MATERIALS USED FOR ELECTRODE IN SCCaron Nanotubes (CNTs):

CNTs have high surface area and electrical conductivity

CNTs electrodes improve capacitor performance, due to the surface area and high conductivity.

CNTs based SC store about the same charge as activated carbon based SC per unit surface area but CNTs surface is arranged in a regular pattern, providing greater wettability.

MATERIALS USED FOR ELECTRODE IN SC

CNTs have higher capacitance than activated carbon electrodes, e.g. 102 F/g for Multi well nanotubes and 180 F/g for Single

well nanotubes .

CHARGING OF SUPERCAPACICTORS

Negative electrode (red), Positive electrode (blue)Positive charge (green), Negative charge (purple)