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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)