Post on 02-Jun-2015
Advanced Electronic Ceramics I (2004)
Two-Phase Colloid System
Continuous phaseGasGasGasLiquidLiquidLiquid
SolidSolidSolid
Dispersed phaseGasLiquidSolidGasLiquidSolid
GasLiquidSolid
Descriptive namesImpossibleFog, mist, aerosolSmoke, aerosol, tear gasFoamEmulsionSol, colloidal solution, gel, suspension
Solid foamGel, solid emulsionAlloy
Paul C. Hiemenz, “Principles of colloid and surface,”
Advanced Electronic Ceramics I (2004)
Electrostatic interaction between particles
Www.zeta-meter.com
Advanced Electronic Ceramics I (2004)
Potential Determining Ion 1
1. Potential determiningions : [Ag+], [I-]
2. Indifferent Ions:[NO3-], [K+]
Advanced Electronic Ceramics I (2004)
Potential Determining Ion 2
Advanced Electronic Ceramics I (2004)
Potential Determining Ion in oxide
Advanced Electronic Ceramics I (2004)
Iso-electric points in oxide
Materials
SiO2
TiO2
Fe2O3
Al2O3
MgOCa5(PO4) 2(OH) [Hap]
Iso-electric point(pH)
1-367-8912.59.5
For AgI, the point of zero charge should be given bypAg = -log [Ag+] = -log (3 X 10-6) = 5.6
Advanced Electronic Ceramics I (2004)
Electric Double Layer
Advanced Electronic Ceramics I (2004)
Poisson equation
Advanced Electronic Ceramics I (2004)
Debye-Hückel approximation
Advanced Electronic Ceramics I (2004)
Debye-Hückel approximation
Advanced Electronic Ceramics I (2004)
Example
Advanced Electronic Ceramics I (2004)
Example
Advanced Electronic Ceramics I (2004)
The meaning of double layer thickness
Advanced Electronic Ceramics I (2004)
The meaning of double layer thicknessϕ = ϕ0 exp (-κx)at x= 1/κ (double layer thickness)ϕ = ϕ0/e
the double layer thickness: the distance over which significant potential exist
as double layer thickness ↓→ repulsive force ↓→ coagulation ↑
Advanced Electronic Ceramics I (2004)http://www.ness.co.kr/
Ultracapacitor (Supercapacitor) for pulse power
- All-weather quick start applications- Load-leveling and Uninterruptible Power Systems (UPS)- No Maintenance applications - Peak pulse power applications - Quick charge applications - Memory back-up applications - Automotive applications and Electric Vehicles
Double-Layer Capacitor (no redox)Pseudo Capacitor (redox)
Advantages- No limit in cyclic charging - High Power densityDisadvantage- Low energy density
Advanced Electronic Ceramics I (2004)http://www.chipcenter.com/eexpert/akruger/akruger008.html
Ultracapacitor & Batteries
Advanced Electronic Ceramics I (2004)Figures are from http://www.elna-america.com/PDF/DLC-chart(270,274).pdf
Materials Issues in EDLC and Pseudocapacitor
EDLC- The sophisticated design of the activated carbon• Too small pore : slow energy input and output• Too large pore and particle sizes : low capacitance- well-designed nano carbon (particle or tube containing nano-sized pore)
Pseudocapacitor- Preparation of nano-sized RuO2- High cost due to RuO2
Charging
Discharging
Advanced Electronic Ceramics I (2004)http://www.ec-central.org/magazine/PDF/art_1_jul_aug_01.pdf
Why EDLC?