1. Two-Phase Colloid System
Continuous phase Dispersed phase Descriptive names
Gas Gas Impossible
Gas Liquid Fog, mist, aerosol
Gas Solid Smoke, aerosol, tear gas
Liquid Gas Foam
Liquid Liquid Emulsion
Liquid Solid Sol, colloidal solution,
gel, suspension
Solid Gas Solid foam
Solid Liquid Gel, solid emulsion
Solid Solid Alloy
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)

2. Potential Determining Ion 1
1. Potential determining
ions : [Ag+], [I-]
2. Indifferent Ions:
[NO3-], [K+]
Advanced Electronic Ceramics I (2004)
Potential Determining Ion 2
Advanced Electronic Ceramics I (2004)

3. Potential Determining Ion in oxide
Advanced Electronic Ceramics I (2004)
Iso-electric points in oxide
Materials Iso-electric point(pH)
SiO2 1-3
TiO2 6
Fe2O3 7-8
Al2O3 9
MgO 12.5
Ca5(PO4) 2(OH) [Hap] 9.5
For AgI, the point of zero charge should be given by
pAg = -log [Ag+] = -log (3 X 10-6) = 5.6
Advanced Electronic Ceramics I (2004)

4. Electric Double Layer
Advanced Electronic Ceramics I (2004)
Poisson equation
Advanced Electronic Ceramics I (2004)

5. Debye-Hückel approximation
Advanced Electronic Ceramics I (2004)
Debye-Hückel approximation
Advanced Electronic Ceramics I (2004)

6. Example
Advanced Electronic Ceramics I (2004)
Example
Advanced Electronic Ceramics I (2004)

7. The meaning of double layer thickness
Advanced Electronic Ceramics I (2004)
The meaning of double layer thickness
ϕ = 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)

8. Ultracapacitor (Supercapacitor) for pulse power
Double-Layer Capacitor (no redox)
Pseudo Capacitor (redox)
Advantages
- No limit in cyclic charging
- High Power density
Disadvantage
- Low energy density
- 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
http://www.ness.co.kr/
Advanced Electronic Ceramics I (2004)
Ultracapacitor & Batteries
http://www.chipcenter.com/eexpert/akruger/akruger008.html
Advanced Electronic Ceramics I (2004)

9. Materials Issues in EDLC and Pseudocapacitor
Charging
Discharging
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
Figures are from http://www.elna-america.com/PDF/DLC-chart(270,274).pdf
Advanced Electronic Ceramics I (2004)
Why EDLC?
http://www.ec-central.org/magazine/PDF/art_1_jul_aug_01.pdf
Advanced Electronic Ceramics I (2004)