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Two-Phase Colloid System


       Continuous phase        Dispersed phase        Descriptive names
       Gas             ...
Potential Determining Ion 1


                                                 1. Potential determining
                  ...
Potential Determining Ion in oxide




Advanced Electronic Ceramics I (2004)




                          Iso-electric po...
Electric Double Layer




Advanced Electronic Ceramics I (2004)




                                   Poisson equation


...
Debye-Hückel approximation




Advanced Electronic Ceramics I (2004)




                          Debye-Hückel approximat...
Example




Advanced Electronic Ceramics I (2004)




                                        Example




Advanced Electro...
The meaning of double layer thickness




Advanced Electronic Ceramics I (2004)




                      The meaning of d...
Ultracapacitor (Supercapacitor) for pulse power
                                                              Double-Layer...
Materials Issues in EDLC and Pseudocapacitor

                                               Charging



                 ...
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Aem Lect9

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Transcript of "Aem Lect9"

  1. 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. 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. 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. 4. Electric Double Layer Advanced Electronic Ceramics I (2004) Poisson equation Advanced Electronic Ceramics I (2004)
  5. 5. Debye-Hückel approximation Advanced Electronic Ceramics I (2004) Debye-Hückel approximation Advanced Electronic Ceramics I (2004)
  6. 6. Example Advanced Electronic Ceramics I (2004) Example Advanced Electronic Ceramics I (2004)
  7. 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. 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. 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)
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