Zeolite을 이용한 연료전지(Fuel Cell) 건국대학교 신소재공학 나노촉매소재 및 응용 연구실 김 화 중

What is Zeolite ? 3-D intracrystalline microporous alumino-silcate materials PBU(Primary Building Unit) SBU(Secondary Building Unit)

Framework Structure of Zeolite

Applications of Zeolite Catalyst and Catalyst Support Ion-Exchange Medium Separation Process Electrode and Electrolyte in Fuel Cell Others

Structures of Commercial Zeolites Zeolite A Zeolites X and Y

Structures of Commercial Zeolites ZSM-5

Structures of commercial Zeolites Mordenite ETS-10

VS 연료전지(Fuel cell) 왜 연료전지인가? 기존 화력발전 연료전지 연료 연료 열 에너지 기계적 에너지 전기 에너지 전기에너지 Nano-scale catalyst & application Lab. / Dep. of Materials Chemistry & Engineering

연료전지 응용 분야

2010년 연료전지 시장규모 예측

고분자전해질연료전지 PEMFC Nano-scale catalyst & application Lab. / Dep. of Materials Chemistry & Engineering

Basic Structure of Fuel Cell Basic Concept of Fuel Cell Electrochemical Reaction At Anode, 2H2 → 4H+ + 4e- At Cathode, O2 + 4e- + 4H+ → 2H2O Through Electrolyte, H+ passes

Different Types of Fuel Cell Type Mobile Ion Operating Applications Temperature(oC) Alkaline-AFC OH- 50 – 100 Used in space vehicle Proton-Ex H+ 50 – 100 Suitable for Vehicles and Membrane(PEM) Mobile but also for CHP Phophoric Acid H+ ∼ 220 200 kW CHP systems in use (PAFC) Molten carbonate CO32- ∼ 650 Suitable for medium to large (MCFC) scale CHP systems, up to MW capacity Solid Oxide(SOFC) O2- 500 – 1000 Suitable for CHP, 2 kW to MW

Proton Exchange Membrane Fuel Cell (PEMFC) First developed in the 1960’s (GM) During late 1980’s and early 1990’s, PEMFC, Renaissance of interest

Fuel Cell Be operated under hygroscopic condition Notwithstanding the good electrical conductivity of carbon, Carbon is relatively hydrophobic . High Electrical Contact Resistance . High Ohmic Power Loss

Polymer Electrolyte Polyethylene is modified by substituting fluorine for the hydrogen (Per-fluorination) Poly-fluoroethylene or PTFE (Teflon) . Resistant to chemical attack and durable . Highly hydrophobic : Expel water molecules out of the electrode

Nafion Type Membrane Structure Hydrophilic site

Electrodes Comprises a catalyst to facilitate the reaction ● Catalyst : Platinum - Dispersed and supported on a high surface area support material ● Support Material : exclusively Carbon material - Good electrical conductivity : Facilitate the passage of the protons through membrane formed on catalyst while facilitates the flow of electrons to the external circuit from the electrode

Electrodes and Its Structure Carbon supported Pt Catalyst Pt Particle Carbon Support

Zeolite-Carbon hybrid type electrode (ETS-10, ZSM-5…) Carbon black Catalyst particle ELECTROLYTE = Polymer + Zeolite

Characteristics of Zeolite in Fuel Cell Excellent water retention ability (Hydrophilic) Excellent proton ponductivity High Surface area High Pt dispersion

Fuel Cell Electrode with Conductive Zeolite Support Material Conventional PEMFC(Polymer-Electrolyte Membrane Fuel Cell) ● Structure of Fuel Cell - Exclusively Carbon particles as a support material Membrane Anode (Pt over carbon) e- Cathode (Pt over carbon)

Zeolite-Carbon Hybrid type MEA(Membrane-Electrode Assembly) Pt-Zeolite Layer GDL Membrane Pt/C Layer H+ Nafion 115 Carbon particle Pt/Carbon particle MEA assembled with Alternative electrode(GCZ) H2 Pt particles in pore and outer surface of ZSM-5 e- Composite Layer MEA assembled with composite electrode

Pt-ZSM-5 Pt(111) Pt(200) Pt(220) Pt(311) XRD results

Pt-ZSM-5 TEM images 2~5nm Pt Particle size

Fabrication of MEA(Membrane Electrode Assembly)

Electrode Mapping results Case Ⅰ Case Ⅱ Commercial ■: Nafion, ■: Zeolite or Carbon(Commercial), ■: Pt

CV results

Cell performance

Potential Application of Zeolite to Fuel Cell Advantages over Carbon Materials ● Provides Electrodes with lower electrical resistance and lower Ohmic power loss Because of its High Surface Area and Channel structure - Reduces the Cost of Catalyst - Creates the Higher Dispersion - Prevents the catalyst Particles from agglomeration - More hydrophilic than carbon - Relatively higher gas permeability

Synthesis of Nano-Pt particles using zeolite templating method Ion exchange of Pt(NH3)4Cl2 with zeolite Y Pt(NH3)4 - Y Furfuryl alcohol Polymerization Pyrolysis at 800oC Reduction under H2 Pt Nano Particles Advantages of Zeolite Templating method Steric effect prevent Pt cluster from the growth

c a b Transmission Electron Micrograph (TEM) of Pt nano particles formed within Zeolite Y pore channels

a b c Transmission Electron Micrograph (TEM) of Pt nano particles after removing Zeolite Y: a) 0.1oC, (b) 0.2oC and (c) 2.0oC of heating rate for the decomposition of Pt(NH3)42+

Zeolite-Polymer Composite Electrolyte Problems of Conventional Nafion Electrolyte in DMFC (Direct Methanol Fuel Cell) High Methanol Cross-Over Low Proton Conductivity

Zeolites Nafion® Study Concepts 2. 연구내용 및 결과 Pore Size : 5.6 ⅹ5.3 Å ZSM-5 Pore Size : 7.0ⅹ6.5 Å Mordenite MCM-41 20-100 Å Microporous crystalline aluminosilicates Regular pore size - Shape selectivity Selective sorption, Ion exchange, Catalytic activity High thermal stability High surface area High Chemical stability Water retention at high temperature -> Poor conductivity Methanol crossover High material cost

Organic Functionalize 2. 연구내용 및 결과 H+ MeOH Zeolite Polymer matrix Study Concepts Ion Exchange Organic Functionalize Sulfonation (PETMS)

MTI DMFC Samsung Note PC DMFC Toshiba DMFC(1W) Fujitsu note PC Smart Fuel Cell

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