Fuel Cell

Question 1

Full name of AFC, PEMFC, DMFC , PAFC, MCFC, SOFC

Answer 1

AFC: Alkaline FC
PEMFC: Proton Exchange Membrane FC
DMFC: Direct Methanol FC
PAFC: Phosphoric Acid FC
MCFC: Molten Carbonate FC
SOFC: Solid Oxide FC

Question 2

List Lower Temperature FC systems

Answer 2

AFC (50-200C)
PEMFC (30-100)
DMFC (20-90)
PAFC (~220)

Question 3

List Higher Temperature FC systems

Answer 3

MCFC (~650)
SOFC (500-1000)

Question 4

List FC with H+ as mobile ion

Answer 4

PEMFC
DMFC
PAFC

Question 5

Advantages of FCs

Answer 5

1. Almost zero emission of CO2
2. More efficient than combustion engines with a high efficiency (50-60%)
   3.High energy density than batteries
   4.Silent in use, attractive for combined heat and power (CHP system)

Question 6

Disadvantages of FCs

Answer 6

1.Expensive
2.Poor Durability in Cold Weather
3.No well-established H2 distribution network

Question 7

Applications of FC

Answer 7

1. Portable electronics applications(1-100W, DMFC,PEMFC)
2. Cars, boats and domestic CHP (1k-10kW, AFC/SOFC/PEMFC)
   3.Distributed power generation CHP, also buses (100k-10MW, MCFC/SOFC/PAFC)

Question 8

Exchange Formula of Alkaline Fuel Cells

Answer 8

Cathode:
O2+4e-+2H2O -> 4OH-
Anode:
2H2 + 4OH- -> 4H2O + 4e-

Question 9

Electrolytes of AFC

Answer 9

30-35% KOH

Question 10

Electrodes of AFC

Answer 10

Carbon-support catalysts, mixed with hydrophobic
polytetrafluroethylene (PTFE), pressed onto a nickel mesh (or nickel foam).

Question 11

What is Triple-phase boundary

Answer 11

(gas, electrolyte, and electrode) is the place where
electrochemical reaction takes place.

Question 12

Advantages of AFC

Answer 12

*Highest energy conversion efficiency (~70%) among all fuel cells
* Low cost: catalyst, electrolyte (KOH), and design
* Lower corrosivity, compared to an acidic environment
* Internal thermal management can be easily achieved by circulating the liquid
electrolyte
* Fast oxygen reduction kinetics

Question 13

Disadvantages of AFC

Answer 13

*Sensitive to CO2:
CO2 + 2OH- -> CO3^2- +H2O
CO3^2- + 2K+ -> K2CO3
* Leakage

Question 14

PEMC
Gas diffusion layer: ___
Catalysts: ____
Polymer Electrolytes:____
Bipolar Plates: ______

Answer 14

Gas diffusion layers: carbon support
Catalysts: Pt and its alloys; Pt/carbon black
Polymer electrolytes: Nafion and other perfluorinated sulfonic acid membranes
Bipolar plates: metal, carbonaceous materials, and composites