Proton Exchange Membrane Fuel Cells – Fundamentals and Applications

質子交換膜燃料電池 ---原理與應用

C. W. Lin•Department of Chemical Engineering

•National Yunlin University of Science & Technology

Fuel cell technology

A Dream

, Challenge

Or A Necessity

Fuel cell as energy converter

Chemical energy of

the fuels

Electrical energy conversion

Thermal energy conversion

Mechanical energy conversion

H2

H2

O2

O2

H+

H+

H+

H+

-

-

-

- OH

H

OH

H

National Yunlin University of Science & TechnologyFunctional Polymer Lab.

A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water and heat.

High energy-conversion efficiency

Thermodynamic efficiency for fuel cells and Carnot efficiency for heat engines

What is a fuel cell?

Proton and hydroxyl conducting fuel cells

Modular design

Fuel cells for different scale applications

Small transportation

Can we apply small technologies to become more sustainable?

DMFC Application: Portable Power

DMFC: Working principle

CH3OH+H2OCO2+6H++6e

Anode

O2+4H++4e 2H2O

Cathode

CH3OH O2

H2O

e

D

R

Y

H2O H2O

H+ transport

H+ transport

e

H+ transport

fuel crossover

fuel crossover

CO2

Catalyst poisoning

Pt-CO

DMFC: Problems and possible solutions

Methanol crossoverHybrid membranes, nanocomposites, etc

Catalyst poisoning (Pt-CO)Better complex catalyst (Pt-X), higher temperature (>120°C)

Slow “water shift reaction” (CH3OH+H2O CO2+6H+

+6e) below ~100 °CBetter complex catalyst, higher temperature

But the higher the temperature, the worse the water balance in membrane

Water-free membranes?

PEMFC: Water balance in membrane

Water balance in polymer membrane.

H2 2H++2e

Anode

O2+4H++4e 2H2O

CathodeH+ transport

H2O diffusion

Electro-osmotic dragH+(H2O)

H2O diffusion

H+ transport

H2 O2

H2O

e e

D

R

Y

W

E

T

H2O H2O

MEA 組成示意圖

Currently Used Proton ExchangeMembrane(PEM)-Nafion