Vaporized Methanol Fuel Cells

Vaporized Methanol Fuel Cells

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Vaporized Methanol Fuel Cells

A Brief History of Fuel Cells

In 1839 Sir William Grove invented the fuel cell . He produced electricity by combining hydrogen and oxygen at electrodes that were separated by an aqueous liquid acid electrolyte . [1] Subsequently throughout the 19th and 20th centuries , a variety of researchers investigated fuel cell reactions for the conversion of chemical energy into electrical energy . [2] The first practical application of fuel cells occurred during the Apollo space program from 1960

to 1965 . [1] Those fuel cells provided both drinking water and electricity . In 1970 Kordesch built a car that operated using the combination of an alkaline fuel cell and a lead acid battery . Recently environmental pollution issues have been the driving force for the development of fuel cells [3]

Fuel Cells - Definition , Composition , and Operating Principles

A fuel cell is a device that generates electricity and produces heat from an electrochemical reaction using suitable catalysts . The most common fuel used in fuel cells is hydrogen . It is used in combination with oxygen to produce electricity based on the following overall chemical reaction [4]

H2 1 /2 O2 ? H2O

In general , a fuel cell assembly can be divided into five layers as shown in figure 1 . On each side of the five layers there are flow channels that are usually machined into solid graphite plates . The anode side of the fuel cell includes the anode-backing layer (anode diffusion layer ) and the anode catalyst layer . The cathode side includes the cathode backing layer (cathode diffusion layer ) and the cathode catalyst layer . The electrolyte layer separates the anode side from the cathode side of the fuel cell . If the electrolyte is a membrane , the five layers are called a Membrane Electrode Assembly (MEA ) [5]

Hydrogen or a hydrocarbon-containing fuel such as methanol is supplied to the anode side and electrochemically oxidized . Oxygen or air is supplied to the cathode side and electrochemically reduced . The anode reaction that occurs at the anode side (anode catalyst layer ) produces protons and electrons . [6] Electrons flow through (a ) the electronically conducting anode material , to (b ) the external circuit that contains an electrical load , to (c ) the cathode side . The protons travel through a specific electrolyte (such as a membrane , to (d ) meet the electrons and oxygen at the cathode side , where the cathode reaction occurs [1]

Each of the fuel cell layers has individual characteristics . The backing layers in the anode and the cathode have several functions . They are the thickest of the layers and they provide the mechanical strength for the MEA that includes the other layers of the fuel cell . They are made from either carbon or carbon cloth composed of fibers that create a porous structure . The channels containing the flowing reactants are interspersed with "lands , or regions of the backing layers that are not exposed to reactants . The porous structures of the backing layers permit the reactants to diffuse in a direction perpendicular to the...