6.4 Metal-Air Battery
159
for aluminum-air batteries and fuel cells. Currently, the studies on perovskite
oxygen electrode catalysts have focused on the improvement of the preparation
method and research and development for new substituted elements to improve
catalytic performance. People can produce fine-grained, large-area perovskite
oxides by amorphous precursors, which greatly increase their catalytic activity.
It is currently a good method to prepare perovskite oxides.
(4) Cheap catalysts. Manganese dioxide oxidizer is a major representative, which
can be widely used in batteries with aqueous or non-aqueous electrolytes.
(5) AB 2 O 4 spinel oxide catalyst. In the unit cell shall there be 32 close-packed O
2−
ions, and 64 tetrahedral and 32 octahedral voids are occupied by metal ions.
The dehydration activity of spinel is closely related to the fraction of B ions in
the tetrahedral voids. The larger the fraction, the more acidic the surface of the
catalyst and greater the dehydration activity. Generally, aluminum-air batteries
do not use this catalyst.
(6) Other metal and alloy catalysts. Nickel is relatively inexpensive, and has high
corrosion resistance in anodic polarization conditions in alkaline electrolytes. At
the same time, the oxygen evolution efficiency of nickel is the highest in the metal
element, so nickel is conventionally used as an alkaline aqueous electrolytic
anode material. Nickel–iron, nickel–cobalt, and other alloy catalysts are also
often used. They have good catalytic activity and corrosion resistance.
(7) Composite catalysts. The two or more catalysts are compounded together to
better ameliorate the catalytic activity of the air electrode of the aluminum air.
6.4.3.2 Carbon Carrier
A good carrier can maximize the performance of the catalyst and reduce the amount
of catalyst. Conventional catalyst preparation methods, active carrier materials (such
as activated carbon, acetylene black, graphite, etc.) are prepared by mixing together.
The carrier material should have excellent adsorption properties, large surface area
as well as excellent electrical conductivity. The air electrode absorbs oxygen while
also adsorbing other gaseous impurities. Acetylene black with excellent electrical
conductivity, adsorption performance, and graphite with stable structure, and large
specific surface area, corrosion resistance, electrical conductivity, and fine particle
size can be used as carrier materials.
6.4.3.3 Adhesive
The electrode adhesive must have good viscosity, and the prepared electrode has a
certain mechanical strength, and at the same time, it must be hydrophobic. It can
construct a gas network channel, form a three-phase reaction interface, and has good
conductivity to reduce the ohmic polarization. The commonly used adhesive PTFE
(polytetrafluoroethylene), which is a non-polar adhesive, is very good in basicity, but
its viscosity is very low. PTFE forms a three-dimensional network when hot pressed
at about 300 °C, so that the active material does not fall off.
159
for aluminum-air batteries and fuel cells. Currently, the studies on perovskite
oxygen electrode catalysts have focused on the improvement of the preparation
method and research and development for new substituted elements to improve
catalytic performance. People can produce fine-grained, large-area perovskite
oxides by amorphous precursors, which greatly increase their catalytic activity.
It is currently a good method to prepare perovskite oxides.
(4) Cheap catalysts. Manganese dioxide oxidizer is a major representative, which
can be widely used in batteries with aqueous or non-aqueous electrolytes.
(5) AB 2 O 4 spinel oxide catalyst. In the unit cell shall there be 32 close-packed O
2−
ions, and 64 tetrahedral and 32 octahedral voids are occupied by metal ions.
The dehydration activity of spinel is closely related to the fraction of B ions in
the tetrahedral voids. The larger the fraction, the more acidic the surface of the
catalyst and greater the dehydration activity. Generally, aluminum-air batteries
do not use this catalyst.
(6) Other metal and alloy catalysts. Nickel is relatively inexpensive, and has high
corrosion resistance in anodic polarization conditions in alkaline electrolytes. At
the same time, the oxygen evolution efficiency of nickel is the highest in the metal
element, so nickel is conventionally used as an alkaline aqueous electrolytic
anode material. Nickel–iron, nickel–cobalt, and other alloy catalysts are also
often used. They have good catalytic activity and corrosion resistance.
(7) Composite catalysts. The two or more catalysts are compounded together to
better ameliorate the catalytic activity of the air electrode of the aluminum air.
6.4.3.2 Carbon Carrier
A good carrier can maximize the performance of the catalyst and reduce the amount
of catalyst. Conventional catalyst preparation methods, active carrier materials (such
as activated carbon, acetylene black, graphite, etc.) are prepared by mixing together.
The carrier material should have excellent adsorption properties, large surface area
as well as excellent electrical conductivity. The air electrode absorbs oxygen while
also adsorbing other gaseous impurities. Acetylene black with excellent electrical
conductivity, adsorption performance, and graphite with stable structure, and large
specific surface area, corrosion resistance, electrical conductivity, and fine particle
size can be used as carrier materials.
6.4.3.3 Adhesive
The electrode adhesive must have good viscosity, and the prepared electrode has a
certain mechanical strength, and at the same time, it must be hydrophobic. It can
construct a gas network channel, form a three-phase reaction interface, and has good
conductivity to reduce the ohmic polarization. The commonly used adhesive PTFE
(polytetrafluoroethylene), which is a non-polar adhesive, is very good in basicity, but
its viscosity is very low. PTFE forms a three-dimensional network when hot pressed
at about 300 °C, so that the active material does not fall off.