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J. Zhu et al.
electrode, thus blocking the O 2 mass transfer channel of the air electrode. Moreover,
the currently developed organic electrolyte (format reagent) suitable for magnesium
electrode is a volatile substance, so volatilization on one side of the air electrode will
be unavoidable. All these affect the performance of organic magnesium-air battery.
In the water-based magnesium-air battery, the main problems currently faced
are the self-corrosion of Mg in aqueous solution, H 2 evolution, and the activation
and passivation of magnesium alloy. Because it affects the stability, reactivity and
energy utilization efficiency of magnesium anode in aqueous solution, and determines the performance of the battery. In order to solve these problems, Korean
scientists have used a variety of substances to change the chemical composition of
the magnesium anode, while improving the air cathode to improve the reaction efficiency and speed. Finally, the discharge specific energy of the team’s magnesium-air
battery was doubled compared with that of the traditional battery. Moreover, the
battery only needed 10 min to charge and only needed mechanical replacement of
the magnesium plate and brine electrolyte. However, there are still many difficulties to overcome before the commercialization of magnesium-air battery. At present,
the fuel cost of magnesium-air battery cars is three times that of gasoline-powered
cars. Once battery technology and Mg(OH) 2 recovery technology are developed, the
later cost is expected to be greatly reduced, so commercialization of magnesium-air
electric vehicles can still be expected.
(2) Iron-air battery [62]
The School of Arts and Sciences of the University of Southern California has developed an iron-air battery, which is low in cost, environmentally friendly and rechargeable, and can be used for energy storage of solar energy and wind power plants in
rainy days. This iron-air battery uses iron as the negative electrode, air electrode
as the positive electrode, and aqueous solution as the electrolyte. The discharging
process of the battery is similar to iron rusting, and the battery developed at present
has the capability of storing 8–24 h of energy. Iron-air battery faces a great problem
in the research and development process: hydrogen evolution corrosion reaction of
iron in the battery, which will lose about 50% of battery energy and greatly reduce
battery efficiency. The research team managed to reduce the energy loss to 4% by
adding a very small amount of bismuth sulfide to the battery. Bismuth can restrain
the waste of energy in the process of hydrogen production. Very little bismuth sulfide
will not affect the environmental protection characteristics of the battery, but it can
improve the efficiency of the iron-air battery by about 10 times compared with the
previous similar batteries.
(3) Sodium-air battery [62, 63]
The Karlsruhr Research Center of Giesen University in Germany and researchers
from BASF Company cooperated to replace the most commonly used metallic lithium
as electrode material with metallic sodium. A secondary sodium-air battery was
designed and developed. The theoretical specific energy of the sodium-air battery
can reach 1600 W/kg and the discharge voltage is 2.2 V. During the battery discharge
J. Zhu et al.
electrode, thus blocking the O 2 mass transfer channel of the air electrode. Moreover,
the currently developed organic electrolyte (format reagent) suitable for magnesium
electrode is a volatile substance, so volatilization on one side of the air electrode will
be unavoidable. All these affect the performance of organic magnesium-air battery.
In the water-based magnesium-air battery, the main problems currently faced
are the self-corrosion of Mg in aqueous solution, H 2 evolution, and the activation
and passivation of magnesium alloy. Because it affects the stability, reactivity and
energy utilization efficiency of magnesium anode in aqueous solution, and determines the performance of the battery. In order to solve these problems, Korean
scientists have used a variety of substances to change the chemical composition of
the magnesium anode, while improving the air cathode to improve the reaction efficiency and speed. Finally, the discharge specific energy of the team’s magnesium-air
battery was doubled compared with that of the traditional battery. Moreover, the
battery only needed 10 min to charge and only needed mechanical replacement of
the magnesium plate and brine electrolyte. However, there are still many difficulties to overcome before the commercialization of magnesium-air battery. At present,
the fuel cost of magnesium-air battery cars is three times that of gasoline-powered
cars. Once battery technology and Mg(OH) 2 recovery technology are developed, the
later cost is expected to be greatly reduced, so commercialization of magnesium-air
electric vehicles can still be expected.
(2) Iron-air battery [62]
The School of Arts and Sciences of the University of Southern California has developed an iron-air battery, which is low in cost, environmentally friendly and rechargeable, and can be used for energy storage of solar energy and wind power plants in
rainy days. This iron-air battery uses iron as the negative electrode, air electrode
as the positive electrode, and aqueous solution as the electrolyte. The discharging
process of the battery is similar to iron rusting, and the battery developed at present
has the capability of storing 8–24 h of energy. Iron-air battery faces a great problem
in the research and development process: hydrogen evolution corrosion reaction of
iron in the battery, which will lose about 50% of battery energy and greatly reduce
battery efficiency. The research team managed to reduce the energy loss to 4% by
adding a very small amount of bismuth sulfide to the battery. Bismuth can restrain
the waste of energy in the process of hydrogen production. Very little bismuth sulfide
will not affect the environmental protection characteristics of the battery, but it can
improve the efficiency of the iron-air battery by about 10 times compared with the
previous similar batteries.
(3) Sodium-air battery [62, 63]
The Karlsruhr Research Center of Giesen University in Germany and researchers
from BASF Company cooperated to replace the most commonly used metallic lithium
as electrode material with metallic sodium. A secondary sodium-air battery was
designed and developed. The theoretical specific energy of the sodium-air battery
can reach 1600 W/kg and the discharge voltage is 2.2 V. During the battery discharge