6 Application of Oxygen Reduction Catalysts
241
process, the metal sodium loses electrons to form Na
+ , which is transmitted to the
positive carbon material through the electrolyte and combines with the reduced
oxygen element to generate stable Na 2 O 2 ; during charging, Na
+ in the electrolyte
near the negative electrode is reduced to metal Na, and Na 2 O 2 on the positive electrode is reduced to Na
+ and O 2 and released into the air. The efficiency of the charging
and discharging process can reach 80 ~ 90%. Compared with lithium materials, the
electrochemical process of Na 2 O 2 formed by the combination of sodium and oxygen
is more stable. Therefore, this new sodium-air battery has the advantages of high
stability and small voltage loss. The research results show that sodium materials also
have the prospect of being used as electrode materials for future new battery systems.
6.3 Secondary Lithium-Air Battery Application
This section first introduces the working principle of secondary lithium-air batteries,
then clarifies the process of oxygen reduction electrocatalysis during battery
discharge, focuses on several commonly used oxygen reduction electrocatalysts,
and discusses the electrocatalysts for this type of battery as well as the direction of
development.
6.3.1 Secondary Lithium-air Batter
The secondary lithium-air battery is a new type of energy storage and conversion
device. It converts the chemical energy in metallic lithium and oxygen into electrical
energy when discharging, and stores electrical energy by decomposing the discharge
products when charging. Lithium-air batteries differ from conventional batteries in
that their cathode reactive material oxygen (air) is not stored in the battery, but is
provided by the outside environment during discharge, so when it is working, the
oxygen needs to be continuously inserted into the battery [64, 65].
The electrochemical reactions during charge and discharge are as follows:
The anode process is:
Li ↔ Li
+
+ e
−
The cathode process is:
2Li
+
+ 2e
−
+ O 2 ↔ Li 2 O 2
(E 0 = 2.96 V vs. Li/Li
+
)
It can be seen that when the battery discharges, the cathode undergoes an oxygen
reduction reaction to generate superoxide ions (O
2−
2 ), which are combined with
lithium ions (Li
+ ) moving from the anode and electrons (e
− ) transported from the
241
process, the metal sodium loses electrons to form Na
+ , which is transmitted to the
positive carbon material through the electrolyte and combines with the reduced
oxygen element to generate stable Na 2 O 2 ; during charging, Na
+ in the electrolyte
near the negative electrode is reduced to metal Na, and Na 2 O 2 on the positive electrode is reduced to Na
+ and O 2 and released into the air. The efficiency of the charging
and discharging process can reach 80 ~ 90%. Compared with lithium materials, the
electrochemical process of Na 2 O 2 formed by the combination of sodium and oxygen
is more stable. Therefore, this new sodium-air battery has the advantages of high
stability and small voltage loss. The research results show that sodium materials also
have the prospect of being used as electrode materials for future new battery systems.
6.3 Secondary Lithium-Air Battery Application
This section first introduces the working principle of secondary lithium-air batteries,
then clarifies the process of oxygen reduction electrocatalysis during battery
discharge, focuses on several commonly used oxygen reduction electrocatalysts,
and discusses the electrocatalysts for this type of battery as well as the direction of
development.
6.3.1 Secondary Lithium-air Batter
The secondary lithium-air battery is a new type of energy storage and conversion
device. It converts the chemical energy in metallic lithium and oxygen into electrical
energy when discharging, and stores electrical energy by decomposing the discharge
products when charging. Lithium-air batteries differ from conventional batteries in
that their cathode reactive material oxygen (air) is not stored in the battery, but is
provided by the outside environment during discharge, so when it is working, the
oxygen needs to be continuously inserted into the battery [64, 65].
The electrochemical reactions during charge and discharge are as follows:
The anode process is:
Li ↔ Li
+
+ e
−
The cathode process is:
2Li
+
+ 2e
−
+ O 2 ↔ Li 2 O 2
(E 0 = 2.96 V vs. Li/Li
+
)
It can be seen that when the battery discharges, the cathode undergoes an oxygen
reduction reaction to generate superoxide ions (O
2−
2 ), which are combined with
lithium ions (Li
+ ) moving from the anode and electrons (e
− ) transported from the