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J. Zhu et al.
external circuit to generate a discharge product (Li 2 O 2 ). The charge is the electrochemical decomposition process of the discharge products. An electrocatalyst is
required during the electrode reactions, such as an oxygen reduction electrocatalyst
during discharge and an oxygen evolution electrocatalyst during charging.
Lithium-air batteries have many advantages:
(1) Extremely high specific energy. As mentioned above, the battery does not store
the cathode active material, so it has a very high specific energy, about 11,000
Wh kg
−1 ;
(2) Environmentally friendly. Because the battery generates electricity in accordance with the electrochemical principle and does not go through the combustion process as the heat engine, it emits almost no nitrogen oxides and sulfur
oxides, reducing the pollution to the atmosphere;
(3) Quiet operation. The battery works relatively quietly and with low noise.
However, there are still many problems in the field of lithium-air batteries that
restrict its development.
(1) Lithium metal anode protection. When the battery is working in the air, the
organic electrolyte easily absorbs moisture in the air and causes corrosion of
the lithium metal negative electrode, resulting in a hidden safety hazard.
(2) Electrolyte stability. Intermediate products generated during the battery
discharge process easily react with the organic electrolyte, which results in the
formation of by-products, which in turn affects the battery’s charging characteristics. Furthermore, with the progress of the electrode reaction, the electrolyte
will be gradually consumed, which will affect the cycle stability of the battery.
Finally, because the battery works in an open environment, the electrolyte is
volatile, which also affects battery performance and even safety.
(3) Optimization of cathode materials. The discharge product of the battery is insoluble in the organic electrolyte and will be deposited in the porous positive electrode. When all the pores are blocked, the discharge of the battery is terminated.
Therefore, the optimization of the structure of the cathode material is also a key
issue.
(4) The electrode reaction kinetics is slow. More importantly, if no electrocatalyst is
used, the charge and discharge reaction of the battery is slow, and the polarization
phenomenon is very serious, which affects the cycle life of the battery. Because
the cathode reaction determines the charge–discharge performance and cycle
life of lithium-air batteries, the research on electrocatalysts can accelerate the
practical application of such batteries.
J. Zhu et al.
external circuit to generate a discharge product (Li 2 O 2 ). The charge is the electrochemical decomposition process of the discharge products. An electrocatalyst is
required during the electrode reactions, such as an oxygen reduction electrocatalyst
during discharge and an oxygen evolution electrocatalyst during charging.
Lithium-air batteries have many advantages:
(1) Extremely high specific energy. As mentioned above, the battery does not store
the cathode active material, so it has a very high specific energy, about 11,000
Wh kg
−1 ;
(2) Environmentally friendly. Because the battery generates electricity in accordance with the electrochemical principle and does not go through the combustion process as the heat engine, it emits almost no nitrogen oxides and sulfur
oxides, reducing the pollution to the atmosphere;
(3) Quiet operation. The battery works relatively quietly and with low noise.
However, there are still many problems in the field of lithium-air batteries that
restrict its development.
(1) Lithium metal anode protection. When the battery is working in the air, the
organic electrolyte easily absorbs moisture in the air and causes corrosion of
the lithium metal negative electrode, resulting in a hidden safety hazard.
(2) Electrolyte stability. Intermediate products generated during the battery
discharge process easily react with the organic electrolyte, which results in the
formation of by-products, which in turn affects the battery’s charging characteristics. Furthermore, with the progress of the electrode reaction, the electrolyte
will be gradually consumed, which will affect the cycle stability of the battery.
Finally, because the battery works in an open environment, the electrolyte is
volatile, which also affects battery performance and even safety.
(3) Optimization of cathode materials. The discharge product of the battery is insoluble in the organic electrolyte and will be deposited in the porous positive electrode. When all the pores are blocked, the discharge of the battery is terminated.
Therefore, the optimization of the structure of the cathode material is also a key
issue.
(4) The electrode reaction kinetics is slow. More importantly, if no electrocatalyst is
used, the charge and discharge reaction of the battery is slow, and the polarization
phenomenon is very serious, which affects the cycle life of the battery. Because
the cathode reaction determines the charge–discharge performance and cycle
life of lithium-air batteries, the research on electrocatalysts can accelerate the
practical application of such batteries.