1. Overview of Lithium-Air (Lithium-Oxygen) Batteries
By: Dixit Chhatbar and Tak Hung Kwan

2. Overview Overall structure of Li-Air (Li-O2) battery
Electrochemistry of Li-Air (Li-O2) battery
Energy Density of Li-Air (Li-O2) battery
Types of Electrolyte used in Li-Air (Li-O2) battery and their strengths and weaknesses
Weaknesses of the electrodes used in Li-Air (Li-O2) battery

3. General Information
Lithion-ion batteries have been the most suitable for utility storage
Energy Density
Lithium-ion batteries
~400 Wh-kg-1
Lead-acid batteries
30-40 Wh-kg-1
Nickel-cadmium batteries
40-60 Wh-kg-1
Within Li-ion batteries, lithium-air (lithium-oxygen) batteries attracts the most attention

4. Structure of Li-Air (Li-O2) Battery

5. Electrochemistry of Li-Air (Li-O2) Battery
Anodic reaction
Li → Li+ + e⁻
Cathodic reaction
O2 + 2e⁻ + 2Li+ → Li2O (non-aqueous)
4Li+ + 4OH- → 4Li + O2 + 2H2O (aqueous and hybrid non-aqueous/ aqueous)
2Li+ + 2O- → Li2O (solid-state)

6. Energy Density of Li-Air (Li-O2) Battery
Non-aqueous Li-Air (Li-O2) battery
At Voc = 2.96V
11,680 Wh-kg-1 for the charged state
Closed to energy density of gasoline (13,000 Wh- kg-1)
10 times higher than other Li-ion battery
3,460 Wh-kg-1 for the discharge state

7. Energy Density of Li-Air (Li-O2) Battery

8. Energy Density of Li-Air (Li-O2) Battery
Aqueous Li-Air (Li-O2) Battery
At VOC = 3.0V
1,910 Wh-kg-1 for the charged state
5 times higher than Li-ion batteries
2,004 Wh-kg-1 for the discharge state

9. Types of Electrolytes in Li-Air (Li-O2) Battery
There are four types of electrolytes currently being used in lithium-air (lithium- oxygen) batteries which are:
Non-aqueous
Aqueous
Hybrid non-aqueous/ aqueous
Solid state.

10. Non-aqueous Li-Air (Li-O2) Battery
Composed of an electrode made of lithium metal on one side
Air electrode on the other side- a saturated non-aqueous electrolyte made up of lithium salt that is dissolved in non-aqueous solvent
A liquid electrolyte in the middle
Strength
high ionic conductivity, good chemical and electrochemical stability, high boiling point, low vapor pressure, and high oxygen solubility, high specific energy density(charged and discharged)
Weakness
stability issues for both the solvent and the lithium salt

11. Aqueous Li-Air (Li-O2) Battery
Anode- lithium metal
Cathode- a porous air electrode
Elctrolyte- lithium salt and water as the aqueous solvent in the middle
In this battery, the lithium metal needs to be protected by placing a solid-state lithium ion conducting membrane on the metal
This is done as to get rid of the blockage of the porous air electrode by the discharge product that the non-aqueous and solid-state lithium-air batteries have with the soluble LiOH.
Weakness
low specific energy density and low stability towards the solid-state membrane

12. Hybrid non-aqueous/ aqueous Li-Air (Li-O2) Battery
Anode- a non-aqueous electrolyte
Cathode- an aqueous electrolyte
Electrolyte- a non-aqueous electrolyte membrane
Strength
Increases the lithium ion conductivity and allow the lithium and the solid electrolyte membrane to be in no direct contact.
Weakness
Similar to weaknesses of the aqueous lithium-air

13. Solid state Li-Air (Li-O2) Battery
The anode and the cathode are same as that of non-aqueous lithium-air but the electrolyte is solid-state lithium ion conducting membrane
Strength
High lithium ion conductivity, very low diffusion coefficient for other species such as O2 and H2O, and a high resistance towards the direction reaction with the lithium metal
Weakness
Lies at the solid-state lithium ion membrane, which causes a low stability towards the electrolyte and the lithium metal

14. Weaknesses of Air Electrode of Li-Air (Li-O2) Battery
The reaction pathways among oxygen, lithium ions, and the electrons for the lithium-air (lithium-oxygen) batteries needs to be maintained as long as possible in order to have a high practical capacity.
Also they use carbon materials as the catalysts, instability occurs, thus, minimizing the cycling life for the air electrodes.
Also carbon materials are used as catalysts for the air electrode, carbon dioxide (CO2) gas occurs during the reactions, where CO2 gas can further pollute the environment, thus, increasing the danger of global warming.

15. Weaknesses of Lithium Electrode of Li-Air (Li-O2) Battery
Oxygen and other side products have caused the reactions between the lithium metal anode and the electrolyte to be extremely complicated, thus, creating a thick passivation layer on the lithium surface.
Increases the lithium ion transport resistance, leading to the decay of the battery performance and to the battery failure.

16. But I’ll use it anyhow because!!!
The battery’s high specific energy density, these lithium-air (lithium- oxygen) batteries have been considered as the possible power sources for the electric vehicles (EVs).
These batteries can serve as the solar energy storage for PV utility systems.