LITHIUM BATTERY

LITHIUM BATTERY
Lithium battery is a solid state battery because instead of using liquid or a paste electrolyte, solid electrolyte is used.

Construction
The lithium battery consists of a lithium anode and a TiS2 cathode. A solid electrolyte, generally a polymer, is packed in between the electrodes. The electrolyte (polymer) permits the passage of ions but not that of electrons.

Working (Discharging)
When the anode is connected to cathode, lithium ions move from anode to cathode. The anode is elemental lithium, which is the source of the lithium ions and electrons. The cathode is a material capable of receiving the lithium ions and electrons.
At anode: Li(s) → Li+ + e¯
At cathode: TiS2 (s) + e¯ →TiS2¯

Overall reactions
Li(s) + TiS2 (s) → Li+ + TiS2¯
Li+ + TiS2¯ → LiTiS2

Recharging the Battery
The lithium battery can be recharged by supplying an external current, which drives the lithium ions back to the anode. The overall reaction is

LiTiS2 → Li+ + TiS2¯
This cell is rechargeable and produces a cell voltage of 3.0V.

Other types of secondary Lithium Batteries
i. Li/MnO2
ii. Li/V2O5
iii. Li/MoO2
iv. Li/Cr3O8

Advantages of Lithium battery
It is considered to be cell of the future because
1. Its cell voltage is high, 3.0 V.
2. Li being a light-weight metal, only 7g (1 mole) material is required to produce 1 mole of
electrons.
3. Since Li has the most negative E° value, it generates a higher voltage than the other types
of cells.
4. All the constituents of the battery are solids and there is no risk of leakage from the battery.
5. This battery can be made in a variety of sizes and shapes.

Lithium - Sulphur

Lithium-sulphur battery is a rechargeable battery. Here the anode is Lithium and Sulphur is the electron acceptor. The electron from Li is conducted to S by a graphite cathode. β-Alumina (NaAl11O17) is used as the solid electrolyte, which separates anode and liquid sulphur.
This solid electrolyte allows the Li+ ions to migrate to equalize the charge, but will not allow the big poly sulphide product ions.
This battery is operated at high temperatures as Li and S should be in their molten states.

Various reactions
The Various electrode reactions are
At anode: 2Li → 2Li+ + 2e¯
At cathode: S + 2e¯ → S2¯
Over all reactions: 2Li + S→ 2Li+ S2¯
The S2¯ ions, formed, react with elemental sulphur to form the polysulphide ion.

S2¯+ nS → [Sn +1]2¯
The direct reaction between Li and S is prevented by the alumina present in the cell.

Advantages of Li-S battery

1. Li-S battery has light weight unlike the lead acid battery.
2. It possesses a high energy density.
3. It is used in electric cars.