Lithium‒ion battery (LIB) (or) Lithium‒ion cell

Lithium‒ion battery (LIB) (or) Lithium‒ion cell - SECONDARY BATTERY

Lithium‒ion battery is a secondary battery. As in lithium cell, it does not contain metallic lithium as anode. As the name suggests, the movement of lithium ions are responsible for charging and discharging.

Components

Lithium‒ion cell has the following three components.

• A positive electrode (Layers of lithium‒metal oxide) (cathode)

• A negative electrode (Layers of porous carbon) (anode)

• An electrolyte (Polymer gel) (separator)

Description

Cathode: Lithium‒cobalt oxide (LiCoO₂) Layers

Anode: Graphite (Porous carbon) layers

Electrolyte: Polymer gel (organic solvent)

Construction

The positive electrode is typically made from a layers of chemical compound called lithium‒cobalt oxide (LiCoO₂).

The negative electrode is made from layers of porous carbon (C) (graphite).

Both the electrodes are dipped in a polymer gel electrolyte (organic solvent) and separated by a separator, which is a perforated plastic and allows the Li⁺ ions to pass through.

Working

Charging

During charging, Li⁺ ions flow from the positive electrode (LiCoO₂) to the negative electrode (graphite) through the electrolyte. Electrons also flow from the positive electrode to the negative electrode through the wire. The electrons and Li⁺ ions combine at the negative electrode and deposit there as Li.

LiCoO₂ + C → Li_1‒xCoO₂ + CLi_x

Discharging

During discharging, the Li⁺ ions flow back through the electrolyte from negative electrode to the positive electrode. Electrons flow from the negative electrode to the positive electrode through the wire.

The Li⁺ ions and electrons combine at the positive electrode and deposit there as Li.

Li_1‒xCoO₂ + CLi_x → LiCoO₂ + C

Advantages and Disadvantages of lithium‒ion batteries

Advantages

1. It is light in weight.

2. Rate of self‒discharge is low.

3. Have higher energy density than other rechargeable batteries.

4. Have a greater number of charge and discharge of cycles.

5. Operates at higher voltage (3.7 V)

6. No liquid electrolyte is used.

7. Easy maintenance.

Disadvantages

1. They are expensive.

2. Availability of lithium is difficult.

3. Difficulties in transportation.

4. Improper disposal leads to environment contamination.

5. It is temperature‒sensitive battery and explode at high temperature.

Applications

1. It is used in portable electronic devices like cellular phones, digital cameras, tablets and laptop computers.

2. It is used in biomedical implantable devices such as pace makers.

3. It is currently used in most electric vehicles because of their high energy per unit mass.