Li-ion batteries are a type of rechargeable batteries that are important in mobile systems. Li-Ion batteries are one of the most commonly used batteries in the automotive industry. How do Li-ion batteries work?
You could find those batteries in mobile phones, MP3 players, laptops, and other electronic devices.
Lithium-ion battery for cars: Lithium-ion cells stacked together to form high voltage batteries in electric vehicles nowadays.
What are cells and batteries?
A cell is a basic electrochemical unit that contains electrodes (anode and cathode) separator, and electrolytes.
Single-cell is not capable of supplying a large amount of electric energy to the appliances. So they are connected to form a battery pack.
A battery or battery pack is a collection of cells or cell assemblies, with housing, electrical connections, and possibly electronics for control and protection
The lithium-ion cells are connected together to make 12V, 36V, and even higher voltage (400V) battery packs.
The main components of a cell are
Intercalation is the reversible inclusion of molecules into the material with a layered structure. It further expands the Van Der Waals gap and results in a week bonding.
What happens to the lithium-ion battery when it charges and discharges? Here is a schematic diagram of a Li-ion battery.
The chemical reactions happen at anode and cathode are as follows.
The Li+ ions cross the semipermeable membrane and electrons travel from the anode to cathode through the external load connected. Conventionally, the direction of current is opposite to the direction of electrons. So the current flows from the cathode to anode.
The chemical reactions happens during discharging are
When we connect the charging equipment to the battery (Anode to -ve and Cathode to +ve terminal) the battery starts charging. The voltage of the external power supply equipment must be higher than the cell voltage to get it charged.
The overall reaction happens in the Lithium ion battery are as follows. It is a reversible reaction.
Left to right happens during discharging and right to left happens during charging of Li-ion battery.
The following are the main advantages of lithium-ion batteries.
The size of the Li-ion battery would be less compared to other battery technologies to store the same amount of energy.
So, Li-ion batteries are lighter and smaller.
The nominal voltage of Li-Ion cell is higher than that of Lead-acid, NiMh, and NiCd batteries. It is around 3.6 to 3.85 V
Li-ion batteries won’t self-discharge much. A lithium-ion battery pack loses only about 5 percent of its charge per month, compared to a 20 percent loss per month for NiMH batteries.
They have no memory effect, which means that you do not have to completely discharge them before recharging, as with some other battery chemistries. Ni-Cd batteries have the memory effect that results in issues in charging and discharging.
Lithium-ion batteries can handle a few thousands of charge/discharge cycles. Other battery technologies does not last this long.
Extreme care is required for a lithium ion battery pack. Let’s list out a few disadvantages of Li-ion batteries.
They are extremely sensitive to high temperatures. Heat causes lithium-ion battery packs to degrade much faster than they normally would.
As a result of the high-temperature sensitivity of Li-ion batteries, thermal management is highly important in an electric vehicle that uses Li-ion batteries.
Click To TweetA battery management system must be used to manage the Li-ion battery. It makes them even more expensive.
There is a little chance of thermal runaway in Li-ion batteries. A short circuit of a cell generates more heat and adjacent cells get damaged.
A thermal runaway is the most common electric car fire incident. Sometimes it happened very slowly.
You may read: Are electric cars safe in accidents?
Lithium-ion batteries are now common in many electronics systems. They are light, and smaller batteries compared to other battery technologies.
We have discussed the chemistry, how do li-ion batteries work, and the advantages and disadvantages of Li-ion batteries.
