Week 1 Understanding Different Battery Chemistry

QUESTION :

1.Prepare a table which includes materials & chemical reactions occurring at the anode and cathode of LCO, LMO, NCA, NMC, LFP and LTO type of lithium ion cells.Give your detailed explanation on it

2.Compare the differences between each type of Li+ion batteries based on their characteristics

SOLUTION : BATTERY :

• A battery is a device consisting of one or more electrochemical cells with external connections for powering electrical devices such as flashlights, mobile phones and electric cars.
• When a battery is supplying electric power , its positive terminals is the cathode and its negative terminals is anode.
• The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal.
• When a battery is connected to an external electric load, a redox reaction converts high energy reactancts to lower energy products, and the free energy difference is delivered to the external circuit as electrical energy.
• There are two types of batteries.
• Primary cell : These batteries are one times use batteries and they cannot be recharged for further usage.
• Secondary cell : These batteries can be recharged and can be used for multiple times.

LITHIUM ION CELL :

The lithium ion batteries are secondary type of batteries which can be recharged for further usage.

The lithium ion cells have four main components in it and they are.

cathode, Anode , ELECTROLYTE , SEPERATOR.

1) CATHODE : They are the positive electrodes of the cell.

The cathode electrode is usually made up of.

LAyered transmission metal oxides has high capacity but high in cost and poor in safety..

Spinels have high power density but poor in conductivity and stability.

Olivines are less capacity but has long life and are high in safety.

2) ANODE : They are negative electrode of the cell.

The anode lectrode is usually made up of Graphite, hard carbon these anodes are less in cost and high in stability and specific energy.

3) ELECTROLYTE : An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvant.

The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent.

Generally, lithium ion cells have electrolyte of organic solvent such as Ethylene carbonate, Dimethyl carbonate, propylene carbonate and lithium salt as solute.

4) SEPERATOR :

Battery seperators provide a barrier between the anode and the cathode. while enabling the exchange of lithium ions from one side to the other.

They are materials that conducts ions but they do not conduct the electrons through them.

Li-ion cells use polyolefin as a separator. THis material has excellent mechanical properties, good chemical stability and is low cost as well.

WORKING OF LITHIUM ION CELLS :

• The battery is made up of an anode, cathode, separator, electrolyte, and two current collectors, the anode and cathode store the lithium.
• The electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa through thhe separator.
• The movement of the lithium ions creates free electrons in th eanode which create a charge at the positive current collector.
• The electric current then flows from from the current collector through a device being powered to negative current collector. The separator blocks the flow of electrons inside the battery.
• While the battery is discharging and providing an electric current , the anode releases lithium ions to the cathode, generating a flow of electron from one side to the other.
• When charging, the opposite happens where lithium ions are released by the cathode and received by the anode.
• This is the working principle of a lithium ion battery.

VARIOUS TYPES OF LITHIUM ION CELL :

1. Lithium cobalt oxide - licoO2 ( LCO)

This is also know as lithium cobaltate or lithium ion cobalt batteries, lithium cobalt oxide batteries are made from lithium carbonate and cobalt.

They have a cobalt oxide cathode and use graphite carbon as their anode material, during discharge , lithium ions move from anode to cathode with the flow reversing when the battery is charging.

This type of battery has some drawbacks, including a relatively short battery life and limited specific power, additionally these batteries are not as safe as other types.

2. LITHIUM MANGANESE OXIDE - liMn204 (LMO)

The first commercial lithium ions cells made with lithium mannganese oxide as a cathode material were produced in 1996 by moli energy.

Lithium manganese oxide batteries are notable for their high temperature stability and are also safer than other lithium ion battery types.

For this reason, they are often used in medical equipment and devices, but they may also be used in power tools, electric bikes and more.

It is possible to use lithium manganese oxide batteries to power laptops and electric powertrain cars.

3 . LITHIUM NICKEL COBALT ALUMINIUM OXIDE - LiNiCoAlO2 (NCA)

Lithium nickel cobalt aluminium oxide batteries are also called NCA batteries and are becoming increasingly important in electric powertrain and in grid storage.

NCA batteries are not common in the consumer industry but are promising for the automative industry.

NCA batteries provide a high energy option with a good lifespan, but they are not as safe as they could be comared to other lithium ion battery types and are quite costly.

4. LITHIUM NICKEL MANGANESE COBALT OXIDE - LiMnCoO2 (NMC)

Also know as lithium manganese cobalt oxide or NMC batteries, include a cathode made of a combination of nickel, manganese and cobalt.

Like other liyhium ion batteries varieties, NMC batteries can have either a high specific energy density or a high specific power.

This battery type is most common in power tools and in powertrain for vehicles.

The cathode combination ratio is usually 60% nickel, 20%manganese and 20%cobalt. This means that the raw material cost is lower than its for other lithium ion battery options as cobalt can be quite expensive.

These batteries may come down in price further in future, as some battery makers are planning to switch their battery chemistry to a higher % of nickel, so that they can use less cobalt.

This battery type is commonly preferred for electric vehicles due to its very low self heating rate.

5. LITHIUM IRON PHOSPHATE - BLiFeP04 (LFP).

Lithium iron phosphates batteries , also know as li- phosphate batteries, use phosphate as a cathode. They benefit from low resistance properties, which enhance their safety and thermal stability.

Other benefits include durability and a long lifecycle, fully charged batteries can be stored with little change to the total lifespan of the batterys charge.

Li- phosphate batteries are often the most cost- effective option as well when their long battery life is taken into consideration. However, the lower voltage of the li-phosphate battery means that it has less energy than other types of lithium batteries.

Accordingly, these batteries are often used in electric motorcyle as well as other applications that need a long lifecycle and significant safety.

6. LITHIUM TITANIUM OXIDE - LiTiO2 (LTO)

Finally, lithium titanate also know as li-titanate is a class of batteries that allows for ever increasing applications the main advantage of the li- titanate battery is its remarkably fast recharge time.

Currently, manufactures of electric vehicles and bikes use li- titanate batteries and there is potential for this type of battery to be used in electric buses for public transportation.

However, these batteries have lower inherent voltage or lower energy density than other lithium ion battery varieties, which can present issues with powering vehicle effeciently. Even so the density of lithium titanate batteries is still higher than other non liyjium ion batteries which is a plus.