Week 1 Understanding Different Battery Chemistry

1. To explain about the LCO, LMO, NCA, NMC, LFP and LTO type of lithium ion cells.

Battery:

      A Battery is an Electro chemical device. It is used to store the electrical energy. During discharging, chemical energy is converted in to electrical energy. When a battery is supplying electric power, its positive terminal is the cathode and its negative terminal is the 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 reactants to lower-energy products, and the free energy difference is delivered to the external circuit as electrical energy. 

There are two types of batteries, 

1. Primary cell - These batteries are one time use batteries and they cannot be recharged for further usage. Some of the applications are Watches, Calculators, Remote controllers etc.

2. Secondary cell - These batteries can be recharged and can be used for multiple times. During charging, electrical energy is converted into chemical energy. During discharging, chemical energy is converted in to electrical energy. Usedin various applications such as Mobile phones, Laptops, Electric vehicles etc.

Cathode:

* They are the positive electrodes of the cell.

* The cathode electrode is usually made up of,

* Layered Transition metal oxides which has high Capacity but high in cost and poor in safety.

* Spinel which has high power Density but poor in conductivity and stability. 

* Olivine which has less capacity but has long life and are high in safety.

Anode:

* They are the negative electrodes of the cell.

* The anode electrode is usually made up of Graphite and Hard Carbon

* The anodes are less in cost and high in stability and specific capacity.

Electrolyte:

* An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent

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

* Generally Lithium ion cells have electrolytes of Organic solvents such as, Ethylene carbonate, dimethyl carbonate, propylene carbonate and lithium salt as solute.

 Separator:

* Battery separators provide a barrier between the anode (negative) and the cathode (positive) 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.

Li-ion battery:

 * The battery is made up of an anode, cathode, separator, electrolyte, and two current collectors (positive and negative), the anode and cathode store the lithium.

* The electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa through the separator.

* The movement of the lithium ions creates free electrons in the anode which creates a charge at the positive current collector.

* The electrical current then flows from the current collector through a device being powered (cell phone, computer, electric motor etc.) to the 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 electrons from one side to the other.

 There are some types of lithium ion cells based on their chemical compositions and they are,

1. Lithium cobalt oxide-LiCo02 (LCO)

2. Lithium Manganese Oxide - LiMn204 (LMO)

3. Lithium Nickel Cobalt Aluminum Oxide - LINICOAIO2 (NCA)

4. Lithium Nickel Manganese Cobalt Oxide - LiMnC002 (NMC)

5. Lithium Iron Phosphate-LiFePo4 (LFP)

6. Lithium Titanium Oxide - LiTiO2 (LTO)

1. Lithium cobalt oxide-LiCo02 (LCO):

Lithium cobalt oxide (LCO) batteries have high specific energy but low specific power. This means that they do not perform well in high-load applications, but they can deliver power over a long period.

LCO batteries were common in small portable electronics such as mobile phones, tablets, laptops, and cameras. However, they are losing popularity to other types of lithium batteries due to the high cost of cobalt and concerns around safety.

The key benefit to LCO batteries is their high specific energy. This allows them to deliver power over a relatively long period under low-load applications.

* It is also known 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. Cobalt is quite expensive. LCO batteries also have low thermal stability, which leads to safety concerns.

                                               

2. Lithium Manganese Oxide - LiMn204 (LMO):

* The first commercial lithium-ion cells made with lithium manganese oxide as a cathode material were produced in 1996 by Moli Energy.

* Lithium manganese oxide batteries are preferred 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 also possible to use lithium manganese oxide batteries to power laptops and electric powertrain.

                                         

3. Lithium Nickel Cobalt Aluminum Oxide - LINICOAIO2 (NCA):

* Lithium nickel cobalt aluminum oxide batteries are also called NCA batteries, and are becoming increasingly important in electric powertrains and in grid storage.

* NCA batteries are not common in the consumer industry, but are promising for the automotive industry.

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

                                               

4. Lithium Nickel Manganese Cobalt Oxide - LiMnC002 (NMC):

* It is also known as lithium manganese cobalt oxide or NMC batteries, include a cathode made of a combination of nickel, manganese and cobalt.

* Like other lithium-ion battery varieties, NMC batteries can have either a high specific energy density or a high specific power. They cannot have both properties.

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

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

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

                                           

 5. Lithium Iron Phosphate-LiFePo4 (LFP):

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

* Durability and a long lifecycle - fully charged batteries can be stored with little change to the total lifespan of the battery's 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 has less energy than other types of lithium batteries.

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

                                          

6. Lithium Titanium Oxide - LiTiO2 (LTO):

*Finally, lithium titanate, also known as li-titanate, is a class of battery that allows for ever-increasing applications.

* The main advantage of the li-titanate battery is its remarkably fast recharge time.

* Currently, manufacturers 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 vehicles efficiently. Even so, the density of lithium titanate batteries is still higher than other non-lithium-ion batteries.

                                           

Chemical reactions of LCO, LMO, NCA, NMC, LFP and LTO type of lithium ion cells:

Chemical Name	At cathode	At Anode	Overall reaction

Thus the chemical reactions and thier characteristics of LCO, LMO, NCA, NMC, LFP and LTO type of lithium ion cells are explained along with the chemical equations.