Week 1 Understanding Different Battery Chemistry

Aim:

* To make a study and understand the electrochemistry of different types of lithium-ion cells.

Questions:

1. Prepare a table that includes materials & chemical reactions occurring at the anode and cathode of LCO, LMO, NCA, NMC, LFP, and LTO types of lithium-ion cells.

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 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.
2. Secondary cell- These batteries can be recharged and can be used multiple times.

Lithium-ion Cell:

* Lithium-ion batteries are a secondary type of battery that can be recharged for further usage.

* The Lithium-ion cells have four main Components in it and they are,

(i) Cathode

(ii) Anode

(iii) Electrolyte

(iv) Seperator

(i) Cathode:

* They are the positive electrodes of the cell.

* The cathode electrode is usually made up of,

1. Layered Transition metal oxides - Has high Capacity but high in cost and poor in safety.
2. Spinels - High power Density but poor conductivity and stability.
3. Olivines - Lees capacity but has a long life and are high in safety.

(ii) Anode:

* They are the negative electrodes of the cell.

* The anode electrode is usually made up of,

1. Graphite
2. Hard Carbon, these anodes are less in cost and high in stability and specific capacity.

(iii) 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.

(iv) 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 conduct ions but they do not conduct the electrons through them.

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

Working of Lithium-ion cell:

* 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.

* 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.

Types of Lithium-ion batteries:

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

1. Lithium cobalt oxide - LiCoO2 (LCO)

* 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 relatively short battery life and limited specific power. additionally, these batteries are not as safe as other types.

2. Lithium Manganese Oxide - LiMn2O4 (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 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 also 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 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 - LiMnCoO2 (NMC)

* 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, however, 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, as cobalt can be quite expensive.

* These batteries may come down in price further in the 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 - 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.

Other benefits include 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 means that it 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, which is a plus.

Li-ion cell Type	Cathode	Anode	Electrolyte	Seperator	Overall Reaction at Cathode & Anode	Mobile phones, laptops and digital cameras	Application
LCO	Graphite	Lithium Cobalt Oxide	Ethylene Carbonate + Li salt	Polyolefin	Li1-xCoO2(s) + x Li+ + x e- → LiCoO2(s)	Power tools, medical devices, electric powertrains	Mobile phones, laptops, and digital cameras
LMO	lithium manganese oxide	Graphite carbon	Methyl carbonate + Li salt	Polyolefin	Mn2+ + 2 LiC6 → Mn + 2 Li++ graphite	Medical devices, industrial, electric powertrain (Tesla)	Power tools, medical devices, electric powertrains
NCA	Comprised of Nickel cobalt & Aluminium	Graphite carbon	Propylene carbonate + Li salt	Polyolefin	Li(1−x)NiO2 → (2 − x)Li(1−x)/(2−x)Ni1/(2−x)O + x/2O2	medical devices, EVs, industrial	Medical devices, industrial, electric powertrain (Tesla)
NMC	Comprised of Nickel cobalt & Manganese	Lithium metal Graphite	Methyl carbonate + Li salt	Polyolefin	Li(x)MO2(s) → Li+(org) + Li(x-1)MO2(s) + e-.	Stationary needing high load currents and endurance	E-bikes, medical devices, EVs, industrial
LFP	Comprised of Lithium, Iron & Phosphate	Graphite Carbon	Propylene carbonate + Li salt	Polyolefin	LiFePO4→FeP04+Li+e	UPS, electric powertrain (Mitsubishi i-MiEV,	Portable and stationary needing high load currents and endurance
LTO	Comprised of Nickel cobalt & Manganese	Lithium–titanium oxide	Propylene carbonate + Li salt	Polyolefin	Li4Ti5O12 + 3Li+ + 3e → 4 Li7Ti5O12	Honda Fit EV), solar-powered street lighting	UPS, electric powertrain (Mitsubishi i-MiEV, Honda Fit EV), solar-powered street lighting

Conclusion :

Hence, we have studied the various types of batteries and their characteristics