Week 1 Understanding Different Battery Chemistry

Aim -

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.

Theory -

Battery -

• A Battery is a device equipped with one or more electrochemical cells with external connections for powering electrical devices such as Flashlights, mobile phones and electric cars.
• 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.

Types of Batteries -

• Primary cell - These batteries are one time use batteries and they cannot be recharged for further usage.
• Secondary cell - These batteries can be recharged and can be used for multiple times.

PARTS OF LITHIUM ION BATTERY -

Li-ion batteries consist of largely four main components : cathode, anode, electrolyte, lithium ion and separator.

Working of Li-ion battery -

While the battery is in discharging state, providing an electric current, the anode releases lithium ions to the cathode, generating a flow of electrons from one side to the other. When plugging in the device the opposite flow will happen i.e., lithium ions are released by the cathode and received by the anode.

The 6 commonly used Lithium-ion batteries are listed below.

• Lithium Cobalt Oxide (LiCoO2) - LCO.
• Lithium Manganese Oxide (LiMn2O4) - LMO.
• Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO2) - NCA.
• Lithium Nickel Manganese Cobalt Oxide (liNiMnCoO2) - NMC.
• Lithium Iron Phosphate (LiFePO4) - LFP.
• Lithium Titanate (Li2TiO3) - LTO.

Explaination -

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.

2. Lithium Manganese Oxide (LiMn2O4) - LMO.

• Lithium manganese oxide batteries are notable for their high temperature stability and are also safer than other lithium-ion battery types, this is the reason why they are often used in medical equipment and devices, but they may also be used in power tools, electric bikes and more.

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 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 too.

4. Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) - 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. However 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 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-po 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.
• Accordingly, these batteries are often used in electric motorcycles as well as other applications that need a long lifecycle and significant safety.

6. Lithium Titanate (Li2TiO3) - LTO.

• Lithium 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

Difference between each type of Li-ion Battries -

The major things that can be differenciated from one another -

• Nominal voltage - It is the system voltage at which the device is designed to operate. The rated voltage is usually higher than the nominal voltage to ensure the safe operation of the device.
• Cycle - The charge and discharge when took place for a single time makes a cycle. The higher the cycles can take place, then the lifespan is higher.
• Thermal runway - The thermal runway begins when the heat generated within a battery exceeds the amount of heat that is dissipated to its surroundings. Internal battery temperature will continue to rise, causing the battery current to rise creating a domino effect. The rise in temperature in a single battery will begin to affect other batteries nearby and the pattern will continue.
• Specific energy - It is the amount of energy stored per unit mass (Wh/Kg). This is a very important deciding factor that decides how much energy or power from different batteries with the same amount of weight.

Comparision -

1. Lithium Cobalt Oxide (LiCoO2) - LCO.

• This battery has the highest energy density. The specific energy is in the range of 150 to 200 Wh/Kg.
• It has a short life span due to formation of solid Electrolyte Layer (SEI) at anode and lithium plating due to fast charging and charging at low temperature.
• Typically it has life span of 500 to 1000 cycles.
• The thermal runaway occurs at 150 degree C.

2. Lithium Manganese Oxide (LiMn2O4) - LMO.

• It has shorter lifetime of 300-700 cycles and lower capacity The specific energy of this battery is 100-150 Wh/kg.

• The spinel structure (AB2O4 Structure) of Lithium manganese enables this type of battery to have better thermal stability so it is better in terms of safety.

• The thermal runaway at a high temp of 250 C.

3. Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO2) - NCA.

• It has feature similar to NMC Battery high specific energy (200-260 Wh/kg) Good specific power and a long life span.

• It is a further development of lithium Nickel oxide Adding Aluminium to the chemistry gives the battery greater stability.

4. Lithium Nickel Manganese Cobalt Oxide (liNiMnCoO2) - NMC.

• This combination has a mixture of one third nickel, one third Cobalt, and one third Manganese, Cobalt is expensive and limited in supply.

• Thermal runaway occurs at a high temp of 210 C.

• It has a life span of 1000 to 2000 cycles.

5. Lithium Iron Phosphate (LiFePO4) - LFP.

• It can be used for higher number of discharge cycles as high as 2000.

• This battery has good thermal stability Thermal runaway is caused at 270 C.

• Due to the presence of phosphate (PO4) that can cope up with high temp At cathode Phosphate anions are bonded with iron cations.

6. Lithium Titanate (Li2TiO3) - LTO.

• This battery is safe it has good low temp. discharge capability and can achieve C charger level of 80% atv -30 c.

• It has a greater life span than any other Lithium-ion battery It can go up to 5000 Cycles.

• In this battery Graphite as anode is replaced by Lithium Titanate formed into a spinel structure. It has fast charge capability and a high discharge current of 10c which is 10 times the usual capacity.