Week 1 Understanding Different Battery Chemistry

Q1.) Prepare a table which includes materials & chemical reactions occurring at the anode and cathode of LCO, LMO, NCA, NMC, LFP and LTO-type lithium-ion cells.

Li-ion Batteries

• A lithium-ion battery or Li-ion battery is a type of rechargeable battery. Lithium-ion batteries are commonly used for portable electronics and electric vehicles and are growing in popularity for military and aerospace applications.
• Similar to the lead- and nickel-based architecture, lithium-ion uses a cathode (positive electrode), an anode (negative electrode) and an electrolyte as a conductor.
• The cathode is a metal oxide and the anode consists of porous carbon.
• During discharge, the ions flow from the anode to the cathode through the electrolyte and separator; the charge reverses the direction and the ions flow from the cathode to the anode.
• Figure 1 illustrates the process.

Types of Li-ion Cells

Lithium Cobalt Oxide(LiCoO2) — LCO

• Its high specific energy makes Li-cobalt the popular choice for mobile phones, laptops and digital cameras.
• The battery consists of a cobalt oxide cathode and a graphite carbon anode.
• The cathode has a layered structure and during discharge, lithium ions move from the anode to the cathode.
• The flow reverses on charge.
• The drawback of Li-cobalt is a relatively short life span, low thermal stability and limited load capabilities (specific power).

Lithium Manganese Oxide (LiMn2O4) — LMO

• Li-ion with manganese spinel was first published in the Materials Research Bulletin in 1983. In 1996, Moli Energy commercialized a Li-ion cell with lithium manganese oxide as cathode material.
• The architecture forms a three-dimensional spinel structure that improves ion flow on the electrode, which results in lower internal resistance and improved current handling.
• A further advantage of spinel is high thermal stability and enhanced safety, but the cycle and calendar life is limited.

Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO2) — NCA

• Lithium nickel cobalt aluminium oxide battery, or NCA, has been around since 1999 for special applications.
• It shares similarities with NMC by offering high specific energy, reasonably good specific power and a long life span.
• Less flattering are safety and cost.
• NCA is a further development of lithium nickel oxide; adding aluminium gives the chemistry greater stability.

Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) — NMC

• 
  One of the most successful Li-ion systems is a cathode combination of nickel-manganese-cobalt (NMC).
• Similar to Li-manganese, these systems can be tailored to serve as Energy Cells or Power Cells.
• For example, NMC in a 18650 cell for moderate load conditions has a capacity of about 2,800mAh and can deliver 4A to 5A; NMC in the same cell optimized for specific power has a capacity of only about 2,000mAh but delivers a continuous discharge current of 20A.

Lithium Iron Phosphate(LiFePO4) — LFP

• Li-phosphate offers good electrochemical performance with low resistance.
• This is made possible with nano-scale phosphate cathode material.
• The key benefits are a high current rating and long cycle life, besides good thermal stability, enhanced safety and tolerance if abused.
• Li-phosphate is more tolerant to full charge conditions and is less stressed than other lithium-ion systems if kept at high voltage for a prolonged time.
• As a trade-off, its lower nominal voltage of 3.2V/cell reduces the specific energy below that of cobalt-blended lithium-ion.

Lithium Titanate (Li2TiO3) — LTO

• Batteries with lithium titanate anodes have been known since the 1980s.
• Li-titanate replaces the graphite in the anode of a typical lithium-ion battery and the material forms a spinel structure.
• The cathode can be lithium manganese oxide or NMC.
• Li-titanate has a nominal cell voltage of 2.40V, can be fast charged and delivers a high discharge current of 10C, or 10 times the rated capacity.
• The cycle count is said to be higher than that of a regular Li-ion. Li-titanate is safe, has excellent low-temperature discharge characteristics and obtains a capacity of 80 per cent at –30°C.

Q2.) Compare the differences between each type of Li+ion battery based on their characteristics?

Materials & chemical reactions occur at the anode and cathode of LCO, LMO, NCA, NMC, LFP, and LTO type of lithium-ion cells:

Six types of lithium-ion batteries are compared relative to one another:

Lithium-ion battery Types	SP	SE	SF	LS	CS	PF
Lithium Cobalt Oxide	L	H	L	L	L	M
Lithium Manganese Oxide	M	M	M	L	L	L
Lithium Nickel Manganese Cobalt Oxide	M	H	M	M	L	M
Lithium Iron Phosphate	H	L	H	H	L	M
Lithium Nickel Cobalt Aluminium Oxide	M	H	L	M	M	M
Lithium Titanate	M	L	H	H	H	H

SP stands for specific power

SE stands for specific energy

SF stands for safety

LS stands for lifespan

CS stands for cost

PF stands for performance

L stands for low

M stands for moderate

H stands for high

Summary of the Table

• Lithium Cobalt Oxide has high specific energy as compared to the other batteries which make it the preferred choice for laptops and mobile phones.
• It also has a low cost and a moderate performance.
• However, it is highly unfavourable in all the other aspects when compared to other lithium-ion batteries.
• Has a low specific power, low safety, and a low lifespan.
• Lithium Manganese Oxide has moderate specific power, moderate specific energy, and a moderate level of safety when compared to the other types of lithium-ion batteries.
• It has the added advantage of a low cost.
• The downsides are its low performance and low lifespan.
• It is usually used in medical devices and power tools.
• Lithium Nickel Manganese Cobalt Oxide has two major advantages as compared to the other batteries.
• The first one is its high specific energy, making it desirable in electric powertrains, electric vehicles, and electric bikes.
• The other is its low cost. It is moderate in terms of specific power, safety, lifespan, and performance when compared to other lithium-ion batteries.
• It can be optimized to either have high specific power or high specific energy.
• Lithium Iron Phosphate only has one major disadvantage when compared to other types of lithium-ion batteries and that is its low specific energy.
• Other than that, it has moderate to high ratings in all the other characteristics.
• It has high specific power, offers a high level of safety, has a high lifespan, and comes at a low cost.
• The performance of this battery is also moderate.
• It is often employed in electric motorcycles and other applications that require a long lifespan and a high level of safety.
• Lithium Nickel Cobalt Aluminium Oxide offers one strong advantage compared to the five other batteries: high specific energy.
• It is pretty moderate in the rest of the characteristics like performance, cost, specific power, and lifespan.
• The only downside to this battery type is its low level of safety.
• Its high specific energy and moderate lifespan make it a good candidate for electric powertrains.
• Lithium Titanate offers high safety, high performance, and a high lifespan which are very important features every battery should have.
• Its specific energy is low compared to the five other lithium-ion batteries but it compensates for this with moderate specific power.
• The only major disadvantage of lithium titanate as compared to the other lithium-ion batteries is its extremely high cost.
• Another important feature of this battery worthy of mention is its remarkably fast recharge time.
• It can be used for storing solar energy and creating smart grids.