Week 1 Understanding Different Battery Chemistry

Types of Li-ion Battery

Li-ion batteries can be classified based on the combination of anode and cathodes used. There are six categories of lithium-ion battery readily available in the market, these are Lithium Cobalt Oxide (LCO), Lithium Manganese Oxide (LMO), Lithium Nickel Manganese Cobalt Oxide (NMO), Lithium Iron Phosphate (LFP), Lithium Nickel Cobalt Aluminum Oxide (NCA), and Lithium Titanate (LTO). Apart from the LTO battery, all other Li-ion battery has graphite as an anode. All the above Li-ion chemistries have different properties and we need to know their properties, their operating conditions and other parameters in order to select the best battery for our application. The properties of all the chemistries are given below.

1. LITHIUM COBALT OXIDE (LCO): Energy Dense but Low Thermal Stability

Lithium cobalt oxide battery have cobalt as the main active material in its cathode. It was invented in 1991 and has been extensively used because of its high energy density of 150-200 Wh/kg. Although this battery chemistry is energy dense, but other options are being investigated as the experts are claiming that the world could face a cobalt supply shortage soon. This is due to the surge in sales of electric vehicles where this battery chemistry is extensively used, leading to increase in cost over time.

Cobalt is a highly volatile metal, which limits the current handling capabilities of LCO battery due the risk of overheating. Furthermore, LCO batteries have lower thermal stability, that makes them sensitive to higher operating temperatures and overcharging.

LCO batteries are extensively used in portable electronics such as phones, cameras, laptops and have a high demand in electric vehicles. 

2. LITHIUM MANGANESE OXIDE (LMO): The Safest Li-ion Chemistry

Lithium manganese oxide batteries are also known as lithium-ion manganese batteries. It has LiMn2O4 as a cathode. The earliest commercially developed battery with this chemistry was produced in 1996. These batteries have low internal resistance and high temperature stability which makes them safer than other lithium-ion battery types. LMO batteries are capable of delivering current up to 20-30 Amps due to their low internal resistance, thus making fast charging and discharging possible.  

The main disadvantage of this chemistry is its relatively low cycle life of 300-700 cycles. These batteries also have lower capacity. Because of these drawbacks limited research and advancement of this battery type are expected in the future.

LMO batteries are extensively used in applications where high C-rates are required such as power tools. It also has applications in EVs and in medical applications.

3. LITHIUM IRON PHOSPHATE (LFP): Affordable, Safe, and Reliable

Lithium iron phosphate batteries use phosphate as active material in the cathode. These batteries are one of the most used chemistries in electric motorcycles, e-rikshaw as well as other applications that need a long lifecycle and significant safety. These batteries have a moderately high energy density of 90-160 Wh/kg. Similar to LMO, LFP chemistry have low internal resistance resulting in higher thermal stability. Unlike the LCO battery, these batteries are durable and have a long lifecycle with low self-discharge rates. LFP batteries have one of the best life cycles making them a very cost-effective option considering their long operations life. However, the nominal voltage of 3.2V of the li-phosphate battery means that it has less energy than other types of lithium batteries. 

LFP batteries are used in industrial equipment and heavy machinery due to their high thermal stability and great life cycles. They are widely used in EVs, especially in e-bikes, e-rikshaw, and many cars because of their ability to withstand a lot of mechanical and thermal abuse. 

4. LITHIUM NICKEL MANGANESE COBALT OXIDE (NMC): Expensive but High Performing Battery

Lithium Nickel Manganese Cobalt Oxide (NMC) Batteries uses a combination of nickel, manganese and cobalt as the active material for its cathode. The most commonly used ratio is 60 percent nickel mixed with 20 percent each of manganese and cobalt to form the alloy. Changing the ratio of these metals can alter the property and we can either attain a high specific energy density or a high specific power. These batteries are cheaper than other Li-ion batteries and have a very low self-heating rate and a nominal voltage of 3.7V. NMC batteries have energy density of 150-220 Wh/kg, which is higher than most other chemistries. 

This battery is commonly used to power medical equipment, power tools and is considered as one of the preferred battery chemistries for EVs.

5. LITHIUM NICKEL COBALT ALUMINUM OXIDE (LINICOALO2) NCA: High Energy with Long Life

Lithium Nickle Cobalt batteries, also known as NCA batteries have a combination of nickel, cobalt and aluminum as active material in its cathode. These batteries have a high life cycle and are one of the most energy-dense Li-ion chemistry with energy density as high as 260Wh/kg and a nominal voltage of 3.6V. But the main disadvantage of this battery is its lower thermal stability and high cost making them an unviable option for consumer electronics. They are a good option for EVs due to their energy density, the NCA batteries must be used in cars with extra safety measures to monitor their performance and other data to keep the drivers secure.

The NCA batteries are becoming increasingly important in electric powertrains such as in Tesla and find application in grid storage due to their lifespan and energy density. 

6. Lithium titanate LTO: Long life, fast charge using advanced Nanotechnology

Lithium titanate, also known as li-titanate are one of the newly developed Li-ion chemistries. They have advanced nanotechnology and replace the graphite used in the anode with lithium titanate as the active material. The large surface area of Li-titanate allows a larger quantity of electrons to enter and exit the anode faster, making a very high rate of charging and discharging possible without compromising on safety. The main drawback of this battery is that it suffers from is the low nominal voltage and low energy density of 2.4V and 50-80Wh/kg respectively. What makes this battery special is its ability to provide discharge rate exceeding 30 C for a short period of time. The use of advance nanotechnology makes it one of the safest chemistries available in today’s time. 

Currently, a lot of big manufacturers of electric vehicles and bikes such as Mitsubishi, Honda, etc., use li-titanate batteries, and there is potential for this type of battery to be used in electric buses for public transportation. 

LTO batteries have potential scope in aerospace, military and are used in battery energy storage systems for storing wind energy and solar energy and for creating smart grids. Their ability to sustain high discharge rates make them a preferred option for frequency control devices for grid applications. 

Reaction of lithium ion battery:-

for choosing a battery from laymans perspective the 6 key feactures are given value with 0-5 for all of the given parameter which are considered in case of 5 point hexagonal analysis of the battery such as.

1.Specific energy

2.Specific Power

3.Safety

4.Performance

5.Life span

6.Cost

There are attached image for more clerification:-