Week 1 Understanding Different Battery Chemistry
Week 1 Understanding Different Battery Chemistry
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
SOLUTION : -
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 electrolyte as 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; 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 are limited.
Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2) — NCA : -
Lithium nickel cobalt aluminum 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 aluminum 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 an 18650 cell for moderate load condition 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 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 into 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 percent at –30°C.
The materials & chemical reactions occurring at the anode, cathode and overall reactions of all the types of Li-ion cells are given in the table below :
An excel sheet with the above table is attached on submission.
SOLUTION : - 2
2.Compare the differences between each type of Li+ion batteries based on their characteristics
A Simple Comparison of Six Lithium-ion Battery Types : -
Lithium-ion batteries are on the rise in electromobility.
What Are Lithium Batteries ?
Lithium-ion batteries are used in most aspects of our everyday lives. Most devices like smartphones and laptops cannot operate without these batteries. Lithium-ion batteries have also become very important in the field of electromobility as it is now the battery of choice in most electric vehicles. Its high specific energy gives it an advantage over other batteries.
There are different types of lithium-ion batteries and the main difference between them lies in their cathode materials. Different kinds of lithium-ion batteries offer different features, with trade-offs between specific power, specific energy, safety, lifespan, cost, and performance.
The six lithium-ion battery types that we will be comparing are Lithium Cobalt Oxide, Lithium Manganese Oxide, Lithium Nickel Manganese Cobalt Oxide, Lithium Iron Phosphate, Lithium Nickel Cobalt Aluminum Oxide, and Lithium Titanate. Firstly, understanding the key terms below will allow for a simpler and easier comparison.
Battery Terms
Specific energy:
This defines the battery capacity in weight (Wh/kg). The capacity relates to the runtime. Products requiring long runtimes at moderate load are optimized for high specific energy.
Specific power:
It's the ability to deliver a high current and indicates loading capability. Batteries for power tools are made for high specific power and come with a reduced specific energy.
A high specific power usually comes with reduced specific energy and vice versa. The pouring of bottled water into a glass is a perfect analogy of the relationship between specific power and specific energy. The water in the bottle can be thought of as specific energy. Pouring the water at a slow rate doesn’t provide enough force (low specific power), but the water lasts longer in the bottle (high specific energy). On the other hand, if we pour the water out at a faster rate, it provides a greater impact (high specific power). However, the water wouldn’t last very long in the bottle ( low specific energy).
The pouring of bottled water in a glass is a perfect analogy of the relationship between specific power and specific energy.
Performance:
This measures how well the battery works over a wide range of temperatures. Most batteries are sensitive to heat and cold and require climate control. Heat reduces life, and cold lowers performance temporarily.
Lifespan:
This reflects cycle life and longevity and is related to factors such as temperature, depth of discharge, and load. Hot climates accelerate capacity loss. Cobalt blended lithium-ion batteries also usually have a graphite anode that limits the cycle life.
Safety:
This relates to factors such as the thermal stability of the materials used in the batteries. The materials should have the ability to sustain high temperatures before becoming unstable. Instability can lead to thermal runaway in which flaming gases are vented. Fully charging the battery and keeping it beyond the designated age reduces safety.
Cost:
Demand for electric vehicles has generally been lower than anticipated, mainly due to the cost of lithium-ion batteries. Hence cost is a huge factor when selecting the type of lithium-ion battery.
Types of Lithium Batteries :
Now that we understand the major battery characteristics, we will use them as the basis for comparing our six types of lithium-ion batteries. The characteristics are rated as either high, moderate, or low. The table below provides a simple comparison of the six lithium-ion battery types.
It is important to note that the 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 Aluminum 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 compared to the other batteries, making it the preferred choice for laptops and mobile phones. It also has a low cost and a moderate performance. However, it is highly unfavorable in all the other aspects when compared to the other lithium-ion batteries. It has 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, which makes 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 the 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 Aluminum 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.
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