Week 1 Understanding Different Battery Chemistry

AIM:

1. To prepare repare a table that 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 battery based on their characteristics.

Study 1 :

INTRODUCTION:

• Lithium-ion Cells are a secondary type of battery cell that is they are rechargeable and also they are reusable which makes them ideally suited for automotive applications and certain consumer electronics When two or more cells connected they are referred to as batteries Like other batteries Lithium-ion batteries also rely on the chemical energy stored in the bonds and atoms of elements and compounds and utilize this energy in a chemical reaction occurring inside the cell. The chemical energy from this reaction is converted to electrical energy and it is used. Since the Lithium-ion cells are rechargeable, they can perform the reverse reaction using electricity as well.

CONSTRUCTION:

• Electrolyte :The electrolyte is an ionic conductor that provides the medium for internal ionic charge transfer between the electrodes • The electrolyte must often comprise a liquid solvent containing dissolved chemicals the solution that provides the ionic conductivity

• The Lithium-ion cels use non-aqueous electrolytes.

• Cathode and Anode:The Cathode ad Anoide is the two electrodes that are connected by a wire in an external circuit The electrons are passing through the external wire and so an electric current is perorated.The Anode refers to the Electrode through which the conventional current enters into a polarized electrical device.
• The Cathode refers to the electrode through which conventional current leaves an electrical device.
• Separator:The Separator physically isolates the positive and negative electrodes. The separator is an ionic conductor but an electronic insulator b. It prevents the internal short-circuiting between the two electrodes.
  
• Current Collectors:The current collectors are the electronic conductors with which the electrodes are mixed It does not take part in chemical reactions of the cell but instead, it either allows simple electronic connection to reduce the electronic resistance of an electrode.

Advantages of Lithium-Ion Battery:

1. it has a high energy density which is two times compare to Ni-Cd.The Lithium-Ion battery is rechargeable.
2. There is no memory effect. Hence it is not needed to discharge them completely before recharging.
3. The battery can handle many charge/discharge cycles.
4. The battery can hold the charge and it can lose only 5% of its charge every month.

Disadvantages of Lithium-Ion Battery:

1. It lasts only two to three years after the manufacturer.
   
2. It is sensitive to high temperatures.
3. If the battery is completely discharged, it can no longer be recharged again.
4. It is relatively expensive.
5. if the "separator" gets damaged, it can burst into flames.

Study 2 :

DIFFERENT TYPES OF LITHIUM-ION BATTERIES:

Lithium Cobalt Oxide(LiCo02) - 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 (LiMn204) - 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 (LiNiCOAIO2)-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 (LiNiMnCo02) - 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:

• The figure compares the specific energy of lead-, nickel- and lithium-based systems. While Li-aluminum (NCA) is the clear winner by storing more capacity than other systems, this only applies to specific energy in terms of specific power and thermal stability, Li-manganese (LMO) and Li-phosphate (LFP) are superior, Li-titanate (LTO) may have low capacity but this chemistry outlives most other batteries in terms of de span and also has the best cold temperature performance. Moving towards the electric powertrain safety and the cycle will gain dominance overcapacity (LCO stands for Li-cobalt, the original Li-ion)

CONCLUSION:

• We studied the different batteries by comparing their specific energy,by voltage,power,specific density.

REFERENCES:

• https://batteryuniversity.com/article/understanding-lithium-ion
• https://nickelinstitute.org/blog/2020/february/competitive-technologies-to-high-nickel-lithium-ion-batteries-the-pros-and-cons/