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
LITHIUM-ION BATTERY:
A lithium-ion (Li-ion) battery is an advanced battery technology that uses lithium ions as a key component of its electrochemistry. During a discharge cycle, lithium atoms in the anode are ionized and separated from their electrons. The lithium ions move from the anode and pass through the electrolyte until they reach the cathode, where they recombine with their electrons and electrically neutralize. The lithium ions are small enough to be able to move through a micro-permeable separator between the anode and cathode. In part because of lithium's small size (third only to hydrogen and helium), Li-ion batteries are capable of having a very high voltage and charge storage per unit mass and unit volume.
Li-ion batteries can use a number of different materials as electrodes. The most common combination is that of lithium cobalt oxide (cathode) and graphite (anode), which is most commonly found in portable electronic devices such as cellphones and laptops. Other cathode materials include lithium manganese oxide (used in hybrid electric and electric automobiles) and lithium iron phosphate. Li-ion batteries typically use ether (a class of organic compounds) as an electrolyte.
TYPES OF LITHIUM ION BATTERY :
1. Lithium Cobalt Oxide ( LiCo02 ) - LCO
2. Lithium Manganese Oxide ( LiMn204 ) - LMO
3. Lithium Nickel Manganese Cobalt Oxide ( LiNiMnGp02 ) - NMC
4. Lithium Iron Phosphate ( LiFePO4 ) - LFP
5. Lithium Nickel Cobalt Aluminum Oxide ( LiNiCoAlO2 ) - NCA
6. Lithium Titanate ( Li2TiO3 ) - LTO
Lithium Cobalt Oxide (LiCoO2) - LCO
Its High Specific Energy Making Li - cobalt The popular choice for mobile phones, laptops, and digital cameras. The battery charge of a cobalt oxide cathode and a graphite carbon anode. The cathode has a layered structure and during discharge, the lithium ions move from the anode to the cathode. A charge on the flow reverses. 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 a cathode material. The architecture forms a three-dimensional spinel structure that results in an ion flow that 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 Manganese Cobalt Oxide ( LiNiMnCoO₂ ) - NMC
One of the most successful Li - ion systems is a cathode combination of 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 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. A silicon based anode will go to 4,000mAh and higher but at reduced loading capability and shorter cycle life. Silicon added to graphite has the drawback that the anode grows and shrinks with charge and discharge, making the cell mechanically unstable .
Lithium Iron Phosphate ( LiFePO4 ) - LFP
In 1996 , the University of Texas ( and other contributors ) discovered phosphate as cathode material for rechargeable lithium batteries. 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.
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. Figure 11 summarizes the six key characteristics . NCA is a further development of lithium nickel oxide ; adding aluminum gives the chemistry greater stability.
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 ( -22 ° F ).
Table:
2.Compare the differences between each type of Li+ion batteries based on their characteristics
The Major 6 types of lithium ion batteries was discussed early.Now the major differences in the characteristics can be found when choosing a battery . 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 , the higher the cycles can takes 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.
Specific energy of different types of lithium based batteries :
The main differences between the lithium ion batteries can be differentiated on the characteristics.
• Nominal Voltage : Most of the batteries are very close when it comes to characteristics . LMO ( 3.7 ) has the highest range and LTO ( 2.4 ) has the lowest range in volts.
• Cycle life : They differ by a significant amount from each other. LTO battery has the longest life cycle so that it can last longer period of time and it is exactly opposite for the LMO type batteries.
• Charge current rate : Higher the charge current , the less time the battery will take to get fully charged. LTO and LTP are highest NCA comes close to its condenders.
• Discharge current rate : If we need higher discharge rates and faster charging times we should choose a high rated battery instead . LTO has a discharge rate 10 times higher than the others and it t - is one of the safest batteries.
• Thermal runaway : A thermal tunaway occurs in situations where an increase in temperature changes the conditions in a way that causes increase in temperature often leading a destructive result . LTO has the highest temperature rating in this and NCA and LCP has its lowest.
● Specific energy : The specific energy density can be calculated by integrating from 0 to t_cutoff. We can obtain the specific energy density in Wh Kg ^ -1. Lithium ion with cobalt cathodes offer the highest energy densities. This types of applications are cell phones , laptops and digital cameras Power density indicates how much power a battery can deliver on demand.
For ease of choosing a battery from laymans perspective , the 6 key features are given a value within 0-5 range for all of the are given with the same parameters which are considered in case of 5 point hexagonal analysis of the batteries. They are
1. Specific energy.
2. Specific power.
3. Safety.
4. Performance.
5. Life span.
6. Cost.
LCO:
Li - cobalt excels on high specific energy but offers only moderate performance specific power, safety and life span.
LMO:
Although moderate in overall performance , newer designs of Li - manganese offer improvements in specific power , safety and life span.
NMC:
NMC has good overall performance and excels on specific energy . This battery is the preferred candidate for the electric vehicle and has the lowest self heating rate.
LFP:
Li - phosphate has excellent safety and long life span but moderate specific energy and elevated self discharge.
NCA:
High energy and power densities as well as a good life span make NCA a candidate for EV powertrains. High cost and marginal safety are negative.
LTO:
Li - titanate excels in safety , low temperature performance and life span . Efforts are being made to improve the specific energy and lower the cost.
• These types of lithium ion batteries are some of the most popular. As technology is continously seeing more development, new lithium technologies are always being developed and those which exists are being developed.