Week 1 Understanding Different Battery Chemistry
Aim:-
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
Study 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.
What is a Battery?
- A battery can be defined as an electrochemical device (consisting of one or more electrochemical cells) which can be charged with an electric current and discharged whenever it is required.
- A battery is a a device that stores chemical energy and converts into electrical energy.
- Batteries are made up of three basic components:They are positive terminal is Cathode and negative terminal is Anode and some kind of electrolyte.
They are two types of batteries.They are
- Primary Cell:-Batteries that must be used for one time use and they cannot be recharged
- Secondary Cell :- Batteries that can be recharged and can be used for multiple times.
Battery Components:-
Batteries are made up of three basic components: an anode, a cathode, and an electrolyte.
The Anode is the negative or reducing electrode that releases electrons to the external circuit and oxidizes during and electrochemical reaction.
The Cathode is the positive or oxidizing electrode that acquires electrons from the external circuit and is reduced during the electrochemical reaction.
The Electrolyte is the medium that provides the ion transport mechanism between the cathode and anode of a cell. Electrolytes are often thought of as liquids, such as water or other solvents, with dissolved salts, acids, or alkalis that are required for ionic conduction. It should however be noted that many batteries including the conventional (AA/AAA/D) batteries contain solid electrolytes that act as ionic conductors at room temperature.
How does Li-ion Batter works?
A battery is made up of an anode, cathode, separator, electrolyte, and two current collectors (positive and negative). The anode and cathode store the lithium. The electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa through the separator. The movement of the lithium ions creates free electrons in the anode which creates a charge at the positive current collector. The electrical current then flows from the current collector through a device being powered (cell phone, computer, etc.) to the negative current collector. The separator blocks the flow of electrons inside the battery.
CHARGE/DISCHARGE
While the battery is discharging and providing an electric current, the anode releases lithium ions to the cathode, generating a flow of electrons from one side to the other. When plugging in the device, the opposite happens: Lithium ions are released by the cathode and received by the anode.
Types of Li-ion Batteries:-
- Lithium Cobalt Oxide(LiCoO2) — LCO
- Lithium Manganese Oxide (LiMn2O4) — LMO
- Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) — NMC
- Lithium Iron Phosphate(LiFePO4) — LFP
- Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2) — NCA
- Lithium Titanate (Li2TiO3) — LTO
Comparision table:-
Reference:-https://batteryuniversity.com/learn/article/types_of_lithium_ion
Google drive link:-https://docs.google.com/spreadsheets/d/14-NbM5i7FS9hTqn0a18WOOGUUmsmMlGu_y_q7_BQQJA/edit#gid=0
|
Sl.no |
Li - ion Battery Type |
Cathode |
Anode |
Advantages |
Drawbacks |
Applications |
Structure |
|
1 |
(LiCoO2) — LCO |
Li Cobalt oxide |
Graphite carbon |
high specific energy |
short life span, low thermal stability and limited load capabilities (specific power), Cobalt is expensive |
mobile phones, laptops and digital cameras |
 |
|
2 |
(LiMn2O4) — LMO |
lithium manganese oxide |
Graphite carbon |
lower internal resistance and improved current handling, high thermal stability and enhanced safety |
cycle and calendar life are limited |
Electric vehicles such as the Nissan Leaf, Chevy Volt and BMW i3, Power tools, medical devices, electric powertrains |
 |
|
3 |
(LiNiMnCoO2) — NMC |
Lithium Nickel Manganese Cobalt Oxide |
Graphite carbon |
good overall performance and excels on specific energy, lowest self-heating rate |
high cost due to cobalt |
E-bikes, medical devices, EVs, industrial |
 |
|
4 |
(LiFePO4) — LFP |
Lithium Iron Phosphate |
Graphite carbon |
high current rating and long cycle life, besides good thermal stability, enhanced safety and tolerance if abused. |
higher self-discharge, less specific energy |
Portable and stationary needing high load currents and endurance |
 |
|
5 |
(LiNiCoAlO2) — NCA |
Lithium Nickel Cobalt Aluminum Oxide |
Graphite carbon |
high specific energy, reasonably good specific power, long life span |
High cost and marginal safety |
Medical devices, industrial, electric powertrain (Tesla) |
 |
|
6 |
(Li2TiO3) — LTO |
lithium manganese oxide or NMC |
Li2TiO3 (titanate) |
Fast charging, safe, high discharge current of 10C |
Low specific energy |
UPS, electric powertrain (Mitsubishi i-MiEV, Honda Fit EV), solar-powered street lighting |
 |
Study 2:-Compare the differences between each type of Li+ion batteries based on their characteristics
Li+ion batteries:-
- Lithium Cobalt Oxide(LiCoO2) — LCO
- Lithium Manganese Oxide (LiMn2O4) — LMO
- Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) — NMC
- Lithium Iron Phosphate(LiFePO4) — LFP
- Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2) — NCA
- Lithium Titanate (Li2TiO3) — LTO
1. 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.
- Li-cobalt should not be charged and discharged at a current higher than its C-rating. This means that an 18650 cell with 2,400mAh can only be charged and discharged at 2,400mA.
- The Li-cobalt is losing favor to Li-manganese, but especially NMC and NCA because of the high cost of cobalt and improved performance by blending with other active cathode materials.
2.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.
- Low internal cell resistance enables fast charging and high-current discharging.
- In an 18650 package, Li-manganese can be discharged at currents of 20–30A with moderate heat buildup.
- It is also possible to apply one-second load pulses of up to 50A. A continuous high load at this current would cause heat buildup and the cell temperature cannot exceed 80°C (176°F). Li-manganese is used for power tools, medical instruments, as well as hybrid and electric vehicles.
- Li-manganese has a capacity that is roughly one-third lower than Li-cobalt. Design flexibility allows engineers to maximize the battery for either optimal longevity (life span), maximum load current (specific power) or high capacity (specific energy).
3. Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) — NMC
The secret of NMC lies in combining nickel and manganese. An analogy of this is table salt in which the main ingredients, sodium and chloride, are toxic on their own but mixing them serves as seasoning salt and food preserver. Nickel is known for its high specific energy but poor stability; manganese has the benefit of forming a spinel structure to achieve low internal resistance but offers a low specific energy. Combining the metals enhances each other strengths.
- NMC is the battery of choice for power tools, e-bikes and other electric powertrains.
- The cathode combination is typically one-third nickel, one-third manganese and one-third cobalt, also known as 1-1-1. Cobalt is expensive and in limited supply.
- Battery manufacturers are reducing the cobalt content with some compromise in performance. A successful combination is NCM532 with 5 parts nickel, 3 parts cobalt and 2 parts manganese. Other combinations are NMC622 and NMC811.
- Cobalt stabilizes nickel, a high energy active material
- New electrolytes and additives enable charging to 4.4V/cell and higher to boost capacity. Figure 7 demonstrates the characteristics of the NMC.
4. Lithium Iron Phosphate(LiFePO4) — LFP
- 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.
- Li-phosphate has a higher self-discharge than other Li-ion batteries, which can cause balancing issues with aging. This can be mitigated by buying high quality cells and/or using sophisticated control electronics, both of which increase the cost of the pack. Cleanliness in manufacturing is of importance for longevity. There is no tolerance for moisture, lest the battery will only deliver 50 cycles.
- Li-phosphate is often used to replace the lead acid starter battery. Four cells in series produce 12.80V, a similar voltage to six 2V lead acid cells in series.
- Vehicles charge lead acid to 14.40V (2.40V/cell) and maintain a topping charge.
- Topping charge is applied to maintain full charge level and prevent sulfation on lead acid batteries.
- With four Li-phosphate cells in series, each cell tops at 3.60V, which is the correct full-charge voltage.
- Cold temperature also reduces performance of Li-ion and this could affect the cranking ability in extreme cases.
5. 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.
6. Lithium Titanate (Li2TiO3) — LTO
- 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).
- LTO (commonly Li4Ti5O12) has advantages over the conventional cobalt-blended Li-ion with graphite anode by attaining zero-strain property, no SEI film formation and no lithium plating when fast charging and charging at low temperature. Thermal stability under high temperature is also better than other Li-ion systems; however, the battery is expensive. At only 65Wh/kg, the specific energy is low, rivalling that of NiCd. Li-titanate charges to 2.80V/cell, and the end of discharge is 1.80V/cell. Figure 13 illustrates the characteristics of the Li-titanate battery.
- Typical uses are electric powertrains, UPS and solar-powered street lighting.