Week 1 Understanding Different Battery Chemistry
AIM:
1.To 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.To Compare the differences between each type of Li+ion batteries based on their characteristics
THEORY:
Like any other battery, a rechargeable lithium-ion battery is made of one or more power-generating compartments called cells. Each cell has essentially three components: a positive electrode (connected to the battery's positive or + terminal), a negative electrode (connected to the negative or − terminal), and a chemical called an electrolyte in between them. The positive electrode is typically made from a chemical compound called lithium-cobalt oxide (LiCoO2) or, in newer batteries, from lithium iron phosphate (LiFePO4). The negative electrode is generally made from carbon (graphite) and the electrolyte varies from one type of battery to another
When the battery is charging up, the lithium-cobalt oxide, positive electrode gives up some of its lithium ions, which move through the electrolyte to the negative, graphite electrode and remain there. The battery takes in and stores energy during this process. When the battery is discharging, the lithium ions move back across the electrolyte to the positive electrode, producing the energy that powers the battery. In both cases, electrons flow in the opposite direction to the ions around the outer circuit. Electrons do not flow through the electrolyte: it's effectively an insulating barrier, so far as electrons are concerned.
The movement of ions (through the electrolyte) and electrons (around the external circuit, in the opposite direction) are interconnected processes, and if either stops so does the other. If ions stop moving through the electrolyte because the battery completely discharges, electrons can't move through the outer circuit either—so you lose your power. Similarly, if you switch off whatever the battery is powering, the flow of electrons stops and so does the flow of ions. The battery essentially stops discharging at a high rate (but it does keep on discharging, at a very slow rate, even with the appliance disconnected).
Unlike simpler batteries, lithium-ion ones have built in electronic controllers that regulate how they charge and discharge. They prevent the overcharging and overheating that can cause lithium-ion batteries to explode in some circumstances.
lithium-ion batteries are all about the movement of lithium ions: the ions move one way when the battery charges (when it's absorbing power); they move the opposite way when the battery discharges (when it's supplying power):
During charging, lithium ions (yellow circles) flow from the positive electrode (red) to the negative electrode (blue) through the electrolyte (gray). Electrons also flow from the positive electrode to the negative electrode, but take the longer path around the outer circuit. The electrons and ions combine at the negative electrode and deposit lithium there.
When no more ions will flow, the battery is fully charged and ready to use.
During discharging, the ions flow back through the electrolyte from the negative electrode to the positive electrode. Electrons flow from the negative electrode to the positive electrode through the outer circuit, powering your laptop. When the ions and electrons combine at the positive electrode, lithium is deposited there.
When all the ions have moved back, the battery is fully discharged and needs charging up again.
The li-ion battery advantages include:
- High energy density: The high energy density is one of the chief advantages of lithium ion battery technology. With electronic equipment such as mobile phones needing to operate longer between charges while still consuming more power, there is always a need to batteries with a much higher energy density. In addition to this, there are many power applications from power tools to electric vehicles. The much higher power density offered by lithium ion batteries is a distinct advantage. Electric vehicles also need a battery technology that has a high energy density.
- Self-discharge: One issue with many rechargeable batteries is the self discharge rate. Lithium ion cells is that their rate of self-discharge is much lower than that of other rechargeable cells such as Ni-Cad and NiMH forms. It is typically around 5% in the first 4 hours after being charged but then falls to a figure of around 1 or 2% per month.
- Low maintenance: One major lithium ion battery advantage is that they do not require and maintenance to ensure their performance.
Fortunately one of the advantages of lithium ion batteries is that there is no active maintenance required. - Cell voltage: The voltage produced by each lithium ion cell is about 3.6 volts. This has many advantages. Being higher than that of the standard nickel cadmium, nickel metal hydride and even standard alkaline cells at around 1.5 volts and lead acid at around 2 volts per cell, the voltage of each lithium ion cell is higher, requiring less cells in many battery applications. For smartphones a single cell is all that is needed and this simplifies the power management.
- Load characteristics: The load characteristics of a lithium ion cell or battery are reasonably good. They provide a reasonably constant 3.6 volts per cell before falling off as the last charge is used.
- No requirement for priming: Some rechargeable cells need to be primed when they receive their first charge. One advantage of lithium ion batteries is that there is no requirement for this they are supplied operational and ready to go.
- Variety of types available: There are several types of lithium ion cell available. This advantage of lithium ion batteries can mean that the right technology can be used for the particular application needed. Some forms of lithium ion battery provide a high current density and are ideal for consumer mobile electronic equipment. Others are able to provide much higher current levels and are ideal for power tools and electric vehicles.
The li-ion battery disadvantages include:
- Protection required: Lithium ion cells and batteries are not as robust as some other rechargeable technologies. They require protection from being over charged and discharged
- Ageing: One of the major lithium ion battery disadvantages for consumer electronics is that lithium ion batteries suffer from ageing.
- Transportation: This li-ion battery disadvantage has come to the fore in recent years. Many airlines limit the number of lithium ion batteries they take, and this means their transportation is limited to ships.
- Cost: A major lithium ion battery disadvantage is their cost. Typically they are around 40% more costly to manufacture than Nickel cadmium cells.
- Developing technology: Although lithium ion batteries have been available for many years, it can still be considered an immature technology by some as it is very much a developing area.
TABLE:
| LI ION BATTERIES TYPES | LCO | LMO | NCA | NMC | LFP | LTO |
| Abbreviation | LiCoO2 (LCO) |
LiMn2O4 (LMO) |
LiNiCoAlO2 | LiNiMnCoO2 | LiFePO4 | Li2TiO3 |
| ANODE MATERIAL | graphite | graphite | graphite | graphite | graphite | lithium titanate |
| CATHOD MATERIAL | LiCoO2 | LiMn2O4 | LiNiCoAlO2 | LiNiMnCoO2 | LiFePO4 | lithium manganese oxide |
| ANODE REACTION | LiC6→xLi++xe-+C6 | LiC6→xLi++xe-+C6 | LiC6→xLi++xe-+C6 | LiC6→xLi++xe-+C6 | LiC6→xLi++e−+C6 | Li4Ti5O12→Ti5012+4Li++4e- |
| CATHOD REACTION | Li1−xCoO2+xLi++xe−→LiCoO2 | 4Li1-xMn204+xLi++xe-→LiMn2O4 | Li1-xNiCoAlO2+xLI++xe-→LiC6+NiCoAlO2 | Li1-xNi0.8Mn0.1Co0.1O2+xLi++xe-→LiNi0.8Mn0.1Co0.1O2 |
LiFe(III)PO4+xLi++xe−→LiFe(II)PO4 FePO4+Li++e−→LiFePO |
4Li1-xMn204+4Li++4e-→4LiMnO2O4 |
| OVERALL REACTION | C6+LiCoO2⟷LixC6+Li1−xCoO2 | C6+LiMn2O4→LiC6+Mn2O4 | C6+LiNiCoAlO2→LiC6+NiCoAlO2 | C6+LiNi0.8Mn0.1Co0.1O2→LiC66+Ni0.8Mn0.Co0.1O2 | LiFePO4+6C→LiC6+FePO4 | Li4Ti5O12+4Mn204→4LiMn2O4+Ti5O12 |
| ELECTROLYTE | ethylene carbonate | lithium halide | ethylene carbonate | lithium salt | ethylene carbonate | lithium salt |
| SEPERATOR | polyolefin | polyolefin | polyolefin | polyolefin | polyolefin | polyolefin |
| Nominal voltage | 3.6V | 3.7V | 3.6V | 3.63V | 3.2V 3.3V | 2.4V |
| FULL CHARGE | 4.2V | 4.2V | 4.2V | 4.2V | 3.65V | 2.85V |
| FULL DISCHARGE | 3V | 3V | 3V | 3V | 2.5V | 1.8V |
| SPECIFIC ENERGY | 150-200WH/Kg | 100-150WH/Kg | 200-260WH/Kg | 150-220WH/Kg | 90-120WH/Kg | 70-80WH/Kg |
| THERMAL RUNAWAY | 150°C (302°F). Full charge promotes thermal runaway | 250°C (482°F) typical. High charge promotes thermal runaway | 150°C (302°F) typical, High charge promotes thermal runaway | 210°C (410°F) typical. High charge promotes thermal runaway | 270°C (518°F) Very safe battery even if fully charged | One of safest Li-ion batteries |
| Charge rate | 0.7–1C (3h) | 0.7–1C (3h) | 1C | 0.7–1C (3h) | 1C (3h) | 1C (5C max) |
| Discharge rate | 1C (1h) | 1C, 10C possible | 1C | 1–2C | 1C (25C pule) | 10C possible |
| Cycle life (ideal) | 500–1000 | 300–700 | 500 | 1000–2000 | 1000–2000 | 3,000–7,000 |
| Packaging (typical) | 18650, prismatic and pouch cell | prismatic | 18650 | 18650, prismatic and pouch cell | 26650, prismatic | prismatic |
| History | 1991 (Sony) | 1996 | 1999 | 2008 | 1996 | 2008 |
| Applications | Mobile phones, tablets, laptops, cameras | Power tools, medical devices, powertrains | Medical, industrial, EV (Tesla) |
E-bikes, medical devices, EVs, industrial | Stationary with high currents and endurance | UPS, EV, solar street lighting |
| Comments | High energy, limited power. Market share has stabilized. | High power, less capacity; safer than Li-cobalt; often mixed with NMC to improve performance. | Highest capacity with moderate power. Similar to Li-cobalt. | High capacity and high power. Market share is increasing. Also NCM, CMN, MNC, MCN | Flat discharge voltage, high power low capacity, very safe; elevated self-discharge. | Long life, fast charge, wide temperature range and safe. Low capacity, expensive. |
DIFFERENT TYPES OF LITHIUM ION BATTERIES:
LITHIUM COBALT OXIDE (LCO)
Also known as lithium cobaltate or lithium-ion cobalt batteries, lithium cobalt oxide batteries are made from lithium carbonate and cobalt. Due to their very high specific energy, these batteries are used for cell phones, laptops and electronic cameras. They have a cobalt oxide cathode and use graphite carbon as their anode material; during discharge, lithium ions move from anode to cathode, with the flow reversing when the battery is charging.
This type of battery has some drawbacks, including a relatively short battery life and limited specific power. Additionally, Battery University notes that these batteries are not as safe as other types. Even so, their characteristics make them the popular choice for cell phones and other portable electronic devices.
LITHIUM MANGANESE OXIDE (LMO)
Lithium manganese oxide batteries are also commonly called lithium manganate or lithium-ion manganese batteries and are sometimes referred to as li-manganese or manganese spinel. The technology for this type of battery was discovered in the 1980s, with the first publication on the subject appearing in the Materials Research Bulletin in 1983. The first commercial lithium-ion cells made with lithium manganese oxide as a cathode material were produced in 1996 by Moli Energy.
Lithium manganese oxide batteries are notable for their high temperature stability and are also safer than other lithium-ion battery types. For this reason, they are often used in medical equipment and devices, but they may also be used in power tools, electric bikes and more. It is also possible to use lithium manganese oxide batteries to power laptops and electric powertrain cars.
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.
Figure illustrates the formation of a three-dimensional crystalline framework on the cathode of a Li-manganese battery. This spinel structure, which is usually composed of diamond shapes connected into a lattice, appears after initial formation.
The cathode crystalline formation of lithium manganese oxide has a three-dimensional framework structure that appears after initial formation. Spinel provides low resistance but has a more moderate specific energy than cobalt.
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). For example, the long-life version in the 18650 cell has a moderate capacity of only 1,100mAh; the high-capacity version is 1,500mAh.
Figure shows the spider web of a typical Li-manganese battery. The characteristics appear marginal but newer designs have improved in terms of specific power, safety and life span. Pure Li-manganese batteries are no longer common today; they may only be used for special applications.
Although moderate in overall performance, newer designs of Li-manganese offer improvements in specific power, safety and life span.
Most Li-manganese batteries blend with lithium nickel manganese cobalt oxide (NMC) to improve the specific energy and prolong the life span. This combination brings out the best in each system, and the LMO (NMC) is chosen for most electric vehicles, such as the Nissan Leaf, Chevy Volt and BMW i3. The LMO part of the battery, which can be about 30 percent, provides high current boost on acceleration; the NMC part gives the long driving range.
Li-ion research gravitates heavily towards combining Li-manganese with cobalt, nickel, manganese and/or aluminum as active cathode material. In some architecture, a small amount of silicon is added to the anode. This provides a 25 percent capacity boost; however, the gain is commonly connected with a shorter cycle life as silicon grows and shrinks with charge and discharge, causing mechanical stress.
These three active metals, as well as the silicon enhancement can conveniently be chosen to enhance the specific energy (capacity), specific power (load capability) or longevity. While consumer batteries go for high capacity, industrial applications require battery systems that have good loading capabilities, deliver a long life and provide safe and dependable service.
LITHIUM IRON PHOSPHATE (LIPO)
Lithium iron phosphate batteries, also known as li-phosphate batteries, use phosphate as a cathode. They benefit from low resistance properties, which enhance their safety and thermal stability.
Other benefits include durability and a long lifecycle — fully charged batteries can be stored with little change to the total lifespan of the battery’s charge. Li-phosphate batteries are often the most cost-effective option as well when their long battery life is taken into consideration. However, the lower voltage of the li-phosphate battery means that it has less energy than other types of lithium batteries.
Accordingly, these batteries are often used in electric motorcycles as well as other applications that need a long lifecycle and significant safety. Electric vehicles often use these batteries as well.
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. With most batteries, cold temperature reduces performance and elevated storage temperature shortens the service life, and Li-phosphate is no exception. 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. Figure summarizes the attributes of Li-phosphate.
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. At this point, the charge should be disconnected but the topping charge continues while driving. Li-phosphate is tolerant to some overcharge; however, keeping the voltage at 14.40V for a prolonged time, as most vehicles do on a long road trip, could stress Li-phosphate. Time will tell how durable Li-Phosphate will be as a lead acid replacement with a regular vehicle charging system. Cold temperature also reduces performance of Li-ion and this could affect the cranking ability in extreme cases.
LITHIUM MANGANESE COBALT OXIDE (NMC)
Also known as lithium manganese cobalt oxide or NMC batteries, lithium nickel manganese cobalt oxide batteries are made of several materials common in lithium-ion battery types. They include a cathode made of a combination of nickel, manganese and cobalt.
Like other lithium-ion battery varieties, NMC batteries can have either a high specific energy density or a high specific power. They cannot, however, have both properties. This battery type is most common in power tools and in powertrains for vehicles.
The cathode combination ratio is usually 60 percent nickel, 20 percent manganese and 20 percent cobalt. This means that the raw material cost is lower than it is for other lithium-ion battery options, as cobalt can be quite expensive. These batteries may come down in price further in the future, as some battery makers are planning to switch their battery chemistry to a higher percentage of nickel so that they can use less cobalt. This battery type is commonly preferred for electric vehicles due to its very low self-heating rate.
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. 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.
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
Figure demonstrates the characteristics of the 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.
LITHIUM NICKEL COBALT ALUMINIUM OXIDE (NCA)
Lithium nickel cobalt aluminum oxide batteries are also called NCA batteries, and are becoming increasingly important in electric powertrains and in grid storage.
NCA batteries are not common in the consumer industry, but are promising for the automotive industry. NCA batteries provide a high-energy option with a good lifespan, but they are not as safe as they could be compared to other lithium-ion battery types and are quite costly. The Boston Consulting Group notes that NCA batteries must be accompanied in cars by safety measures that monitor their performance and behavior to keep drivers secure.
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.
High energy and power densities, as well as good life span, make NCA a candidate for EV powertrains. High cost and marginal safety are negatives
LITHIUM TITANATE OXIDE (LTO)
The advantages of Lithium Titanate Oxide (lithium titanium oxide) battery technology are significant and the whole LTO technology is a game-changer for the entire battery industry. The LTO is bringing a new dimension of possibilities for the energy storage with a number of economical as well as ecological aspects.
the LTO is a rechargeable battery based on the, or modified from, the Lithium-Ion (li-ion) battery technology. Li-titanate oxide (LTO) replaces the graphite in the anode of the typical Li-Ion battery and forms the materials into a spinel 3D crystal structure. Having a nominal a cell voltage of 2.40V, it releases a high current discharge current that is 10 times the capacity of the other types of lithium batteries. Instead of using carbon particles on its surface as other lithium batteries do, Lithium Titanate utilizes lithium-titanate nanocrystals.
Lithium Titanate batteries' benefits range from long lifetime to enhanced safety, low-temperature performance and large potential for integration with energy storage solutions.
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 illustrates the characteristics of the Li-titanate battery. Typical uses are electric powertrains, UPS and solar-powered street lighting.
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 life span and also has the best cold temperature performance. Moving towards the electric powertrain, safety and cycle life will gain dominance over capacity. (LCO stands for Li-cobalt, the original Li-ion.)
CONCLUSION:
Different types of lithium ion batteries are studied .
REFERENCES:
https://www.explainthatstuff.com/how-lithium-ion-batteries-work.html