Lithium Ion Batteries in Electric Car

By Patrick Sobchak, Curtis Sobchak, James DiDonato


Introduction
The electric car is an automobile that can be powered by electricity. There have been many types of electric cars which use different fuel cells; however, recently there has been revitalization to the race to create a practical, economical electric vehicle. With new advances in technology, it seems that a prospect for this is the development of the electric car with a lithium ion fuel cell. As gas and oil prices remain very high, it is predicted that these vehicles will become a multi-billion dollar industry as their effect on the environment is much less substantial than a typical combustion fuelled automobile.



What are Electric Cars?
An electric car is similar to its counterpart, the combustible fuel engine vehicle; however, there are some major differences. First of all, since the engine is replaced with an electric motor in an electric car, the most notable difference is the silence of the electric car. A rechargeable battery is used to provide energy to this motor and compared to a normal vehicle; the electric car has a lot of wires instead of pipes and fuel lines. Electric powered vehicles were first created in the mid 19th century. Numerous people are attributed with the invention of electric cars. In 1828, a Hungarian man named Anvos Jedlik invented a small scale model powered by an electric motor that he designed. Other designs include a electric powered carriage created by Robert Anderson of Scotland in 1830’s ,a small scale electric car created by Professor Stratingh of Holland, and finally another small scale electric car created by Thomas Davenport of Vermont, who also invented the first American built DC electric motor. As better batteries were created, better electric cars followed as higher capacity storage batteries were needed to increase the practicality of electric vehicles. Later in the 1800s,France and Great Britain started to support the widespread development of electric vehicles. In 1899, a Belgian electric car set the world record for land speed at 68mph. America started to devote attention to electric cars in the late 1890s when A.L. Rykey and Wiliam Morrison built a six passenger, electric powered wagon in 1891. This was considered the first practical and real electric vehicle. As the prosperity of America increased at the turn of the century, cars in general became more popular. In 1899 and 1900, electric cars actually outsold all other types of cars in America. An example of an electric car at this time is the 1902 Phaeton built in Chicago by the Woods Motor Vehicle Company. It had a range of 18 miles, a top speed of 4mph, and cost $2000. The electric car enjoyed much success up until the 1920s, when the production of gasoline powered vehicles became very practical and cheap. The production of electric cars peaked in 1912 before they left the limelight. The spotlight did not return to electric cars until the 1970s and 1980s. The energy crisis of these years brought about a renewed interest in electric powered vehicles that did not rely on gasoline. Numerous electric cars were created with this renewed interest; however, none of the cars stuck and most lines were discontinued. During the 1990s, electric cars disappeared again, as the public focused on sport utility vehicles, such as SUVs and trucks, due to the relatively low prices of gasoline. In 1999, Honda created the first Hybrid, which was seen as a balance that featured a gasoline engine and an electric power train. They offered an environmentally friendly image without being hindered by the limits of the electric vehicles. The 2000s energy crisis and high prices of gasoline brought the spotlight back to electric cars, with new hybrids and electric cars being developed to fuel the demand for an environmentally friendly vehicle that did not feature a combustible engine. Automakers created many vehicles such as the Toyota Prius to fuel this demand. In 2010, Chevrolet released the Volt, which is able to travel up to 64 km on battery power alone before activating a generator which re charges the battery. Also introduced was the Nissan LEAF. This is the first all electric, zero emission five door family hatchback to be mass produced for the market. This vehicle will be based on Lithium ion battery technology.

Lithium Ion Battery Chemistry
There are numerous types of lithium ion batteries that power an electric car, but they all work on the same premise. The lithium ion battery works as an electrochemical cell. The basic electrochemistry of the cell involves only the transfer of lithium ions between two insertion electrodes, the cathode and the anode. Lithium ion batteries generally can fork out a high voltage, relative to other alkaline batteries, which explains why commercially they are so popular.

The three functional components of a lithium ion battery are the anode, cathode, and electrolyte. In most cases, the anode is made from carbon, the cathode is a metal oxide, while the electrolyte is a lithium salt in an organic solvent. However, the most commercially popular (for smaller devices eg cell phones and laptops) are : anode as graphite; cathode as lithium cobalt oxide ; and electrolyte as a mixture of organic carbonates containing complexes of lithium ions. In addition, there lies a microperforated plastic separator, which separates the anode and the cathode while still allowing ions to pass through. Depending on the materials used, the voltage, capacity, life, and safety of the lithium ion battery can change dramatically. Figure 1 shows the materials and structure of a cylindrical lithium ion battery. The most popular consumer battery is the Li-Cobalt battery. This battery, as stated, consists of a cobalt oxide cathode and a graphite carbon anode. This battery has high specific energy so it works well on cell phones, laptops, and digital cameras, but it has a relatively short life span and limited load capacities.

Figure_1.jpg
Figure 1 : Diagram of Lithium Ion Battery http://electronics.howstuffworks.com/lithium-ion-battery1.htm



The lithium Cobalt battery is not the only one on the market. In fact, there are numerous different types of lithium batteries that all share the same properties. Specifically used in cars are the Lithium Manganese Oxide, Lithium Nickel Manganese Cobalt Oxide and Lithium Iron Phosphate. These 3 are the most common types of batteries made for power tools, electric cars, and e-bikes. For the lithium manganese oxide battery, the architecture forms a 3D structure that improves ion flow on the electrode, which ends up resulting in a lower internal resistance and improves current handling. This lower cell resistance is also key to the fast charging and high current discharging. These are the main batteries used in electric cars because of their abilities to charge fast and discharge large amounts of energy.

During discharge, Li+ ions carry current from the negative electrode to the positive electrode through the solid electrolyte. During charging, and electrical power source inputs a higher voltage then that produced by the battery, causing the ions the travel in the reserve direction, from positive to negative electrodes, where they come embedded in the electrode material. Hence, the basic electrochemistry of the cell involves the transfer of lithium ions between the two insertion electrodes. Figure 2 shows this. As one can see, when the battery charges, ions of lithium move through the electrolyte from the positive electrode (cathode), to the negative electrode (anode) and attach themselves. This is aided by an external power source which moves the ions. During discharge, the lithium ions move back to the cathode from the carbon. To conclude, the lithium ions move from the anode to the cathode during discharge and from the cathode to the anode when charging the cell. Their respective equations are found below:

Discharging:
Li (aq)+ + LiCoO2 (s) -> Li2O (s) + CoO (s)

Charging:
LiCoO2(s) -> Li (aq) + + CoO2 (s)

Figure_2a.jpg
Figure 2 : Charging and Discharging of a Lithium Ion Battery and How it Works http://electronics.howstuffworks.com/lithium-ion-battery1.htm
Figure_2b.jpg
Figure 2: http://electronics.howstuffworks.com/lithium-ion-battery1.htm







Note: The movement of these lithium ions happens at a fairly high voltage, so each cell produces a voltage of approximately 3.7 V, much higher than the 1.5 volts of a typical AA alkaline cell.

Because this is an electrochemical cell, 2 redox reactions are occurring simultaneously to produce energy. One being oxidation and another reduction. By definition, the anode gets oxidized and the cathode gets reduced. We have said that the anode in this example is Carbon/Graphite, and the cathode is a layered oxide (lithium cobalt oxide). Their respective half reactions are below:

Anode:

Li+(s) + e- + 6C(s) ↔ LiC6(s)

Cathode:

LiCoO2 (s) ↔CoO2(s) + Li+(s) +e

Overall cell equation :
LiCoO2(s) + Li+(s) → Li2O(s) + CoO(s)

In a lithium-ion battery the lithium ions are transported to and from the cathode or anode, with the transition metal, cobalt , in LixCoO2 being oxidized from Co3+ to Co4+ during charging, and reduced from Co4+ to Co3+ during discharge.
In addition to this lithium cobalt battery, below is the discharging of a Lithium- Aluminum battery (figure 3). This battery is also used in cars and shows clearly the process of a discharging cell. As one can see, the current is flowing from the copper cathode to the aluminum anode, and the lithium ions are travelling to the anode through the conducting electrolyte. If this cell were to be charging, the opposite would be occurring, and the lithium ions would be depositing themselves onto the cathode with the help of an external power source.
Fig_3.gif
Figure 3 : Electron and Ion Flow In an Lithium Ion Battery http://www.evsroll.com/Lithium_Ion_Car_Battery.html







As with most batteries there is an outer case of metal. This metal is important in a lithium ion battery because of how the battery is pressurized. The metal case has pressure vent holes which relieve the pressure of the battery if it ever gets so hot that it risks explosion. The cell also has precautionary measures because lithium ion batteries can and do explode. There have been numerous reports in the past couple of years of laptops with lithium ion batteries bursting into flames. When a fire like this happens, it usually is caused by an internal short in the battery. When the separator sheet gets punctured and the electrodes touch, the battery can heat up very quickly, and potentially start a fire.

Overall, the chemistry of lithium ion batteries involves redox reactions to produce energy. The movement of lithium ions in the cell produces a lot more energy than a regular battery, which helps make these types of batteries more preferable and compact in devices such a cell phone or laptops.


Advantages and Disadvantages
Compared to the batteries used in electric cars today, such as lead acid or nickel-cadmium batteries, the lithium ion battery has many advantages and disadvantages. The first major advantage is while being lighter, the lithium ion battery has a higher energy density, which means it has a higher energy capacity. This is seen in Figure 4 (26), which has energy density on the y axis. The Lithium-Cobalt Ion, which was explained earlier, has approximately twice the energy density as the Nickel Cadmium Battery (2), while having approximately four times the energy density of a lead acid battery. This is a huge advantage as it allows the vehicle to be lighter while carrying more energy, and ultimately travel more efficiently. Another advantage of the lithium ion battery is that it has a low self-discharge. This means that the battery life is longer and maintains a higher charge. Compared to nickel-based batteries, the self-discharge of lithium ion batteries is approximately half the amount, meaning less energy is lost and wasted while the battery lasts longer (2). Additionally, one major advantage of the lithium ion battery compared to other electric car batteries is that it has low maintenance. In these batteries, no periodic cycling or discharge of the battery is needed and it also has no memory. (2) The memory effect occurs when a battery is recharged while it still has a charge in it. By doing this continuously, the capacity of the battery decreases, overall making it less efficient. (3) The advantage of the lithium ion battery having no memory means that it can be charged while it still has a level of charge left without decreasing the capacity.
energy%20density.jpg
Figure 4: Energy Density vs Type of Battery http://greenmicrotech.net/white%20paper.html

On the other hand, this battery also has many disadvantages when compared to other electric car batteries. One of these includes that lithium ion batteries can be unstable and hard to control. Because of this, manufacturers must include cooling systems that help to prevent lithium burning or flare-ups. (2) Along with the cooling system, protection circuits are needed in each lithium ion battery pack. These protection circuits supports and maintain the safe operation of these batteries by keeping the current in safe limits and limiting the maximum voltage received during charging. (2) Another problem with lithium ion batteries is deterioration due to aging. The capacity and energy density of the battery decreases as the battery ages, with lithium ion batteries commonly dying after two or three years (2). This makes it so the battery doesn’t run as efficient and must be changed frequently, which could be very troublesome if lithium ion batteries do become the dominant power supply in electric cars.

Comparisons
The Nissan LEAF vs. Combustible Engine Cars
Price: Electric cars are generally more expensive than gasoline fuelled cars. This is due to the high prices of the batteries. Currently the most affordable electric car is the Nissan LEAF, which costs roughly $32000.(4) but has numerous tax rebates such as a $7500 tax rebate. Typically midsized hatchbacks (like the LEAF) that run on gasoline are cheaper then this. The Ford Focus starts at roughly $16000. (5) while the Honda Civic starts at around $15 000 (8).

Running Costs/ Maintenance: The running and maintenance costs of an electric car are substantially less, due to the fact the in the electric motor, there are only around 5 moving parts while there are hundreds of parts in a combustible engine. An electric car also does not require some things such as oil changes or filters and even brake pads last longer in an electric car.(6) For an electric car, the first trip for scheduled maintenance is at about 40 000 miles compared to roughly 3000 miles before the oil change for a gasoline car. (7). Nissan estimates that the LEAF’s 5 year operating cost will be $1800 versus $6000 for a gasoline car. (4). However once the battery dies, it is estimated that a new battery would cost roughly $10000. (10)

Fuel Costs: “At $3.50 per gallon, a car that gets 25 miles per gallon has a fuel cost of 14 cents per mile. At $0.23 per kilowatt-hour, the Nissan LEAF has a fuel cost of 5 cents per mile.” (9). That means that it is 9 cents cheaper a mile to drive a Nissan LEAF. That would eventually add up over time and save the driver a lot of money with the electric car.

Range and Speed: The range for a gas car can be assumed to be indefinite, since it can easily be refuelled almost anywhere while the speed can almost always reach above 160 km/h. The official speed for the Nissan LEAF is just roughly 150 km/h or 90 mph and a range of roughly 100 miles per charge. Recharging of the LEAF could take anywhere from 30 min to 8 hours depending on the amount of voltage. (10)

Pollution: The Nissan LEAF has no tailpipe pollution or greenhouse gas emissions at the point of operation while any gasoline powered car will give off greenhouse gases and cause pollution.

Environmental Impact:
The mass production of ithium ion batteries for the use in electric cars will have numerous effects on the environment. Lithium ion batteries’ first major advantage, which is one of the main reasons why electric cars have become an increasingly popular topic, is the reduction of carbon dioxide into the atmosphere. Vehicles today and for the past century have been burning hydrocarbons such as petroleum for fuel; however, one of the products of this reaction is carbon dioxide. Because of the high consumption of these fuels, carbon dioxide has built up in the atmosphere and has trapped in heat from the sunlight. As more fuel is burned, the amount of heat trapped in our atmosphere has exponentially increased, producing the effect known as global warming. However, one of the ways we can stop global warming is by switching our fuel supply. Lithium ion batteries use electricity as their fuel source, and by switching the energy source from hydrocarbons to electricity, we are able to reduce and in turn stop carbon dioxide being released into our atmosphere.

Although this is very good, the lithium ion battery still has competition: other electric-car batteries. These batteries, such as the lead-acid or nickel metal hydride battery also use electricity as their energy source, and compared to the lithium ion battery, are relatively old. In comparison to these other electric batteries, the lithium ion battery poses many advantages. First of all, lithium is not as hazardous to the environment as the other metals are, such as nickel or lead. In fact, the lead used in lead-acid batteries is extremely hazardous. According to scientific studies, "long term exposure to even tiny amounts of lead can cause brain and kidney damage, hearing impairment, and learning problems in children," which is especially dangerous considering that, "the auto industry uses over one million metric tons of lead every year, with 90% going to conventional lead-acid vehicle batteries." (11) The improper disposal of other electrical batteries such as the lead-acid battery and the nickel-cadmium battery can also be toxic to the environment as these metals can contaminate soil and water. On the other hand, Kate Krebs of the National Recycling Coalition, representing the United States government, has declared lithium ion batteries non-hazardous and safe for disposal in municipal waste systems. (14) Moreover, recent developments for the lithium ion have allowed it to increase its lifetime, output, and energy density while maintaining its lost cost. In contrast to the nickel-metal hybride battery, newer lithium ion batteries have approximately three times the power density (15). This along with their higher efficiency avoid the battery from wasting electricity, which is especially important in a society where electricity could soon become the main energy source for transportation.


Even though the lithium ion battery is a lot better for the environment then other batteries, it still poses many disadvantages. First of all, producing these batteries requires many different metals that are hazardous to both humans and the environment. To create the lithium ion battery, cobalt is required (14) along with different metals for the anode and cathode depending on the type of lithium battery (12). As of now, lithium ion batteries are only used in small devices such as cell phones and music players. Even though these batteries are small, approximately 8000 to 9000 tons of cobalt is used in the production of lithium ion batteries every year. (14) What will happen when lithium ion batteries are needed in increasing amounts and in bigger sizes? The amount of different metals needed to produce these batteries may increase significantly, which can cause drastic problems for the environment. Not only will the extraction and production of these metals harm the environment, ruining countless acres of land for animals and plants alike, but the by-products of creating so much of these metals may be potentially dangerous to humans. The products from the reactions may fill up our atmosphere, harming humans even continuing global warming. Another downside of the lithium ion battery is its lifespan. Compared to other batteries such as the lead-acid, it’s life span is relatively short and the battery degrades over time, meaning more of these batteries will be needed per car, increasing the amount of metal along with production needed. (16)

If lithium ion batteries do become the battery used in future electric cars, there are additional environmental effects that must be taken note of. When recycling these batteries, they may not only contaminate human workers but also water. Questions such as when recycling, if these batteries can contaminate water or if they can create hazardous by-products may arise and be dealt with efficiently. (13) On the other hand, numerous efforts to recycle lithium ion batteries have already begun. Umicore Recycling Solutions, a company based in Belgium, has already begun the process of recycling all four metals used in lithium ion batteries (14) while the European Union has passed a battery recycling law that requires companies to reclaim 25% of the batteries they produce, including lithium ion, for recycling (14). These are promising starts for the recycling of a battery that is sure to become a major use in electric cars.

Economic Impact of Lithium Ion Electric Cars

Although electric cars have a huge impact on the environment, their economic is less substantial; however, still apparent. Many car manufacturers are in a race to create this generation’s best electrically powered automobile. First of all, the creation of electric cars adds job to the workforce. When jobs are increased, money will be poured back into the economy, which will always be a positive outcome. According to a French report, the creation of electric based automobiles would increase the workforce by 30% (17) in comparison to our normal vehicles. In addition to this, the increase in electric powered vehicles would have en effect on the fuel companies. Since analysts are not predicting a monumental decrease in gas and oil prices anytime soon, electric cars may become very popular. If electric cars became very popular, it would have an effect on the fuel companies, electricity companies, and the electric grid. The gasoline companies’ profits would likely decrease, resulting in a loss of jobs, while the electricity companies’ profits would likely increase, leading to the hiring of more employees. In addition to these, the increase of electric cars would have a huge effect on the power grid. Many experts wonder if there would be enough electricity to charge cars; however, most of the charging would be done at night, when electricity use is at its lowest. According to the U.S. Bureau of Transit Statistics, for 2006 there 135 399 945 classified automobiles, and in the future, one might expect half of these (68 million) to be electric and to be used when driving. In this scenario, the extra power required to charge all of these cars for 6 hours, which is the required time for most electric cars to fully charge, would be 136 000 MW (12kWh x 68 x 106/6 hr). In 2009, the U.S. electrical grid generated 400 000 MW of electricity, which depending on the night time power requirements to meet all the other loads on the grid, the current grid would be able to accommodate all or nearly all of the extra load. (18). However, it has yet to be seen what the effect of the electric cars themselves is on the economy. The Lithium Ion battery involved in the electric car will also have an effect on the economy. First of all, when electric cars are created on a large scale, the recycling process of the Lithium Ion battery will save a lot of money due to the value of the material remaining after the battery life time in the car is spent. For instance, a former electric car lithium ion battery could be used as a stationary storage station, since after the battery is not suited for use in a car anymore, it still has 80% of its charging capacity. (19). It is estimated that the Lithium ion battery market will become a multi billion dollar market, due to the steady rise of fuel prices and the advantages of these batteries. Nissan and NEC will jointly spend about $194 million for the world’s first mass production of lithium ion batteries for hybrid and electric cars, which will no doubt lead to the creation of numerous jobs. The companies plan to build a plant capable of making enough batteries for 60 000 electric cars a year. (20) In the future, lithium ion batteries may become economical enough and have a long enough run time to be practical for electric cars and replace today’s lead acid batteries. Also, compared to the standard nickel cells that are used in cars now, lithium ions batteries are cheaper and can store almost twice the amount of energy. This will make the new battery more accessible to the public and easier to replace. (21)



For the Future
The recent developments in the lithium ion battery have created a huge market for electric cars. With the increase in awareness of global warming along with overwhelming prices of fuel and gasoline, electric cars and lithium batteries have enormous potential to become the transportation of the future. It is believed that in the next ten years, the Lithium Ion battery market will increase by four times, expanding from $11 billion USD in 2010 to $43 billion USD by 2020 (22). All around the world, companies are expanding their research and products to include Lithium Ion Batteries. LG Chem, a company based in South Korea, has plans to build factories in South Korea and the United States that can potentially manufacture lithium ion batteries for around 350,000 vehicles annually (22). Also in the US, the federal government has helped fund 26 of 30 electric vehicle plants, including the recent funding of nine Lithium Ion plants (22). These stats help to demonstrate the growth and potential of the Lithium Ion market and show how strong automobile countries such as South Korea and the US are taking interest in this new technology. As one can see, the lithium ion battery has a bright future in our rapidly evolving society. Perhaps within the next few decades, we will see the end of pollution due to transportation and have these advanced cells as our means of travel.



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