13th March 2014
Lithium Ion Batteries Materials
The world revolves around energy. It comes in many forms: sun (solar), wind, water, fire and earth (minerals). Over centuries humans learned how to harness energy and built devices that allow the energy to transfer into work. One of these devices is the battery; it holds great value in today’s society. In regards to the battery, the Lithium Ion Battery contributes towards the technological advances of the future. The Lithium Ion Battery consists of the same materials as a regular battery, but there are additional materials as well. “Lithium is the lightest of all metals, has the greatest electrochemical potential and provides the largest specific energy per weight” (Understanding Lithium-Ion). This research consists of the detailed analysis on materials in the Life Cycle of a Lithium Ion Battery.
In order to understand about the materials in the life cycle of the Lithium battery, it is important to understand it entirely. The most basic form is the battery; Lawrence Berkeley National Laboratory informs, “Batteries are devices that convert stored chemical energy into useful electrical energy…In a battery, the overall chemical reaction is divided into two physically and electrically separated processes: one is an oxidation process at the battery negative electrode wherein the valence of at least one species becomes more positive, and the other is a reduction process at the battery positive electrode wherein the valence of at least one species becomes more negative…In the case of the rechargeable battery, the electrochemical oxidation-reduction reactions are reversible at both electrodes. The battery functions by providing separate pathways for electrons and ions to move between the site of oxidation and the site of reduction.” The Lithium ion battery is one kind of rechargeable battery. The Lithium-ion battery is built of a “casing, chemistry, electrolyte, and the internal specialized hardware” (Hagopian). The core of the Lithium-ion battery is the Lithium itself, usually combined with other elements like Cobalt, Manganese, Iron, Nickel, and Aluminum.
Batteries in general are potentially harmful, and it is the same for the Li-ion battery. A “short circuit, overcharge, over-discharge, crush, and high temperature can lead to thermal runaway, fire, and explosion” (Daniel). Although the Li-ion has risks with its use, there are many advantages compared to the disadvantages. The following advantages are; no liquid electrolyte meaning there is no leaking hazard, high power density, light weight, fastest charge possible, long lasting, no reconditioning needed, available in wide range cell constructions, and many more. Some of the disadvantages or shortcomings are the high cost battery compared to lead acid batteries, stricter shipping regulations: temperature, ventilation, capacity loss, degradation, the measurement of the state of charge is more complex, and the stability-although the Lithium polymer cells with the solid electrolyte overcomes that problem (Battery and Energy Technologies). Li-ion batteries considerably have more benefits than the shortcomings, therefore are well used in today’s society.
From the Lawrence Berkeley National Laboratory’s personal research on the Li-ion battery, they created the Life Cycle of the Lithium-Ion battery specifically in relation to electric and hybrid vehicles. Still, the life cycle is the same in all cases of the life process of Li-Ion batteries. The Life cycle is divided into six categories; first Upstream Material Extraction, Materials Processing, Components Manufacture, Product Manufacture, Product Use, and End of Life. There are lots of materials within each of the parts of the life cycle. The following research will elaborate on the materials in each section.
In the Upstream Material Extraction there are numerous raw materials and many different ways to combine the materials. Here are the main materials for the upstream process:
Anode: Battery Grade Graphite, Copper Foil, Cathode: Aluminum, Lithium Manganese oxide, Lithium-Nickel Cobalt Manganese oxide, Lithium Iron phosphate, Lithium Chloride extraction, Anode/Cathode: Polymer binder, Auxiliary Solvent, Separator: Polyolefin, Casing: Aluminum, Polypropylene resin -pouch material-, Electrolyte: Lithium hexaflourophosphate, Ethyl carbonate, Lithium fluoride, Phosphorus pentachloride, Lithium chloride extraction, BMS: Copper wiring, Steel, Printed Wire Board, Pack Housing: Polyethylene terephthalate, Passive Cooling System: Steel, Aluminum , and the Collector: Copper, Aluminum (Lawrence Berkeley National Laboratory).
A large effort is really put into extracting the raw materials and separating them into their respective places. Understanding the parts of the Lithium-Ion battery is important as well. Starting of with the anode: most of the materials are lithium, graphite, lithium-alloying materials, intermetallics, or silicon (Daniel). The anode is a required part in creating the Li-ion battery.
“The anode consists of the negative electrode of the battery. Anodes are typically composed of a powdered graphite material, which is combined with a binder and coated on copper foil (Gaines and Cuenca, 2000; Electropedia, 2011)… During the anode manufacturing process, a solvent is also typically used to develop the slurry anode paste, which is then coated on the foil and dried. Because the solvent is an ancillary material that does not become part of the battery cell, it may be recovered and reused” (Lawrence Berkeley National Laboratory).
Another part of the Li-ion battery is the cathode, unlike the anode; the cathode is the opposite in charge. The anode being a negative electrode, the cathode is a positive electrode. The cathode is also bound to binder material to create a slurry paste. Methods of coating the material have been introduced that make up for the poor conductivity, but it adds some processing costs to the battery (Daniel). The anode and cathode are the opposites in the Li-ion battery and there is the separator that keeps the two apart. The separator is made of polyolefin, and it keeps the anode and cathode separated in the battery cell “after they are wound together” (Lawrence Berkeley National Laboratory). The battery separator is physically important that it “separates the two electrodes from each other, thus avoiding a short circuit” (Daniel). Without the separator the battery would become a threat.
After the separation between the anode and cathode, there is the conductor of the two, and that is he electrolytes. This solution is the conductor of the Lithium-ions between the anode and cathode. It is composed of Lithium salts and ethylene carbonate as the organic solvent. The electrolyte needs to be strong and “withstand existing voltage and high temperatures and that has a long shelf life while offering a high mobility for lithium ions… The most important consideration is their flammability; the best performing solvents have low boiling points and have flash points around 30°C. Therefore, venting or explosion of the cell and subsequently the battery pose a danger. Electrolyte decomposition and highly exothermic side reactions in lithium-ion batteries can create an effect known as “thermal runaway.” Thus, selection of an electrolyte often involves a tradeoff between flammability and electrochemical performance” (Daniel), even in the process of building the battery there are hazards and risks involved. As a safety, “Separators have built-in thermal shutdown mechanisms, and additional external sophisticated thermal management systems are added to the modules and battery packs” (Daniel). All of the components within the battery are key, but the casing -that holds everything together- is just as essential. The casing is typically made up of light plastic, its better if the battery is lighter, also another important function to the battery is the BMS, the battery management system; this is all the circuitry, internal/external connections, and wires to keep the battery working.
Material processing is the next part of the life cycle; component manufacturing can be joined with material processing as well. There are increased “Efforts in materials processing and manufacturing to increase performance and to manage unavoidable volume change… leading toward composite materials with micro- and Nano scaled particles” Daniel). The movement towards Nano particles is a continued effort in research. Starting from the already created parts of the Li-ion battery,
“The components are then stacked to separator-anode-separator cathode stacks followed by winding to cylindrical cells, insertion in cylindrical cases, and welding of a conducting tab. The cells are then filled with electrolyte. The electrolyte has to wet the separator, soak in, and wet the electrodes. The wetting and soaking process is the slowest step and therefore is the determining factor in the speed of the line. All other needed insulators, seals, and safety devices are then attached and connected. Then, the cells are charged the first time and tested. Often cells have to be vented during the first charge. First charging cycles follow sophisticated protocols to enhance the performance, cycling behavior, and service life of the cells. Recently, efforts have been made in combined and hybrid processing, such as direct deposition of separators onto electrodes and rapid heat treatments” (Daniel).
All this testing is required in order to prevent safety hazards and to make sure the product functions properly. Time, effort and work are never-ending processes when creating Li-ion batteries.
The next step of the Lithium-Ion battery life cycle is product manufacture and product use. The battery is already made and now sending the battery to different its consumers is the vital part of this process. Shipping and handling the material is important and careful process. The temperature of the shipment has to be regulated and the pressure and how the material is sent to its consumers are important as well. Once the battery is sent to the main consumers, as in the large companies, then the product can be rearranged into different types of products. The Lithium-ion battery s not only used for electric/hybrid vehicles, but also for cellphones and other electrical devices used in everyday life. Once the consumer has their product in hand, the battery is used till its end of life, “Generally, rechargeable batteries are charged by a battery charger having a power supply that can provide a supply of DC current. A rechargeable battery accepts the electrical current and converts it into chemical energy” (Rechargeable Battery). Usually rechargeable batteries last about more than ten years, or if the consumer no longer needs to use his or her product, it is then thrown away to landfill, and reprocessed in the factories.
The end of life process is a very large procedure with many factors that branch out of the recycling process. There are the following three processes that separate the raw materials apart to be used again. The Hydrometallurgical Recovery Process, the Pyrometallurgical Recovery, and the Direct Recycling Process. The Hydrometallurgical Recovery Process,
“Can be applied to a variety of lithium battery chemistries. Under this process, the batteries are first collected, inspected, and sorted by chemistry. Next, the batteries are fed via a conveyer belt to a hammer mill to remove the paper and plastic. Once prepared, the batteries are processed in a tank, using a feed of alkali process solution (lithium brine) to further shred the cells. The materials are then separated to recover the scrap metal and remove any other non-metallic materials (Lawrence Berkeley National University).
From this process, these are the resulting materials; Copper cobalt product -mixture of Copper, Aluminum, Cobalt-, Cobalt filter cake -mixture of Cobalt and Carbon-, Li-ion fluff -mixture of some plastics/steel-, Lithium brine -dissolved electrolytes and Lithium salts.
Hydrometallurgical processing is one form of recycling. The second process is the Pyrometallurgical Recovery, and it
“Relies on a high-temperature smelting process to recover the metals and other materials. This process allows recycling of a variety of end-of-life (EOL) lithium-ion batteries based on different chemistries. Under this process, the unsorted and untreated EOL batteries are fed into a high temperature smelter, where the scrap is heated to temperatures of 1,250 degrees Celsius in an oxygen environment. Through the smelter process, the metal oxides are converted to their metallic form, a molten metal alloy (e.g., containing cobalt and nickel). The metal alloy is further refined for use as new battery cathode material. The slag generated by the smelting process contains lithium…” (Lawrence Berkeley National University).
The Pyrometallurgical Recovery and Hydrometallurgical Recovery use a lot of energy and most work; the third option in recovery is the Direct Recycling Process. These are the steps,
“Under the direct recycling process, the battery components are first separated using physical and chemical processes to recover the metals and other materials. Next, to generate materials suitable for reuse in battery applications, some of the recovered materials may need to undergo a purification or reactivation process. The direct recycling process, which is still in the pilot stage, may allow for a higher percentage of recovered battery materials” (Lawrence Berkeley National Laboratory).
The “refurbished” materials can be reused in the Lithium-Ion Life Cycle again, and also can be used in other applications, such as computers, and other electronic devices. The Lithium-Ion battery cycle is notably very well organized and created. All aspects of the life cycle try to use the least amount of energy and save most of the material for the next life cycle. Researchers are still continuously doing their best to fine-tune the process for the betterment of life, even though the process may not pollute the environment as much as other processes, it is still better to decrease the risks. The Lithium-Ion Battery Life Cycle has many steps to its process and materials and refinements, but it is considered as a valued part of consumer products.
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Lithium-Ion Batteries Waste
Rechargeable batteries provide energy for many electronics and machines and are often preferable to traditional batteries. Because rechargeable batteries can be reused even after a full discharge, they are often cheaper and environmentally preferable to traditional disposable batteries. Rechargeable batteries utilize two electrodes, an anode and a cathode, and an electrolyte to return the negative charge to the cathode after discharge. Different batteries utilize different anodes, cathodes, and electrolytes; one particular rechargeable battery, the lithium-ion battery, is mostly composed of lithium, aluminum, cobalt, and copper, with small amounts of nickel, manganese, and copper (Kang et al., 2013). While lithium-ion batteries do not include highly toxic materials, such as cadmium or mercury, they still have the potential to cause environmental harm when disposed of improperly. However, the vast majority of lithium-ion batteries are not recycled, and the American National Recycling Coalition has even listed lithium-ion batteries as safe for landfills. Some scientists argue that lithium-ion batteries should be considered unsafe for landfills, and they often advocate for the required recycling of lithium-ion batteries. However, the environmental impact of lithium-ion batteries extends well beyond their disposal. In addition to the potential waste created from disposal of batteries, the extraction of metals, production of lithium-ion batteries, and use of lithium-ion batteries all produce waste as well.
The mining of all metals poses a threat to the surrounding environment due to risk of acid leaching, landslides, metal contamination, and habitat destruction. In situ leach mining is a common technique used to extract metals from ore, as it does not disturb the surface of the rock and leaves no solid waste from the rock. However, this method uses strong acids, which dissolve the other metals in the rock; the fluid given off contaminates nearby groundwater and surface water, and can lower the pH of the surrounding environment. (International Atomic Energy Agency, 2005). Open-pit mining consists of direct extraction of metals from an open pit. This form of mining exposes old rock, which can release radioactive materials, asbestos, and metallic dust. Underground mining can lead to landslides or tunnel collapse. Additionally, mercury is often used in underground mining to react with precious metals, such as cobalt, which makes extraction easier; the excess mercury can enter the atmosphere or water supplies, creating a worrisome environmental and health hazard (Miranda et al., 1997). There are regulations for how much mercury can be emitted, but any amount is harmful to the environment and the health of nearby humans.
Fortunately, many countries have laws and regulations to prevent the contamination and destruction due to metal mining. For example, the United States caps the amount of waste that can be produced from mining sites. These standards differ based on the method of mining, but their overall goal is to minimize the environmental impact of mining. However, many mines in the United States exceed the maximum waste permissible by the National Environmental Policy Act. In a study of 24 American mines, 21 exceeded the set standard of permissible waste (Maest et al., 2006). Even worse conditions can be found in less developed countries; in Peru, only five of the 200 mining companies follow the nations mine safety laws. This poses a threat not only to the environment, but also to the people who work in the mines. In the mining town of La Rinconada, the life expectancy is 50 years, compared to the Peruvian national average of 71 years (Larmer, 2009). The lithium, cobalt, nickel, and other metals in Lithium-Ion batteries may come from environmentally unsafe mines, and the mining of these metals in underdeveloped areas negatively impacts the workers and local citizens. It is clear that developed countries only invest in environmental safety when it affects their own country; the destruction of the environment and health of developing countries is not considered. Even worse, lithium is almost exclusively imported from China due to China’s low regulation on environmental safeguards (Bradsher, 2009). The lithium must be transported extremely long distances to the United States or Europe, which requires the use of fossil fuels.
The production of lithium-ion batteries comes with its own set of wastes. The production of most lithium-ion batteries results in approximately 60-70 kg/kWh of CO2 (figure 1). The production also required approximately 300-350 Mcal/kWh (figure 2). The exception was the lead-acid battery, which had significantly lower emission rates and energy consumption. However, most batteries for commercial use are nickel-cobalt. Generally, N-methyl-2-pyrrolidone is used as the solvent for the electrolyte; however, it is environmentally sound to use water as a solvent as opposed to N-methyl-2-pyrrolidone. Unfortunately, the use of water as a solvent slightly lowers the battery life, so use of N-methyl-2-pyrrolidone is often preferred. Recent advances in lithium-ion battery production have allowed environmental impacts from production to fall almost to environmental impacts from battery use; use phase environmental impacts have historically been much lower than production phase impacts in batteries (Zackrisson, 2010).
Essentially, the only waste from lithium-ion batteries results from the recharging of the batteries and the hazards associated with rechargeable batteries. In California alone, the recharging of batteries accounts for approximately 8,000 gigawatt hours of energy. However, because battery chargers are relatively inefficient, essentially only one-third of the 8,000 gigawatt hours of energy are used to power the battery; this equates to nearly 2 million metric tons of carbon emissions (Report 1). Chargers for lithium-ion batteries in electric vehicles may have their own carbon emissions. However, the overall carbon emissions from electric vehicles are still significantly lower than that of conventional vehicles (Jerew, 2013). The inherent hazards associated with lithium-ion batteries can also be a cause of waste. The cell of the lithium-ion battery can rupture or combust due to overheating or overcharging. The battery can catch on fire due to short-circuiting; however, this can only happen if the battery has a faulty safeguard. There is also a risk of fire due to highly pressurized electrolytes if the battery has faulty packaging. These incidences not only release harmful chemicals, such as cobalt or lithium, into the environment, they can also be an immediate danger to human health and safety.
Improper disposal of batteries can also have environmental and health impacts. A study by Kang et al. determined that all lithium-ion batteries should be considered hazardous waste under California’s Universal Waste regulation. The study found that lithium-ion batteries have excessive levels of cobalt, copper, and rarely nickel. Additionally, some lithium-ion batteries were found to have levels of lead that exceeded those allowed by United States regulation. The European Union has a law in place requiring vendors to provide incentives to costumers to recycle their batteries; however, this is a resources decision as much as it is an environmental one. An estimated 8,000-9,000 tons of cobalt are used in lithium-ion batteries every year; cobalt, along with the other metals in lithium-ion batteries, are limited metals that currently cannot be retrieved once in a landfill (Mitchell, 2006).
There are two overarching techniques used to recycle lithium-ion batteries: physical processes and chemical processes. Physical processes consist of mechanical separation and thermal treatment. Mechanical separation is generally used to treat the outer casing and shells of the battery to isolate different metals. Mechanical processes include crushing the metals down, sieving the metals to separate them by size, and magnetic separation to separate them by conductivity. However, mechanical processes generally cannot fully separate the different metals, so it often precedes thermal treatment. Thermal treatment consists of heating up the metals to their individual melting points to separate from the battery. As the metals reach their melting points, they can be extracted before the other metals melt. Thermal treatment cannot capture carbon and organic compounds; these require chemical processes. Chemical processes are a series of steps in which the metals are leached into an acidic or basic bath. The leached metal can then be bounded to an organic material. From there, the metal can be extracted form the organic material and has successfully been recovered from the battery (Xu et al., 2008).
The recycling of lithium-ion batteries comes with a set of challenges. There are inherent risks when recycling batteries. In 2009, a lithium battery-recycling factory in Vancouver caught fire, releasing unknown amounts of toxic material into the air. This was due to a failure to combine fluorine from the batteries with calcium, an unreactive material; the fluorine then reacted with hydrogen, making a highly acidic compound. The same factory had also experienced five previous fires (Anderson, 2013). Additionally, lithium-ion batteries are relatively cheap to make, and don’t provide much return when recycled. The economic value of recycling one ton of lithium-ion batteries is approximately $100 (Mitchell, 2006)—not a particularly convincing value considering how much recycling can cost. However, policy-makers do not appear to be taking into consideration the potential damage that millions of improperly disposed batteries can do to the environment and human health. Regardless of the scientific evidence, the federal government still classifies lithium-ion batteries as non-hazardous waste (Mitchell, 2006).
For all of these reasons, the recycling rate of lithium-ion batteries is less than 30% in Japan. The reasons listed were predominantly that the consumer “did not think it was necessary” or “did not even think about it” (Asari et al., 2013). 70% of lithium-ion batteries in Japan are being disposed of improperly without a second though; this number is likely much higher in the United States, where sending lithium-ion batteries to landfills is legally considered safe.
There still exists a great deal of uncertainty regarding the environmental impacts of lithium-ion batteries. While many European countries deem lithium-ion batteries environmentally unsafe, the United States labels lithium-ion batteries as environmentally safe. Additionally, research exists that counters the United States’ stance on lithium-ion batteries; the studies by Kang et al. found that many metals found in lithium-ion batteries, including cobalt, nickel, copper, and lead. The report by Kang et al. heavily recommended that lithium-ion batteries be listed as unsafe materials in California. However, additional research may be needed to determine how much, in any, of the harmful metals are exiting the landfills and entering the environment. There also appears to be very little information on the waste emitted from the production of lithium-ion batteries. It is clear that carbon dioxide emissions and energy consumption exist during the production of lithium-ion batteries. However, the emissions and energy use vary greatly depending on the metals used in the anode and cathode of the battery; the lead-acid battery used less energy and emitted less carbon dioxide than it’s counterparts, but it would need to be recycled if mass-produced due to the environmental toxicity of lead. The recharging of batteries also uses large amounts of energy and, therefor, carbon dioxide. In fact, two-thirds of the energy used for recharging batteries is used inefficiently. More efficient battery chargers could help reduce energy use and carbon dioxide emissions.
Regardless of the environmental impact of lithium-ion batteries, the metals used in them are finite and must be recycled. Metals such as cobalt, nickel, and lithium are considered “precious” metals and may be in short supply in the future. The recycling of lithium-ion batteries, through physical or chemical methods, would help retrieve and large percentage of these limited resources. While the recycling of lithium-ion batteries may not pass a conventional cost-benefit analysis, the vitality of these resources and their environmental impacts cannot be ignored.
Lithium-Ion Batteries are a great alternative to disposable alkaline batteries and other, more toxic rechargeable batteries. However, lithium-ion batteries are far from perfect, and there are many steps that can be taken to improve them. A viable, mass-producible lead-acid lithium-ion battery would help cut carbon emissions and energy use immensely. Battery chargers must become more efficient as to prevent the waste of energy. Lithium-ion batteries must be labeled as environmentally unsafe, and their recycling must be enforced. And, perhaps most importantly, the mining of all metals must be regulated in foreign countries; the health and environmental impacts of unsafe mining conditions are not worth the cost saved. Ideally, countries would utilize metals from nearby as much as possible to reduce the cost of transportation. The lithium-ion battery has the potential to become one of the world’s most environmentally friendly batteries; there are just some vital regulations that must be put in place.
Figure 1 (Ishihara et al., 2013)
Figure 2 (Ishihara et al., 2013)
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