The given assignment is all about the lithium ion batteries.
Lithium ion batteries continue to solve the problems that were experienced in the past from reliance on lead batteries to power vehicles. The lithium ion batteries have in particular made it easier to manufacture electric cars as discussed in this paper. Demand for electric vehicles is rising with estimates suggesting that there is likely to be $ 25 billion demand for electric vehicles by the year 2020 (Lighting Global 2). This then creates the need to consider technological advancements in batteries that are a source of power for the high powered electric vehicles. Lithium ion batteries are with no doubt among the key technologies that could make reliance on electric vehicles possible.
Lithium ion batteries have various capabilities including; light weight, high output performance, high energy density and ability to store energy for a longer duration. The society and economy continue to benefit from reliance on lithium ion batteries due to the fact that it is environmentally friendly (Lowe, Tokuok and Gereffi 3). With the debate on negative impacts of greenhouse gases gaining global attention, researchers identify the need to ensure innovation in technologies that reduce greenhouse gases emissions. Lithium ion batteries are among the key innovations that continue to address the need to maintain a healthy society and ensuring that the future generation is protected from the adverse effects of non-renewable sources of energy such as dependence on petroleum products for fuel. The other key benefit to the society is the fact that lithium ion batteries are less prone to explosions as a result of overcharging and overheating compared to other batteries such as lead batteries (Bandhauer, Srinivas and Thomas 3). This is because the lithium batteries have built in controllers that are responsible for regulating charging and discharging that in turn prevent overcharging and overheating. This therefore limits the possibility of accidents and damages to the environment and health of individuals exposed to the lithium ion batteries. A one-kilogram lithium ion battery produces more power that the power produced by a six-kilogram lead battery, thereby making it appropriate because of their lighter weight.
Electrical vehicles require safer batteries that can withstand higher temperatures, less prone to explosions, have higher energy density and can store a lot of energy. Rechargeable lithium ions have the capability of achieving approximately 150 Wh/kg and 400 Wh/ hr which is desirable for electric powered vehicles. The other key consideration for electric cars is the need for safety of the power battery. Lithium ion batteries make it possible to avoid damages caused on the vehicle as a result of overcharging or overheating (Bandhauer, Srinivas and Thomas 2). The battery has controllers that regulate charge and power supply such that explosion cannot occur. The properties desired in an electric vehicle could be achieved by engineers if they relied on lithium ion batteries as key source of power for the cars.
Desired functionality of lithium ion batteries include their less weight compared to lead batteries with lithium metal being the lightest metal available in the world. The battery has an improved power density such that it is able to produce large amounts of energy desirable for electric vehicles. Controllers are put in place to monitor possibility of overcharging and overheating such that reliance on lithium ion batteries gives the assurance that there will be minimal damage to the whole system (Park, Zhang and Chung 13). The lithium ion batteries have low charge loss thereby proving that they could be depended upon for a considerable period of time with ability to store a lot of energy. This means that electric cars can achieve greater mileage while depending on lithium ion batteries as their source of power.
Lithium ion batteries therefore make it possible to manufacture high powered electric vehicles by depending on phosphate ion cathodes. The lithium ion batteries therefore seek to address the concept of how engineers could depend on lighter material with capabilities of high energy density and high power capabilities to make it possible to move away from use of non-renewable and heavier sources of energy that often have low power and energy densities.
Manufacturing of lithium ion batteries involves a highly automated operation such that speed and quality are the key considerations that make a functional lithium ion battery. The key aspect to consider in the processing process is the capacity of the battery as well as the ability to cope with high temperatures (Lighting Global 4). Electric vehicles require high power which proves that lithium batteries made from phosphate cathode could significantly help in achieving the high power ambitions.
Lithium batteries made of phosphate cathodes are able to withstand high temperatures and are stable in situations where there is an overcharge and short circuiting. The internal cell safety is also, to a greater extent, assured because of safety separations that are components of algorithms and monitoring systems that prevent overcharging and overheating (Lowe, Tokuok and Gereffi 4). Lithium phosphate batteries are therefore preferred for electric vehicles since they have a higher output performance, have good performance in cars of high temperatures where they can withstand temperatures of up to 95 degree (Lighting Global 4). The fact that there are no carbon emissions from electric cars and that lithium ion phosphates adhere to environmental safety implies that the lithium ion batteries are most appropriate for the electric cars. Lithium ion batteries have higher charge and discharge capabilities that electric vehicles require which in turn makes lithium batteries preferred for the electric cars. Batteries made of lead components weigh heavily compared to lithium whereby the latter has higher storage capabilities as well as ability to produce large amounts of energy in spite of their light weight.
High energy density and high power densities are critical aspects to consider in manufacturing of electric vehicles. However, there are pros that come along with processing of high energy electric vehicles. These include the high cost involved in the process such that the cost for processing the high energy density lithium batteries is four to eight times the cost of processing lead (Park, Zhang and Chung 1). The other factor is on the safety of the lithium battery such that the high energy capacity leads to high electricity flaws in case of short circuiting. Short circuiting of the lithium ion batteries lead to a rise in temperatures of the neighboring cells such that a combustion reaction could result from the heating of neighboring Processing of lithium ion batteries involves toxic and carcinogenic substances that may be harmful to engineers tasked with the manufacturing process as well as assembling of electric vehicles.
The processing of lithium ion batteries is highly automated. The cathode, that is, phosphate ion cathode paste is spread thinly on sides of an aluminium sheet with the anode made of graphite spread on the sides of a copper coils. A separation material is sandwiched between the anode and cathode sheets. The cells is then filled with an electrolyte, that is, a lithium salt then sealed (Bandhauer, Srinivas and Thomas 3). A circuit is present in each cell to control the charging as well as discharging processes. The circuits in this case are meant to prevent discharge past a set voltage to prevent deep discharge. Lithium ion batteries therefore have three layer structure. Chemical reaction taking place inside the battery where lithium is ionized during charge and moves from layer to layer in the negative electrode. The chemical and physical structures of lithium ion batteries are therefore meant to improve functionality of the battery which in turn makes them ideal for use in electrical vehicles. During charging, the lithium ions move to the negative electrode from the positive one via the electrolyte. Electrons, therefore, flow through the opposite direction through the exterior circuit. When the charged ions stop flowing or moving, the battery is considered completely charged and ready for use. The reverse happens during discharging whereby discharged ions flow back from the negative electrode side to the positive one in the opposite directions.
Transportation and kinetics of lithium ions are positively related such that a change in a factor that affect transport also impacts on the kinetics of the ions. This then implies that the electrochemical processes within a lithium ion battery are dependent on the ability of the components to be in the desired form devoid of issues such as degraded components. Charge transport depends on various aspects including; the thickness of the separator, nature of the active elements of positive electrodes, that is, the phosphate ions cathode. The design of the battery cells is therefore affected by these factors which in turn affects the power density required from the functionality of the lithium ion battery (Han 3).
The rate of cell capability therefore depends on the transport and kinetic phenomenon in the electrochemical processes. The kinetics of the ions is affected by factors such as temperature whereby in the case of low temperatures, thermal activation is reduced leading to inability of the cell to achieve power density desired. In case of very high temperatures, there may be degradation of the electrolytes thereby limiting functionality of the batteries (Han 8). Kinetics is also affected by the thickness of electrodes such that there may be inhibited electrochemical reactions in the case where the electrodes are very thick which in turn limits transport of electrolytes along the positive electrode. It is therefore appropriate to ‘carefully consider the design of the electrodes, electrolytes as well as the temperatures in the cells so that functionality of lithium ion batteries could be improved if manufacturers are to be sure of manufacturing reliable electric cars.
I. Introduction and Motivation:
A. What is the target application of your material?
B. What are the engineering relevancies of your material system? (better, faster, cheaper, greener, etc.) How does your material system benefit the global society or economy?
C. What materials properties does your application require?
D. What is the desired functionality of your material(s) of choice?
E. What particular transport phenomena is the design of your material trying to control (this should be at an introduction level to frame the context for your audience for the parts to follow).
II. The role of processing or approach:
A. Note: You should have 5-10 references in this section to demonstrate that you have considered several different approaches in the literature to better understand your system of choice.
B. How does processing contribute to the functionality of the material?
C. Describe 2-3 processing approaches for your material or application – discuss the pros and cons of each approach, being sure to reference back to the functionality of your material.
D. Discuss the transport phenomena associated with processing, considering control over chemical, electronic, or physical structure.
E. Discuss the kinetics of your system – when is your system kinetically limited versus transport limited?
III. The math:
A. Note: This section should provide an overview of the important equations necessary to describe the transport phenomena that you will be simulating.
B. What are the definitions of each of your variables and when appropriate, provide adequate ranges.
C. How are these transport coefficients measured? (Note, you may want to move this requirement to another section, depending of the outline of your paper)
D. As your simulation will require you to use dimensionless numbers and constants, discuss how each is reduced to a dimensionless quantity (this may be best as an appendix, depending on how you frame your paper)
IV. The Simulation:
A. Using a computer program of your choice, simulate your transport phenomena in your system.
B. You should include images of at least 2 different transient behaviors (such as at very short time, at a longer time)
C. If relevant, you should include when your system reaches steady state
D. This section should also consider and articulate what you have learned from the simulation. You may find it useful to start this section with a hypothesis, then use the simulation to validate of refute your hypothesis and explain why.
V. Discussion of limitations of approach:
A. What is the uncertainty that you have in your model above?
B. What new information, in known, would advance understanding of the material system of your choice?
C. Note, well-written scientific papers typically use this section to justify why the project should continue. You want to be direct in the limitations of interpretation, but also promote a positive outlook for the future of the project
VI. Final Conclusions:
A. What is the context of the work? Why should someone care? Think about putting your work at 30,000 ft and compare with the broader field.