Chemical, Electrical ,Mechanical and Chemistry: Li-Ion Batteries - Assignment Example

Naveed Rabbani Academia Research December 14, Project Chemistry Ans Li-ion batteries primarily use non-aqueous solutions as Lithium is highly reactive to water. Electrolytes in Lithium batteries usually compose of Lithium Salts dissolved in an organic solvent. Lithium salts such as Lithium Hexafluorophosphate (LiPF6), Lithium Tetrafluoroborate (LiBF4) or Lithium Perchlorate (LiClO4) are used with organic solvents such as Ethylene Carbonate (C3H4O3), Dimethyl Carbonate (C3H6O3), or Diethyl Carbonate (C5H10O3). Ans 2: Like most other batteries Li-ion batteries are also made of an anode, a cathode and electrolyte. The anode of Li-ion batteries is made of Carbon, usually Graphite; the cathode is made of metal oxide whereas the electrolyte is a Lithium salt as mentioned earlier. The oxidation potential of LiClO4 and LiPF6 is around 3.0 to 6.0 V in different solvents. The conductivity of the above electrolytes range from 10 mS/cm to 14 mS/cm at temperatures ranging from 68°F to 104°F. The organic solvents usually decompose on the anodes during charging but some solvents such as ethylene carbonate decompose to form a much stable solid layer on the anodes. Ans 3: The composition of Li-Polymer battery electrolyte is the same as the Li-ion except that the Lithium Salt is held in a solid polymer composite instead of the organic solvent. The common solid polymer composites used are Polyethylene oxide and Polyacrylonitrile. Some of the salts used are Lithium Perfluorosulphonimide (Li(CF3SO2NSO2CF3)) and Lithium Trifloromethane Sulfonate Salt(LiCF3SO3). Ans 4: The anode of Li-Polymer batteries is usually made of Lithium Cobalt Oxide (LiCoO2) or Lithium Manganese Oxide (LiMn2O4) whereas the cathode comprises of Lithium. The oxidation potential of these electrolytes varies from 2.7 to 4.23 V. Lithium Polymer batteries have stable ionic conductivity at high temperatures than Lithium-ion batteries hence making them suitable for long-term use in high temperature environments. The best ionic conductivity in Li-Polymer batteries is achieved when Lithium Perfluorosulphonimide salt is used in the electrolyte due to extensive charge delocalization of its anion. Most of the Li-Polymer cells must be charged carefully up to 4.2 V and they must be recharged once the voltage drops to 3.0 V. The batteries come with a variety of electrode configurations. Some of the batteries use Li metal strip as the cathode whereas as others use carbon-Li intercalation compound in which Li+ ions form a coating over a carbon cathode after first charge. The new trend for anode configuration is to use polymer such as carbon-sulphur negative electrode. Ans 5: The most obvious reason for Hyundai to use Li-Polymer batteries in their Hybrid Electric Vehicle is that these batteries can be made in any shape and size which is suitable for use in a car and they are lighter in weight as well. Secondly, they have a greater potential to store charge and hence, give longer run times so the car have a longer range once fully charged. However, they need Li-Polymer specific chargers to charge the battery and special care is required to prevent short circuit as these batteries can explode on being short circuited. Works Cited Wenige, Niemann, et al. (30 May 1998). Liquid Electrolyte Systems for Advanced Lithium Batteries (PDF). cheric.org; Chemical Engineering Research Information Center(KR). [Retrieved 14 December 2011] Advances in lithium-ion batteries, By Walter A. van Schalkwijk, Bruno Scrosati [Retrieved 14 December 2011] Balbuena, P.B., Wang, Y.X., eds. Lithium Ion Batteries: Solid Electrolyte Interphase 2004 Imperial College Press, London [Retrieved 14 December 2011] Alain Vallee; Avestor, Boucherville, Quebec, Canada. Lithium Metal Polymer Batteries: From the Electrochemical Cell to the Integrated Energy Storage System, 2004 [Retrieved 14 December 2011] Project 2: Mechanical Engineering Ans1 The elastic potential energy in a rubber band is given by: U = (1/2) (kx^2) Where U = Elastic Potential Energy k = Spring Constant (It is specific to the rubber band you are using, for instance 16 N/m for a rubber band having 0-15 cm length) x = Displacement about mean position (It depends upon the length of the rubber band) To calculate the spring constant of the rubber band, we suspend the rubber band over a hook and hang a known mass to it. From the other end, we calculate the unstretched length of the rubber band. Then we let the weight stretch the rubber band and calculate the new length. The difference in both the lengths will yield the value of displacement ‘x’. The spring constant can now be calculated by using the formula k = F/x. Where F = Applied Force. The force will be equal to the weight of the object we hung from one side of the rubber band. After getting the values for all the parameters, the elastic potential energy of the rubber band can be calculated. Ans2 The spring constant for a rubber band with length 0-15 cm is 16 N/m. To calculate the Elastic Energy, we use the afore-mentioned formula. The value of Energy stored for a single rubber band will be 0.18 Joules. In order to calculate the amount of rubber bands required to produce 1 MJ of energy, we use unitary conversion method. 0.18 Joules of energy are produced by 1 rubber band. 1 Joule of energy is produced by 1/0.18 = 5.5 rubber bands 1 MJ of energy is produced by 5.5 x 10^6 rubber bands Ans3 To design a box, I have an idea in mind. In order to devise a box that is optimized for compact space, we should have two different circular plates. The first plate contains extruded pairs of pins while the other plate has single extruded pins. The extruded pairs of pins are wrapped with a number of rubber bands in parallel combination. Both the plates are joined in such a manner that only one plate can turn or rotate and the other is static. We may consider that the plate having single extruded pins is rotating and the other is stationary. When the plate having single extruded pins is rotated, it will produce a turning effect in the rubber band, which will stretch the rubber bands and hence energy will be stored in the box. Ans4 To design a hybrid car, we may have this box engaged to a clutch and it will be attached to the engine in order to control when to store energy. The clutch should be attached to the drive shaft in order to run the vehicle. The function of a clutch is basically to engage or disengage a prime mover with the drive shaft. Ans5 The design I proposed is quite simple. It does not require any sort of thermal management. Ans6 The volumetric and gravimetric energies associated with my designed box will be dependent upon the volume of the entire box and the weight of all the rubber bands, circular plates etc. After that, we’ll calculate the energy stored in the box. The ratio of volume of the box to its weight will yield the volumetric energy while the ratio of energy stored to the weight will give us the gravimetric energy. This shows that a greater number of rubber bands will result in a greater amount of energy stored and hence greater amount of both the volumetric and gravimetric energies. The major factors governing the cost will be the circular plates and the amount of rubber bands used. Ans7 An improvement in the design could be to introduce a circular plate larger than the other two plates. The larger plate is placed between the two other plates. The larger plate contains extruded pairs of pins and it is the rotating part. The two smaller plates contain single extruded pins and are stationary. A number of rubber bands are placed at both sides of the larger plate. The larger plate is connected to the outer plates by means of a shaft. In that way, greater number of rubber bands on both sides of the shaft will result in a greater torque and greater amount of energy stored. Work Cited http://www.physicsforums.com/showthread.php?t=378342. Web. Retrieved [December 14, 2011] Project 3: Electrical Engineering Ans 1: First we must calculate the altitude of a geosynchronous orbit on which the satellite can be synchronized with the movement of the earth. The formula for calculating this altitude is R = [G x M x period2/(4 x pi2)](1/3) Where G is Newtons constant of gravity (6.61x10-11 m3kg-1s-2), M is the mass of the Earth (5.93x1024 kg), and period is 23h56m = 86160 s. (source: NASA website). This will provide the distance between the centre of the earth and the satellite orbit. Subtracting the radius of earth from this distance will give the altitude of the orbit which comes to around 42,164 km. Energy is contained in higher frequency light based on the formula E=hv where ‘h’ is Planck’s constant and ‘v’ is the frequency of light. As we go higher in the space the intensity of light will increase as the distance between the source and the light collection surface decreases. Thus the Solar Energy Density at the geosynchronous orbit level will be more than that at the surface of the earth. Ans 2: The solar panels currently used in satellites produce around 300 W/kg (source: ww.wikipedia.org). Since satellites are of varying weights that depend on the purpose of the satellites so we assume that a typical satellite weighs around 1000 kg. This means that a solar panel weighing around 1000 kg will produce 300 kW of power. Ans 3: The energy from the solar farms in the geosynchronous orbits will have to be stored in batteries that can be located in a centralized collection station. The only way feasible to bring that energy back to the ground is via unmanned space shuttles that can replace the charged battery packs in the space station with discharged ones and bring them back. But to make it economically feasible, we will have to make a giant leap in the battery technology so that the batteries can be made lighter in weight and compact yet their charging capacity must be increased manifolds so that the cost of bringing them back and forth can be reduced. Ans 4: The cost factors relevant in the case of geosynchronous solar farm are the immense fixed cost of installing the solar panels in the orbit and the design and operation of the shuttle system to bring back the charged batteries to the earth. However, since the light intensity in the space will be much more than on earth the solar panels will produce electricity with greater efficiency which will offset the cost to an extent. However, it’s a simple analysis that the main additional cost factor in the proposed solar farm is the storage of power in space and transmitting it back to the earth, which will require huge fixed and variable costs which in the case of earth based solar farms will be absent. It can be safely said that geosynchronous solar panels are a good source of power for consumers in the orbit where no mass storage/transmission is required but are not at all feasible to transmit the power back to earth. Ans 5: Since the solar panels will be stationed in space they will be subject to radiations emitting from Sun and also coming from outer space. Cosmic rays are energetic charged subatomic particles originating from outer space. They are the reason behind malfunctioning of different electronic equipments installed on spacecrafts. This is also preventing interplanetary travel of spacecrafts with crews in it. The only way to prevent from cosmic radiation is a thick shield of Lead; however, since this is not an option for the solar panels as they have to get sunlight directly, the damage from cosmic radiation will have to be incorporated as a variable cost of the project. Ans 6: The temperature difference in space varies highly from shadow to sunlight due to absence of an atmosphere. The power output of solar panels drops significantly if they are at high temperatures. However, ultra low temperatures resulting from the shadows in space will also affect the efficiency of the solar panel and their ability to produce power will decrease to a minimum level as the conductivity of metal will reduce to the decreased molecular activity of the metal used. Ans 7: We will place the solar panels facing away from the sun in an insulating box which will be open from one side, and there will be a convex glass placed in front of the open side of the box. The glass will reflect the sunlight with lower light/heat intensity. In this way the solar panels can remain cool and perform at higher efficiencies. Work Cited http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970408d.html. Web. [Retrieved 14 December 2011] Project 4: Chemical Engineering Ans1 Now a days, steam reforming is being performed from hydrocarbons to generate hydrogen in various industries. However, thermolysis and electrolysis may also be used to produce hydrogen. Ans2 The initial investment for a Steam Reforming plant mostly referred as SMR (Steam Methane Reforming, due to the fact that it utilizes methane gas in the presence of a catalyst to produce hydrogen gas) is quite high; ranging up to $1287000. The plant may produce 193.05 tons of hydrogen annually. Ans3 When water vapor is run over a piece of hot coal; hydrogen gas is produced along with carbon monoxide according to the following reaction: Increasing temperature and reducing the pressure will result in yielding more hydrogen gas. Ans4 As seen above, hydrogen gas can be produced by adding water vapor to burning coal. This hydrogen gas can be fed to a gas turbine which is coupled with the rotor of an alternator. The turbine will drive the rotor to generate energy. Ans5 To estimate the initial, operation and maintenance costs of the generator model, we’ll have to consider a few factors. I would like to start with a rough idea of how much hydrogen could be generated using a certain amount of coal and water vapor. It is evident from the chemical equation that 18 gm of water and 12 gm of Carbon produce 28 gm of Carbon Monoxide and only 2 gm of hydrogen gas. To produce approximately 0.536 tons of hydrogen daily (this accounts to 193.05 tons of hydrogen annually), we’ll require 3.216 tons of coal and 4.824 tons of water vapor. One metric ton of coal costs around $ 112 (Source globalCOAL) and a boiler to run a 4.7 MW plant for instance, would cost around $ 0.8m. The gas turbine to be used would cost around $2m. The water and other necessary equipments (feed water system of boiler, water treatment plant, fuel supply system, instrumentation etc) would cost around $4m. This would make the cost of the entire project around $ 7m to $ 7.5m. Ans6 Approximately 118 kcal of energy is required to decompose water into its constituents. We may use electrolysis to decompose water to produce hydrogen gas. The hydrogen gas thus produced would be extremely pure. The constraint to this method is that it’s an expensive process. However, on the other hand, water is present in abundance and it’s renewable too. Another method would be performing biomass gasification by superheating agricultural waste to produce hydrogen gas. In my opinion, water would be the best option to produce hydrogen gas. The process may not only be by the treatment of steam and hot coal, it may be electrolysis, photoelectrolysis or thermolysis too. Works Cited Ullmanns Encyclopedia of Industrial Chemistry by Fritz Ullmann. Print. Retrieved [December 14, 2011] www.topsoe.com. Web. Retrieved [December 14, 2011] www.Businessweekly.co.uk. Web. Retrieved [December 14, 2011] http://www.ef.org/documents/NDakotaWindPower.pdf.Web. Retrieved [December 14, 2011] Read More