Discovering Electrical & Computer Engineering. Carmen S. Menoni Professor Week 10 armain.

Transcription

1 Discovering Electrical & Computer Engineering Carmen S. Menoni Professor Week 10 armain.html

2 Lithium Ion Batteries The future of electric cars relies on the availability of batteries with sufficient capacity to store electrical energy and drive the car over long distances. Batteries could also be used in power plants for storage of energy, i.e solar or wind energy is collected and then stored for use at later time.

3 The engineering of a battery Lithium-ion batteries are rechargeable batteries History n 1991, Sony and Asahi Kasei released the first commercial lithium-ion battery. In 1989, Goodenough and Arumugam Manthiram of the University of Texas at Austin showed that cathodes containing polyanions, e.g., sulfates, produce higher voltages than oxides due to the inductive effect of the polyanion.[31] In 1996, Goodenough, Akshaya Padhi and coworkers identified lithium iron phosphate (LiFePO4) and other phospho-olivines (lithium metal phosphates with the same structure as mineral olivine) as cathode materials.[32] In 2002, Yet-Ming Chiang and his group at MIT showed a substantial improvement in the performance of lithium batteries by boosting the material's conductivity by doping it with aluminium, niobium and zirconium. The exact mechanism causing the increase became the subject of widespread debate.[33] In 2004, Chiang again increased performance by utilizing iron phosphate particles of less than 100 nanometers in diameter. This decreased particle density almost one hundredfold, increased the cathode's surface area and improved capacity and performance. Commercialization led to a rapid growth in the market for higher capacity LIBs, as well as a patent infringement battle between Chiang and Goodenough.[33] As of 2011, lithium-ion batteries account for 66% of all portable secondary battery sales in Japan.[34]

4 Lithium-ion Batteries Li-IB are organized in cells. They include sensors to controld voltage, current and temperature a&hs=nhy&sa=x&rls=org.mozilla:en- US:official&biw=1366&bih=664&tbm=isch&prmd=imvns zb&tbnid=ozbz4batfjvt5m:&imgrefurl= s.howstuffworks.com/everyday-tech/lithium-ionbattery1.htm&docid=rnthpsgqspmaum&imgurl= /static.ddmcdn.com/gif/lithium-ion-battery- 2.jpg&w=400&h=300&ei=AFCET7WcN4KS9gT0wZzRCA& zoom=1&iact=rc&dur=604&sig= &page=1&tbnh=132&tbnw=170&start=0&ndsp=21&ve d=1t:429,r:12,s:0,i:161&tx=62&ty=105

5 Lithium ion cell Inside each cell, there is a stack of materials, that make up the anode (-) and cathode (+). Sheets are submerged in an organic electrolyte. A plastic sheet with micro-holes electrically and physically separates anode and cathode while allowing ions transport. The cathode is made out of LiCoO2, the other is C.

6 Mechanisms of charging and discharging When the battery charges, ions of lithium move through the electrolyte from the positive electrode to the negative electrode and attach to the carbon. During discharge, the lithium ions move back to the LiCoO2 from the carbon. Charge movement occurs at a voltage of 3.7V

7 Li-ion batteries Li-ion batteries store 150W-hours of electricity per 1 kg of battery. This is 50% more than a Ni-metal hydride battery They hold their charge (only 5% loss in a month); do not suffer from memory effects; they can be repeatedly charged/discharged. Last 2-3 years Extremely sensitive to temperature They are ruined if completely discharged They can ignite- (this is why there are restrictions to carry more than 25 gr of Li-ion combined or equivalently 300Wh battery)

8 Li-ion batteries for different applications Equivalent Lithium Content: (ELC) Capacity of cell * 0.3 Example: 1Ah cell has 0.3 gr of Li. Laptop computer: Typically 8 cells of 2Ah each, 2 connected in parallel and 4 in series, with an ELC of 4.8 gr. Each cell produces 3.6V, with a total of 14.4 V, and 4Ah (2x2Ah) which is equivalent to approximately 60Wh.

9 State of Charge Pg. 56, IEEE Spectrum, January 2012 Electric cars and recharging: Nissan Leaf battery: 24kWh Li-ion Motor: 80KW AC synchronous motor- Range 100 miles/charge Speeds up to 90 mph] No emissions Can cover 165 Km or 100 miles for $2.75 Comes with different plug adapters for use with different class chargers

10 State of Charge Pg. 56, IEEE Spectrum, January 2012 Article discusses charging of electric cars. Typical full charge takes 7 hours with a charger that delivers 3.3KWh. At home with 120V, it takes 24 hours. There are fast charging stations The stations are classified depending on their output capabilities Level 2 (Ecotality DOE supported, private) deliver 6.2 KW available at Best Buy for $1,500. Level 1 480V 50KW Cars take DC

11 Battery care Fast charging produces heat which shortens battery lifetime. Therefore, EV are programmed to cut off fast charging at 80% charge. An approach being investigated by Nissan to replace C-electrode by Tungsten and Vanadium oxide Different technologies are being investigated for fast charging of EV. Japan leads way. US/Europe standard is different. The Nissan Leaf comes equipped with a dualsocket plug to accept any of the standards, or any rate of charge.

12 Totally electric cars: Mitsubishi I-Miev 200 Nissan Leaf Chevy Volt Tesla Roadster Plug-in Proliferates Pg. 36, Jan Batteries for these cars contain between cells per pack

13 A Battery as Big as the Grid IEEE Spectrum, Jan. 2012, pp. Batteries can also be used for energy storage. An energy storage facility is being built near the USA-Mexico border in Baja California acres manufacturing park. Storage facility will use sodiumsulfur batteries from NGK (Japan) Plant will feed a GW into the grid for 4-6 hours Presently the largest grid-based battery storage is at Fairbanks, Alaska. It can deliver 52 MW for about 15 min. Uses Li-Cd

14 What is in the future Battery storage is a expected to reach a $30B market. Advantages of batteries: no emission, no water usage, no emission, no noise. Nanotechnology into batteries Cathodes made out of nanocomposite materials to increase energy density in Li-ion Use of nano-grass to increase lifetime Aligned carbon and Si nanowires for increased storage capacity