Che 20032 chemistry of technology presentation


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A presentation on the use of chemistry in some modern technological devices.

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Che 20032 chemistry of technology presentation

  2. 2. Plan of session • Timetable • Overall aims and assessment • Resources • Possible applications • Discussion of some applications • Global sustainability issues CHE-20032 Chemistry of Technology 2
  3. 3. Timetable • Lecture: 28/03/14, 14:00-16:00 (CBA 2.017) • Drop-in session to finalise poster titles , 04/04/14, 12:00-13:00 (CBA 1.074/5) • Reserve: 09/05/14, 14:00-16:00 (CBA 2.017) • Poster Session: 16/05/14, 14:00-16:00 (Multy Lab) • Planned poster size: A1 • Poster titles/topics needed by 04/04/14 • Posters to be submitted by e-mail to me as PDF files by 17:00 08/05/14 CHE-20032 Chemistry of Technology 3
  4. 4. Overall aims and assessment • To investigate the chemistry behind some modern technological applications. • To consider environmental issues (mineral resources, recycling). • To prepare and present a poster explaining a material or application in detail (25% of module). • At the poster session you will answer questions about your posters, and posters will be marked using a scheme (to be put on the KLE). CHE-20032 Chemistry of Technology 4
  5. 5. Resources • Most information will come from the web. • Web links will be listed on the slides and added to my teaching pages. • Key links will also be put on Twitter (#che20032). CHE-20032 Chemistry of Technology 5
  6. 6. Some possible topics (see also: 20084285) • Li ion batteries (mobile phones, laptops etc.) • Li air batteries • Photovoltaic materials (used in solar power) • Smart screen materials (OLED, plasma, LCD) • Solid Oxide Fuel Cell (SOFC) materials • Graphene as a silicon replacement in circuits • Lightweight materials for vehicles CHE-20032 Chemistry of Technology 6
  7. 7. Lithium ion batteries • Lithium ion batteries are widely used in mobile electronic devices from phones to laptops. • They are continually being developed and improved; some of the latest research is described here: CHE-20032 Chemistry of Technology 7
  8. 8. CHE-20032 Chemistry of Technology 8 How lithium ion batteries work – (i) • Their design is based on intercalation compounds (compounds formed by the reversible addition of ‘guest’ ions to a host lattice). • The electrolyte is a conducting polymer such as polyacetylene: n (H-CC-H)
  9. 9. CHE-20032 Chemistry of Technology 9 How lithium ion batteries work – (ii) • The anode is composed of Li embedded in graphitic carbon, forming LixC6. • The cathode is made from Li combined in an intercalation compound with a transition metal oxide like CoO2, forming LixCoO2.
  10. 10. Lithium ion battery diagram CHE-20032 Chemistry of Technology 10
  11. 11. Improvements to the lithium ion battery • There is much current research on improving the performance of lithium batteries (e.g. link on slide 7) • These have focussed on using nanostructured materials for the cathode and anode. – The rationale is that the ‘hopping distance’ for the Li+ ions is reduced. CHE-20032 Chemistry of Technology 11
  12. 12. Lithium air (oxygen) batteries (potentially higher energy density than Li ion batteries) CHE-20032 Chemistry of Technology 12 The anode is either lithium metal or a lithium containing compound. The anode is made of mesoporous carbon containing a catalyst to enhance lithium reduction from Li+ to Li. The Li+ ions combine with O2- ions at the cathode; the process is reversed on charging.
  13. 13. Photovoltaic materials • Photovoltaic materials are used in solar power devices, e.g. solar panels, to produce electric current from sunlight. CHE-20032 Chemistry of Technology 13 The photovoltaic effect is the creation of an electric current in a material when exposed to light.
  14. 14. Organic photovoltaic materials CHE-20032 Chemistry of Technology 14 Some organic photovoltaic materials A single layer photocell
  15. 15. Smart screen materials • Smart screen technology is developing fast. • The latest, including the curved screens being marketed by Samsung, use OLEDs (organic light- emitting diodes). • Other materials used include ‘plasmas’ and liquid crystals. CHE-20032 Chemistry of Technology 15 A curved OLED screen
  16. 16. OLED screens • OLEDs* work on the principle that certain organic molecules emit light when an electric current is passed through them. No backlight is required. • An example of a molecule used in OLED devices is Al(C9H6NO)3, which is often abbreviated to Alq3 CHE-20032 Chemistry of Technology 16 *PLEDs work on the same principle with polymers.
  17. 17. Solid oxide fuel cells (SOFCs) • Fuel cells convert the chemical energy from a fuel into electricity via a chemical reaction (usually oxidation). • Solid oxide fuel cells have solid oxide electrolytes, e.g. Y2O3 stabilised ZrO2. • Cathode and anode materials have particular properties as well. CHE-20032 Chemistry of Technology 17 In this example, the fuel is H2, which is oxidised by the incoming O2- ions, releasing electrons.
  18. 18. Solid oxide fuel cell materials • Research is being done to improve the performance of SOFCs – This includes improving the materials used to reduce the running temperature. – Also proton-conducting SOFCs are being developed, where protons are transported through the electrolyte instead of O2- ions, which also reduces the running temperature. CHE-20032 Chemistry of Technology 18
  19. 19. Graphene as a silicon replacement in circuits See: • Graphene is being investigated as an alternative to silicon in integrated circuits: CHE-20032 Chemistry of Technology 19 • The paper describes how the problems with using graphene in circuit design has been overcome
  20. 20. Lightweight materials for vehicles /article_04_2.html • This is a slightly less ‘chemical’ topic, but composite materials are increasingly being used in vehicle construction. – For example, the Boeing 787 Dreamliner only has 10% steel, and the rest of it is constructed from: 15% Ti, 20% Al and 50% composite materials. – (More research needed to identify ‘composite materials’!) CHE-20032 Chemistry of Technology 20
  21. 21. Rare earth (RE) elements and resource issues • The ‘rare earth’ elements are widely used in modern technological devices. They are more often called lanthanides now. • They are not all ‘rare’; Ce is the 25th most common element on the planet! • However there are supply problems with some. CHE-20032 Chemistry of Technology 21
  22. 22. The varied colours of the RE nitrates CHE-20032 Chemistry of Technology 22 Pm (promethium) is missing as it doesn’t occur naturally
  23. 23. Some applications of the RE elements • Neodymium is magnetic (10 times as powerful as iron magnets): used in computer hard drives and miniature speakers. • Dysprosium is used in control rods in nuclear reactors • Erbium is for sending signals along optical fibres – it produces light in the near IR. • Europium is used for anti-counterfeiting in Euro notes (the blue-pink stars on the €20 note contain Eu!). CHE-20032 Chemistry of Technology 23
  24. 24. Resourcing issues with RE elements CHE-20032 Chemistry of Technology 24 More than 85% of the world's supply of rare-earth metals comes from China, including almost 100% of the ‘heavy’ ones. In 2010 China started controlling output, with a dramatic effect on prices.