Fuel cells and energy, Lecture notes of Electrochemistry

Download Fuel cells and energy and more Lecture notes Electrochemistry in PDF only on Docsity! Fuel Cell - an electrochemical energy conversion device • To convert the chemicals hydrogen and oxygen into water, and in the process it produces electricity. • Battery : the other electrochemical device that we are all familiar.  A battery has all of its chemicals stored inside, and it converts those chemicals into electricity too.  This means that a battery eventually "goes dead" and you either throw it away or recharge it. For a fuel cell • Chemicals constantly flow into the cell so it never goes dead.  As long as there is a flow of chemicals into the cell,  the electricity flows out of the cell. • Most fuel cells in use today use hydrogen and oxygen as the chemicals. Attractive characteristics of Fuel Cell • High energy conversion efficiency • Modular design • Very low chemical and acoustical pollution • Fuel flexibility • Cogeneration capability • Rapid load response A functioning cell in a Solid Oxide Fuel Cell stack 1975: BEV range to charge is still only 60 miles 1979: The fuel cell golf cart 1994: Fuel cell bus 1996: GM’s EV1 2007: GM Sequel and Tesla Roadster • The adsorbed dye molecule absorbs a photon forming an excited state. [dye*] • The excited state of the dye can be thought of as an electron-hole pair (exciton). • The excited dye transfers an electron to the semiconducting TiO2 (electron injection). This separates the electron-hole pair leaving the hole on the dye. [dye*+] • The hole is filled by an electron from an iodide ion. [2dye*+ + 3I- 2dye + I3-] Dye-sensitized solar cells Ag-AgCl on Pt Thin glass membrane lon-selective membrane electrodes Pt Pt Glass Calomel electrode electrode KCl(aq) Hg, Cl, + Hg HCl(aq) Porous ceramic Solution X (a) Figure 14.17 (a) Measurement of pH using a glass electrode. (b) A crystal- membrane electrode. HCl(aq) Ag—AgCl on Pt Crystal membrane (b)