Rechargeable Batteries

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Rechargeable Batteries

  1. 1. Rechargeable Batteries by Thomas Hargest
  2. 2. What Are Rechargeable Batteries? <ul><li>Rechargeable batteries are batteries that can be restored to full charge by the application of electrical energy. </li></ul><ul><li>Rechargeable batteries come in different designs using different chemical reactions. </li></ul><ul><li>Rechargeable batteries are also called storage batteries or secondary cells. </li></ul>
  3. 3. Examples of Rechargeable Batteries <ul><li>Lead-acid battery: This battery is used in automobiles. The electrodes are made of lead and lead-oxide with a strong acidic electrolyte. </li></ul>
  4. 4. Lead-acid Battery <ul><li>Lead-acid batteries are the most commonly used rechargeable batteries today. </li></ul><ul><li>The chemical reactions are (charged to discharged): </li></ul><ul><li>Anode (oxidation): </li></ul><ul><li>Pb( s ) + SO 4 2- ( aq )  PbSO 4 ( s ) + 2e - </li></ul><ul><li>Cathode (reduction): </li></ul><ul><li>PbO 2 ( s ) + SO 4 2- ( aq ) + 4H + + 2e -  PbSO 4 ( s ) + 2H 2 O ( l ) </li></ul>A sealed lead acid battery
  5. 5. Examples of Rechargeable Batteries (continued) <ul><li>Nickel-cadmium battery: The electrodes are nickel-hydroxide and cadmium, with potassium-hydroxide as the electrolyte. </li></ul>
  6. 6. Nickel-cadmium Battery <ul><li>Cross-section of a classic NiCd cell. </li></ul>
  7. 7. Examples of Rechargeable Batteries (continued) <ul><li>Nickel-metal hydride battery: This battery does not contain cadmium and is used in hybrid or electric vehicles. The electrodes are nickel-hydroxide and rare earth metals, with potassium-hydroxide as the electrolyte. </li></ul>
  8. 8. Nickel-metal Hydride Battery <ul><li>The reaction occurring in a NiMH battery is as follows: H 2 O + Mm + 2e -  OH − + ½ H 2 (stored as Mm-Hx) </li></ul><ul><li>The battery is charged in the right direction of this equation and discharged in the left direction. </li></ul><ul><li>Mm stands for mischmetal (from German: &quot;mixed metals&quot;) is an unintentional alloy of rare earth elements in various naturally-occurring proportions. </li></ul>
  9. 9. Examples of Rechargeable Batteries (continued) <ul><li>Lithium-ion battery: This battery has a large ratio of power to weight and is used in high-end laptop computers and cell phones. </li></ul>
  10. 10. Lithium-ion Battery <ul><li>The anode is made from carbon. </li></ul><ul><li>The cathode is a metal oxide such as CoO 2 . </li></ul><ul><li>The electrolyte is a lithium salt in an organic solvent, such as ether. </li></ul><ul><li>Since the lithium metal is very reactive and explosive, Li-ion cells usually have built-in protective electronics and/or fuses to prevent polarity reversal, over-voltage and over-heating. </li></ul>
  11. 11. Non-rechargeable vs Rechargeable <ul><li>Non-rechargeable (primary) batteries, such as zinc-carbon batteries, are based on irreversible chemical changes that use up the materials in one or both of their electrodes. </li></ul>
  12. 12. Non-rechargeable Batteries <ul><li>Cross-section of a zinc-carbon battery </li></ul>
  13. 13. Non-rechargeable vs Rechargeable (continued) <ul><li>Rechargeable batteries are able to undergo the reverse chemical reaction changes efficiently to allow them to be restored to almost the same fully charged condition on each recharging. </li></ul>
  14. 14. <ul><li>http://science.howstuffworks.com/battery.htm </li></ul><ul><li>http://en.wikipedia.org/wiki/Rechargeable_ battery </li></ul><ul><li>http://www.sciam.com/askexpert_question </li></ul><ul><li>http://www.buchmann.ca </li></ul><ul><li>http://www.batteryuniversity.com/index.htm </li></ul>

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