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ARTICLES IN THE BOOK

  1. AAAA battery
  2. AAA battery
  3. AA battery
  4. A battery
  5. Absorbent glass mat
  6. Alessandro Volta
  7. Alkaline battery
  8. Alkaline fuel cell
  9. Aluminium battery
  10. Ampere
  11. Atomic battery
  12. Backup battery
  13. Baghdad Battery
  14. Batteries
  15. Battery charger
  16. B battery
  17. Bernard S. Baker
  18. Beta-alumina solid electrolyte
  19. Betavoltaics
  20. Bio-nano generator
  21. Blue energy
  22. Bunsen cell
  23. Car battery
  24. C battery
  25. Clark cell
  26. Concentration cell
  27. Coulomb
  28. 2CR5
  29. Daniell cell
  30. Direct borohydride fuel cell
  31. Direct-ethanol fuel cell
  32. Direct methanol fuel cell
  33. Dry cell
  34. Dry pile
  35. Duracell
  36. Duracell Bunny
  37. Earth battery
  38. Electric charge
  39. Electric current
  40. Electricity
  41. Electrochemical cell
  42. Electrochemical potential
  43. Electro-galvanic fuel cell
  44. Electrolysis
  45. Electrolyte
  46. Electrolytic cell
  47. Electromagnetism
  48. Electromotive force
  49. Energizer Bunny
  50. Energy
  51. Energy density
  52. Energy storage
  53. Flashlight
  54. Float charging
  55. Flow Battery
  56. Formic acid fuel cell
  57. Fuel cell
  58. Fuel cell bus trial
  59. Galvanic cell
  60. Gel battery
  61. Grove cell
  62. Half cell
  63. History of the battery
  64. Hybrid vehicle
  65. Lead-acid battery
  66. Leclanché cell
  67. Lemon battery
  68. List of battery sizes
  69. List of battery types
  70. List of fuel cell vehicles
  71. Lithium battery
  72. Lithium ion batteries
  73. Lithium iron phosphate battery
  74. Lithium polymer cell
  75. LR44 battery
  76. Luigi Galvani
  77. Manganese dioxide
  78. Memory effect
  79. Mercury battery
  80. Metal hydride fuel cell
  81. Methane reformer
  82. Methanol reformer
  83. Michael Faraday
  84. Microbial fuel cell
  85. Molten carbonate fuel cell
  86. Molten salt battery
  87. Nickel-cadmium battery
  88. Nickel-iron battery
  89. Nickel metal hydride
  90. Nickel-zinc battery
  91. Open-circuit voltage
  92. Optoelectric nuclear battery
  93. Organic radical battery
  94. Oxyride battery
  95. Panasonic EV Energy Co
  96. Peukert's law
  97. Phosphoric acid fuel cell
  98. Photoelectrochemical cell
  99. Polymer-based battery
  100. Power density
  101. Power management
  102. Power outage
  103. PP3 battery
  104. Primary cell
  105. Prius
  106. Proton exchange membrane
  107. Proton exchange membrane fuel cell
  108. Protonic ceramic fuel cell
  109. Radioisotope piezoelectric generator
  110. Ragone chart
  111. RCR-V3
  112. Rechargeable alkaline battery
  113. Reverse charging
  114. Reversible fuel cell
  115. Searchlight
  116. Secondary cell
  117. Short circuit
  118. Silver-oxide battery
  119. Smart Battery Data
  120. Smart battery system
  121. Sodium-sulfur battery
  122. Solid oxide fuel cell
  123. Super iron battery
  124. Thermionic converter
  125. Trickle charging
  126. Vanadium redox battery
  127. Volt
  128. Voltage
  129. Voltaic pile
  130. Watch battery
  131. Water-activated battery
  132. Weston cell
  133. Wet cell
  134. Zinc-air battery
  135. Zinc-bromine flow battery
  136. Zinc-carbon battery
 



BATTERIES
This article is from:
http://en.wikipedia.org/wiki/Zinc-air_battery

All text is available under the terms of the GNU Free Documentation License: http://en.wikipedia.org/wiki/Wikipedia:Text_of_the_GNU_Free_Documentation_License 

Zinc-air battery

From Wikipedia, the free encyclopedia

 

Zinc-air batteries, also called “zinc-air fuel cells,“ are non-rechargeable electro-chemical batteries powered by the oxidation of zinc with oxygen from the air. These batteries have very high energy densities and are relatively inexpensive to produce. They are used in hearing aids and in experimental electric vehicles. They may be an important part of a future zinc economy.

Particles of zinc are mixed with an electrolyte (usually potassium hydroxide solution); water and oxygen from the air react at the cathode and form hydroxyls which migrate into the zinc paste and form zincate (Zn(OH)42–), at which point electrons are released and travel to the cathode. The zincate decays into zinc oxide and water is released back into the system. The water and hydroxyls from the anode are recycled at the cathode, so the water serves only as a catalyst. The reactions produce a maximum voltage level of 1.65 volts, but this is reduced to 1.4–1.35 V by reducing air flow into the cell; this is usually done for hearing aid batteries to reduce the rate of water drying out.

The term zinc-air fuel cell usually refers to a zinc-air battery in which zinc fuel is replenished and zinc oxide waste is removed continuously. This is accomplished by pushing zinc electrolyte paste or pellets into an anode chamber. Waste zinc oxide is pumped into a waste tank or bladder inside the fuel tank, and fresh zinc paste or pellets are taken from the fuel tank. The zinc oxide waste is pumped out at a refueling station and sent to a recycling plant. Alternatively, this term may refer to an electro-chemical system in which zinc is used as a co-reactant to assist the reformation of hydrocarbon fuels on an anode of a fuel cell.

Zinc-air batteries have properties of fuel cells as well as batteries: the zinc is the fuel, the rate of the reaction can be controlled by controlling the air flow, and used zinc/electrolyte paste can be removed from the cell and replaced with fresh paste. Research is being conducted in powering electric vehicles with zinc-air batteries.

Reactions of Zinc-Air "Battery"

Anode: Zn + 4OH → Zn(OH)42– + 2e (E0 = –1.25 V)

Fluid: Zn(OH)42– → ZnO + H2O + 2OH

Cathode: O2 + 2H2O + 4e → 4OH (E0 = 0.4 V)

Overall: 2Zn + O2 → 2ZnO (E0 = 1.65 V)

Alternatively the reaction is stated without use of zincate, but this is inaccurate:

Anode: Zn + 2OH → Zn(OH)2 + 2e (E0 = –1.25 V)

Cathode: O2 + 2H2O + 4e → 4OH (E0 = 0.4 V)

Overall: 2Zn + O2 + 2H2O → 2Zn(OH)2 (E0 = 1.65 V)

Properties of Zinc-Air Battery

  • Zinc-air batteries have very high specific energy compared to other batteries (110 to 200 W·h/kg or 400 to 720 kJ/kg)
  • Zinc-air batteries put out continuous energy as they dissipate their energy, and the voltage does not drop until the battery is over 80–85% depleted.
  • Zinc-air batteries have very long shelf lives, as long as they are sealed (no oxygen is let in) until they are activated for use.
  • Zinc-air batteries have a very high self-discharge rate when exposed to air, as the zinc will spontaneously react with oxygen, and the water catalyst in the battery will tend to dry out.
    • To prevent self-discharging the battery has to be resealed when not in use. Moisture in the battery can be maintained with use of a humidified environment.
    • Zinc-air batteries must not be over saturated with water, though. Avoid immersing in water!
  • Zinc-air batteries use cheap materials and can be produced in mass quantities inexpensively.
  • Zinc-air batteries are not electrically rechargeable, but the zinc can be recycled or “mechanically recharged;” the zinc oxide from the used batteries is melted back into zinc metal (and thus reduced) and remixed with recycled electrolyte.

See also

  • Hydrogen technologies

References

  • Brief overview of Zinc-air batteries
  • Zinc-air powered buses
  • Military uses of Zinc-air Batteries
  • Zinc-Air Batteries for UAVs and MAVs (includes half-cell reactions)
  • Incorrect Zinc-air reaction
  • Zinc-air fuel cell
  • Procedure to MAKE a simple Zinc-air fuel cell as a science fair project.
  • A European company developing RECHARGEABLE Zinc-air batteries
  • Duracell technical bulletin (suppliers of zinc-air hearing aid batteries)
  • Overview of batteries
  • Electric Vehicle division

External Links

  • My Old Camera — Source for Wein Cell Zinc-air photo batteries


 

 


 


Retrieved from "http://en.wikipedia.org/wiki/Zinc-air_battery"
 

 


 

 
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