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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
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  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/Molten_salt_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 

Molten salt battery

From Wikipedia, the free encyclopedia

 

Molten salt batteries are a class of primary cell and secondary cell high temperature electric battery that use molten salts as an electrolyte. They offer both a higher energy density through the proper selection of reactant pairs as well as a higher power density by means of a high conductivity molten salt electrolyte. They are used in services where high energy density and high power density are required. These features make rechargeable molten salt batteries a promising technology for powering electric vehicles. Operating temperatures of 400 to 700°C however bring problems of thermal management and safety and places more stringent requirements on the rest of the battery components.

Primary cells

Referred to as thermal batteries the electrolyte is solid and inactive at normal ambient temperatures. In these batteries the electrolyte is usually stored separately from the electrodes which also remain in a dry inactive state. The battery is only activated when it is actually needed by introducing the electrolyte into the active cell area and elevated to high temperatures by the application of heat from an external source, generally a pyrotechnic charge. This is achieved by burning electrically fired pellets of gas-less thermite. Activation takes between 0.2 second and a few seconds, depending on the size of the stack, and is initiated by a percussive primer. Other methods use an electric heater, or a pyroelectric material, like iron powder potassium perchlorate/zirconium barium chromate placed between the cells in the battery to obtain the required temperature.

This property of unactivated storage has the double benefit of avoiding deterioration of the active materials during storage and at the same time it eliminates the loss of capacity due to self discharge until the battery is called into use. They can thus be stored indefinitely yet provide full power in an instant when it is required. Activated they provide a high burst of power for a short period (A few tens of seconds to 20 minutes or more.) with power output ranges from a few watts to several kilowatts. Older batteries used calcium or magnesium anodes, but lithium anodes are now common. Typical chemistry is lithium iron disulphide. The electrolyte is normally a eutectic mixture of lithium and potassium chlorides.

These batteries are used almost exclusively for military applications.

Secondary cells

Since the mid 1960s much development work has been undertaken on rechargeable batteries using sodium (Na) for the negative electrodes. Sodium is attractive because of its high reduction potential of -2.71 volts, its low weight, its non toxic nature, its relative abundance and ready availability and its low cost. In order to construct practical batteries the sodium must be used in liquid form. Since the melting point of sodium is 98°C this means that sodium based batteries must operate at high temperatures, typically in excess of 270°C.

Sodium/sulfur and lithium/sulfur batteries comprise two of the more advanced systems of the molten salt batteries. The NaS battery has reached a more advanced developmental stage than its lithium counterpart; it is more attractive since it employs cheap and abundant electrode materials. Thus the first commercial battery produced was the Sodium/Sulphur battery which used liquid sulphur for the positive electrode and a ceramic tube of beta-alumina solid electrolyte (BASE) for the electrolyte. Corrosion of the insulators was found to be a problem in the harsh chemical environment as they gradually became conductive and the self-discharge rate increased. A further problem of dendritic-sodium growth in Na/S batteries led to the development of the zebra battery.

The zebra battery, which operates at 250°C, utilizes molten chloroaluminate, (NaAlCl4) which has a melting point of approximately 160°C, as the electrolyte. The negative electrode is molten sodium. The positive electrode; is nickel in the discharged state and nickel chloride in the charged state. Because nickel and nickel chloride are nearly insoluble in neutral and basic melts, intimate contact is allowed, providing little resistance to charge transfer. Since both NaAlCl4 and Na are liquid at the operating temperature, a sodium-conducting beta-alumina ceramic is used to separate the liquid sodium from the molten NaAlCl4. This battery was invented in 1985 by a group led by Dr.Johan Coetzer at the CSIR in Pretoria, South Africa, hence the name zebra battery (for the Zeolite Battery Research Africa Project) has been under development for almost 20 years.The technical name for the battery is Na-NiCl2 battery.

The ZEBRA battery has an attractive specific energy and power (90 Wh/kg and 150 W/kg). The liquid electrolyte freezes at 157 C, and the normal operating temperature range is 270–350 C. The β-alumina solid electrolyte that has been developed for this system is very stable, both to sodium metal and the sodium chloroaluminate. Lifetimes of over 1500 cycles and five years have been demonstrated with full-sized batteries, and over 3000 cycles and eight years with 10- and 20-cell modules. Vehicles powered by ZEBRA batteries have covered more than 2 million km.

When not in use, zebra batteries typically require being left under charge, in order to be ready for use when needed. If shut down, a reheating process must be initiated that may require up to two days to restore the battery pack to the desired temperature, and full charge. This reheating time will however vary depending on the state-of-charge of the batteries at the time of their shut down, battery-pack temperature, and power available for reheating. After a full shut down of the battery pack, three to four days usually elapse before a fully-charged battery pack loses all of its significant heat.

See also

  • Molten-carbonate fuel cell

References

  • Additional information & application
  • Thermal Battery Design
  • The ZEBRA concept
  • Thermal Batteries
Retrieved from "http://en.wikipedia.org/wiki/Molten_salt_battery"

 


 

 
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