Daniell cell
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The Daniell cell (var. sp. Daniel cell), also called the gravity cell or crowfoot cell was invented by John Frederic Daniell, who was a British chemist and meteorologist. The Daniell cell was a great improvement over the voltaic cell used in the early days of battery development.
It is an electrochemical cell that uses zinc (ZnSO4) and copper (CuSO4). It was invented in 1836 by John F. Daniel of England and is somewhat safer than the Volta cell. The Daniel cell's theoretical voltage is 1.1 volts and the chemical reaction is:
The other common arrangement known as the gravity cell or crowfoot cell dispensed with the porous barrier and used stratified layers of zinc sulphate and copper sulphate solutions relying on the difference in specific gravity to keep them from mixing. The electrodes shaped like "crow's feet" sat in their respective zones. This arrangement was less costly for large mulicell batteries but could not be moved and was vulnerable to loss of integrity if too much electric current was drawn, which would cause the layers to mix.
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The Daniell cell proper consists of a central zinc cathode dipping into a porous pot containing zinc sulphate solution. The porous pot is, in turn, immersed in a solution of copper sulphate contained in a copper can, which acts as the cell's anode. The use of a porous barrier prevents depolarization (the covering of the anode with small bubbles of hydrogen gas) and allows the cell to generate a continuous current of electricity.External links
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