Battery History

The first battery was created by Alessandro Volta in 1800. To create his battery, he made a stack by alternating layers of zinc, blotting paper soaked in salt water, and silver. This arrangement was known as a voltaic pile. The top and bottom layers of the pile must be different metals. If you attach a wire to the top and bottom of the pile, you can measure a voltage and a current from the pile. The pile can be stacked as high as you like, and each layer will increase the voltage by a fixed amount.

A voltaic pile

In the 1800s, before the invention of the electrical generator (the generator was not invented and perfected until the 1870s), the Daniell cell was extremely common for operating telegraphs and doorbells. The Daniell cell is also known by three other names:

• Crowfoot cell (because of the typical shape of the zinc electrode)
• Gravity cell (because gravity keeps the two sulfates separated)
• Wet cell (because it uses liquids for the electrolytes, as opposed to the modern dry cell)

The Daniell cell is a wet cell consisting of copper and zinc plates and copper and zinc sulfates. To make the Daniell cell, the copper plate is placed at the bottom of a glass jar. Copper sulfate solution is poured over the plate to half-fill the jar. Then a zinc plate is hung in the jar and a zinc sulfate solution is poured very carefully into the jar. Copper sulfate is denser than zinc sulfate, so the zinc sulfate "floats" on top of the copper sulfate. Obviously, this arrangement does not work very well in a flashlight, but it works fine for stationary applications.

The Daniell Cell

If you have access to zinc sulfate and copper sulfate, you can try making your own Daniell cell. In the next section, we'll show you how to do it.