Want to make a battery? All you need are several lemons, other fruits, or fruit juices, two different kinds of metal, and some pieces of wire for connecting everything together. Once you have those items, you need only a little knowledge of electrochemistry and you’ll be ready to go.

How does a fruit battery produce electrical energy? The fruit itself is a container for a solution of electrolyte. As you may know most fruit juice is acidic. The hydrogen ions provide the conduction of charge through a lemon battery. Two dissimilar metal strips are electrodes at which an oxidation reaction and a reduction reaction take place to provide the batteries power source.

Two different chemical reactions take place at each of the metal strip electrodes. The electrode with the metal that is more easily oxidized becomes the anode, the electrode at which the oxidation reaction occurs. The second electrode becomes the cathode, and the reduction reaction proceeds at its surface. When these two reactions occur together, in the same cell, they combine to produce a spontaneous redox reaction. This spontaneous reaction generates the cell voltage of a battery by producing a different electrical potential and each electrode.

Easily Oxidized / Oxidation Potential (V)
/ Li / 3.04
K / 2.92
Ca / 2.87
Na / 2.71
Mg / 2.37
Al / 1.66
Mn / 1.18
Zn / 0.76
Cr / 0.74
Fe / 0.44
Ni / 0.25
Sn / 0.14
Pb / 0.13
Cu / -0.16
Ag / -0.78
Hg / -0.80
Pt / -1.20
Au / -1.50
Not Easily Oxidized
Fruit (electrolyte) / Anode
(Red) / Cathode (Black) / Prediction /

Voltage

Lemon / Aluminum / Zinc
Lemon / Aluminum / Nickel
Lemon / Aluminum / Copper
Lemon / Zinc / Aluminum
Lemon / Zinc / Nickel
Lemon / Zinc / Copper
Lemon / Nickel / Aluminum
Lemon / Nickel / Zinc
Lemon / Nickel / Copper
Lemon / Copper / Aluminum
Lemon / Copper / Zinc
Lemon / Copper / Nickel
Orange / Aluminum / Zinc
Orange / Aluminum / Nickel
Orange / Aluminum / Copper
Orange / Zinc / Aluminum
Orange / Zinc / Nickel
Orange / Zinc / Copper
Orange / Nickel / Aluminum
Orange / Nickel / Zinc
Orange / Nickel / Copper
Orange / Copper / Aluminum
Orange / Copper / Zinc
Orange / Copper / Nickel
Tomato / Aluminum / Zinc
Tomato / Aluminum / Nickel
Tomato / Aluminum / Copper
Tomato / Zinc / Aluminum
Tomato / Zinc / Nickel
Tomato / Zinc / Copper
Tomato / Nickel / Aluminum
Tomato / Nickel / Zinc
Tomato / Nickel / Copper
Tomato / Copper / Aluminum
Tomato / Copper / Zinc
Tomato / Copper / Nickel

Follow Up Questions:

1. Which batteries produced the most electricity?

2. Knowing that we cannot make or destroy energy, where does the electrical energy come from?

3. Based on what you learned in class today design a battery that would be more effective then those that we tried in class today.