A battery diagram shows the positive and negative electrode, according to ExplainThatStuff.com. It may also show a wider circuit connected to the battery.
Batteries contain one or more cells, the working chemical units inside a battery. A cell has three parts: a positive electrode, a negative electrode and a separating liquid or solid known as an electrolyte. The positive and negative electrodes may also be labeled as the cathode and the anode, respectively. These are the basic constituent parts of a cell which will appear on a diagram. If a battery has only one cell, the diagram may only show those three parts.
An example diagram on Explain-That-Stuff.com shows a one-cell battery as described above. It also shows a circuit connected to that battery and the flow of current through it. This is shown as ions and electrons. These are generated when the circuit is switched on and chemical reactions occur. Negative electrons are generated at the negative electrode and wish to travel to the positive electrode. However, the electrolyte insulates against this happening, which forces the electrodes to flow around the circuit, generating electricity. This is shown in the example diagram through a lamp lighting up, although this would depend on the constituent parts shown in the circuit diagram.