Why can diodes not be used instead of batteries?

Why can diodes not be used instead of batteries as a source of energy. Bothe batteries and diodes have current flow in one direction and diodes have potential voltages of up to 1.4V and are cheaper than batteries - so they seem like better choice. Electron flow in a single direction provides a source of energy.

Do batteries & diodes contain stored energy?

As has already been stated plenty well enough, batteries contain stored energy which they can release electrically to a circuit, diodes don't. I think this is the correct answer for the OP.

Are diodes an energy source?

Diodes are not an energy source. They modify how energy may flow. Their function is to allow current or electrons or charge to flow in one direction in a circuit much more readily than in the other direction. A good analogy is to think of them as a non-return valve of one-way-valve in a water flow system.

What is the difference between a battery and a diode?

They are confused BUT the question makes less sense when edited that it did originally. Consider the direction of current flow relative to the drop across the device; in a battery, the current is out of the positive terminal, whereas with a diode, the current is into the positive terminal.

How does a diode affect a battery?

This tells you that the battery produces power, whereas the diode consumes power. Which holds up to the point where you can somehow cause charge dissociation in the diode's depletion region with an external energy source. With typical diodes, this is nigh on impossible.

Why are diodes not a power source?

As a couple of others have already pointed out, the reason is that diodes (except for some special cases where there's an external source of energy from light) don't work as a power source in a circuit, whereas batteries do. I'll expand on how you can see that is true. Power is the product of current and voltage.