Why don't diode as a battery?

Why because it is not a source as Li-ion battery. If we want to measure the voltage(build in voltage) with in the diode we have to use the external source. We can''t directly measure the voltage present in the diode with the multimeter. Why because if we use the multimeter in the metallic contact the two potentials will be cancel out. More precisely diode is neutral.

Friend Can''t get ur question Is it why diode can''t be used as a battery or Why don''t diode is used as a battery? Well the answer for the both is Diode is a Current flow rectifier a device use to Control the flow of Current Using diodes we make those logic gate AND ,, OR ,, NOR(Cheapest universal gate). Battery Creates a P.D across the circuit where it is placed.