Recharable batteries

I have 4 AA batteries (energizer) that are hooked up to my robot (they give 5.3 volts full charge) If I wanted to charge these in my robot could I add a diode to the batteries and plug in USB power to Arduino and charge batteries? would they charge?

would they charge?

No, with a diode you loose 0.7V so that you only have 4.3V and that is not enough to charge your battery.