It can. Technology exists that allows an electric bike to recharge its own battery through braking: when you use the brakes, a brake sensor triggers the motor to kick into ‘reverse mode’ and use the energy of the bicycle’s forward motion to charge the battery (instead of dissipating this energy as heat through the brakes). This technology is called regenerative braking. It is common on electric cars, but less common on electric bicycles.
While it is possible and provides an effective form of engine braking it does not give a very good return on power. For this reason the additional complexity and weight of a regenerative system vs the return is often negligible.
Sometimes people ask whether our electric bikes will recharge while pedaling. Although it is conceivable that this could be done, because of the low 10% return on input, you would need to pedal 10km to give 1km charge. For this reason all our electric bikes simply plug into the wall to charge. A typical charge takes around 4 hours and costs around 16c.
You can read more about charging and battery capacity in our other FAQ's