All the these systems would probably have batteries (except the fuel cells?) just to store the energy. Having battery technology on this list almost doesn't make sense because batteries don't generate power, as the other technologies do, and batteries may still end up on the devices even if the power is generated on the device.
What the battery category implies is that the power for these small devices is not generated on the device itself but elsewhere. Looks like more engineers are thinking power won't be generated on the device itself at all. I wonder why. Remember those calculators with the light harvesting or solar panels on them. You covered the panel and the calculator turned off.