The development of a new thin and flexible battery by NEC, based on an organic gel like compound, has great potential for making active RFID tags more viable.
Most RFID tags are passive, and are powered by the radio signal transmitted by the reader. This means that read ranges are very limited and for any appreciable read distances, large aerial are required.
Active RFID tags actually use a power source and can actually transmit a signal without needing power from an external source. One of the advantages with such tags is the far greater read ranges possible.
The other added advantage of the new battery is that it can also use the radio signal from the reader as a means of recharging.