Tesla may have batteries with as much as 50% higher capacity in just a few years, if a tweet by Elon Musk is correct.

Tesla is widely considered to have significant lead in battery tech, as well as its electronics tech. This has given the automaker a roughly $50 per kilowatt hour (kWh) advantage over rivals. According to Elon Musk, however, that advantage may soon be even bigger.

Responding to a user asking about Tesla’s rumored electric airplane, Musk indicated volume production of 400 Wh/kg batteries is just a few years away.

If Tesla is able to achieve what Musk is describing, this would open the door to a number of possibilities, including that rumored plane. It would also put significant pressure on rivals, many of whom are already several years behind Tesla.