Hobovision, 10 months ago

If we're talking approaching fundamental limits, Hydrogen fuel cell is not a great comparison. A high pressure tank can only get so light, even with linerless ultra high strength carbon fiber pressure vessels, the mass of the vessel is maybe 6-10x the mass of the hydrogen it carries. To increase specific energy there you need to go to cryogenics which is a whole technology leap and has its own set of challenges.

Battery tech has been improving more than you have seen, clearly. Since '08, lithium batteries have increased energy density by 8x (https://www.energy.gov/eere/vehicles/articles/fotw-1234-april-18-2022-volumetric-energy-density-lithium-ion-batteries). The best LiPo batteries are around 0.9MJ/kg right now, but there's no fundamental reason a battery couldn't achieve 9MJ/kg. Lithium-air batteries could theoretically achieve way higher energy density than that even (https://en.m.wikipedia.org/wiki/Lithium%E2%80%93air_battery), and have already been demonstrated in a lab to achieve more than 5x what current commercial automotive batteries are doing.