We have spent years being told that electric aviation is just around the corner. The trouble is that the corner keeps moving. Batteries are heavy, aeroplanes are fussy, and physics remains annoyingly difficult to negotiate with.

Now Amprius Technologies has produced something rather interesting: a 500 Wh/kg silicon-anode battery that could make electric aircraft considerably more useful.

The clever bit isn’t simply the number. Amprius already makes 500 Wh/kg cells. The difference is that this new SiCore version can be produced by contract manufacturers using existing lithium-ion manufacturing equipment. In other words, this isn’t just laboratory wizardry — it has a route towards being built in serious quantities.

The battery is designed around a continuous 1C discharge, making it particularly attractive for endurance machines such as fixed-wing drones and high-altitude pseudo-satellites. And if you think drones are merely flying cameras, think again.

Amprius already supplies batteries to Aalto, whose solar-powered Zephyr aircraft reportedly stayed airborne for 67 daysin 2025. More energy density means potentially more endurance, more payload or simply more time doing whatever mysterious things these aircraft are doing several miles above our heads.

Business is taking off too. Second-quarter revenue hit $34 million, more than double the previous year’s figure, while one drone manufacturer has now committed another $35 million after an earlier $15 million order.

The catch? Production still relies heavily on China and South Korea. But if Amprius cracks the manufacturing problem, the future of electric flight might have just become considerably less ridiculous.