[zinekeller]

Good point. The Dreamliner has such problems in its Li-ion batteries to the point that the weight savings due to composite construction was subsequently nullified by metal retrofits to contain battery fires (https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_...). Additionally, IATA has put strict limits on Li-ion cargo due to Lithium being too reactive, so any plane with Lithium batteries must consider that.

[mastax]

It negated the benefits of the lighter batteries, not the benefit of the composite airframe.