I remember doing some back of the envelope calculations, and hydrogen fuel cells offer somewhat better volumetric energy density than current batteries do - and

I remember doing some back of the envelope calculations, and hydrogen fuel cells offer somewhat better volumetric energy density than current batteries do - and it's no contest with regards to weight. I'm not super familiar with cargo aviation, so I'm not sure how often are aircraft weight limited, as opposed to volume limited. In the former case, the low density of hydrogen would probably be less of an issue.