As stated elsewhere, even if the electricity to charge was free, batteries won't be economically competitive with HFO/LSMFO in this century.

> But from a cost point of view, sacrificing 20% cargo for an order of magnitude reduction in fuel cost is going to be very tempting.

No, it's not and this shows a profound misunderstanding of the maritime sector. Not to mention, it would be at least 20% of DWT and probably 40% of gross tonnage, and all at the most valuable (lowest/most-stable) part of the hull.

> Or 3 years according to CATL.

CATL make no such claim. They claim that they will be able to show electric ocean-going vessels, which there already are. They make no claims about transoceanic shipping, other than partnering with Maersk, which as stated above, will be for hybrid propulsion to avoid expensive low-sulfur fuels in ECAs and will be charged from HFO at sea.