Larger ships at sea using lithium-ion batteries? Currently, it is not very widespread due to different motivational emphasis between legislation between big ships and small boats. Small boats are legislated more based off of environmental impact and noise generation, so in Europe they have gone pretty much all electric. But big ships, those are regulated based off of safety and reliability, of which is not well proven with lithium-ion batteries, especially for very large battery packs. This is a great article on lithium-ion battery safety in that application and one system design that optimizes such.
20200629/https://www.governmenteuropa.eu/lithium-ion-battery-fire-vessel/88384/
So, keep in mind some numbers on the thermal runaway of lithium-ion batteries. 180 to 220 degrees Celsius for Li-NMC, 270 degrees Celsius for LiFePO4.