I am only a simple seaman but I know two things that are relevant here:
1. As I said in 7608, Halon does not suppress a lithium ion battery runaway.
2. The biggest cause of loss of life amongst merchant seamen is entry into enclosed spaces with unsafe atmospheres: we are taught that if the atmosphere in the space, always tested before entry, is anything other than 20.9% O2 we do not enter the space, because if the O2 content is below normal, it has been replaced with something else.