No other type of battery is going to work very well, imo. Boeing will likely stick with Lithium Ion batteries and get approval to fly. They will probably go with a slightly different type of Lithium Ion battery if they change at all. They will improve the containment system, improve the monitoring system and the charging system, and move on, I think.
You may correct. I understand that they’re currently using the cobalt type which is supposed to be the most reactive and dangerous type.