And for people who believe that, I'm going to say that there are some really smart people at Samsung and Apple and other high-end electronics manufacturers that work in huge volumes, and they couldn't figure it out. Are you smarter than they are? Do you know your supply chain better than they do?
What are you saying they didn't/can't figure out? Both companies still use lithium batteries in all their products. Both have good safety records. Ergo; they have "figured it out". Neither is going to go back to the obsolete ni-mh chemistry. They'll change when the water based graphene cells start to get mass produced, I'm sure.
The problem isn't the lithium battery. Heck, it's safer than gasoline or diesel fuel or uranium as an energy source.
As with anything, there is room for improvement. Lithium batteries are often used with no proper casing (as is the case with cell phone batteries). They rely on the device that the cells are installed into for physical protection. 18650 cells do have a minimal casing; although it would be nice if cells could be made with a stronger physical casing.
Personally, I think you're wasting your time trying to move people back to a dead battery technology. Nobody is going to go out and buy an iphone 11 if it only has 1hr battery life or if it is the size of a 1980's car phone. Most people aren't going to go back to dive lights with butt-mount battery canisters and cables. It would be better to spend your time working towards a new technology as I mentioned above.
As for safety on a boat with lithium goes... I think
@Wookie got it right. No charging batteries where you sleep. Deal with suspect cells appropriately. Want to take it a step further? Use a proper
bat-safe box for charging cells on a boat. I have one for charging cells in my house. If one of them catches fire, the box will contain the fire and filter out any dangerous fumes that are discharged.
I think it would be a good move for the USCG or whoever makes 'da rules' to create a rule about where batteries can be charged and stored while on a boat. That should include devices with integrated batteries such as a laptop or cell phone. Maybe it should even include the boat's onboard battery bank location. Of course that won't help the other 90% of the world that isn't concerned with USCG regulations...
I get the cells from IMR Batteries. I use a good charger. Generally I charge batteries during the day. In most cases I put the charger in a large cast iron frying pan in the kitchen, which I believe is sufficient to limit any fire that might occur to the batteries and the charger. I'm still thinking through whether that's good enough and whether I want to keep them.
Get a bat-safe box. They're not super expensive and will be far safer than that frying pan.