A while back BC ( before Covid) I watched a video ( you tube or someone's channel elsewhere on tv) where a US professor was developing solid state batteries. He did a demo of making one with his solid state " electrolyte" sandwiched between foil layers. A 3 layer structure, quite thin.He built a simple circuit running a bulb with crocodile clips and bulb holder. He then started cutting the " battery" up using scissors. No bad effects. He cut it down to a very small size and the bulb stayed lit. It looked quite good.
Having seen videos of people filming deliberately damaging Li batteries and the resultant uncontrollable reaction this development looked the way to go.
If I can find it I'll post a link.
