There will always be a realy fucking bad failure mode attached to any energy dense storage medium. This is basic physics. The diffrence between a roaring fire in the wood stove, your car engine, an ultra high tech rocket motor and a bomb, is only the speed of the "flame front" A battery has the same issues, in that the higher the energy density and the greater the expected rate of energy transfer, the greater the chance of finding a way to detonate all the energy at once, which is actualy possible ,with a wood stove, if things go exactly wrong.Exceptionaly large explosions have happened with nothing more than dust, or flour. 4 things, you can pick 3. fast, powerfull, cheap, safe.