As battery tech improves, by definition we are going to reach ever increasing energy densities, ideally on the order of magnitde of hydrocarbons'. Moreover, pe

As battery tech improves, by definition we are going to reach ever increasing energy densities, ideally on the order of magnitde of hydrocarbons'. Moreover, people will want for devices to charge fast. This implies a lot of waste heath, which negatively impacts energy efficiency and requires smart electronics to keep temperatures under control (I suspect this second aspect is what failed in this case). However, once we get to high densities, we'll have to consider safety seriously: who would want to sleep close to all that energy stored in a small space, with zero activation energy to protect from a runaway?