That's not a useful comparison. The power of the explosion at Chernobyl, while deadly to the one person immediately next to it, was not the problem that made Chernobyl the catastrophe that it was. That was the radionuclide contamination that it spread and the remaining latent power in the fuel that, if released uncontrollably, would have spread it even further.
A grid scale lithium ion battery, even completely burned up and vaporized into the atmosphere, is not dangerous in a comparable way.
not to mention that battery fires don't release all of their stored energy at once, unlike explosives. Granted, they might burn uncontrollably for a long time, and difficult to extinguish.