A few months ago, I frankly had no idea what a lithium manganese rich (LMR) battery even was. Now, the president of General Motors is saying this new chemistry could unlock the midsize electric trucks that have been a gaping hole in the electric market for years. On this week's Plugged-In Podcast, we asked GM President Mark Reuss: Just how big a deal are these newfangled LMR batteries you're working on?