I'm a little surprised by that energy density chart. Who's selling batteries that carry 500 Wh/kg? Those are research prototype numbers; I think that Amprius an

I'm a little surprised by that energy density chart. Who's selling batteries that carry 500 Wh/kg? Those are research prototype numbers; I think that Amprius and the gamma-sulfur people have hit (or passed) that mark. But cars and cellphones have been using the Ni-Mn-Al-Co oxide family of cathodes for a decade. The recent large-scale development has been bringing on LiFePO4 which actually accepts a lower density in exchange for lower cost and longer life. That doesn't discredit the predictions, but I don't think that the connection they're trying to draw between energy density and market demand really holds water. The development of higher density batteries is good for certain applications like that ground-effect electric seaplane, but it isn't necessary for cars or grid storage, where the first case is mostly viable already and the second is concerned with the cost outlook and the self-discharge rate.