> I didn't bother to give sources because everything is pretty trivial to find If it was then I wouldn't be asking :) Best I was able to find was a chart (ost

> I didn't bother to give sources because everything is pretty trivial to find If it was then I wouldn't be asking :) Best I was able to find was a chart (ostensibly from NASA) comparing different battery technologies, which is probably where the 3× claim originated, but doesn't say much about improvements over time (only by technology): https://www.epectec.com/batteries/cell-comparison.html https://www.epectec.com/batteries/cell-comparison.html To your point, though, it does indicate that lithium-ion specifically hasn't had such a 3× jump (but it does represent such a jump relative to older technologies like lead-acid or nickel-cadmium). > you can Google "tesla 2170 bench test" or "Samsung INR21700-50E bench test" for details of the best cells today That doesn't really say much about historical trends, but good to know. > "history of 18650" to see that the format is nearly 30 years old Is that relevant? AAs are even older than that, and yet seem to have improved quite a bit. > and "(your favorite 2010 phone) BOM" for some example price data. (as an example: galaxy s4, $5 and 10Wh.) That does line up with https://www.androidauthority.com/galaxy-s4-bill-of-materials-175146/ https://www.androidauthority.com/galaxy-s4-bill-of-materials... (which cites $5.60 for 2600mAh, or $4.90 for 2100mAh). Meanwhile, the Galaxy S9+ lists $4.90 for 3500mAh: https://technology.informa.com/601100/galaxy-s9-materials-cost-43-more-than-previous-versions-ihs-markit-teardown-shows https://technology.informa.com/601100/galaxy-s9-materials-co... Neither of these really say much for the mass, though, so it's hard to get a clear picture on energy density from this. > Nobody wants to read a complex multifaceted failure analysis I mean, I would, but I'm well aware of my insanity.