So this got me curious and I started to look at something a bit more concrete: the history of 18650 cell capacity. Currently the highest capacity 18650 that's w

So this got me curious and I started to look at something a bit more concrete: the history of 18650 cell capacity. Currently the highest capacity 18650 that's widely available is 3500 mAh. The first such cell I found is the LG MJ1 which dates back to 2014: https://cdn.shopify.com/s/files/1/0481/9678/0183/files/lg_mj1_data_sheet.pdf https://cdn.shopify.com/s/files/1/0481/9678/0183/files/lg_mj... I also found a 3200 mAh model from 2012: https://cdn.shopify.com/s/files/1/0481/9678/0183/files/panasonic_18650b_data_sheet.pdf https://cdn.shopify.com/s/files/1/0481/9678/0183/files/panas... That's a fair bit less than a 3x improvement over 10 years. Now of course this is a rather crude and unscientific measurement. It's also effectively measuring energy density by volume rather than weight, but volume is more often the limiting factor for Li-ion batteries (e.g. smartphones and EVs are volume limited). Still, I think this shows why people are skeptical about claimed massive improvements in battery tech: it's hard to find clear evidence of it in actual products people can buy.