I really like your observation of a "lithium battery age". But people tend to greatly overestimate how much lithium batteries improve: we remember a class of b

I really like your observation of a "lithium battery age". But people tend to greatly overestimate how much lithium batteries improve: we remember a class of battery powered devices that ran on NiMH, then at some point LiIon became cheap enough for that use case so that the next generation that we got was so much better. We then extrapolated a fantasy battery improvement speed from that one-time jump and this mistake is rarely corrected. Instead it was supported by the next device class that got absorbed by the ever shrinking lithium price threshold. This process is now about finished, very few NiMH applications left to get "lithiumized". But the fantasy also supported, one a lower intensity but enough to impede corrections, by how the actual actual progress within lithium batteries (not quite as big as we wish, outside of price at least) gets complemented by devices becoming more efficient (think LED flashlights) and devices dedicating an increasing fraction of their mass/volume to the battery (smartphones, laptops, also cars if you compare to pre-Tesla electrics)