Paleblue

Paleblue makes rechargeable lithium-ion AA batteries that charge over USB-C, with the battery management circuitry built into each cell. The US throws away about ten million single-use batteries a day, roughly 95% of which go to landfills and incinerators, and everyone who buys them knows it and buys them anyway, because the rechargeable alternatives have been mediocre for forty years.

Nickel-metal hydride rechargeables self-discharge in a drawer, need a dedicated charger, and deliver a lower voltage that some devices reject. So people give up and go back to alkaline. Lithium-ion fixes the chemistry but only works in this form factor if each cell carries its own management, which is the engineering. One cell replacing a thousand disposables is a very large multiple applied to a very ordinary object.