I guess NiCd is still legal here in the US, well, that or the solar light manufacturers in China just sell them anyway hoping nobody opens the lights to check. Here's one of the NiCd AAAs I got from another light with a bigger battery:

In AAA form they're still surprisingly useful (I bought a USB NiCd/NiMH charger on Ebay for a few bucks awhile back) for powering random devices without wasting disposable cells.