i've been taught that batteries are toxic and shouldn't be mixed in with regular trash

what should i do with my used batteries in Kunming?

Green Kunming collects used batteries, which we take to a special battery collection point downtown. Feel free to bring your batteries by, here's how to find us:

www.greenkunming.com/en/contact/

Last I checked, there was a little shop called Oasis Gift Shop that also accepts batteries for recylcing. It's around the corner from Paul's Shop near Yunnan University. The phone number is 5358677.