Is it possible to buy an iphone 5s battery online?

The iphone 5 connector is slightly bigger than the iphone 5s, I was looking online if anyone sold iphone 5s battery replacements but had no luck at all. Any suggestions?

If your battery needs replacing, go to the Apple Store, your phone should still be under warranty.

I think so. Search on ebay or somewhere. You can find online.

You just got the phone. We better for you to have Apple do it since it is still under warranty. And you get a first party battery instead of one of those weird third-party batteries which tend to be of poor quality.