Assuming you are talking about the ipod touch 5th gen then yes you can replace the battery without replacing the screen. Just pull the screen up, unscrew the metal plate and youll have access to the battery. The battery connections are covered by a black cover. just use a pair of tweezers to pull it off. Then just unsolder the battery and put a new one on! its really a lot easier than it sounds
iPod Touch 5th Generation Teardown
I linked iFixit's guide to the tear down. they tore the cable in the video because "we needed to pull off the soldered battery connections before we could tilt the logic board up to peek underneath." Since you don't need to get behind the board you wont need to worry about that. Again just take off the black cover, 3 solder points and youre all set to go!