With Android version 9.0.1 of Sonos controller multiple pleople reported battery drain issues, I got that problem too. It's really inconvenient to find that issue remain usolved in version 9.1. I had to uninstall Sonos controller from my cell phone. Even when the Sonos controller is not in use, I'm at work, the Sonos controller drains the battery really fast. It's a HTC one A9 with Android 7.0.
Unfortunately I'm not able to use the sonos cotroller in my cell phone. I've found multiple people reporting the same issue, it's surprising the issue is not fixed yet.