Batteries will become unfit to use after they’ve been in the water. Usually however, a battery won’t leak inside the washing machine thanks to the safety valve - so chances of your textile being affected are minimal.
Panasonic hearing aid batteries, or zinc air batteries, react with air. As soon as you pull off the seal, the battery will be able to release energy. Be sure to let the battery breathe for a few minutes before inserting it into your device.