Stir together the cabbage, potatoes, and fennel in a 5- to 6-quart slow cooker coated with cooking spray. Whisk together the wine, vinegar, sugar, and coriander in a small bowl. Stir the wine mixture into the cabbage mixture. Add the bay leaves to the slow cooker, and submerge in the mixture. Cover and cook on LOW until the cabbage is tender, 4 to 5 hours. Discard the bay leaves. Stir in the butter, salt, and pepper. Sprinkle the top with the thyme leaves.