You can be clear about that, but in all honesty, once an animal leaves your possession, there's really not much you can do about it. It's no longer your animal. I've found it's best to not ask questions after I sold a good little horse to a friend, only to find out later he'd not been cared for and they had to put him down.(She seemed like she really wanted him and would give him a good home - I'd visited the place, liked what I saw, but I guess things got ugly in her marriage and everything else suffered, too.) So from now on, I have a don't ask policy. Chickens, honestly, it's up to the person taking them. Once they leave, they are no longer my concern.Most of the previous posts bring up a very good point. Ask yourself if the main reason you got the chickens was to have a few eggs or was it to give them a good home? I know it was probably both for you, but what really mattered to you most?
I'm not familiar with that breed, but Naser said they lay fast and hard early on. I doubt they will NEVER lay an egg again, but what to expect realistically, I'm not sure. An egg or two a week?
Have you ever received ANY eggs from them? How long have you had the birds?
If you you've had them less than a year, they might need more time to recover. I'm not sure how bad the battery conditions were. If I were you, I certainly wouldn't do anything to try to force them to lay, such as adding extra light in the fall/winter or feeding lots of cayenne pepper. Just let them be and perhaps they will lay for you some day.
If you're okay with the possibility that you may never get eggs (and it sounds like you are), your chickens sound like they have a good life.
If you're not okay with it, you might consider either 1) illegally adding another couple (non-battery) chickens for eggs or 2) re-homing two of your current flock and replacing them with new chickens. If you do #2, be sure to be honest with whomever takes them that there is a good chance they will never lay eggs. And if you don't want them on someone's dinner table, be clear about that.