I want to disconnect the hard-wired smoke detectors in my home and use battery operated detectors.

Do not do that!

Why would you want to take a step backwards in safety?

Is this related to your other question? https://www.askmehelpdesk.com/home-safety-security/how-remove-home-alarm-system-installed-adt-782554.html

Does your smoke alarm have a battery backup? That would be the ideal set up. Your local fire department can inform you better but adding a battery smoke alarm to your existing home wired ones is a much better option, if you have no battery back up as in older homes hard wired detectors.

Augmenting your present smoke detectors is the safer way to go for sure, and the less expensive. The older detectors are useless during a power outage. That means you may need an electrician and that's who you consult. Live wires going through your house and connected to nothing are as much a hazard for fire as a grease fire, and battery based detectors have to be maintained or are as useless as hardwire ones during an outage.

You decide, based on the facts, and safety first. I prefer the hard wired ones with battery back up for that reason. An extra layer of protection.

Battery is not the way to go. All newer houses are hard wired, all tied together with battery backup for a good reason-people don't replace batteries. Why do you want to replace?