Haven't used it, but it's mentioned on the CDG airport website
http://www.parisaeroport.fr/en/passe...uggage-storage
Air France says there are lockers near the RER station
http://www.airfrance.us/US/en/common...le-airport.htm
But if you're getting a hotel room, use that. If you plan to roam all night (which sounds unpleasant to me) then it looks like you could store it at the airport.