There is a cell phone parking lot?

Yeas they have a cell phone lot. https://www.flychicago.com/ohare/tofrom/dropoff/Pages/default.aspx

I think so, but it's been a while since I drove to the airport. I think there might also be free parking over at that mall near the airport (next to the Crowne Plaza) that's about 2 miles and there will be other facilities... In case you have to wait an extended time.