You could always buy one of these and have it inside your favourite case I don't have the need to charge in the car, so I have purchased the Toyota leather console tray to cover it up.
I don't like having that plug either in the phone or dangling out during all of the times that I'm not using the wireless charger in the car. For me it's easier just to switch cases every once in awhile.
I've posted in the few other Qi threads, I've been using this system that I backed from kickstarter Wireless Charging Case iPhone 6/6S It's one of the few cases that supposedly supports 1amp wireless charging, most of the ones thin insert ones only do .7 or .8 amps meaning if you use GPS or battery intensive tasks it can still charge rather than lose power gradually. QI Receiver for an iPhone that works in a Prius? I have purchased the iphone 7 plus case to see if the passthrough power ability works Wireless Charging Case iPhone 7 Plus
I bought iPhone 7 Plus Wireless Charging Receiver, Nillkin Magic Tag Qi at Amazon for my 7 plus. I do not always charge it while driving and I do not have a case. I leave the Qi charging tag in the Qi tray of my Prius until needed. When the phone is low on charge I simply take a few seconds to plug the Qi into the lightning port and place the phone in the Qi charging tray. When I arrive at my destination I simply pick up the phone and unplug the Qi from the lightning port then deposit the Qi tag in the Qi charger and I am ready to go. This also has an adhesive strip if you wanted to attach the tag permanently and use it with whatever case you want. I chose not to.
Sometimes I think we do these chicken dance to use the Qi charger instead of simple USB or lightning cable from a socket. That is far, far simpler IMHO.
Just picked up my 2017 Prius 3 touring which has the Wifi charging system, however, my iPhone 7+ does not have that Wifi charging capacity. Bought a case from Best Buy, to adopt the iPhone to Wifi charging. Major problem was the "new" overall length was such that the case would not lay flat, hence the Wifi charging could not work. Plus, the adapter plug on the "new case" would not accept the Apple mini plug. The next thought..if I may state, it would be nice if the electronic key module had that wifi charging feature built in..So one could lay the electronic key in the tray to charge while driving, etc.
It isn't a rechargeable battery, I think a CR2032. I don't expect the battery in my electronic key to need charging. My last 2 cars, kept for 3 yrs and 4½yrs were still on the original batteries. They're cheap anyway.