It is alleged that the 7.5w wireless "Fast Charging" for the iPhone is limited to Belkin and Mophie
From 9to5 Mac:
https://9to5mac.com/2017/11/14/iphone-fast-wireless-charging/
From 9to5 Mac:
There is some confusion over exactly what Qi charging accessories can go above the 5w charging speeds. Apple currently sells Qi charging pads from Belkin and Mophie. According to both of those manufacturers, only companies that partner with Apple (like them) will be able to be certified and have their Qi chargers take advantage of the 7.5w power output.
7.5w is an officially supported mode for Qi chargers by the Wireless Power Consortium but it appears Apple is using hardware identifiers to restrict access to accessories that it vets.
https://9to5mac.com/2017/11/14/iphone-fast-wireless-charging/

....since my iPhone is almost constantly on the wireless charging base at my desk while at work, I have more than enough power for when I’m not at work. Heck, I rarely charge it overnight anymore with the exception of the weekend. One of these days, I’m going to drain the battery to about 5% and then put it on my wireless charger just to see how long it takes to charge to capacity.
