Apple introduced the addition of the glass back on the iPhone 8, iPhone 8 Plus, and the iPhone X. While this switch doesn’t increase the durability of the phone, it does allow wireless charging. Currently, the iPhone 8 and iPhone X support a charging speed of 5W, which is the slowest supported Qi charging speed. To put this into perspective, a 5W wireless charger will take about two hours and 30 minutes.
According to MacRumors, iOS 11.2 beta is rolling out with faster wireless charging speeds at 7.5 watts using compatible Qi accessories. This will allow the iPhone 8 and iPhone X to take full advantage of Apple’s approved wireless chargers: Belkin BOOST UP and mophie wireless charging base. The iOS update might be in preparation of Apple’s AirPower charging mat coming sometime in 2018. The AirPower charging mat has a larger footprint, which allows charging of multiple devices at the same time. There is speculation at the official price of the AirPower charging mat, but people are expecting it to fall in the $149-200 range.
Wireless charging is not the fastest way to charge your iPhone. If you care about charging speed, try using the 12W charger that comes with iPads or a USB-C to Lightning cable.