Technology has never failed to surprise a common man. Its strange to hear that but now you can charge your mobile in air while walking in room and placing it some where randomly in room. Xiaomi has invented this technology.
There will be a medium or tower in a room that will provide a charging signals to your mobile phone it just works like a sim network working in your phone but for this technology there will be antennas of size 144 mol in your room ceiling which will convert signals of tower or base station in your room to energy that will charge your phone.
Your phone will get charging speed of 5 watt and this base station/ tower will provide charging signals 10 meters range.
This technology is not really available in market right now but its expected that it will be available till next year.