Battery life is still the biggest obstacle to mobile products. In current market, there is hardly any smart phone being used under high-intensity for a whole day, so we need to charge it frequently. However, it is such annoying to carry the data cable and charger anytime and anywhere. Is there any solution to get rid of this trouble? Wireless charging is undisputed to be the most potential choice. However, wireless charging technology has invented for so many years and why it is not yet universal? what are the main obstacles to its development?