Qi

Qi is a standard for wireless charging developed by the Wireless Power Consortium. The name Qi is taken from the traditional Chinese word for flow of energy; Qi is frequently translated as "natural energy", "life force", or "energy flow".

A Qi standard, and associated products, is already available for wireless charging of low-power applications (up to 5 Watts), suitable for mobile phones and other devices. A standard for medium-power and high-power applications is under development.

Wireless charging is based on the phenomenon of induction. The technology requires two coils: a transmitter and a receiver. An alternating current is passed through the transmitter coil to generate a varying magnetic field. This in turn induces a current in the receiver coil; this can be used to power a mobile device or charge a battery. In case of wireless charging of small devices, the transmitting coil is put in a flat thick pad. Just put the device on the pad, at home, in your car, at the office, or e.g. in a coffee shop, to get it charged.

Inductive charging is probably best known from the electric toothbrushes. It is also already used in other types of devices such as implanted medical devices, like pacemakers. Qi extends wireless charging to the mobile phone and other small devices.