Can you get electricity from your mobile phone
In case of Android it is possible in OTG mode.

Your phone becomes Master/Host and supplies energy to a Slave device (a mouse, a storage device, etc..):


  USB OTG defines two roles for devices: OTG A-device and OTG B-device, specifying which side supplies power to the link, and which initially is the host. The OTG A-device is a power supplier, and an OTG B-device is a power consumer. In the default link configuration, the A-device acts as a USB host with the B-device acting as a USB peripheral.


You have to connect the ID pin of the connector to Ground:


  The device with a mini-A plug inserted became an OTG A-device, and the device with a mini-B plug inserted became a B-device (see above). The type of plug inserted was detected by the state of the ID pin (the mini-A plug's ID pin was grounded, while the mini-B plug's was floating).




In case of iOS it is technically possible because there are accessories that use power from the plug, but the process of fabricating a compatible device has many more hassles, such as applying to be a developer, etc..