Battery external connection device for use with mobile phone and flip cover having the device

A flip cover applying to a mobile phone, having a battery external connection device, and comprising a front unit and a rear unit connected to the front unit, the flip cover being characterized by:

• an ultra-thin rechargeable battery;
• the front unit having therein a sandwich space for accommodating and thereby storing the ultra-thin rechargeable battery;
• the rear unit having thereon a battery external connection device and functioning as a back cover of a mobile phone to thereby substitute for an original back cover of the mobile phone;
• and
• the battery external connection device comprising a first electrical connection terminal and a second electrical connection terminal, wherein the first electrical connection terminal and the second electrical connection terminal are electrically connected to a positive pole and a negative pole of the ultra-thin rechargeable battery, respectively.