Running 7V motors with 2x 3.7v batteries
Battery voltages add in series, so two 3.7V batteries should give you 7.4V, which should work.

You are also limited by the current your batteries can supply. With them in series, two doesn't change the current they can supply, so you can get 1450mA. You have four motors that will need to share this current, so each motor can have up to 362.5mA, if the batteries are powering only the motors. The control electronics will also require some current, and running your batteries at the maximum current will discharge them quickly.

Is this enough? How heavy is your quadcopter? What does the motor datasheet say? The quadcopter you are describing, with an Arduino, and an Android phone, sounds pretty heavy. Without more information it's impossible to know for sure, but I'm guessing you will need bigger batteries. There are plenty of batteries designed for remote control aeroplanes and helicopters. I'd investigate those.