Possible Solutions

Magnetodynamic Coupling

Status: fail

Reason: It would require a motor inside spining wich would not be able to get fast enough to efficeintly charge a phone, it would be loud, and it could become unreliable when the motor goes bad.

Capacitive Coupling

Status: fail

Reason: It would have to be very long to get it to be efficeint enough to charge a phone. It would be impractical to charge a phone with something that big or have it be that inefficient.

Inductive Coupling

Status: pass

Reason: It can be small, cheap, quiet, reliable, and overall convenient. The only downside to this solution is it isnt 100% efficient but it is the most efficient option from the three.