How about a phone that uses power from a nearby cell tower?  Sounds like a great idea, but you have to make calls.  Might not work with texting.  http://fortune.com/2017/07/09/battery-free-cell-phone/ 


BERLIN, GERMANY - SEPTEMBER 16:  A visitor tries out an Apple iPhone 7 on the first day of sales of the new phone at the Berlin Apple store on September 16, 2016 in Berlin, Germany. The new phone comes in two sizes, one with a 4.7 inch display, the other