Two problems I can see: 1. You'd need a hydrogen source. 2. Exactly how much vapor does it release? Water vapor next to sensitive electronics, in your pocket, can be very bad.
Not to mention hydrogen density/atomic size causes substantial problems for storage and transport.
but, it would seem, not in this case. iPhone. 1 week. Pain point solved.
This looks useful for military/industrial applications. It doesn't look practical for wide-spread consumer applications, any time soon.
Also I assume the recharge is pretty much instantaneous? Just re-fill it with hydrogen and you get another 7 days... That'd be pretty sweet
Heat production and water vapor are not typically desirable properties for smartphone batteries.