Technically speaking, battery technology on cell phones and laptops is not limited to hours only. They can last for days in standby mode.
But that’s probably not what you meant.
There are three things holding back longer battery life, feel free to pick any two:
Battery type: current batteries get energy from a chemical reaction. There is only so much energy you can safely produce from chemicals in
such a way it more or less trickles out as electricity instead of just explodes in your face.
Size: It would be easy enough to give you a something the size of a car battery that would power your cell phone for weeks.
It would obviously be too heavy and cumbersome to lug around.
Cost: Believe me, companies are spending a lot of money on Research & Development to come up with batteries that last longer in a smaller space.
Graphene-based battery chemistry is probably the successor to Lithium Ion and Lithium Polymer batteries. But right now it is expensive.
Samsung is probably closest to introducing something, they will be introducing “graphene balls” that supplement the lithium ion into their cell phone batteries
as early as next year.
Eventually, there will be a breakthrough. What that will be, I don’t know. But I think that breakthrough has to come from “out of the box” thinking that somehow
does away with chemical reactions to produce energy — at least in the way it is applied today in batteries. We are probably 10 (or more) years away from
application of such a breakthrough in our personal, handheld devices.
Why is battery technology on cell phones and laptops limited to hours only? What is holding us back?