What stops us from producing portable batteries for handheld devices like phones or laptops that would allow us to use such devices for weeks or months continuously?
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Your laptop and phone does have a portable battery in it?
Nothing.
But nobody wants to have a laptop that’s four inches thick to contain a battery large enough for all that power.
Similar charges repel, like when you try to push two magnets together the wrong way. The limit to our battery technology is, at one level, the limit of how much charge can be pushed into a limited volume.
We can only make batteries of a certain quality, it’s an area of very active research to make better ones. At the moment, to power a typical smartphone for a week would need a battery many times bigger and heavier than the ones they currently have, and most people don’t want a phone that’s way bigger and heavier than the one they currently have just so the battery lasts a week.
We do have those, they just weigh so much nobody wants to carry them. At this point it is more convenient to just charge every now and then. Some phones dedicated to travel/rural areas do include a bigger battery and/or reduce features like screensize or prozess power to increase battery life.
Take any battery that is in current electric cars and use those to charge a phone and you could go a pretty long time. You just would have to carry it everywhere. There are actually some that do this, basically use the cars battery (or a dedicated one) with a charging/usb port. Used to be able to drain the car dead, modern cars usually solve this by separating them.
Many other designs and solutions exist ofc, including powerbanks of varying size.
A couple of years ago Samsung tried to push more charge than what was prudent into their brand new flagship phone.
Things got a little explody…
There’s a physical limit of how much energy you can store in current battery material before it gets all burny and explody.
In the future we’ll be able to store more, but right now we’re at the limit with current battery chemistry.
The critical variable for battery life is quite simply the energy density, telling you how much energy per cubic centimeter you can store.
So let’s say we measure energy in hours (of device usage), and your phone has a 6 cm^3 battery which lasts for 24 hours of usage. Your energy density is now 4 hours per cubic centimeter. A month has 720 hours, so if we divide that with our energy density, we would get 180 cm^3 as the volume of a battery that would last a month without recharge. Is that a lot? Yeah, it’s about the same as a full cup of coffee. So the reason why you don’t have a month long battery life is simply the same as why you don’t carry around a coffee mug in your pocket – it’s quite inconvenient.
The second reason is safety. If you store an enormous amount of energy, then in the case of a technical mishap, that same amount of energy may be quite explosively released into its environment. You probably also understand why storing explosives in your pocket is a bad idea.
Obviously, the first issue of volume could be solved by using a material with a higher energy density. But inventing such a material that has a high energy density, is stable in regular usage, is safe and reasonably cheap to produce is hardly trivial, development of such a material can easily be a billion-euro business. But the safety issue is harder, storing more energy inherently makes malfunctions more risky, no way to get around it, really.
Most people here need to re read the question. It’s not “why don’t we make the battery in our phones so big we can use it for weeks” it’s “why don’t we have separate batteries that can be changed like in a flashlight”
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