Why are we not already able to “instant-charge” EVs, smartphones or other batteries?
In: Physics
There’s two problems with this idea. First, let’s understand what electricity is: the flow of electrons. For simplicity, imagine a wire as a hose carrying water. Imagine a battery as a bucket.
There’s a max rate for how much water your hose can deliver per second. The same is true for the wires in your home: there’s a max limit to how much power they can deliver per second.
There’s also a max rate for how much water a bucket can take per second. If you exceed this rate, then you end up spilling water instead of getting it into the bucket.
But this metaphor breaks down: electricity is much more complicated that water. Electrons repel each other. They don’t want to be packed together. The more electrons you have in a material, the harder it is to put more in there.
The way we pack lots of electrons together is through a variety of chemical reactions, which can only occur at specific rates. Going too quickly can cause the chemical reaction to fail to execute in some of the battery, leaving empty capacity and possibly damaging it permanently.
If you try to fill a battery up too fast, it overheats and can even catch on fire.
Note: we are actually moving “ions” around to charge batteries, not just packing in electrons, but for the sake of ELI5 I’ve simplified a lot of concepts here.
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