Why are we not already able to “instant-charge” EVs, smartphones or other batteries?
In: Physics
Batteries don’t actually store electricity. They store energy via chemical reactions. These reactions are typically exothermic and can actually be quite harsh on batteries.
Lithium batteries in particular are surprisingly sensitive and require special charging algorithms and processes to not experience a thermal runaway.
With the current technology, the bottom 80% of the battery can be bulk charged really fast, in a matter of sometimes _minutes_, and some smartphone manufacturers do this if you have a power supply that’s beefy enough. It’s just a question of managing temperature while pumping in current, and this part of the charge cycle is pretty simple. Damage in this phase still builds over time, but it’s manageable within a normal life cycle.
The top 20% is where lithium batteries are more sensitive and require extra attention to avoid damaging the structure of the anode, cathode, and electrolyte. or triggering a thermal runaway.
This is why your phone seems to charge really quickly at first and then really slows down, still taking a full hour to charge to 100%. This also applies to EV charging, but quite often the bulk charging phase is limited by the capability of the charger instead of the battery, especially with active cooling.
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