I’m pretty aware that this is a “dumb” question, but my basic understanding of electricity can’t figure it out. I know the basic concept of resistance, currency and voltage, but I can’t comprehend how it takes so long to store charge in a battery
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Electricity “spreads” fast, and individual electrons *can* be fast.
But to fill a capacitor you need a lot of electrons, and the more there are already the harder it gets to add more. And batteries are also limited by the reaction speed of the chemicals inside.
So as an example if you connect a capacitor through a long wire to a 5V source. The 5V will reach the input of the capacitor at the speed of light, but that’s just “electrical pressure”, no electrons moving yet. This pressure then starts moving electrons through the wire depending on it’s resistance. A voltage accelerates an electron until it hits an atom in the wire and is slowed down again, so they mostly just bounce around with a general trend to move forward.
The classic analogy is a waterhose. If it’s already filled with water opening the tap will (almost) instantly push some water out of the front. But only because that happens fast doesn’t mean you can fill an olympic pool in a second. Equally you can make the individual water particles very fast by using a thin hose, but that doesn’t help you filling the pool either, it gets faster but there is less of it.
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