An electrolyte is a liquid, paste, or goo which conducts electricity by
allowing charged ions (atoms with extra or missing electrons) to move around
inside it. Electrolytic capacitors have a lot in common with batteries which
also use a suitable electrolyte in between two metallic plates. However, in
a battery the electrolyte reacts with the plates to drive electric charge
from one plate to the other. As a result the battery provides electric
energy from the chemical reaction which takes place as the electrolyte
corrodes the plates. In an electrolytic capacitor the reaction forms a thin
insulating layer which then blocks any further chemical action or flow
charge.
Most practical electronic electrolytes are ‘goos’ which look like icky sticky toffee pudding. Alas,
they are also fairly nasty, corrosive, toxic chemicals so they aren't exactly like toffee pudding!! Despite
that, some electrolytes are edible. For example, you can make a working battery by shoving
two plates of different metals into a lemon or a potato! However, it is unlikely that any battery or capacitor manufacturer will be put out of business by a lemon....
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