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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