In typical electric circuit where we have for example a battery and a light bulb, electrons travel through whole circuit. But what does travel when we use two electrodes and a battery in e.g. NaCl solution? What confuses me is that cathode attracts anions, so after some time won’t all anions stick to cathode and all cations stick to anode? I’ve read that ions transfer charge, but do they enter wires and then battery?
In an electrolyte the charge carriers are ions, so there is no appreciable flow of free electrons. In a wire the charge carriers are free electrons, so there is no appreciable flow of ions.
The purpose of an electrode is to provide a place for a chemical reaction to occur. This chemical reaction converts the ion-based current in the electrolyte to electron-based current in the metal. Without that chemical reaction the circuit does not complete.