The electrons in the external circuit flow from the negative electrode to the positive electrode; Anions in the internal circuit (electrolyte solution) move to the negative electrode and cations move to the positive electrode; The directional movement of electrons forms current, which realizes the transformation from chemical energy to electrical energy.
The flow direction of ions in the electrolytic cell is the attraction of yin and yang, that is, cations flow to the cathode and anions flow to the anode.
When discharging, current flows from the positive electrode to the negative electrode, and electrons flow from the negative electrode to the positive electrode. So there are many electrons attached to the positive electrode, which will attract cations. But in the process of charging the electrolytic cell, only the anode and cathode are separated. Because it is powered by power supply, the cathode is covered with a large number of electrons, which will attract cations, so the cathode attracts cations and the anode attracts anions. The process of charging and discharging is actually the process of electrolytic cell and primary battery.
The device that generates current through redox reaction is called primary battery, which can also be said to be a device that converts chemical energy into electrical energy. Some primary batteries can form reversible batteries, while others cannot. When the primary battery is discharged, the negative electrode undergoes an oxidation reaction and the positive electrode undergoes a reduction reaction. For example, a copper-zinc primary battery, also known as Danielle battery, has a copper anode immersed in sulfuric acid solution; The negative electrode is a zinc plate immersed in zinc sulfate solution. The two electrolyte solutions are connected by a salt bridge, and the two electrodes are connected by wires to form a primary battery. Usually used dry batteries are made according to the principle of primary batteries.
References:
Baidu encyclopedia-primary battery