The term redox consists of the first letters of the terms reduction and oxidation. Redox reactions are reactions that take place in electrochemical energy storage systems such as batteries and accumulators or in electrolysis.
A redox reaction is a transfer of electrons that consists of two partial reactions that are inseparable: a reduction and an oxidation that occur simultaneously. As far as the reduction is concerned, the reducing agent gives up electrons, reducing it by the electrons. These emitted electrons are taken up by the oxidizing agent. In practice, the two electrodes form the reducing agent and the oxidizing agent. The current flow inside a battery cell occurs as soon as the circuit outside the battery is closed and a load is switched on. The redox reaction continues until the reducing and oxidizing agents are consumed.