All electrochemical cells consist of two electrodes separated by some distance. The space between the electrodes is filled with an electrolyte--an ionic liquid or solid that conducts electricity. One electrode--the anode--permits electrons to flow out of it. The other--the cathode--receives them.the electrochemical reaction involving an anode, cathode and electrolyte. In a rechargeable battery, however, the reaction is reversible. When electrical energy from an outside source is applied to a secondary cell, the negative-to-positive electron flow that occurs during discharge is reversed, and the cell's charge is restored.The most common rechargeable batteries on the market today are lithium-ion (LiOn), though nickel-metal hydride (NiMH) and nickel-cadmium (NiCd) batteries.