These electrodes are often made of an inert material such as stainless steel, platinum, or graphite. The liquid to be electrolyzed must be able to conduct electricity, and so it is usually an aqueous solution of an electrolyte or a molten ionic compound.
The electrodes are connected by wires to a battery or other source of direct current. The electrode from which electrons are removed becomes positively charged, while the electrode to which they are supplied has an excess of electrons and a negative charge. The negatively charged electrode will attract positive ions cations toward it from the solution. It can donate some of its excess electrons to such cations or to other species in the liquid being electrolyzed.
Hence this electrode is in effect a reducing agent. In any electrochemical cell electrolytic or galvanic the electrode at which reduction occurs is called the cathode. The positive electrode, on the other hand, will attract negative ions anions toward itself. This electrode can accept electrons from those negative ions or other species in the solution and hence behaves as an oxidizing agent. In any electrochemical cell the anode is the electrode at which oxidation occurs.
The electromotive force, emf in V, of the battery is the difference between the potentials of the positive and the negative electrodes when the battery is not working.
During the battery discharge, the cell voltage U , I. Figure 2: Discharge and charge of a battery: left, potential change of the positive and negative electrodes; right, battery voltage change.
During a battery charge, the cell voltage U , the difference between positive and negative, increases Figs. During normal use of a rechargeable battery, the potential of the positive electrode, in both discharge and recharge, remains greater than the potential of the negative electrode. Texts describing battery anodes or cathodes certainly implicitly consider the case of the discharge.
Let us not hesitate to write, paraphrasing Rutherford, implicit is nothing but poor explicit. Battery cyclers Overview Research grade Ultra-precision battery cyclers Accessories.
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