In lead-acid batteries, the anode is negative during discharge. The sponge lead (Pb) acts as this electrode, while lead dioxide (PbO2) is the cathode. The oxidation reaction at the anode can be expressed as: Pb + SO₄²⁻ → PbSO₄ + 2e⁻ This indicates that lead loses electrons (is oxidized), confirming its role as a negative electrode.
In lithium-ion batteries, the anode is also negative when discharging. The primary material used for this electrode is graphite. Lithium ions move from cathode to anode during charging and intercalate into graphite layers. The reaction at the anode can be represented as: Li⁺ + e⁻ + C → LiC₆
During discharge, the positive electrode is a cathode, and the negative electrode is an anode. During charge, the positive electrode is an anode, and the negative electrode is a cathode. An oxidation reaction is an electrochemical reaction that produces electrons.
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. On the other hand, the role of each electrode is switched during the discharge/charge cycle. During discharge the positive is a cathode, the negative is an anode.
When discharging, it acts as a negative electrode. Lead-Acid Batteries: Lead dioxide (PbO2) is the positive terminal during discharge, while sponge lead (Pb) is the negative terminal. Each type of battery has its unique chemistry that influences how it operates, and its components interact.
In contrast to the anode, the cathode is a positive electrode of the battery. It gets electrons and is reduced itself. Moreover, the cathode is immersed in the battery’s electrolyte solution. So, when the current is allowed to pass, the negative charges move from the anode side and reach the cathode.