Dry Cell
Definition and meaning of Dry Cell in chemistry.
A dry cell is a primary (non-rechargeable) electrochemical cell in which the electrolyte is held as a moist paste rather than a free-flowing liquid, so the cell can be sealed and used in any orientation.
In more detail
In the common zinc-carbon (Leclanché-type) dry cell, a zinc container serves as the anode and is oxidized to Zn2+, while an inert carbon rod at the center acts as the cathode. Surrounding the carbon rod is a paste of manganese(IV) oxide, ammonium chloride, and zinc chloride that conducts ions between the electrodes and also acts as a depolarizer, oxidizing the hydrogen gas produced at the cathode so the voltage does not drop quickly. Because the reactants are consumed irreversibly as the cell discharges, a dry cell cannot be recharged once it goes flat, unlike a rechargeable secondary cell.
Key facts
| Typical voltage | ~1.5 V |
|---|---|
| Anode | Zinc casing (Zn → Zn2+ + 2e−) |
| Cathode/electrolyte | Carbon rod in MnO2/NH4Cl/ZnCl2 paste |
| Field | Physical Chemistry |
A standard zinc-carbon AA battery, commonly used in flashlights and remote controls, is a dry cell that produces about 1.5 volts.
Frequently asked questions
Why is it called a 'dry' cell if it contains a paste?
It is called dry because the electrolyte is immobilized as a moist paste rather than existing as a free liquid, in contrast to earlier 'wet' cells that used a liquid electrolyte in an open container.
Can a dry cell be recharged?
No. A standard zinc-carbon dry cell is a primary cell whose electrode reactions are not efficiently reversible, so once the reactants are used up the cell must be discarded, not recharged.