Zinc–carbon battery

[5] It produces a voltage of about 1.5 volts between the zinc anode, which is typically constructed as a cylindrical container for the battery cell, and a carbon rod surrounded by a compound with a higher Standard electrode potential (positive polarity), known as the cathode, that collects the current from the manganese dioxide electrode.

The name "zinc-carbon" is slightly misleading as it implies that carbon is acting as the oxidizing agent rather than the manganese dioxide.

They made flashlights and other portable devices possible, because the battery provided a higher energy density at a lower cost than previously available cells.

In 1886, Carl Gassner patented a "dry" version by using a casing made of zinc sheet metal as the anode and a paste of plaster of Paris (and later, graphite powder).

Zinc-chloride cells (usually marketed as "heavy duty" batteries) use a higher concentration of anolyte (or anode electrolyte) which is primarily composed of zinc chloride, which can produce a more consistent voltage output in high drain applications.

The bottom and sides of the can contains a paper separator layer which is impregnated with ammonium chloride (NH4Cl) along with a thickening agent to form an aqueous electrolyte paste.

The paper separator prevents a short circuit from forming by protecting the zinc can from making contact with the cathode, which is a mixture of powdered carbon (usually graphite powder) and manganese (IV) oxide (MnO2), which is packed around a carbon rod.

Originally cells were sealed with a layer of asphalt to prevent drying out of the electrolyte; more recently, a thermoplastic washer seal is used to help prevent leakage as well as to contain any internal pressure which may form as a result of hydrogen gas buildup during discharge.

[12] Zinc–carbon batteries have a lower per unit cost and are often used as power for appliances that consume little energy, like remote controls for television, clocks, and smoke detectors.

Zinc-carbon batteries were in common use with hand-cranked telephone magneto phones, powering the microphone and speaker.

Side reactions and depletion of the active chemicals increases the internal resistance of the battery, which causes the terminal voltage to drop under load.

The battery shown at (c) had a polyethylene protection film (mostly removed in the photo) to keep the zinc oxide inside the casing.