page_title: Zinc–carbon battery
section_title: Construction
hierarchical_section_title: Zinc–carbon battery / Construction
caption_attribution_description: English: Self-drawn. A zinc-carbon battery.
context_page_description: A zinc–carbon battery is a dry cell primary battery that provides direct electric current from the electrochemical reaction between zinc and manganese dioxide. It produces a voltage of about 1.5 volts between the zinc anode, which is typically realized as a container for the battery, and a carbon rod of positive polarity, the cathode, that collects the current from the manganese dioxide electrode, giving the cell its name.
  General-purpose batteries may use an aqueous paste of ammonium chloride as electrolyte, possibly mixed with some zinc chloride solution. Heavy-duty types use a paste primarily composed of zinc chloride.
  Zinc–carbon batteries were the first commercial dry batteries, developed from the technology of the wet Leclanché cell. They made flashlights and other portable devices possible, because the battery functions in any orientation. They are still useful in low-drain or intermittent-use devices such as remote controls, flashlights, clocks or transistor radios. Zinc–carbon dry cells are single-use primary cells.
context_section_description: The container of the zinc–carbon dry cell is a zinc can. The can contains a layer of NH₄Cl or ZnCl₂ aqueous paste impregnating a paper layer that separates the zinc can from a mixture of powdered carbon (usually graphite powder) and manganese (IV) oxide (MnO₂), which is packed around a carbon rod. Carbon is the only practical conductor material because every common metal quickly corrodes in the positive electrode in salt-based electrolyte.
  Early types, and low-cost cells, use a separator consisting of a layer of starch or flour. A layer of starch-coated paper is used in modern cells, which is thinner and allows more manganese dioxide to be used. Originally cells were sealed with a layer of asphalt to prevent drying out of the electrolyte; more recently a thermoplastic washer sealant is used. The carbon rod is slightly porous, which allows accumulated hydrogen gas to escape, while retaining the aqueous electrolyte. The ratio of manganese dioxide and carbon powder in the cathode paste affects the characteristics of the cell: more carbon powder lowers internal resistance, while more manganese dioxide improves storage capacity.
  Flat cells are made for assembly into batteries with higher voltages, up to about 450 volts. Flat cells are stacked and the whole assembly is coated in wax to prevent electrolyte evaporation. Electrons flow from the anode to cathode through the wire of the attached device.
caption: Cross-section of a zinc–carbon battery
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