Zinc–carbon battery

The zinc-carbon cell or zinc-carbon element, often colloquially referred to as zinc -carbon battery or zinc-carbon dry cell is a galvanic cell as a chemical energy storage for the delivery of electrical energy. The zinc-carbon cell is a variant of the family of zinc - manganese dioxide cells and represents an evolution of the historic Leclanche element

General

The zinc-carbon cell is one of the primary elements since they, unlike batteries, not rechargeable. She was up in the 1970s, widely used in various sizes, but is now by far the most efficient ( lower self-discharge ) and reliable ( leakage protection ) alkaline manganese cells have been displaced.

The cell supplies a voltage of about 1.5 volts. By arranging a plurality of cells in a common casing connected in series to form a battery, the available terminal voltage can be increased. Common are still types with 4.5 V ( 3R12, " flat battery " ), 6V ( 4R25, " lantern battery " ) or 9 V ( 6F22, " 9 volt block battery ").

Construction

The zinc-carbon element consists of a molded into a cup zinc electrode ( negative pole) and manganese dioxide ( pyrolusite ) as a positive pole and a central rod made ​​of pressed carbon ( graphite) and metal cap and electrical supply. As an electrolyte, a 20 percent solution of ammonium chloride is used. The electrical load is connected between the two electrodes.

The zinc - cup which encloses the electrolyte and the " brownstone " is nearly depleted for discharged batteries. Early products had as outer covering only a cardboard sleeve. This sucked leaking electrolyte only partially. A wound metal sheath may increase the mechanical stability of the cell, as well as a plastic film under the metal sheath, the leakage resistance of the cell. The graphite pencil in the middle of the brown stone cladding has been pulled out something as a positive external contact of the cell to make better contact and provided with a metal cap.

Problems

Zinc-carbon cells are often not leakproof ( leak proof ). If there is electrolyte leakage in a device, it eats away at the battery contacts and often the traces and solder joints of adjacent boards. For this reason, one should not use cells of this type in units in which they remain longer.

There is also, as in the past Leclanche element is a problem that a zinc complex ( Diamminzinkchlorid, [Zn (NH3 ) 2] Cl2) fails. This sparingly soluble complex is at the electrodes of the element from, which increases the electrical resistance, so that in consequence the available power drops quickly.

Due to the fast sinking in the use of initial voltage and low current carrying capacity of the cell is suitable for many applications with higher load.

The self-discharge of zinc-carbon elements is significantly higher than in the partially expensive alkaline manganese cells, which complicates storage and warehousing, as well as use in safety- critical areas and degraded efficiency and environmental performance.

Reaction ( discharge)

Negative ( anode):

Positive ( cathode):

Subsequent delivery of the necessary water from the ammonium chloride electrolyte:

The resulting ammonia molecules are bound by the zinc ion complex:

Reaction of this complex with the chloride ions from the ammonium chloride:

Overall equation:

Disposal

Batteries and accumulators do not belong in household waste or in the environment because they contain environmental and recoverable materials. Zinc -carbon batteries have in Germany, as well as other batteries are disposed of correctly. Batteries selling retail stores and many recycling centers have set up for this purpose reservoir.