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Leclanché cell[lə¦klan¦shā ‚sel]
a galvanic cell with a manganese dioxide-graphite-carbon black positive electrode and a negative electrode of zinc. The original cell was developed in 1865 by the French chemist G. Leclanché.
The original Leclanché cell consisted of a zinc cup filled with an aqueous solution of ammonium or other chloride (the electrolyte), in which was placed a sintered cake of manganese dioxide with a carbon terminal. In more recent designs (the “dry” Leclanché cell), the electrolyte is thickened with a starchy substance. The initial voltage of such a cell is 1.4–1.6 V, and the final value is 0.7–0.9 V. The specific energy is 30–50 W.hr/kg. A flat type of cell was developed during the 1930’s and 1940’s with a specific energy of 40–60 W.hr/kg. During the 1960’s, a Leclanché cell appeared with an alkaline electrolyte of potassium hydroxide (1.4–1.6 V initial, 0.9–1.0 V final, 60–90 W-hr/kg); this has gradually been supplanting the cells of the salt-electrolyte type.
Leclanché cells are the cheapest and most convenient chemical sources of current: they keep well, they are portable, they need no special care, and they are always ready to operate. They are used extensively to power portable radios, flashlights, electric clocks, and electric toys.