Leclanché cell

The Leclanche element is a historic galvanic element, which was developed by Georges Leclanche and 1866 patented. It represents an electric battery (primary element) and equipped in its original form with liquid electrolyte. It is thus one of the " wet " batteries no longer used. Improvements led to a gelled electrolyte, and it is a precursor of dry cell batteries, such as zinc-carbon element and the alkaline manganese battery dar.

General

The Leclanche element has a terminal voltage of 1.5 V, and consists of an anode made of zinc, which is the negative terminal, an electrolyte of ammonium chloride, and a cathode made ​​of graphite, which is the positive terminal of the cell. The cathode is to the electrolyte out by manganese dioxide ( pyrolusite ) surrounded, which acts as a depolarizer.

The Leclanche element was economically successful over many decades and was used among other things for the supply of railway telegraph and house ringing. Here, the element over the years has undergone continuous improvement: A significant improvement and a first step to the dry element was performed by replacing the liquid electrolyte saturated with ammonium chloride by wheat flour. Subsequently, the gelled electrolyte was divided by thin separator papers in sectors and increased by the addition of zinc chloride, the energy density. In the zinc anode various metal alloys and closure systems were used to reduce the evolution of hydrogen in the discharge or by exclusion of air to increase the shelf life of the elements.

Electrochemistry

The reaction equation for discharge of the cell is:

A negative electrode (anode):

A positive electrode (cathode):

Electrolyte solution ( complex formation ):

The overall reaction is obtained:

Literature sources

• Lucien F. Trueb, Paul Rüetschi: batteries and accumulators. 1st edition. Springer, 1998, ISBN 3-540-62997-1.
• H. A. Kiehn: Battery Technology Handbook. 2nd edition. Marcel Dekker Inc., 2003, ISBN 0-8247-4249-4.