Electrolytic manganese dioxide composition

The alkaline cell has an open-circuit voltage of 1.5 V that can deliver 150 Wh/kg and 460 Wh/1. The reactions have fast kinetics and can deliver full capacity, even at high-rate discharges. Since its introduction in 1959, there has been a steady increase in performance of the alkaline cell as new materials and cell components were incorporated into the structure. The present alkaline cell designs are based on the use of nanostructured electrolytic manganese dioxide, a thinner polymer gasket seal with sealant to increase internal volume and improve shelf Ufe. Mercury has been eliminated by using new zinc alloy compositions. These improvements have resulted in about a 40 % improvement in performance over the same-size cells produced in 1959. 

Depending on the composition of the active materials and on the manganese dioxide type employed, the OCV of freshly manufactured zinc-carbon cells with salt electrolyte varies between 1.55 and 1.85 V. It decreases during discharge and formation of the variable-composition mass. Upon prolonged storage of undischarged batteries, their OCV also decreases. 

The name Leclanche cell is given to the familiar primary system consisting of a zinc anode, manganese dioxide cathode and an electrolyte of ammonium chloride and zinc chloride dissolved in water. The alternative designation zinc-carbon ceir is broader and includes the so-called zinc chloride system which, due to a different electrolyte composition, is characterized by a different discharge mechanism. The Leclanche cell may be written as... 

Wang, Y. Q., A. B. Yuan, and X. L. Wang. 2008. Pseudocapacitive behaviors of nano-structured manganese dioxide/carbon nanotubes composite electrodes in mild aqueous electrolytes Effects of electrolytes and current collectors. Journal of Solid State Electrochemistry 12 1101-1107. 

The composition of a typical alkaline cathode and the purpose of each component are listed in Table 10.3. The cathode is made from a mixture of manganese dioxide and carbon. Other materials may also be added, such as binders (to help hold the cathode together) and water or electrolyte solution (to aid in forming the cathode). 

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