Battery

A current is produced basically by the flow of electrons. The dry cell, or Leclanche battery works by creating two electrochemically different ends (an anode and a cathode) so current passes through when a complete circuit is connected. This involves non-renewable compounds which initiate reactions at both ends of the cell. These reactions allow the flow of ions which ultimately produce the current.

Diagram 1: The make-up of a dry cell

Diagram 1 shows the composition of the cell initially. As the cell is used zinc ions are formed and ammonium ions are discharged. The zinc reaction occurs at the anode: Zn 刜 Zn2+ + 2e-

While at the cathode: NH4+ + MnO2 + H2O + e- 刜 Mn(OH)3 + NH3

The reduction of Manganese from 4+ to 3+ produces a voltage of about 1.5V.

The dry cell is the cheapest commercially available battery. Depending on the relative size, each battery can be worth less than $3. In our fast paced modern world of electricity and communication the dry cell battery is widely used in items such as torches

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THE VANADIUM REDOX CELL

CHEMISTRY:

The vanadium redox battery, unlike the dry cell is much more complicated. In disposal the manganese (III) is oxidized to insoluble manganese (IV), and the small amounts of zinc, ammonium salts and carbon make the batteries harmless. It is the migration of ions that produces the resulting current to power the appliance.

ENVIRONMENTAL IMPACT:

The VRB has been referred to as ¨The Green Battery〃 due to the materials used in itˇs construction and for itˇs ability to integrate with natural power sources such as wind and solar. It has provided another option for industry as a power supply. This means comparatively to the dry cell it is equally effective. , walkmans and other music players, calculators, clocks and toys.

COST AND PRACTICALITY:

The vanadium redox battery is a low maintenance cell. These are stored in mild electrolyte sulfuric acid solutions. The net efficiency of this battery can be as high as 85%. It is a constant source of reliable current.

Diagram 2 shows the cell during action.

iagram 2: The make-up of a vanadium redox cell.

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