Dry Cell & Lithium Cell

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Dry Cell & Lithium Cell

Dry Cell

Chemistry –

Anode: Zinc
The anode is a can of zinc which contains a mixture and an electrolyte of MnO2 and an electrolyte paste of NH4Cl, ZnCl2, H2O and starch. To improve its conductivity, powdered graphite may be added. Anode Reaction:

Zn(s) ( Zn2+(aq) + 2e-

Cathode: Graphite Rod
The cathode is an inactive graphite rod. This graphite is a form of elemental carbon. Its reaction is rather complex. MnO2(s) is reduced to Mn2O3 through a series of steps that may involve the presence of Mn2+ and an acid-base reaction between NH4+ and OH-. Cathode Reaction:

2MnO2(s) + 2NH4+(aq) + 2e- ( Mn2O3(s) + 2NH3(aq) + H2O(l)
The ammonia, forms a complex ion with Zn, which crystallizes in contact with the Cl- Zn2+(aq) + 2NH3(aq) + 2Cl-(aq) ( Zn(NH3)2Cl2(s)

Overall cell reaction:
2MnO2(s) + 2NH4Cl(aq) + Zn(s) ( Zn(NH3)2Cl2(s) + H2O(l) + Mn2O3(s)

Cost & Practicality -

A dry cell battery is rather cheap to manufacture and therefore making it rather cheap to purchase. This helps in overcoming the non-rechargeable disadvantage. It is practical because it is available in varying sizes.

Depending on sizes, it doesn’t weigh much. Therefore making it easy to carry in portable devices. Disadvantages are that it can also develop leaks and has a short shelf life due to the acidic paste.

Impact on Society –

It was the first commercial battery which made it a widely used, common household item. This is because it is inexpensive and can be easily replaced. It is used for low drain appliances, which only need small currents. Eg. radios, torches, clocks, television remotes.

Environmental Impact –

The acidic paste is weak and the reaction products are non-toxic. This allows for an unproblematic disposal in dumps that causes little environmental impact.

Lithium Cell

Chemistry –

Anode: Lithium
The anode is lithium. The battery contains an electrolyte, which is a polymer that allows Li+...
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