Dry Cell Battery
Dry cell batteries are made up of a metal electrode which is usually carbon (graphite) but can be other metals this acts as the cathode. This electrode is surrounded in an electrolyte paste which is all surrounded in a metal cylinder with the anode (usually zinc) being the wall of the cylinder.
Then zinc undergoes oxidation and the graphite undergoes reduction. When these two are both connected to a wire the electrons take the path of least interference and so they run through the wire to create an electrical current.
Vanadium redox cell;
- Chemistry; The chemistry of these two cells is very different. The vanadium redox cell has two liquid electrolytes with an electrode made of some porus and some solid graphite, as opposed to both solid in dry cell. These electrolytes are separated by an ion selective membrane. The porus graphite electrode does most of the reacting and the charge flow through the two electrolytes.
- Cost and practicality; The Vanadium redox cell is more practical than the dry cell battery as it allows 100% discharge and can remain in any state of charge for long periods of time due to the strong materials in electrodes. It is also good for use because it can be quickly recharged by simply replacing the electrolyte and the capacity for charge can be easily increased. The dry cell does not have a lot of these advantages as once it is discharged the battery is useless so it is a lot less practical. However, dry cell batteries are a lot cheaper to make and therefore are widely used today, the vanadium redox cell is still in the prototype phase but it can be produced relatively cheaply.
- Impact on society; Dry cell batteries have had a huge impact on society and have allowed the development of many portable and cordless electronic devices we use today. Vanadium redox cells are still in the prototype stage but it is hoped that when they are developed they will become a cheap and very practical solution for power needs. It is hoped it can be used extensively in electric cars.
- Environmental impact; Spent dry cell batteries can cause environmental problems with there disposal as they are made from fairly inert materials that won’t decay and they also contain some harmful acids that can damage the environment. Vanadium redox cells are more environmentally friendly as they do not need to be disposed of due to there ability to be reused and it does not use any environmentally hazardous products.
Fuel Cell;
- Chemistry; Fuels cells are electrochemical devices which combine hydrogen and oxygen to produce heat, electricity and water. They are made up of an anode, electrolyte, cathode and a catalyst. Pressurized hydrogen gas is feed into the anode side of the fuel cell where the catalyst in the form of a platinum splits it into hydrogen ions and electrons. The electrons are then put through a circuit from anode to cathode producing electricity. Oxygen gases are then feed through the cathode side of the fuel cell where the platinum catalyst breaks it up into oxygen atoms. These oxygen atoms then react with the hydrogen ions to form water.
- Cost and practicality; Fuel cells are relatively simple (they have no moving parts) to make and therefore would be reasonably cheap. However there low voltage output requires them to be in a stack to produce a reasonable amount of electricity this means many fuel cells need to be used. Hydrogen needed to power the fuel cells is hard store and distribute and is not readily available in society today, other sources such as methanol are being considered for use in fuel cells.
- Impact on society; Fuel cells are destined to have a large impact on society and are destined for use in motors, lights and any other electrical appliances. Fuel cells high efficiency compared to combustion engines and batteries gives it an advantage over those sources.
- Environmental Impact; Fuel cells are very environmentally friendly as their only emissions are water and heat. Pollution Reduction is one of the primary reason for production of this technology. There may be environment problems associated with the production and storage of hydrogen and a fuel.
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