The evolution of the electrochemical battery
Camille Bordes
I’m sure you’ve heard of the battery. From your mobile phone to your car, these small but powerful boxes filled with chemicals power the modern world. To think that 100 years ago a battery would weigh kilos and now we carry them in our pocket: where does this technology come from and how did it start?
If you asked people when and by whom electricity was discovered, the most common answer would undoubtedly be ‘ Benjamin Franklin, 1752 ’ . If you then followed with ‘ when was the first electrical battery made? ’, most people’s first guesses would be some time in the 19 th century. Although this is in fact the time around which the first modern battery was created, the first example of a battery dates back to over 2000 years ago.
During the construction of a railway outside of Baghdad, Iraq in 1936, a team of archaeologists unearthed some vases beneath the site. Wilhem Konig was examining the uncovered sample when he discovered an unusual vase. Although its appearance on the outside was no different from any other clay vase, the inside was more complex. The inside of the vase housed a copper tube with an iron nail running down the middle of it but not touching, fixed
in place with bitumen at both ends with the iron and copper nail protruding through the stopper. It was then discovered that vase was filled with wine or vinegar. The substance that they both have in common is ethanoic acid (CH 3 COOH) which at the time could be obtained by the oxidation of the ethanol (CH 3 CH 2 OH) found in wine which, when left in the presence of oxygen (i.e., air), occurs naturally in the following reactions:
The ethanol (obtained through fermentation of crops) is oxidized to form an aldehyde (ethanal): CH 3 CH 2 OH + [O] → CH 3 CHO +H 2 O Ethanal is then oxidized further and forms a carboxylic acid (ethanoic acid): CH 2 CHO + [O] → CH 3 COOH + H 2 O When in solution, acids donate H + ions to the solution and as copper and iron are different metals, they have a
different electrochemical potential. This means that the iron nail will act as an anode and the copper nail will act as a cathode and attract the H + ions. A potential difference is then formed between the copper cylinder and the iron nail.
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