One disagreement that happened more than 2000 years ago resulted in an invention that became the basis for a widely used product today. The first ‘battery’, the voltaic pile, was invented by Alessandro Volta in 1800, a disagreement with Luigi Galvani having spurred its development. (Yes, the terms voltage and galvanize came from their names) Batteries back then and today still rely on the same concept of ‘electrochemistry’. Batteries can store energy in the form of chemical energy and release it as electrical energy when needed. This has made it extremely useful for electronics that must be moved around and can’t be attached to stationary power sources. They are made up of electrochemical cells that carry out the same reactions. (National MagLab, n.d.)
In a usual cell, there would be two half-cells, each containing an electrode and a suitable electrolyte. In each half-cell, a redox reaction would take place at the electrode. At the anode, oxidation occurs with the formation of cations from the cathode, as its oxidation state increases with the removal of electrons. This results in the anode wanting to donate electrons. At the cathode, reduction occurs where cations from the electrolyte gain an electron, and their oxidation state decreases. This results in the cathode needing more electrons. Since one side wants to donate its electrons while the other wants to receive electrons, a potential difference is created between the two electrodes, allowing electrons to travel from the anode to the cathode, generating electricity. The electrolytes provide ions that enable the cell to remain electrically neutral as the ions not involved in the reaction would be able to balance the charge in the other half of the cell since the redox reactions generate new ions. Without electrical neutrality, the conditions would no longer be favorable for the redox reactions to take place. The salt bridge prevents the flow of electrons and only facilitates the flow of ions between the half cells so that a short circuit is not created. Throughout these reactions, the electrodes would be used up, hence why some batteries are only single-use as the reactions involved in those batteries are irreversible.
However, in rechargeable batteries, the reactions that take place can be reversible, allowing for the original state of the cell to be reformed so that the process can be repeated. This is done through electrolysis. During electrolysis, an external electrical source is used to force electrons in the opposite direction than before. The electrode that used to be the anode will now receive electrons, becoming the cathode where reduction occurs. The cations produced before would now have to receive an electron, reforming their original state. The reverse happens for the other half of the cell. (Chemistry LibreTexts, 2019)
Hence, with the original state of the battery reformed, it can continue to be used and recharged.
It is important to note that batteries contain chemicals that can be extremely toxic and dangerous, as many are strong acids or bases. This is why we should follow the proper procedures for disposing of the batteries.
Reference list
Chemistry LibreTexts. (2019). 8.3: Electrochemistry- Cells and Batteries. [online] Available at: https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Chemistry_for_Changing_Times_(Hill_and_McCreary)/08%3A_Oxidation_and_Reduction/8.03%3A_Electrochemistry-_Cells_and_Batteries.
Laboratory, N.H.M.F. (n.d.). Voltaic Pile – 1800 - Magnet Academy. [online] nationalmaglab.org. Available at: https://nationalmaglab.org/magnet-academy/history-of-electricity-magnetism/museum/voltaic-pile-1800/.
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