Batteries are so ubiquitous today that they’re almost invisible to us. Yet they are a remarkable invention with a long and storied history, and an equally exciting future.
A battery is essentially a device that stores chemical energy that is converted into electricity. Basically, batteries are small chemical reactors, with the reaction producing energetic electrons, ready to flow through the external device.
Batteries have been with us for a long time. In 1938 the Director of the Baghdad Museum found what is now referred to as the “Baghdad Battery” in the basement of the museum. Analysis dated it at around 250BC and of Mesopotamian origin.
Controversy surrounds this earliest example of a battery but suggested uses include electroplating, pain relief or a religious tingle.
American scientist and inventor Benjamin Franklin first used the term “battery” in 1749 when he was doing experiments with electricity using a set of linked capacitors.
The first true battery was invented by the Italian physicist Alessandro Volta in 1800. Volta stacked discs of copper (Cu) and zinc (Zn) separated by cloth soaked in salty water.
Wires connected to either end of the stack produced a continuous stable current. Each cell (a set of a Cu and a Zn disc and the brine) produces 0.76 Volts (V). A multiple of this value is obtained given by the number of cells that are stacked together.
One of the most enduring batteries, the lead-acid battery, was invented in 1859 and is still the technology used to start most internal combustion engine cars today. It is the oldest example of rechargeable battery.
Today batteries come in a range of sizes from large Megawatt sizes, which store the power from solar farms or substations to guarantee stable supply in entire villages or islands, down to tiny batteries like those used in electronic watches.
Batteries are based on different chemistries, which generate basic cell voltages typically in the 1.0 to 3.6 V range. The stacking of the cells in series increases the voltage, while their connection in parallel enhances the supply of current. This principle is used to add up to the required voltages and currents, all the way to the Megawatt sizes.
There is now much anticipation that battery technology is about to take another leap with new models being developed with enough capacity to store the power generated with domestic solar or wind systems and then power a home at more convenient (generally night) time for a few days
How do batteries work?
When a battery is discharged the chemical reaction produces some extra electrons as the reaction occurs. An example of a reaction that produces electrons is the oxidation of iron to produce rust. Iron reacts with oxygen and gives up electrons to the oxygen to produce iron oxide.
The standard construction of a battery is to use two metals or compounds with different chemical potentials and separate them with a porous insulator. The chemical potential is the energy stored in the atoms and bonds of the compounds, which is then imparted to the moving electrons, when these are allowed to move through the connected external device.
