The evolution of energy storage
Batteries are so universal today that they’re almost completely overlooked and taken for granted by us. Yet they are a one of the most remarkable technologies we have developed with a history which we can be traced back to around 250BC.
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. American scientist and inventor and former President of the United Sates, Benjamin Franklin coined the term
“battery” in 1749.
The first modern battery was invented in Italy by the physicist Alessandro Volta in 1800. Volta (hence the term Volt)
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.
The batteries that most of us grew up with, the lead-acid battery, was invented in 1859 and is still the technology used
to start most internal combustion engine cars today and the first example of a rechargeable battery.
There is now no longer any real debate that battery technology is about to take another great leap forward as we move
into the post fossil fuel age, with new technologies being developed with enough capacity to store the power generated
in smart girds from solar or wind systems and then power a home, or our vehicles or even be resold back to utility
companies, when the sun isn’t shining or the wind blowing.
How do batteries work?
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.
A conducting fluid such as salt and water is used to transfer soluble ions from one metal to the other during the
reaction and is called the electrolyte. The metal or compound that loses the electrons during discharge is called
the anode and the metal or compound that accepts the electrons is called the cathode. This flow of electrons
from the anode to the cathode through the external connection is what we use to run our electronic devices.
nickel-cadmium battery (NiCd), nickel-metal hydrogen batteries (NiMH) rechargeable batteries
One of the earliest rechargeable batteries, the nickel-cadmium battery (NiCd), uses an alkali as an electrolyte.
In 1989 nickel-metal hydrogen batteries (NiMH) were developed, and had a longer life than NiCd batteries.
Portable applications – such as mobile phones and laptop computers – originally used these systems, however
these types of batteries are very sensitive to overcharging and overheating during charge and as larger
applications of batteries are contemplated the safety in large format and large quantity of cells has
become a more significant consideration.
In the periodic table lithium (Li) is one of the lightest elements with the largest electrochemical potentials;
it is this combination that produces some of the highest possible voltages in the most compact and lightest
volumes; this is the basis for the lithium-ion battery.
In 1980, the American physicist Professor John Goodenough invented a new type of lithium battery in which
the lithium could transfer energy through the battery from one electrode to the other as a Li+ ion (lithium-ion).
He found that by combining metals – such as cobalt, nickel, manganese or iron – and oxygen to form the
cathode, when recharging and a voltage being created, this positively charged lithium ion from the cathode
to the graphite anode, becoming lithium metal.
Due to the inherently strong electrochemical forces in lithium that can be oxidised, as it migrates back to the
cathode it becomes a Li+ ion again and gives up its electron back to the cobalt ion. It is this migration of electrons
back and forth in the circuit that creates the electrical current that we now rely upon..
The big leap forward: nano technology
The ability to make battery cathodes from nano-scale material was out of the question up until the same
physicist who originally recognized the potential of lithium-ion batteries, Professor Goodenough made a
huge leap in battery technology by introducing a stable lithium-ion cathode based on lithium iron.
This has led to the development of lithium iron phosphate (LiFePO4) or lithium Ferro phosphate (LFP)
materials which can now be made safely into large format cells that can be rapidly charged and discharged.
From power tools to hybrid and electric vehicles, we now rely upon this development in battery technology,
but perhaps the most important application will be the holy grail of battery storage; the storage of domestic
electric energy for our homes, vehicles and businesses.