The World Where Salt Becomes A Battery
2020 was a significant year for electric car companies, as Tesla started the electric motors boom with its shares rising about tenfold since 2018. Numerous scientific evidences that support the idea of electric cars stopping global warming made electric motors more appealing than ever. Consequently, nowadays, we have started to witness more and more electric motor vehicles on roads. However, behind the scene, there is an unsung hero (or an evil possibly) which made all of this possible - a lithium ion battery.
Lithium ion batteries are extremely convenient and have high energy density, making them perfect as an alternative energy. However, there are abhorrent obscure facts behind lithium ion batteries which will eventually remove them from the list of alternatives. Fortunately, as always, we have found the way to solve the problem - a few years later, we will be living in the world where salt (in fact, sodium) runs a car instead of fossil fuels.
First of all, we have to know how lithium ion cells actually work. The trick behind Tesla’s lithium ion cells is using the metals with high electrochemical potential - the tendency of a metal to lose electrons. Surprisingly, Tesla wasn’t the first company to discover the secret behind the cell - it was developed by Alessandro Volta more than 200 years ago based on the concept of electrochemical potential. He took two metals with different electrochemical potentials, zinc and silver, and discovered an external flow of energy from them.
Lithium ion batteries started from the idea that lithium has the highest tendency to lose electrons, making lithium suitable as the main source of rechargeable cells. The main concept behind the operation is the fact that lithium, in its pure form, is extremely reactive. However, when it is part of a metal oxide, it is fairly stable.
Imagine there are separated lithium atoms from a lithium-cobalt oxide. Lithium atoms are highly unstable, and instantly, lithium ions and electrons will be formed. However, when lithium ions become a part of the metal oxide, they become much more stable than the previous state. Providing two different paths for electrons and lithium ions between lithium atoms and the metal oxide will let lithium atoms automatically reach the metal oxide part. During this process, we have produced electricity from the electron flow.
A practical lithium-ion cell uses the lithium-cobalt oxide as an anode and a graphite as a cathode to store the lithium. It also contains electrolyte which carries positively charged lithium ions from the anode to the cathode and vice versa. The movement of the lithium ions stimulates the movement of free electrons in the anode, creating a charge at the positive current collector. The electrical current then flows from the current collector through a cell to the negative current collector, and eventually, the cell gets charged.
In a practical cell, the graphite and metal oxide are coated onto copper and aluminum foils, which act as current collectors here
Currently, the lithium ion battery is the most popular rechargeable battery on the planet. This battery is especially popular among electric cars because compared with traditional batteries, lithium-ion batteries charge faster, last longer, and have a higher power density for more battery life in a lighter package.
However, despite its outstanding quality, there are many limitations which stop companies like Tesla from working towards the world’s transition to sustainable energy. For example, lithium is the raw material for the batteries, and it is concentrated in limited areas such as China and South America. Accordingly, it is possible to cause supply problems due to increased demand for electric cars as it is not rich in reserves on the planet. Moreover, the fact that cobalt is contained in the electrode of the lithium ion batteries is problematic; the process of extracting cobalt includes illegal child labour (including mining), raising ethical concerns.
Does that mean we can no longer use electric motors as our alternatives?
Absolutely not. On the 14th of December 2020, Tokyo University of Science(TUS) announced that researchers at the university succeeded in increasing the energy density of sodium ion batteries above lithium ion batteries. This means that the research aimed at launching the next generation rechargeable battery has made a step forward.
This is a reversal of what experts claimed was impossible a year ago.
Sodium ion batteries are emerging as an alternative, and various studies are being conducted on how they can be commercialised in various countries. Sodium (salt) for sodium-ion batteries is the sixth richest resource on earth, and it is available anywhere in the world. Moreover, cobalt does not need to be contained in sodium-ion electrodes, and the fact that the theory behind sodium ion batteries operation is the same as lithium ion batteries makes them even more competitive.
If sodium ion batteries get commercialised, the current market situation of rechargeable batteries that focus on lithium-ion batteries can be changed in one fell swoop.
Of course, further research will be needed to ensure that the materials proposed by the TUS team actually provide good longevity and low temperature operability of sodium ion batteries. However, it is noteworthy that the team has provided the momentous solution for the prevention of global warming.
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