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Scientists have come closer to developing a greener alternative to the lithium-ion battery, one based on salt! That’s right, salt — something that we use daily and is found in abundance in nature. The implications of this discovery lie in several industries such as automotive electric cars, various electronic technologies, in addition to wind and solar alternative energy solutions. In the new study, researchers from MIT, University of Southern Denmark and University of Copenhagen, have found a way to make the sodium-ion battery more energy efficient. This was accomplished by tuning the battery composition through the addition of manganese. Manganese is a transition metal that has a half-filled d-shell, which in chemistry indicates its stability, as well as the potential for multiple oxidation states. The presence of manganese helps in the charging process, and allows the battery to have higher voltage or longer battery life, and potentially higher battery capacity, or the ability to store more energy. In order to understand the full significance and the impact of this discovery, let’s go back understand why batteries are important and the rationale for making a salt based batteries, as opposed to a lithium-ion ones.
The importance of lithium-ion batteries can not be understated, as they are used in virtually every device. To add to that, just a couple of months back, in October of 2019, the Nobel committee announced that the Nobel Prize in Chemistry would go to the three scientists, John B. Goodenough, M. Stanley Whittingham and Akira Yoshino, who were instrumental in the development of lithium-ion batteries, underscoring the importance of their work both in the scientific community, as well as its impact in industrial applications.
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Lithium-ion batteries came about as a replacement for their predecessor, lead-acid batteries, which were both very heavy and dangerous, in addition to having significant environmental and toxicity concerns. Lithium-ion batteries on the other hand offered a safer and more efficient alternative. However, when scientists made the lithium-ion battery, they tested a slew of other metals besides lithium. One of them was sodium, which happens to be in the same group as lithium and shares its chemical properties but differs in size. Due to the size difference, sodium travels slower from one electrode to another, thereby affecting the charge process of batteries. Thus, lithium being smaller, was faster and was one of the reasons as to why it was chosen as the optimal ion for the making of the battery. However, today due to the ubiquitous presence of electronic devices, which heavily rely on lithium-ion batteries, the process of mining lithium possess certain environmental and social concerns. In addition to that, cobalt is another element which is used for making a lithium-ion battery, which also has raised ethical concerns in regards to its mining operations. Moreover, cobalt is expensive.
The sodium-ion battery gets around both of those issues. For one, it does not need to rely on cobalt, and secondly sodium is readily available in deposits of the ocean floor. Another advantage is that due to the similar chemistry of lithium and sodium, many of the materials that were tested or used for lithium can be used for sodium as well. From the production side, it will be easy to adapt factories that were used to produce lithium-ion batteries to sodium-ion ones with a bit of effort. However, this all comes with a caveat.
Lithium and sodium are inherently different elements, therefore no matter how similar they may behave, they are still different and that is why research is necessary in figuring out a way to build an efficient sodium-ion battery. In addition to that, their chemistry predisposes them to different applications. In the case of sodium, being larger, the amount of energy that can be stored per unit of volume decreases, as does the time it would take to charge them. Therefore, the sodium-ion batteries would function better if size of the battery could be bigger. This means it may be best suited to power things that are of stationary nature, which points to applications in the fields of alternative energy fields. Wind and solar make good candidates because they are stationary and also because since wind or sun is not present all the time, the source of energy fluctuates, thus making energy output inconsistent throughout time. Therefore, having a battery store energy and supply it for a more consistent output is beneficial. In fact such an application occurred last year in China's Jiangsu Province, where a sodium-ion battery was used as a storage plant to regulate energy, “storing energy during low consumption hours and delivering electricity during peak hours,” according to Chinese Academy of Science.
Sources of information:https:https://www.forbes.com/sites/annapowers/2020/01/31/your-next-battery-could-be-made-from-salt-scientists-make-greener-advances/#5000de2043a5
