The Importance of Electrode Materials Used in Batteries

Following the rapid depletion of fossil fuels such as oil, coal and natural gas, one of the most crucial forms of energy storage developed by scientists in search of alternative energy sources for almost 20 years is undoubtedly the batteries. Futuristic based batteries begin with the LiCoO2 // Active Carbon battery configuration, which was produced by Sonny at the beginning of 1991 in order to take an active role, especially in the age of technology. The first battery produced was a turning point for batteries in the technology age.

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We are witnessing that there are batteries in almost every area from mobile phones to computers, from the car industry to the healthcare sector, considering the suitability of the current electronic conditions, as well as stabilizing the unstable energy from the solar and wind energy types. However, the most important point to note is the electrode materials used in the batteries and we may ask that question; why are commercial batteries the name lithium-ion battery? Most commercial batteries used today are called lithium-ion batteries. The reason for this is that the electrode material used has lithium content, or in other words, the inorganic electroactive structure in the electrode material is a derivative of lithium. For example, the first commercial battery cathode material produced by the Sony company I mentioned above was LiCoO₂. Because of this is the original ion lithium-ion that will provide electricity generation in this electroactive inorganic structure, the commercial battery produced from each lithium-containing electrode material is generally referred to as a lithium battery or a lithium-ion battery.

Well, Why Lithium?

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The working principle of the batteries is based on the redox reaction mechanism. So, the battery generates electricity by converting the energy that is emitted by the redox reaction inside it into the energy of electricity. In order for the electric energy obtained from the battery to be high, it is required that electron exchange is to be high between oxidizing and reducer. In other words, it is required that the electropositivity of the electrode material to be oxidized is high and that the electronegativity of the electrode material to be reduced is high. In this context, when we look at the periodic table, the most electropositive (or most electroactive) atom found in nature is Lithium (Li). Furthermore, since it is the lightest metal in group 1A in the activity sequence, it has a high capacity value per gram. There are many other advantages with lithium. Then why is there a different battery material seek?

Why Do We Need Alternative Battery Material Instead of Lithium?

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There are basically three criteria for a battery can take part in today's technology. These are their energy intensity or capacity, cost and to be environment-friendly. The characteristics of the commercially successful batteries have high capacity and high energy intensity, environmentally friendly and to be produced at low cost. The low cost criterion has led to investigators to search different battery derivatives. Because most of the lithium reserves are located only in Southern American Continent. In addition, lithium reserves in the earth's crust are rapidly consumed by the technological pace of development like other resources, which are limited resources. These two main reasons lead to an increase in the production cost of lithium batteries. Although today lithium batteries continue to be used extensively due to their attractive high energy density and capacity values, there is concern that these battery derivatives will disappear with the depletion of their reserves in the near future.

The most promising battery is the sodium battery after lithium. It is quite remarkable that it is the sixth largest obtainable substance in the world and it is distributed homogeneously in the earth's crust. In addition, the sodium battery is the most active material after lithium. As is known, sodium is in the same group as lithium in the group of periodic table 1A. Naturally, it exhibits electrochemical behaviors such as lithium. For this reason, when battery researchers try something new on the sodium battery, they usually copy from lithium work. The innovation efforts of sodium ion batteries have progressed very fast since this is not often misleading the researchers. Today, Aquion Energy, Faradion, such as large energy companies working on sodium and sodium batteries are in the technology. However, the disadvantage of sodium ion is that the sodium ion has a larger ionic size than the lithium ion and about 4 times the molecular weight of the sodium ion. Because of it has a high diameter it is difficult to find a suitable host material for hosting sodium. Due to its high molecular weight, the resulting capacity per unit weight and unit volume are reduced.

When the capacity value obtained from the batteries is evaluated per unit weight or per unit volume, it comes into prominence that Beryllium (Be) element should be used. One of the basic requirements of the battery was that it was environmentally friendly. So, it should not harm to both human beings and the environment. It was the greatest cause of not using excess toxic of beryllium element.

If the battery electrode material is to be handled by the reducing agent, it is desirable that the reduction be most electronegative. In other words, it is required that the maximum number of electrons is required. In this sense, we can see that the desire for electron acceptance by Francis and Radon is much higher than many metals and ametals. Even francium is the most electronegative metal. Nevertheless, it is not encountered at all that it is used in battery technology. Because atoms such as francium (Fr), radon (Ra), actinium (Ac) are highly radioactive substances. As a reducing agent, the choice is made between groups 4 and 7A more in general.

Moreover, the conductivity values are tested in high-grade materials, so that the produced energy can be used with 100 percent efficiency without being lost. In this context, materials with high electrical conductivity such as Gold (Au), Silver (Ag), Platinum (Pt) and Palladium (Pd) are encountered to be used in battery applications. However, as is known, these materials are the most expensive items on the periodic table. They are not used in commercial batteries because of they increase battery cost.

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References

• ^{Guozhong Cao ve arkadaşları, Understanding electrochemical potentials of cathode materials in rechargeable batteries Materials, Today, Volume 19, Number 2, March 2016.}
• ^{http://www.faradion.co.uk/technology/sodium-ion-technology/}
• ^{http://aquionenergy.com/technology/deep-cycle-battery/}
• ^{http://www.researchinchina.com/Htmls/Report/2009/5659.html}