What do smartphones, camcorders, fitness trackers, and electric cars have in common? They are powered by lithium-ion batteries. Given below is the informational guide over Lithium-ion battery.
History of Lithium-ion Battery
In 2019, the Nobel Prize in Chemistry was awarded to John Goodenough, Stanley Whittingham, and Akira Yoshino for developing lithium-ion batteries. The names of the laureates were announced on October 9, but the prize is traditionally awarded in Stockholm (where Alfred Nobel was born) on December 10 (the day of his death). Three people got the prize for a reason because this very accurately reflects the fact that lithium-ion batteries were not invented at once in some random laboratory by the genius of physics, but were the result of the joint work of the world scientific community to solve a specific problem. As a result, this invention greatly affected human society. It allowed people to create such irreplaceable things today as laptops and mobile phones. And still opens new doors, for example,
How it Battery works?
The success of lithium-ion batteries can be explained by explaining how batteries work. The Italian physicist and chemist Alessandro Volta in 1800 placed zinc and copper plates in acid to produce continuous electric current, creating the world’s first chemical current source. So there was a Voltaic pole, which, after a number of improvements in design and a significant increase in efficiency, turned into a battery.
The batteries consist of an electrolyte and two electrodes: The anode is connected to the negative pole, the cathode is connected to the positive. When the battery is included in the electrical circuit, the material of which the anode consists begins to oxidize and release electrons (negatively charged particles). There are so many of them that they begin to look for a way out and move towards the positive pole. There, interact with the cathode material, the electrons are neutralized as a result of the reduction reaction.
Thus, the excess of electrons in the negative pole and their lack of positive leads to a constant redistribution of particles between the poles, which creates an electrical voltage. While the battery is connected to the electric circuit, redox processes constantly occur in it, which negatively affects the materials of the anode and cathode. This, in turn, renders the battery unusable.
How exactly Lithium-ion battery works?
Before we talk about lithium, it is worth noting two more important points.
- The more powerful the internal chemical reaction, the higher the voltage.
- If the elements that make up the battery are light and do not take up much space, then the energy density (the amount of energy per unit volume) in it will be much higher.
Lithium is a reactive element and the lightest metal of the periodic table and, based on the above, it is well suited as a material for batteries. However, its reactivity, which increases the amount of stored energy, also makes it difficult to create such an element that could be safely maintained in a charged state, divert energy using an electric current, and then return it to a charged state.
The British scientist Stanley Whittingham in the 70s of the XX century began to study superconductors and discovered an extremely energy-intensive material, which he used to create an innovative cathode in a lithium battery. It was made from titanium disulfide (TiS₂), which not only conducts current well but can also store lithium in itself.
When a piece of lithium and a piece of titanium disulfide are placed in an electrolyte, an electrochemical reaction begins. Lithium oxidizes, dissolves, and charged lithium particles (lithium ions) move into TiS₂. As mentioned above, the electrons from the anode flow to the cathode, and we get a current. But what is interesting in this circuit is that if you change the current to the opposite, then the recharging process will go on. Lithium is displaced from titanium disulfide and again becomes a piece of metal. But the first lithium battery that could be recharged
Problem Faced while making of Lithium-ion battery
- Firstly, one of the features of lithium is its tendency to form needles and dendrites (long branching structures) during the recharging process, which can lead to internal short circuits.
- The battery could explode, and titanium disulfide released hydrogen sulfide upon contact with air, which is not very pleasant and safe to breathe.
- Secondly, in 1970, the price of titanium disulfide was about a thousand dollars per kilogram (including inflation, about five thousand dollars).
- Therefore, Exxon, to which Whittingham turned to create a commercial product from his battery, abandoned the project.
How the First problem was solved?
In 1978, another British scientist John Goodenough, along with his team, began to search for more suitable material for the cathode in lithium batteries. After a series of failed experiments, he predicted that the cathode would have even greater potential if it was made using metal oxide instead of metal sulfide. Moreover, synthesizing oxides is much safer than fire hazardous sulfides. During the research, Gudenaf found that lithium cobalt oxide shows better results. It meets all safety requirements and also increases the voltage of the cell to 4 volts, that is, twice as much compared to earlier battery options.
True, the current density was too low for the use of lithium-ion batteries to be economically viable. Then the Gudenaf team put forward the assumption that with a decrease in the thickness of the electrodes to 100 microns, it will be possible to increase the current strength to the level of other types of batteries while having doubled voltage and capacity. It turned out to be true. But the last problem remained – dendrites still formed on lithium metal when recharging, which led to short circuits.
How the second problem was resolved?
In 1985, Japanese chemist Akira Yoshino created the first commercially viable lithium-ion battery, using graphite as the anode instead of lithium metal. In such a battery, lithium moves between two carrier structures (lithium cobalt oxide and graphite) and does not exist in metallic form, which eliminates the formation of needles and dendrites. The result is a lightweight, wear-resistant battery that can be charged thousands of times before its performance deteriorates. Yoshino also found ways to coat active electrode materials with a thin metal foil and was able to separate the positive and negative electrodes with a thin mesh. Only in this way was the first generation of lithium-ion batteries able to compete with the nickel-metal hydride batteries that dominated portable electronics in the early 1990s.
Present Day scenario of Lithium-ion Battery
Today, even the most advanced high-energy electrodes, such as NMC 811, which significantly increase the range of next-generation electric vehicles, are mainly made of lithium cobalt oxide. Although it is worth noting that many manufacturers often began to replace cobalt with nickel and manganese with a similar crystalline structure. This is due to the fact that, firstly, cobalt mines are quite rare. So, for 2017, 59% of all cobalt was supplied from Congo. Secondly, working conditions at these same mines leave much to be desired. Many companies are critical of the environmental performance of local mines, as well as the working conditions of miners, so they are looking for ways to avoid using this metal.
Goodenough and Yoshino have already received awards for their research and development. For example, in 2014 they were awarded the Charles Stark Draper Award. Then it was also received by the Moroccan scientist Rachid Yazami (Rachid Yazami), who in 1980 discovered that graphite copes well with the role of the cathode, while it is completely fireproof, and Yoshio Nishi (Yoshio Nishi), which is currently engaged in flexible electronics. And it is worth saying that work on improving lithium-ion batteries is ongoing. The Faraday Institution in England, the United Center for Energy Storage Research (JCESR) in the USA, the European initiative for future battery technology Batteries 2030+ is just the tip of the gigantic iceberg of institutions, initiatives and projects.
To summarize, the advantage of lithium-ion battery is that they are based not on chemical reactions that destroy the electrodes, but on lithium ions flowing back and forth between the anode and cathode. The ability to recharge and relative durability brought them to the first place among similar devices. This is currently the most popular type of battery. Almost all electronic devices use lithium-ion batteries: smartphones, tablets, smartwatches, fitness trackers, laptops, wireless mice, digital cameras, video cameras, and even electric cars. Now it’s quite difficult to imagine life without these devices, so the invention of lithium-ion batteries was noted by the Nobel Committee on Law.