TU-TESL

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On the afternoon of October 9, 2019, the Royal Swedish Academy of Sciences announced the 2019 Nobel Prize winners in chemistry, namely, John B. goodenough, M. Stanley Whittingham and Akira Yoshino, in recognition of their great contributions in the field of lithium ion. The three scientists are from the United States, the United Kingdom and Japan. With the joint efforts of the three scientists, they successfully brought lithium-ion batteries to the market, promoting the rapid development of smart phones, laptops, electric vehicles and other industries. In the 1970s, the global oil crisis broke out. According to the American media at that time, oil will soon run out, so it is urgent to use alternative energy. Wind energy and solar energy as alternative energy were widely studied at that time. But the generation of this kind of energy is determined by the weather, which leads to the instability of the electric energy produced. This is a big taboo to supply power to the grid. Therefore, a high energy density energy storage device is needed to store the electric energy generated by wind turbines or solar panels, and then stably output it to the grid. In this context, the development of high-performance batteries that can be repeatedly charged and discharged became a major direction of the scientific community at that time. Lithium metal is the smallest diameter metal in the periodic table of elements. Its density can be very large in unit volume, so when it becomes the electrode material in the battery, it can bring higher energy density. But because it is also the most active metal, when encountering oxygen, it will produce strong chemical reaction, release heat and even explode, so it is very difficult to control it. In the 1950s, there was a battery with lithium metal as the negative electrode. Under the same specification, this battery has higher capacity than other batteries, but it does not support charging and discharging. When the oil crisis broke out in the 1970s, scientists began to study how to use the characteristics of lithium to create high-capacity and reusable rechargeable batteries. In the 1970s, Stan Whittingham, a British professor at Stanford University, made a major discovery. When titanium disulfide and lithium metal are used as electrodes, lithium ions can be embedded into the layered titanium disulfide (tis2) through electrolyte to generate electric energy. And the whole process is reversible, that is, it can be charged and discharged repeatedly, which means that the electrochemical advantages of lithium metal can finally be demonstrated in the rechargeable and discharged battery! The professor is also full of confidence. With the support of ExxonMobil, an energy giant, his team quickly invested in the research and development of commercial rechargeable lithium-ion batteries. The initial stage of this project is very smooth, and the battery charging and discharging effect developed meets the expectation. But nightmares soon came to wittingham, who didn't expect that the lithium-ion battery in front of him was perfect from a chemical point of view, but it had serious defects because of a physical phenomenon. This phenomenon shows that, with the repeated charge and discharge of the battery, the negative electrode of the battery begins to generate dendritic metallic lithium crystals, known as lithium dendrites. Lithium dendrites will grow from the negative electrode of the battery to the positive electrode through the electrolyte, thus piercing the internal diaphragm of the battery, making the positive and negative electrodes short circuited, resulting in the battery heat out of control, so the professor's laboratory often has a fire accident of lithium-ion battery. Moreover, with the multiple cycles of the battery, the energy it can store becomes less and less. In the face of these two difficult problems, his rechargeable lithium battery finally failed, but this discovery laid a theoretical foundation for later research and development of a safer lithium-ion battery. Although John B. goodenough, the electrochemical legend, was not the first one to make a commercial lithium-ion battery, without him, it would be years or even decades before the commercial use of lithium-ion batteries. At that time, goodinaf concluded that there was a defect in the positive material of titanium sulfide developed by Mr. wittinghan, that is, when charging, the lithium-ion battery would constantly move from the positive material like the negative electrode, leading to the internal hollowing of the positive material, the collapse of the layered structure, leading to irreversible damage to the battery. Now, this inference has been confirmed by the industry. They found that when lithium cobalt oxide (LiCoO2) and lithium nickel oxide (nicoo2) were used as positive materials in the battery, they could transport nearly half of lithium ions to the negative electrode and generate lithium metal (negative material) on the premise of stable layered chemical structure, and the whole process was reversible. This means that as long as the anode material developed by goodinaf can be matched with the appropriate anode material, the lithium-ion rechargeable battery with large capacity and long life can be manufactured. However, due to the failure of wittingham's previous research on lithium batteries, ExxonMobil lost a lot, which made many American enterprises have no hope for lithium-ion batteries, so that goodinaf's research is not optimistic, and even his Oxford University is not willing to apply for a patent for the discovery of lithium cobaltite. Until later, goodinaf's study inspired a Japanese chemist named Akira Yoshino. At that time, Mr. Yosano worked for Asahi chemical company in Japan, where he was responsible for the development of lithium-ion rechargeable batteries. At that time, he had found a very excellent cathode material for rechargeable batteries graphite. This kind of material has the advantages of low cost, high performance and stable structure, which is the perfect match of lithium cobaltite cathode material. After seeing goodinaf's research report, Mr. Yosano Zhang successfully made the first lithium-ion battery in the world by using lithium cobaltic acid anode material and graphite anode material. There is no dangerous metal lithium in this battery. All lithium exists in the form of ionic state, which makes it safer than the lithium battery which used lithium metal as the negative electrode in the past. Therefore, the lithium-ion battery is named. Finally, Mr. Yosano's team, in cooperation with Sony, released the world's first mobile phone carrying lithium-ion batteries in 1991. Subsequently, the micro camera powered by lithium battery and notebook computers and other electronic products have been launched. Due to the high energy density of lithium-ion batteries, these electronic devices are more durable in the same volume, so it has caused a lot of sensation in the industry. In this regard, the door to the commercialization of lithium-ion batteries has opened. As for the later events, I believe many people have witnessed that with the development of lithium-ion batteries, the energy density is getting higher and higher, helping personal electronic devices such as mobile phones, laptops, smart watches to realize miniaturization, greatly improving the practicability. So far, we have learned that Mr. wittinghan discovered the phenomenon that lithium ions can be embedded into the layered structure of the positive material through the electrolyte, which inspired Mr. gudinav and enabled him to develop a stable and efficient positive material of lithium cobaltic acid. Mr. Yosano Zhang also uses the positive material of lithium cobaltic acid to combine with the negative electrode of graphite, which brings the dawn for the commercialization of lithium-ion batteries and has a profound impact on human life in the future. It seems that all three of them can be called the father of lithium-ion batteries and deserve the Nobel Prize!