【Mr. Goodenough is one of the most respected foreign scientists in our company. He is known as the "Father of Lithium Batteries". Fighting in the front line of lithium battery research and development, still looking for a direction for future lithium batteries, and devoting ourselves to the research of all-solid-state lithium batteries, there are only two portraits of two foreign scientists on the wall of our Shenzhen iYPOWER Co., Ltd., one is Moore, the other is an old man Goodenough】

         On the afternoon of October 9, 2019, the Royal Swedish Academy of Sciences announced the winners of the 2019 Nobel Prize in Chemistry. They are John B. Goodenough, M. Stanley Whittingham (M. Stanley Whittingham and Akira Yoshino in recognition of their great contributions to the field of lithium-ion batteries. These three scientists are from the United States, the United Kingdom, and Japan. With their joint efforts, they have successfully introduced lithium-ion batteries to the market, which has promoted the rapid development of industries such as smartphones, laptops, and electric vehicles.

         Lithium-ion battery’s life experience Chapter 1: Whittingham established the theoretical foundation

        In the 1970s, the global oil crisis broke out. According to the American media at that time, oil would soon be exhausted, and it was urgent to adopt alternative energy sources. As alternative energy sources, wind energy and solar energy were extensively studied at that time. However, the generation of this energy is determined by the sky, resulting in very unstable electric energy, which is a big taboo for power supply 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 output it stably 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-ion battery’s life experience Chapter 1: Whittingham established the theoretical foundation

Lithium metal is the metal with the smallest diameter in the periodic table of elements, and its density per unit volume can be very large, so when it becomes an electrode material in a battery, it can bring higher energy density. But because it is also the most active metal, it will produce a strong chemical reaction when it encounters oxygen, release heat, and even explode, so it is very difficult to control it.

         In the 1950s, a battery using lithium metal as the negative electrode appeared. This battery has a higher capacity than other batteries under the same specifications, 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 metal lithium are used as electrodes, lithium ions can be inserted into the layered titanium disulfide (TiS2) through the electrolyte to generate electricity. And the whole process is reversible, that is, it can be charged and discharged repeatedly, which means that the electrochemical advantages of metal lithium can finally be displayed in rechargeable and dischargeable batteries!

         The professor is also full of confidence. With the heavy funding from the energy giant ExxonMobil, his team quickly invested in the research and development of commercial rechargeable lithium-ion batteries. The initial stage of this project went smoothly, and the charging and discharging effect of the developed battery met expectations. But the nightmare soon fell on Whittingham. He never expected that the lithium-ion battery in front of him was chemically flawless, but there was a serious flaw due to a physical phenomenon.

         This phenomenon is manifested as, with the repeated charge and discharge of the battery, the negative electrode of the battery begins to form dendritic metal lithium crystals, which are scientifically known as lithium dendrites. Lithium dendrites will grow from the negative electrode of the battery to the positive electrode through the electrolyte, thereby puncturing the diaphragm inside the battery, short-circuiting the positive and negative electrodes, and causing thermal runaway of the battery. Therefore, lithium-ion battery fire accidents often occur in the professor's laboratory. And, as the battery cycles through multiple cycles, it can store less and less energy. Faced with these two thorny problems, in the end, the rechargeable lithium battery he developed ended in failure, but this discovery laid a theoretical foundation for the later development of safer lithium-ion batteries.

         The Life of Lithium-ion Batteries Chapter 2: Goodenough Finds an Excellent Cathode Material

         The Life of Lithium-ion Batteries Chapter 2: Goodenough Finds an Excellent Cathode Material

Although it was not the electrochemical legend John B. Goodenough who was the first to make commercial lithium-ion batteries, without him, I am afraid that the commercial use of lithium-ion batteries will be delayed for several years or even decades. At that time, Goodenough inferred that there was a defect in the titanium sulfide cathode material developed by Mr. Whittingham, that is, when charging, the lithium-ion battery would continuously move from the cathode material to the anode, causing the interior of the cathode material to be hollowed out. , the layered structure collapses, leading to irreversible damage to the battery. Today, this inference has been confirmed by the industry.

         They found that when lithium cobaltate (LiCoO2) and lithium nickelate (NiCoO2) are used as the positive electrode materials in the battery, they can transport nearly half of the lithium ions to the negative electrode on the premise that their layered chemical structure is stable, and generate lithium metal (negative electrode material), and the whole process is reversible. This means that the lithium battery cathode material developed by Goodenough can produce a lithium-ion rechargeable battery with large capacity and long life as long as it can be matched with a suitable negative electrode material.

         However, due to the failure of Whittingham's previous research on lithium batteries, Exxon Mobil suffered heavy losses, and many American companies had no hope for lithium-ion batteries, so that Goodenough's research did not It is not favored, and even Oxford University, where it is located, is unwilling to apply for a patent for the discovery of lithium cobalt oxide.

         Lithium-ion battery life experience Chapter 3: Akira Yoshino created the first lithium-ion battery

         Until later, Goodenough's research report inspired a Japanese chemist named Akira Yoshino. Mr. Akira Yoshino worked for Asahi Kasei Corporation in Japan at that time, where he was responsible for the research and development of lithium-ion rechargeable batteries. At that time, he had found a very good anode material for rechargeable batteries - graphite. This material has the advantages of low cost, high performance, and stable structure, and is simply a perfect match for lithium cobalt oxide cathode materials.

         After seeing Goodenough's research report, Mr. Akira Yoshino successfully manufactured the world's first lithium-ion battery using lithium cobalt oxide positive electrode materials and graphite negative electrode materials. Inside this battery, there is no dangerous metal lithium, and all lithium exists in the form of ions, which makes it safer than the previous lithium battery that uses lithium metal as the negative electrode, hence the name lithium-ion battery.

         In the end, Mr. Akira Yoshino's team cooperated with Sony to release the world's first "Big Brother" equipped with lithium-ion batteries in 1991. Subsequently, electronic products such as miniature cameras and notebook computers powered by lithium batteries came out one after another. Due to the high energy density of lithium-ion batteries, these electronic devices are more durable in the same volume, which has caused quite a stir in the industry. In this regard, the door to the commercialization of lithium-ion batteries is opened.

         As for what happened later, I believe many people have witnessed that with the development of lithium-ion batteries, the energy density is getting higher and higher, which helps the miniaturization of personal electronic devices such as mobile phones, laptops, and smart watches, and greatly improves the practicality.

         So far, we have learned that Mr. Whittingham discovered the phenomenon that lithium ions can be embedded into the layered structure of the cathode material through the electrolyte, which inspired Mr. Goodenough and enabled him to develop a stable and efficient lithium cobalt oxide cathode. Material. And Mr. Akira Yoshino combined lithium cobalt oxide positive electrode material with graphite negative electrode, which brought dawn to the commercialization of lithium-ion batteries and had a profound impact on human life in the future. From this point of view, all three people can indeed be called the father of lithium-ion batteries, and they deserve the Nobel Prize!

Source: Autohome

Author: Hu Yongbin

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