The Nobel Prize in Chemistry was awarded to John Goodenough, University of Texas at Austin, Stanley Wittingham, State University of New York at Bingham, and Akira Yoshino from Asahi Kasei Co., Ltd. in recognition of their research and development of lithium-ion batteries. Outstanding contribution. So, how are lithium batteries developed? What will be the future development?
1 There is no mobile smart life without lithium batteries
We have already lived in a "rechargeable world", but it is the lithium battery that truly brings the portability of electronic devices and opens up modern mobile life. It can be said that if there is no lithium battery, there will be no mobile smart life we are now.
Lithium batteries are widely used in various fields from mobile phones to notebook computers because of their light weight, rechargeability, powerful functions and portability. It is used worldwide to power portable electronic devices, and we use these portable electronic devices for communication, work, study and entertainment.
Lithium batteries have also promoted the development of long-lasting electric vehicles and energy storage from renewable energy sources (such as solar and wind energy), laying the foundation for a wireless (mobile), fossil-fuel-free society. It can be said that as an energy storage device, lithium-ion batteries have completely changed human life.
The Nobel Prize in Chemistry was awarded to three scientists in the field of lithium battery. It is a recognition for every lithium battery practitioner who has made contributions to the commercialization of lithium batteries from scratch and from the laboratory to the commercialization of lithium batteries. It is a recognition that they are still engaged in lithium battery research. Hezhi is an incentive for people who continue to promote the development of a clean and portable society.
2 The oil crisis directly contributed to the research and development of lithium batteries
In the 1970s, the oil crisis directly contributed to the research and development of lithium batteries. The American oil giant Exxon judged that oil resources, as a typical non-renewable resource, will face exhaustion in the near future, so they formed a team to develop the next generation of energy technology that replaces fossil fuels.
The lithium battery is one of the new batteries proposed by people. At that time, Stanley Wittingham, who worked for Exxon, proposed a new material titanium disulfide as a positive electrode material, which can store lithium ions between molecular layers. When it is matched with the metal lithium negative electrode, the battery voltage is as high as 2V.
However, due to the high activity of the metal lithium negative electrode, which brings great safety risks, this kind of battery has not been promoted. But scientists have not given up on exploration. Since the problem lies in the electrode material, perhaps replacing the electrode can solve the problem.
Goodenough, who was the director of the Inorganic Chemistry Laboratory at the University of Oxford in the UK at the time, concluded that using metal oxides instead of sulfides as the positive electrode can achieve higher voltages and improve the performance of lithium-ion batteries.
In 1980, Goodenough used lithium cobalt oxide as the positive electrode of the battery, which could increase the battery voltage to 4V. The emergence of lithium cobalt oxide is a great breakthrough in the field of lithium-ion batteries, and it is still the main cathode material for portable batteries.
3 The first commercial lithium battery appeared in the 1990s
However, due to the unstable characteristics of metal lithium negative electrodes, the safety of lithium-ion batteries was still a serious problem at that time. In 1985, Japanese scientist Akira Yoshino used petroleum coke instead of metal lithium as the negative electrode and lithium cobalt oxide as the positive electrode, inventing the first commercial lithium-ion battery. In 1991, Sony Corporation of Japan released the first commercial lithium-ion battery.
After more than 30 years of industrial development, the energy density, cost and safety of lithium-ion batteries have made great progress, and have penetrated into all aspects of our lives.
Among the currently widely used commercial lithium batteries, lithium ions are randomly "chained back and forth" in the "master" home who uses special layered materials as the positive and negative electrodes of the battery to complete the charge and discharge of the battery.
It should be pointed out that although the "stop-in" process of lithium ion insertion and extraction does not affect the material structure of the "master" at home, the whole process is still a chemical reaction rather than a physical reaction.
4 Lithium batteries still have a lot of room for development
This year's Nobel Prize in Chemistry awarded to the field of lithium batteries is a huge affirmation and encouragement to this industry. Lithium batteries are still facing many arduous challenges from the birth and development to the application and promotion.
Since Sony`s commercial production of the first batch of lithium-ion batteries in 1991, the above-mentioned [rocking-chair batteries" that [dropped in" with lithium-ion batteries have become the most promising and fastest-growing market. However, restricted by the principle of lithium-ion batteries, the energy density of lithium-ion batteries in the existing system has dropped from an annual growth rate of 7% to 2%, and is gradually approaching its theoretical limit. On the contrary, with the progress of society, people's demand for portable and clean life becomes stronger.
The use of electrode materials with less mass to store more electricity is expected to build a lithium ion battery with higher energy density. The specific capacity of metallic lithium is as high as 3860mAh/g, which is the ultimate material for constructing high specific energy batteries. However, if lithium metal is directly used as the negative electrode material of the battery, there is always a "tarsus maggot"-dendrite. In the face of this "enemy" that causes potential safety hazards for lithium batteries, scientists from all over the world are making unremitting efforts.
5 Dealing with the "dendrite", the enemy of lithium battery safety
As we all know, a battery is divided into a positive electrode, a negative electrode, and an electrolyte. Electric current is generated through an oxidation-reduction reaction. When discharging, ions flow from the negative electrode to the positive electrode, and when charging, they flow from the positive electrode to the negative electrode.
For lithium batteries, lithium will be oxidized into ions during discharge and enter the electrolyte and finally reach the positive electrode; when recharged, these lithium ions will redeposit on the surface of the lithium metal negative electrode.
However, this deposition is often uneven. With the frequent use of lithium batteries, needle-like or dendritic lithium dendrites will grow on the surface of lithium metal. If the dendrite grows too long, it will break and will no longer participate in the reaction, causing irreversible capacity loss to the battery system. The most dangerous thing is that the grown dendrite will pierce the separator between the positive and negative electrodes of the battery, causing a short circuit. Buried potential safety hazards of battery overheating, spontaneous combustion or explosion.
In the field of lithium battery, how to achieve "both fish and bear's paw"? How to achieve a higher energy density, safer, and faster charging energy storage process by proposing new principles, new systems, and new methods? These are the challenges facing the lithium battery field in the future.
In this situation, many new battery systems such as lithium-sulfur batteries, lithium-air batteries, and sodium-ion batteries have emerged. The continuous production of new materials has also brought new opportunities to the development of these new systems.
Further reading
my country's lithium battery researchers are carrying out a lot of original work
Countries such as China, the United States, Japan, South Korea, Germany, and the United Kingdom have formulated their own battery development strategies in order to promote the innovation of battery principles and the development of core technologies to support the sustainable development of contemporary society. With the support of the state and society, my country's lithium battery researchers continue to carry out scientific research around the unchanging "initial heart" of high-efficiency energy storage.
At present, the mainstream research direction in the field of lithium batteries is still focusing on finding safer and more efficient anode materials. The Tsinghua University research team led by the author has carried out original scientific research in the fields of lithium metal negative electrode nucleation and dendrite-free growth since 2013.
Studies have found that adding a lithium-philic nitrogen-doped carbon skeleton to the lithium metal negative electrode allows free lithium ions in the battery to start charging, just like a tadpole looking for a mother, and preferentially rush to the frog mother-the nitrogen-doped site. A "small group" of evenly distributed lithium metal is formed in the battery; during the charging process, the "small group" of "tadpoles and mother frogs" continues to "hug together." This uniform deposition behavior can avoid the dendritic growth of metallic lithium that has been caused by less nucleation in the past.
The paper based on the above results was selected as the cover of the top chemistry journal "German Applied Chemistry" in 2017. This year, it was also selected for the "Beijing Area Popular Academic Papers" selection activity sponsored by the Beijing Science and Technology Association. Based on the above-mentioned energy chemical mechanism, the research team further designed a carbon-lithium composite anode. These composite metal lithium anodes not only avoid "dangerous dendrites", but also exhibit excellent electrochemical performance, which effectively improves the utilization efficiency and safety of metal lithium anodes, and also provides secondary batteries based on metal lithium. New practical exploration ideas and broader application prospects.
In addition to lithium batteries, the use of sodium, potassium, aluminum, and zinc plasmas and the development of new principles of energy chemistry are also expected to propose new energy storage devices with unique properties. In addition to electrochemical energy storage, the use of other energy storage and conversion methods and new energy carriers is expected to build a disruptive energy storage technology to meet the new needs of the society for energy storage equipment in the future.
