Under the supervision of Ryoji Kanno, an Institute Professor at the Tokyo Institute of Technology who has been involved in improving battery performance for more than 30 years, this series of articles explores lithium-ion batteries, from what they are to the status of research into the solid-state batteries called the next-generation lithium-ion batteries. Part 3 introduces the history of research to make lithium-ion batteries practical and why lithium-ion batteries have become as popular as they have.
Supervisor: Ryoji Kanno
Institute Professor (Professor Emeritus), Institute of Innovative Research, Tokyo Institute of Technology
In 1980, he completed his master’s degree in inorganic and physical chemistry at the Graduate School of Science, Osaka University. In 1985, he became a Doctor of Science. After working as an associate professor in the Faculty of Science at Kobe University, he became a professor at the Tokyo Institute of Technology Interdisciplinary Graduate School of Science and Engineering in 2001. In 2016, he became a professor at the Tokyo Institute of Technology School of Materials and Chemical Technology. In 2018, he became a professor at the Tokyo Institute of Technology Institute of Innovative Research and a leader in the All-Solid-State Battery Unit. In 2021, he became an Institute Professor at the Tokyo Institute of Technology Institute of Innovative Research and director of the Research Center for All-Solid-State Battery.
1. Nobel Prize for lithium-ion batteries
The 2019 Nobel Prize in Chemistry was awarded to three researchers who contributed to the development of lithium-ion batteries: engineer Akira Yoshino, physicist John Goodenough, and chemist Stanley Whittingham. Why have lithium-ion batteries attracted so much attention from around the world that they merited a Nobel Prize?
The reason for this is that the practical application of lithium-ion batteries has an important meaning not only in the history of batteries but also in the history of humankind. If a small and lightweight secondary battery, such as lithium-ion batteries, had not been put into practical use, the smartphones and PCs everyone uses now may never have become as small as they are. The distance that electric vehicles could run on a single charge would have been shorter, and the prospect of their practical application may not have been possible. Moreover, new tools such as drones, which are now expected to play an active role not only in video shooting but also in various fields such as patrolling from the skies and transportation of goods, may never have been created.
With compactness and weight reduction that was too difficult to achieve with lead-acid batteries, nickel-cadmium batteries, and nickel-metal hydride batteries, lithium-ion batteries made possible such a variety of tools as to change the structure of society. A Nobel Prize was awarded to the three researchers not only for the invention of a battery, but in recognition of such social contribution.
In fact, even before receiving the Nobel Prize, lithium-ion batteries were awarded the Charles Stark Draper Prize, which is said to be the Nobel Prize of engineering, in 2014. John Goodenough, Yoshio Nishi, Rachid Yazami, and Akira Yoshino were presented with the award for their achievements in the spread of lithium-ion batteries and the development of their basic structure.
2. History of lithium-ion batteries
How did lithium-ion batteries, such a major invention that they will go down in human history, come about?
The technology to make use of lithium in batteries was proposed in 1976 by Whittingham, then an engineer at an American oil company. At that time, titanium disulfide was used as the cathode material, and lithium was used as the anode material. However, batteries combining titanium disulfide and lithium did not work stably as secondary batteries. So, lithium batteries were put to practical use as primary batteries that cannot be recharged, such as batteries for floats used in fishing and to power flashes in disposable cameras.
In 1980, Goodenough, who was researching lithium batteries at the time, proposed the use of lithium cobalt oxide as the cathode material. The following year, Yoshino proposed a method of combining carbon as the anode with the cathode of lithium cobalt oxide.
Then, in 1983, Goodenough proved that inexpensive lithium manganese oxide could also be used as the cathode material, and Yoshino established a technology to stably exchange ions between the cathode and anode. Thus, the prospect of putting lithium-ion batteries to practical use as secondary batteries was established.
In the 1990s, lithium-ion batteries used in consumer products such as mobile phones and laptops were launched. At first, they were used in the field of mobile phones, and after that, their use spread widely to portable audio and laptops. This happened because the required voltage decreased with the reduction in size of the main units, with the voltage required going from 5.5V to 3V. As a result, it was judged to be more efficient to use a single lithium-ion battery that can produce a voltage of 3V rather than using three nickel-cadmium batteries that can only produce voltages up to 1.25V.
Following the shift to mobile IT-related products in the 1990s, the environment and energy revolution since 2006 has led to the growing need for electric vehicles. With performance suitable as secondary batteries for automobiles, such as high voltage and energy density, lithium-ion batteries went on to be used in electric vehicle-related applications.
In this way, lithium-ion batteries have been actively adopted for various products, and with the increase in the number of units produced, costs have come down, and the range of their applications has expanded.
3. Battery lifespan supporting the spread of lithium-ion batteries
The range of applications of lithium-ion batteries expanded so much because they have a longer life than other secondary batteries. How much longer do lithium-ion batteries last than other batteries?
There are several factors that determine the lifespan of a battery. Since lithium-ion batteries use a slightly different reaction from the battery reaction that occurs in other secondary batteries when extracting electricity, the electrodes deteriorate little. The fact that they hold up well to repeated charging and discharging and are resistant to natural discharge are also factors that extend their lifespan.
Two different numbers are used to express battery lifespan as a number: cycle life and calendar life. Cycle life refers to the number of times that a battery can go through the cycle of starting discharged to the limit with 0% charge, being charged up to 100%, and then being discharged back to a state of 0% charge. Calendar life refers to the period of time during which batteries can be used even if left in inactive storage at a certain state of charge.
It is not possible to generalize about these figures expressing lifespan because they depend on a variety of factors such as the battery manufacturer and product, the environment and conditions of use, and the terms and conditions of maintenance. For example, referring to the data in the “Storage Battery Strategy” released by the Japanese Ministry of Economy, Trade and Industry, lead-acid batteries have a cycle life of up to 3,150 cycles and a calendar life of 17 years, nickel-metal hydride batteries have a cycle life of up to 2,000 cycles and a calendar life of 5 to 7 years, and lithium-ion batteries have a cycle life of up to 3,500 cycles and a calendar life of 6 to 10 years.
Looking at these figures, lead-acid batteries have a longer life than lithium-ion batteries; but lead-acid batteries are large and heavy, as you can see by looking at what is loaded in cars, so they cannot be compared to lithium-ion batteries from the viewpoint of size and weight.
|Nickel-metal hydride batteries
|5 to 7 years
|6 to 10 years
Comparison of the lifespan of lead-acid batteries, nickel-metal hydride batteries, and lithium-ion batteries
4. Evolving lithium-ion batteries
The basic configuration of lithium-ion batteries has not changed significantly since Akira Yoshino established the technology to stably exchange ions between the cathode and anode in 1983, but improvements have been made in such things as the materials, the amount of electricity stored, and weight.
The material used for the cathode has changed from the cobalt-based lithium proposed by John Goodenough in 1980 to materials such as manganese, nickel, and iron, resulting in cost reductions and changes in cycle life. In addition to materials, improvements have been made in every part of lithium-ion batteries, such as packing as much material as possible into the batteries so as to store as much electricity as possible, and changing the case into which the battery material is packed from stainless steel to laminate to reduce weight.
In this way, batteries have evolved through the accumulation of such efforts by researchers and the evolution of technology. The next article examines “solid-state batteries,” which are said to be promising candidates as the next-generation batteries.
- Part 5: How do lithium-ion batteries contribute to the realization of a sustainable society? A look at the benefits of replacing lead-acid batteries, recycling methods, and the possibilities for the future
- Part 4: What are solid-state batteries? An expert explains the basics, how they differ from conventional batteries, and the possibility of practical application.
- Part 2: What are the advantages of lithium-ion batteries and what considerations apply when charging them? Find out why they have various uses, from smartphones to cars.