How chemistry Nobelist Akira Yoshino bucked conventional wisdom to develop the lithium-ion battery

The 2019 Nobel Prize in Chemistry went to three researchers who developed the lithium-ion battery. One of the three, Akira Yoshino, honorary fellow at the Japanese chemical company Asahi Kasei, was not trying to discover a new battery. “I didn’t know about conventional wisdom in the field of battery technology,” Yoshino recalls. His lack of expertise, he believes, is precisely what made his research breakthrough possible. “Doubt conventional wisdom” was a motto of professor Kenichi Fukui at Kyoto University, an earlier chemistry Nobel Prize winner under whom Yoshino studied.

Yoshino is the eighth Japanese scholar to win a chemistry Nobel Prize but only the second from the country who hails from industry. He began researching polyacetylene as a battery material in 1981 and created the first commercially viable lithium-ion battery in 1985.

Katsumori Matsuoka interviewed Yoshino for C&EN at the Tokyo headquarters of Asahi Kasei soon after he won the prize. They talked about the lack of recognition of industrial chemists’ accomplishments, what Yoshino’s research has brought to Asahi Kasei, and future research themes.

What conventional wisdom did you challenge in pioneering the use of carbon materials for the lithium-ion battery anode?

The spirit of “doubt conventional wisdom” was reflected most obviously in the development of the anode material because if I were with a battery manufacturer, I never would have engaged in the development of lithium-ion batteries with a carbon-based anode.

In those days, the battery industry was intent on pioneering a new type of rechargeable battery, but it faced rough going. It couldn’t commercialize the product because it couldn’t find a good anode material. Lithium metal was attempted, but its high reactivity posed safety problems.

I began to use polyacetylene as an anode because lithium ions go in and out of it. It lacks common sense to dare to use such a material because it increases the weight and volume of the anode. But using polyacetylene, and later carbon, as the anode material helped solve the safety problems and realize commercial lithium-ion batteries.

After you discovered that carbon could be used as an anode material, Asahi allowed you to push your research into top gear to develop a new product. But you hit a wall. How did you overcome the challenge?

The biggest hurdle was finding a good cathode material to pair with a carbon-based anode. When a cathode and an anode are paired up, both must be either in the discharged state or the charged state. In primary cell [disposable] batteries, all cathodes and anodes used in those days were in the charged state. Polyacetylene- and carbon-based anodes are in the discharged state. Therefore, the corresponding cathode material must be in the discharged state. However, we had no material to be paired with carbon. With excellent timing, John Goodenough [who won the chemistry Nobel together with Yoshino and M. Stanley Whittingham] developed a new cathode material that contains lithium and is in the discharged state.

You helped develop many materials used in lithium-ion batteries, including electrodes, electrolytes, and separator films, but today Asahi Kasei is only in the battery separator business. Why is that?

Our company originally intended to apply polyacetylene to batteries, thus marketing polyacetylene. This is a straightforward idea for a chemical corporation. While we were test producing batteries, we needed to develop electrolyte and cathode materials as well as separators.

Consequently, the separator business developed greatly. We did produce lithium-ion batteries on a commercial basis through a joint venture, A&T Battery, with Toshiba from 1992 through 2000. Asahi Kasei, however, handed over its shares to Toshiba in 2000, withdrawing from the battery business.

It is advantageous that a corporate research umbrella includes relationships between a user [a maker of lithium-ion batteries] and a supplier [of its components]. They can exchange firsthand data. In this context, A&T provided great support to the separator business because we had connections with a battery manufacturer who actually used the separators.

What are some of the tricks you have used to manage research effectively without too much corporate interference?

In 1981, our research staff was three people at most. I managed in those days to neither employ much staff nor spend much money. When trying to do everything by ourselves, budgets tend to swell, attracting higher-ups’ attention. For example, a coating machine to produce an electrode on a trial basis cost as much as ¥50 million [about $500,000]. Therefore, I outsourced trial manufacturing at a lower cost. I tried hard not to increase staff members and swell research budgets.

You are only the second Japanese chemistry Nobelist from industry, after Koichi Tanaka of Shimadzu. The other six are from academia. Is it difficult to stand out when you are from industry?

In June of 2019, I received the European Inventor Award from the European Patent Office [EPO], an award that greatly aided my winning of the Nobel Prize as a corporate researcher. Academic papers don’t have great significance for industry. Goodenough wrote a paper on the use of new cathode materials, but researchers in industrial sectors wouldn’t publish this. Instead, they would apply for patents. Patent applications are, however, usually written in an incomprehensible style. Even if the same research results are contained in academic papers and patents, the latter are at a disadvantage. As a result, industrial circles are handicapped with regards to the Nobel Prize. The award from the EPO seems to have offset the handicap.

How is your relationship with John Goodenough?

We didn’t collaborate on research activities. However, we have had friendly relations for a long period of time. I usually visit his house in Texas every year. Owing to the age difference [Goodenough is 97 and Yoshino is 71], it is sort of like a parent-and-child relationship. We first met in person in 2000, after I won an award from the Electrochemical Society of the US. He hastened to my memorial lecture held in Hawaii. He came all the way from Texas to Hawaii for it.

What research lies ahead for the lithium-ion battery field?

The use of lithium-ion batteries in mobile computing has come close to its ideal form, but it will take 5 more years to realize automobile applications in their ideal form.

Also, the solid-state battery has aspects that can’t be explained using traditional textbooks on batteries. We can partially explain some of them with the semiconductor industry’s concept of positive holes. It may be possible to build on this concept to pioneer an innovative solid-state battery that is fundamentally different from today’s liquid-electrolyte batteries.

We need to promote research on solid-state electrolytes irrespective of whether an all-solid-state battery is put into practical use. If the movements of lithium ions are elucidated, we could make them move much more quickly in an electrolyte now in use and design an appropriate cathode material.

What message do you have for young researchers?

Many unknown aspects still remain in science, including chemistry. The natural world is deep. Environmental problems provide the greatest challenges, a chance to become world heroes. Young researchers should see them as a great opportunity.

Katsumori Matsuoka is a freelance writer based in Japan. He was assisted by translator Masayuki Ikeda. This interview was edited for length and clarity.