When a Nobel Prize in Chemistry honors a battery

It's no coincidence that the 2019 Nobel Prize in Chemistry has been awarded to the pioneers of the lithium-ion battery.

Laure Monconduit, University of Montpellier

Today, this type of battery powers smartphones and laptops, cameras, MP3 players and the vast majority of electric and hybrid vehicles currently on the market, while opening up new horizons in the storage of renewable energies. As Jean-Marie Tarascon, Professor at the Collège de France and holder of the Chemistry of Solids and Energy Chair, recently declared on a television channel, "this is one of the great advances of the last century, along with the transistor and fibre optics".

Three men for a Nobel

Three men were awarded the prize on October 9: Anglo-American Michael Stanley Whittingham, American John Bannister Goodenough and Japanese Akira Yoshino. These three researchers, who are well known to all scientists working in chemistry and the physical chemistry of materials, have been enriching the field of energy storage for over forty years. And, of course, they are the driving force behind numerous advances in the field of lithium-ion batteries.

It all began in the 1970s with the work of chemist M. S. Whittingham. A graduate of Oxford University, where he obtained his bachelor's, master's and doctorate degrees, he went on to do a post-doctorate at Stanford University before joining Exxon Research and Engineering in 1972. There, for 16 years, he worked on the development of non-fossil fuel energy sources. He then joined Schlumberger, before being appointed Professor at Binghamton University in 1988.

Starting with research into so-called superconducting materials, he discovered a particularly interesting one: titanium disulfide (_TiS2). As early as 1965, German chemist Walter Rüdorff had demonstrated the possibility of intercalating lithium ions (Li+) in solution in _TiS2. However, the French chemist Jean Rouxel, then M. S. Whittingham himself and his Exxon colleague, the American Fred R. Gamble, subsequently proved that it was possible to intercalate more lithium into titanium disulfide than Rüdorff had done, without altering the crystallographic structure of the material too much.

In fact, as early as 1973, M.S. Whittingham had discovered that intercalating lithium in an electrochemical cell was a reversible phenomenon. Titanium disulfide, with its lamellar structure, could therefore be the material of choice for a rechargeable lithium battery. The principle is as follows: lithium ions, released by an anode (negative electrode) consisting of lithium in metal form, are stored at the cathode (positive electrode) between the layers of titanium disulfide. The first rechargeable lithium battery was born, with a potential in excess of 2 volts.

A new material: cobalt oxide

J.B. Goodenough, an American, obtained his doctorate in physics in 1952 from the University of Chicago. Initially a researcher at the Massachusetts Institute of Technology (MIT) laboratory, he and his team worked on computer random access memory, also known as magnetic random access memory. He then took charge of the inorganic chemistry laboratory at Oxford University, where he developed a material for the cathode of the rechargeable lithium-ion battery(cobalt oxide), before joining the University of Texas at Austin in 1986, in the mechanical and electrical engineering departments of the Cockrell School of Engineering: he remains very active there to this day, having recently published with his team some very promising results for a battery in which the electrolyte would be solid, offering a gain in terms of safety.

His work on cobalt oxide, as a replacement for titanium disulfide, paved the way for batteries capable of delivering a voltage of 4 volts. This cathode material is now used in virtually all commercial batteries. However, this battery, which uses a lithium metal anode, proved to be too dangerous, with the risk of lithium dendrites forming, which could bring the cathode and anode into contact, causing short-circuits and even an explosion. It was therefore quickly withdrawn from the market.

The first lithium-ion battery on the market

The last of the three Nobel Prize-winning researchers in chemistry, Akira Yoshino originally graduated from Kyoto University in 1972 with a master's degree in engineering, before devoting a few years to archaeology. But he returned to his first love, earning a doctorate in engineering from Osaka University in 2005. In 1986, he developed the first commercially viable lithium-ion battery, in which the overly reactive lithium anode was replaced by a carbon-based anode (petroleum coke), into which lithium ions could be inserted.

Replacing Lithium metal with carbon has extended battery life and improved safety. But, above all, it was the essential step on the road to market launch. Sony was the first to market this technology in 1991, using lithium cobalt dioxide as the cathode and carbon as the anode. Many other companies followed, including Toyota, LG, Samsung, Panasonic and others.

At a time when a veritable battery race is underway the world over, the 2019 Nobel Prize in Chemistry highlights the importance of research in the field of energy storage. This research is all the more important given the need to store energy "cleanly", without recourse to fossil fuels, and thus combat global warming.

Laure Monconduit, Researcher - DR1, AIME Team, University of Montpellier

This article is republished from The Conversation under a Creative Commons license. Read theoriginal article.