As the Exxon researchers began to investigate tantalum disulfides, they learned that they could control the temperature in which the layered material assumed superconducting properties by adding – or intercalating – different atoms or molecules between the layers. Potassium ions had the greatest effect. They created a very stable, especially energy-rich compound. The intercalating ions in the tantalum disulfide matrix released a few volts of power, which exceeded the performance of the batteries known at the time. This discovery suddenly put the focus on powerful energy storage.

After testing additional compounds, Whittingham ultimately chose lithium as the electron source for the anode of his battery. The alkali metal is extremely reactive and easily releases electrons to binding partners, but is less dangerous than potassium. He replaced the heavy tantalum disulfide at the cathode, the positive electrode, with lighter titanium disulfide.

This resulted in the first prototype of a lithium-ion battery: a rechargeable battery that could produce a little more than two volts. When Whittingham presented the new lithium battery at the corporate headquarters in New York, it was decided within 15 minutes to develop a commercially viable product.

Although other companies such as General Motors, Sohio, or the U.S. Argonne National Laboratory were researching lithium-based batteries at the same time, Whittingham’s prototype was the only one to function at room temperature.

There were still a few problems to resolve. Thin whiskers of lithium grew at the lithium electrode in repeated charging cycles. When they reached the other electrode, battery short-circuits occurred, followed by what chemists politely describe as “thermal runaway”: an explosion. In fact, the fire department had to put out so many fires in Whittingham’s laboratory that it threatened to make him pay for the expensive special chemicals needed to extinguish lithium fires.

It never came to that. The researchers added aluminum to the metallic lithium electrode and replaced the electrolyte – the liquid between the two electrodes – to gradually resolve the problem. The first batteries were sold in 1976 to a Swiss clockmaker that wanted to use it in solar-powered clocks.

The end of the oil crisis in the early 1980s ultimately brought the era of Exxon’s battery research to a halt. Oil prices fell dramatically and moved the vision of electromobility far into the future. Exxon lost interest in Whittingham’s work and licensed the technology to three different companies in three parts of the world.

The next development step was taken by the second prize winner, John Goodenough, born in 1922 in the Thuringian town of Jena, son of a US professor, who grew up near New Haven, Connecticut. In his youth, the American researcher could hardly imagine that he would go on to receive the Nobel Prize one day. “I couldn’t read very well. I’m still not a very good reader,” he recently said in an interview.

As a young man, Goodenough felt drawn to the world of mathematics and chose to study physics, enrolling at the age of 24, at the end of his WWII military service. “The [university] registration officer said to me, ‘Don’t you know that anybody who had done anything interesting in physics had done it by the time he was your age? And you want to begin?’” Goodenough did – and went on to become one of the best solid material physicists ever.

He worked at the Lincoln Laboratory of the Massachusetts Institute of Technology (MIT) for several decades, where he created the fundamental prerequisites for the development of computer memory. In the wake of oil crises, he became increasingly interested in energy research. In 1976, he transferred to the British Oxford University as a professor for inorganic chemistry to fully concentrate on the topic.

At this time, Goodenough was already familiar with Whittingham’s battery. His specialized knowledge in material science told him that its cathode could have a higher potential if it was built using an oxide instead of titanium disulfide. Together with his team, he began to search for a suitable material. It had to produce high voltage with intercalating lithium ions, yet had to be stable enough not to collapse when the ions were removed. The researchers ultimately found what they were looking for in lithium cobalt oxide. The battery generated four volts instead of two – double the potential of Whittingham’s model. Goodenough first described the new concept in a technical journal in 1980. The U.S. scientist was the first to realize that batteries did not have to be manufactured in their charged state, as had been the practice previously. Instead, they could be charged after their assembly.

While interest in alternative energy technology declined in the West in the early 1980s at the end of the oil crises, things were different in Asia, where emerging electronics companies had great hopes for powerful, lightweight batteries. They saw them as a crucial component to turn camcorders, mobile phones, and laptops into bestsellers.

Akira Yoshino, who worked as an engineer at the Japanese electronics company Asahi Kasei, recognized the new possibilities. “I just sort of sniffed out the direction that trends were moving,” the Nobel Prize winner later noted.

Yoshino was born in 1948 and grew up in Osaka, Japan’s second largest city. His interest in chemistry dated back to a teacher in fourth grade, who introduced him to the book “The Chemical History of a Candle,” a collection of lectures by the British chemist Michael Faraday from the 19th century. Yoshino read the book and was excited: “Why do candles burn? Why are the flames yellow? What are the wicks for? I thought this seems kind of fun,” he recalled at a press conference decades later.

After graduating from the University of Kyoto, Yoshino started researching a material called polyacetylene at Asahi Kasei. Although it is an organic substance, it conducts electricity. Yoshino was looking for a way to use polyacetylene as an anode in a battery, but was unable to find a suitable material for the cathode.

In 1983, he came across a technical article that discussed Goodenough’s lithium cobalt oxide as a cathode material. Decades later, Yoshino recounted that the idea that would later lead to the development of lithium-ion batteries came to him during one of his free afternoons, after cleaning up his laboratory.

Instead of using polyacetylene, he built an anode on the basis of petroleum coke, a carbon byproduct of the oil industry. The special advantage of the material is based on its structure: Lithium ions can intercalate in petroleum coke without changing it. This last step established the basic structure of the world’s first commercially viable lithium-ion battery. With one electrode made of petroleum coke and the other, of lithium cobalt oxide, the battery no longer contained any metallic lithium – a crucial safety gain. Sony launched the first batteries in 1991.

That event marked the end of the research work on lithium-ion batteries, for which Whittingham, Goodenough and Yoshino were recognized with the Nobel Prize in Chemistry in 2019. However, the development of the battery itself was by no means complete. To this day, the three Nobel Prize winners keep researching improvements, such as new electrode materials or design principles.

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