The Science Behind The Lithium-Ion Battery Research That Won 2019’s Nobel Prize In Chemistry

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Although initially set up to recognize the most beneficial contributions to humankind, it is not every year that a Nobel Prize winning discovery has had such widespread impact. Look at it this way: most people reading today’s news about the Nobel Prize in Chemistry did so on a device that has directly benefited from the research. In what for many seemed a long overdue acknowledgment, today’s Prize was awarded to three scientists for their work on developing lithium ion batteries; the very same batteries that power our phones, laptops, electric vehicles and so much more.

John B. Goodenough of The University of Texas at Austin, USA, M. Stanley Whittingham of Binghamton University, State University of New York, USA and Akira Yoshino of the Asahi Kasei Corporation, Tokyo, Japan, each share a third of the prize, but what makes these batteries so special, and how do they work?

Many of us grew up hunting the house for batteries on Boxing Day to keep our new toys going. At a basic level, these so called alkaline batteries, owing to their potassium hydroxide content, have similar features to these Nobel Prize-winning Li-ion batteries; they both have two electrodes (a zinc anode as a negative terminal, and a manganese oxide cathode as a positive terminal) separated by an electrolyte. However, the reaction that takes place in a regular alkaline battery cannot be reversed, and so they cannot be recharged, unlike a Li-ion battery. There is also a huge difference in their voltage, which is the difference in electrical charge between their electrodes, with alkaline batteries plateauing at 1.5 V compared to the higher voltage of Li-ion. A higher voltage results in a steeper gradient between areas of electrical charge and therefore a faster flow of electrons, or a higher current, when the circuit is complete, which is favorable in applications with a higher energy demand.

Development of better batteries that led to today’s Nobel Prize started back in the 1970s, when Whittingham created a novel cathode from titanium disulfide, a layered material. The layers of this material are stacked a little like the trays returned to an Ikea café clear-up area. Within these layers, lithium ions can reside, like the discarded Ikea coffee mugs ready to be washed and used once more. The corresponding anode that Whittingham created contained some lithium metal which, as you may remember from high school chemistry demonstrations, is very reactive. While this battery had a potential difference of 2 V, a third better than an alkaline battery, the explosive nature of the lithium made them impossible to use in many applications. The metallic lithium also had a tendency to grow needle-like whiskers, or dentrites, which over time could bridge the gap between the two electrodes, causing the battery to short-circuit.

In a perfect example of taking someone’s potential failure and using it as a stepping stone to success, Goodenough’s electrochemistry calculations led him to ponder whether using a metal oxide in place of the titanium disulfide cathode would result in an even greater potential difference between the two electrodes. A decade after Whittingham’s groundbreaking work, Goodenough successfully demonstrated his progress. By using cobalt oxide as the layered material safely housing the lithium ions, he doubled the potential difference of the batteries to a whopping 4 V.

Crossing the bridge between science and engineering, Yoshino tackled the potential problem of using highly reactive lithium in the anode. He replaced it with petroleum coke, a material that he had been researching and that he found to have naturally occurring layers within its structure and high enough stability to work within the conditions required by such a battery. These layers could also house lithium ions, just like the corresponding cobalt oxide cathode on the other side of the battery. In doing so, in 1985 he created the first safe Li-ion batteries. These became commercially available in 1991, and heralded a new age of technological applications in devices that required a lot of energy, but also a degree of portability that could not be achieved using previous batteries that were heavy, cumbersome, and could be damaged or explode with the sort of rough handling that we expect our portable devices to withstand today.

Regular batteries rely on reversible chemical reactions that quickly degrade in their capacity over time. In this case, the charge and discharge cycles in Li-ion batteries simply rely on the movement of these lithium ions from one electrode to the other, and back again. There is very little degradation in the system, and therefore very little loss of performance in each cycle of charge and discharge. The layered electrodes allow for a high energy density by packing a high concentration of these lithium ions into each cell. These batteries are also made of lightweight materials. Additionally, their large capacity means that a small, lightweight battery can be used to power an energy-draining object, allowing almost all of us to walk around with exceptionally powerful computers in our pockets with touch-sensitive color screens to watch cat videos on, high specification cameras to take selfies with, and even the capability to contact each other by telephone, should we so wish.

It isn’t just mobile phones and laptops that are powered by these batteries. Electric vehicles are being kitted out with the latest Li-ion batteries that hold a larger charge for longer in a lower material density battery, meaning that we can drive further for longer between charges, making electric cars a truly viable alternative to more polluting cars with petrol engines. It is the interface with clean, renewable, sustainable energy and their ease of electrical charge and discharge that really places these batteries firmly in our clean energy future.

Goodenough, Whittingham and Yoshino become the 25th trio to share the Nobel Prize in Chemistry, in what is a perfect example of scientists discovering the work of others and improving on it to create something truly groundbreaking. They also become the 176th, 177th and 178th men to become Nobel Laureates of Chemistry. While the awards were initially set up to celebrate the greatest achievements in research in the year prior to the award, the trend has on the whole changed to now acknowledge historic research that has resulted in a large impact on life as we know it today. Similarly, most cutting edge research today is carried out by large international collaborations made up of more diverse groups of researchers.

Given that the Nobel Prizes can only be awarded to up to three individuals, it will be interesting to see whether the rules around this change over time to reflect the more open, inclusive and collaborative nature of modern scientific breakthroughs. Perhaps we will even see the sixth ever female Nobel Laureate in Chemistry. I have no doubt that the research of these excellent scientists will inspire many future discoveries, and perhaps even some future Nobel Prize winners too.

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