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How the UK's neutron and muon research facility ISIS helps battery technology charge ahead

On October 9, the 2019 Nobel Prize for chemistry was awarded to three scientists for their work in developing the technology upon which much of our modern world relies: the lithium ion (Li-ion) battery. The award celebrated the work of John B Goonenough of the University of Texas at Austin, Akira Yoshino of Meijo University, and M Stanley Whittingham of Binghamton University. What you may not know is that the UK’s ISIS Neutron and Muon Source (ISIS) has been at the heart of many of the advances of this innovative battery technology.

Batteries are made up of one or more cells, each of which contains a positive electrode (anode), a negative electrode (cathode) and, sandwiched between them, an electrolyte that serves as a catalyst to make the battery conductive by promoting the chemical reaction that creates a flow of ions (charged particles) and electrons between the cathode and the anode. When a device is turned on, a stream of positive ions flows across the cell and a stream of negative electrons flow through the electrical circuits.

In a non-rechargeable battery, the chemical reactions only work in one direction – with chemical energy being turned into electrical energy – and when the battery is dead, it is completely dead and must be thrown away (well, responsibly recycled). Rechargeable batteries rely on different chemical reactions that can be reversed so that electrical energy can turned back into chemical energy and stored.

The key to making the most of the existing and emerging technologies upon which we increasingly rely is the development of ever better rechargeable battery technology. Around the world scientists are hard at work investigating which reversible reactions make the best performing batteries. We need batteries that are reliable, hold the most charge and are fast to recharge, but are as lightweight and compact as possible. But while trying to squeeze these qualities in ever-smaller packages, we have to ensure batteries are as affordable and safe as possible.

Bearing in mind that we are talking about tiny devices that contain highly-reactive chemicals in which strong chemical reactions take place, if scientists get the balance wrong, the results can be disastrous. The element at the heart of Li-ion batteries, lithium, is highly-reactive (which is good for generating energy) and highly-flammable (which is bad for something we all carry in our pockets). In 2013, the new Boeing 787 Dreamliner aircraft was grounded just weeks after delivery due to an issue with their Li-ion batteries catching fire and, in 2016, Samsung had to recall their Galaxy Note 7 tablets for the same reason.

All this makes it essential that scientists understand the exact processes and reactions that take place within new battery technology, which is where ISIS comes in. Because neutrons can see light atoms in the presence of heavier ones, they are great for studying small atoms such as lithium. Muons can be used to study how electrical charges move through materials – making ISIS the ideal tool to study the properties of battery technology. Throughout the history of the development of the Li-ion battery, ISIS has hosted many of the research groups who have investigated the properties of the materials used in the batteries – knowledge that has then been applied to improve the battery technology that benefits our lives every day.

A brief history of ISIS and the battery

1990: Experiments using the High Resolution Powder Diffractometer (HRPD) at ISIS gave scientists detailed information about the structure of materials that were being proposed as electrodes in Li-ion batteries. The results showed that the batteries were only rechargeable when the material had a certain layered structure, called a spinel. Since then, materials with this structure have been widely used as cathode materials in rechargeable Li-ion batteries.

2011: Studies using the Polaris beamline investigated the properties of lithium nitride, which had been gaining attention as being the fastest conductor of lithium ions. The studies were able to reveal more information about the structure of lithium copper nitride battery materials and how lithium ions move through it.

2014: A research group from Italy came to ISIS to study a possible material for use as an anode in Li-ion batteries. Also in 2014, another team used muon spectroscopy to investigate the effectiveness of a new, much faster method they had developed to create cathode materials, which used microwaves to synthesise the material in just 15 minutes (prior to this, it had required several days of heating within a furnace).

2016: After it was discovered that the family of minerals known as perovskites might be excellent conductors of lithium ions, ISIS was able to meet the demand to investigate their structures. A testing cell was developed on the Polaris beamline to study these kinds of material.

That same year, using neutron diffraction experiments on Polaris, scientists were able to develop a simple and innovative method for producing a lithium-rich metal oxide that could be used as a cathode. The capacity of Li-ion batteries to store energy is mainly limited by the cathode, so this sort of advance is essential for the development of the next generation of Li-ion batteries that will needed to power electric vehicles.

The present and looking forward

In September 2019, it was announced that scientists and engineers from ISIS would be involved in two of the five projects to win part of £55 million of UK funding from the Faraday Institute – FutureCat and NEXGENNA. The Faraday Battery Challenge is designed to encourage advancements in the field of battery technology.

The FutureCat project is led by the University of Sheffield and involves scientists from ISIS, University of Cambridge, University College London, Lancaster University, and University of Oxford. The project aims to achieve a coordinated approach to developing new cathode technology that hold more charge, are better suited to prolonged recharging, and increase the range and acceleration of electric vehicles.

The NEXGENNA project is led by the University of St Andrews and involves ISIS scientists, Diamond Light Source, five industrial partners, and five international research institutions. The goal is to accelerate the development of sodium ion battery technology, which has the potential for the next generation of long cycle life (the number of times it can be recharged) low-cost, high-performance batteries.

Among the many upcoming battery investigations scheduled at ISIS, the next involves a group that will be investigating the potential to replace the volatile and potential hazardous liquid electrolytes used in existing batteries for solid electrolytes. Little is known about solid electrolytes and how ions move within them so the upcoming study will use muons to investigate this. One of the biggest potential advantages to solid electrolytes over their liquid counterparts would be significant reduction of their potential to burst into flames.

With the help of ISIS, the future is bright for battery technology.


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Last updated: 29 October 2019

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