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NEWS

June 2021 ESRFnews

ERC grant shakes up earthquake science A long-term ESRF user has been awarded an advanced grant from the European Research Council to study the origins and precursors of earthquakes. François Renard, a geophysicist at the University of Oslo in Norway and the University Grenoble Alpes in France, will undertake the Break-Through Rocks (BREAK) project using a bespoke rock-deformation apparatus in combination with 4D X-ray microtomography and acoustic emission on the new EBS flagship beamline, BM18, as well as measurements at the ID19 and ID11 beamlines. Earthquakes pose big threats to

humans living and working near fault zones. Just a decade ago, a magnitude nine quake off the coast of To¯hoku in Japan generated a huge tsunami that killed nearly 20,000 people and caused hundreds of billions of dollars of damage. Despite much research, however, the time and location of earthquakes is impossible to predict with any accuracy, and big questions remain about their development. For instance, does water weaken or strengthen a fault? How does rock damage propagate? What is the strain at the tip of a rupture? Renard, who has published 25

articles on data acquired at the ESRF beamline ID19 in the past five years, hopes to answer these questions with a suite of ground-breaking experiments. At BM18 the ESRF s new flagship beamline for microtomography that fully exploits the high energy X-rays of the new EBS source he and his colleague Benoît Cordonnier will

install a rock-deformation apparatus, ZEUS, to study the mechanisms that control the transition from slow, aseismic slip to rapid seismic rupture in rock samples. This beamline will provide new capabilities by providing the world s largest high-energy and high-coherence synchrotron beam for hierarchical imaging and high- throughput tomography, he says. The BM18 data will be complemented with ultrafast imaging of shock waves in water-saturated rocks taken at ID19, and X-ray diffraction to deduce strain patterns at ID11. The ESRF has the world-leading capabilities needed to perform our experimental programme, Renard adds. The goal of all the work is to unearth

weak signals that precede dynamic rupture, and determine the time between such signals and rupture. If we can demonstrate that the joint analysis of acoustic-emission signals and X-ray microtomography data can be used to predict dynamic rupture in our experiments, we will have discovered an important lead towards earthquake prediction, says Renard. Harald Reichert, ESRF director of

research, believes that the awarding of the grant is a clear indication of the potential of the ESRF EBS. This is breakthrough research of the highest impact, enabled by the provision of synchrotron X-ray beams with unprecedented brilliance and coherence, he says. The success of the EBS project will be measured by its inspiration of leading scientists such as François Renard to push the frontiers of science with the tools we provide.

Inexpensive battery survives thermal runaway

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A polymer layer recently introduced into certain models of 18650 rechargeable battery to reduce manufacturing costs also helps to prevent thermal runaway, ESRF users have found.

The 18650 cell is commonly used to power laptops, flashlights and electric vehicles. Based on lithium-ion technology, it houses a component known as a current collector to conduct electricity between the negative and positive terminals. Usually, the current collector is made of aluminium or copper. If the battery is damaged, for instance in a car crash, the metal can puncture, short-circuiting the battery. The short-circuit rapidly deposits heat, with temperatures reaching as high as 800 °C, causing fires.

Based at University College London (UCL) in the UK, the National Renewable Energy Laboratory (NREL) and NASA in the US, and the ESRF, the researchers came to the ID19 beamline to study the phenomenon, simulating a typical impact by driving in a nail. They tested both a standard 18650 battery and a new type, the current collector of which had been manufactured in an aluminium-plastic-aluminium tri-layer to reduce costs by 40%. To their surprise, unlike the standard model, the model housing the cheaper, plastic-based current collector did not exhibit a short- circuit after perforation. High-speed synchrotron X-ray radiography at ID19, combined with pre- and post-mortem X-ray computed tomography, showed that the polymer bends with the nail before ultimately tearing. Then, when a short does occur, the polymer bends away from the hot region like plastic wrap held to a flame isolating the short and preventing thermal runaway (Cell Rep. Phys. Sci. 2 100360).

François Renard, the grant winner, is a geophysicist at the University of Oslo in Norway and the University Grenoble Alpes in France.

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Top: A nail easily punctures the standard cell, instigating thermal runaway. Bottom: Thermal runaway is absent in the cell with the new polymer composite layer.

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