#EBSstories From Oslo to Grenoble in the search of next generation batteries

01-09-2021

Silicon has ten times higher capacity than the anode materials used in today’s lithium-ion batteries, but it cannot cycle many times. A team from the University of Oslo is trying to understand why on ID15A.

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“Arriving at the ESRF has been an epic journey”, explains David Wragg, scientist at the University of Oslo. He and his colleague, Anders Brennhagen, have travelled more than 2000 kilometers by sea and land to get their precious samples to the ESRF: lithium-ion batteries that use silicon to increase capacity.

Lithium-ion batteries are the power source of choice for portable devices and electric vehicles because of their high energy densities, long cycle life and affordable cost.

Battery producers are striving to increase the driving range of electric vehicles. Alloying anodes are one of the most promising new technologies, and may enable major improvements to lithium-ion batteries. By alloying multiple Lithium ions with each atom in the anode, very high capacities are reached.

Silicon anodes have up to 10 times more capacity than graphite- giving two to three times greater capacity in the battery overall. Unfortunately, the material doesn’t cycle very well. “So you’d be able to drive your electric car much further than with graphite, but you’d only be able to do that two or three times until the battery would stop working”, says Wragg. Silicon lithium-ion batteries anodes are being commercialised, but their fundamental mechanism of activity is not fully understood despite several studies.

Now the team from the University of Oslo are on ID15A to explore the structural and electrochemical behaviour of silicon anodes for next-generation lithium-ion batteries. “On the beamline, we use operando X-ray diffraction and PDF computed tomography techniques to compare the structural changes while charging and discharging the battery, with the aim of fully revealing the mechanism of activity”, explains Wragg.

EBS has been a game changer for the team: “With EBS we can get much more detailed information about the fast processes of charging and discharging a battery. We can also get better information about what is going on in different parts of the battery, because we can focus the beam to smaller sizes.”

The samples studied come from the Norwegian Research Center on Zero Emission Energy Systems for Transport (MoZEES), a collaboration between Norwegian academia and industry.

Text by Montserrat Capellas Espuny.

Video by Montserrat Capellas Espuny and Mark McGee