3D tomographic imagery reveals how lithium batteries age

Tomography of a lithium electrode in its initial condition.

Tomography of a lithium electrode in its initial condition.

</p> <p class="MsoPlainText">Changes are visible after the first charging and discharging cycles.

Changes are visible after the first charging and discharging cycles.

After a longer period of operation, areas form that reduce performance and can cause short-circuits.

After a longer period of operation, areas form that reduce performance and can cause short-circuits. © M. Osenberg / I. Manke / HZB

Lithium batteries lose amp-hour capacity over time. Microstructures can form on the electrodes with each new charge cycle, which further reduces battery capacity. Now an HZB team together with battery researchers from Forschungszentrum Jülich, the University of Munster, and partners in China have documented the degradation process of lithium electrodes in detail for the first time. They achieved this with the aid of a 3D tomography process using synchrotron radiation at BESSY II (HZB) as well at the Helmholtz-Zentrum Geesthacht (HZG). Their results have been published open access in the scientific journal "Materials Today".

Whether electric mobility, robotics, or IT - lithium batteries are simply used everywhere. Despite decades of improvements, it has not yet been possible to prevent such batteries from "ageing". Amp-hour capacity is lost with every charge cycle. The processes that lead to this are roughly understood. Now an international team headed by HZB researcher Dr. Ingo Manke has been able to observe with microscopic precision exactly what happens inside the battery at the interfaces between the electrodes during migration of the lithium ions.

3D insights into lithium cells

Manke is an expert in 3D synchrotron tomography, a method that utilises particularly intense X-rays. 3D images can be created of the interior of samples using this non-destructive imaging method with particularly high precision that is available on the BAM beamline at BESSY II. His team investigated a number of different lithium cells during charging and discharging under different cycle conditions. All cells studied had one side of the electrode made of pure lithium, while the other side was constructed of a selection of different electrode materials. Part of the investigation also took place at the Helmholtz-Zentrum Geesthacht.

Formation of microstructures

The tomographic imagery shows how a layer forms between the separator layer and the lithium electrode characterised by microscopic features after only a few charge/discharge cycles. The microscopic features of this layer consist of reaction compounds that form in the electrolyte and can take different forms – from a rather disordered slurry, to moss-like structures, to needle-shaped dendrites that can even cause dangerous short circuits in the battery.

“This gives us for the first time a complete picture of the degradation mechanism in lithium electrodes”, says Manke. It is not only of interest for fundamental understanding of the aging processes in batteries, but also provides valuable directions in the design of more durable batteries.

arö


You might also be interested in

  • Green Deal Ukraina: HZB launches an Energy & Climate Project
    News
    07.06.2023
    Green Deal Ukraina: HZB launches an Energy & Climate Project
    Green Deal Ukraina, funded by the German Federal Ministry of Education and Research, is working with partner institutions in Ukraine and Poland to establish an energy and climate think tank in the capital, Kiev. The aim is to provide independent and evidence-based advice on rebuilding a sustainable energy system in Ukraine. After all, the implementation of energy and climate legislation is a prerequisite for Ukraine's accession to the EU. The project started on 1 June 2023 and will run for four years.
  • Spintronics at BESSY II: Domain walls in magnetic nanowires
    Science Highlight
    02.06.2023
    Spintronics at BESSY II: Domain walls in magnetic nanowires
    Magnetic domains walls are known to be a source of electrical resistance due to the difficulty for transport electron spins to follow their magnetic texture. This phenomenon holds potential for utilization in spintronic devices, where the electrical resistance can vary based on the presence or absence of a domain wall. A particularly intriguing class of materials are half metals such as La2/3Sr1/3MnO3 (LSMO) which present full spin polarization, allowing their exploitation in spintronic devices. Still the resistance of a single domain wall in half metals remained unknown. Now a team from Spain, France and Germany has generated a single domain wall on a LSMO nanowire and measured resistance changes 20 times larger than for a normal ferromagnet such as Cobalt.
  • Fractons as information storage: Not yet quite tangible, but close
    Science Highlight
    26.05.2023
    Fractons as information storage: Not yet quite tangible, but close
    A new quasiparticle with interesting properties has appeared in solid-state physics - but so far only in the theoretical modelling of solids with certain magnetic properties. An international team from HZB and Freie Universität Berlin has now shown that, contrary to expectations, quantum fluctuations do not make the quasiparticle appear more clearly, but rather blur its signature.