User research at BESSY II: Graphite electrodes for rechargeable batteries investigated
The tomogram during the charging process shows the spatially resolved changes in the graphite electrode thickness of a rechargeable aluminium ion battery in a discharged and charged state. © HZB
Rechargeable graphite dual ion batteries are inexpensive and powerful. A team of the Technical University of Berlin has investigated at the EDDI Beamline of BESSY II how the morphology of the graphite electrodes changes reversibly during cycling (operando). The 3D X-ray tomography images combined with simultaneous diffraction now allow a precise evaluation of the processes, especially of changes in the volume of the electrodes. This can help to further optimise graphite electrodes.
Published in Advanced Functional Materials (2020); Simultaneous X‐Ray Diffraction and Tomography Operando Investigation of Aluminum/Graphite Batteries; Giuseppe Antonio Elia, Giorgia Greco, Paul Hans Kamm, Francisco García‐Moreno, Simone Raoux, Robert Hahn
DOI: 10.1002/adfm.202003913
Abstract: Rechargeable graphite dual‐ion batteries are extremely appealing for grid‐level stationary storage of electricity, thanks to the low‐cost and high‐performance metrics, such as high‐power density, energy efficiency, long cycling life, and good energy density. An in‐depth understanding of the anion intercalation mechanism in graphite is fundamental for the design of highly efficient systems. In this work, a comparison is presented between pyrolytic (PG) and natural (NG) graphite as positive electrode materials in rechargeable aluminum batteries, employing an ionic liquid electrolyte. The two systems are characterized by operando synchrotron energy‐dispersive X‐ray diffraction and time‐resolved computed tomography simultaneously, establishing a powerful characterization methodology, which can also be applied more in general to carbon‐based energy‐related materials. A more in‐depth insight into the AlCl4−/graphite intercalation mechanism is obtained, evidencing a mixed‐staged region in the initial phase and a two‐staged region in the second phase. Moreover, strain analysis suggests a correlation between the irreversibility of the PG electrode and the increase of the inhomogenous strain. Finally, the imaging analysis reveals the influence of graphite morphology in the electrode volume expansion upon cycling.
- Green fabrication of hybrid materials as highly sensitive X-ray detectorsNew bismuth-based organic-inorganic hybrid materials show exceptional sensitivity and long-term stability as X-ray detectors, significantly more sensitive than commercial X-ray detectors. In addition, these materials can be produced without solvents by ball milling, a mechanochemical synthesis process that is environmentally friendly and scalable. More sensitive detectors would allow for a reduction in the radiation exposure during X-ray examinations.
- Electrical energy storage: BAM, HZB, and HU Berlin plan joint Berlin Battery LabThe Federal Institute for Materials Research and Testing (BAM), the Helmholtz-Zentrum Berlin (HZB), and Humboldt University of Berlin (HU Berlin) have signed a memorandum of understanding (MoU) to establish the Berlin Battery Lab. The lab will pool the expertise of the three institutions to advance the development of sustainable battery technologies. The joint research infrastructure will also be open to industry for pioneering projects in this field.
- BESSY II: Insight into ultrafast spin processes with femtoslicingAn international team has succeeded at BESSY II for the first time to elucidate how ultrafast spin-polarised current pulses can be characterised by measuring the ultrafast demagnetisation in a magnetic layer system within the first hundreds of femtoseconds. The findings are useful for the development of spintronic devices that enable faster and more energy-efficient information processing and storage. The collaboration involved teams from the University of Strasbourg, HZB, Uppsala University and several other universities.