Batteries without critical raw materials
With operando techniques, it is possible to observe how solvated ions embed themselves in batterie electrodes. This might help to develop alternative batteries. © G. A. Ferrero
The market for rechargeable batteries is growing rapidly, but the necessary raw materials are limited. Sodium-ion batteries, for example, could offer an alternative. A joint research group from HZB and Humboldt-Universität zu Berlin has investigated new combinations of electrolyte solutions and electrode materials for this purpose.
"In contrast to lithium-ion batteries, which are based on the storage of lithium ions in the positive and negative electrodes of the battery, we are working on the one hand with sodium ions, as they also occur in cheap table salt. On the other hand, we store the sodium ions together with their solvate shell, i.e. solvent molecules from the electrolyte solution that separate the two electrodes. This makes it possible to realise completely new storage reactions," explains Prof. Philipp Adelhelm, who heads the research group "operando battery analysis", which was jointly founded by Humboldt University and Helmholtz-Zentrum Berlin in 2020.
The storage of ions when accompanied by their solvation shell in a crystal lattice is referred to as co-intercalation. Up to this point, this concept was limited to the negative electrode of the sodium-ion battery. Now the researchers around Adelhelm have succeeded in extending the concept to the positive electrode of the battery. Dr. Guillermo A. Ferrero, first author of the publication, explains: "With titanium disulphide and graphite, we have for the first time combined two materials that absorb and release the same solvent during charging and discharging of the battery”. The scientists could observe changes in the material during charging and discharging via operando measurements performed in the X-Ray Core Lab at HZB on the LIMAX 160. This helped them to assign the co-intercalation mechanism inside the battery. They could then use this new knowledge to realise a battery with two electrodes that both rely on reversible co-intercalation of solvent molecules.
“We are still in the early stages of understanding the implications of the co-intercalation batteries. But there are a few possible advantages we can envision”, Dr. Katherine A. Mazzio, HZB, explains: The process of co-intercalation could improve upon efficiency by enabling better low temperature performance. It could also be utilised to improve upon alternative cell concepts such as using multi-valent ions instead of Li+ or Na+ storage that are particularly sensitive to the solvation shell.”
Note: This project received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. [864698], SEED).
- Bright prospects for tin perovskite solar cellsPerovskite solar cells are widely regarded as the next generation photovoltaic technology. However, they are not yet stable enough in the long term for widespread commercial use. One reason for this is migrating ions, which cause degradation of the semiconducting material over time. A team from HZB and the University of Potsdam has now investigated the ion density in four different, widely used perovskite compounds and discovered significant differences. Tin perovskite semiconductors produced with an alternative solvent had a particular low ion density — only one tenth that of lead perovskite semiconductors. This suggests that tin-based perovskites could be used to make solar cells that are not only really environmentally friendly but also very stable.
- Synchrotron radiation sources: toolboxes for quantum technologiesSynchrotron radiation sources generate highly brilliant light pulses, ranging from infrared to hard X-rays, which can be used to gain deep insights into complex materials. An international team has now published an overview on synchrotron methods for the further development of quantum materials and technologies in the journal Advanced Functional Materials: Using concrete examples, they show how these unique tools can help to unlock the potential of quantum technologies such as quantum computing, overcome production barriers and pave the way for future breakthroughs.
- Joint Kyiv Energy and Climate Lab goes liveHelmholtz-Zentrum Berlin and the National University of Kyiv-Mohyla Academy established on 27 November a Joint Energy and Climate Lab.