Researchers from Empa and the University of Geneva have developed a prototype of a novel solid sodium battery with the potential to store extra energy.
Phones, laptops, electric cars – batteries are everywhere. And to meet the expectations of today’s consumers, these batteries are increasingly lighter, more powerful and designed to last longer. Currently the core technology for these applications is lithium ion batteries. But the technology is expensive and contains a flammable liquid, which may represent a safety hazard, when the battery is abused.
To satisfy the growing demand from emerging markets (electric cars, for example, and renewable energy storage), researchers from Empa, the Swiss Federal Laboratories for Materials Science and Technology, and the University of Geneva (UNIGE) have devised a new battery prototype: known as «all-solid-state», this battery has the potential to store more energy while maintaining high safety and reliability levels. Furthermore, the battery is based on sodium, a cheap alternative to lithium. Read about the research in more detail in the journal Energy and Environmental Science.
For a battery to work, it must have the following three key components: an anode (the negative pole), a cathode (the positive pole) and an electrolyte. Most of the batteries used in our electronic equipment today are based on lithium ions.
When the battery charges, the lithium ions leave the cathode and move to the anode. To prevent lithium dendrites forming – a kind of microscopic stalagmite that can induce short circuits in the battery that may cause fire – the anode in commercial batteries consists of graphite rather than metallic lithium, even though this ultra-light metal would increase the amount of energy that can be stored.
The Empa and UNIGE researchers focused on the advantages of a «solid» battery to cope with the heightened demand from emerging markets and to make batteries with even better performance: faster charging together with increased storage capacity and improved safety. Their battery uses a solid instead of a liquid electrolyte that enables the use of a metal anode by blocking the formation of dendrites, making it possible to store more energy while guaranteeing safety.
A non-flammable solid sodium battery
«But we still had to find a suitable solid ionic conductor that, as well as being non-toxic, was chemically and thermally stable, and that would allow the sodium to move easily between the anode and the cathode,» explains Hans Hagemann, professor in the Physical Chemistry Department in UNIGE’s Faculty of Sciences. The researchers discovered that a boron-based substance, a closo-borane, enabled the sodium ions to circulate freely. Furthermore, since the closo-borane is an inorganic conductor, it removes the risk of the battery catching fire while recharging. It is a material, in other words, with numerous promising properties.
«The difficulty was establishing close contact between the battery’s three layers: the anode, consisting of solid metallic sodium; the cathode, a mixed sodium chromium oxide; and the electrolyte, the closo-borane,» states Léo Duchêne, a researcher at Empa’s Materials for Energy Conversion lab and a PhD student in the Department of Physical Chemistry at UNIGE’s Faculty of Science. The researchers dissolved part of the battery electrolyte in a solvent before adding the sodium chromium oxide powder. Once the solvent had evaporated, they stacked the cathode powder composite with the electrolyte and anode, compressing the various layers to form the battery.
The team then tested the battery. «The electro-chemical stability of the electrolyte we are using here can withstand three volts, whereas many solid electrolytes previously studied are damaged at the same voltage,» says Arndt Remhof, a researcher at Empa and leader of the project, which is supported by the Swiss National Science Foundation (SNSF) and the Swiss Competence Centre for Energy Research on Heat and Electricity Storage (SCCER-HaE).
The scientists also tested the battery over 250 charge and discharge cycles, after which 85% of the energy capacity was still functional. «But it needs 1,200 cycles before the battery can be put on the market», say the researchers. «In addition, we still have to test the battery at room temperature so we can confirm whether or not dendrites form, while increasing the voltage even more. Our experiments are still ongoing.»
Karin Weinmann | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
Saving energy by taking a close look inside transistors
10.01.2019 | Friedrich-Alexander-Universität Erlangen-Nürnberg
Tandem Solar Cells – Record Efficiency for Silicon-based Multi-junction Solar Cell
08.01.2019 | Fraunhofer-Institut für Solare Energiesysteme ISE
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.
Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
17.01.2019 | Physics and Astronomy
17.01.2019 | Materials Sciences
17.01.2019 | Information Technology