Title: Towards novel solid-state batteries, magnesium and calcium electrolytes

Speaker: Prof.R. Jensen

Time: 11:00 AM, May 11,2026 

Venue: 3rd Floor Conference Room, Building B5, University Town Campus

Abstract:

Solid state batteries created using abundant and cheap elements may pave the way towards a more sustainable future. In particular, new approaches for direct storage of large amounts of renewable electricity both for mobile and stationary applications needs to be developed. Hydridoborates are built by polar-covalent chemical bonds, which provide ‘zero’ electronic conductivity and are therefore an excellent platform for development of electrolytes for solid state batteries. Hydridoborates can also contain neutral organic molecules that contributes to make the structures more open as compared to close-packed oxides and halides. Hydridoborate anions can coordinate to cations via a corner, an edge or a face and thereby contribute to structural flexibility and fast cationic conductivity. A new ligand assisted cationic conductivity mechanism was discovered, where a neutral molecule is exchanged between interstitial and framework cations. These phenomena contribute to the record-high divalent cationic conductivities at moderate temperatures observed for derivatives of magnesium and calcium tetrahydridoborates, e.g. β−Mg(BH4)2·CH3NH2, σ(Mg2+) = 1.5·104 Scm1 at RT [3]. A solid-state rechargeable magnesium battery using a magnesium metal anode, Mg(BH4)2·1.5THF−MgO(75 wt%, 50 nm) electrolyte, and a TiS2 cathode was developed with a cell voltage of 1.2 V. The highest calcium conductivities among solids were observed recently for a nano-composite material, Ca(BH4)2·4NH2CH3−MgO (50 wt%, 50 nm) reaching σ(Ca2+) = 1.3·10−4 S cm−1 at 60 °C .

Speaker Biography:

Torben R. Jensen obtained a PhD degree in materials chemistry at University of Southern Denmark (1999) and then joined Risø Natl. Lab. as a post doc, where he changed research topic to biophysics. He became Assistant Prof., at Chemistry Department, Aarhus University and associated to The Interdisciplinary Nanoscience center (iNANO) in 2000. Since then, he has assembled a unique and productive independent research group within energy materials science. The research achievements led to a Doctor of Science degree (D.Sc.) in 2014 and promotion to Professor in 2016. The research group has focused on the chemistry and physics of hydrogen and synthesised multitudes of new metal hydrides by combining solvent-based methods, mechanochemistry, and solid-gas reactions, etc. They also infiltrated hydrides in nanoporous scaffolds and conducted systematic studies of properties as a function of pore size and surface area to investigate the nano effects. The group lately discovered extremely dense packing of hydrogen in nanoporous matter and that weak dihydrogen bonds in the solid state facilitate fast cationic conductivity and demonstrated the hydrides are functional battery materials. They successfully made lithium and magnesium solid state batteries based on hydrides. Prof. Jensen published >390 scientific papers which received >20,000 citations (H = 71, scopus).