Tuesday 27 January 2026 2:00pm to 3:00pm
Wolfson Lecture Theatre, Yusuf Hamied Department of Chemistry
About
INFORMAL MATERIALS RIG SEMINAR
Professor Robert Armstrong
CNRS Principal Research Fellow, School of Chemistry - University of St Andrews
https://research-portal.st-andrews.ac.uk/en/persons/robert-armstrong/
ABSTRACT:
The development of high-performance electrode materials is essential to the successful commercialisation of sodium-ion batteries. Among positive electrodes sodium layered oxides, NaxTMO2, demonstrate high energy densities and versatile chemistry and crystal structures (typically P2 or O3). P2-type oxides generally show excellent high-rate and cycling performance, but low Na content (x < 0.7) limits the full cell energy density. O3-type materials show high initial Na content (0.8 < x < 1) but suffer from poor rate capability and cycling stability. Recent work on the less-studied P3 phase has shown that Na contents approaching those of O3 are possible whilst delivering good rate performance. In this work, by forming composites of the different polymorphs, we combine high initial Na contents with P2-type cycling behaviour by tuning the synthesis conditions. The resulting series of materials displays high energy densities and cycling stabilities. Thorough structural and electrochemical characterisation reveals the relationship between chemical composition, crystal structure and the resulting electrochemical performance, providing critical insights for the rational design of high-performance positive electrode materials.
In the case of negative electrodes, organic compounds or solids with organic backbones have shown immense promise as sustainable electrode materials, as they are composed of naturally abundant elements, can be functionalized, and their electrochemistry is versatile. However, they are limited by poor electronic conductivity. Here we demonstrate, by forming a composite with commercial hard carbon, that it is possible to overcome this limitation while retaining the superior rate performance compared with the carbon alone.