Abstract
Complex metal hydride/oxide nanocomposites are a promising class of solid-state electrolytes. They exhibit high ionic conductivities due to an interaction of the metal hydride with the surface of the oxide. The exact nature of this interaction and composition of the hydride/oxide interface is not yet known. Using 1H, 7Li, 11B, and 29Si NMR spectroscopy and lithium borohydride confined in nanoporous silica as a model system, we now elucidate the chemistry and dynamics occurring at the interface between the scaffold and the complex metal hydride. We observed that the structure of the oxide scaffold has a significant effect on the ionic conductivity. A previously unknown silicon site was observed in the nanocomposites and correlated to the LiBH4 at the interface with silica. We provide a model for the origin of this silicon site which reveals that siloxane bonds are broken and highly dynamic silicon-hydride-borohydride and silicon-oxide-lithium bonds are formed at the interface between LiBH4 and silica. Additionally, we discovered a strong correlation between the thickness of the silica pore walls and the fraction of the LiBH4 that displays fast dynamics. Our findings provide insights on the role of the local scaffold structure and the chemistry of the interaction at the interface between complex metal hydrides and oxide hosts. These findings are relevant for other complex hydride/metal oxide systems where interface effects leads to a high ionic conductivity.
| Original language | English |
|---|---|
| Pages (from-to) | 8057-8066 |
| Number of pages | 10 |
| Journal | ACS Applied Energy Materials |
| Volume | 5 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 25 Jul 2022 |
Bibliographical note
Funding Information:Prof. Petra de Jongh is acknowledged for discussions and facilitating this research by making her laboratory available for sample synthesis and characterization. The authors also thank Hans Janssen, Gerrit Janssen, Marjan Versluijs-Helder, Hans Meeldijk, Dennie Wezendonk, and Jan Willem de Rijk for their technical support and discussions. Tom van Deelen is thanked for capturing the TEM images. Didier Blanchard is thanked for his assistance in the design of the setup for conductivity measurements. Tijs Smolders and Abhijit Wickramasinghe are acknowledged for their internship work preceding this manuscript. This project was supported by the Dutch Research Council (NWO), ECHO grant 712.015.005. NWO is further acknowledged for their support of the solid-state NMR facility for advanced materials science, which is part of the uNMR-NL grid (NWO grant 184.035.002). P.N. acknowledges funding from NWO Materials for Sustainability (grant 739.017.009).
Publisher Copyright:
© 2022 The Authors. Published by American Chemical Society.
Funding
Prof. Petra de Jongh is acknowledged for discussions and facilitating this research by making her laboratory available for sample synthesis and characterization. The authors also thank Hans Janssen, Gerrit Janssen, Marjan Versluijs-Helder, Hans Meeldijk, Dennie Wezendonk, and Jan Willem de Rijk for their technical support and discussions. Tom van Deelen is thanked for capturing the TEM images. Didier Blanchard is thanked for his assistance in the design of the setup for conductivity measurements. Tijs Smolders and Abhijit Wickramasinghe are acknowledged for their internship work preceding this manuscript. This project was supported by the Dutch Research Council (NWO), ECHO grant 712.015.005. NWO is further acknowledged for their support of the solid-state NMR facility for advanced materials science, which is part of the uNMR-NL grid (NWO grant 184.035.002). P.N. acknowledges funding from NWO Materials for Sustainability (grant 739.017.009).
Keywords
- lithium borohydride
- nanoconfinement
- silica
- solid-state electrolyte
- solid-state NMR