Wetting Na metal on the solid electrolyte of a liquid Na battery determines the operating temperature and performance of the battery. At low temperatures below 200 °C, liquid Na wets poorly on a solid electrolyte near its melting temperature (Tm = 98 °C), limiting its suitability for use in lowerature batteries used for large-scale energy-storage systems. Herein, we propose the use of sparked reduced graphene oxide (rGO) that can improve the Na wetting in sodium-beta alumina batteries (NBBs), allowing operation at lower temperatures. Experimental and computational studies indicated rGO layers with nanogaps exhibited complete liquid Na wetting regardless of the surface energy between the liquid Na and the graphene oxide, which originated from the capillary force in the gap. Employing sparked rGO significantly enhanced the cell performance at 175 °C; the cell retained almost 100% Coulombic efficiency after the initial cycle, which is a substantial improvement over cells without sparked rGO. These results suggest that coating sparked rGO is a promising but simple strategy for the development of lowerature NBBs.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation (NRF) of Korea through grants funded by the Korean government (2018M3D1A1058793, ERC-2015R1A5A1037668, and 2016M3A7B4910798). This work was also supported by grants from the International Collaborative Energy Technology R&D Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) (20158510050010) and by the Institute for Basic Science (IBS-R026-D1).
© 2019 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanical Engineering