Affiliation:
1. Henan Key Laboratory of Boron Chemistry and Advanced Materials School of Chemistry and Chemical Engineering Henan Normal University Xinxiang Henan 453007 China
2. College of Chemistry Zhengzhou University Zhengzhou Henan 450001 China
3. Department of Chemistry and Biochemistry The Ohio State University Columbus OH 43210 USA
Abstract
AbstractSolid‐state sodium metal batteries have been extensively investigated because of their potential to improve safety, cost‐effectiveness, and energy density. The development of such batteries urgently required a solid‐state electrolyte with fast Na‐ion conduction and favorable interfacial compatibility. Herein, the progress on developing the NaB3H8 solid‐state electrolytes is reported, which show a liquid‐like ionic conductivity of 0.05 S cm−1 at 56 °C with an activation energy of 0.35 eV after an order‐disorder phase transformation, matching or surpassing the best single‐anion hydridoborate conductors investigated up to now. The steady polarization voltage and significantly decreased resistance are achieved in the symmetric Na/NaB3H8/Na cell, indicating the great electrochemical stability and favorable interfacial contact with the Na metal of NaB3H8. Furthermore, a Na/NaB3H8/TiS2 battery, the first high‐rate (up to 1 C) solid‐state sodium metal battery using the single‐anion hydridoborate electrolyte, is demonstrated, which exhibits superior rate capability (168.2 mAh g−1 at 0.1 C and 141.2 mAh g−1 at 1 C) and long‐term cycling stability (70.9% capacity retention at 1 C after 300 cycles) at 30 °C. This work may present a new possibility to solve the interfacial limitations and find a new group of solid‐state electrolytes for high‐performance sodium metal batteries.
Funder
National Natural Science Foundation of China