Halide solid electrolytes (SEs) are emerging as an alternative to sulfide and/or oxide SEs for applications in all-solid-state batteries owing to the advantage fulfilling high (electro)chemical stability and mechanical sinterability at the same time. Thus far, the developments in halide SEs have focused on Li+ superionic conductors. Herein, the development of a new Na+-conducting halide SE, mechanochemically prepared Na2ZrCl6 (1.8 × 10−5 S cm−1 at 30°C) with excellent oxidative electrochemical stability, is described. A trigonal crystal structure with the P3¯m1 symmetry is successfully identified by the Rietveld refinement of X-ray diffraction. Additionally, the bond valence sum energy level calculations disclose one-dimensional preferable Na+-diffusion channels in Na2ZrCl6. It is to be noted that despite the rather low Na+ conductivity of Na2ZrCl6, NaCrO2 electrodes that uses Na2ZrCl6 in NaCrO2/Na-Sn all-solid-state Na-ion batteries demonstrate an exceptionally high initial Coulombic efficiency of 93.1% and a high reversible capacity of 111 mA h g−1 at 0.1C and 30 °C (98.4% and 123 mA h g−1 at 60 °C), highlighting the excellent electrochemical stability of Na2ZrCl6.
Bibliographical noteFunding Information:
This research was supported by the Technology Development Program to Solve Climate Changes and by Basic Science Research Program of the National Research Foundation (NRF) funded by the Ministry of Science & ICT (grant no. NRF-2017M1A2A2044501 and 2018R1A2B6004996), and by the Materials and Components Technology Development Program of MOTIE/KEIT (grant no. 20007045 and 20012216).
© 2021 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
- Energy Engineering and Power Technology