Glass-Ceramic Sodium-Deficient Chlorides with High Sodium-ion Conductivity

23 November 2022, Version 1

Abstract

Solid-state batteries are a promising energy storage technology that can potentially offer both improved safety and energy density. The solid electrolyte is the defining feature and plays a significant role in the electrochemical performance of a solid-state cell, especially at room temperature. Herein, we report a series of glass-ceramic, sodium-deficient chloride solid electrolytes, NaxY0.25Zr0.75Cl3.75+x (0.25  x  0.875), possessing significantly improved ionic conductivities when compared to their stoichiometric counterpart, Na2.25Y0.25Zr0.75Cl6 (x = 2.25). By tuning both the sodium molar content and the sample’s crystallinity, the composition Na0.625Y0.25Zr0.75Cl4.375 (x = 0.625) was found to exhibit the highest Na+ conductivity of 0.4 mS cm−1 at room temperature. Furthermore, the relationship between composition, structure, and conductivity for these compositions in the NaCl−YCl3−ZrCl4 system was evaluated using a combination of X-ray diffraction (XRD), solid-state nuclear magnetic resonance spectroscopy (ss-NMR), and electrochemical impedance spectroscopy (EIS) techniques. Materials characterization reveals that sodium-deficiency (i.e., lower molar % of NaCl) results in reduced crystallinity and preferred occupancy of prismatic Na local environments. These combined factors contribute to a lower activation energy for Na+ hopping, an increased ionic conductivity, and improved electrochemical performance at both higher cycling rates and at room temperature.

Keywords

Solid-state Batteries
Halides
Solid Electrolyte
Sodium
Superionic

Supplementary materials

Title
Description
Actions
Title
Supplementary Information
Description
Supporting information pertaining to the main text.
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.