Solid electrolyte for sodium batteries

Patent metadata

Field	Value
Publication number	US-2021066748-A1
Application number	US-201916961757-A
Country	US
Kind code	A1
Filing date	Jan 14, 2019
Priority date	Jan 12, 2018
Publication date	Mar 4, 2021
Grant date	—

Abstract

A class of improved solid-state electrolytes and methods for forming such electrolytes are discussed herein. The improved electrolytes may be a sodium oxy-sulfide, such as with a nominal composition of Na3PS4 _xOx (0<x≤2). The electrolytes can be synthesized from using a simple one-step ball-milling method. The ball-milling may be performed at high rotation speeds. The resulting ball-milled materials may further be optionally pressed. The pressing may be performed at low or room temperatures and/or relatively low pressure, and the resulting electrolytes achieve high relative densities. The solid-state electrolyte forms a highly dense layer that approaches a continuous glass that is nearly flawless, is mainly amorphous, and/or maintains a stable low-resistance interface with Na metal and Na-alloy electrodes.

First claim

What is claimed is:

1 . A method for forming an electrolyte comprising:
ball-milling starting materials comprising at least one sodium sulfide material and at least one oxide material; and pressing resulting ball-milled materials to form a sodium oxy-sulfide glass that is a solid-state electrolyte.

2 . The method of claim 1 , wherein the starting materials are Na 2 S, P 2 S 5 , and P 2 O 5 mixed with a molar ratio of 75:(25−y):y where y≠0.

3 . The method of claim 2 , wherein 0<y≤20.

4 . The method of claim 2 , wherein the sodium oxy-sulfide glass is Na 3 PS 4−x O x with 0<x≤2.

5 . The method of claim 4 , wherein x=0.25.

6 . The method of claim 1 , wherein the ball milling step is performed at 100° C. or less.

7 . The method of claim 1 , wherein the pressing step is performed at a pressure between 100-450 MPa.

8 . The method of claim 1 , wherein the electrolyte is a nearly flawless glass.

9 . The method of claim 8 , wherein the electrolyte is mainly amorphous.

10 . The method of claim 1 , wherein a relative density of the solid-state electrolyte is 95% or greater.

11 . The method of claim 1 , wherein the solid-state electrolyte is capable of performing 250 hours or longer with a Na metal or Na-based alloy electrode at 0.2 mA/cm 2 .

12 . The method of claim 1 , wherein the ball milling step is performed at 500 rpm or greater.

13 . A battery comprising:
at least one sodium metal or sodium-based alloy electrode; a second electrode; and a solid-state electrolyte, wherein the electrolyte comprises a sodium oxy-sulfide glass.

14 . The battery of claim 13 , wherein the sodium oxy-sulfide glass is a nearly flawless glass.

15 . The battery of claim 14 , wherein the sodium oxy-sulfide glass is mainly amorphous.

16 . The battery of claim 13 , wherein the sodium oxy-sulfide glass is Na 3 PS 4−x O x with 0<x≤2.

17 . The battery of claim 16 , wherein x=0.25.

18 . The battery of claim 13 , wherein a relative density of the sodium oxy-sulfide glass is 95% or greater.

19 . The battery of claim 13 , wherein the electrolyte further comprises other sulfide materials, and the other sulfide materials are sandwiched between the sodium oxy-sulfide glass.

20 . The battery of claim 13 , wherein the electrolyte is capable of performing 250 hours or longer with the sodium metal or the sodium-based alloy electrode at 0.2 mA/cm 2 .

Assignees

• Univ Houston System

Inventors

• Yao Yan
• Chi Xiaowei

Classifications

• H01M10/3918 Primary

  characterised by the electrolyte · CPC title

• H01M10/054

  Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium · CPC title

• H01M10/0562 Primary

  Solid materials · CPC title

• H01M2300/0071

  Oxides · CPC title

• C03C3/16 Primary

  containing phosphorus · CPC title