Anion binding agent lithium salts for battery electrolytes

Patent metadata

Field	Value
Publication number	US-11845765-B1
Application number	US-202017080935-A
Country	US
Kind code	B1
Filing date	Oct 27, 2020
Priority date	Jan 31, 2018
Publication date	Dec 19, 2023
Grant date	Dec 19, 2023

Abstract

A method for synthesizing a purified lithium (Li) + anion binding agent (ABA-F) − salt and the corresponding Li + (ABA-F) − are disclosed. The method includes dissolving a boron-based acid in a polar solvent to form a solution. The solution is refluxed to form an anion binding agent. A stoichiometric amount of a small fluorinated salt, such as LiF, is added to the anion binding agent to form a mixture. The mixture is subsequently crystallized to obtain a substantially pure Li + (ABA-F) − salt. Example purified Li + (ABA-F) − salts include Ox-Li + (ABA-F), m-Li + (ABA-F), and BF 3 —Li + (ABA-F) − . These purified Li + (ABA-F) − salts provide the benefits of increased battery thermal safety without loss of electrochemical performance.

First claim

The invention claimed is:

1. A process for synthesizing a purified lithium salt comprising the steps of:
dissolving at least one boron-based acid and at least one of an oxalic and a malonic acid in a first solvent to form a first solution;
refluxing the first solution and removing water therefrom using distillation to form a first mixture;
vacuum filtrating the first mixture to form a first filtrate;
washing the first filtrate with a non-polar solvent to form an anion binding agent;
dissolving the anion binding agent in a polar solvent to form a second solution;
adding a small fluorinated salt to the second solution to form a second mixture;
filtering the second mixture to form a second filtrate; and
evaporating the second filtrate to obtain the purified lithium salt.

2. The process of claim 1 , wherein the boron-based acid includes at least one of pentafluorobenzene boronic acid, trifluoromethyl boronic acid, and pentachlorobenzene boronic acid.

3. The process of claim 1 , wherein the first solvent includes one or more of acetone, toluene, dimethyl sulfoxide, methanol, and dimethylcarbonate.

4. The process of claim 1 , wherein the non-polar solvent is diethyl ether.

5. The process of claim 1 , wherein the polar solvent is acetone.

6. The process of claim 1 , wherein the small fluorinated salt is lithium fluoride (LiF) or lithium tetrafluoroborate (LiBF 4 ).

7. The process of claim 1 , wherein a peak normalized heating rate for the purified lithium salt is less than 25° C./min.

8. A process for synthesizing a purified lithium salt comprising the steps of:
dissolving at least one boron-based acid in a first solvent to form a first solution;
adding hydrofluoric acid to the first solution to form a second solution;
adding potassium hydroxide to the second solution to form a first precipitate;
collecting the first precipitate by vacuum filtration to form a first filtrate;
washing the first filtrate with methanol to form a third solution;
drying the third solution to form an anion binding agent;
adding LiBF 4 to the anion binding agent to form a second precipitate;
filtering the second precipitate to form a second filtrate; and
evaporating the second filtrate to obtain the purified lithium salt.

9. The process of claim 8 , wherein the boron-based acid includes at least one of pentafluorobenzene boronic acid, trifluoromethyl boronic acid, and pentachlorobenzene boronic acid.

10. The process of claim 8 , wherein the first solvent includes one or more of acetone, toluene, dimethyl sulfoxide, methanol, and dimethylcarbonate.

11. The process of claim 8 , wherein a peak normalized heating rate for the purified lithium salt is less than 25° C./min.

Assignees

• Nat Tech & Eng Solutions Sandia Llc

Inventors

• Orendorff Christopher
• Nagasubramanian Ganesan
• Fenton Kyle R
• Ingersoll David
• Pratt Harry
• Staiger Chad
• Anderson Travis Mark

Classifications

• C07F5/02 Primary

  Boron compounds · CPC title

• B01D9/005

  Selection of auxiliary, e.g. for control of crystallisation nuclei, of crystal growth, of adherence to walls; Arrangements for introduction thereof · CPC title

• B01D9/0022

  by reducing pressure · CPC title

• B01D9/0045

  Washing of crystals, e.g. in wash columns · CPC title

• B01D9/0059

  General arrangements of crystallisation plant, e.g. flow sheets · CPC title