Processes for preparing 1-alkyl-3-alkyl-pyridinium bromide and uses thereof as additives in electrochemical cells

Patent metadata

Field	Value
Publication number	US-9722281-B2
Application number	US-201414765730-A
Country	US
Kind code	B2
Filing date	Feb 6, 2014
Priority date	Feb 7, 2013
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

The invention relates to the use of at least one 1-alkyl-3-alkyl-pyridinium halide, in particular 1-alkyl-3-methyl-pyridinium bromide, as an additive in bromine-generating electrochemical cells, such as zinc/bromine cells. Processes for preparing 1-alkyl-3-methyl-pyridinium bromide and concentrated aqueous solutions comprising same for use as additives in the aforementioned cells, are also disclosed.

First claim

The invention claimed is:

1. An electrolyte solution suitable for use in bromine-generating electrochemical cells, comprising an aqueous solution of zinc bromide and a liquid complex composed of at least one 1-alkyl-3-methyl-pyridinium halide combined with one or more bromine molecules, wherein said alkyl at position 1 is a C3-C10 alkyl group which may be either straight-chain or branched, wherein said electrolyte solution is configured for circulation in a zinc/bromine cell.

2. The electrolyte solution according to claim 1 , wherein the C3-C10 alkyl group is selected from the group consisting of n-propyl, n-butyl, n-pentyl and n-hexyl.

3. The electrolyte solution according to claim 2 , comprising 1-n-butyl-3-methyl-pyridinium bromide.

4. The electrolyte solution according to claim 3 , further comprising at least one compound selected from the group consisting of 1-n-propyl-3-methyl-pyridinium bromide, 1-n-pentyl-3-methyl-pyridinium bromide and 1-n-hexyl-3-methyl-pyridinium bromide.

5. The electrolyte solution according to claim 1 , wherein the electrolyte solution further comprises one or more compounds of Formulas I, II or III:

wherein:
in Formula (I), R 3 is hydrogen or alkyl group and R 4 is independently an alkyl group;
in Formula (II), X is null, —CH 2 — or —O—, and R 1 and R 2 are independently alkyl groups, with at least one of R 1 and R 2 being an alkyl group comprising not less than three carbon atoms; and
in Formula (III), R 5 and R 6 are independently an alkyl group.

6. The electrolyte solution according to claim 5 , wherein the compound of Formula (I) is selected from the group consisting of N-alkyl pyridinium bromide and 1-alkyl-2-methyl pyridinium bromide; the compound of Formula (II) is selected from the group consisting of N-methyl-N-alkyl pyrrolidinium bromide, wherein said alkyl group attached to the pyrrolidinium ring comprises not less than four carbon atoms; and the compound of Formula (III) is 1-alkyl-3-methyl imidazolium bromide.

7. The electrolyte solution according to claim 6 , wherein the compound of Formula (I) is selected from the group consisting of N-ethyl pyridinium bromide and 1-ethyl-2-methyl pyridinium bromide; the compound of Formula (II) is selected from the group consisting of N-methyl-N-butyl pyrrolidinium bromide, N-methyl-N-hexyl pyrrolidinium bromide and N-methyl-N-isooctyl pyrrolidinium bromide; and the compound of Formula (III) is 1-n-butyl-3-methyl imidazolium bromide.

8. The electrolyte solution according to claim 1 , wherein the liquid complex does not solidify at a temperature above 0° C.

9. A method of operating a bromine-generating electrochemical cell which is a zinc/bromine cell, comprising adding to the electrolyte of said cell at least one 1-alkyl-3-methyl-pyridinium halide, wherein the alkyl at position 1 is a C3-C10 alkyl group, which may be either straight-chain or branched; and charging and/or discharging said cell.

10. The method according to claim 9 , which further comprises adding to the electrolyte a compound of Formulas (I), (II) or (III):

wherein:
in Formula (I), R 3 is hydrogen or alkyl group and R 4 is independently an alkyl group;
in Formula (II), X is null, —CH 2 — or —O—, and R 1 and R 2 are independently alkyl groups, with at least one of R 1 and R 2 being an alkyl group comprising not less than three carbon atoms; and
in Formula (III), R 5 and R 6 are independently an alkyl group.

11. The method according to claim 9 , comprising forming a liquid complex composed of at least one 1-alkyl-3-methyl-pyridinium bromide combined with one or more bromine molecules, wherein said alkyl at position 1 is C3-C10 alkyl group which may be either straight-chain or branched, wherein the liquid complex does not solidify at a temperature above 0° C.

12. A process for preparing an aqueous solution of one or more 1-alkyl-3-methyl-pyridinium bromide, wherein the alkyl at position 1 is C3-C10 alkyl group, which may be either straight-chain or branched, comprising reacting 3-picoline and one or more bromoalkanes in a reaction vessel at a temperature above the melting point of the reaction mixture, in the absence of a solvent, combining the reaction product with water, wherein said reaction product consists essentially of 1-alkyl-3-methyl-pyridinium bromide in a liquid form, and recovering an aqueous solution of said 1-alkyl-3-methyl-pyridinium bromide.

13. The process according to claim 12 , which does not involve the formation, isolation and purification of the 1-alkyl-3-methyl-pyridinium bromide in a solid form.

14. The process according to claim 13 , wherein the solvent-free reaction mixture is heated to a temperature of not less than 70° C., maintaining the progressively formed 1-alkyl-3-methyl-pyridinium bromide in a liquid form and providing a stirrable reaction mass, and combining the liquid 1-alkyl-3-methyl-pyridinium bromide directly with water to form a clear aqueous solution.

15. A concentrated aqueous solution comprising at least one 1-alkyl-3-methyl-pyridinium bromide, wherein the alkyl at position 1 is C3-C10 alkyl group, which may be either straight-chain or branched, wherein the concentration of the solution is from 60 wt % to 90 wt %.

16. The concentrated aqueous solution according to claim 15 , comprising at least one 1-alkyl-3-methyl-pyridinium bromide selected from the group consisting of 1-n-propyl-3-methyl-pyridinium bromide, 1-n-butyl-3-methyl-pyridinium bromide, 1-n-pentyl-3-methyl-pyridinium bromide and 1-n-hexyl-3-methyl-pyridinium bromide.

17. The concentrated aqueous solution according to claim 16 , further comprising 1-ethyl-3-methyl pyridinium bromide.

18. The concentrated aqueous solution according to claim 15 , wherein the 1-alkyl-3-methyl-pyridinium bromide was isolated in a non-solid form.

Assignees

• Bromine Compounds Ltd

Inventors

• Magnes Ben-Zion
• Ben David Iris
• Lancry Eli
• Bergstein-Freiberg Mira
• Zer-Zion Nirit

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• C07D213/20 Primary

  Quaternary compounds thereof · CPC title

• H01M2300/0002

  Aqueous electrolytes · CPC title

• Y02E60/128

  Cross-Sectional Technologies · mapped topic

• H01M8/188

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title