Metal-Halogenelectrochemical cell

• US 4,064,324 A
• Filed: 04/07/1976
• Issued: 12/20/1977
• Est. Priority Date: 04/07/1976
• Status: Expired due to Term

• Current Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Original Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Inventors: Eustace, Daniel J.
• Primary Examiner(s): Lefevour, C. F.
• Application Number:
  US05/674,584
• Time in Patent Office: 622 Days
• Field of Search: 429/101, 429/105, 429/198-201, 429/222, 429/229-231
• US Class Current: 429/101
• CPC Class Codes: H01M 10/365 Zinc-halogen accumulators

Abstract

An improved metal-halogen electrochemical cell particularly a zinc bromide cell, contains a water soluble organo substituted amino acid salt in the electrolyte which forms a substantially water insoluble liquid complex with cathodic halogen thereby reducing self-discharge of the cell.

Claims

1. In an electrochemical cell having a metal anode wherein the metal is selected from zinc and cadmium;

a bromine cathode;

an aqueous electrolyte containing a metal bromide, the metal bromide having the same metal as the metal of the anode, the improvement comprising;

a bromine complexing agent in said aqueous metal bromide electrolyte, said complexing agent consisting solely of a quaternary ammonium salt of an N-organo substituted alpha amino acid having the following formulas;

##STR9## wherein X³¹ is a halide anion selected from the group consisting of chloride and bromide ions, R₁, R₂, and R₃ are alkyl and haloalkyl groups of from 1 to 8 carbon atoms, which quaternary ammonium salt is soluble in water and forms a cathodically active halogen complex which is a substantially water immiscible liquid at temperatures in the range of from about 10°

to about 60°

C.

2. The cell of claim 1 wherein the anode metal is zinc.

3. The cell of claim 1 wherein the anode metal is cadmium.

4. The cell of claim 1 wherein the halide, X--, is bromide.

5. The cell of claim 1 wherein the quaternary ammonium salt is a nitrogen substituted carboxyethyl derivative of pyridine.

6. The cell of claim 1 wherein the quaternary ammonium salt is a nitrogen substituted carboxyethyl derivative of piperidine.

7. The cell of claim 1 wherein the amino acid salt is a nitrogen substituted carboxyethyl derivative of morpholine.

8. The cell of claim 1 wherein the amino acid is a betaine.

9. An aqueous metal halogen secondary battery including a plurality of electrochemical cells, said electrochemical cells comprising a zinc anode;

an inert counter-electrode;

an aqueous electrolyte, said aqueous electrolyte consisting essentially of an aqueous zinc bromide solution and a cathodically active bromine complex, which complex is a liquid at temperatures below 60°

C and which complex is substantially water immiscible, said bromine complex being formed solely between bromine and a water soluble quaternary ammonium salt of an N-organo substituted alpha amino acid, said salt being selected from those having the following formulas;

##STR10## wherein X-- is an anion selected from the group consisting of chloride and bromide ions, R₁, R₂ and R₃ are alkyl and haloalkyl groups of from 1 to 8 carbon atoms.

10. An aqueous zinc-bromine cell comprising:

a zinc anode;

a cathodically active bromine complex;

an inert electrode; and

an aqueous zinc bromide electrolyte said cathodically active bromine complex being formed solely between bromine and a water soluble quaternary ammonium salt of an N-organo substituted amino acid selected from those having the general formulas;

##STR11## wherein X-- is a halide ion selected from the group consisting of chloride and bromide ions, R₁, R₂ and R₃ are alkyl or haloalkyl groups of from 1 to 8 carbon atoms, and wherein said bromine complex of said N-organo substituted amino acid salt is a substantially water immiscible complex which is a liquid at temperatures ranging from about 10°

to about 60°

C.