Accelerated formation and increased performance in chemically pre-formed (CPF) iron negative electrodes

• US 10,418,621 B2
• Filed: 05/15/2018
• Issued: 09/17/2019
• Est. Priority Date: 09/05/2013
• Status: Active Grant

• Current Assignee: Encell Technology, Inc
• Original Assignee: Encell Technology, Inc
• Inventors: Ogg, Randy Gene, Roders, Michael, Meese, Michael
• Primary Examiner(s): Godenschwager, Peter F
• Assistant Examiner(s): Oyer, Andrew J.
• Application Number:
  US15/980,088
• Publication Number:
  US 20180261826A1
• Time in Patent Office: 490 Days
• CPC Class Codes: H01M 4/049 Manufacturing of an active layer by chemical means
• CPC Class Codes: H01M 4/248 Iron electrodes
• CPC Class Codes: H01M 4/26 Processes of manufacture
• CPC Class Codes: H01M 4/38 of elements or alloys
• CPC Class Codes: H01M 4/5815 Sulfides
• CPC Class Codes: H01M 4/62 Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• CPC Class Codes: H01M 4/624 Electric conductive fillers
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Provided is a process for preparing an electrode comprising an iron active material. The process comprises first fabricating an electrode comprising an iron active material, and then treating the surface of the electrode with an oxidant to thereby create an oxidized surface. The resulting iron electrode is preconditioned prior to any charge-discharge cycle to have the assessable surface of the iron active material in the same oxidation state as in discharged iron negative electrodes active material.

Claims

1. A process for preparing an electrode comprising an iron active material, which comprises:

i) fabricating an electrode comprising an iron active material, a polyvinyl alcohol binder and sulfur, and

ii) treating the surface of the electrode with an oxidant to thereby create an oxidized surface prior to the electrode being subjected to a charge-discharge cycle.

2. The process of claim 1, wherein the oxidation state of the iron active material in the oxidized surface is +2, +2/+3, +3 or +4.

3. The process of claim 1, wherein a binder is added to the electrode during the fabricating of the electrode.

4. The process of claim 1, wherein the sulfur is added to the electrode during the fabricating of the electrode.

5. The process of claim 1, wherein a conductive additive is added to the electrode during the fabricating of the electrode.

6. The process of claim 5, wherein the conductive additive comprises nickel, or copper or carbon black.

7. The process of claim 1, wherein the fabricating of the electrode comprises mixing an iron active material, nickel powder, a binder and sulfur.

8. The process of claim 7, wherein the fabricating of the electrode results in an electrode comprising:

50-90 wt % iron powder

5-30 wt % nickel powder

0.5-5.0 w % binder, and

0.25-20 w % sulfur.

9. The process of claim 1, wherein the fabricating of the electrode comprises coating a single layer of the iron active material on at least one side of a conductive substrate.

10. The process of claim 9, wherein the substrate is comprised of nickel plated steel.

11. The process of claim 1, wherein the porosity of the electrode fabricated in step i) is in the range of about 15-50%.