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

• US 9,997,767 B2
• Filed: 09/05/2014
• Issued: 06/12/2018
• 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:
  US14/478,843
• Publication Number:
  US 20150064561A1
• Time in Patent Office: 1,376 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. An electrode which has not been subject to a charge-discharge cycle, comprising an iron active material, a polyvinyl alcohol binder and sulfur, which electrode surface has an oxidized iron surface and areas of interparticle contact that are in an oxidized state different from the oxidized iron surface, which electrode is prepared by a process comprising:

i) fabricating an electrode comprising an iron active material, 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 electrode of claim 1, wherein the oxidation state of the oxidized iron surface is +2, +2/+3, +3 or +4.

3. The electrode of claim 1, wherein the electrode further comprises a conductive additive.

4. The electrode of claim 3, wherein the conductive additive comprises nickel, or copper or carbon black.

5. The electrode of claim 1, wherein the electrode comprises an iron active material comprising about:

50-90 wt % iron powder

5-30 wt % nickel powder

0.5-5.0 wt % binder, and

0.25-20 wt % sulfur.

6. The electrode of claim 1, wherein the electrode comprises a single layer of conductive substrate coated on at least one side with a coating comprising the iron active material.

7. The electrode of claim 6, wherein the substrate is comprised of nickel plated steel.

8. The electrode of claim 1, wherein the porosity of the electrode is in the range of about 15-50%.