Rechargeable positive electrodes

• US 5,686,201 A
• Filed: 07/26/1996
• Issued: 11/11/1997
• Est. Priority Date: 11/23/1994
• Status: Expired due to Term

• Current Assignee: PolyPlus Battery Company
• Original Assignee: PolyPlus Battery Company
• Inventors: Chu, May-Ying
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US08/686,609
• Time in Patent Office: 473 Days
• Field of Search: 429/52, 429/102, 429/104, 429/103, 429/105, 429/190, 429/192, 429/194, 429/212, 429/218, 429/233, 429/213
• US Class Current: 429/52
• CPC Class Codes: C07C 227/32 by stereospecific synthesis
• CPC Class Codes: H01M 10/05 Accumulators with non-aqueous electrolyte H01M10/39 takes precedence
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0565 Polymeric materials, e.g. gel-type or solid-type
• CPC Class Codes: H01M 10/0569 characterised by the solvents
• CPC Class Codes: H01M 10/36 Accumulators not provided for in groups H01M10/05-H01M10/34
• CPC Class Codes: H01M 10/39 working at high temperature
• CPC Class Codes: H01M 10/3909 Sodium-sulfur cells
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 2004/028 Positive electrodes
• CPC Class Codes: H01M 2300/0065 Solid electrolytes
• CPC Class Codes: H01M 2300/0085 Immobilising or gelification of electrolyte
• CPC Class Codes: H01M 4/02 Electrodes composed of, or comprising, active material
• CPC Class Codes: H01M 4/04 Processes of manufacture in general
• CPC Class Codes: H01M 4/0402 Methods of deposition of the material
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/0409 by a doctor blade method, slip-casting or roller coating
• CPC Class Codes: H01M 4/0411 by extrusion
• CPC Class Codes: H01M 4/0416 involving impregnation with a solution, dispersion, paste or dry powder H01M4/0438 takes precedence
• CPC Class Codes: H01M 4/043 involving compressing or compaction
• CPC Class Codes: H01M 4/0435 : Rolling or calendering
• CPC Class Codes: H01M 4/0438 : by electrochemical processing electroless electrochemical plating C23C18/54
• CPC Class Codes: H01M 4/045 : Electrochemical coating; Electrochemical impregnation
• CPC Class Codes: H01M 4/13 : Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• CPC Class Codes: H01M 4/38 : of elements or alloys
• CPC Class Codes: H01M 4/382 : Lithium H01M4/405 takes precedence
• CPC Class Codes: H01M 4/581 : Chalcogenides or intercalation compounds thereof
• CPC Class Codes: H01M 4/5815 : Sulfides
• CPC Class Codes: H01M 4/60 : of organic compounds
• CPC Class Codes: H01M 4/62 : Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• CPC Class Codes: H01M 4/621 : Binders
• CPC Class Codes: H01M 4/624 : Electric conductive fillers
• CPC Class Codes: H01M 4/625 : Carbon or graphite
• CPC Class Codes: H01M 4/626 : Metals
• CPC Class Codes: H01M 50/46 : Separators, membranes or diaphragms characterised by their combination with electrodes
• CPC Class Codes: H01M 6/164 : by the solvent
• CPC Class Codes: H01M 6/168 : by additives
• CPC Class Codes: H01M 6/18 : with solid electrolyte
• CPC Class Codes: H01M 6/181 : with polymeric electrolytes
• CPC Class Codes: H01M 6/188 : Processes of manufacture
• CPC Class Codes: H01M 6/40 : Printed batteries , e.g. thin film batteries
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries

Abstract

Disclosed are positive electrodes containing active-sulfur-based composite electrodes. The cells include active-sulfur, an electronic conductor, and an ionic conductor. These materials are provided in a manner allowing at least about 10% of the active-sulfur to be available for electrochemical reaction. Also disclosed are methods for fabricating active-sulfur-based composite electrodes. The method begins with a step of combining the electrode components in a slurry. Next, the slurry is homogenized such that the electrode components are well mixed and free of agglomerates. Thereafter, before the electrode components have settled or separated to any significant degree, the slurry is coated on a substrate to form a thin film. Finally, the coated film is dried to form the electrode in such a manner that the electrode components do not significantly redistribute.

Claims

1. A method of preventing damage from overcharge, the method comprising the following steps:

(a) providing a metal-sulfur cell having a first cell voltage which it attains when fully charged but not overcharged, the cell including a metal negative electrode and a sulfur positive electrode which positive electrode includes

i) active-sulfur;

ii) an electronic conductor mixed with the active-sulfur so that electrons can move between the active-sulfur and the electronic conductor; and

iii) an ionic conductor mixed with the active-sulfur so that ions can move between the ionic conductor and the active-sulfur; and

(b) charging said metal-sulfur cell to a level beyond the normal charge capacity while the cell maintains an overcharge cell voltage that is not substantially higher than the first cell voltage, wherein the sulfur positive electrode has between about 10% and about 100% of the active-sulfur is available for electrochemical reaction.

2. The method of claim 1, wherein the overcharge cell voltage is not more than about 4 volts greater than the first cell voltage.

3. The method of claim 1, wherein the overcharge cell voltage is not more than about 2 volts greater than the first cell voltage.

4. The method of claim 1, wherein the overcharge cell voltage is not more than about 1 volt greater than the first cell voltage.

5. The method of claim 1 wherein the sulfur positive electrode is operated between about -40 degrees Celsius and about 180 degrees Celsius.

6. The method of claim 1 wherein the sulfur positive electrode contains, between about 20% by weight to about 80% by weight, active-sulfur.

7. The method of claim 1 wherein the electronic conductor is selected from the group consisting of carbon black, compounds with conjugated carbon-carbon or carbon-nitrogen double bonds, electronically conductive polymers, polyaniline compounds, polythiophene compounds, polyacetylene compounds, polypyrrole compounds, and combinations thereof.

8. The method of claim 1 wherein the sulfur positive electrode contains, between about 5% by weight to about 40% by weight, electronic conductor.

9. The method of claim 1 wherein the sulfur positive electrode contains between about 15% by weight and 75% by weight, ionic conductor, and wherein the ionic conductor is a solid or a gel.

10. The method of claim 9 wherein the ionic conductor is selected from the group consisting essentially of polymeric electrolytes, ceramic electrolytes, glass electrolytes, beta alumina compounds, and combinations thereof.

11. The method of claim 9 wherein the ionic conductor comprises an electrolyte salt that form a complex with compounds selected from the group consisting of polyether compounds, polyimine compounds, polythioether compounds, polyphosphazene compounds, polyalkylene oxide compounds, polyethylene oxide compounds, and amorphous polyethylene oxide compounds, and combinations thereof.

12. The method of claim 1 wherein the metal electrode is selected from the group consisting of lithium metal, lithium alloys, sodium metal, and sodium alloys.

13. The method of claim 12 wherein the metal electrode is a lithium electrode or a lithium alloy electrode.