Mesoporous network electrode for electrochemical cell

• US 20040131934A1
• Filed: 09/19/2003
• Published: 07/08/2004
• Est. Priority Date: 03/20/2001
• Status: Abandoned Application

• Current Assignee: Xoliox SA
• Original Assignee: Xoliox SA
• Inventors: Pappas, Nicholas, Graetzel, Michael, Sugnaux, Francois
• Application Number:
  US10/472,732
• Publication Number:
  US 20040131934A1
• Time in Patent Office: Days
• US Class Current: 429/209
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02F 1/1503 caused by oxidation-reduction reactions in organic liquid solutions, e.g. viologen solutions
• CPC Class Codes: G02F 1/155 Electrodes
• CPC Class Codes: G02F 2001/1502 complementary cell
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials
• CPC Class Codes: H01G 11/24 characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
• CPC Class Codes: H01G 11/38 Carbon pastes or blends; Binders or additives therein
• CPC Class Codes: H01G 11/48 Conductive polymers
• CPC Class Codes: H01G 11/56 Solid electrolytes, e.g. gels; Additives therein
• CPC Class Codes: H01G 9/2027 comprising an oxide semiconductor electrode
• CPC Class Codes: H01G 9/2031 comprising titanium oxide, e.g. TiO2 H01G9/2036 takes precedence
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• 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 4/13 Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/362 Composites
• CPC Class Codes: H01M 4/485 of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy H01M4/505, H01M4/525 take precedence
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/525 : of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H01M 50/434 : Ceramics
• CPC Class Codes: H01M 50/46 : Separators, membranes or diaphragms characterised by their combination with electrodes
• CPC Class Codes: H01M 6/40 : Printed batteries , e.g. thin film batteries
• CPC Class Codes: Y02E 10/542 : Dye sensitized solar cells
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02E 60/13 : Energy storage using capacitors

Abstract

A high kinetics rate electrochemical cell in which at least one of the electrodes is composed of a mesostructural electroactive material comprising nanoparticles forming a three-dimensional framework structure of mesoporous texture having a bicontinuous junction of large specific surface area with the electrolyte. A low temperature method of preparation of the electrodes employs a high-speed deposition of the electrically active material in the form of a thin film. The application of said electrodes in high power lithium ion insertion batteries, photovoltaic cells, supercapacitors and fast electrochromic devices is disclosed.

Claims

1. An electrode comprising:

(a) an electrode active material that exhibits a mesoporous porosity, as measured by nitrogen porosimetry using the desorption isotherm, wherein the electrode active material comprises discrete solid contacting particles comprising nanoparticles and optionally microparticles;

(b) a curable organic binder; and

(c) an electrical conduction means operatively associated with the electrode active material.

2. An electrode according to claim 1 wherein said electrode active material is selected from the group comprising an oxide, chalcogenide, hydroxide, oxyhydroxide, oxo-acid, oxohydride or thiocyanic acid of a non-transition or transition metal, or its lithiated or partially lithiated form selected from the group consisting of Group IB, IIA, IIB, IIIA, IVA, IVB, VA, VB, VIIB, VIIB and VIII elements of the Periodic Table of Elements, and blends thereof.

3. An electrode according to claim 1 or 2 wherein said electrode active material comprises a bimodal particle size distribution, the particles comprising at least 10% by weight of nanoparticles having an average size of less than 50 nm and microparticles having a size above 50 nm, having a specific surface area of from 0.1 m²/g to 500 m²/g.

4. An electrode according to any of claims 1 to 3 wherein said electrode active material is substantially free of microparticles and comprises nanoparticles which exhibit an electrochemical activity and are in the form of an hexagonal or cubic array of substantially uniformly sized particles.

5. An electrode according to any of claims 1 to 4 wherein said curable organic binder is used in an amount of from 0.5% to 10%, preferably from 1% to 5%, by weight of said particles and comprises a polymeric material with a glass transition temperature of at least 50°

C., preferably selected from polyvinylidene fluoride, polytetrafluoroethylene, fluororubber (which is a terpolymer of tetrafluoroethylene, vinylidene fluoride and hexafluoropropylene), polyvinyl polymers such as polyvinylpyrrolidone, polyamides, polyurethanes;

ethylene acrylic acid (EAA) copolymers, ethylene methacrylic acid (EMAA) copolymers, polyethylene (PE), polypropylene (PP), ethylene-propylene-diene terpolymers (EPDM), polyalkylene oxides, polybutylene, ionically cross-linked ethylene methacrylic acid copolymer, ethylene n-butyl acrylate (EnBA) polymers, ethylene vinyl acetate (EVA) polymers, ethylene ethyl acrylate (EEA) copolymer, ethylene methyl acrylate (EMA) copolymer, bisallylnadiimide or allylnadiimide, polysulfones, polyethersulfones, polyimides, polyamide-imides, epoxy resins, polyarylene ether ketones such as chloromethylated polyarylene ether ketones, acryloylated polyarylene ether ketones, polyacrylonitrile, a nitrile rubber, an ethylene-propylene rubber, a styrene-butadiene rubber, polyetherimides, polystyrene, cholromethylated polyethersulfones, acryloylated polyethersulfones, polymethyl methacrylate, a polysulfide rubber, cyanoethyl cellulose, methyl cellulose, and oligomers and blends thereof;

or precursors thereof selected from thiophene, phenylene, pyrrole, acetylene, isothionaphtene, aniline, ethylenedioxythiophene, phenylenevinylene and acrylonitrile, and non-doped, doped and substituted derivatives thereof and co-polymers thereof.

6. An electrode according to any of claims 1 to 5 wherein said curable organic binder is further blended or substituted with an electronic conductive material selected from the group consisting of a non-doped or doped intrinsically conductive polymer, polythiophene, polyphenylene, polypyrrole, polyacetylene, polyisothionaphthene, polyaniline, polyethylenedioxythiophene (PEDOT), poly(phenylenevinylene), electrically conductive ladder polymer formed from acrylonitrile and the like, substituted derivatives thereof and co-polymers thereof, a conductive particle, carbon black, fine particles of carbon, of graphitised carbon, of graphite, acetylene black, carbon whiskers, carbon nanotubes, fullerenes, highly conductive colloidal metals and doped metal oxides, alloys of said metals, metallic nano-fibers, and mixtures thereof.

7. An electrode according to any of claims 1 to 6 wherein the electrically conductive means is disposed on a support formed from a plastics material.

8. An electrode according to any of claims 1 to 7 wherein said electrode active material is doped by substitution of a solid solution, wherein from 0.2% to 49% of the atoms of the non-transition or transition metal are substituted by another transition or non-transition metal selected from the group consisting of Group IB, IIB, IIIA, IVA, IVB, VA, VB, VIIB, VIIB and VIII elements of the Periodic Table of Elements, and blends thereof.

9. An electrode according to any claims 1 to 8 wherein the electrode active material is modified by the adsorption thereto of a sensitizing dye, a redox chromophore, or a charge transfer sensitizer.

10. An electrochemical cell comprising one or more electrodes as defined in any of claims 1 to 9.

11. An electrochemical cell according to claim 10 wherein the electrode active material of the or each electrode comprises nanoparticles that are assembled as discrete contacting particles to form a mesoporous reticulated three dimensional bicontinuous structure comprising an electrically interconnected solid phase material in contact with interconnected interparticular space for containing electrolyte.

12. An electrochemical cell according to claim 10 wherein the electrode active material of the or each electrode comprises nanoparticles that are assembled as discrete contacting particles to form a mesoporous reticulated three dimensional bicontinuous structure comprising an electrically interconnected solid phase material in contact with interconnected interparticular space comprising electrolyte.

13. An electrochemical cell according to any of claims 10 to 12 comprising a positive electrode and a negative electrode, wherein the electrode active layer of the positive and/or negative electrode further comprises an inactive layer, serving as a porous separator to prevent direct contact and short circuiting of the positive and negative electrodes, said separator preferably being selected from an insulating ceramic material, more preferably Al₂O₃, SiO₂, silanized silica, ZrO₂, Ta₂O₅ or LiLa_0.35Ti_0.55O₃.

14. An electrochemical cell according to claim 13 wherein the porous separator additionally comprises a curable organic binder, preferably an organic binder as defined in claim 5 or 6.

15. An electrochemical cell according to any of claims 10 to 14 in the form of a high power ion insertion battery;

or in the form of a high power supercapacitor;

or in the form of a hybrid cell comprising a supercapacitor electrode and an ion insertion battery electrode.

16. Use of an electrochemical cell according to any of claims 10 to 15 in a photovoltaic cell, or in an electrochromic device, or in an ion insertion battery capable of delivering current in a biphasic manner.

17. A process for preparing an electrode according to any of claims 1 to 9 comprising providing a colloidal dispersion of the electrode active material, mixing the dispersion with the curable organic binder and depositing the resulting mixture at a temperature of from 5°

C. to 60°

C. on a support to produce an electrode active layer, said layer being subsequently dried at a temperature below the boiling temperature of the liquid used to prepare the dispersion.

18. A process according to claim 17 further comprising disposing an inactive insulating separator material on the electrode active layer, the separator material optionally comprising a curable organic binder.

19. A process according to claim 17 or 18 further comprising curing the binder in the electrode active layer and in the separator material if present, preferably by means of electromagnetic radiation and/or UV radiation and ozone and/or heating, preferably at a temperature in the range of from 70°

C. to 240°

C., more preferably from 90°

C. to 170°

C.

20. A process according to any of claims 17 to 19 wherein pressure is applied after the casting of the electrode active material and optionally the separator material.

21. A process according to any of claims 17 to 20 additionally comprising coating the mesoporous electrode with an electrically conductive metal or metal oxide layer by a coating method preferably selected from evaporation, sputtering, metallic powder blasting and metallic powder printing.