EP1179220A2 - Cathodes a base de soufre a composant unique destinees aux piles a lithium et ion-lithium - Google Patents

Cathodes a base de soufre a composant unique destinees aux piles a lithium et ion-lithium

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Publication number
EP1179220A2
EP1179220A2 EP00907101A EP00907101A EP1179220A2 EP 1179220 A2 EP1179220 A2 EP 1179220A2 EP 00907101 A EP00907101 A EP 00907101A EP 00907101 A EP00907101 A EP 00907101A EP 1179220 A2 EP1179220 A2 EP 1179220A2
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EP
European Patent Office
Prior art keywords
conducting polymer
sulfur
cathode material
species
cathode
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EP00907101A
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German (de)
English (en)
Inventor
John Pope
Dan Buttry
Shannon White
Robert Corcoran
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Blue Sky Batteries Inc
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Blue Sky Batteries Inc
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Publication of EP1179220A2 publication Critical patent/EP1179220A2/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/137—Electrodes based on electro-active polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G61/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G61/12—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G61/00—Macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain of the macromolecule
    • C08G61/12—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule
    • C08G61/122—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule derived from five- or six-membered heterocyclic compounds, other than imides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0411—Methods of deposition of the material by extrusion
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0438—Processes of manufacture in general by electrochemical processing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0438—Processes of manufacture in general by electrochemical processing
    • H01M4/0464—Electro organic synthesis
    • H01M4/0466—Electrochemical polymerisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H01M4/602—Polymers
    • H01M4/606—Polymers containing aromatic main chain polymers
    • H01M4/608—Polymers containing aromatic main chain polymers containing heterocyclic rings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates generally to cathodes for rechargeable batteries. More particularly, the present invention relates to cathode materials based on conducting polymers and sulfur or selenide species and the method of selecting conducting polymers and sulfur or selenide species. The selection method accounts for characteristics of the conducting polymer and the sulfur or selenide species and the specific capacity, capacity fade, charge and discharge rate, physical and chemical stability, safety and other characteristics associated with battery cycles. More particularly, the present invention relates to a single component sulfur-based conducting polymer for use in lithium batteries and the synthesis of such material.
  • lithium and lithium-ion batteries represent the most promising technologies, especially in terms of their attractive energy densities when compared to nickel cadmium and nickel-metal hydride cells.
  • This promise can be attributed in large part to the extremely high specific capacity available in theory from lithium (3862 A h/kg) and the reasonable charge capacity available from lithium-intercalated carbon (e.g. for LiC 6 , 372 A h/kg) anodes.
  • Batteries currently marketed utilize LiCoO 2 cathodes, a material that has a theoretical specific capacity of 274 A h/kg and a practical specific capacity of 100 to 150 A h/kg. In realistic terms, then, cells using LiCoO 2 can utilize only one-thirtieth of the potential energy per gram stored in lithium metal (or only one-third of the potential energy per gram stored in LiC 6 ). While batteries based on such cathodes are suitable to meet short-term commercial needs, significant progress in this area must be based around developing cathodes with specific capacities similar to those of the best available anodes.
  • sulfur and sulfur- containing compounds offer the best opportunities in terms of high theoretical specific capacities.
  • Sulfur cathodes operate by storing energy as disulfide bridges, a very stable oxidized material, then releasing it by reducing to thiolate moieties. This process is illustrated in Figure 1 for one material. While sulfur cathodes were the first employed for lithium laboratory cells, their use in practical batteries was abandoned primarily due to the insulating nature of those materials, which necessitates using high temperatures in order to facilitate mass transport within the cathodes.
  • Conducting polymers are polymers through which electrons can move from one end of the polymer to the other.
  • a conducting polymer transports voltage and/or current along its backbone or between its chains by changing the distribution of electrons in the polymer chain.
  • Such conduction typically occurs through conjugated ⁇ electronic functionalities, although some conducting polymers include other types of electronic functionalities.
  • conductivity occurs in short chains of the polymer ("oligomers"). In some cases, conductivity occurs in long chains of the polymer.
  • Non-limiting examples of conducting polymers include poly(acetylene), poly(aniline). poly(pyrrole), poly(thiophene), poly(/7-phenylene), (poly)phthalocyanine, etc. and derivatives thereof.
  • a redox species is an atom, molecule, or macromolecule that accepts or releases one or more electrons when placed under an electric field of appropriate direction and magnitude.
  • Non-limiting examples of redox species include ruthenium hexamine chloride, ferrocene, gold, poly(pyrrole). hexanethiol. and similar species and derivatives.
  • a battery is comprised of one or more cells each comprised of an electropositive anode such as lithium or nickel, an electronegative cathode such as metal oxide, sulfur, or cadmium, and an ionically-conducting separator, such as poly(ethylene oxide), propylene carbonate, or Nafion. that contain an electrolytic salt such as lithium hexafluorophosphate, sodium chloride, etc.
  • a cell "discharges" by allowing electrons to pass via an external circuit from a higher energy state in the anode to a lower energy state in the cathode while allowing ions to pass through the separator.
  • Li ions pass from the anode through the separator to the cathode.
  • the electrons that pass through the external circuit may be used to perform work. In a rechargeable battery, this electron and ion movement may be reversed to some extent by applying an external current to the cell to "charge" the cell.
  • the typical forms of batteries, and more specifically of lithium-based batteries are well known to those skilled in the art.
  • sulfur species include atoms, molecules, and macromolecules that contain at least one sulfur atom. Typical terms used to describe such molecules include organosulfur. sulfur, sulfide. disuifide. thio. thiol, thiolate, mercapto. mercaptan. etc.
  • the sulfur species contains a negatively-charged or proton-associated sulfur atom that is covalently bound to another atom through a single bond. This type of sulfur species is capable of releasing an associated cation or proton and forming a disuifide bond with a similar atom.
  • the sulfur species contains sulfur atoms that are multiply bound to other atom or atoms and are not capable of forming disuifide bonds.
  • sulfur species refers to atoms, molecules, and macromolecules that contain at least one sulfur atom that can act in part or in whole as a redox species.
  • selenium species include atoms, molecules, and macromolecules that contain at least one selenium atom. Typical terms used to describe such molecules include selenide. selenate. diselenides. etc.
  • the selenide species contains a negatively-charged or proton-associated selenide atom that is covalently bound to another atom through a single bond. This type of selenide species is capable of releasing an associated cation or proton and forming a diselenide bond with a similar atom.
  • the selenide species contains selenide atoms that are multiply bound to other atom or atoms and are not capable of forming diselenide bonds.
  • selenide species refers to atoms, molecules, and macromolecules that contain at least one selenide atom that can act in part or in whole as a redox species.
  • the cathode materials of concern are the conducting polymer or backbone and the redox active species or sulfur species.
  • the selection of the materials is based on the characteristics of the materials relating to the other components of the batteries and to each other.
  • the selection of cathode materials is based on one or more of the following characteristics of the conducting polymer and/or the sulfur or selenide species: ease of fabrication using straightforward synthetic procedures; ionically conductive for Li + ions; no labile protons in the material; a high density of electroactive species per weight and volume (i.e.
  • the selection of the cathode materials is based on all of the above identified characteristics for both the conducting polymer and the sulfur or selenide species.
  • the selection of cathode materials is based on the overlap of the thermodynamic potentials of the electroactive substituents of the sulfur species and the conducting polymer.
  • the cathode materials are chosen based on the redox mediation window.
  • the conducting polymer mediates electrons between the current collector and the sulfur or selenium species. Conducting polymers exhibit potential-dependent conductivities. When the potential is in the "double-layer" region of the conducting polymer (that is, when the conducting polymer is releasing or accepting electrons), the conductivity of the polymer is much higher than when the potential is more negative or more positive of that region.
  • the conducting polymer is inherently in a less-conductive state in the potential region where the sulfur or selenium species exhibits redox species behavior, mediation of electrons between the current collector and the sulfur or selenium species is poorly effected, the material is less desirable, and the battery performance is poorer.
  • the resulting premise of the selection process of materials is that the redox active species or sulfur species that are mobile are not compatible with long- life, high-capacity batteries.
  • Another aspect of the present invention pertains to resultant cathode materials identified by the use of the selection process identified above.
  • the cathode materials were selected because they exhibit overlap of the thermodynamic potentials of the electroactive substituents of the sulfur species and the conducting polymer.
  • the cathode materials form a redox mediation window.
  • the conducting polymer mediates electrons between electrode(s) and the sulfur species in an effective fashion.
  • the sulfur species is NOT covalently linked to the conducting polymer backbone.
  • An example of this system is that comprising a mixture of poly(3.4-ethylenedioxythiophene) (PEDT) and 2.5-dimercapto-l ,3,4-thiadiazole. dilithium salt (Li 2 DMcT).
  • PEDT poly(3.4-ethylenedioxythiophene)
  • dilithium salt Li 2 DMcT
  • PEDT is available as an aqueous dispersion. Li 2 DMcT is dissolved directly into the PEDT dispersion at high concentrations. Properly treated films cast from that mixture are used as cathode materials in lithium and lithium-ion cells.
  • films are prepared by electrochemical or chemical oxidation of the PEDT monomer and Li 2 DMcT from the same or different solutions in a homogeneous or layered arrangement.
  • Li 2 DMcT contains no labile protons, so its use in the cathode is attractive.
  • PEDT has a wide potential window of conductivity, contains no labile protons, and is not proton-doped, so its use in the cathode is attractive.
  • the cathode materials are not mobile. Specifically, the redox active species or sulfur species is not mobile. The redox active species is bound to the conducting polymer and is not able to migrate from the conducting polymer.
  • the cathode material is a single component sulfur-based conducting polymer with the sulfur species covalently linked to the conducting polymer.
  • the link of the sulfur species and the conducting polymer provides suitable fade characteristics by not allowing the sulfur species to be soluble in the electrolyte.
  • sulfur or other sulfur species apart from the covalently linked sulfur species may or may not be present.
  • the cathode material contains no other sulfur or sulfur species apart from the bound sulfur species.
  • the cathode material is a thiophene based polymer with covalently linked sulfur species.
  • Such conducting polymers have been covalently-derivatized with sulfides and/or sulfide-containing groups and employed as battery cathode materials. Physical constraints of the conducting polymer and sulfide components via covalent bonds which are present regardless of charge state of the cathode represents a novel step in the field.
  • Yet another aspect of the present invention pertains to a method of synthesis of the selected cathode material.
  • Still another aspect of the present invention pertains to batteries which comprise an anode: cathode material(s) of the present invention, as described herein; and a separator between the anode and the cathode materials
  • Fig. 1 shows a sulfur cathode in operation by storing energy as a disuifide bridge then releasing it by reducing to thiolate moieties.
  • Fig. 2 shows an example of an inappropriate overlap of thermodynamic potentials between polyaniline and an organosulfur.
  • Fig. 3 shows a general formula of a conducting polymer of the present invention.
  • Fig. 4 shows a more specific formula of the present invention.
  • Fig. 5 shows the substituent parts of the polythiophene conducting polymer.
  • Fig. 6 shows two resultant conducting polymers of the present invention.
  • the cathode materials of concern are the conducting polymer or backbone and the redox active species or sulfur species.
  • the selection of the materials is based on the characteristics of the materials relating to the other components of the batteries and to each other.
  • the selection of cathode materials is based on one or more of the following characteristics of the conducting polymer and/or the sulfur species: ease of fabrication using straightforward synthetic procedures; ionically conductive for Li + ions; no labile protons in the material; a high density of electroactive species per weight and volume; good overlap of the thermodynamic potentials of the electroactive substituents and conducting polymer backbone; reasonable electronic conductivity of the composite; no solubility in typical electrolyte solutions; and electrochemically stable to many repeated charge and discharge cycles.
  • the selection of the cathode materials is based on all of the above identified characteristics for both the conducting polymer and the sulfur species. Molecular design of innovative sulfur-based cathode materials
  • cathode materials The chemical and physical constraints imposed on cathode materials are substantial. The specific properties required include ease of fabrication using straightforward synthetic procedures.
  • the sulfur species and preferably the conducting polymer must be ionically conductive for Li + ions.
  • the chemistry of sulfur-based batteries necessitates the requirement of the cathode materials to be ionically conductive for Li + ions.
  • a material that contains mobile redox species presents stability, capacity fade, and safety problems when used as a cathode material in a lithium or lithium-ion or lithium polymer cell.
  • 2,5-dimercapto-l,3,4-thiadiazole contains two labile protons.
  • Use of that material as a component of a cathode material leads to transport of the labile protons via intermediate species into the electrolyte and eventually to the anode, where spontaneous electrochemical reduction by the anode creates hydrogen gas. Similar events can occur when poly(aniline), a proton-doped conducting polymer, is used as a component of a cathode material.
  • This constraint includes the selection of conducting polymers and sulfur species that do not contain labile protons at any stage of the battery reaction.
  • a battery ' s effectiveness is attributable to the charge capacity. Selecting a sulfur species and conducting polymer with a high density of electroactive species per weight and volume (i.e. large inherent charge capacity) increases the effectiveness of the cathode and battery overall.
  • a battery ' s effectiveness is also dependent on the electronic conductivity of the cathode materials. Selecting a sulfur species and conducting polymer with an electronic conductivity above 10 " ° S/cm. more preferably above 10 "5 S/cm. more preferably above 10 " S/cm, more preferably above 10 " S/cm. and most preferably above 10 " S/cm increases a battery's effectiveness.
  • the solubility of the sulfur species or conducting polymer in the electrolyte inhibits the efficiency of the battery.
  • sulfur species or other electroactive species associated with the conducting polymer are mobile in the electrolyte, the species may migrate towards the anode and a decrease in efficiency results when the species contact the anode. Over time the anode increasingly becomes contacted with species and a loss of electroactive sites may be seen on the anode.
  • the solubility of the sulfur species also leads to collection of the active sulfur away from the conducting polymer and therefore a loss of redox species in the cathode.
  • selecting sulfur species and conducting polymers which are not soluble in the electrolyte solution increases the efficiency of the battery and reduces the fade and poor cyclability typical of sulfur-based batteries.
  • the current sulfur-based batteries in use exhibit considerable fade over even 100 cycles. Many factors contribute to the fade observed in conventional sulfur-based batteries. However, by selecting the conducting polymer and sulfur species of the cathode materials that are electrochemically stable to many repeated charge and discharge cycles the fade is reduced.
  • the selection of cathode materials is based on the overlap of the thermodynamic potentials of the electroactive substituents of the sulfur species and the conducting polymer.
  • the cathode materials are chosen based on the redox mediation window.
  • the conducting polymer mediates electrons between electrode and sulfur species.
  • thermodynamic potentials An example of inappropriate overlap of thermodynamic potentials, the redox response of composite cathode components are shown in Figure 3. While oxidation of the organosulfur occurs when the polyaniline is primarily in its metallic state (indicated by a dashed line at 3.1 V). reduction of the resulting disuifide occurs in a potential window where the polyaniline is primarily in its insulating state (indicated by a dashed line at 2.6 V). The practical consequences of that thermodynamic mismatch between components is apparent in devices using such cathodes - charging of the cells occurs quickly, but discharging is slow and typically incomplete.
  • Another aspect of the present invention pertains to resultant cathode materials identified by the use of the selection process of the present invention.
  • the cathode materials were selected because they exhibit overlap of the thermodynamic potentials of the electroactive substituents of the sulfur species and the conducting polymer.
  • the cathode materials form a redox mediation window.
  • the conducting polymer mediates electrons between electrode(s) and the sulfur species.
  • the resulting premise of the selection process of materials is the redox active species or sulfur species that are mobile are not compatible with long-life, high-capacity batteries.
  • the sulfur species in the cathode materials is not mobile and is not soluble in the electrolyte of the battery and does not include labile protons that are mobile or soluble in the electrolyte. More preferentially, the cathode materials are not mobile.
  • the redox active species or sulfur species is not mobile.
  • the redox active species is bound to the conducting polymer and is not able to migrate from the conducting polymer.
  • the cathode material is a single component sulfur-based conducting polymer with the sulfur species covalently linked to the conducting polymer.
  • the link of the sulfur species and the conducting polymer provides suitable fade characteristics by not allowing the sulfur species to be soluble in the electrolyte.
  • sulfur or other sulfur species in the cathode apart from the covalently linked sulfur species may or may not be present.
  • the cathode material contains no other sulfur or sulfur species apart from the bound sulfur species.
  • the cathode material is a thiophene based polymer (such as polythiophene) with covalently linked sulfur species.
  • thiophene based polymer such as polythiophene
  • Such conducting polymers have been covalently-derivatized with sulfides and/or sulfide-containing groups as battery cathode materials. Physical constraints of the conducting polymer and sulfide components via covalent bonds which are present regardless of charge state of the cathode represents a novel step in the field.
  • a resultant cathode material was identified.
  • Sulfur-derivatized conducting polymers based on the oxide-substituted poly(thiophene) backbone are synthesized. Those polymers show good thermodynamic overlap with sulfide oxidation and reduction (i.e. charge and discharge). Covalent linkage of the sulfur groups to the backbone provides molecular-level ordering of the material, effecting homogeneous conductivity, cycling stability, and physical structure of the cathode.
  • the sulfur-derivatized conducting polymers have the general formula (R,) n (YjA ) m where R is monomer or oligomer units of a conducting polymer, i is 1 to n and n is greater than 20. more preferably greater than 100. more preferably greater than 1000. more preferably greater than 10.000 and most preferably greater than 100.000: Y is a functionalizing group that provides additional physical or chemical properties to the conducting polymer and j is 0 to n; A is a sulfur species, k is 1 to n and m is 1 to 12.
  • R is monomer or oligomer units of a conducting polymer
  • i 1 to n and n is greater than 20. more preferably greater than 100. more preferably greater than 1000. more preferably greater than 10.000 and most preferably greater than 100.000:
  • Y is a functionalizing group that provides additional physical or chemical properties to the conducting polymer and j is 0 to n;
  • A is a sulfur species, k is 1 to n
  • the sulfur-derivatized conducting polymers have the general formula (R) n (YS m ) x where R is a conducting polymer backbone and n is greater than 20, more preferably greater than 100, more preferably greater than 1000, more preferably greater than 10,000 and most preferably greater than 100,000; Y is a functionalizing group; S is an organosulfur moiety, m is 1 to 12 and x is 1 to 4.
  • R is polythiophene or its derivatives. The formula is shown in figure 4. The preferred embodiment is shoiwn in figure 5 based on the polythiophene backbone R n .
  • the present invention also concerns covalently derivatizing an electronically conducting polymer with a high density of electroactive sulfur species.
  • the materials operate near the high oxidation potentials exhibited by the more common metal oxide cathodes but show far better ionic conductivity. This is accomplished by applying preexisting, high yield organic synthesis procedures to the formation of monomeric. and then polymeric species composed of thiophene-based polymer chains with thiolate substituents. The synthesis steps are geared toward forming a reasonably high molecular weight polymer while at the same time incorporating a high density of electroactive species that are not only electrochemically stable, but also protect the polymer from chemical degradation.
  • Another aspect of the present invention pe ⁇ ains to a method of designing conducting polymers covalently-derivatized with sulfur species such that the chemical, physical, and electrochemical properties of the designed material are advantageous to use in a rechargeable cell.
  • the conducting polymers represented by Figure 6. the number of carbon atoms between the oxygen atoms and the sulfide-containing six-membered ring are varied to affect both the proximity of the sulfide-containing six-membered ring to the conducting polymer backbone and the flexibility of the attachment of the sulfide-containing six-membered ring.
  • other atom or functional groups such as sulfur, selenium, amides, amines, etc.
  • the number of carbon atoms in the sulfide-containing six-membered ring are reduced or increased in order to affect the electronic, physical, or chemical properties of the sulfur atoms. For instance, reducing the number of carbon atoms to produce a sulfide-containing four-membered ring causes additional strain on the disuifide oxidation product and results in higher potentials for redox activity of that sulfur species.
  • additional substituents are placed on the conducting polymer ring, functionalizing group, or sulfur species in order to affect the chemical and physical properties of the material. For instance, attaching a alkylsulfonate at the carbon atom above the oxygen atom increases the solubility and miscibility of the material.
  • Yet another aspect of the present invention pertains to a method of synthesis of the selected cathode material.
  • Still another aspect of the present invention pertains to batteries which comprise an anode; cathode material(s) of the present invention, as described herein; and a separator between the anode and the cathode materials.
  • a battery with the cathode material as sulfur- derivatized conducting polymers based on the oxide-substituted poly( thiophene) backbone are used as a substitute cathode in existing lithium, lithium-ion. and lithium polymer rechargeable batteries.
  • Two thiophene-based polymers, structures shown in Figure 6. were synthesized.
  • the first (PDDT) follows a tractable route to produce a material with an attractive theoretical specific capacity (235 A h kg).
  • Synthesis of the second polymer (PDPT) was more uncertain due to its bulky substituents, yet its synthesis yielded a material with a very attractive theoretical specific capacity (332 A h/kg).
  • PDDT was chosen as a cathode material in part because a stable 6-member ring is formed during oxidation to the disuifide. ->->
  • Processing of conducting polymers is a non-trivial issue - the very traits that make those materials conductive also result in low solubility of the polymers in most solvent systems. That problem is compounded for the systems described herein by the typically poor solubility of sulfide species.
  • a saturated solution is directly cast onto the current collector. Care was taken to generate uniformly small particle sizes of the polymer prior to deposition. Evaporation of the solvent under normal drying conditions leads to a relatively adherent film due to the soluble phase acting as a binder. If a quality film is generated, but adhesion to the current collector is poor, then the current collector is chemically or mechanically treated prior to film deposition.
  • a non-protic solvent such as N-methylpyrrolidinone or methylene chloride
  • the derivatized conducting polymer is prepared by chemical or electrochemical oxidation of its monomer in the presence of a suitable current collector.
  • the monomer of PDDT ( Figure 6) is electrochemically oxidized at a stainless steel electrode by applying a potential of more than one volt versus the Ag/AgCl reference redox couple. This application results in the preparation of a film of PDDT on the stainless steel suitable for use as a cathode material.
  • carbon paste electrodes containing the polymers are prepared in order to allow electrochemical testing of their properties.
  • 3.4-dihydroxythiophene can be synthesized by adding 2.2'- thiobisacetate ethyl ester to diethyl oxalate in a solution of ethanol and sodium metal, according to the method of Hinsberg, to produce 3.4-dihydroxy-2.5- dicarbethoxythiophene.
  • compound A in Scheme 3 Hydrolysis of compound A with ethanolic sodium hydroxide results in a dicarboxylic acid, compound B. Heating compound B under a reduced atmosphere causes sublimation of compound C as a yellow powder. Care must be taken in isolation because compound C decomposes readily on exposure to heat, light and moisture.
  • 3.4-dihydroxythiophene is to add HS " and a base, or simply S 2" . to 1,4- dibromo-2.3-butanedione.
  • HS " and a base or simply S 2" .
  • 1,4- dibromo-2.3-butanedione 1,4- dibromo-2.3-butanedione.
  • compound D 2 equivalents of ethyl bromoacetate under basic conditions
  • compound F can be synthesized by adding 3,4- dihydroxythiophene to a cyclic sulfate ethyl ester, compound E, in the presence of potassium tcrt-butoxide at elevated temperatures.

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Abstract

L'invention concerne la sélection de matériaux pour cathodes. Les matériaux pour cathodes de l'invention se présentent comme un polymère conducteur ou un squelette et des espèces actives rédox ou des espèces de soufre. La sélection de matériaux se fait en fonction des caractéristiques de matériaux liées aux autres composants des piles et les unes aux autres. La présente invention concerne aussi des matériaux pour cathodes obtenus, notamment un matériau pour cathode sélectionné constitué d'un polymère conducteur à base de soufre à composant unique avec des espèces de soufre liées par covalence au polymère conducteur; elle concerne plus précisément un polymère à base de thiophène avec des espèces de soufre liées par covalence. Les polymères conducteurs ont été dérivés par covalence avec des sulfures et/ou des groupes sulfurés utilisés comme matériaux pour cathodes. L'invention concerne enfin une pile utilisant le procédé de sélection et les matériaux pour cathodes obtenus.
EP00907101A 1999-02-01 2000-01-31 Cathodes a base de soufre a composant unique destinees aux piles a lithium et ion-lithium Withdrawn EP1179220A2 (fr)

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US11806899P 1999-02-01 1999-02-01
US118068P 1999-02-01
PCT/US2000/002445 WO2000045451A1 (fr) 1999-02-01 2000-01-31 Cathodes a base de soufre a composant unique destinees aux piles a lithium et ion-lithium

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PL370509A1 (en) * 2002-02-07 2005-05-30 Noboru Oyama Redox active reversible electrode and novel cell using it
DE102007062282A1 (de) * 2007-12-21 2009-06-25 Saltigo Gmbh Verfahren zur Herstellung von Thiodiglycolsäuredialkylestern
JP6753191B2 (ja) * 2016-07-27 2020-09-09 東ソー株式会社 チオフェン化合物
CN110380052B (zh) * 2019-07-19 2022-05-17 东营昆宇电源科技有限公司 一种基于锂硫电池正极用高导电硫基复合材料

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US4472488A (en) * 1983-11-30 1984-09-18 Allied Corporation Polymeric electrode coated with reaction product of cyclic compound
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US5723230A (en) * 1995-02-27 1998-03-03 Yazaki Corporation Oligosulfide type electrode material and secondary battery containing such electrode material
DE19522263C2 (de) * 1995-06-20 1998-07-09 Zeiss Carl Jena Gmbh Referenzinterferometer (RI) mit variabler Wellenlänge

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