KR20150043407A - Composite materials for lithium-sulfur batteries - Google Patents

Abstract

The present invention relates to a process for the production of at least one carbon composite material (A) comprising at least one carbonaceous starting material (a) comprising at least one particle (aa) of an electrically conductive additive having an aspect ratio of 10 or more, B). ≪ / RTI > The present invention also relates to a method for producing a sulfur-carbon composite material of the present invention, a cathode material for an electrochemical cell including the sulfur-carbon composite material of the present invention, a corresponding electrochemical cell, Lt; / RTI >

Description

[0001] COMPOSITE MATERIALS FOR LITHIUM-SULFUR BATTERIES [0002]

The present invention relates to a process for the production of at least one carbon composite material (A) comprising at least one carbonaceous starting material (a) comprising at least one particle (aa) of an electrically conductive additive having an aspect ratio of 10 or more, B). ≪ / RTI >

The present invention also relates to a method for producing a sulfur-carbon composite material of the present invention, a cathode material for an electrochemical cell including the sulfur-carbon composite material of the present invention, a corresponding electrochemical cell, To the use for the manufacture of batteries.

Storing energy has long been a target of interest. An electrochemical cell, such as a battery or a battery, can be used to store electrical energy. Recently, what is called a lithium ion battery is attracting particular attention. This is superior to conventional batteries in several technical aspects. For example, it can be used to generate a voltage that can not be obtained with a battery based on an aqueous electrolyte.

However, the energy density of conventional lithium ion capacitors having a cathode based on carbon anodes and metal oxides is limited. A new dimension related to energy density is being opened by lithium-sulfur batteries. In a lithium-sulfur battery, sulfur is reduced to S ^{2 -} through the polysulfide ion in the sulfur cathode, which again oxidizes when the cell is charged to form sulfur-sulfur bonds. During the charging and discharging operations, the structure of the cathode is correspondingly changed, which corresponds to the expansion and contraction of the cathode, i.e., the volume, at the macroscopic level.

In addition to sulfur, cathodes in lithium-sulfur batteries typically also include carbon black or a mixture of carbon black and a binder as a conductive additive. The binder typically present in the cathode of a lithium-sulfur battery is primarily contacted with electrically conductive carbon black particles and an electrochemically active sulfur (which itself is not electrically conductive) and, secondly, a sulfur- To the output material of the cathode (e.g., metal foil, metal mesh, or metal-coated polymer film).

WO 2009/054987 describes polyvinyl alcohol as a primer layer on an aluminum layer provided as a conductor (also referred to as a current collector) for a sulfur cathode.

US 2010/0239914 and US 2011/0059361 prepare cathodes for lithium-sulfur batteries by combining sulfur and soot particles with polyvinyl alcohol in each case using polyvinyl alcohol as the binder.

The sulfur-containing cathode materials described in this document still have disadvantages associated with one or more of the desirable physical properties for cathode materials and electrochemical cells made therefrom. Preferred physical properties include, for example, good adhesion properties of the cathode material to the output material, high electrical conductivity of the cathode material, increase in the cathode capacity, increase in the lifetime of the electrochemical cell, improvement in the mechanical stability of the cathode, Reduction of the volume change of the cathode during the charge-discharge cycle. In general, the above-mentioned desirable properties also make a decisive contribution to improving the economics of the electrochemical cell, which is of crucial importance to the user as well as the desired technical performance profile aspect of the electrochemical cell.

It is therefore an object of the present invention to provide an inexpensive cathode material for a lithium-sulfur battery, more particularly having a high cathode capacity, a high mechanical stability and a long lifetime, which has a further advantage in the properties of one or more of the known cathode materials And to provide a cathode material that enables the production of a cathode with improved electrical conductivity.

The above-

(aa) particles of at least one electrically conductive additive having an aspect ratio of 10 or greater

(A) at least one carbonized product of the carbonaceous starting material

(A) at least one carbon composite material and

(B) Elemental sulfur

≪ / RTI >

The sulfur-carbon composite material of the present invention is a composite material. Composite materials are generally understood to mean materials that are not manually separable and are a solid mixture with discrete components and other physical properties. Specifically, the sulfur-carbon composite material of the present invention is a particulate composite material, particularly a fibrous composite material.

The sulfur-carbon composite material of the present invention comprises as component (A) at least one carbon composite material (hereinafter also simply referred to as carbon composite (A)), which comprises as component (a) Wherein the component (a) further comprises, as component (aa), particles of at least one electrically conductive additive having an aspect ratio of 10 or more (hereinafter also referred to simply as particles (a) aa "). Further, the sulfur-carbon composite material of the present invention contains elemental sulfur (hereinafter simply referred to as sulfur (B)) as the component (B).

The carbonized product (a) present in the carbon composite (A) (which is a solid) can be produced from various carbonaceous starting materials. Suitable carbonaceous starting materials for the preparation of carbonized products and their use in such manufacturing processes are basically known to those skilled in the art. The carbonized product typically pyrolyzes the carbonaceous starting material, while heating to provide complete or at least substantially complete elimination of oxygen, as much as possible to prevent oxidation of the carbon from the starting material to carbon monoxide or carbon dioxide, Carbon-rich residue. Carbonization products from the pyrolysis process are known, for example, carbon black formed from wood charcoal, animal charcoal, brown coal or hard coal, or polyacrylonitrile. The carbonization product (a) may also be referred to as a carbon matrix obtainable by pyrolysis of the elastomeric starting material.

The elastomeric starting material is preferably selected from carbohydrates, resins, coke, pitch, polyacrylonitrile, styrene-acrylonitrile copolymers, melamine-formaldehyde resins and phenol-formaldehyde resins. Preferred elastoplastic starting materials are in particular carbohydrates, especially mono-, di- or polysaccharides, where typically only water is removed leaving behind carbon. The carbohydrate is most preferably starch.

In one embodiment of the present invention, the sulfur-carbon composite material of the present invention is characterized in that the carbonaceous starting material is a carbohydrate, a resin, a coke, a pitch, a polyacrylonitrile, a styrene- acrylonitrile copolymer, a melamine- Aldehyde resins and phenol-formaldehyde resins, especially carbohydrates.

The carbon content in the carbonized product (a) is preferably more than 80% by weight, more preferably more than 90% by weight, especially more than 95% by weight, The maximum is about 100% by weight.

(Aa) present in the carbon composite (A) has an aspect ratio of 10 or more, preferably 20 or more, more preferably 40 or more, especially 80 or more. The aspect ratio of the particles is understood to mean the ratio of the length of the particles to the thickness of the particles. Particles having an aspect ratio of 10 or more can thus take the form of fibers or leaflets.

The particles (aa) of the at least one electrically conductive additive are preferably fibrous, in which case the thickness of the fibers is better called their diameter.

The length and diameter of the particles, especially the fibers, are determined by scanning electron microscopy or optical microscopy. The aspect ratio is calculated using the thus determined value.

The thickness or average diameter of the particles of the electrically conductive additive can vary basically in a wide range. The particles of the electrically conductive additive preferably have a thickness in the range from 50 nm to 100 μm, more preferably in the range from 60 nm to 1000 nm, in particular in the range from 70 to 200 nm, or even more particularly an average diameter.

The average diameter of the particles is determined by a scanning electron microscope or an optical microscope as described above.

In one embodiment of the present invention, the sulfur-carbon composite material of the present invention is characterized in that the particles of the electrically conductive additive have an average diameter in the range of 50 nm to 100 mu m.

The particles of the electrically conductive additive preferably have an electrical conductivity in the range of from 0.1 mS / cm to 30,000 S / cm, more preferably from 100 mS / cm to 30,000 mS / cm.

The electrical conductivity LF of the additive is determined by pressing the additive in a standard press mold such as that used in the manufacture of KBr discs to provide a pellet with thickness d and cross- The pellet is then clamped between two gold metal plates and analyzed by electrical impedance spectrophotometry. The electrical conductivity LF is calculated according to the equation LF = d / (A x Re) using a substantial portion Re of the impedance (in the high frequency range of 1 to 10 kHz).

In one embodiment of the present invention, the sulfur-carbon composite material of the present invention is characterized in that the particles of the electrically conductive additive have electrical conductivity in the range of 0.1 mS / cm to 30,000 S / cm.

Suitable electrically conductive additive particles are basically known to those skilled in the art. The electrically conductive additive particles are preferably carbon fibers; A fiber of a transparent metal oxide selected from indium tin oxide, Al-doped zinc oxide, Ga-doped zinc oxide, In-doped zinc oxide, F-doped tin dioxide, and Sb-doped tin dioxide; Fibers of metal carbides selected from WC, MoC and TiC; And metal fibers selected from aluminum and steel. The electroconductive additive particles are more preferably carbon fibers.

Methods for making electrically conductive additive particles, particularly electrically conductive additive fibers, are known to those skilled in the art. For example, it is possible to obtain carbon fibers by pyrolysis of polyacrylonitrile fibers. Carbon fibers are commercially available from many sources. Transparent metal oxide fibers, for example Al-doped zinc oxide or fibers of Sb-doped tin dioxide, can be produced by an electrical spinning process and subsequent sintering, for example as described in WO2010 / 122049 or WO2011 / 054701 .

In one embodiment of the present invention, the sulfur-carbon composite material of the present invention is characterized in that the particles of the electrically conductive additive are carbon fibers; A fiber of a transparent metal oxide selected from indium tin oxide, Al-doped zinc oxide, Ga-doped zinc oxide, In-doped zinc oxide, F-doped tin dioxide, and Sb-doped tin dioxide; Fibers of metal carbides selected from WC, MoC and TiC; And metal fibers selected from aluminum and steel.

The weight ratio of the electrically conductive additive particles based on the total weight of the sulfur-carbon composite material (A) may vary within a wide range. The weight ratio of the particles of the electrically conductive additive based on the total weight of the sulfur-carbon composite material (A) is preferably 0.1 to 60 wt%, more preferably 1 to 40 wt%, particularly preferably 5 to 25 wt% to be.

In one embodiment of the present invention, the sulfur-carbon composite material of the present invention is characterized in that the weight ratio of the particles of the electrically conductive additive based on the total weight of the sulfur-carbon composite material (A) is 0.1 to 60 wt% Range.

In a preferred embodiment, the sum of the total weight of the carbonized product (a) and the electrically conductive additive particles (aa) in the carbon composite (A) is at least 80 wt%, more preferably at least 90 wt%, especially at least 95 wt% Is almost 100% by weight. The weight ratio can be determined by the element analysis means in consideration of the chemical composition of the starting component.

In a further embodiment, the carbon composite material (A) has an average particle diameter in the range of 70 to 200 nm, an aspect ratio of 10 or more, and a sum of the weight ratios of the carbonization product (a) used and the carbon fibers used as the particles (A), which is a carbonization product of a polysaccharide (particularly starch) comprising particles (aa) of at least one electrically conductive additive comprising carbon fibers in the range of from 95 wt% to 100 wt% .

The carbon content in the carbon composite (A) is preferably more than 80% by weight, more preferably more than 90% by weight, particularly more than 95% by weight, and most preferably more than 95% by weight, based on the mass of the carbon composite (A) Is almost 100% by weight.

The sulfur-carbon composite material of the present invention contains elemental sulfur as component (B), and elemental sulfur is known per se.

The sulfur in the carbon composite (A) is preferably finely and homogeneously distributed. The average particle size of sulfur is in the range of 0.1 to 50 mu m, preferably in the range of 0.1 to 25 mu m, more preferably in the range of 0.1 to 10 mu m. The average particle size of sulfur in the sulfur-carbon composite material can be measured by a scanning electron microscope.

The weight ratio of sulfur based on the sum of the weight ratios of the carbon composite material (A) and sulfur (B) may vary within a wide range. Carbon composite material and sulfur is in the range of 10 to 95 wt.%, More preferably 30 to 90 wt.%, Especially 50 to 85 wt.%, As determined by elemental analysis, based on the total weight ratio of sulfur.

In one embodiment of the present invention, the sulfur-carbon composite material of the present invention is characterized in that the weight ratio of sulfur based on the total weight ratio of the carbon composite material and sulfur is 10 to 95% by weight.

Carbon composite material (A) or the sulfur-carbon composite material of the present invention may be obtained in different forms depending on each manufacturing process. Depending on the reactor size used, it is basically possible to produce a shaped body with a spatial dimension in the range of 0.001 m to 1 m, i.e. a shaped body having a volume in the range of 10 ^-9 m ³ to 1 m ³ . (A) having an average particle diameter in the range of 10 nm to 1000 mu m, preferably in the range of 100 mu m to 10 mu m, more preferably in the range of 0.1 to 10 mu m by a known grinding technique such as grinding, It is possible to prepare particles or the sulfur-carbon composite material particles of the present invention. Such finely divided powders composed of fine particles are particularly preferred in the present invention.

In one embodiment of the present invention, the sulfur-carbon composite material of the present invention is characterized in that the sulfur-carbon composite material is in a particulate form.

The above-described sulfur-carbon composite material of the present invention can be produced in a different manner. The process for preparing the sulfur-carbon composite material of the present invention preferably comprises mixing the mixture comprising at least one elastomeric starting material and at least one electrically conductive additive particle (having an aspect ratio of 10 or more) with each other, And mixing. To ensure this, the starting material for the preparation of the carbon composite (A) is preferably in the form of a powder which can be mixed normally without any problem. Alternatively, the mixing may be carried out, for example, in a mixer (also referred to as a blender), a mill or an extruder, depending on the type and physical properties of the starting material. The mixing step may preferably be performed with or without the addition of a suitable liquid which can be removed without any problems in the subsequent carbonization step.

In a further process step, the mixture comprising the carbonaceous starting material and the electrically conductive additive particles is converted to a carbon composite (A) by carbonization, and the carbonaceous starting material forms a carbonized product.

In a further process step, the carbon composite material is mixed with elemental sulfur, possibly after the milling step. Carbon composite material and a sulfur (preferably a sulfur powder).

The present invention also relates to a process for the production of at least one carbon composite material (A) comprising at least one carbonaceous starting material (a) comprising at least one particle of electrically conductive additives (aa) and having an aspect ratio of 10 or more, (B), characterized in that it comprises at least

(i) preparing a mixture comprising at least one elastomeric starting material, and particles of at least one electrically conductive additive having an aspect ratio of at least 10,

(ii) carbonizing said elastomeric starting material to form a carbonized product comprising electrically conductive additive particles to provide a carbon composite material; and

(iii) preparing a mixture of elemental sulfur and the carbon composite material obtained in step (ii)

.

Descriptions and preferred embodiments of the elastomeric starting material, particles (aa), carbonized product (a), carbon composite material (A) and elemental sulfur (B) in the process according to the present invention are the sulfur- Corresponding to the above description of these components for the substance.

In process step (i), as described above, a homogeneous mixture of starting components for the carbon composite material (A) is preferably added to the carbon composite material (A) in the presence of a further auxiliary agent (e.g. water) which is pyrolyzable or completely removable in the carbonization step With or without the addition of a solvent.

In process step (ii), carbon composite material (A) is produced by carbonizing a mixture containing the particles of the carbonaceous starting material and the electrically conductive additive, and the carbonaceous starting material is converted to carbonization product (a). (Ii) a step of heat-treating the mixture of starting materials at a temperature of less than 200 ° C (which may be, for example, in the case of a wet starch, for gluing or for removal of one or more solvents, Drying step) may be preceded by one or more.

The term "carbonizing" or "carbonization" is used herein as a synonym.

In general, the carbonization is carried out at a temperature in the range of 200 to 2000 ° C, preferably in the range of 300 to 1600 ° C, more preferably in the range of 400 to 1100 ° C, in particular in the range of 500 to 900 ° C.

In one embodiment of the present invention, a feature of the process according to the invention of the sulfur-carbon composite material is that the carbonization in process step (ii) is carried out at a temperature of at least 500 ° C, in particular in the range of from 550 to 700 ° C.

The duration of the carbonization can vary over a wide range and depends on factors including the temperature at which carbonization is carried out. The carbonization period may be 0.5 to 50 hours, preferably 1 to 24 hours, particularly 2 to 12 hours.

The carbonization of the mixture comprising the elastomeric starting material and the particles (aa) can basically be carried out in one or more stages, for example in one stage or two stages. Basically, the carbonization step can be carried out in the presence or absence of an oxidizing agent, for example oxygen, with the proviso that the oxidizing agent does not completely oxidize the carbon present in the elastomeric starting material. It has been found to be advantageous to carry out carbonization in the presence of an inert gas, preferably under inert or substantially complete elimination of oxygen, in order to very substantially inhibit the oxidation of the carbon present in the elastomeric starting material.

The carbonization of the mixture comprising the elastoplastic starting material and the particles (aa) can be carried out basically under reduced pressure, for example under vacuum, under standard pressure, or under elevated pressure, for example in a pressurized autoclave. In general, the carbonization is carried out at a pressure in the range of 0.01 to 100 bar, preferably 0.1 to 10 bar, especially 0.5 to 5 bar or 0.7 to 2 bar. The carbonization can be carried out with a closed system or an open system, where the volatile components produced are removed into a gaseous stream, an inert gas or a reducing gas.

In the process step (iii), a mixture of the carbon composite material (A) and the elemental sulfur (B) obtained in the step (ii) is produced. As described above, for this purpose, it is preferable to prepare a homogeneous mixture of the carbon composite material (A) and sulfur. The components (A) and (B) may be pulverized either independently or directly together to provide a powder. In order to obtain a sulfur-carbon composite material from the mixture of the components (A) and (B), the mixture is preferably heat-treated. Particularly preferred is to heat the components (A) and (B) together at a temperature in the range of from 100 to 200 占 폚. Process step (iii) may be carried out with a closed system such as an autoclave or with an open system such as a flask, and the material in the open system is preferably protected by blanketing with a stream of inert gas such as argon.

In one embodiment of the present invention, the process for producing a sulfur-carbon composite material according to the present invention is characterized in that the preparation of the mixture of process step (iii) comprises heating the carbon composite material and the elemental sulfur together at a temperature . ≪ / RTI > The mixture thus prepared is a composite material in which the starting material can no longer be completely separated from each other in a manual manner.

More particularly, the process according to the invention is suitable for industrially manufacturing sulfur-carbon composite materials in continuous and / or batch mode. In the batch mode, this means a batch size of more than 10 kg, more preferably more than 100 kg, even more ideally more than 1000 kg or more than 5000 kg. In continuous mode, this means a production rate of greater than 100 kg / day, more preferably greater than 100 kg / day, even more ideally greater than 10 ton / day or greater than 100 ton / day.

The sulfur-carbon composite material of the present invention obtained in the process according to the present invention is typically further pulverized into a powder form by a subsequent milling step known in the art, which ultimately results in an electrochemical cell, particularly a lithium- Can be used as an essential component of a cathode material for a sulfur battery

The present invention also provides a cathode material for an electrochemical cell, comprising one or more of the sulfur-carbon composite materials of the present invention described above, and optionally one or more binders (C). The cathode material of the present invention preferably includes at least one binder (C) as well as the sulfur-carbon composite material of the present invention.

The at least one binder (C) present in the cathode material of the present invention basically provides mechanical stabilization of the cathode material of the present invention.

In one embodiment of the present invention, the binder (C) is selected from organic (co) polymers. Examples of suitable organic (co) polymers may be halogenated or non-halogenated. Examples are polyethylene oxide (PEO), cellulose, carboxymethylcellulose, polyvinyl alcohol, polyethylene, polypropylene, polytetrafluoroethylene, polyacrylonitrile-methyl methacrylate copolymer, styrene-butadiene copolymer, tetrafluoroethylene Vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), vinylidene fluoride-tetrafluoroethylene copolymer, perfluoroalkyl vinyl ether copolymer, ethylene- Vinylidene fluoride-chlorotrifluoroethylene copolymers, ethylene-chlorotrifluoroethylene copolymers, ethylene-acrylic acid copolymers (optionally at least partially neutralized with an alkali metal salt or ammonia), vinylidene fluoride-chlorotrifluoroethylene copolymers, , An ethylene-methacrylic acid copolymer (optionally at least partially By being neutralized with an alkali metal salt or ammonia), ethylene- (meth) acrylic acid ester copolymer, a polyimide, and polyisobutene.

Suitable binders are, in particular, polyvinylalcohols and halogenated (co) polymers such as polyvinyl chloride or polyvinylidene chloride, especially fluorinated (co) polymers such as polyvinyl fluoride and especially polyvinylidene fluoride and Polytetrafluoroethylene.

The average molecular weight Mw of the kneading agent (C) can be selected from a wide range, and a suitable example is 20,000 to 1,000,000 g / mol.

In one embodiment of the present invention, the cathode material of the present invention is present in the range of 0.1 to 10% by weight, preferably in the range of 1 to 8% by weight, more preferably in the range of 1 to 8% by weight, based on the mass of the sulfur- By weight of the binder.

Binder (C) can be incorporated into the cathode material of the present invention in a variety of ways. For example, it is possible to dissolve a soluble binder (C) such as polyvinyl alcohol in a suitable solvent or solvent mixture (water / isopropanol is a suitable example for polyvinyl alcohol), additional components of the cathode material It is possible to prepare a suspension with After application to a suitable substrate, such as an aluminum foil, the solvent or solvent mixture is removed (e.g., vaporized) to yield an electrode comprised of the cathode material of the present invention. A suitable solvent for polyvinylidene fluoride is NMP.

If it is desired to use a weakly soluble polymer such as polytetrafluoroethylene or tetrafluoroethylene-hexafluoropropylene copolymer as the binder (C), it is preferable that the particles of the binder (C) and the particles of the cathode material A suspension of additional ingredients is produced and hot compressed.

In addition to the sulfur-carbon composite material and the binder (C) of the present invention, the cathode material of the present invention may further include carbon (D), which may be basically the carbon composite (A) . The additional carbon (D) is preferably a polymorphic carbon comprising at least 60% sp ² -hybridized carbon atoms, preferably 75 to 100% sp ² -hybridized carbon atoms. In the present invention, this carbon is also simply referred to as carbon (D), which is known per se. Carbon (D) is an electrically conductive polymorph of carbon. The carbon (D) may be selected from, for example, graphite, carbon black, carbon nanotubes, graphene or a mixture of two or more thereof.

The above percentages are based on all carbon (D) (including any impurities) present in the cathode material with the sulfur-carbon composite material, and refer to wt%.

In one embodiment of the present invention, carbon (D) is carbon black. The carbon black can be selected, for example, from lamp black, furnace black, flame black, thermal black, acetylene black and industrial black. Carbon black may contain impurities, such as hydrocarbons, especially aromatic hydrocarbons, or oxygen-containing compounds or oxygen-containing groups, such as OH groups. In addition, sulfur- or iron-containing impurities may be present in the carbon black.

In one variant, carbon (D) is partially oxidized carbon black.

In one embodiment of the present invention, carbon (D) comprises carbon nanotubes. Carbon nanotubes (simply, CNTs), such as single wall carbon nanotubes (SW CNTs) and preferably multiwall carbon nanotubes (MW CNTs), are known. Their preparation methods and some physical properties are described, for example, in [A. Jess et al. Chemie Ingenieur Technik 2006, 78, 94-100.

In one embodiment of the present invention, the carbon nanotubes have a diameter in the range of 0.4 to 50 nm, preferably 1 to 25 nm.

In one embodiment of the present invention, the carbon nanotubes have a length in the range of 10 nm to 1 mm, preferably 100 to 500 nm.

The carbon nanotubes can be produced by a known method. For example, a mixture of volatile carbon compounds such as methane or carbon monoxide, acetylene or ethylene, or mixtures of volatile carbon compounds, for example syngas, with one or more reducing agents such as hydrogen and / or additional gases, It is possible to decompose in the presence of nitrogen. Another suitable gas mixture is a mixture of carbon monoxide and ethylene. Suitable decomposition temperatures are, for example, in the range of 400 to 1000 占 폚, preferably 500 to 800 占 폚. Suitable pressure conditions for decomposition are, for example, from standard pressure to 100 bar, preferably standard pressure to 10 bar.

Single-walled or multi-walled carbon nanotubes can be obtained, for example, by decomposing a carbon compound in an arc of light in the presence or absence of a decomposition catalyst.

In one embodiment, the decomposition of the volatile carbon compound or the carbon compound is carried out in the presence of a cracking catalyst, for example Fe, Co or preferably Ni.

In the present invention, graphen is understood to mean a nearly ideal or ideally two-dimensional hexagonal carbon crystal having a structure similar to the individual graphite layer.

In one embodiment of the present invention, carbon (D) is selected from graphite, graphene, activated carbon and especially carbon black.

The carbon (D) may be in the form of particles having a diameter in the range of 0.02 to 50 mu m, for example. The average diameter is understood to mean the average diameter of the secondary particles, which is determined as a volume average by a scanning electron microscope.

In one embodiment of the present invention, carbon (D) and especially carbon black have a BET surface area in the range of 20 to 1500 m ² / g, as measured by ISO 9277.

In the present invention, it is also possible to mix two or more, for example two or three, different kinds of carbon (D) with each other instead of one kind of carbon (D). The other kind of carbon (D) may differ, for example, in terms of particle size or BET surface area or contamination level.

 In one embodiment of the present invention, the cathode material of the present invention contains sulfur in an amount of 20 to 80% by weight, preferably 30 to 70% by weight, determined by elemental analysis.

In one embodiment of the present invention, the cathode material of the present invention comprises carbon (D) in the range of 0.1 to 60 wt%, preferably 3 to 30 wt%. This carbon can likewise be measured, for example, by elemental analysis, in which case the evaluation of the elemental analysis is also carried out in such a way that carbon is also incorporated into the inventive cathode material through components (A), (B) and (C) Should be considered.

The sulfur-carbon composite material of the present invention and the cathode material of the present invention are particularly suitable as a cathode or in the manufacture of a cathode, particularly in the manufacture of a cathode of a lithium-containing battery. The present invention provides the use of the sulfur-carbon composite material of the present invention or the cathode material of the present invention as a cathode for an electrochemical cell or for the production of a cathode.

According to the present invention, further characteristics of the sulfur-carbon composite material of the present invention or the cathode material of the present invention are preferably 30 cycles or more, more preferably 50 cycles or more, still more preferably 100 cycles or more, It is possible to manufacture a stable battery cell over 200 cycles or more or 500 cycles or more.

The present invention further provides an electrochemical cell comprising at least one inventive sulfur-carbon composite material or one or more cathodes made from or using the inventive cathode material.

In the present invention, an electrode having a reducing action in a discharge (work) process is referred to as a cathode.

In one embodiment of the present invention, the sulfur-carbon composite material of the present invention or the cathode material of the present invention is processed into a cathode in the form of a continuous belt, for example, processed by a battery manufacturer.

The cathode made from the sulfur-carbon composite material of the present invention or the cathode material of the present invention may have a thickness in the range of, for example, 20 to 500 μm, preferably 40 to 200 μm. These may be, for example, rod-shaped, round, oval or square columnar, or cubic or flat cathode.

In one embodiment of the present invention, the electrochemical cell of the present invention is characterized in that not only the sulfur-carbon composite material of the present invention or the cathode material of the present invention but also metal magnesium, metal aluminum, zinc metal, And at least one electrode comprising metallic lithium.

In a further embodiment of the present invention, the above-described electrochemical cell of the present invention includes a liquid electrolyte containing a lithium-containing conductive salt, as well as the sulfur-carbon composite material of the present invention or the cathode material of the present invention .

In one embodiment of the present invention, the electrochemical cell of the present invention is characterized in that it comprises, in addition to the sulfur-carbon composite material of the present invention or the cathode material of the present invention and one or more electrodes comprising further electrodes, At least one non-aqueous solvent selected from among polymers, cyclic or acyclic ethers, cyclic or acyclic acetals, cyclic or acyclic organic carbonates, and ionic liquids, which may be liquid or solid at room temperature and is preferably liquid at room temperature .

Examples of suitable polymers are, in particular, polyalkylene glycols, preferably poly-C ₁ -C ₄ -alkylene glycols, in particular polyethylene glycols. Polyethylene glycols can account for up to 20 mole% of one or more poly-C ₁ -C ₄ -alkylene glycols in copolymerized form. The polyalkylene glycols are preferably double-methyl- or ethyl-capped polyalkylene glycols.

The molecular weight Mw of suitable polyalkylene glycols, and particularly suitable polyethylene glycols, may be at least 400 g / mol.

Suitable polyalkylene glycols, and particularly suitable polyethylene glycols, may have a molecular weight Mw of 5,000,000 g / mol or less, preferably 2,000,000 g / mol or less.

Examples of suitable non-cyclic ethers are diisopropyl ether, di-n-butyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dimethoxyethane .

Examples of suitable cyclic ethers are tetrahydrofuran and 1,4-dioxane.

Examples of suitable non-cyclic acetals are, for example, dimethoxymethane, diethoxymethane, 1,1-dimethoxyethane, and 1,1-diethoxyethane.

An example of a suitable cyclic acetal is 1,3-dioxane, especially 1,3-dioxolane.

Examples of suitable non-cyclic organic carbonates are dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate.

Examples of suitable cyclic organic carbonates are compounds of the formulas (X) and (XI)

In this formula,

R ¹ , R ² and R ³ are the same or different and are each hydrogen and C ₁ -C ₄ alkyl (eg methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec- Butyl), < / RTI >

R ² and R ³ are preferably not both tertiary butyl.

In a particularly preferred embodiment, R ¹ is methyl and R ² and R ³ are each hydrogen, or R ¹ , R ² and R ³ are each hydrogen.

Another preferred cyclic organic carbonate is vinylene carbonate of formula (XII)

.

.

It is preferred to use the solvent (s) in a range of 1 ppm to 0.1% by weight when determined by the so-called anhydrous condition, i.e., the water content by Karl Fischer titration.

In one embodiment of the present invention, the electrochemical cell of the present invention comprises at least one conductive salt, preferably a lithium salt. Suitable examples of lithium salt are _{LiPF 6, LiBF 4, LiClO 4} , LiAsF 6, LiCF 3 SO 3, LiC (C n F 2n +1 SO 2) 3, for example lithium imide _{LiN (C n F 2n + 1} SO 2) ₂ (where n is a number ranging from 1 to 20 _{Im), LiN (SO 2 F)} 2, Li 2 SiF 6, LiSbF 6, LiAlCl 4, and a formula (C _n F _{2n +1} SO _{2) m} salt of XLi (wherein, m Is defined as m = 1 when x is selected from oxygen and sulfur, m = 2 when x is selected from nitrogen and phosphorus, and m = 3 when x is selected from carbon and silicon).

Preferred conducting salts are _{LiC (CF 3 SO 2) 3} , LiN (CF 3 SO 2) 2, LiPF 6, LiBF 4, LiClO 4 is selected from, and even more preferably LiPF ₆ and LiN (CF ₃ SO _{2) 2} .

In one embodiment of the invention, the electrochemical cell of the present invention comprises at least one separator for mechanically separating the electrodes from one another. Suitable separator plates are polymer films, especially porous polymer films, which are non-reactive with respect to metal lithium and to lithium sulfide and rhodium polysulfide. Particularly suitable materials for separator plates are polyolefins, in particular porous polyethylene films and porous polypropylene films.

Particularly polyolefin separators made of polyethylene or polypropylene can have a porosity ranging from 35 to 45%. Suitable pore sizes are, for example, in the range of 30 to 500 nm.

In another embodiment of the present invention, the selected separating plate may be a separating plate composed of a PET nonwoven fabric filled with inorganic particles. Such a separator may have a porosity ranging from 40 to 55%. Suitable pore sizes are, for example, in the range of 80 to 750 nm.

The electrochemical cell of the present invention can be assembled with a lithium ion battery.

Accordingly, the present invention further provides the use of the above-described electrochemical cell of the present invention in a lithium ion battery.

The present invention further provides a lithium ion battery including at least one electrochemical cell of the present invention described above. The electrochemical cells of the present invention can be combined with each other in a lithium ion battery of the present invention, for example, in series connection or in parallel connection. A series connection is preferred.

The electrochemical cell of the present invention is particularly notable for high capacity, high performance even after repeated charging, and very delayed battery death. The electrochemical cell of the present invention is particularly suitable for use in an automobile, an electric motor-operated bicycle, such as a pedelec, an airplane, a vessel, or an energy storage. Such uses form a further part of the subject matter of the present invention.

The present invention also provides use of the electrochemical cell of the present invention described above in an automobile, an electric motor-operated bicycle, an airplane, a ship or an energy storage.

The use of the lithium ion battery of the present invention in an apparatus provides the advantage of less performance loss during long operation time before recharging and long operation time. If an attempt is made to achieve an equivalent operating time with an electrochemical cell with a lower energy density, the greater weight of the electrochemical cell will have to be accommodated.

Accordingly, the present invention further provides a device of the lithium ion battery of the present invention, particularly for use in a mobile device. An example of a mobile device is a vehicle, such as a car, a bicycle, an airplane, or a watercraft, such as a boat or a ship. Other examples of portable devices are portable ones, such as computers, especially laptops, telephones or power equipment (e.g. from the construction sector), especially drills, battery-powered screw drivers or battery- )to be.

The present invention also relates to

(aa) particles of at least one electrically conductive additive having an aspect ratio of 10 or greater

(A) at least one carbonized product of the carbonaceous starting material

For the production of electrochemical cells, more preferably for the production of electrodes for electrochemical cells, more preferably for the production of cathodes for electrochemical cells, especially for the production of cathodes for lithium-sulfur batteries, Lt; / RTI > for use in the manufacture of a spray gun.

Carbon composite material, the carbonaceous starting material, the carbonized product (a), and the particle (aa) correspond to the above description of these components for the sulfur-carbon composite material of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the schematic structure of a degraded form electrochemical cell for testing of the composite material of the present invention and the non-inventive composite material.
In Figure 1, the reference numerals have the following meanings:
1,1 'volts
2,2 'nut
3,3 'sealing ring - two in each case, in each case somewhat less sealing ring, the second is not shown here
4 spiral spring
5 Nickel output conductor
6 Housing

The present invention is illustrated by the following examples, which do not limit the present invention.

% Values relate to% by weight unless otherwise stated.

I. Synthesis of carbonization products of at least one elastomeric starting material

I.1 Synthesis of carbon composite material C.1 of the present invention

30.7 g of Konstanti (Aldrich) and 0.76 g of MF-C110 carbon fiber (Carbon-NT & F 21, A-7000 Eisenstart) were intimately mixed by means of a mortar and pelletized in a nitrogen- Lt; / RTI > for 2 hours. The coarse particles of the obtained product were then milled and pulverized in a ball mill (Fritsch Pulverisette) at 300 rpm for 10 minutes to obtain a fine powder (yield: 6.9 g).

I.2 Synthesis of non-inventive carbonized product V-C.2

30.8 g of Constach (Aldrich) was pyrolyzed in a nitrogen-purged crucible at 600 占 폚 for 2 hours. The hard, glossy black coarse particles of the product were then removed, weighed and ground. 6.05 g of a fine powder remained. This was pulverized in a ball mill (Fritsch Pulverisette) at 300 rpm for 10 minutes and MF-C110 carbon fiber (Carbon-NT & F 21, A-7000 Eisenstart material) And homogenized with 0.75 g.

II. Synthesis of sulfur-carbon materials

II.1 Synthesis of the sulfur-carbon composite material SC.1 of the present invention

1 g of the previously prepared material C.1 and 6 g of sulfur (Aldrich) were intimately mixed in a mortar and then heat-treated at 180 ° C for 6 hours in a nitrogen-purged sealed steel autoclave. After cooling, the resulting sulfur-carbon composite material SC.1 was ground in a ball mill (Fritsch Pulverisette) at 300 rpm for 10 minutes. Finally, the sulfur content of the gray substance SC.1 was determined by means of elemental analysis, and a value of 84.2% was confirmed.

II.2 Synthesis of sulfur-carbon composite material V-SC.2 not the present invention

1 g of the previously prepared material VC.2 and 6 g of sulfur (Aldrich) were intimately mixed in a mortar and then heat-treated at 180 ° C. for 6 hours in a nitrogen-purged sealed steel autoclave. After cooling, the resulting grayish yellow-carbon composite material V-SC.2 was ground in a ball mill (Fritsch Pulverisette) at 300 rpm for 10 minutes. Finally, the sulfur content of V-SC.2 was determined by means of elemental analysis and a value of 83% was confirmed.

III. Manufacture of cathode

III.1 Manufacture of the inventive cathode K.1 from SC.1

To prepare a slurry of the cathode material, 0.295 g of carbon black (commercially available from Super P, Timcal AG (Bordeaux, Switzerland 6743) and 0.050 g of polyvinyl alcohol (Celvol 425 , Commercially available from Celanese Corporation, USA) was added to a suspension of 0.655 g of SC.1 in approximately 10 ml of water / isopropanol (1: 1). For dispersion, the mixture was transferred to a stainless steel mill and a ball mill (pearl barley set from preheater) was used with stirring balls at 300 rpm for 30 minutes with a stainless steel ball. After dispersion, a very homogeneous A slurry was formed (by adding a small amount of water / isopropanol, the desired concentration was established in each case). The slurry was applied to an aluminum foil using a manual coating bar (gap width 140 占 퐉). The wet electrode tape was then dried overnight in a drying oven at 40 DEG C under reduced pressure. Solid loading of 2.53 mg / cm < ² > was achieved. From the starting weight, a theoretical sulfur content of 55% in the cathode was calculated.

III.2 Manufacture of non-inventive cathode V-K.2 from V-SC.2

To prepare a slurry of the cathode material, 0.294 g of carbon black (commercially available from Super P, Timcal AG (Bordeaux, Switzerland 6743) and 0.051 g of polyvinyl alcohol (Celvol 425 , Commercially available from Celanese Corporation, USA) was added to a suspension of 0.655 g of V-SC.2 in approximately 10 ml of water / isopropanol (1: 1). For dispersion, the mixture was transferred to a stainless steel mill and a ball mill (pearl barley set from preheater) was used with stirring balls at 300 rpm for 30 minutes with a stainless steel ball. After dispersion, a very homogeneous A slurry was formed (by adding a small amount of water / isopropanol, the desired concentration was established in each case). The slurry was applied to an aluminum foil using a manual coating bar (gap width 140 占 퐉). The wet electrode tape was then dried overnight in a drying oven at 40 DEG C under reduced pressure. Solid loading of 2.51 mg / cm < ² > was achieved. From the starting weight, a theoretical sulfur content of 55% in the cathode was calculated.

IV. Testing cathodes in electrochemical cells

For the electrochemical characterization of the cathode K.1 of the present invention and the comparative cathode V-K.2, an electrochemical cell was fabricated according to FIG. For this purpose, the following components were used in each case, as well as the cathodes prepared in III:

Anode: Li foil, thickness 50 탆

Separate plate: Microporous triple layer (PP / PE / PP) (commercially available as Celgard (trade name) 2340)

Cathode: According to Example III

Electrolyte: 1 dioxolan and dimethoxyethane: 1 mixture of 1 _{M LiTFSI (LiN (SO 2 CF} 3) 2)

Charging and discharging of each electrochemical cell was performed at a relative current of 0.45 mA / cm ² (charge) and 0.70 mA / cm ² (discharge) (based on cathode area) between 1.8 V and 2.5 V voltage limits, Respectively. The test results of the two electrochemical cells are summarized in Table 1 below.

[Table 1] Test results of the present invention and non-inventive electrochemical cell

Claims (20)

(A) at least one carbon composite material and (B) a sulfur-carbon composite material containing elemental sulfur,
The carbon composite material
(aa) particles of at least one electrically conductive additive having an aspect ratio of 10 or greater
(A) at least one carbonized product of the carbonaceous starting material
Carbon composite material. The method according to claim 1,
Wherein the elastomeric starting material is selected from carbohydrates, resins, coke, pitch, polyacrylonitrile, styrene-acrylonitrile copolymers, melamine-formaldehyde resins and phenol-formaldehyde resins. 3. The method according to claim 1 or 2,
Wherein the particles of the electrically conductive additive have an average diameter in the range of 50 nm to 100 mu m. 4. The method according to any one of claims 1 to 3,
Wherein the particles of the electrically conductive additive have an electrical conductivity in the range of from 0.1 mS / cm to 30,000 S / cm. 5. The method according to any one of claims 1 to 4,
Wherein the particles of the electrically conductive additive are selected from the group consisting of carbon fibers; A fiber of a transparent metal oxide selected from indium tin oxide, Al-doped zinc oxide, Ga-doped zinc oxide, In-doped zinc oxide, F-doped tin dioxide, and Sb-doped tin dioxide; Fibers of metal carbides selected from WC, MoC and TiC; And metal fibers selected from aluminum and steel. 6. The method according to any one of claims 1 to 5,
Wherein the weight ratio of the particles of the electrically conductive additive based on the total weight of the carbon composite material (A) is in the range of 0.1 to 60 wt%. 7. The method according to any one of claims 1 to 6,
Carbon composite material and sulfur in a weight ratio of 10 to 95% by weight based on the sum of the weight ratios. 8. The method according to any one of claims 1 to 7,
A sulfur-carbon composite material in which the sulfur-carbon composite material is in a particulate form. (A) at least one carbon composite material, and (B) elemental sulfur, wherein the carbon composite material comprises
(aa) particles of at least one electrically conductive additive having an aspect ratio of 10 or greater
(A) at least one carbonized product of the carbonaceous starting material
The method for producing a sulfur-carbon composite material according to any one of claims 1 to 8,
(i) preparing a mixture comprising at least one elastomeric starting material, and particles of at least one electrically conductive additive having an aspect ratio of at least 10,
(ii) carbonizing said elastomeric starting material to form a carbonized product comprising particles of an electrically conductive additive to provide a carbon composite material; and
(iii) preparing a mixture of elemental sulfur and the carbon composite material obtained in step (ii)
≪ / RTI > 10. The method of claim 9,
Wherein in step (ii) the carbonization is carried out at < RTI ID = 0.0 > 500 C < / RTI > 11. The method according to claim 9 or 10,
Wherein the preparation of the mixture in step (iii) comprises heating the carbon composite material and the elemental sulfur together to a temperature in the range of from 100 to 200 占 폚. A cathode material for an electrochemical cell, comprising at least one sulfur-carbon composite material according to any one of claims 1 to 8, and optionally at least one binder (C). An electrochemical cell comprising at least one cathode made from or made from a sulfur-carbon composite material according to any one of claims 1 to 8 or a cathode material according to claim 12. 14. The method of claim 13,
An electrochemical cell further comprising at least one electrode comprising metal lithium. The method according to claim 13 or 14,
An electrochemical cell comprising a liquid electrolyte comprising a lithium-containing conductive salt. 16. The method according to any one of claims 13 to 15,
An electrochemical cell comprising at least one non-aqueous solvent selected from polymers, cyclic or acyclic ethers, cyclic or acyclic acetals, and cyclic or acyclic organic carbonates. Use of an electrochemical cell according to any one of claims 13 to 16 in a lithium ion battery. A lithium ion battery comprising at least one electrochemical cell according to any one of claims 13 to 16. Use of an electrochemical cell according to any one of claims 13 to 16 in an automobile, an electric motor-driven bicycle, an airplane, a vessel or an energy storage. (aa) particles of at least one electrically conductive additive having an aspect ratio of 10 or greater
(A) at least one carbonized product of the carbonaceous starting material
Wherein the carbon composite material is a carbon composite material.

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