Pre-lithiated silicon-carbon composite material, anode containing the same, and method for producing the composite material

Abstract

The present invention relates to a lithium-silicon-carbon composite material, particularly formed as a surface-coated lithium-silicon-carbon composite material, having micropores and mesopores and a total pore volume of 0.5 cm 3 / g or more, a silicon content of 30% to 70% (including 30% and 70%), a Li content of 2% to 20% (including 2% and 20%), and a first surface coating layer that is at least partially coated and forms a surface coating film on the surface region of the lithium-silicon-carbon composite material containing one or more elements from Li, B, Al, Si, P, Ti, Zr, Nb, and / or W.

Description

Technical Field

[0001] The present disclosure relates to a surface-coated lithium-silicon-carbon composite material containing a porous carbon scaffold containing micropores and mesopores having pore volume. Further, the present disclosure relates to a method for manufacturing a surface-coated lithium-silicon-carbon composite material, an anode electrode, and an electrochemical energy storage device.

Background Art

[0002] Lithium-ion batteries are widely used and provide stored energy to multiple components. In particular, in electric vehicles and hybrid electric vehicles, such lithium-ion batteries supply electrical energy to vehicle components and drive trains. In such use cases, a long electric driving range is highly desirable, which can be achieved by increasing the capacity of the battery. The capacity of the battery can be increased by increasing the surface area of the electrodes. This is achieved by a more complex surface structure. Various methods are known for coating at least one of the current collectors of the anode with silicon-carbon in order to increase the area for reversible lithium intercalation and the amount of lithium ions involved during the charge and discharge procedures. Such complex surface structures and coating films can be prone to chemical reactions with environmental compounds, for example, during the manufacture of lithium-ion cells. In particular, during the electrolyte filling of a lithium-ion cell, the anode and a part of its surface structure can be accidentally exposed to harmful, for example, oxidizing, substances.

[0003] Furthermore, over a number of cycles, lithium-ion batteries are still prone to the effect of capacity loss due to the formation of a solid electrolyte interphase layer (SEI layer). Such an SEI layer is usually formed by the reduction of organic solvents and anions on the electrode surface during the charge and discharge cycles of a lithium-ion battery. The relevant part of the SEI layer formation occurs during the first charge and discharge cycle.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2017 / 0015559 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] An object of the present disclosure is to provide a method for manufacturing a lithium-silicon-carbon composite material having improved chemical stability and reducing lithium loss for the formation of the SEI layer in the first cycle of an electrochemical device. This object is achieved by the subject matter of the independent claims. Further developments of the subject matter of the independent claims are provided in the dependent claims. [Means for Solving the Problems]

[0006] According to one aspect of the present disclosure, a lithium-silicon-carbon composite material is provided. The lithium-silicon-carbon composite material can be formed as a surface-coated lithium-silicon-carbon composite material or as a surface-coated lithium-alloy-silicon-carbon composite material. [Modes for Carrying Out the Invention]

[0007] Such a lithium-silicon-carbon composite material can be used in an anode electrode and thus in an electrochemical energy storage device such as a lithium-ion cell or battery.

[0008] The lithium-silicon-carbon composite material has a porous carbon scaffold having micropores and mesopores and a total pore volume of more than 0.5 cm 3 / g.

[0009] Furthermore, the porous carbon scaffold of the lithium-silicon-carbon composite material can contain a plurality of particles to further adjust its chemical and mechanical properties. By providing additional particles inside the porous carbon scaffold of the lithium-silicon-carbon composite material, it becomes possible to control the kinetics of lithium ions inside the lithium-silicon-carbon composite material.

[0010] The lithium-silicon-carbon composite material has a silicon content of 30% to 70% including 30% and 70%. Furthermore, a Li content of 2% to 20% including 2% and 20% is incorporated into the lithium-silicon-carbon composite material. Accordingly, the lithium-silicon-carbon composite material is provided in a prelithiated form. The silicon content and the lithium content can be defined in relation to the weight / mass or volume of the entire lithium-silicon-carbon composite material.

[0011] Furthermore, the lithium-silicon-carbon composite material contains a first surface coating layer that is at least partially coated and forms a surface coating film on the surface region of the lithium-silicon-carbon composite material. The at least partially coated first surface coating layer contains one or more elements from Li, B, Al, Si, P, Ti, Zr, Nb, and / or W.

[0012] In a further aspect of the present invention, a cathode electrode containing a surface-coated silicon-carbon material is provided. Preferably, the cathode electrode can contain a current collector, such as a metal foil. The lithium-silicon-carbon composite material can be disposed on one or both sides of the current collector to improve the electrical properties of the cathode electrode. The surface-coated silicon-carbon material is preferably in a prelithiated form and is thus a surface-coated lithium-silicon-carbon material.

[0013] The lithium-silicon-carbon composite material can contain at least one surface coating film, for example, on a surface region that is not in contact with the current collector of the cathode electrode.

[0014] By providing at least one surface coating, such as a first surface coating layer, the chemical and mechanical stability of a surface-coated lithium-silicon-carbon composite material, and thus an anode electrode having such a material, is improved. In particular, the surface coating can be applied by chemical vapor deposition such as an atomic layer deposition process. Such a surface coating can also be applied onto a lithium-silicon-carbon composite material having a complex or non-uniform surface shape.

[0015] Due to the lithium introduced into the surface-coated lithium-silicon-carbon composite material, the formation of the SEI layer during the first charge-discharge cycle in an anode electrode having such a material is prevented or minimized. The SEI layer is typically formed by the reduction of an organic solvent and anions on the surface of the anode electrode during the charge-discharge cycle of an electrochemical cell. Since such organic solvents and anions do not exist in the prelithiated composite material, the formation of the SEI layer is minimized.

[0016] Lithium ions for reversible lithium intercalation can bypass the first surface coating without a significant reduction in the corresponding kinetics when the at least partially applied first surface coating is formed as a layer having a thickness of 0.1 nm to 1 μm.

[0017] According to a further embodiment, the first surface coating contains a metal oxide from at least one or more of the elements B, Al, Si, Zr, Nb, and / or W. For example, suitable metal oxides are Al 2 O 3 and / or LiAlO 2 which can be formed as.

[0018] In another embodiment, suitable metal oxides are ZrO 2 or / and Li 2 ZrO 3 , or, Al 2 O 3 , ZrO 2 and can be formed as a mixture of mixed lithium aluminum oxide and lithium zirconium oxide.

[0019] In another embodiment, the first surface coating layer contains a metal oxide from Li in addition to Al 2 O 3 In addition to Li, it contains a metal oxide from Li.

[0020] A suitable surface coating can be applied by atomic layer deposition (ALD) of trimethylaluminum with water or oxygen (subsequent ALD cycles more than twice) at a temperature between 100 °C and 450 °C, and if desired, subsequently, the obtained aluminum oxide and aluminum hydroxide are reacted with a lithium compound such as Li-N(SiMe 3 ) 2 to form a lithiated metal oxide. Such a coating can also be applied in combination with heat exposure and / or in combination with a catalyst. In another embodiment, the surface coating layer can be applied by mixing a metal oxide compound (Al 2 O 3 , Zr(OH) 4 , ZrO(OH) 2 ) with a lithium compound and then performing a heat treatment step at a temperature above 200 °C.

[0021] In a further embodiment, the first surface coating covers at least 50% of the surface area of the lithium-silicon-carbon composite material. Therefore, most of the surface area of the lithium-silicon-carbon composite material can be protected by the first surface coating. The surface area of the lithium-silicon-carbon composite material is defined as the total surface area in its final form applied to the anode electrode. Therefore, all or most of the surface of the lithium-silicon-carbon composite material that is not in contact with the current collector foil of the anode electrode can contain a surface coating.

[0022] The surface coating of the lithium-silicon-carbon composite material can contain a plurality of surface coating layers that can also at least partially cover the available surface area of the lithium-silicon-carbon composite material. Different surface coating layers can at least partially overlap each other.

[0023] A lithium-silicon-carbon composite material can have additional protection when the surface region of the lithium-silicon-carbon composite material is at least partially covered by a first surface coating layer and at least partially covered by a second surface coating layer. Preferably, the second surface coating layer is at least partially applied over and / or in addition to the first surface coating layer. The second surface coating layer allows for further control of the chemical and mechanical stability of the lithium-silicon-carbon composite material.

[0024] According to one embodiment of the lithium-silicon-carbon composite material, the second surface coating layer is formed as a carbon coating. Such a second surface coating layer can result in a reduction in the electrical resistance of the lithium-silicon-carbon composite material in the transition region between the second surface coating layer and the current collector or metal when using the lithium-silicon-carbon composite material in an electrode. Further, such a second surface coating layer can improve the conductivity within the layer of the lithium-silicon-carbon composite material. In another embodiment, an additional process is applied to further passivate the surface region or the lithium-silicon-carbon composite material by flushing in a dry atmosphere (O 2 , N 2 or a mixture thereof) at an elevated temperature of 120 °C to 250 °C. This method helps to improve the processability with an aqueous binder solution and especially helps to avoid the generation of H 2 .

[0025] In a further embodiment of the lithium-silicon-carbon composite material, the lithium-silicon-carbon composite material contains a surface area in the range of 2 m 2 / g to 30 m 2 / g, more preferably in the range of 4 m 2 / g to 10 m 2 / g. 2 m 2 / g, 30 m 2 / g, 4 m 2 / g, and 10 m 2The appropriate limits of / g may also form part of the defined range. Thus, the first surface coating layer and / or the second surface coating layer can be efficiently applied onto the lithium-silicon-carbon composite material with an increased surface area due to its porous carbon scaffold.

[0026] According to a further embodiment of the lithium-silicon-carbon composite material, the lithium-silicon-carbon composite material contains lithium. Further, the first surface coating layer may contain lithium formed as a metal oxide. For example, the first surface coating may be a mixture of Al 2 O 3 , AlO(OH) and LiAlO 2 , or may include a further lithium oxide that can act as a channel for lithium ions during reversible lithium intercalation between the electrolyte and the lithium-silicon-carbon composite material. Thus, the kinetics of lithium ions passing through the first and / or second surface coatings can be improved.

[0027] According to a further aspect of the present invention, a method for manufacturing a surface-coated lithium-silicon-carbon composite material is provided. In the steps of the method, a porous carbon scaffold having micropores and mesopores is provided. In a further step, a Li compound is introduced into the micropores and mesopores of the provided porous carbon scaffold by a solution-based infiltration method. Then, the solvent of the solution-based infiltration method is removed to obtain or form a carbon scaffold having micropores and mesopores into which the Li compound has been introduced. Further, at least one additional compound containing at least one of Si and optionally Fe, Al, Ni, W, and / or Ti is introduced into the micropores and mesopores of the porous carbon scaffold by chemical vapor infiltration to form a lithium-alloy-carbon-silicon composite material. The additional compound is preferably SiH 4 . At least one surface coating layer is at least partially applied onto the surface region of the lithium-alloy-carbon composite material. The at least one surface coating layer contains silicon oxide, aluminum oxide, zirconium oxide, or lithium oxide. Thus, after applying the at least one surface coating layer, a surface-coated lithium-silicon-carbon composite material is formed.

[0028] Aluminum or zirconium may remain in the material so that the surface-coated lithium-silicon-carbon composite material can also be formed as a surface-coated lithium-alloy-carbon-silicon composite material.

[0029] By providing a surface coating film containing silicon oxide, aluminum oxide, or zirconium oxide, the lithium-silicon-carbon composite material can be protected from unintended chemical reactions such as uncontrolled oxidation processes. In particular, during the manufacture of battery cells or electrochemical energy storage devices, electrodes containing the surface-coated lithium-silicon-carbon composite material provide improved chemical stability and reduce the likelihood of unwanted chemical reactions by at least a partial surface coating film.

[0030] To introduce lithium into the lithium-silicon-carbon composite material, the lithium compound can be introduced as LiAlH into the micropores and mesopores of the provided porous carbon scaffold by a solution-based infiltration method. 4 The solution can be removed using vacuum and / or heating at a temperature above, for example, 100 °C. After heating the resulting material and introducing SiH at a temperature of, for example, 450 °C, CH 4 which is a by-product of chemical vapor infiltration, and H 4 and H 2 may also evaporate. Therefore, only the Li-Al of LiAlH 4 remains and a Li-Al-Si alloy can be formed within the porous carbon scaffold.

[0031] In one embodiment, at least one surface coating layer of the surface region coating film of the lithium-silicon-carbon composite material is applied by a vapor deposition method. Therefore, methods such as atomic layer deposition or molecular layer deposition can be implemented to provide a surface coating film having a controlled and uniform layer thickness.

[0032] In a further embodiment, at least one surface coating of a lithium-alloy-carbon-silicon composite material or a lithium-silicon-carbon composite material is treated with a metal alkoxide or a metal amide or an alkyl metal compound to form a treated compound surface on the surface region of the lithium-silicon-carbon composite material, and this treated compound surface is treated with moisture or oxygen or ozone to form at least one layer of a first surface coating layer. Such materials for forming the treated compound surface are widely used and can thus be provided in a cost-effective manner. For example, trimethylaluminum can be utilized to form the treated compound surface. By further heat treatment of the surface-coated lithium-silicon-carbon compound, lithium from the lithium-silicon-carbon composite material reacts with aluminum oxide and / or zirconium oxide to form lithiated Al-O and Zr-O compounds such as LiAlO 2 and / or Li 2 ZrO 3 as surface coating layers.

[0033] In another embodiment, at least one surface coating layer of the surface region of the lithium-silicon-carbon composite material is alternatively formed containing lithium. Thus, for example, in addition to Al 2 O 3 , lithium can be provided as LiAlO 2 to introduce molecular channels for faster lithium ion exchange between the electrolyte and the lithium-silicon-carbon composite material of the electrode.

[0034] According to a further embodiment, the surface coating of the surface region of the lithium-silicon-carbon composite material contains a metal oxide from at least one of the element groups B, Al, Si, Zr, Nb, W and / or Li. Thus, in the case of atomic layer deposition or molecular layer deposition, the metal oxide is utilized as a precursor. Alternative or additional precursors are ZrO 2 , TiO 2 , Al 2 O 3 , SiN x , TaN xIt can be formed as such and introduced by a mixing method. Further, Nb(OEt) 5 or Li-N(SiMe 3 ) 2 and the like can be introduced to accurately control the chemical composition of the at least one surface coating film. Therefore, the method for manufacturing a surface-coated lithium-silicon-carbon composite material includes a plurality of materials capable of adjusting the chemical and mechanical properties of the surface coating film.

[0035] In a further embodiment, during the formation of at least one surface coating layer of the surface coating film of the lithium-silicon-carbon composite material, a temperature in the range of 25°C to 550°C is applied. Therefore, methods such as thermal atomic layer or molecular layer deposition or plasma-enhanced atomic layer or molecular layer deposition are suitable for the manufacture of the surface-coated lithium-silicon-carbon composite material.

[0036] According to a further embodiment, the lithium-silicon-carbon composite material is treated with a metal alkoxide or a metal amide or an alkyl metal compound to form a treated compound surface, and the treatment of the treated compound surface with water or oxygen or ozone is repeated at least once. Therefore, it is possible to ensure the formation of a flat coating film in the surface region of the lithium-silicon-carbon composite material without leaving any undesirable traces of the treated compound, for example, AlCH 3 .

[0037] When a temperature in the range of 25°C to 550°C is applied during the treatment of the treated compound with water or oxygen or ozone, the manufacturing method can be accelerated. Preferably, the manufacturing temperature of this step is in the range of 250°C to 450°C, more preferably in the range of 350°C to 400°C.

[0038] According to a further aspect of the present invention, a method for manufacturing at least one anode electrode is provided. In the process, a silicon-carbon composite material mixture having at least one carbon is mixed. Preferably, the silicon-carbon composite material mixture is formed as a lithium-silicon-carbon composite material mixture.

[0039] In a further step, the silicon-carbon composite material mixture is combined with at least one aqueous binder solution and / or at least one non-aqueous binder solution to form an electrode paste. Further, the electrode paste is at least partially applied onto at least one surface of a current collector. The current collector may be formed as a foil made of a conductive material.

[0040] In a further step, the current collector coated with the electrode paste is dried at a temperature of 100°C to 140°C to form at least one anode electrode.

[0041] As the binder, a styrene-butadiene rubber / carboxymethyl cellulose (CMC / SBR) blend, polyacrylic acid (PAA) and / or lithium polyacrylate (LiPAA) or sodium polyacrylate (NaPAA) can be utilized. In an alternative embodiment, the binder is formed as a fluoropolymer such as polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer resin (PFA), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), polyvinyl fluoride (PVF), ethylene chlorotrifluoroethylene (ECTFE), polyvinylidene fluoride (PCDF), polychlorotrifluoroethylene (PCTFE), trifluoroethanol, or a combination of at least one of these materials and at least one other material. In a further embodiment, the binder is a polyimide or a copolymer of polyacrylic acid and styrene-butadiene. A further possible binder may be formed as methyl methacrylate or polyvinylidene difluoride.

[0042] The step of surface coating can be applied after the drying process of the electrode paste, or the silicon-carbon composite material can be provided in a pre-surface-coated form.

[0043] According to a further aspect of the invention, depending on the preferred application, the manufacturing process of the anode electrode can also be carried out based on a dried or semi-dried silicon-carbon composite material mixture.

[0044] In a first step, a dry silicon-carbon composite material mixture containing graphite particles and / or carbon black particles combined with a binder powder is provided. The binder powder can be formed as PTFE powder.

[0045] Optionally, 5% - 10% ethylene carbonate can be added to the mixture.

[0046] Next, the silicon-carbon composite material mixture combined with the binder powder is at least partially applied by calendaring on at least one surface of a conductor foil or current collector. In a further step, at least one surface coating is applied to the surface region of the lithium-silicon-carbon composite material forming a surface-coated lithium-silicon-carbon composite material, and the at least one surface coating contains aluminum oxide or zirconium oxide and at least partially covers the surface region of the lithium-silicon-carbon composite material.

[0047] Next, the conductor foil having the applied dry or semi-dry electrode paste is dried at a temperature of, for example, 100°C to 140°C to form at least one anode electrode.

[0048] In a further aspect of the present invention, an electrochemical energy storage device, particularly formed as a lithium-ion battery or a lithium-ion battery cell, is provided. The electrochemical energy storage device contains at least one anode electrode of the present invention, at least one cathode electrode, a separator disposed between the cathode electrode and the anode electrode, and an electrolyte containing lithium ions. The cathode electrode preferably contains a transition metal oxide. Preferably, the components of the electrochemical energy storage device are disposed inside a housing or case, such as an aluminum pouch.

[0049] By using an anode electrode having a surface-coated silicon-carbon material, the requirements for a drying chamber environment for manufacturing an electrochemical energy storage device can be reduced thanks to the surface-protected anode electrode.

[0050] In a further aspect, the use of a lithium-silicon-carbon composite material in the anode electrode is disclosed, where the silicon-carbon composite material contains a porous carbon scaffold containing micropores and mesopores, a total pore volume of 0.5 cm3 / g or more, a silicon content of 30% to 70%, a Li content of 2% to 20% including 2% and 20%, and at least a partially applied first surface coating layer that forms a surface coating film on the surface region of the lithium-silicon-carbon composite material containing one or more elements from Li, B, Al, Si, P, Ti, Zr, Nb, and / or W. The silicon content and the lithium content can be defined in relation to the weight / mass or volume of the entire lithium-silicon-carbon composite material.

[0051] In a further embodiment, the surface coating film layer on the silicon-carbon composite material has a thickness in the range of 0.1 nm to 0.1 μm.

[0052] In a further embodiment, the surface coating film layer on the lithium-silicon-carbon composite material contains a metal oxide from at least one or more of the element groups B, Al, Si, Zr, Nb, W, and / or Li.

[0053] In a further embodiment, the surface coating film region of at least one surface coating film covers 50% or more of the surface region of the lithium-silicon-carbon composite material.

[0054] In a further embodiment, the lithium-silicon-carbon composite material contains a further or second surface coating film layer on top of the first surface coating film layer, whereby the first surface coating film layer and the second surface coating film at least partially form a surface coating film region.

[0055] In a further embodiment, the further surface coating film or the second surface coating film is a carbon coating film.

[0056] In a further aspect, the use of an anode electrode in the electrochemical energy storage device of the present invention is provided.

[0057] Based on the schematic embodiments shown in the accompanying drawings, the present disclosure will be described in more detail below.

Brief Description of the Drawings

[0058]

Figure 1

Figure 2

Figure 3

[0059] In the drawings, the same reference numerals identify like elements. The sizes and relative positions of the elements in the figures are not necessarily drawn to scale, and some of these elements are enlarged and arranged to improve the clarity of the figures. Further, the particular shapes of the elements depicted are not intended to convey any information regarding the actual shapes of the particular elements, and are selected only to facilitate recognition in the drawings.

[0060] Unless the context requires otherwise, throughout this specification and the claims, the term "comprise" and its variations such as "comprises" and "comprising" are to be understood in an open inclusive sense, i.e., "including but not limited to". As used herein, any concentration range, percentage range, ratio range, or integer range is to be understood to include any integer value within the specified range and, where appropriate, fractions thereof (such as one-tenth and one-hundredth of an integer), unless otherwise indicated. As used herein, the terms "about" and "approximately" mean ±20%, ±10%, ±5%, or ±1% of the indicated range, value, or structure, unless otherwise indicated. The terms "a" and "an" as used herein are to be understood to refer to "one or more" of the recited components. The use of an alternative (e.g., "or") is to be understood to mean either one of the alternatives, both, or any combination thereof.

[0061] Throughout this specification, references to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural references unless the context clearly dictates otherwise.

[0063] The term "carbon portion" of a silicon-carbon composite material refers to a material or substance composed of carbon or containing at least carbon. In this regard, the carbon material can contain high-purity, amorphous, and crystalline materials. The carbon material can be activated carbon, pyrolyzed dry polymer gel, pyrolyzed polymer cryogel, pyrolyzed polymer xerogel, pyrolyzed polymer aerogel, activated dry polymer gel, activated polymer cryogel, activated polymer xerogel, activated polymer aerogel, or a combination thereof. In a further embodiment, carbon can be produced by pyrolysis of coconut shells or other organic waste. In this regard, a polymer is a molecule containing two or more repeating structural units. Porous carbon, also known as a porous carbon material, usually offers the advantages of being easy to manufacture, usually having few impurities, and a large pore volume. As a result, porous carbon exhibits good electrical conductivity as well as high mechanical and chemical stability. In one embodiment, the carbon material has a high micropore volume ratio. Typically, porous carbon has a pore space, also referred to as pore volume, which is a group of voids (pores) in carbon that can be filled with gas or fluid. In this regard, the properties and manufacturing methods of porous carbon are described in the prior art, for example, Patent Document 1, the entire disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0064] The Si portion of the silicon-carbon composite material may be pure silicon or a material composition containing silicon. For example, the Si portion may be at least one alloy. The alloy may be a silicon-titanium alloy (Si-Ti), a silicon-iron alloy (Si-Fe), or a silicon-nickel alloy (Si-Ni). In a further embodiment, the Si portion may consist of a P-dopant, an As-dopant, or an N-dopant. A P-dopant is usually a phosphorus-dopant, an As-dopant is usually an arsenic-dopant, and an N-dopant is usually a nitrogen-dopant.

[0065] FIG. 1 is an exemplary diagram for explaining a method 1 for manufacturing a surface-coated lithium-silicon-carbon composite material 10 according to an embodiment of the present invention.

[0066] In a first method step 2, a porous carbon scaffold having micropores and mesopores is provided. The illustrated shapes and sizes of the porous carbon scaffold 20 and the lithium-silicon-carbon composite material 10 are intended for the explanation of method 1. The final shapes and sizes of the materials utilized may vary according to requirements.

[0067] In a further method step 3, a Li compound is introduced into the micropores and mesopores of the provided porous carbon scaffold 20 by a solution-based infiltration method. Then, in a further method step 4, the solvent of the solution-based infiltration method is removed to obtain or form a microporous and mesoporous carbon scaffold into which the Li compound 21 has been introduced. Thus, the porous carbon scaffold 20 is provided in a prelithiated form, such as a Li-Al alloy for example.

[0068] Furthermore, in method step 5, at least one additional compound containing Si and optionally at least one of Fe, Al, Ni, W, and / or Ti is introduced into the micropores and mesopores of the porous carbon scaffold by chemical vapor infiltration to form a lithium-alloy-carbon-silicon composite material 22. Preferably, SiH 4 is utilized as the additional compound for carrying out the chemical vapor infiltration process.

[0069] In the following method steps 5 and 6, a surface coating 11 is provided on at least a part of the surface area of the lithium-alloy-carbon-silicon composite material 22. At least one surface coating layer 12 of the surface coating contains silicon oxide, aluminum oxide, or zirconium oxide. The lithium-alloy-carbon-silicon composite material 22 is treated with a metal alkoxide or a metal amide or an alkyl metal compound to form a treated compound layer (not shown). In the illustrated embodiment, the surface area of the lithium-alloy-carbon-silicon composite material 22 is covered with trimethylaluminum TMA. During the exposure of the surface area to trimethylaluminum, it dissociatively chemisorbs onto the surface area of the lithium-alloy-carbon-silicon composite material 22, and any residual trimethylaluminum in the gas phase can be easily removed.

[0070] The dissociative chemisorption of trimethylaluminum TMA results in a treated compound surface covered with AlCH 3 . This treated compound surface is treated with water H 2 O or oxygen O 2 or ozone O 3 to form at least one first layer of the surface coating 12.

[0071] This first surface coating layer 12 consists of Al 3 O 2 because the CH 3 of the treated compound surface chemically reacts during the treatment. Such a coating can be provided, for example, by thermal atomic layer deposition which also requires a temperature increase up to 450 °C.

[0072] In any step 7, a treatment combining heating with Li-N(SiMe 3 ) 2 modifies the first surface coating layer 12 to a modified first surface coating layer 13 and enables it to contain Li in the form of LiAlO 2 O 3 in addition to Al 2 molecules. Such molecules having lithium Li can improve the kinetics of Li ions through the modified first surface coating layer 13.

[0073] In a further step 8, the second surface coating layer 14 can be applied on the first surface coating layer 13 which has been pre-modified to contain LiAlO 2 and Al 2 O 3 In the illustrated example, the second surface coating layer 14 is made of carbon C.

[0074] The first surface coating layer 13 and the second surface coating layer 14 form a surface coating 11 of a lithium-silicon-carbon composite material. In this way, after applying the surface coating 11, a surface-coated lithium-silicon-carbon composite material 10 formed as a lithium-alloy-silicon-carbon-silicon composite material in the illustrated embodiment is formed.

[0075] FIG. 2 shows a cross-sectional view of an exemplary electrochemical energy storage device 100 having an anode electrode 110 containing the surface-coated lithium-silicon-carbon composite material 10 manufactured by the method shown in FIG. 1.

[0076] The electrochemical energy storage device 100 is formed as a lithium-ion battery cell. The electrochemical energy storage device 100 includes at least one anode electrode 110, at least one cathode electrode 120, and a separator 130 disposed between the cathode electrode 120 and the anode electrode 110. The cathode electrode preferably contains a transition metal oxide.

[0077] Furthermore, an electrolyte 140 containing lithium ions is provided within the cell housing 150 of the electrochemical energy storage device 100. The electrochemical energy storage device 100 can be formed as a pouch-shaped lithium-ion battery cell. Accordingly, the cell housing 150 may be formed as an aluminum bag. The anode electrode 110, the cathode electrode 120, and the separator 130 are also disposed within the cell housing 150.

[0078] Note that FIG. 2 shows a simplified cross-sectional view. The anode electrode 110, the cathode electrode 120, and the separator 130 are typically formed as a plurality of layers that are wound or folded in order to optimize packaging and to increase the possible surface area of the electrolyte 140. In the illustrated example, only one layer of the components is shown for the sake of explanation.

[0079] The anode electrode 110 is coated on both sides with a surface-coated lithium-alloy-lithium-silicon-carbon composite material 10. The surface coating film 11 of the surface-coated lithium-silicon-carbon composite material 10 is performed on the surface region of the lithium-silicon-carbon composite material 10 that does not contact the current collector 111 of the anode electrode 110.

[0080] By using the anode electrode 110 having the surface-coated silicon-carbon material 10, the requirements for the dry chamber environment for manufacturing the electrochemical energy storage device 100 can be reduced. In particular, during the filling of the electrolyte 140 into the cell housing 150, the surface protection by the surface coating film 11 can reduce or prevent the chemical interaction between the anode electrode and contaminants.

[0081] FIG. 3 shows a further exemplary electrochemical energy storage device 100. The electrochemical energy storage device 100 contains an anode electrode 110 having a surface-coated lithium-silicon-carbon composite material 10. In contrast to the embodiment shown in FIG. 2, the surface coating film 11 of the lithium-silicon-carbon composite material 10 is partially applied to the surface of the lithium-silicon-carbon composite material 10 such that some portions of the surface region of the lithium-silicon-carbon composite material 10 remain without the surface coating film 11.

Claims

1. A lithium-silicon-carbon composite material (10) formed as a surface-coated lithium-silicon-carbon composite material, comprising: - A porous carbon support (20) containing micropores and mesopores and having a total pore volume of 0.5 cm ３ / g or more; - A silicon content of 30% to 70% including 30% and 70%; - A Li content of 2% to 20% including 2% and 20%; and - A first surface coating layer (12) that is at least partially coated and forms a surface coating film (11) on the surface region of the lithium-silicon-carbon composite material containing one or more elements from Li, B, Al, Si, P, Ti, Zr, Nb, and / or W Lithium-silicon-carbon composite material (10).

2. The material according to claim 1, wherein the at least partially coated first surface coating layer (12, 13) has a thickness in the range of 0.1 nm to 1 μm.

3. The material according to claim 1 or 2, wherein the first surface coating layer (12, 13) contains at least one metal oxide from the element group Li, B, Al, Si, P, Ti, Zr, Nb, and / or W.

4. The material according to any one of claims 1 to 3, wherein at least 50% of the surface region of the lithium-silicon-carbon composite material (10) is covered by the surface coating film (11).

5. The material according to any one of claims 1 to 4, wherein the surface coating film (11) of the lithium-silicon-carbon composite material (10) contains a second surface coating layer (14).

6. The material according to claim 5, wherein the second surface coating layer (14) is formed as a carbon coating.

7. The surface area of the lithium-silicon-carbon composite material (10) is 2 m ２ / g to 30 m ２ / g, particularly 4 m ２ / g to 10 m ２ / g, and the material according to any one of claims 1 to 6 is within the range.

8. The first surface coating layer (13) is LiAlO ２ or Li ２ ZrO ３ The material according to any one of claims 1 to 7, containing lithium in the form of molecules.

9. A method (1) for manufacturing a surface-coated lithium-silicon-carbon composite material (10) according to any one of claims 1 to 8, comprising: - Providing a porous carbon scaffold (20) having micropores and mesopores; - Introducing an Li compound into the micropores and mesopores of the provided porous carbon scaffold (20) via a solution-based infiltration method; - Removing the solvent to obtain a carbon scaffold having micropores and mesoporosity with the introduced Li compound (21); - Introducing at least one additional compound containing Si and Fe, Al, Ni, W, and / or Ti into the micropores and mesopores of the porous carbon scaffold by chemical vapor infiltration to form a lithium-alloy-carbon-silicon-composite material (22); - At least one surface coating layer (12, 13) containing silicon oxide, aluminum oxide or zirconium oxide is at least partially applied onto the surface region of a lithium - alloy - carbon - silicon composite material (22) to form a surface - coated lithium - silicon - carbon composite material (10). Method. Claim 10 LiAlH as a Li compound ４ The method according to claim 9, wherein ４ is introduced into the micropores and mesopores of the provided porous carbon scaffold (20) by a solution-based infiltration method. Claim 11 The method according to claim 9 or 10, wherein the at least one surface coating layer (12, 13) is at least partially applied onto the surface region of the lithium - silicon - carbon composite material (10) by a vapor deposition method. Claim 12 The lithium - alloy - carbon - silicon composite material (22) is treated with a metal alkoxide or a metal amide or an alkyl metal compound to form a treatment compound layer on the surface region, and the treatment compound layer on the surface region is treated with moisture or oxygen or ozone to form the at least one surface coating layer (12). The method according to any one of claims 9 to 11. Claim 13 The surface coating (11) of the surface region of the lithium - silicon - carbon composite material (10) contains lithium in the at least one surface coating layer (13) and / or as part of the lithium - silicon - carbon composite material (10). The method according to any one of claims 9 to 12. Claim 14 The surface coating (11) of the surface region of the lithium - silicon - carbon composite material (10) contains at least one metal oxide from at least one of the element groups Li, Al, Si, Zr, Nb and / or W. The method according to any one of claims 9 to 13. Claim 15 The method according to any one of claims 9 to 14, wherein the at least one surface coating layer (12, 13) is applied onto the surface region of the lithium - silicon - carbon composite material (10) at a temperature in the range of 25°C to 550°C. Claim 16 The method according to claim 12, wherein the treatment of forming a treatment compound layer by treating the lithium - alloy - carbon - silicon composite material (22) with a metal alkoxide or a metal amide or an alkyl metal compound and treating the treatment compound layer with moisture or oxygen or ozone is repeated at least once. Claim 17 The method according to any one of claims 12 or 16, wherein the treatment of the treatment compound layer with moisture or oxygen or ozone is carried out at a temperature in the range of 25°C to 450°C. Claim 18 An anode electrode (110) containing a current collector (111) and the surface-coated lithium-silicon-carbon composite material (10) according to any one of claims 1 to 8, wherein the surface-coated lithium-silicon-carbon composite material is disposed on at least one side of the current collector.

19. The anode electrode according to claim 18, wherein a surface region of the lithium-silicon-carbon composite material (10) not in contact with the current collector (111) is at least partially covered with a surface coating film (11) having a layer thickness in the range of 0.1 nm to 1 μm.

20. A method for manufacturing at least one anode electrode (110) according to claims 18 and 19, comprising: - A silicon-carbon composite material mixture, particularly a lithium-silicon-carbon composite material mixture, comprising at least one carbon compound; - Combining the silicon-carbon composite material mixture comprising the carbon compound with an aqueous and / or non-aqueous binder solution to form an electrode paste; - Applying the electrode paste to a current collector, such as a conductor foil; - Drying the current collector coated with the electrode paste at a temperature of 100°C to 140°C to form at least one anode electrode. Method.

21. A method for manufacturing at least one anode electrode (110) according to claim 17, comprising: - The silicon-carbon composite material mixture combined with the binder powder is at least partially applied to at least one surface of a current collector formed as a conductor foil (111) by calendering; - Drying the conductor foil (111) having the applied mixture at a temperature of 100°C to 140°C to form the at least one anode electrode (110). Method.

22. An electrochemical energy storage device (100), particularly formed as a lithium-ion battery, comprising: - At least one anode electrode (110) according to any one of claims 18 and 19; - At least one cathode electrode (120) containing a transition metal oxide; - A separator (130) disposed between the cathode electrode (120) and the anode electrode (110); and - An electrolyte (140) containing lithium ions An electrochemical energy storage device (100) containing.

23. The first surface coating layer (12, 13) contains a metal oxide from Li, especially Al ２ O ３ In addition, the material according to any one of claims 1 to 8.

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