PARTICULATED SILICON-CONTAINING ACTIVE MATERIAL, NEGATIVE ELECTRODE, LITHIUM-ION BATTERY CELL, VEHICLE AND METHOD FOR PRODUCING ACTIVE MATERIAL AND ELECTRODE

Description

[0001] The invention relates to a negative electrode with a particulate silicon-containing active material, a lithium-ion battery cell, a vehicle, and a method for producing the active material and the negative electrode.

[0002] Lithium-ion batteries (LIBs) are considered the key technology in electromobility. They are therefore subject to constant optimization with regard to their cost, weight, energy density, lifespan, safety, and charging time.

[0003] Typical lithium-ion batteries, or rather the corresponding lithium-ion cells, have two different electrodes: a negative electrode, also called the anode, and a positive electrode, also called the cathode. Each electrode consists of a current collector and at least one active material applied to it, as well as inactive materials such as binders and conductive carbon black. Between the electrodes is an ion-conducting electrolyte, which wets the electrodes and acts as a mediator of the processes within the cell, and a separator, which ensures the electronic separation of the electrodes. The terms anode and cathode are defined by the oxidation and reduction processes, respectively. Which of the two electrodes is oxidized or reduced depends on whether the battery / cell is being charged or discharged.However, when considering batteries, it has become customary to always use the discharge process as the definition for the terms anode and cathode.

[0004] The negative electrode of the cell typically consists of a copper foil (inactive material for current conduction) and a layer of graphite or lithium-alloyed material as the electrochemically active material. During charging, the positively charged lithium ions required for power generation are intercalated into this layer. Graphite anodes are currently the most common choice because they exhibit a low electrode potential and minimal volume expansion during the intercalation of Li⁺ / Li⁻ ions. The positive electrode consists of mixed oxides applied to an aluminum collector. The positive electrode serves as the lithium source during cell charging.

[0005] By varying the electrode materials, it is possible to increase the energy density of lithium-ion batteries and thus, for example, significantly extend the range of electric vehicles. Silicon is a suitable material in this respect. Compared to commercially used graphite, it has a specific capacity ten times higher and a similarly low lithiation potential (0.4 V vs. Li / Li+). Furthermore, since silicon is the second most abundant element in the Earth's crust, its production is inexpensive, and it is safe to handle and non-toxic, it is industrially attractive.

[0006] However, the commercial application of silicon-containing anodes is hampered by the very significant volume change of the anodes during the lithiation and delthiation processes (Li₁₅Si₄: 280–300%, compared to LiC₆: 10–11%). This "breathing" of the anodes leads to the pulverization of the active material particles within the anode and consequently to further problems. a) Negative effects on the preservation of the electrode architecture, which is particularly noticeable at high surface loadings. This results in contact losses within the electrode, as well as between the electrode and the current collector, and is reflected in a deterioration of electrical conductivity; b) a constantly rupturing and thus increasing solid electrolyte interphace (SEI), which in turn leads to continuous lithium-ion consumption, an increasing internal resistance in the cell, thus to low Coulombic efficiency (CE) and insufficient cycle stability.

[0007] The boundary layer (solid electrolyte interface, SEI) between the negative electrode and the electrolyte is formed during the cell's first cycles as a result of the reductive decomposition of various electrolyte components, such as solvents, additives, and impurities, which are thermodynamically and electrochemically unstable at the voltages reached. This formation process always results in an irreversible loss of capacity.

[0008] The formation of the SEI is essential for the functionality and lifespan of lithium-ion batteries (LIBs), as it ideally possesses good ionic conductivity while simultaneously acting as an electrical insulator. Through its kinetically limiting effect, it largely suppresses further electrolyte degradation and thus counteracts further capacity loss. Furthermore, the SEI acts as a "sieve," protecting the graphite layer structure from exfoliation and therefore the cell from significant capacity loss.

[0009] In the case of commercial graphite electrodes, the irreversible capacitance loss due to SEI formation is very low at approximately 2-5%, compared to 20-80% for silicon-based electrodes. In addition to the irreversible capacitance loss (ICL) during initial formation, silicon-based electrodes also suffer an additional capacitance loss due to significant "breathing" during cycling.

[0010] Therefore, a distinction is made between two different irreversible capacity losses (CL). a) "Initial CL" (ICL)

[0011] The ICL is subject to various influencing factors. It depends primarily on the form in which the silicon is used. This can vary in the type of material (Si alloy, composite, SiOx, coated Si), its shape, its crystallinity (amorphous, crystalline, or polycrystalline), and its particle size (nano-, micro-range, size distribution), and thus in its BET surface area. Specifically, particles in the nano-range have a larger active surface area and therefore a higher ICL. In this variant, the SEI is particularly low due to a constant current that is better distributed across the active surface.

[0012] ICL is caused by the activation of the material, which is more pronounced in the case of silicon than in the case of graphite.

[0013] Due to the significant difference in Coulombic efficiency (CE) during formation between the positive and negative electrodes, balancing the electrodes presents considerable challenges. An optimized capacity ratio is particularly important to minimize internal lithium loss and thus irreversible capacity loss. Even a difference in CE of 99.8% and 99.2% in a full cell is significant, as the CEs are already at 90.5% and 66.9%, respectively, after just 50 cycles. b) CCL (Continuous Capacity Loss)

[0014] As described, silicon-containing materials undergo significant volume expansion during lithiation and contraction during delthiation, leading to the breakdown of the SEI, which is too inflexible to accommodate the "breathing" of the particles. Due to the breakdown of the SEI, it no longer fulfills its kinetically limiting or sieving function. Consequently, a thermodynamically unstable system persists, and electrolyte and lithium are continuously consumed.

[0015] The continuous increase in SEI due to ongoing cell rupture leads not only to an increase in SEI resistance (or cell internal resistance) but also to an increase in the anode potential. This higher anode potential results in two things: firstly, a lower amount of lithiation occurs, thus reducing capacity; and secondly, it leads to an increase in the cathode potential to reach the full-cell cutoff voltage. This results in the degradation of the cathode structure and the oxidative decomposition of the electrolyte, consequently reducing the cell's lifespan. For long-term cycling, optimizing the anode-to-cathode capacity ratio (as in the case of ICL) is insufficient because the cell "breathes," the SEI continuously increases, and lithium is consumed.

[0016] To increase the service life of silicon-containing electrodes, in addition to the possibility of reducing the volume expansion of the silicon by optimizing the active material itself, there are also approaches to optimizing the binder and conductive carbon black components as well as the electrode recipe and to "refine" the surface of the active material.

[0017] In the "refinement" of the surface of the active material, an "artificial" SEI is formed, which can be produced by known coating processes such as CVD (chemical vapor deposition) and sputtering of surfaces.

[0018] Molecular layer deposition (MLD) and atomic layer deposition (ALD) stand out from these methods due to their ability to deposit thin, self-contained, homogeneous films of high quality and complex 3D structures. The coatings can be controlled at the atomic or molecular level. The gas-solid reaction is self-limiting and surface-saturated. Combining both processes allows for the creation of hybrid coatings whose mechanical and electronic properties can be tailored by selecting and combining precursors.

[0019] German patent application DE 10 2017 110 902 A1 describes an electroactive material for a lithium-ion battery for automotive applications, comprising silicon or tin. The material is provided with a polymer coating that can reversibly expand by at least 250% from a contracted state to an expanded state in at least one direction. The coating can be applied by ALD and can consist of siloxane, polycaprolactam, polyethylene oxide, an acrylate polymer, or a methacrylate polymer.

[0020] US 2004 / 0058232 A1 describes anodes of a lithium-ion battery that have a polymeric protective layer, wherein the protective layer contains organosulfur compounds as well as an electron-conducting and an ion-conducting polymer. The protective layer can also be doped with various metal salts, such as TiCl₄.

[0021] US patent 2017 / 0263935 A1 discloses anodes for a lithium-ion battery made of one or more metals from groups I and II. The anodes have a protective layer that may contain titanium or alucone. Furthermore, the protective layer may consist of multiple layers applied using ALD or MLD.

[0022] DE 10 2008 046 498 A1 discloses a negative electrode of a lithium-ion battery with an active layer forming a porous outer surface, wherein at least the outer surface of the active layer is coated at least partially with nanoparticles of either aluminium oxide or zirconium oxide.

[0023] German patent application DE 10 2014 118 089 A1 describes an electrode material for a negative electrode, comprising silicon as the active material, for use in an electrochemical cell. A nanocomposite surface coating for the negative electrode is provided, comprising carbon and a metal oxide of titanium, aluminum, tin, and mixtures thereof. This coating is intended to minimize charge capacity loss in the electrochemical cell. The coating can be applied using ALD (aluminum laser deposition).

[0024] WO 2015 / 021368 A1 describes a negative electrode of a lithium-ion battery, comprising a silicon plate with a porous surface arranged on a current collector. The porous surface of the silicon plate is coated with aluminum oxide such that the pores are filled to a predetermined depth of the plate. The coating is applied using aluminum oxide deposition (ALD) with trimethylaluminum as a precursor.

[0025] The object of the invention is to provide a negative electrode with a silicon-containing active material for a lithium-ion battery cell that expands during the lithiation cycle, which at least partially eliminates the disadvantages of the prior art, in particular with regard to capacity loss and charging capacity.

[0026] This problem is solved by a negative electrode of a lithium-ion battery cell with a particulate silicon-containing active material, a lithium-ion battery cell and a method for producing the negative electrode with the features of the independent claims.

[0027] The negative electrode for a lithium-ion battery cell comprises a collector (hereinafter also referred to as a current collector) and an electrode layer applied thereto, which has a particulate, silicon-containing active material. According to the invention, a surface of the particulate, silicon-containing active material or of the electrode layer is provided with a coating.The coating is deposited on the surface by ALD and / or MLD using at least one precursor selected from the following group: ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, heptanedioic acid, octanedioic acid, decanedioic acid, (E)-butenedioic acid, (Z)-butenedioic acid, benzoic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, (2E,4E)-hexa-2,4-diendicarboxylic acid, propane-1,2,3-tricarboxylic acid, (1E)-prop-1-ene-1,2,3-tricarboxylic acid, ethane-1,2-diamine, hexane-1,6-diamine. 4,4'-Oxydianilin, 4-Nitrobenzene-1,3-diamine, 1,4-Diaminobenzene, Furo[3,4-f][2]benzofuran-1,3,5,7-tetrone, Terephthalic acid dichloride, and / or Bis(hydroxyethyl)terephthalate.

[0028] In embodiments of the invention, one or more of the following precursors can additionally be used in ALD and / or MLD: Trimethylaluminium (TMA), Diethylzinc (DEZ), Titanium Tetrachloride (TiCl4).

[0029] In one embodiment, the active material of the electrode, or its individual particles, are completely surrounded by the coating.

[0030] An alternative negative electrode is provided according to the invention in which the electrode layer is first formed and then the electrode layer is coated on the surface using ALD and / or MLD with at least one of the aforementioned precursors. In this variant, only the accessible surfaces of the active material or the particles are coated.

[0031] The active material and negative electrodes according to the invention, which are produced using ALD and / or MLD with the aforementioned precursors, offer the advantage that the organic polymers or the covalently bonded inorganic / organic polymer chain accommodate the volume expansion of the silicon without breaking. This advantageously allows the lifetime of lithium-ion cells to be significantly increased compared to the prior art.

[0032] Preferably, the aforementioned precursors are combined as follows in the aforementioned processes (ALD / MLD) to obtain particularly preferred active materials or electrodes: MLD: Ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, heptanedioic acid, octanedioic acid, decanedioic acid, (E)-butenedioic acid, (Z)-butenedioic acid, benzoic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, (2E,4E)-hexa-2,4-dienedicarboxylic acid and / or propane-1,2,3-tricarboxylic acid and / or (1E)-prop-1-ene-1,2,3-tricarboxylic acid with trimethylaluminium (TMA) and / or diethylzinc (DEZ) and / or titanium tetrachloride (TiCl₄), and / or ALD: trimethylaluminium (TMA) and / or diethylzinc (DEZ) and / or titanium tetrachloride (TiCl₄) with H₂O, preferably in ratios of (MLD:ALD cycle) 1:1, 2:1 / 1:1, 3:2 / 2:1 / 1:1, 3:1, 4:1.6:3; or MLD: Ethane-1,2-diamine, Hexane-1,6-diamine, 4,4'-Oxydianiline, 4-Nitrobenzene-1,3-diamine and / or 1,4-Diaminobenzene with Furo[3,4-f][2]benzofuran-1,3,5,7-tetron, or MLD: Furo[3,4-f][2]benzofuran-1,3,5,7-tetron, (E)-Butenedioic acid, (Z)-Butenedioic acid, (2E,4E)-Hexa-2,4-diendicarboxylic acid, Terephthalic acid dichloride, 1,2 Benzenedicarboxylic acid, Phthalic acid, 1,3 Benzenedicarboxylic acid, Isophthalic acid, 1,4 Benzenedicarboxylic acid, Terephthalic acid, (1E)-Prop-1-ene-1,2,3-tricarboxylic acid, 1,3,5-Benzenetricarboxylic acid, 1,2,4,5-Benzenetetracarboxylic acid and / or bis(hydroxyethyl)terephthalate with trimethylaluminium (TMA) and / or diethylzinc (DEZ) and / or titanium tetrachloride (TiCl₄); and / or ALD: trimethylaluminium (TMA) and / or diethylzinc (DEZ) and / or titanium tetrachloride (TiCl₄) with H₂O, preferably in ratios of (MLD:ALD cycle) 1:1, 2:1 / 1:1, 3:2 / 2:1 / 1:1, 3:1, 4:1, 6:3.

[0033] The thickness of the layer can be adjusted by the number of ALD and / or MLD cycles performed. Preferably, the layer thickness is between 2 nm and 500 nm.

[0034] The process steps of ALD and MLD are generally known to those skilled in the art.

[0035] By selecting the precursors and arranging the individual deposited layers relative to each other, the properties of each layer can advantageously be optimally adjusted to the respective application.

[0036] Thus, polymer chains or branched / crosslinked polymer structures can be created by appropriately selecting precursors.

[0037] A hardness gradient can preferably be set by decreasing the organic proportion of the precursors with increasing distance from the surface of the active material and by having a higher proportion of inorganic precursors.

[0038] Since silicon compounds and those contained in the solid electrolyte interface have a relatively high modulus of elasticity and are therefore very stiff (Li 2 Si 2 O 5 = 135 GPa, Li 4 SiO 4 = 120 GPa, Li 2 O = 141 GPa, SiO 2 = 70 GPa), it is preferred to provide a modulus of elasticity towards the electrode that is in the range of 50-150 GPa and that towards the electrolyte is preferably less than 50 GPa.

[0039] A gradient of the modulus of elasticity within the coating can be set by combining MLD and ALD cycles.

[0040] Preferably, organic and inorganic layers are applied alternately to stabilize the individual layers.

[0041] For example, an MLD cycle is performed using TiCl4 +EG (lower modulus of elasticity), followed by an ALD cycle (TiCl4 + H2O) and then at least one MLD cycle using TiCl4 +GL (higher modulus of elasticity).

[0042] The following are various possible combinations of ALD and MLD, preferably for setting an E-module: Elektrodenoberfläche Electrolyte 1:1 (MLD:ALD+MLD) | 2:1 (MLD:ALD+MLD) |1:1 3:2 (MLD:ALD+MLD) |2:1 (MLD:ALD+MLD) |1:1 (MLD:ALD+MLD) 3:1 (MLD:ALD+MLD) 4:1 (MLD:ALD+MLD) 6:3 (MLD:ALD+MLD) |2:1

[0043] The advantages of the coating or the artificial SEI are as follows: The layer can be kept very thin compared to natural SEI because defined molecular layers are deposited using ALD and MLD / MLD processes. The ionic conductivity is optimized compared to natural SEI, as the properties can be precisely adjusted by selecting the precursors. Flexibility (Young's modulus) and low resistance are inherent and correlate with the choice and combination of materials, and are therefore adjustable. Good adhesion to the electrode is achieved because covalent bonds are formed by the chosen deposition methods.

[0044] Otherwise, when selecting precursors and planning the design, it is important to choose materials with sufficient vapor pressure, sufficient reactivity towards the other components in the operating temperature window, and thermal stability.

[0045] For electrode coatings, the temperature is limited by the decomposition temperature of a binder. Therefore, when using organic acids such as PAA (polyacrylic acid) or CMC (carboxymethylcellulose), this temperature should not exceed 150°C.

[0046] Unlike electrode coating, the temperature selection for coating the active material is not critical and depends on the vapor pressure, as already described, and the decomposition temperature of the precursors themselves.

[0047] To increase the reaction rate, the components should not be too bulky for steric reasons, should have two different functional groups and / or an organic ring, and should have a stiff backbone.

[0048] The silicon-containing active material is preferably selected from the following group: nano-silicon, silicon-carbon composites, silicon oxides, uncoated or carbon-coated, binary and ternary silicon alloys, preferably Si-Sn, Si-Sn-Fe, Si-Sn-Al, Si-Fe-Co, Si-Ag, Si-Zn, Si-Al, silicides, preferably FeSi₂, Mg₂Si; CaSi₂, prelithized silicon, preferably each with a silicon content of 1 wt% to 95 wt%. These particles are preferably processed using a binder and conductive carbon black.

[0049] In other embodiments, the active material can comprise silicon and be in the form of nanowires, nanorods, nanofibers, or hollow tubes. Such silicon structures can help to contain the large volume changes that silicon undergoes during lithium cycling in a lithium-ion battery. In certain variations, the silicon structure can also include a carbon material deposited on it. The aforementioned nanostructures fall under the term particles. Preferably, these particles can be deposited directly onto the current collector by CVD without additional inactive materials such as binders and conductive carbon black.

[0050] Preferably, the mean particle size (X50) of the active material is in the range of 30 nm to 20.0 µm. Crystalline silicon is preferably smaller than 150 nm and amorphous silicon smaller than 870 nm.

[0051] The invention relates to negative electrodes, as described, which comprise the aforementioned active material and inactive materials, such as the collector, wherein the active material is applied to the collector.

[0052] A metal with good conductivity is typically used as the collector. Suitable materials are generally known to experts.

[0053] As previously described, the electrode particles may have been coated before their manufacture, or the area (visible area) of the electrode that comes into contact with the electrolyte may be coated. Ideally, the entire internal porous structure of the electrode, up to the collector (terminator), is then coated.

[0054] An electrode layer according to the invention comprises 1-95% silicon; 0-95% graphite; 1-20% conductive additive (carbon nanotubes, vapor-grown nanotubes, multiwall nanotubes, SP); 1-20% binder (carboxymethylcellulose, styrene-butadiene rubber, carboxymethylcellulose with styrene-butadiene rubber, polyacrylic acid, polyacrylic acid with styrene-butadiene rubber, carboxymethylcellulose with polyacrylic acid, carboxymethylcellulose with polyacrylic acid and styrene-butadiene rubber, alginates, carboxymethylcellulose with polyacrylic acid and polyalkyl methacrylate).

[0055] Carbonanotubes are preferred as conductive additives, and polymeric carboxylic acids such as CMC (carboxymethylcellulose), PAA (polyacrylic acid) and alginates, as well as carboxymethylcellulose with styrene-butadiene rubber or polyacrylic acid, are preferably used as binder components in electrode manufacturing, since these exhibit good adhesion to the active and inactive material as well as good mechanical properties according to their field of application.

[0056] Due to its mechanical properties, this layer has the potential to preserve the structure of the negative electrodes. This counteracts capacity loss resulting from SEI replication. Electrode fabrication can be improved and potentially shortened by using such precursors, which are also known as dispersants and act as such during production. Furthermore, some of these precursors possess a conjugated electron system, which offers the potential for good electronic conductivity. Lithium-ion conductivity is enabled by carboxyl groups and similar components. Therefore, such a coating offers the potential to increase the fast-charging capability of battery cells.

[0057] The invention further relates to a lithium-ion battery cell with at least one of the aforementioned negative electrodes, and to a vehicle having at least one lithium-ion battery cell according to the invention. The term "vehicle" refers in particular to single-track or two-track electric vehicles.

[0058] A method for producing a negative electrode according to the invention for a lithium-ion battery cell is also claimed, comprising the following steps: a) Providing at least one negative electrode or active material, b) Coating the at least one negative electrode or active material using an MLD and / or ALD coating process and / or a combination of MLD and ALD coating processes using the precursors described above, and c) Obtaining at least one coated negative electrode and / or coated active material.

[0059] The statements made regarding the individual subject matter of the invention apply analogously to all subject matter of the invention, even if this is not explicitly stated.

[0060] Unless otherwise stated in individual cases, the various embodiments of the invention mentioned in this application can be advantageously combined with one another.

[0061] Further preferred embodiments of the invention result from the other features mentioned in the dependent claims.

[0062] The invention is explained below using exemplary embodiments with reference to the accompanying drawings. These show: Figure 1 shows a schematic representation of a prior art lithium-ion cell, Figure 2 shows a schematic representation of a cutaway detail view of the negative electrode according to the invention, and Figure 3 shows a schematic representation of a cutaway detail view of the negative electrode according to a second embodiment.

[0063] Figure 1Figure 1 shows a lithium-ion cell 10 according to the invention, which has two different electrodes: a negative electrode 11, also called the anode, and a positive electrode 12, also called the cathode. The terms anode and cathode are actually defined by the oxidation and reduction processes, respectively. However, whether oxidation or reduction is currently taking place at an electrode 11, 12 depends on whether the lithium-ion cell 10 is being charged or discharged. It is therefore customary to use the discharge process as the basis for the designations anode and cathode. Accordingly, the electrodes 11, 12 are also named in this description. The electrodes 11, 12 consist of a collector 112, 122 and an active material 111, 121 applied thereto. The silicon-containing and particulate active material according to the invention is used for the negative electrode 11.Between the electrodes 11, 12, an ion-conducting electrolyte 13, which serves as a mediator for the processes in the lithium-ion cell 10, and a separator 14 are arranged, which ensures the electronic separation of the two electrodes 11, 12 and is permeable to charge carriers. Suitable electrolytes 13 and materials for separators 14 are known to those skilled in the art. Polymer membranes or ceramic materials, as well as nonwovens and glass fiber separators, are used as separators 14.

[0064] Typically, the so-called solid electrolyte interphase (SEI) forms on the negative electrode 11 in the electrolyte. This layer protects against the electrolyte 14 but is permeable to lithium ions 15. In the present invention, such a layer is artificially applied to the active material of the electrode. This is in Figure 1 not shown.

[0065] The negative electrode 11 of the Li-ion cell 10 consists, for example, of a copper foil as collector 112 and a layer of the active material 111 with various other components commonly used to manufacture electrodes.

[0066] During charging, the positively charged lithium ions 15 required for power provision are stored in the active material 111.

[0067] The positive electrode 12 typically consists of lithium mixed oxides, preferably cobalt, manganese, or nickel, or of phosphates, which are applied to an aluminum foil as a collector 122. The positive electrode 12, or rather its active material 121, serves as the source of the lithium ions 15 when charging the Li-ion cell 10.

[0068] During unloading, as in Figure 1As shown, lithium ions 15 migrate from the negative electrode 11 through the electrolyte 13 and the separator 14 to the positive electrode 12. The associated oxidation process releases electrons. These flow from the negative electrode 11 via an electrical connection 16, in which an electrical load is located, to the positive electrode 12, where a reduction process takes place and electrons are absorbed. The lithium-ion cell 10 has a casing 18.

[0069] In Figure 2A sectioned detail view of a negative electrode 11 is shown. A layer of a silicon-containing active material 111 is deposited on a collector 112. This layer is in turn coated with a layer / artificial solid electrolyte interphase 113, which consists of a plurality of alternately deposited layers of precursors. By selecting the precursors and depositing them in a defined sequence, the material properties of the layer / artificial solid electrolyte interphase 113 can be determined.

[0070] As in Figure 3As shown, a hardness gradient, symbolized by arrow 114, can be created in layer 113 by decreasing the organic proportion of the precursors with increasing distance from the surface of the active material 111 and by increasing the proportion of inorganic precursors. This layer 113 naturally also exists in individual layers; however, a different representation was chosen to illustrate the gradient. Reference symbol list

[0071] 10 Li-ion cell 11 Negative electrode / anode 111 Active material 112 Collector 113 Layer / artificial solid electrolyte interphase 114 Arrow 12 Positive electrode / cathode 121 Active material 122 Collector 123 Conductive layer 13 Electrolyte 14 Separator 15 Lithium ions 16 Conductor 17 Consumer 18 Housing

Claims

1. Negative electrode (11) for a lithium-ion battery cell (10), comprising a collector (112) and an electrode layer applied thereto which comprises a particulate, silicon-containing active material (111), wherein the surface of the active material (111) or of the electrode layer is provided with a coating (113) deposited on the surface by ALD and / or MLD using at least one precursor selected from the group of: ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, heptanedioic acid, octanedioic acid, decanedioic acid, (E)-butenedioic acid, (Z)-butenedioic acid, benzoic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, (2E,4E)-hexa-2,4-dienedicarboxylic acid, propane-1,2,3-tricarboxylic acid, (1E)-prop-1-ene-1,2,3-tricarboxylic acid, ethane-1,2-diamine, hexane-1,6-diamine, 4,4'-oxydianiline, 4-nitrobenzene-1,3-diamine, 1,4-diaminobenzene, furo[3,4-f][2]benzofuran-1,3,5,7-tetrone, terephthaloyl dichloride, and / or bis(hydroxyethyl) terephthalate.

2. Negative electrode (11) according to Claim 1, wherein the coating (113) deposited by ALD and / or MLD is further formed using at least one additional precursor selected from the group of: trimethylaluminum (TMA), diethylzinc (DEZ), titanium tetrachloride (TiCl4).

3. Negative electrode (11) according to Claim 1 or 2, wherein the individual particles of the silicon-containing active material (111) are completely surrounded by the coating (113).

4. Negative electrode (11) according to Claim 1 or 2, wherein only the accessible surfaces of the particles of the silicon-containing active material (111) applied to the collector (112) are coated with the coating (113).

5. Negative electrode (11) according to any of the preceding claims, wherein the precursors are combined as follows for ALD and / or MLD: MLD: ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, heptanedioic acid, octanedioic acid, decanedioic acid, (E)-butenedioic acid, (Z)-butenedioic acid, benzoic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, (2E,4E)-hexa-2,4-dienedicarboxylic acid, propane-1,2,3-tricarboxylic acid and / or (1E)-prop-1-ene-1,2,3-tricarboxylic acid combined with trimethylaluminum (TMA) and / or diethylzinc (DEZ) and / or titanium tetrachloride (TiCl4), and / or ALD: trimethylaluminum (TMA) or diethylzinc (DEZ) or titanium tetrachloride (TiCl4) with H2O, or MLD: ethane-1,2-diamine, hexane-1,6-diamine, 4,4'-oxydianiline, 4-nitrobenzene-1,3-diamine and / or 1,4-diaminobenzene combined with furo[3,4-f][2]benzofuran-1,3,5,7-tetrone, or MLD: furo [3, 4-f] [2]benzofuran-1, 3, 5, 7-tetrone, (E) - butenedioic acid, (Z)-butenedioic acid, (2E,4E)-hexa-2,4-dienedicarboxylic acid, terephthaloyl dichloride, 1,2-benzenedicarboxylic acid, phthalic acid, 1,3-benzenedicarboxylic acid, isophthalic acid, 1,4-benzenedicarboxylic acid, terephthalic acid, (1E)-prop-1-ene-1,2,3-tricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid and / or bis(hydroxyethyl) terephthalate combined with trimethylaluminum (TMA) and / or diethylzinc (DEZ) and / or titanium tetrachloride (TiCl4); and / or ALD: trimethylaluminum (TMA) or diethylzinc (DEZ) or titanium tetrachloride (TiCl4) combined with H2O.

6. Negative electrode (11) according to any of the preceding claims, wherein in the deposition the precursors and the sequence thereof are selected so as to result in a hardness gradient.

7. Negative electrode (11) according to any of the preceding claims, wherein the silicon material is selected from the group of: nanosilicon, silicon-carbon composites, silicon oxides, uncoated or carbon-coated, doped, silicon alloys, preferably with silver, zinc, aluminum, silicides, preferably FeSi2, Mg2Si; CaSi2, prelithiated silicon, preferably in each case having a silicon content of 1 wt% to 95 wt%.

8. Negative electrode (11) according to any of the preceding claims, wherein the active material (111) has an average particle size (X50) in the range from 30 nm to 20.0 µm.

9. Negative electrode (11) according to any of the preceding claims, wherein the electrode layer comprises 1-95% silicon; 95-0% graphite; 1-20% conductivity additive and 1-20% binder.

10. Lithium-ion battery cell (10) comprising at least one negative electrode (11) according to any of Claims 1 to 9.

11. Vehicle comprising at least one lithium-ion battery cell (10) according to Claim 10.

12. Process for producing a negative electrode (11) for a lithium-ion battery cell (10) according to any of Claims 1, 2 and 4 to 9, comprising the steps of: a) providing a particulate, silicon-containing active material (111), b) coating a surface of the active material (111) by an MLD and / or ALD coating process and / or a combination of MLD and ALD coating processes using at least one precursor selected from the group of: ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, heptanedioic acid, octanedioic acid, decanedioic acid, (E) -butenedioic acid, (Z) -butenedioic acid, (2E,4E) - hexa-2,4-dienedicarboxylic acid, propane-1,2,3-tricarboxylic acid, (1E)-prop-1-ene-1,2,3-tricarboxylic acid, benzoic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, ethane-1,2-diamine, hexane-1,6-diamine, 4,4'-oxydianiline, 4-nitrobenzene-1,3-diamine, 1,4-diaminobenzene, furo[3,4-f][2]benzofuran-1,3,5,7-tetrone, terephthaloyl dichloride, and / or bis(hydroxyethyl) terephthalate, and c) applying the coated active material (111) to a collector (112).

13. Process for producing a negative electrode (11) for a lithium-ion battery cell (10) according to any of Claims 1, 3 to 9, comprising the steps of: a) providing an electrode layer of a particulate, silicon-containing active material (111) on a collector (112), and b) coating a surface of the electrode layer by an MLD and / or ALD coating process and / or a combination of MLD and ALD coating processes using at least one precursor selected from the group of: ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, heptanedioic acid, octanedioic acid, decanedioic acid, (E) -butenedioic acid, (Z) -butenedioic acid, (2E,4E) - hexa-2,4-dienedicarboxylic acid, propane-1,2,3-tricarboxylic acid, (1E)-prop-1-ene-1,2,3-tricarboxylic acid, benzoic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, ethane-1,2-diamine, hexane-1,6-diamine, 4,4'-oxydianiline, 4-nitrobenzene-1,3-diamine, 1,4-diaminobenzene, furo[3,4-f][2]benzofuran-1,3,5,7-tetrone, terephthaloyl dichloride, and / or bis(hydroxyethyl) terephthalate.