Current collectors, associated sets and storage devices

Abstract

To supply a collector of an electrochemical drive device.SOLUTION: A collector (22) of an electrochemical drive device is covered with an interface layer (20). The interface layer (20) is formed by covering a composition on a collector (22). The composition is formed by particles and the collector of the electrochemical drive device with a volume average diameter in which at least 50% of the particles is 10 micrometer or less is supplied.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to coated current collectors and to assemblies and storage devices including such current collectors. [Background technology]

[0002] An electrochemical storage battery conventionally includes at least four elements: a positive electrode, a negative electrode, an electrolyte, and a current collector for each electrode. The assembly of the negative electrode and the current collector forms the anode, and the assembly of the positive electrode and the current collector forms the cathode.

[0003] The working principle of these batteries is based on the reversible storage of electrical energy into chemical energy by using two separate but coupled electrochemical reactions. The positive and negative electrodes, immersed in an electrolyte, are the sites of electrochemical reactions called Faraday reactions. The electrodes are made of active materials that allow them to store and release ions through oxidation and reduction reactions.

[0004] During discharge, the active material at the negative electrode oxidizes and releases some of the electrons that are carried towards the external circuit by the current collector, and releases cations that migrate towards the positive electrode through the electrolyte. The electrons then pass through a circuit that utilizes their energy, and the cations are captured by the active material at the positive electrode and reduced. The energy density that a battery can deliver depends on both the potential and the capacity of the electrochemical cell, both of which are directly related to the chemical properties of the system. The voltage of the battery is determined by the potential difference between the simultaneous redox reactions at the positive and negative electrodes.

[0005] The electrode is made according to a composition that mainly comprises one or more active materials (>90% by weight), conductive particles that ensure good transport of electrons to the active material set, and a binder that makes it possible to ensure adhesion to the substrate and cohesion of the particles.

[0006] The whole is generally produced in the form of a formulation including at least one solvent making it possible to coat the electrodes.

[0007] The two positive and negative electrodes are then ionically bound together by an electrolyte, which can be a liquid, gel, or solid.

[0008] Due to the inherent migration action of ions in batteries, their electrodes require materials that can insert or remove ions. Therefore, much development is being done to optimize these electrodes and obtain higher specific energy density and power output. The selection criteria are primarily based on the available capacity and the operating potential - i.e. the available energy - but also on power or safety and cost of materials.

[0009] Mass energy or specific energy is defined as the ratio between the retrievable energy at a certain rating (discharge C-rate at which the battery is discharged) and the mass of the battery. Mass energy is expressed in Wh / kg.

[0010] This concept is particularly useful for sizing batteries that are integrated into systems where mass is the dominant sizing criterion.

[0011] Volumetric energy is the ratio between the retrievable energy at a given rating and the volume of the battery. It is expressed in Wh / L. This concept is useful for sizing stationary batteries, since in stationary battery applications volume is often the more decisive criterion than mass.

[0012] Lithium technologies have the best properties in terms of mass and volumetric energy density, and therefore are the preferred technology of choice for portable applications such as mobile phones and laptop computers.

[0013] However, for certain applications, particularly in the automotive sector, the voltage limitation of such typical batteries to voltages below 3.5 volts (V) is problematic, and it is therefore desirable to use batteries of the lithium-ion type having a higher voltage, particularly around 4.2 volts (V).

[0014] With such a large increase in voltage, the corrosion phenomenon becomes more pronounced.

[0015] To address these issues, US Patent Application Publication No. 2012 / 0121974 proposes a combination of two elements. According to the first element, the cathode current collector is protected by a porous protective conductive coating. The porous coating contains carbon or conductive graphite. The protection against corrosion is achieved by using a conductive material, in particular LiBOB and LiPF 6 This also involves improving the electrolyte by adding additives such as:

[0016] However, improving the electrolyte is costly on the one hand and affects the performance of the battery on the other hand. Summary of the Invention

[0017] There is therefore a need for a current collector for an electrode that is capable of delivering higher voltages than those delivered by the prior art, in particular voltages higher than 3.5 volts, while obtaining batteries with better performance levels.

[0018] In fact, the choice of corrodible materials allows one to target better performance levels in terms of potential. It is advantageous for battery manufacturers to develop electrochemical systems from improved current collectors, so that the properties are stable over time.

[0019] To that end, the present disclosure relates to a current collector of a device for storing electrical energy, the current collector being coated with an interfacial layer, the interfacial layer being formed by coating a second composition (the composition being second according to the nomenclature of the present specification) on the current collector, the composition being formed by particles, at least 50% of the particles having a volume average diameter of 10 micrometers or less.

[0020] By the phrase "formed by" it should be understood that "consists of" i.e. in this context the diameter of the particle is measured at the time of insertion, but not at the time of composition after the information.

[0021] According to particular embodiments, the current collector comprises one or more of the following characteristics, taken alone or according to any technically possible combination: The interfacial layer is a layer that acts as a physical barrier to the access of corrosion-causing ions. The interface layer is a layer that prevents oxidation of the current collector even when the operating potential of the device for storing electrical energy is equal to or greater than the oxidation potential of the material of the current collector. the current collector is adapted for a device for storing electrical energy, comprising an electrolyte comprising an ionic salt selected from lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI), lithium bis(fluorosulfonyl)imide salt (LiFSI), lithium trifluoromethane-sulfonate salt (LiTF), lithium tetrafluoroborate salt (LiBF4), lithium bis(oxalato)borate salt (LiBOB), lithium difluoro(oxalato)borate salt (LiDFOB) and mixtures thereof; - ion salt is lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI) At least 90% of the particles have a volume mean diameter of 15 micrometers or less. - At least 99% of the particles have a diameter less than or equal to 10 micrometers The composition comprises a conductive material and a bonding material. the second composition consists of a conductive additive, a solvent and a binder material, the conductive material comprises at least one member selected from the list consisting of carbon, carbon black, graphite, graphene, carbon nanotubes, activated carbon fibers, and non-activated carbon nanofibers. the interface layer has a thickness of 1 micrometer or more the interface layer (20) has a thickness of less than or equal to 4 micrometers, preferably less than or equal to 2 micrometers;

[0022] The present disclosure also describes an assembly forming an anode or cathode that includes an electrode and a current collector, as described above.

[0023] The present disclosure also relates to an electrical energy storage device, an electrochemical accumulator or a supercapacitor, comprising the aforementioned assembly.

[0024] Other characteristics and advantages of the invention will become apparent on reading the following description of embodiments of the invention, given purely by way of example and with reference to the drawings, in which: [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram of a storage battery including an anode and a cathode; [Diagram 2] FIG. 2 is a schematic cross-sectional side view of the cathode of the storage battery of FIG. 1; [Diagram 3] FIG. 3 is a scanning electron microscope photograph of a coated current collector according to the prior art; and [Figure 4] FIG. 4 is a scanning electron microscope photograph of the coated current collector used to form the cathode of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Battery 10 is intended to be linked with other electrical batteries to form a generator of desired voltage and capacity.

[0027] Battery 10 uses reversible energy conversion techniques to store energy for later retrieval.

[0028] Battery 10 utilizing the electrochemical reactions described, battery 10 is an electrochemical battery.

[0029] Battery 10 includes an electrolyte 12 , an anode 14 , and a cathode 16 .

[0030] Typically, the electrolyte 12 is composed of different ionic salts that contribute ions used for charge storage or faradaic reactions, carbonates and a solvent or mixture of solvents that allow the solubilization of the ions.

[0031] The electrolyte 12 is composed of different ionic salts that contribute ions used for charge storage or faradaic reactions, carbonates and a solvent or mixture of solvents that allows the solubilization of ions.

[0032] Preferably, the ionic salt is selected from lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI), lithium bis(fluorosulfonyl)imide salt (LiFSI), lithium trifluoromethane-sulfonate salt (LiTF), lithium tetrafluoroborate salt (LiBF4), lithium bis(oxalato)borate salt (LiBOB), lithium difluoro(oxalato)borate salt (LiDFOB) and mixtures thereof.

[0033] The carbonate is, for example, propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) or diethyl carbonate (DEC).

[0034] It is also possible to find in smaller proportions methyl acetate or formate, acetonitrile, tetrahydrofuran or γ-butyrolactone, as well as binary or ternary mixtures or quaternary mixtures thereof, as well as ionic liquids.

[0035] Typically, the anode 14 is made of an ion insertion material, such as carbon in lithium-ion batteries, which is primarily used in the form of "mesocarbon microbeads" (MCMB), graphite, either man-made or natural, or lithium titanate (Li 4 Ti 5 O 12 or LTO), silicon, tin, or alloy-based graphitic materials such as soft or hard carbon or other types of anode materials.

[0036] The cathode 16 is shown in more detail in FIG.

[0037] Cathode 16 includes an electrode 18 , a current collector 22 , and an interfacial layer 20 .

[0038] The current collector 22, interface layer 20 and electrode 18 form a stack of layers with a stacking direction designated Z.

[0039] The electrodes 18 are in contact with the electrolyte 12 .

[0040] The electrode 18 is made from a first composition C1, the properties of which are now described.

[0041] The first composition C1 includes a first intercalation material MI1, a first binder material ML1 and a first conductive additive AC1.

[0042] The intercalation material is also called the "active material."

[0043] In lithium-ion accumulators, the active material MI1 of the electrode 18 is conventionally, for example, LiCoO 2 (LCO), LiNiMnCoO 2 (NMC), LiNiCoAlO 2 (NCA), LiMn 2 O 4 (LMO), LiFePO 4 (LFP), Li(LiNiMn)O 2or LiNiMnO (LNMO); LiS. Other examples of active materials for electrode 18 are possible, e.g., for sodium-ion batteries, such examples are described in the publication "Advanced Organic Electrode Materials for Rechargeable Sodium-Ion Batteries" Zhao, Q., Lu, Y., & Chen, J. Advanced Energy Materials (2016).

[0044] The choice of the first bonding material ML1 can vary considerably, as long as it is inert to the other materials of the electrode. The first bonding material ML1 is typically a polymeric material, which allows to facilitate the use of the electrodes during their manufacture. The first bonding material ML1 typically comprises one or several polymers selected from among thermoplastic polymers, thermosetting polymers, elastomers and mixtures thereof.

[0045] Examples of thermoplastic polymers include, but are not limited to, polymers derived from the polymerization of aliphatic or alicyclic vinyl monomers, such as polyolefins (including polyethylene or polypropylene), polymers derived from the polymerization of aromatic vinyl monomers, such as polystyrene, polymers derived from the polymerization of acrylic monomers and / or methacrylates, polyamides, polyether ketones, polyimides.

[0046] Examples of thermosetting polymers include, but are not limited to, thermosetting resins (such as epoxide resins or polyester resins) optionally mixed with polyurethanes or polyol polyethers, or vice versa.

[0047] Examples of elastomeric polymers include, but are not limited to, natural rubber, synthetic rubber, styrene-butadiene copolymers (also abbreviated as "SBR"), ethylene-propylene copolymers (also abbreviated as "EPM"), and silicones.

[0048] The first binding material ML1 can be a mixture of a thermoplastic polymer, a thermosetting polymer, and / or an elastomeric polymer.

[0049] Other suitable first binding materials ML1 include cross-linked polymers such as those made from a polymer having a carboxyl group and a cross-linking agent.

[0050] The first conductive additive AC1 includes one or several types of conductive elements for improving electron conductivity.

[0051] Examples of conductive elements include, but are not limited to, conductive carbon, graphite, graphene, carbon nanotubes, activated carbon fibers, non-activated carbon nanofibers, metal flakes, metal powders, metal fibers, and conductive polymers.

[0052] As an example, the thickness e18 of the electrode 18 is 50 μm.

[0053] The current collector 22 has sufficient conductivity to ensure the transport of electrons and is made of a light, fine, and mechanically strong material to function as the substrate of the electrode 18.

[0054] For example, the current collector 20 is a metal strip made of iron, copper, aluminum, nickel, titanium, or stainless steel.

[0055] Preferably, the current collector 20 is a metal strip made of aluminum.

[0056] As an example, the thickness e22 of the current collector 22 is 20 μm.

[0057] The interface layer 20 forms the interface between the current collector 22 and the electrode 18.

[0058] This means that, in particular, the interface layer 20 is a layer that contacts the current collector 22 on one hand and the electrode 18 on the other hand.

[0059] The interfacial layer 20 is coated onto a current collector 22 .

[0060] The interface layer 20 has a thickness e20 of 1 micrometer (μm) or greater.

[0061] Preferably, the interface layer 20 has a thickness e20 of 2 μm or greater.

[0062] Advantageously, the interface layer 20 has a thickness e20 between 1 μm and 4 μm.

[0063] The interface layer 20 is made according to a second composition C2.

[0064] The second composition C2 includes a second binder material ML2 and a second conductive additive AC2.

[0065] Advantageously, the second composition C2 consists of a second binding material ML2, a second conductive additive AC2 and a second solvent S2.

[0066] In each of the foregoing cases, the second composition C2 comprises a plurality of particles.

[0067] Such particles can have all types of shapes. Preferably, the particles are spherical.

[0068] The diameter of each particle is defined as the maximum distance between two points on the surface of the particle.

[0069] The diameter is measured, for example, by laser particle size analysis techniques.

[0070] Laser diffraction particle size measurement determines the particle size distribution of particles by measuring the angular change in scattered light intensity as a laser beam passes through a sample of dispersed particles: larger particles scatter light at small angles to the laser beam, and smaller particles scatter light at large angles.

[0071] Among the particles of the second composition C2, some of the particles have a volume average diameter less than or equal to the threshold diameter.

[0072] In either case, at least 50% of the particles have a volume mean diameter (referred to as Dv50) less than or equal to 10 micrometers.

[0073] Volume mean diameter is a particle size distribution parameter (see especially page 10 of "The Essential Guide to Particle Characterization" published by Malvern Instruments Limited in 2012).

[0074] The volume average diameter (e.g. Dv50) of the particles can be measured by static light using commercial particle sizers such as Malvern's MasterSizer3000 machine. The data are processed based on the Mie scattering theory to calculate the particle size distribution of the particles based on a spherical model of equivalent volume. More specifically, this theory, which is accurate for isotropic particles, makes it possible to determine the "effective" particle diameter in the case of non-spherical particles. This theory is described, among others, in the publication by van de Hulst (HC), "Light Scattering by Small Particles", chapters 9 and 10, New York, Wiley, 1957.

[0075] According to a first example, the proportion is greater than or equal to 90% and the threshold diameter is less than or equal to 30 μm, preferably less than or equal to 20 μm, even more preferably less than or equal to 10 μm.

[0076] Advantageously, the threshold diameter is less than or equal to 5 μm.

[0077] Thus, according to this first example, at least 90% of the particles have a volume mean diameter less than or equal to 30 micrometers (called Dv90).

[0078] According to a second example, the proportion is greater than or equal to 99% and the threshold diameter is less than or equal to 40 μm, preferably less than or equal to 30 μm, even more preferably less than or equal to 20 μm.

[0079] Advantageously, the threshold diameter is less than or equal to 10 μm.

[0080] Thus, according to this second example, at least 99% of the particles have a volume mean diameter (called Dv99) less than or equal to 40 micrometers.

[0081] According to a third example, the proportion is greater than or equal to 75% and the threshold diameter is less than or equal to 25 μm, preferably less than or equal to 15 μm, even more preferably less than or equal to 5 μm.

[0082] Advantageously, the threshold diameter is less than or equal to 3 μm.

[0083] Thus, according to this third example, at least 75% of the particles have a volume mean diameter less than or equal to 25 micrometers (called Dv75).

[0084] According to a fourth example, the proportion is greater than or equal to 50% and the threshold diameter is less than or equal to 5 μm, even more preferably less than or equal to 3 μm.

[0085] Advantageously, the threshold diameter is less than or equal to 1 μm.

[0086] Thus, according to this fourth example, at least 50% of the particles have a mean volumetric volume (called Dv50) less than or equal to 5 micrometers.

[0087] According to a fifth embodiment, all particles have a volume average diameter of less than or equal to 40 μm, preferably less than or equal to 30 μm, and even more preferably less than or equal to 20 μm. Advantageously, the volume average diameter of such a proportion of 100% is less than or equal to 15 μm.

[0088] In each of the described examples, at least 50% of the particles of the second composition C2 forming the interface layer 20 have a volume average diameter less than or equal to 10 μm.

[0089] The diameter of the particles is obtained by the selection of the binding material ML2, the conductive additive AC2 and the solvent S2, by the mass of these various elements, by the implementation methods including mixing and grinding. The mixing technique consists of pre-dispersing the conductive additive in the solubilized binding material, the conductive additive at this stage being in agglomerates (large particles with a diameter greater than 50 μm). The grinding technique consists of breaking the agglomerates to obtain the volume average diameter of the particles, as previously disclosed.

[0090] This corresponds to the fact that the expression "the composition is formed by particles, at least 50% of the particles having a volume average diameter of 10 micrometers or less" means that the average diameter is measured for the particles in the composition, and excludes the measurement of the diameter of the components in the form of particles before insertion of the composition, when the formation of the composition changes the size of the particles.

[0091] Thus, in such a context, the second composition C2 may be formed from the particles, or may be written in an equivalent manner as being a composition that includes the particles.

[0092] In other words, the volume average diameter measurement here is a particle size analysis of the carbonized ink, i.e., the dispersion of carbon within the polymer matrix.

[0093] The choice of the second bonding material ML2 can vary considerably, as long as it is inert to the other materials of the second composition C2. The second bonding material ML2 comprises one or several polymers selected from thermoplastic polymers, thermosetting polymers, elastomers and mixtures thereof.

[0094] Examples of thermoplastic polymers include, but are not limited to, polymers derived from the polymerization of aliphatic or alicyclic vinyl monomers, such as polyolefins (including polyethylene or polypropylene), polymers derived from the polymerization of aromatic vinyl monomers, such as polystyrene, polymers derived from the polymerization of acrylic monomers and / or methacrylates, polyamides, polyether ketones, polyimides, polyvinyl alcohol, fluorinated polymers, polyacrylonitrile.

[0095] Examples of thermosetting polymers include, but are not limited to, thermosetting resins (such as epoxide resins or polyester resins) optionally mixed with polyurethanes or such polyethers, or vice versa.

[0096] Examples of elastomeric polymers include, but are not limited to, natural rubber, synthetic rubber, styrene-butadiene copolymers (also abbreviated as "SBR"), ethylene-propylene copolymers (also abbreviated as "EPM"), and silicones.

[0097] The second bonding material ML2 may be a mixture of thermoplastic, thermosetting and / or elastomeric polymers.

[0098] Other suitable second binding material(s) ML2 include crosslinked polymers such as those made from a polymer having carboxyl groups and a crosslinking agent.

[0099] The second conductive additive AC2 includes one or several types of conductive elements for improving electronic conductivity.

[0100] Examples of conductive elements include, but are not limited to, conductive carbon, graphite, graphene, carbon nanotubes, activated carbon fibers, non-activated carbon nanofibers, metal flakes, metal powders, metal fibers, and conductive polymers.

[0101] The second solvent S2 is selected from among water, ethanol, butanol, isopropyl alcohol (also called isopropanol), glycol ethers and mixtures thereof.

[0102] The operation of the battery 10 follows that of prior art electrochemical batteries.

[0103] To evaluate the performance of the interfacial layer 20, the coverage of the current collector with the state of the art layer was compared visually with the state of the art interfacial layer 20.

[0104] In particular, a comparison is made between a commercial composition (DAG EB-012 from Henkel Inc.) and a second composition C2, in which 90% of the particles have a volume mean diameter (Dv90) of 5 μm and 99% of the particles have a volume mean diameter (Dv90) of 10 μm.

[0105] By comparison, a commercially available composition is determined to contain particles of which 90% have a threshold diameter of 49 μm, 99% have a threshold diameter of 85 μm, and 50% have a threshold diameter of 13 μm.

[0106] Figures 3 and 4 correspond to photographs obtained with a scanning electron microscope at a magnification of 1000 times.

[0107] In Figure 3, the interface layer resulting from the coating of the commercial composition shows holes even at a thickness of 5 μm, as can be observed in Figure 3. The thickness cannot be reduced without producing areas with severely under-covered coverage.

[0108] Even with a thickness of 5 μm, the coverage does not visually reach the coverage observed with the 1 μm thick interface layer 20 obtained from the second composition C2 observed in FIG.

[0109] The current collector in FIG. 4 appears to be completely covered by the interfacial layer 20, whereas in FIG. 3 the current collector is visible, especially at the holes 30.

[0110] These tests correspond to an unexpected observation by applicants that good coverage of the current collector is obtained when the particle size of the particles forming the interfacial layer 20 is controlled.

[0111] Such high quality coverage allows for protection of the current collector, and thus the interfacial layer acts as a physical barrier to the access of corrosion-causing ions.

[0112] Further testing has shown that this coverage provides excellent corrosion resistance even at high potentials.

[0113] In particular, oxidation of the current collector occurs from a potential of 3.7 V in the interface layer obtained from the commercial composition (3.7 V corresponds to the oxidation potential of aluminum, and the holes in the interface layer are direct access in the electrolyte for aluminum to oxidize), whereas, as mentioned above, oxidation of the current collector does not occur until 4.2 V in the interface layer 20.

[0114] This indicates that the interface layer 20 is a layer that prevents oxidation of the current collector even when the operating potential of the device that stores electrical energy is equal to or higher than the oxidation potential of the material of the current collector.

[0115] Thus, a current collector forming an assembly has been disclosed which makes it possible to obtain a storage battery having a better performance level whilst being able to supply higher voltages than those supplied by the prior art, in particular voltages higher than 3.5 volts.

[0116] The current collectors can also be used in other electrical energy storage devices, such as supercapacitors. The present invention can be embodied in the following manner. (Appendix 1) A current collector (22) for a device for storing electrical energy, the current collector (22) being coated with an interface layer (20), the interface layer (20) being formed by coating a composition (C2) on the current collector (22), the composition (C2) being formed by particles, at least 50% of the particles having a volume average diameter of 10 micrometers or less. (Appendix 2) 2. The current collector of claim 1, wherein the interfacial layer (20) is a layer that acts as a physical barrier to the access of corrosion-causing ions. (Appendix 3) The current collector according to claim 1 or 2, wherein the interface layer is a layer that prevents oxidation of the current collector (22) even when an operating potential of a device for storing electrical energy is equal to or higher than the oxidation potential of the material of the current collector (22). (Appendix 4) 4. The current collector according to any one of claims 1 to 3, wherein the current collector (22) is adapted for a device for storing electrical energy, comprising an electrolyte comprising an ionic salt selected from lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI), lithium bis(fluorosulfonyl)imide salt (LiFSI) salt, lithium trifluoromethanesulfonate salt (LiTF), lithium tetrafluoroborate salt (LiBF4), lithium bis(oxalato)borate salt (LiBOB), lithium difluoro(oxalato)borate salt (LiDFOB), and mixtures thereof. (Appendix 5) 5. The current collector according to claim 4, wherein the ionic salt is lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI). (Appendix 6) 6. The current collector according to any one of claims 1 to 5, wherein at least 90% of the particles have a volume average diameter of 15 micrometers or less. (Appendix 7) 7. The current collector according to any one of claims 1 to 6, wherein at least 99% of the particles have a diameter of 10 micrometers or less. (Appendix 8) The current collector according to any one of claims 1 to 7, wherein the composition (C2) comprises a conductive material (MC) and a binding material (ML). (Appendix 9) 9. The current collector according to any one of claims 1 to 8, wherein the composition (C2) consists of a conductive additive (AC2), a solvent (S2) and a binding material (ML2). (Appendix 10) 10. The current collector of claim 8 or 9, wherein the conductive material (MC) comprises at least one element selected from the list consisting of: -carbon, Carbon black, -Graphite, -Graphene, -carbon nanotubes, Activated carbon fiber, and -Non-activated carbon nanofiber. (Appendix 11) 11. The current collector according to any one of claims 1 to 10, wherein the interface layer (20) has a thickness of 1 micrometer or more. (Appendix 12) 11. The current collector according to any one of claims 1 to 10, wherein the interface layer (20) has a thickness of 4 micrometers or less. (Appendix 13) 11. The current collector according to any one of claims 1 to 10, wherein the interface layer (20) has a thickness of 2 micrometers or less. (Appendix 14) An assembly forming an anode or a cathode, comprising: -electrodes, and - A current collector (20) according to any one of Appendices 1 to 13. The assembly containing: (Appendix 15) 15. An electrical energy storage device, electrochemical accumulator or supercapacitor comprising the assembly of claim 14.

Claims

1. A current collector (22) for a device for storing electrical energy, the current collector (22) being coated with an interface layer (20), the interface layer (20) being formed by coating a composition (C2) on the current collector (22), the composition (C2) comprising a conductive additive, a solvent and a binder material, the composition (C2) being formed by particles, at least 50% of the particles having a volume average diameter of 10 micrometers or less, the volume average diameter being measured for the particles in composition (C2) using a particle size distribution meter by static light and processing data obtained by the particle size distribution meter to calculate a particle size distribution based on a spherical model of equivalent volume.

2. 2. The current collector of claim 1, wherein the interfacial layer (20) is a layer that acts as a physical barrier to the access of corrosion-causing ions.

3. 3. The current collector according to claim 1 or 2, wherein the interfacial layer is a layer that prevents oxidation of the current collector (22) even when the operating potential of a device for storing electrical energy is equal to or higher than the oxidation potential of the material of the current collector (22).

4. 4. The current collector of claim 1, wherein the current collector (22) is adapted for a device for storing electrical energy comprising an electrolyte comprising an ionic salt selected from lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI) salt, lithium trifluoromethane-sulfonate (LiTF), lithium tetrafluoroborate (LiBF4), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), and mixtures thereof.

5. 5. The current collector of claim 4, wherein the ionic salt is lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI).

6. The current collector of any one of claims 1 to 5, wherein at least 90% of the particles have a volume average diameter of 15 micrometers or less.

7. The current collector of any one of claims 1 to 6, wherein at least 99% of the particles have a diameter of 10 micrometers or less.

8. 8. The current collector of claim 1, wherein the conductive additive comprises at least one member selected from the list consisting of: -carbon, - carbon black, - graphite, -graphene, - carbon nanotubes, - activated carbon fibres, and - Non-activated carbon nanofibers.

9. The current collector of any one of claims 1 to 8, wherein the interfacial layer (20) has a thickness of 1 micrometer or greater.

10. The current collector of any one of claims 1 to 8, wherein the interfacial layer (20) has a thickness of 4 micrometers or less.

11. The current collector of any one of claims 1 to 8, wherein the interfacial layer (20) has a thickness of 2 micrometers or less.

12. An assembly forming an anode or a cathode, comprising: - electrodes, and - Current collector (20) according to any one of claims 1 to 11 The assembly containing:

13. 13. An electrical energy storage device, electrochemical accumulator or supercapacitor comprising an assembly according to claim 12.

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