Dispersion electrolyte and chemical bath for particle-containing nickel and nickel alloy layers

Abstract

The invention relates to, among others, a dispersion electrolyte for galvanically depositing particle-containing nickel or nickel alloy layers. The dispersion electrolyte comprises 2 to 200 g / L of nickel ions, in total 1 to 200 g / L of at least one type of particle, selected from inorganic piezoelectric particles, electrically conductive ceramic particles, and combinations thereof, an anionic and / or non-ionic dispersant, and water. In the case of a nickel alloy, the dispersion electrolyte contains ions of at least one other metal, selected from transition metals, noble metals, and combinations thereof, in a total concentration of up to 40 g / L and / or at least one non-metal compound, selected from phosphor compounds, sulfur compounds, selenium compounds, tellurium compounds, carbon compounds, and combinations thereof, in a total concentration of up to 50 g / L. The pH value equals 2.0 to 7.0. By virtue of the dispersion electrolyte, a particle-containing nickel or nickel alloy layer can be galvanically deposited onto a metal or metallized substrate.

Description

[0001] 1 264 470 n / n27 Dispersion electrolyte and chemical bath for particle-containing nickel and nickel alloy layers Description Technical field of the invention The present invention relates to a dispersion electrolyte for the galvanic deposition of particle-containing nickel or nickel alloy layers, a bath for the electroless deposition of particle-containing nickel or nickel alloy layers, methods for the galvanic or electroless coating of a substrate with a particle-containing nickel or nickel alloy layer, a coated substrate with a particle-containing nickel or nickel alloy layer, and an electrochemical cell comprising the coated substrate. Technical background For many electronic applications, it is desirable to partially or completely replace precious metals with less expensive non-precious metals. In addition to good electrical properties, resistance to corrosion is also desirable in order toto obtain long-lasting and thus sustainable electronic components, such as a contact or an electrode. However, many non-precious metals and their alloys exhibit insufficient corrosion resistance, for example, against aqueous alkaline media. There is therefore a need to provide electronic components with a corrosion-resistant protective layer. For applications in aqueous alkaline media, coatings made of nickel or a nickel alloy can be used, for example, which can be deposited galvanically from an electrolyte or electrolessly, i.e., chemically, from a bath. Such nickel and alloy layers can therefore serve as a cost-effective replacement for precious metals. However, compared to precious metals, they often have poorer electrical properties. This can manifest itself, for example, in increased contact resistance compared to other metals. Furthermore,Electrochemical reactions in aqueous media, particularly in aqueous alkaline media, overvoltages are observed, which are often caused by the kinetic inhibition of a reaction. It would therefore be desirable to develop coatings that ensure good corrosion protection while simultaneously improving electrical properties, particularly reducing overvoltages in aqueous alkaline media. Furthermore, compositions and processes are needed with which these coatings can be produced economically. Summary of the Invention: One object of the present invention is therefore to provide an electrolyte for the electrodeposition and a bath for the electroless deposition of nickel or nickel alloy layers that are corrosion-resistant in the alkaline range and that are capable of reducing overvoltages for electrochemical reactions in aqueous alkaline media. Further objectsconsist in providing methods for coating substrates with such a nickel or nickel alloy layer, which use the electrolyte or the bath for electroless plating, the coated substrate, and applications thereof. These objects are achieved by the dispersion electrolyte for the electrodeposition of particle-containing nickel or nickel alloy layers, the bath for the electroless plating of particle-containing nickel or nickel alloy layers, the method for the electrodeposition or electroless coating of a substrate with a particle-containing nickel or nickel alloy layer, which use the dispersion electrolyte or the bath, the coated substrate, and an electrochemical cell comprising the coated substrate, according to the independent claims. Optional and preferred embodiments are specified below and in the dependent claims. Brief description of the figures. Shown are: Fig. 1 AScanning electron microscope image of the particle-containing layer of Example 1 Fig. 2 A scanning electron microscope image of the particle-containing layer of Example 2 Fig. 3 A scanning electron microscope image of the particle-containing layer of Example 3 Fig. 4 A scanning electron microscope image of the layer of Comparative Example 1 Fig. 5 A) Light microscope image and B) Scanning electron microscope image of the cross-section of Example 2 Fig. 6 A) Light microscope image and B) Scanning electron microscope image of the cross-section of Example 3 Fig. 7 A light microscope image of the cross-section of Comparative Example 1 Fig. 8 A scanning electron microscope image of the particle-containing layer of Example 4 Fig. 9 A scanning electron microscope image of the particle-containing layer of Example 5 Fig. 10 A scanning electron microscope image of the particle-containing layer of Example 6 Fig. 11 A) Light microscope image and B) Scanning electron microscope image of the Cross section of example 5Fig. 12 A) Light microscope image and B) scanning electron microscope image of the cross-section of Example 6 Fig. 13 A scanning electron microscope image of the particle-containing layer of Example 7 Fig. 14 A scanning electron microscope image of the particle-containing layer of Example 8 Fig. 15 A scanning electron microscope image of the particle-containing layer of Example 9 Fig. 16 A) Light microscope image and B) scanning electron microscope image of the cross-section of Example 8 Fig. 17 A) Light microscope image and B) scanning electron microscope image of the cross-section of Example 9 Detailed description of the invention The present invention provides a dispersion electrolyte for the electrodeposition of particle-containing nickel layers or particle-containing nickel alloy layers. The dispersion electrolyte comprises: - nickel ions in a concentration of 2 to 200 g / L; - at least one type of particles selected from inorganic piezoelectric particles,electrically conductive ceramic particles and combinations thereof, in a total concentration of 1 to 200 g / L; - at least one dispersant selected from anionic dispersants, non-ionic dispersants and combinations thereof; - optionally ions of at least one further metal selected from transition metals, noble metals and combinations thereof, in a total concentration of up to 40 g / L; - optionally at least one non-metal compound different from the dispersant and selected from phosphorus compounds, sulfur compounds, selenium compounds, tellurium compounds, carbon compounds and combinations thereof, in a total concentration of up to 50 g / L; and - water; The dispersion electrolyte has a pH of 2.0 to 7.0. The dispersion electrolyte is also referred to below as "electrolyte" for short. The inventors have surprisingly found that with the inventiveDispersion electrolytes make it possible to electrodeposit the uncharged particles together with a nickel layer or a nickel alloy layer, so that a particle-containing nickel or nickel alloy layer is formed. The deposited nickel or nickel alloy layer therefore contains, in addition to nickel or nickel alloy, particles of one or more inorganic piezoelectric materials and / or one or more electrically conductive ceramic materials. The deposited nickel alloy typically has a high nickel content of at least 65 wt.%, preferably at least 75 wt.%, more preferably at least 85 wt.%, even more preferably at least 90 wt.%, based on the alloy. The particles are not counted as part of the nickel alloy. A nickel alloy is electrodeposited when, in addition to nickel ions, ions of another metal, selected from transition and noble metals, which are electrodeposited together with nickeldeposited, and / or non-metal compounds that can be decomposed during electrodeposition and serve as precursor compounds for the incorporation of the corresponding non-metal atoms (P, S, Se, Te, and / or C) into the alloy, are present in the dispersion electrolyte. The other metals are different from nickel. The non-metal compounds are different from the dispersant. Furthermore, it was surprisingly found that with the particles made of an inorganic piezoelectric or electrically conductive ceramic material, an overpotential for electrochemical reactions at the interface in aqueous media, especially in aqueous alkaline media, can be reduced compared to corresponding nickel or nickel alloy layers without the particles. Due to the lower overpotential, less current is required for the same electrochemical reaction, thus improving the economic efficiency of the reaction. The electrolyteenables the particle-containing nickel or nickel alloy layer to be galvanically deposited on a metallic or metallized substrate. The process described below can be used for this purpose, which enables deposition over a wide temperature and current density range. During deposition, the particles are at least partially arranged on the surface of the particle-containing nickel or nickel alloy layer, so that they form part of the surface. The particle-containing nickel or nickel alloy layer is typically produced as a final layer, i.e., as the outermost layer, for example, as a single layer or part of a layer system, on a substrate. Furthermore, it was surprisingly found that the particle-containing nickel or nickel alloy layer, despite the particles, which are essentially foreign bodies in the nickel or nickel alloy layer, exhibits good corrosion resistance in weakly acidic and, in particular, alkaline conditions.which is comparable to the corrosion resistance of a corresponding nickel or nickel alloy layer without particles. The particle-containing nickel or nickel alloy layer is thus suitable as a protective layer against corrosion, particularly in the alkaline range. The dispersion electrolyte according to the invention thus enables the formation of layers that offer good protection against corrosion and reduce overvoltage for electrochemical reactions in aqueous media, so that these advantageous properties can be realized simultaneously in one layer. The particle-containing nickel or nickel alloy layer can therefore advantageously be used as a protective layer, in particular as the outermost layer on a component, in particular an electronic component, for example a contact or an electrode. The dispersion electrolyte according to the invention has at least one type of particle selected from inorganic piezoelectricParticles, electrically conductive ceramic particles, and combinations thereof. The particles can therefore consist of one or more types of inorganic piezoelectric particles and / or one or more types of electrically conductive ceramic particles. The particles can be made of an inorganic piezoelectric material, which can be monocrystalline or polycrystalline. A piezoelectric effect can occur in non-centrosymmetric point groups (crystal groups). The unit cell of the material therefore has no inversion center. Consequently, for example, cubic point groups with an inversion center do not exhibit piezoelectricity. If piezoelectric and non-piezoelectric modifications exist in inorganic materials, only the piezoelectric modifications are counted as particles. For example, barium titanate (BaTiO3) can exist in a perovskite structure and in a cubic modification thereof. SinceIf the cubic modification is not piezoelectric, it is not considered a particle. Another example is boron nitride (BN). Since hexagonal BN is piezoelectric, it can be used as a particle according to the invention. Cubic boron nitride is not piezoelectric and is therefore not considered a particle. The particles can also be made of an electrically conductive ceramic material. Non-ceramic electrically conductive particles, such as metal particles, are not considered particles. The inorganic piezoelectric particles and the electrically conductive ceramic particles are not limited according to the invention. Materials doped with foreign atoms can also be used as inorganic piezoelectric particles. The particles can be made of, for example, BN (hexagonal), AlN, ZnO, GaPO4, M1 2y MA 1-y [MB x Ti 1−x ]O3, M1 2y MA 1-y [MC x Zr 1−x ]O3, M12y MA 1-y [MD x Mn 1−x ]O3, M1 2y MA 1-y [ME x Hf 1−x ]O3, M1[MF x Nb 1−x ]O3, M1[MG x V 1−x ]O3, M1[MH x Ta 1−x ]O3, TiN, TiC, TiB2, Ti2CN, B4C, WC and combinations thereof. The following applies to the general formulas: M1 is each independently at least one element selected from Li, Na and K, preferably Li; MA is each independently at least one element selected from Ca, Sr, Ba, Pb and La; MB is each independently selected from Zr, Hf, Mn, Mg 1 / 3 Nb 2 / 3 , Mg 1 / 3 V 2 / 3 , Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ; MC is selected from Hf, Mn, Mg 1 / 3 Nb 2 / 3 , Mg 1 / 3 V 2 / 3 , Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ; MD is selected from Hf, Mg 1 / 3 Nb 2 / 3 , Mg 1 / 3 V 2 / 3 , Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3Ta 2 / 3 ; ME is selected from Mg 1 / 3 Nb 2 / 3 , Mg 1 / 3 V 2 / 3 , Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ; MF is selected from V, Ta and Mn; MG is selected from Ta and Mn; MH is Mn; x satisfies 0 ≤ x ≤ 1; and y satisfies 0 ≤ y ≤ 1. The particles are in particular made of BN (hexagonal), AlN, ZnO, GaPO4, Li 2y MA 1-y [MB x Ti 1−x ]O3, Li 2y MA 1-y [MC x Zr 1−x ]O3, Li 2y MA 1-y [MD x Mn 1−x ]O3, LiNbO3, LiVO3, LiMnO3, LiTaO3, TiN, TiC, TiB2, Ti2CN, B4C, WC, and combinations thereof. In the general formulas, the following applies: MA is independently at least one element selected from Ca, Sr, Ba, Pb, and La; MB is selected from Zr, Mn, and Mg. 1 / 3 Nb 2 / 3 ; MC is selected from Mn and Mg 1 / 3 Nb 2 / 3 ; MD is Mg 1 / 3 Nb 2 / 3; x each independently satisfies 0 ≤ x ≤ 1; and y each independently satisfies 0 ≤ y ≤ 1. Of the above-mentioned materials, TiN, TiC, TiB2, Ti2CN, B4C and WC are electrically conductive ceramic materials, and the rest are inorganic piezoelectric materials. According to a preferred embodiment, the particles are selected from inorganic piezoelectric particles. According to another preferred embodiment, the inorganic piezoelectric particles are selected from BN (hexagonal), AlN, ZnO, GaPO4, Li2[Zr x Ti 1−x ]O3, Li 2y MA 1-y [Zr x Ti 1−x ]O3, MA[Zr x Ti 1−x ]O3, Pb[Zr x Ti 1−x]O3, LaMnO3 and LiNbO3 and combinations thereof. The following applies to the general formulas: MA is in each case independently at least one element selected from Ca, Sr and Ba; x in each case independently satisfies 0 ≤ x ≤ 1; and y in each case independently satisfies 0 < y < 1. The particles are further preferably made of BN (hexagonal), AlN, BaTiO3, Li2ZrO3, Li2TiO3, CaTiO3, ZnO, LaMnO3, Pb[Zr x Ti 1−x]O3 (where x is in the range of 0 ≤ x ≤ 1), LiNbO3, GaPO4, and combinations thereof, and particularly preferably selected from BN (hexagonal), BaTiO3, CaTiO3, Li2ZrO3, and combinations thereof. The dispersion electrolyte contains the particles, selected from inorganic piezoelectric particles and / or electrically conductive ceramic particles, in a total concentration of 1 to 200 g / L. The dispersion electrolyte contains the particles in particular in a total concentration of 3 to 150 g / L, preferably 5 to 100 g / L, more preferably 8 to 80 g / L, even more preferably 15 to 60 g / L. At these concentrations, the dispersion electrolyte can be thoroughly mixed, and a suitable quantity of particles can be deposited with the nickel or nickel alloy layer to effectively reduce the overpotential for electrochemical reactions in aqueous media. As a rule, the particles should be smaller than the desired layer thickness of the particle-containing nickel or nickel alloy.Nickel alloy layer. The particle size can be adjusted, for example, using common grinding and / or sieving processes, which can be used to separate out particles that are too coarse or too fine. Suitable particles are often also commercially available. For particles with an aspect ratio of less than 3.0, the average particle diameter is typically in the range of 20 nm to 20 µm, preferably 0.1 to 10 µm, more preferably 0.5 to 8 µm. The aspect ratio indicates the ratio of the largest diameter to the smallest diameter of a particle. For spherical particles, the aspect ratio is therefore 1. The aspect ratio of the particles can be determined microscopically by measuring 20 randomly selected particles. Depending on the size of the particles, a light microscope or an electron microscope with a reference can be used.If the particles have an aspect ratio of 3.0 or more, the average particle length is typically 0.1 to 90 µm, preferably 0.5 to 50 µm, more preferably 0.8 to 20 µm. Particles with such an aspect ratio are generally flat or elongated, for example needle-shaped or flake-shaped. The length refers to the largest diameter of a particle. The particle size can be determined using laser diffraction according to ISO 13320:2020, e.g. using a HELOS spectrometer (Helium-Neon Laser Optical System). The mean particle size is given as the D50 value. In a deposited layer, the average particle size can be determined from a top view or on a cross-section using a microscope or electron microscope. At least 100 randomly selected particles are considered to determine the average particle size.In principle, all common water-soluble nickel salts can be used for the dispersion electrolyte. The electrolyte also contains the corresponding anions of the nickel salts. Suitable examples include nickel sulfamate, nickel sulfate, nickel chloride, nickel bromide, nickel acetate, and combinations thereof. Nickel sulfamate, nickel sulfate, nickel chloride, and combinations thereof are preferred. All modifications of the nickel salts, such as hydrates, can be used in the electrolyte. According to a preferred embodiment, the dispersion electrolyte contains sulfamate, sulfate, chloride, bromide, acetate, and combinations thereof as counteranions to the nickel ions, preferably sulfamate, sulfate, chloride, and combinations thereof. The concentration of nickel ions in the dispersion electrolyte is 2 to 200 g / L.The nickel ions are present in the electrolyte in a concentration of 5 to 180 g / L, preferably 10 to 160 g / L, more preferably 20 to 150 g / L, and even more preferably 40 to 140 g / L. The concentration refers to the nickel ions in the form of Ni. 2+At these concentrations, the electrolyte is storage-stable and can be operated economically with reasonable deposition rates. Typically, high particle concentrations are used in the electrolyte at high nickel ion concentrations. Typically, the weight ratio of nickel ions to particles is in the range of 20:1 to 1:3, preferably 10:1 to 1:2, more preferably 5:1 to 1:2. The layer deposited from the dispersion electrolyte is a particle-containing nickel layer or a particle-containing nickel alloy layer. It is preferably a particle-containing nickel layer.A dispersion electrolyte for a particle-containing nickel layer generally contains no ions of other metals—apart from any unavoidable impurities—selected from transition and / or precious metals that are electrodeposited together with nickel, or non-metal compounds that decompose during electrodeposition to form a nickel alloy and serve as precursor compounds for the incorporation of the corresponding non-metal atoms (P, S, Se, Te, and / or C) into the alloy. Such ions and / or non-metal compounds are present in the dispersion electrolyte if a particle-containing nickel alloy layer is to be deposited.If the dispersion electrolyte contains ions of at least one further metal selected from transition metals, noble metals, and combinations thereof, these are present in a total concentration of up to 40 g / L, preferably up to 30 g / L, more preferably up to 20 g / L, and even more preferably up to 10 g / L. In this embodiment, the weight ratio of nickel ions to the ions of the further metal in the electrolyte is typically 80:20 or more, preferably 85:15 or more, more preferably 90:10 or more, even more preferably 95:5 or more. If the dispersion electrolyte contains at least one non-metal compound selected from phosphorus compounds, sulfur compounds, selenium compounds, tellurium compounds and combinations thereof, these are present in a total concentration of up to 50 g / L, preferably up to 30 g / L, more preferably up to 15 g / L and even more preferably up to 5 g / L.The weight ratio of nickel ions to the total of the phosphorus atoms, sulfur atoms, selenium atoms, and tellurium atoms in the at least one non-metal compound is typically 85:15 or more, preferably 90:10 or more, more preferably 95:5 or more. The non-metal compounds thus serve as precursor compounds for P, S, Se, Te, or C atoms in a nickel alloy. The additional metal comprises, in particular, at least one element selected from Fe, Co, Mo, Cr, Cu, Zn, Sn, Bi, Sb, and combinations thereof, and preferably consists thereof. According to a preferred embodiment, the additional metal comprises or consists of Fe, Co, Mo, or Cu. This means that according to this embodiment, the electrolyte contains ions of one or more of these additional metals, which can be electrodeposited together with nickel. The additional metals can be added in the form of soluble salts.The non-metal compound can in particular comprise, and preferably be selected from, at least one compound selected from hypophosphites, a urea, a thiourea, a thiocyanate, selenourea, lithium bis(trifluoromethanesulfonyl)imide, dimethyl telluride, a xanthate, a carbamate, a ketone (for example, benzalacetone), an aromatic aldehyde (for example, naphthaldehyde), Turkey red oil, and combinations thereof. During electrodeposition, the non-metal compounds can be decomposed, and P, S, Se, Te, or C atoms can be incorporated into the nickel alloy, respectively. The non-metal compound preferably comprises, or consists of, one or more compounds selected from thiourea, a thiocyanate, selenourea, lithium bis(trifluoromethanesulfonyl)imide, a xanthate, a carbamate, naphthaldehyde, benzalacetone (4-phenylbutenone), and Turkey red oil.According to this embodiment, S, Se, and / or C atoms are incorporated into the nickel alloy. S and / or Se atoms are particularly preferred. The non-metal compound then comprises or consists of at least one non-metal compound selected from thiourea, a thiocyanate, selenourea, lithium bis(trifluoromethanesulfonyl)imide, and combinations thereof. In principle, in addition to the particles selected from inorganic piezoelectric particles, electrically conductive ceramic particles, and combinations thereof, the dispersion electrolyte can also contain further particles in order to modify the properties of the particle-containing nickel or nickel alloy layer. According to a further embodiment, the dispersion electrolyte comprises, as further particles, electrically conductive particles made of a carbon material, preferably graphite particles, in a total concentration of 1 to 100 g / L, preferably 2 to 50 g / L, more preferably 5 to 40 g / L.These particles can be used, for example, to improve the tribological properties of the particle-containing nickel or nickel alloy layer or to reduce the contact resistance with metals. According to a further embodiment, the dispersion electrolyte contains no electrically conductive particles made of a carbon material and preferably no particles other than the particles selected from inorganic piezoelectric particles, electrically conductive ceramic particles, and combinations thereof. The additional particles preferably have a particle size according to the embodiments described above for the particles.If the dispersion electrolyte contains further particles in addition to the particles selected from inorganic piezoelectric particles, electrically conductive ceramic particles, and combinations thereof, the total amount of particles, i.e., the total solids content, in the dispersion electrolyte typically does not exceed 200 g / L, preferably not 150 g / L, and more preferably not 120 g / L. Thus, good miscibility of the dispersion electrolyte and excessive agglomeration of particles in the deposited layer can be avoided. To achieve efficient dispersion of the particles and, if present, of the other particles in the electrolyte and to avoid significant clumping of the particles in the nickel or nickel alloy layer, the dispersion electrolyte according to the invention contains at least one anionic and / or at least one nonionic dispersant.Typically, an anionic dispersant contains sulfate groups (OSO3-), sulfonate groups (SO3-), carboxylate groups (CO2-), or carboxy groups (CO2H), which can then be present as anions in aqueous solution. Counterions are usually H. + , alkali metal ions, preferably K + and / or Na + , and / or ammonium ions (NH4 + ) because they result in good water solubility, can increase conductivity, and do not negatively influence the electrodeposition. The electrolyte therefore also contains counterions of the anionic dispersant, preferably Na + and / or K +Sulfate groups and sulfonate groups are dissociated, i.e., non-protonated, at the pH of the dispersion electrolyte. Carboxy groups and carboxylate groups, however, can exist in equilibrium with each other. The anionic and / or non-ionic dispersant is typically used in the dispersion electrolyte at a total concentration of 0.1 to 100 g / L. In particular, it is used in the electrolyte at a total concentration of 0.5 to 50 g / L, preferably 0.6 to 20 g / L. The appropriate amount of dispersant can vary depending on the type of dispersant. In general, the more dispersant used, the better the dispersion of the particles.In the dispersion electrolyte, the weight ratio of the dispersant, selected from anionic dispersants, nonionic dispersants, and combinations thereof, to the total amount of particles (i.e., the solids content), i.e., the particles and, if present, the optional additional particles, is in particular in the range from 25:1 to 1:80, preferably 5:1 to 1:60, more preferably 1:5 to 1:50. Examples of nonionic dispersants are polyalkylene glycol ethers, in particular polyethylene glycol ethers, alkyl polyglucosides, or alkyl polyalkylene glycol ethers, and combinations thereof. According to a preferred embodiment, the dispersant comprises or consists of at least one anionic dispersant. Preferably, at least 60% by weight or more, more preferably at least 80% by weight or more, of the dispersant is one or more anionic dispersants.According to a further preferred embodiment, the dispersant comprises or consists of at least one anionic dispersant selected from sulfate compounds having an alkyl group, an aralkyl group or an aromatic group each having up to 30 carbon atoms, sulfonate compounds having an alkyl group, an aralkyl group or an aromatic group each having up to 30 carbon atoms, and carboxy- or carboxylate-group-containing polymers.More preferably, the anionic dispersant comprises at least one dispersant selected from sulfate compounds having an alkyl group with 6 to 24 carbon atoms, preferably with 10 to 20 carbon atoms, sulfate compounds having an aralkyl group with 6 to 24 carbon atoms, preferably with 10 to 20 carbon atoms, sulfonate compounds having an aromatic group each with 6 to 24 carbon atoms, preferably 6 to 14 carbon atoms, and combinations thereof. It may also consist of these.According to a particularly preferred embodiment, the anionic dispersant comprises at least one first anionic dispersant selected from sulfate compounds having an alkyl group with 6 to 24 carbon atoms, preferably with 10 to 20 carbon atoms, sulfate compounds having an aralkyl group with 6 to 24 carbon atoms, preferably with 10 to 20 carbon atoms, and combinations thereof, and at least one second anionic dispersant selected from sulfonate compounds having an aromatic group with 6 to 24 carbon atoms, preferably 6 to 14 carbon atoms. Preferably, the anionic dispersant consists of at least one first and at least one second anionic dispersant. These are used in particular in a weight ratio of first anionic dispersant to second anionic dispersant of 1:10 to 10:1, preferably 1:8 to 3:1, more preferably 1:3 to 2:1.The combination of the first and second dispersant is advantageous for effective dispersion of the particles and wetting of the surface of the substrate to be coated, which can improve deposition. The sulfate compounds containing an alkyl group are preferably selected from alkyl sulfates, alkyl polyether sulfates, alkyl aryl polyether sulfates, and combinations thereof. The alkyl group having 6 to 24 carbon atoms, preferably 10 to 20 carbon atoms, originates in particular from a fatty alcohol. Polyether groups are preferably polyethylene glycol groups. The sulfonate compounds containing an aromatic group having 6 to 24 carbon atoms, preferably 6 to 14 carbon atoms, are preferably selected from arylsulfonates and polymers containing aromatic sulfonate groups. Particularly preferred arylsulfonates are benzenesulfonic acid, phenolsulfonic acid, and naphthalenesulfonic acid, especially naphthalenesulfonic acid, and salts thereof.In polymers with aromatic sulfonate groups, the underlying aromatic groups preferably each have 6 to 14 carbon atoms and are derived in particular from benzenesulfonic acid, phenolsulfonic acid, and naphthalenesulfonic acid, and salts thereof. Such polymers are, for example, polycondensates of aromatic sulfonate compounds, such as benzenesulfonic acid, phenolsulfonic acid, and naphthalenesulfonic acid, or salts thereof, with formaldehyde, in particular naphthalenesulfonic acid-formaldehyde polycondensates and salts thereof, for example, tamole. ®from BASF SE. According to a further preferred embodiment, the dispersion electrolyte further comprises a buffer compound having a pKa value between 2.5 and 10 and is preferably selected from boric acid, acetic acid, and combinations thereof, particularly preferably boric acid. The buffer compound is used in particular in a concentration of 1 to 80 g / L, preferably 10 to 70 g / L, more preferably 20 to 60 g / L. The pH of the dispersion electrolyte is in the range from 2.0 to 7.0, preferably 2.5 to 6.0, more preferably 3.0 to 5.0, for example 4. The pH can result directly from the constituents of the dispersion electrolyte or can be adjusted by adding acids or bases, in particular hydrochloric acid, sulfuric acid, sulfamic acid, sodium hydroxide, ammonia, potassium hydroxide, or an aqueous solution thereof.Furthermore, the dispersion electrolyte can contain conventional additives, such as those known from conventional electrolytes for the electrodeposition of nickel layers or nickel alloy layers. For example, conventional conducting salts can be added to increase the conductivity of the electrolyte. The conducting salt is selected, for example, from sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, ammonium chloride, sodium acetate, potassium acetate, ammonium acetate, ammonium fluoride, ammonium bifluoride, sodium fluoride, and potassium fluoride, and combinations thereof, preferably from potassium chloride, potassium sulfate, sodium chloride, and sodium sulfate, and combinations thereof. Furthermore, complexing agents, for example, can be added to the dispersion electrolyte to stabilize ions of the other metal in the electrolyte and increase the deposition rate of the other metals.In principle, all complexing agents known to those skilled in the art and used for electrolytes can be used as complexing agents. The complexing agent is preferably a chelating, water-soluble, organic compound having at least three functional groups selected from amino groups, carboxyl groups, and carboxylate groups. Of the functional groups, at least two are preferably amino groups. The amino groups are selected from primary, secondary, and tertiary amino groups. More preferably, the complexing agent contains one or more secondary and / or tertiary amino groups. The functional groups intended for coordination are typically spaced apart by 2 or 3 carbon atoms, so that a stable chelate complex can form. Particularly preferably, the complexing agent is at least one selected from the group consisting of EDTA, DETA, DOTA, and DOTATOC. EDTA stands for ethylenediaminetetraacetic acid.DETA stands for diethylenetriamine. DOTA stands for 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid. DOTAATOC refers to a DOTA-derived complexing agent in which a DOTA molecule is linked to the N-terminus of an octapeptide (especially Phe-Cys-Tyr-Lys-Thr-Cys-Thr) via an amide bond. Other suitable complexing agents are hypophosphites, which can also lead to the incorporation of P atoms into a nickel alloy. The dispersion electrolyte can be formed by mixing or dissolving a nickel salt, the optional salts of the other metals, the optional non-metal compounds, and the other components, i.e., dispersant, the particles, water, and optionally a buffer compound, a conducting salt, and / or a complexing agent.The particles and, if present, the other particles can advantageously be added as a powdered solid without the need to disperse them separately or to treat the mixture with ultrasound for dispersion. When forming the electrolyte, stirring is preferably carried out and, if necessary, slightly heated to accelerate the dissolution or dispersion of the components. The pH can be adjusted as required, as described above. The dispersion electrolyte according to the invention can advantageously be produced on a large scale and is thus suitable for industrial applications. The electrolyte is storable, and any settled particles can be redispersed by stirring or the like. As a further aspect, the present invention relates to a process for electroplating a substrate with a particle-containing nickel or nickel alloy layer.The method comprises the electrodeposition of the particle-containing nickel layer or the particle-containing nickel alloy layer on a metallic or metallized substrate using the dispersion electrolyte according to at least one embodiment described herein. The method is carried out at temperatures in the range from 20 to 85°C, preferably 40 to 75°C, more preferably 50 to 70°C. By means of the method, a coated substrate with a particle-containing nickel layer or a particle-containing nickel alloy layer is obtainable, for which the advantages described above are obtained. In particular, it can be a coated substrate as described in more detail below. By means of the method, the particles are at least partially arranged on the surface of the particle-containing nickel or nickel alloy layer, such that they form part of the surface. The particle-containing nickel orA nickel alloy layer is typically applied as the final layer, i.e., the outermost layer, on the substrate. The process can be performed using all common devices for the electroplating of nickel or nickel alloy layers, for example, rack or drum electroplating. Typically, the electrolyte is thoroughly mixed during deposition, for example, stirred or circulated using a device. Stirring is preferred, for example, at 100 to 700 revolutions per minute (rpm). The metallic or metallized substrate serves as the cathode in the process. This can be, for example, a metallic component, such as an electronic component, such as a contact, a switch part, or an electrode. The metallic or metallized substrate can consist entirely or partially of one or more metals.Examples of metals include aluminum, silver, copper, nickel, precious metals such as palladium or platinum, steel, stainless steel, brass, and / or bronze. A metal layer that can be electroplated can also be used as a substrate, for example, a metallized plastic, in particular with a metal layer made of copper, nickel, silver, and / or precious metals such as palladium or platinum. The production of metallized plastics is described, for example, in DE 2126 781 C1 or WO 2020 / 225052 A1. The procedure can be analogous to the one described below for the electroless deposition of the particle-containing nickel or nickel alloy layer. The surface to be coated can be cleaned beforehand using conventional methods, for example, degreased.Before deposition of the particle-containing nickel or nickel alloy layer, the substrate can also be coated with one or more layers, for example of copper, nickel and / or silver, which can improve the adhesion of the particle-containing nickel or nickel alloy layer to the substrate. Nickel anodes, for example, can be used as the anode. This allows the content of nickel ions in the electrolyte to be easily controlled. Multiple anodes can also be used. Furthermore, the process allows for great flexibility in process control. In particular, it can be carried out over a wide current density range, for example with a current density of 0.1 to 10 A / dm. 2 , preferably 0.5 to 5 A / dm 2 , more preferably 1 to 4 A / dm 2, are deposited. In the process, the particle-containing nickel or nickel alloy layer can be deposited largely homogeneously, i.e. with a fairly even distribution of the particles. According to a further embodiment, the galvanic deposition can be carried out such that the particles (and / or the other particles, if present) have a gradient. For example, the particle concentration in the interior of the nickel or nickel alloy layer can be higher than on the outside. Preferably, the particle concentration is higher on the outside than in the interior of the nickel or nickel alloy layer. A gradient can be obtained, for example, by modifying the mixing, modifying the current density or changing the concentration of the particles during deposition. Greater mixing generally leads to increased incorporation of particles.A higher current density generally leads to increased deposition of nickel or nickel alloy. Furthermore, multiple electrolytes, which differ, for example, in particle concentration, nickel ion concentration, and / or the concentration of other metals or non-metallic compounds, can be used to electroplate the substrate in multiple stages. In principle, the process can be used to produce a particle-containing nickel or nickel alloy layer with any desired layer thickness. For example, the particle-containing nickel or nickel alloy layer can be formed with a layer thickness of up to 200 µm or up to 100 µm. Typically, the particle-containing nickel or nickel alloy layer is deposited with a thickness of 4 to 50 µm, preferably 5 to 30 µm, and more preferably 5 to 20 µm.The layer thickness is measured using X-ray fluorescence measurement in accordance with DIN EN ISO 3497 (2001-12), for example, with a Fischerscope X-ray fluorescence measuring device (XDAL) for layer thicknesses up to 20 µm. For layer thicknesses greater than 20 µm, the layer thickness is determined using a microscope at the cross-section of the layer. Typically, the deposit is carried out such that the thickness of the nickel or nickel alloy is greater than the particles. As a further aspect, the present invention provides a bath for the electroless deposition of particle-containing nickel or nickel alloy layers.The bath comprises: - nickel ions in a concentration of 2 to 200 g / L; - at least one type of particle selected from inorganic piezoelectric particles, electrically conductive ceramic particles, and combinations thereof, in a total concentration of 1 to 200 g / L; - at least one dispersant selected from anionic dispersants, non-ionic dispersants, and combinations thereof; - optionally, ions of another metal selected from transition metals, noble metals, and combinations thereof, in a total concentration of up to 50 g / L; - at least one reducing agent capable of reducing nickel ions to nickel and, if present, the ions of the other metal to the other metal; and - water. The bath has a pH of 3.0 to 12.0. The pH is preferably 5.0 to 9.0. The bath for electroless plating is also referred to below as “bath”.It refers to a composition from which the particle-containing nickel layer or the particle-containing nickel alloy layer can be deposited electrolessly by one or more chemical reactions. The other metal is different from nickel. It has surprisingly been found that, using the bath according to the invention, particle-containing nickel or nickel alloy layers can also be deposited electrolessly on a substrate. The substrate can be a metallic or metallized substrate, as described above. Furthermore, as described below, plastic substrates, which are optionally nucleated, can also be coated. Advantageously, a well-adhering, dense layer can be deposited, i.e. one which has hardly any or no pores. For the electrolessly deposited nickel or nickel alloy layer, the reactions described in connection with the dispersion electrolyte or the electrodeposited nickel or nickel alloy layer can be used in an analogous manner.The advantages described above can be obtained with a nickel alloy layer. The electrolessly deposited particle-containing nickel or nickel alloy layer contains the particles that are at least partially arranged on the surface, and nickel or a nickel alloy. Nickel and nickel alloys can contain unavoidable impurities. The nickel alloys typically have a nickel content of 70 wt.% or more, preferably 85 wt.% or more, and more preferably 90 wt.% or more. The electrolessly deposited nickel alloys can contain the additional metal, sulfur and / or phosphorus as further components. The concentration of the nickel ions in the bath is 2 to 200 g / L. The nickel ions are present in the bath in particular in a concentration of 5 to 180 g / L, preferably 10 to 160 g / L, more preferably 20 to 150 g / L, even more preferably 40 to 140 g / L.The ions of the optional further metal, selected from transition metals, noble metals, and combinations thereof, can be present in the bath at a concentration of up to 50 g / L, preferably up to 30 g / L, more preferably up to 10 g / L. The further metal is preferably selected from Fe, Pd, Re, Ru, Sn, Cu, Co, Bi, Au, and combinations thereof. Particularly preferably, it is one or more metals selected from Fe, Co, Sn, and Bi. The further metals can be electrolessly deposited together with nickel. The bath is preferably used for the electroless deposition of nickel layers and nickel alloys with P and / or S and—apart from any unavoidable impurities—contains no ions of the further metals. The bath further contains at least one reducing agent capable of reducing nickel ions to nickel and, if present, the ions of the further metal to the other metal.The reducing agent is used in a sufficient amount to reduce nickel and the optional other metals. It is used in particular at a concentration of 1 to 100 g / L, preferably 5 to 50 g / L. The reducing agent is not particularly limited, and any reducing agent known to the person skilled in the art that is suitable for the chemical deposition of nickel can be used. The reducing agent preferably comprises at least one reducing agent selected from a hypophosphite, dimethylaminoborane, NaBH4, a thiourea, a thiocyanate, and combinations thereof. It preferably consists of one or more of these reducing agents. The reducing agents can lead to the incorporation of non-metal atoms during electroless deposition. For example, the exemplary reducing agents mentioned above can result in the incorporation of P atoms, S atoms, or B atoms, respectively, so that a nickel alloy is obtained.A nickel alloy can therefore also be electrolessly deposited without ions of another metal. With regard to the preferred and optional embodiments of the bath, reference is made to the above statements regarding the particles, their concentrations, the optional additional particles, the dispersants and the formation of the dispersion electrolyte. The bath can be produced in a manner analogous to the dispersion electrolyte, in particular by mixing the components and, if appropriate, heating them to improve solubility. The pH can be adjusted as required, as described above. Optionally, a complexing agent can be used, as described above. As a further aspect, the present invention provides a method for the electroless coating of a substrate with a particle-containing nickel or nickel alloy layer. The method comprises the electroless deposition of the particle-containing nickel layer orthe particle-containing nickel alloy layer on a substrate using the bath for the electroless deposition of particle-containing nickel layers according to at least one embodiment described herein. The electroless deposition takes place at a temperature of 15 to 95°C, preferably 50 to 95°C, more preferably 70 to 90°C. The process for electroless deposition of the particle-containing nickel or nickel alloy layer makes it possible to obtain a coated substrate with a particle-containing nickel layer or a particle-containing nickel alloy layer, for which the advantages described above are obtained. It can be a coated substrate as described in more detail below. The particle-containing nickel or nickel alloy layer is formed, in particular, as the outermost layer. The particles lie at least partially on the surface of the particle-containing layer, thus forming part of the surface.The process can be carried out using all common devices for the electroless deposition of nickel or nickel alloy layers. Typically, the bath is thoroughly mixed during deposition, for example, by stirring or circulating it using a device. Stirring is preferred, for example, at 100 to 700 revolutions per minute. According to a preferred embodiment, the substrate is arranged with the surface to be coated facing upwards, which can facilitate the incorporation of the particles into the nickel or nickel alloy layer. The deposition rate of the particles can be controlled by mixing. During electroless deposition, no voltage is applied; instead, the nickel or nickel alloy layer is deposited through a chemical reaction. The metallic or metallized substrates described above can be used.Furthermore, plastic substrates with polar surfaces can be used directly, for example ABS or plastics functionalized by sulfonation or oxidation, in particular plastics functionalized by sulfonation. Plastics can be functionalized, for example, as described in DE 2126 781 C1 or WO 2020 / 225052 A1, in particular the examples of these publications. The polar or functionalized plastics are preferably nucleated before the electroless deposition of the nickel or nickel alloy layer, as described, for example, in DE 2126 781 C1 or WO 2020 / 225052 A1. During nucleation, metal nuclei, i.e. nuclei made of metal, are formed on the, in particular sulfonated, plastic surface. The metal is preferably selected from the group consisting of Pd, Ag, Au, Pt, Cu, Co, Ni, and Pd / Sn.Typically, either a solution of a metal colloid is used for nucleation, or the plastic surface, especially a sulfonated one, is first treated with a noble metal ion solution, and then the adsorbed noble metal ions are reduced to metal nuclei using a reducing agent. The use of such metal colloids is described, for example, in DE 19611 137 and US 4,520,046. The plastics are preferably selected from the group consisting of polyacrylester-styrene-acrylonitrile, polyacrylonitrile-butadiene-styrene, polyamide, polyarylamide, polyphthalamide, polyimide, polyetherimide, polyetheretherketone, polysulfone, polyethersulfone, polyphenylene sulfide, polyphenylene oxide, polyvinyl chloride, polyethylene, polypropylene, polystyrene, syndiotactic polystyrene, polyester, polyurethane, epoxy resins, and epoxy varnishes. If necessary, the surface to be coated can be cleaned beforehand using conventional methods, for example, degreased.Before the particle-containing nickel or nickel alloy layer is deposited, the substrate can be coated with one or more layers of copper, nickel, and / or silver. A gradient can be formed in the process for electroless deposition of the particle-containing nickel or nickel alloy layer. A gradient can be set, for example, by varying the particle concentration during deposition. A gradient is preferably set by using multiple baths with different nickel ion concentrations and / or different particle concentrations, with which the substrate is successively coated. Furthermore, particle-containing nickel or nickel alloy layers of any desired thickness can be formed, in particular according to the embodiments described above for electroplating. The above-described embodiments and embodiments therefore also apply to this process.As a further aspect of the present invention, a coated substrate with a particle-containing nickel layer or a particle-containing nickel alloy layer is described. The particle-containing nickel or nickel alloy layer comprises: - 100 parts by weight of nickel or a nickel alloy, and - a total of 0.5 to 250 parts by weight of at least one type of particle selected from inorganic piezoelectric particles, electrically conductive ceramic particles and combinations thereof. According to a preferred embodiment, the particle-containing nickel layer consists of nickel, the particles and any unavoidable impurities. The nickel alloy typically consists of 65 wt.%, preferably 75 wt.% or more, more preferably 85 wt.% or more, even more preferably 90 wt.% or more, of nickel. The nickel alloy contains in particular - 0 wt.% or more and 20 wt.-% or less of a further metal selected from transition metals, noble metals and combinations thereof, and - 0 wt.% or more and 15 wt.% or less of an element selected from B, P, S, Se, Te, C and combinations thereof, and the remainder consists of nickel and any unavoidable impurities. The nickel alloy contains a further metal and / or one of the elements. The further metal is different from nickel. Unavoidable impurities can arise, for example, from the decomposition of electrolyte components and lead, for example, to the incorporation of carbon, oxygen, nitrogen and / or boron. According to a preferred embodiment, the nickel alloy of a particle-containing nickel alloy layer contains - 0 wt.% or more and 15 wt.% or less, preferably 0 wt.% or more and 10 wt.% or less, more preferably 0 wt.% or more and 5 wt.-% or less of another metal selected from transition metals, noble metals, and combinations thereof; and - 0 wt.% or more and 10 wt.% or less, preferably 0 wt.% or more and 5 wt.% or less, of an element selected from B, P, S, Se, Te, C, and combinations thereof, in particular P, Se, and / or S, and the remainder consists of nickel and any unavoidable impurities. The nickel alloy contains another metal and / or one of the elements. The particle-containing nickel or nickel alloy layer typically forms an outermost layer on the coated substrate. The particles are at least partially arranged on the surface of the particle-containing nickel or nickel alloy layer, such that they form part of the surface of the particle-containing nickel or nickel alloy layer or the outermost layer of the coated substrate.The particle-containing nickel or nickel alloy layer contains the particles in particular in an amount of 1 to 200 parts by weight, preferably 5 to 150 parts by weight, more preferably 10 to 100 parts by weight, based on 100 parts by weight of nickel in the case of a particle-containing nickel layer or nickel alloy in the case of a particle-containing nickel alloy layer. The coated substrate with the particle-containing nickel or nickel alloy layer is obtainable by the method for electroplating a substrate with a particle-containing nickel or nickel alloy layer using the dispersion electrolyte according to at least one embodiment described herein or the method for electrolessly plating a substrate with a particle-containing nickel or nickel alloy layer using the bath according to at least one embodiment described herein. The advantages described above are therefore obtained.According to one embodiment, the coated substrate is obtained by the process for electroplating a particle-containing nickel or nickel alloy layer. The particle-containing nickel alloy then contains in particular - 0 wt.% or more and 20 wt.% or less, preferably 0 wt.% or more and 15 wt.% or less, more preferably 0 wt.% or more and 10 wt.% or less, even more preferably 0 wt.% or more and 5 wt.% or less, of a further metal selected from transition metals, noble metals, and combinations thereof, and - 0 wt.% or more and 15 wt.% or less, preferably 0 wt.% or more and 10 wt.% or less, more preferably 0 wt.% or more and 5 wt.% or less of an element selected from P, S, Se, Te, C, and combinations thereof, in particular P, Se, and / or S, and the remainder consists of nickel and any unavoidable impurities. The nickel alloy contains a further metal and / or one of the elements.The further metal preferably comprises or consists of Fe, Co, Mo, Cr, Cu, Zn, Sn, Bi, Sb and combinations thereof. More preferably, the further metal comprises or consists of one or more metals selected from Fe, Co, Mo and Cu. The substrate is a metallic or metallized substrate as described herein. The nickel alloy obtained by electrodeposition is preferably an alloy of Ni and Fe, Ni and Co, Ni and Mo, Ni and Cr, Ni and Cu, Ni and P, Ni and S, Ni and Se, Ni and Fe and P, Se and / or S, Ni and Co and P, Se and / or S, Ni and Mo and P, Se and / or S, Ni and Cr and P, Se and / or S, or Ni and Cu and P, Se and / or S, in each case with any unavoidable impurities. According to one embodiment, the coated substrate is obtained by the process for the electroless deposition of a particle-containing nickel or nickel alloy layer. The particle-containing nickel alloy then contains in particular - 0 wt.-% or more 20 wt.% or less, preferably 0 wt.% or more and 15 wt.% or less, more preferably 0 wt.% or more and 10 wt.% or less, even more preferably 0 wt.% or more and 5 wt.% or less, of a further metal selected from transition metals, noble metals and combinations thereof, - 0 wt.% or more and 15 wt.% or less, preferably 0 wt.% or more and 10 wt.% or less, of an element selected from B, P, S and combinations thereof, in particular P and / or S, and the remainder consists of nickel and any unavoidable impurities. The nickel alloy contains a further metal and / or one of the elements. The further metal is preferably selected from Fe, Pd, Re, Ru, Sn, Cu, Co, Bi, Au and combinations thereof. The further metal is particularly preferably selected from Fe, Co, Sn, Bi and combinations thereof. The substrate is one of the substrates described above in connection with the methods.Furthermore, the optional and preferred embodiments described above apply analogously to the coated substrate. This applies in particular to the substrate coated with the particle-containing nickel or nickel alloy layer, the layer thicknesses, the particle sizes, the optional additional particles, and the optional gradient of the particles. If present, the additional particles of a conductive carbon material are present in the particle-containing layer in an amount of 1 to 100 parts by weight, preferably 2 to 50 parts by weight, more preferably 3 to 30 parts by weight, based on 100 parts by weight of nickel in the case of a particle-containing nickel layer or nickel alloy in the case of a particle-containing nickel alloy layer.The total amount of particles typically does not exceed 250 parts by weight, preferably not 200 parts by weight, more preferably not 150 parts by weight, based on 100 parts by weight of nickel in the case of a particle-containing nickel layer or nickel alloy in the case of a particle-containing nickel alloy layer. The particle-containing nickel or nickel alloy layer is particularly mechanically stable and corrosion-resistant in the weakly acidic, neutral, and alkaline range, i.e., in a pH range of 4 or more, in particular 6 or more. According to a further embodiment, the particle-containing nickel or nickel alloy layer has a hardness of at least HV 200 (Vickers hardness), preferably at least HV 300, and more preferably at least HV 400. The measurement is carried out on the surface in accordance with DIN EN ISO 14577-1 (2015-11). The hardness can be adjusted, in particular, via the particle content and, if present, the content of other particles.The coated substrate is corrosion-resistant in weakly acidic and especially alkaline media and, compared to a substrate coated with a corresponding nickel or nickel alloy layer without the particles, exhibits a reduced overvoltage in aqueous alkaline media. The coated substrate can therefore be used, for example, as an electronic component, in particular as a switch, contact, electrode, or other component of an electrochemical cell. It is preferably used as an electrode of an electrochemical cell, for example in chlor-alkali electrolysis or the electrolysis of water or aqueous alkaline media, such as for the formation of oxygen and hydrogen. It can be used independently as an anode, as a cathode, or as an anode and as a cathode.The dispersion electrolyte according to the invention and the bath according to the invention can therefore be used to produce an electronic component, in particular to produce a switch, a contact, an electrode, and a component of an electrochemical cell, preferably an electrode. As a further aspect, the present invention provides an electrochemical cell comprising the coated substrate according to at least one embodiment. The coated substrate preferably serves as an electrode. It can be used independently of one another as an anode, as a cathode, preferably as an anode, and as a cathode. Examples of an electrochemical cell are a redox flow battery, a fuel cell, and an electrolyzer. According to one embodiment, the coated substrate is used as the cathode of an electrolyzer.The anode can then likewise be a coated substrate according to the invention or another electrode, for example made of nickel or nickel alloy or an electrode coated with nickel or nickel alloy. Examples The present invention is illustrated below by examples. It is not limited to these examples. Measurement methods The following measurement methods were used. 1) Layer thickness The layer thickness was measured using a Fischerscope X-Ray XDAL fluorescence measuring device in accordance with DIN EN ISO 3497 (2001-12). An averaged measured value is given. 2) Composition The composition of the particle-containing nickel or nickel alloy layer was also analyzed by X-ray fluorescence analysis on the coated substrate surface using the aforementioned device in accordance with DIN EN ISO 3497 (2001-12). The measured area was approximately 200 x 150 µm. The measured values ​​are obtained with an accuracy of ± 2 wt.% or better.3) Vickers Hardness The hardness test was carried out according to DIN EN ISO 14577-1 (2015-11) on the surface of the deposited layer, if necessary after polishing (i.e., conditioning). The Vickers hardness is indicated by the symbol "HV." A weight of 200 g was used as the test force. The test duration was 10 s. The Vickers hardness is specified dimensionlessly. Preparation of the metallic substrates: Stainless steel sheets (1.4404) measuring 50 x 120 x 0.4 mm were used for the tests. These were pretreated as follows: 1. Degreasing: SLOTOCLEAN AK 160 65 degreaser. o C 5 min 2 Rinse water RT* 3 Pickling aqueous HCl, 18%, with SLOTOCLEAN BEF 30 RT 10 s 4 Rinse water RT 5 Cathodic degreaser SLOTOCLEAN EL DCG, 6 A / dm 2 RT 2 min Degreasing 6 Rinsing water RT 7 Pickling aqueous HCl, 10% RT 30 s 8 Rinsing water RT 9 Deposition Nickel Strike, 3 A / dm 2RT 6 min interlayer *RT = room temperature Reagents The following reagents were used for the tests, among others. Slotoclean AK 160 (contains NaOH and disodium metasilicate), SLOTOCLEAN EL DCG (contains NaOH, disodium metasilicate and sodium carbonate), and SLOTOCLEAN BEF 30 (contains but-2-yne-1,4-diol and ethoxylated isotridecanol) are products from Dr.-Ing. Max Schlötter. Nickel Strike: Nickel electrolyte for the electrodeposition of the interlayer, from Dr.-Ing. Max Schlötter, containing 180 g / L NiCl2∙6H2O according to DIN 50970, 8 g / L HCl (concentrated), water Nickel sulfamate bath MS: Nickel sulfamate solution in water from Dr.-Ing. Max Schlötter, containing 160 g / L nickel ions, pH 4.0 SLOTONIK M: Bath additive from Dr.-Ing. Max Schlötter, containing 3 to 5 wt.% alkyl ether sulfate as sodium salt, alkyl group C12-14, polyethylene glycol ether with an average of 2 ethylene oxide units.Barium titanate (BaTiO3, perovskite structure): particle size 0.8 µm (aspect ratio < 3.0) from Sigma Aldrich, CAS: 12047-27-7 Boron nitride (BN, hexagonal): particle size approximately 1 µm, flake-shaped (aspect ratio > 3.0) from Sigma-Aldrich, CAS: 10043-11-5 Titanium nitride (TiN): particle size <3 µm (aspect ratio < 3.0) from Sigma Aldrich, CAS: 25583-20-4 Tamol. ® : Naphthalenesulfonic acid-formaldehyde polycondensates (sodium salts) from BASF SE Examples 1 to 9 and Comparative Example 1 Preparation of the electrolytes For Examples 1 to 9 and Comparative Example 1 (VB1), electrolytes with the following components were prepared in a glass beaker (2 L): - 375 mL / L nickel sulfamate bath MS (corresponds to 60 g / L nickel) - 34 g / L NiCl2∙6H2O (corresponds to 8.4 g / L nickel) - 45 g / L boric acid - 8 mL / L SLOTONIK M (bath additive with dispersant) - 0.9 g / L tamoxifen ®(Dispersant) - distilled water - barium titanate (BaTiO3), boron nitride (BN) or titanium nitride (TiN) according to Table 1 For this purpose, NiCl2·6H2O, dispersant and boric acid were first added to a mixture of distilled water, the nickel sulfamate solution and the bath additive and dissolved while stirring (500 rpm) at 60°C. For dissolution, the pH was adjusted to 4.1 by adding KOH. Then, powdered barium titanate (BaTiO3) in Examples 1 to 3, powdered boron nitride (BN) in Examples 4 to 6 and powdered titanium nitride (TiN) in Examples 7 to 9 were slowly added and dispersed while stirring (500 rpm). In Comparative Example 1, no particles were added. The pH was adjusted to 4.0 by adding sulfamic acid. The electrolyte volume was 2 L in each case.Table 1 BaTiO3 (perovskite- BN (hexagonal) TiN structure) [g / L] [g / L] [g / L] Example 1 1 - - Example 2 20 - - Example 3 40 - - Example 4 - 1 - Example 5 - 10 - Example 6 - 20 - Example 7 - - 1 Example 8 - - 10 Example 9 - - 20 Comparative Example 1 - - - Electroplating Stainless steel sheets were pretreated as described above and precoated with a nickel layer. The metallic substrates obtained in this way were each electroplated as follows. The electrolyte was mixed in a glass beaker (2 L) using a stirring bar (40 mm) (500 rpm). The stainless steel sheets were each connected as the cathode and immersed 10 cm deep into the electrolyte. Two Ni electrodes (25 x 120 x 5 mm) served as the anode, arranged parallel to the cathode on either side at a distance of 4 cm. The anodes were also immersed at a depth of 10 cm.The two parallel anodes were connected in series with the electrolyte, the cathode, and a direct current source. Deposition was carried out at 60°C and a current density of 2.5 A / dm. 2for 20 min. Assessment of the deposited layers In examples 1 to 9 and in comparative example 1 (VB1), dense, pore-free and well-adhering nickel layers were deposited. The layer thicknesses were approximately 10 µm. Figs. 1 to 3 show scanning electron microscope images of examples 1 to 3 at a magnification of 3000. In example 1, at a concentration of 1 g / L in the dispersion electrolyte, individual barium titanate particles were integrated into the nickel layer. At the higher concentrations of 20 g / L and 40 g / L barium titanate in the dispersion electrolytes of examples 2 and 3, more particles were incorporated into the layer, as can be seen in Figs. 2 and 3. Particles on the surface of the nickel layer appear as lighter, sharply defined areas. Larger, round, dark areas indicate deeper-lying, nickel-coated particles. Fig.1 to 3 demonstrate that barium titanate particles were incorporated into the respective nickel layer and are partially arranged on the surface of the nickel layer. In Examples 2 and 3 in particular, the incorporation occurred quite evenly across the entire surface. Fig. 4 shows a micrograph of Comparative Example 1 without particles in the nickel layer at a magnification of 500. Cross-sections of the coated substrates showed that the barium titanate particles were also homogeneously deposited inside the particle-containing nickel layer of Examples 1 to 3. Figs. 5A, 6A and 7 show optical microscope images of the cross-section of the coated substrates of Examples 2 and 3 and of Comparative Example 1. In Figs. 5A and 6A the particles in the coating can already be seen. Figs. 5B and 6B show scanning electron microscope images of the cross-sections of Example 2 and Example 3, respectively, at a magnification of 1500.Figures 8 to 10 show scanning electron microscope images of Examples 4, 5, and 6 at a magnification of 5000 for Example 4 (Fig. 8) and 2000 for Examples 5 and 6 (Figs. 9 and 10, respectively). From Fig. 8, it can be seen that boron nitride was already incorporated into the nickel layer at a concentration in the dispersion electrolyte of 1 g / L. As can be seen in Fig. 9, at a concentration of 10 g / L, more boron nitride particles were incorporated into the nickel layer. The piezoelectric, i.e., non-electrically conductive, boron nitride particles can be seen as bright areas in Fig. 9. The boron nitride particles thus form part of the surface of the particle-containing nickel layer. Agglomerates of several particles were occasionally observed. As can be seen in Fig. 10, at a concentration of 20 g / L in the dispersion electrolyte, significantly more boron nitride particles were incorporated into the nickel layer.Particularly in Examples 5 and 6, the incorporation occurred quite uniformly across the entire layer. Cross-sections of the coated substrates of Examples 4, 5, and 6 again revealed homogeneous incorporation of the boron nitride particles within the layer. Figures 11A and 12A show optical microscope images of cross-sections of Example 5 and Example 6, respectively. Figures 11B and 12B show scanning electron microscope images of these. Figures 13 to 15 show scanning electron microscope images of Examples 7, 8, and 9 at a magnification of 500. Figure 13 demonstrates isolated incorporation of titanium nitride particles into the nickel layer at a concentration in the dispersion electrolyte of 1 g / L. In Examples 8 and 9, at higher concentrations of 10 g / L and 20 g / L, respectively, more titanium nitride particles were deposited with the layer (see Fig. 14 and 15, respectively).Cross-sections of the coated substrates of Examples 7, 8, and 9 again revealed a homogeneous incorporation of the titanium nitride particles within the coating. Figures 16A and 17A show optical microscope images of cross-sections of Example 8 and Example 9, respectively. Figures 16B and 17B show scanning electron microscope images of these. The composition was determined for Examples 2, 3, 6, 8, 9, and Comparative Example 1 (VB1) (see Table 2). Table 2 Example / 2 3 6 8 9 VB1 Element [wt.%] [wt.%] [wt.%] [wt.%] [wt.%] [wt.%] B - - 7.8 - - - C 8.0 7.3 9.6 7.5 5.5 6.5 N - - 3.4 4.5 10.4 - O 4.7 11.0 2.7 3.3 3.5 3.8 Ni 74.6 44.0 76.5 76.6 58.0 89.7 Ti 2.7 11.4 - 8.0 22.4 - Ba 9.9 26.4 - - - - The measured amounts of C and O are assumed to be due to natural impurities or electrolyte components. In examples 2 and 3, part of the O content is due to the barium titanate particles.The incorporation of barium titanate, boron nitride and titanium nitride could be confirmed based on the measured compositions. The Vickers hardness (HV) was also determined. The results are summarized in Table 3. Table 3 Particles in the electrolyte HV Comparative example 1 - 166 Example 1 1 g / L BaTiO3 412 Example 2 20 g / L BaTiO3610 Example 3 40 g / L BaTiO3 643 Example 4 1 g / L BN 412 Example 5 10 g / L BN 432 Example 6 20 g / L BN 452 Example 7 1 g / L TiN 379 Example 8 10 g / L TiN 593 Example 9 20 g / L TiN 629 The incorporation of the particles was accompanied by an increase in the Vickers hardness of the layer. Measurement of overvoltages The overvoltages were determined in an electrochemical cell from Gaskatel (Flexcell PP) with a sample area of ​​3 cm. 2The overpotentials were measured for the alkaline electrolysis of water in 30% aqueous KOH. The potential at which a current flow was observed was determined for the evolution of hydrogen (HER) or oxygen (OER). The coated substrate was used as an electrode in a chamber and connected as the cathode or anode, respectively. A standard hydrogen electrode (Gaskatel Hydroflex) served as the reference electrode. The counter electrode used consisted of wound Pt wire. The overpotential was the measured potential at 25°C for a current of -10 mA (-3.3 mA / cm 2 ) minus the theoretical potential of 0 V for hydrogen (HER) or at 25°C for a current of 10 mA (3.3 mA / cm 2) minus the theoretical potential of +1.23 V for oxygen (OER). The smaller the magnitude of the overpotential, i.e., the closer the measured value is to 0, the lower the overpotential. The results are summarized in Table 4.

[0002] Table 4 Particles in the electrolyte HER [V] OER [V] Comparative example 1 - -1.09 +0.17 Example 1 1 g / L BaTiO3-0.78 +0.26 Example 2 20 g / L BaTiO3 -0.54 +0.29 Example 3 40 g / L BaTiO3-0.38 +0.29 Example 4 1 g / L BN -0.81 +0.24 Example 5 10 g / L BN -0.78 +0.21 Example 6 20 g / L BN -0.33 +0.31 Example 7 1 g / L TiN -0.55 +0.27 Example 8 10 g / L TiN -0.53 +0.30 Example 9 20 g / L TiN -0.58 +0.29 Compared to comparative example 1, even the incorporation of small amounts of The total overpotentials were reduced by approximately 0.2 V using piezoelectric barium titanate in Example 1 and piezoelectric boron nitride in Example 4. The overpotential for hydrogen formation was significantly reduced; a slight increase occurred for oxygen formation. This effect was significantly enhanced by the increased incorporation of barium titanate particles in Examples 2 and 3 and by the increased incorporation of boron nitride particles in Examples 5 and 6.In Examples 3 and 6, the overvoltages were reduced by a total of approximately 0.6 V. It was observed that the overpotential for hydrogen formation could be significantly reduced. A slight increase was observed for oxygen formation compared to Comparative Example 1. This confirms that the incorporation of piezoelectric barium titanate particles or piezoelectric boron nitride particles can reduce overvoltages in aqueous alkaline media. A greater reduction in the overpotential was observed at higher particle concentrations. Even with titanium nitride, an electrically conductive ceramic material, a significant reduction in the overpotential of approximately 0.4 V was observed even with a low particle content in the dispersion electrolyte of Example 7.In contrast to the piezoelectric materials barium titanate and hexagonal boron nitride, no further reduction in the overpotential was observed by increasing the particle concentration in the nickel layer; instead, the overpotential remained approximately constant. It is possible that the electrically conductive ceramic titanium nitride reduces the overpotential through a different mechanism than the piezoelectric particles in Examples 1 to 6. As shown in Examples 1 to 9, the coated substrates from Examples 1 to 9 are suitable as anodes and, in particular, as cathodes for electrolysis in aqueous alkaline media. Significantly reduced overpotentials were measured, particularly for the cathode reaction, i.e., the formation of hydrogen.

Claims

Patent claims 1. Dispersion electrolyte for the galvanic deposition of particle-containing nickel or nickel alloy layers, comprising: - nickel ions in a concentration of 2 to 200 g / L; - at least one type of particle selected from inorganic piezoelectric particles, electrically conductive ceramic particles and combinations thereof, in a total concentration of 1 to 200 g / L; - at least one dispersant selected from anionic dispersants, non-ionic dispersants and combinations thereof; - optionally ions of at least one further metal selected from transition metals, noble metals and combinations thereof, in a total concentration of up to 40 g / L;- optionally at least one non-metal compound other than the dispersant and selected from phosphorus compounds, sulfur compounds, selenium compounds, tellurium compounds, carbon compounds, and combinations thereof, in a total concentration of up to 50 g / L; and - water, wherein the dispersion electrolyte has a pH of 2.0 to 7.

0.

2. The dispersion electrolyte according to claim 1, wherein the particles are made of BN (hexagonal), AlN, ZnO, GaPO4, M1; 2y MA 1- M1 2y MA 1- TiN, TiC, TiB2, Ti2CN, B4C, WC and combinations thereof, and wherein in the general formulas the following applies: M1 is in each case independently at least one element selected from Li, Na and K, preferably Li; MA is in each case independently at least one element selected from Ca, Sr, Ba, Pb and La; MB is selected from Zr, Hf, Mn, Mg 1 / 3 Nb 2 / 3 , Mg 1 / 3 V 2 / 3 , Mg1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ; MC is selected from Hf, Mn, Mg 1 / 3 Nb 2 / 3 , Mg 1 / 3 V 2 / 3 , Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ; MD is selected from Hf, Mg 1 / 3 Nb 2 / 3 , Mg 1 / 3 V 2 / 3 , Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ; ME is selected from Mg 1 / 3 Nb 2 / 3 , Mg 1 / 3 V 2 / 3 , Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ; MF is selected from V, Ta and Mn; MG is selected from Ta and Mn; MH is Mn; x each independently satisfies 0 ≤ x ≤ 1; and y each independently satisfies 0 ≤ y ≤ 1.

3. Dispersion electrolyte according to claim 2, wherein the particles are made of BN (hexagonal), AlN, ZnO, GaPO4, Li2[Zr x Ti 1−x ]O3, Li 2y MA 1-y [Zr x Ti 1−x ]O3, MA[Zr x Ti 1−x ]O3, Pb[Zr x Ti 1−x]O3, LaMnO3 and LiNbO3 and combinations thereof, and wherein MA is each independently at least one element selected from Ca, Sr and Ba; x each independently satisfies 0 ≤ x ≤ 1; and y each independently satisfies 0 < y < 1.

4. Dispersion electrolyte according to any one of the preceding claims, wherein in the dispersion electrolyte the weight ratio of nickel ions to the ions of the further metal is 80:20 or more, preferably 85:15 or more, more preferably 90:10 or more, even more preferably 95:5 or more, and / or the weight ratio of nickel ions to the total of the phosphorus atoms, sulfur atoms, selenium atoms, tellurium atoms and carbon atoms in the at least one non-metal compound is 85:15 or more, preferably 90:10 or more, more preferably 95:5 or more. 5.Dispersion electrolyte according to one of the preceding claims, wherein the further metal comprises at least one element selected from Fe, Co, Mo, Cr, Cu, Zn, Sn, Bi, Sb and combinations thereof, and / or the non-metal compound comprises at least one compound selected from hypophosphites, a urea, a thiourea, a thiocyanate, selenourea, lithium bis(trifluoromethanesulfonyl)imide, dimethyltelluride. a xanthate, a carbamate, a ketone, an aromatic aldehyde, Turkey red oil, and combinations thereof.

6. The dispersed electrolyte according to any one of the preceding claims, wherein the dispersant comprises at least one anionic dispersant selected from sulfate compounds containing an alkyl group, an aralkyl group, or an aromatic group, each having up to 30 carbon atoms, sulfonate compounds containing an alkyl group, an aralkyl group, or an aromatic group, each having up to 30 carbon atoms, and carboxy- or carboxylate-containing polymers. 7.The dispersion electrolyte according to claim 6, wherein the anionic dispersant comprises at least one first anionic dispersant selected from sulfate compounds having an alkyl group with 6 to 24 carbon atoms, sulfate compounds having an aralkyl group with 6 to 24 carbon atoms, and combinations thereof, and at least one second anionic dispersant selected from sulfonate compounds having an aromatic group with 6 to 24 carbon atoms. 8.A bath for the electroless deposition of particle-containing nickel or nickel alloy layers, comprising: - nickel ions in a concentration of 2 to 200 g / L; - at least one type of particle selected from inorganic piezoelectric particles, electrically conductive ceramic particles, and combinations thereof, in a total concentration of 1 to 200 g / L; - at least one dispersant selected from anionic dispersants, non-ionic dispersants, and combinations thereof. - optionally, ions of a further metal selected from transition metals, noble metals, and combinations thereof, in a total concentration of up to 50 g / L; - at least one reducing agent capable of reducing nickel ions to nickel and, if present, the ions of the further metal to the further metal; and - water, wherein the bath has a pH of 3.0 to 12.

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9. Bath according to claim 8, wherein the reducing agent comprises at least one reducing agent selected from hypophosphites, dimethylaminoborane, NaBH4, a thiourea, a thiocyanate, and combinations thereof, and / or wherein the further metal is selected from Fe, Pd, Re, Ru, Sn, Cu, Co, Bi, Au, and combinations thereof. 10.A method for electroplating a substrate with a particle-containing nickel or nickel alloy layer, comprising electroplating the particle-containing nickel or nickel alloy layer on a metallic or metallized substrate using the dispersion electrolyte according to any one of claims 1 to 7 at a temperature of 20 to 85°C.

11. A method for electrolessly coating a substrate with a particle-containing nickel or nickel alloy layer, comprising electrolessly depositing the particle-containing nickel or nickel alloy layer on a substrate using the bath according to claim 8 or 9 at a temperature of 15°C to 95°C.

12. A coated substrate with a particle-containing nickel or nickel alloy layer, wherein the particle-containing nickel or nickel alloy layer contains - 100 parts by weight of nickel or nickel alloy, and. - a total of 0.5 to 250 parts by weight of at least one type of particles selected from inorganic piezoelectric particles, electrically conductive ceramic particles, and combinations thereof.

13. The coated substrate according to claim 12, wherein the nickel alloy contains at least 65 wt.% nickel.

14. The coated substrate according to claim 12, wherein the nickel alloy contains - 0 wt.% or more and 20 wt.% or less of another metal selected from transition metals, noble metals, and combinations thereof; and - 0 wt.% or more and 15 wt.% or less of an element selected from B, P, S, Se, Te, C, and combinations thereof, and the remainder consists of nickel and any unavoidable impurities, and wherein the nickel alloy contains another metal and / or one of the elements. 15.The coated substrate of claim 14, wherein the further metal is selected from Fe, Co, Mo, Cr, Cu, Zn, Sn, Bi, Sb, and combinations thereof, and the element is selected from P, S, Se, Te, C, and combinations thereof, or the further metal is selected from Fe, Pd, Re, Ru, Sn, Cu, Co, Bi, Au, and combinations thereof, and the element is selected from B, P, S, and combinations thereof.

16. An electrochemical cell comprising the coated substrate of any one of claims 12 to 15.