Composite material and its use in electrochemical applications and electrode coatings made therefrom

Abstract

The invention relates to a composite material having an elemental composition consisting of 30 to 70 wt% of nickel; 5 to 20 wt% of molybdenum; 2 to 10 wt% of chromium; 2 to 10 wt% of X, wherein X is one or more elements selected from the group consisting of cerium, cobalt, copper, gadolinium, lanthanum, lithium, magnesium, niobium, praseodymium, samarium, scandium, strontium, tantalum, titanium, tungsten, ytterbium, yttrium and mixtures thereof; and optionally up to 30 wt% of oxygen, wherein the balance of the composite metal and metal oxide material consists of aluminum or zinc or mixtures thereof and unavoidable impurities. The invention also relates to the use of the composite material of the invention in the production of electrochemical catalyst systems, electrodes for energy storage or energy conversion applications. Finally, the invention relates to an electrode comprising a substrate coated with the composite material according to the invention.

Description

Technical Field

[0001] This invention relates to composite materials and their use in electrochemical applications. Background Technology

[0002] Electrochemical processes and devices are gaining increasing popularity and commercial relevance. There is high demand for electrochemical energy storage systems, such as batteries for automobiles, bicycles, and handheld devices, as well as capacitors or supercapacitors for electronic storage or short-term energy storage applications. Electrochemical energy conversion systems hold promise as a cornerstone of the green economy, for example, as fuel cells, electrolyzers, or for producing electronic fuels.

[0003] All these processes require suitable surfaces where electrochemical reactions can occur, particularly on the electrodes of rechargeable batteries, electrolyzers, and fuel cells. These are called electrocatalysts.

[0004] As is well known, besides depending on the chemical composition and surface structure of the electrode and electrocatalyst, the suitability of the electrode and electrocatalyst also largely depends on the electrical impedance and conductivity of the surface where the electrochemical reaction occurs. Depending on the requirements of specific applications, there is an ongoing need to improve the surface properties of functional electrodes and electrocatalysts.

[0005] Those skilled in the art will know that the catalytic activity on the surface of a functional electrode is limited by (i) surface activation resistance and (ii) resistance (ohmic resistance).

[0006] The low catalytic activity on the surface of the functional electrode necessitates the application of a high overpotential to the electrode for the chemical reaction to proceed smoothly. Conversely, reducing the surface activation resistance leads to increased catalytic activity, thereby reducing the voltage required to initiate the chemical reaction at the functional electrode.

[0007] The low conductivity on the functional electrode surface leads to reduced surface reaction efficiency due to decreased mass transfer and increased accumulation of inactive materials. Electrodes are typically manufactured using polymer binders that hold catalyst particles together. The presence of such binders reduces the conductivity of the electrode, thereby reducing the conductivity of the entire system. Summary of the Invention

[0008] This invention is defined by the appended claims.

[0009] Specifically, the present invention is embodied as a composite material having an elemental composition comprising: 30 to 70 wt% nickel; 5 to 20 wt% molybdenum; 2 to 10 wt% chromium; 2 to 10 wt% X, wherein X is one or more elements selected from the group consisting of cerium, cobalt, copper, gadolinium, lanthanum, lithium, magnesium, niobium, praseodymium, samarium, scandium, strontium, tantalum, titanium, tungsten, ytterbium, yttrium, and mixtures thereof; and optionally up to 30 wt% oxygen, wherein the balance of the composite material consists of aluminum or zinc or mixtures thereof and unavoidable impurities. All wt% indications are relative to the total weight of the composite material. It has been found that improved performance can be achieved by using functional electrodes coated with the composite material according to the present invention. As used herein, when X is a mixture of two or more elements selected from the group consisting of cerium, cobalt, copper, gadolinium, lanthanum, lithium, magnesium, niobium, praseodymium, samarium, scandium, strontium, tantalum, titanium, tungsten, ytterbium and yttrium, the total amount of X in the composite material of the present invention is 2 to 10 by weight.

[0010] According to a preferred embodiment of the present invention, the nickel content of the composite material may be 35 to 65% by weight, for example 40 to 53% by weight.

[0011] According to a preferred embodiment of the present invention, the molybdenum content of the composite material may be 5 to 15% by weight, for example 10 to 13% by weight.

[0012] According to a preferred embodiment of the present invention, the chromium content of the composite material may be 3 to 6% by weight of chromium, for example 4 to 5% by weight of chromium.

[0013] According to a preferred embodiment of the present invention, the content of element X in the composite material can be 2 to 6% by weight of X, for example 3 to 5% by weight of X.

[0014] According to a preferred embodiment of the present invention, the oxygen content of the composite material may be 0.2 to 28% by weight of oxygen, for example 2 to 28% by weight of oxygen, for example 5 to 15% by weight of oxygen.

[0015] According to a preferred embodiment of the present invention, the content of aluminum or zinc or a mixture thereof in the composite material may be 4 to 38% by weight of aluminum or zinc or a mixture thereof, for example 10 to 30% by weight of aluminum or zinc or a mixture thereof.

[0016] According to a single embodiment of the invention, the composite material may have an elemental composition comprising: 53 to 63 wt% nickel, 6 to 10 wt% molybdenum, 3 to 4 wt% chromium, 3 to 4 wt% x, and 15 to 27 wt% oxygen, wherein the balance of the composite material consists of aluminum or zinc or mixtures thereof, and unavoidable impurities. According to this embodiment, the weight of the metal oxide phase in the composite material may be 18 to 48 wt%. According to this embodiment, the composite material may be present as a coating having a thickness of 10 to 1000 μm, preferably 70 to 400 μm, and a surface area of ​​1.2 to 30,000 m². 2 / m 2 Such as, for example, 2 to 25,000 m 2 / m 2 For example, 200 to 20,000 m 2 / m 2 .

[0017] According to one embodiment of the invention, the composite material may have an elemental composition comprising: 35 to 40 wt% nickel, 13 to 15 wt% molybdenum, 4 to 6 wt% chromium, 3 to 5 wt% X, and optionally up to 4 wt% oxygen, wherein the balance of the composite material consists of aluminum or zinc or mixtures thereof, and unavoidable impurities. According to this embodiment, the weight of the metal oxide phase may be 6 to 15 wt% based on the total weight of the metal alloy matrix composite material. Also according to this embodiment, the composite material may be in the form of a coating with a thickness of 10 to 1000 μm, preferably 70 to 400 μm, and a surface area of ​​1.0 to 200 m². 2 / m 2 Such as, for example, 1.2 to 30,000 m 2 / m 2 For example, 2 to 25,000 m 2 / m 2 For example, 200 to 20,000 m 2 / m 2 .

[0018] According to another embodiment of the invention, the elements aluminum and zinc in the content of aluminum or zinc or mixtures thereof may be partially or completely substituted for each other.

[0019] Another part of the invention is the use of the composite material according to any one of the preceding claims in the production of electrochemical catalyst systems or in electrodes for energy storage or energy conversion applications.

[0020] Another part of the invention is a thin-film electrode comprising a coated substrate formed of a composite material according to the invention in the form of a coating, the coating having a thickness of 10 to 1000 μm, preferably 70 to 400 μm, and a surface area of ​​1.0 to 30,000 m². 2 / m 2 . Attached Figure Description

[0021] The invention will be further described with reference to the following figures: Figure 1 A schematic diagram of a metal alloy matrix composite material having a dispersed metal oxide phase according to one aspect of the present invention is shown; Figure 2 A micrograph of a metal alloy matrix composite material having a dispersed metal oxide phase, according to one aspect of the present invention, is shown. The micrograph was taken using a scanning electron microscope equipped with an electron backscatter diffraction detector (EBSD). Figure 3 A schematic diagram of the battery configuration used to measure the iV curve and impedance spectrum data of Example 2 is shown; Figure 4 The current-voltage curves of a prior art electrode and an electrode prepared according to Example 2 are shown; Figure 5 The Nyquist plots of the cells with prior art electrodes and electrodes prepared according to Example 2 are shown at 0.05 A / cm², measured by electrochemical impedance spectroscopy (EIS). Figure 6 The Nyquist plots of the cells with prior art electrodes and electrodes prepared according to Example 2 are shown at 2 A / cm².

[0022] It should be understood that the following description and accompanying drawings relate to exemplary embodiments of the invention and should not limit the scope of the claims. Detailed Implementation

[0023] According to the appended claims, the present invention provides a composite material that can be used to prepare coatings for functional electrodes to achieve improved electrical properties.

[0024] According to the present invention, a composite material having the elemental composition described above is provided. The composite material according to the present invention is suitable for coating functional electrode surfaces and electrocatalysts, thereby improving their chemical and physical surface properties for higher efficiency and activity in electrochemical applications.

[0025] In particular, since low catalytic activity is a challenge that necessitates the application of high overpotentials, according to the present invention, catalytic activity is improved by: (a) synergistic effects between different elements of the alloy (e.g., Ni-Mo-Cr-X-(Al or Zn)), which increases intrinsic surface activity and reduces the Tafel slope of the reaction; and (b) increased active surface area, thereby reducing the overpotential.

[0026] Furthermore, since no adhesive is required to apply the composite material according to the invention to the surface of the functional electrode, the problem of low conductivity on the surface of the functional electrode is alleviated. In addition, the addition of chromium and element X, as well as molybdenum, reduces the formation of the insulating passivation phase and the magnetic properties of Ni, thereby improving surface conductivity. This effect is particularly significant when element X is copper.

[0027] It should be noted that, in addition to mutually exclusive combinations of features, the present invention may include any combination of the features and / or limitations mentioned herein. The foregoing description pertains to specific embodiments of the invention and is intended to illustrate those embodiments. However, it will be apparent to those skilled in the art that many modifications and variations can be made to the embodiments described herein. All such modifications and variations are intended to fall within the scope of the invention as defined by the appended claims.

[0028] Example 1 - Production of the Initial Coating In the following description, an initial coating is formed by converting a raw material powder into a functional electrode atop a substrate. To achieve this, the raw material powder is provided via vacuum melting and inert gas atomization. This method allows for a high level of process control and maintains a low oxygen content. Preferably, the oxygen content at this stage is below 5 ppm by weight. The elemental composition of the raw material powder corresponds to the elemental composition required for the initial coating. The particle size distribution of the raw material powder obtained after gas atomization is suitable for thermal spraying applications. The particle size range is from 0.5 μm to 220 μm. In a preferred embodiment, the particle size distribution is d10 = 5 μm and d90 = 45 μm, as determined using a laser diffraction particle size distribution analyzer. If desired, the powder obtained after gas atomization can be graded to obtain the desired particle size range.

[0029] The obtained raw material powder is then transformed into a functional electrode atop a substrate. This is accomplished through thermal spraying using a custom-designed stacking spray gun on a multi-grid structured substrate. Ar can be used as the primary forming gas, while N2 or H2, or mixtures thereof, can be used as auxiliary gases. The raw material powder is injected into the thermal spraying flame through an external nozzle, where the enthalpy is in the range of 20 to 40 MJ / kg. The heated and accelerated particles impact the multi-grid substrate to form the electrode.

[0030] The thickness of the initial coating, as measured by a micrometer, can range from 10 to 1000 μm. The elemental composition of the initial coating is approximately 35 to 40 wt% Ni, approximately 13 to 15 wt% Mo, approximately 34 to 38 wt% Al, approximately 4 to 6 wt% Cr, approximately 3 to 5 wt% X, and approximately 2 to 4 wt% O.

[0031] Example 2 - Activation of the initial coating Although the initial coating exhibits good performance as an electrode in electrochemical applications, it can be further activated to improve its performance. For this purpose, the initial coating can be immersed in an activation solution at 80°C to 90°C for 24 hours. The activation solution can be a mixture of water and 10 to 40 wt% KOH and 1 to 10 wt% potassium sodium tartrate tetrahydrate solution.

[0032] Activation treatment was used to increase the surface area of ​​the coating. While the thickness of the electrode material remained essentially constant from 70 to 400 μm, the surface area increased significantly. The surface area of ​​the electrode was measured using a BELSORP-max X instrument with gas adsorption based on Brunauer-Emmett-Teller (BET) analysis. Three × 3.5 g dry solid samples were used, with nitrogen as the adsorbed gas. The average surface area of ​​the three samples is reported. The elemental composition of the activated coating was approximately 53 to 63 wt% Ni, approximately 6 to 10 wt% Mo, approximately 4 to 8 wt% Al, approximately 3 to 4 wt% Cr, approximately 3 to 4 wt% X, and approximately 15 to 27 wt% O.

[0033] Example 3: Study on electrochemical performance Next, current-voltage characteristics and electrochemical impedance spectroscopy (EIS) measurements were performed on the nickel cathode of the prior art and the cathode coated with the composite material obtained in Example 2 above.

[0034] Electrode preparation The nickel electrode used for comparison is a simple perforated nickel plate. It is compared with the cathode coated with a composite material obtained in Example 2 above.

[0035] Electrode testing The electrodes were tested in a zero-gap electrolytic cell, such as... Figure 3 The diagram is schematic. The electrolytic cell consists of four main components: nickel bipolar plates, a nickel wire mesh as a current collector, a test electrode, and a Zirfon PERL UTP500 as a diaphragm.

[0036] Tests were conducted at atmospheric pressure, 70°C, and 30 wt% KOH. After activation for 30 minutes at a constant current of 0.2 A, the KOH was activated using a biopotentialostat at 10 mA s⁻¹.-1 The scanning rate was used to record the polarization curve.

[0037] EIS measurements were performed at both low and high current densities, and plots were generated from 50 kHz to 100 MHz to determine ohmic and activation losses. Operating conditions and electrolyzer hardware remained constant for all tests. Nyquist plots were fitted using RelaxIS software.

[0038] result Figure 4 The current-voltage curves show that, compared with nickel electrodes, the intrinsic surface activity of electrodes coated with the composite material according to the present invention is significantly improved.

[0039] As in Figure 5 and Figure 6 As can be seen, the electrode according to the invention provides a lower activation resistance (according to...). Figure 5 Impedance spectroscopy measurements at low current densities) and low ohmic resistance (according to Figure 6 Impedance spectroscopy measurements at high current densities), thus leading to Figure 4 The improved current-voltage measurement characteristics are shown.

Claims

1. A composite material, consisting of elements comprising: -30 to 70% by weight of nickel; -5 to 20% by weight of molybdenum; -2 to 10% by weight of chromium; -2 to 10% by weight of X, where X represents one or more elements selected from the group consisting of cerium, cobalt, copper, gadolinium, lanthanum, lithium, magnesium, niobium, praseodymium, samarium, scandium, strontium, tantalum, titanium, tungsten, ytterbium, yttrium, and mixtures thereof, and -Optionally up to 30% by weight of oxygen, The balance of the composite metal and metal oxide materials consists of aluminum or zinc or mixtures thereof, as well as unavoidable impurities, and The weight percentage indicates the total weight of the composite material.

2. The composite material according to claim 1, wherein the amount of nickel in the elemental composition is 35 to 65% by weight, for example 40 to 53% by weight.

3. The composite material according to any one of the preceding claims, wherein the amount of molybdenum in the elemental composition is 5 to 15% by weight, for example 10 to 13% by weight.

4. The composite material according to any one of the preceding claims, wherein the amount of chromium in the elemental composition is 3 to 6% by weight, for example, 4 to 5% by weight of chromium.

5. The composite material according to any one of the preceding claims, wherein the amount of element X in the elemental composition is 2 to 6% by weight of X, for example 3 to 5% by weight of X.

6. The composite material according to any one of the preceding claims, wherein the amount of oxygen in the elemental composition is from 0.2 to 28% by weight, for example from 5 to 15% by weight.

7. The composite material according to any one of the preceding claims, wherein the amount of aluminum or zinc or a mixture thereof in the elemental composition is 4 to 38% by weight, for example 10 to 30% by weight.

8. The composite material according to any one of the preceding claims is a metal alloy matrix composite material having a dispersed metal oxide phase.

9. The composite material according to any one of the preceding claims, wherein the elements aluminum and zinc in the content of aluminum or zinc or mixtures thereof are partially or completely substituted for each other.

10. The composite material according to any one of claims 1 to 9, wherein the composite material comprises elements consisting of: The composite material comprises 53 to 63% by weight of nickel, 6 to 10% by weight of molybdenum, 3 to 4% by weight of chromium, 3 to 4% by weight of X and 15 to 27% by weight of oxygen, wherein the balance of the composite material consists of aluminum or zinc or mixtures thereof and unavoidable impurities.

11. The composite material according to any one of claims 1 to 9, wherein the composite material comprises elements consisting of: The composite material comprises 35 to 40% by weight of nickel, 13 to 15% by weight of molybdenum, 4 to 6% by weight of chromium, 3 to 5% by weight of X, and optionally up to 4% by weight of oxygen, wherein the balance of the composite material consists of aluminum or zinc or mixtures thereof, and unavoidable impurities.

12. The composite material according to claim 11, having a metal oxide content of 6 to 15% by weight.

13. Use of the composite material according to any one of the preceding claims in the production of electrochemical catalyst systems or in electrodes for energy storage or energy conversion applications.

14. A thin-film electrode comprising a coated substrate, wherein the coating is composed of a composite material according to any one of claims 1 to 12, and has a thickness of 70 to 400 μm and a surface area of ​​1.0 to 30,000 μm. 2 / m 2 Surface area.

15. The thin-film electrode of claim 14, wherein the coating is composed of the composite material of claims 1 to 9, 11, or 12, and has a thickness of 1.0 to 200 μm. 2 / m 2 or 1.1 to 20 m 2 / m 2 or 1.2 to 2 m 2 / m 2 Surface area.

16. The thin-film electrode of claim 14, wherein the coating is composed of the composite material of claims 1 to 10 and has a thickness of 200 to 30,000 μm. 2 / m 2 or 2,000 to 25,000 m 2 / m 2 or 5,000 to 20,000 m 2 / m 2 Surface area.

Images