Preparation method and application of high-stable catalyst for metal-air battery

Abstract

This invention discloses a method for preparing a highly stable catalyst for metal-air batteries, belonging to the field of battery catalysis technology. The method involves first heating Mn, B, and a transition metal together to a molten state, then rapidly ejecting the alloy liquid using a single-roller quenching device to obtain initial Mn-based B-doped strips. These initial strips are then uniformly dispersed in a platinum salt solution to obtain platinum-coated Mn-based B-doped strips. Finally, the platinum-coated Mn-based B-doped strips are placed in a vacuum tube furnace for simultaneous vapor-phase Mn removal and high-temperature thermal reduction of platinum, yielding the highly stable catalyst. This invention employs a "melt spinning-impregnation-vapor-phase dealloying" strategy, achieving stable loading of Pt clusters while constructing a porous support through vapor-phase Mn removal. This invention enables dual-function oxygen-electricity activity in metal-air batteries and utilizes Pt-B bonds to bridge the porous support and Pt clusters, thereby extending the cycle life of the electrode.

Description

Technical Field

[0001] This invention belongs to the field of battery catalysis technology, specifically a method for preparing and applying a highly stable catalyst for metal-air batteries. Background Technology

[0002] Metal-air batteries are chemical power sources with high theoretical energy density, long operating time, and high safety, typically used as emergency backup power, off-grid power, and range extender power for automobiles. The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) occurring at the cathode of these batteries during charging and discharging are both four-electron processes, resulting in slow kinetics. Furthermore, factors such as electrode activation and resistive polarization cause both charging and discharging voltages to deviate from the theoretical potential, leading to low actual efficiency of metal-air batteries. Currently, RuO2 and Pt / C are the best OER and ORR catalysts, respectively, significantly reducing charge and discharge voltage deviations. However, their high cost, poor stability, and single-atom activity severely hinder their practical application. While single-atom catalysts (such as Pt-SAC and Fe-NC) can overcome catalytic activity limits, they suffer from significant drawbacks in stability, mass production, and system compatibility. Therefore, there is an urgent need to design and prepare a bifunctional oxygen electrocatalyst for metal-air batteries to lower the reaction energy barrier and achieve efficient and stable charging and discharging. Summary of the Invention

[0003] The purpose of this invention is to solve the problems existing in the prior art and to provide a method for preparing a highly stable catalyst for metal-air batteries and its application.

[0004] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for preparing a highly stable catalyst for metal-air batteries, comprising the following steps: Step S1: Heat Mn, B and transition metal together to a molten state, and use a single-roll quenching device to quickly throw out the alloy liquid to obtain Mn-based B-doped initial strips.

[0005] Step S2: The Mn-based B-doped initial bands obtained in step S1 are uniformly dispersed in a platinum salt solution to obtain platinum salt-coated Mn-based B-doped initial bands.

[0006] Step S3: Place the platinum salt-coated Mn-based B-doped initial strips obtained in step S2 into a vacuum tube furnace, and simultaneously perform gas-phase Mn removal and high-temperature thermal reduction of platinum to obtain B-doped porous transition metal compound-supported platinum clusters, which is the highly stable catalyst.

[0007] Furthermore, in step S1 of the above preparation method, the atomic percentage of Mn is 60% to 95%, the atomic percentage of B is 1% to 10%, and the balance is a transition metal.

[0008] Furthermore, in step S1 of the above preparation method, the transition metal is one of Fe, Co, Ni, Cu, V, Cr, and Ti, or a mixture of several in any proportion.

[0009] Furthermore, in step S2 of the above preparation method, the platinum salt in the platinum salt solution is one of chloroplatinic acid, ammonium chloroplatinate, platinum nitrate, and platinum acetylacetonate, and the concentration of the platinum salt solution is 0.001 to 0.1 mol / L.

[0010] Furthermore, in step S3 of the above preparation method, the vacuum degree of the vacuum tube furnace is 10. -4 ~1 Pa, temperature 800~1000℃, treatment time 0.25~24h.

[0011] In a second aspect, the present invention provides an application of the highly stable catalyst prepared by the above method as a working electrode, a platinum wire as an auxiliary electrode, and Ag / AgCl as a reference electrode for electrocatalytic OER / ORR testing.

[0012] In a third aspect, the present invention provides the application of the highly stable catalyst prepared by the above preparation method as a bifunctional catalyst for the cathode of a metal-air battery for battery performance testing.

[0013] This invention employs a "melt spinning-impregnation-vapor phase dealloying" strategy, which simultaneously achieves stable loading of Pt clusters while constructing a porous support through vapor phase de-Mn removal. The highly stable catalyst of this invention for metal-air batteries can achieve both OER-ORR bifunctional activity and, moreover, utilize Pt-B bonds to bridge the porous support and Pt clusters, thereby extending the electrode's cycle life.

[0014] The porous support in this invention, used in a highly stable catalyst for metal-air batteries, possesses an ultra-large specific surface area, providing not only excellent mass transfer channels for electrochemical reactions but also ample space for Pt loading. The boron (B) element in the porous support can form stable Pt-B bonds with the surface-loaded Pt, not only stably bridging the porous support and Pt clusters but also promoting the Pt clusters to a near-zero valence state. The porous support, rich in unsaturated coordination bonds and defects, spontaneously forms an oxide protective layer on the surface of the Pt clusters, i.e., forming metal-support interaction (MSI), which further enhances the stability of the supported catalyst. In this structure, the Pt clusters exhibit a uniform dispersion and ultra-low loading, significantly improving the utilization rate of precious metals and reducing costs.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Mn is used as the extraction component of the initial alloy. On the one hand, its high saturated vapor pressure helps to selectively extract under high vacuum; on the other hand, it is widely available, inexpensive and easy to recycle.

[0016] (2) Mn sublimates in atomic form under high vacuum and high temperature conditions and undergoes thermal reduction reaction with the platinum salt coated on the surface, so that while forming a porous carrier, the ligament surface is uniformly loaded with small-sized platinum elements (such as platinum atoms and platinum clusters).

[0017] (3) The B element in the porous support can form a stable Pt-B bond with the Pt element loaded on the surface, which on the one hand stabilizes the porous support and Pt clusters, and on the other hand promotes the Pt clusters to approach the near-zero valence state.

[0018] (4) Due to the abundance of unsaturated coordination bonds and defects, porous supports will spontaneously form an oxide protective layer on the surface of Pt clusters, that is, form metal-support interaction (MSI), which can further improve the stability of supported catalysts. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The image shows the X-ray diffraction pattern of the highly stable catalyst prepared in Example 1 of this invention.

[0021] Figure 2 This is a scanning electron microscope image of the highly stable catalyst prepared in Example 1 of the present invention.

[0022] Figure 3 This is a Pt elemental distribution diagram of the highly stable catalyst prepared in Example 1 of the present invention.

[0023] Figure 4 This is a transmission electron microscope image of the highly stable catalyst prepared in Example 1 of the present invention.

[0024] Figure 5 This is a spherical aberration electron microscope image of the highly stable catalyst prepared in Example 1 of the present invention.

[0025] Figure 6 This is a synchrotron radiation diagram of the highly stable catalyst prepared in Example 1 of the present invention.

[0026] Figure 7 This is an oxygen evolution polarization curve during the test process of Example 5 of the present invention.

[0027] Figure 8 This is an oxygen reduction polarization curve of the test process in Example 5 of the present invention.

[0028] Figure 9 This is a cyclic charge-discharge curve of a zinc-air battery used in Embodiment 6 of the present invention. Detailed Implementation

[0029] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore merely examples and should not be used to limit the scope of protection of the present invention. It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning understood by those skilled in the art to which this invention pertains. Example 1

[0030] This embodiment provides a method for preparing a highly stable catalyst for metal-air batteries, comprising the following steps: Step S1: Mn, B, and Co are heated together in an atomic percentage ratio of 65:5:30 to a molten state. The molten alloy is then rapidly ejected using a single-roll quenching device to obtain an initial Mn-based B-doped strip, denoted as Mn. 65 Co 30 B5 initial strip.

[0031] Step S2: Take the Mn obtained in step S1 65 Co 30 The initial B5 band was uniformly dispersed in a 0.002 mol / L chloroplatinic acid solution to obtain chloroplatinic acid-coated Mn. 65 Co 30 B5 initial strip.

[0032] Step S3: Coat Mn with the chloroplatinic acid obtained in step S2. 65 Co 30 The initial B5 strip was placed in a vacuum tube furnace at a vacuum level of 10. -3 At a temperature of 850℃ and a time of 1 hour, gas-phase Mn removal and high-temperature thermal reduction of platinum were carried out simultaneously to obtain platinum clusters supported on boron-doped porous MnCo compounds (Pt / np-BMnCo), which is the highly stable catalyst described above.

[0033] The highly stable catalyst prepared by the method in Example 1 was subjected to relevant tests, and the specific test results are as follows: like Figure 1 As shown, X-ray diffraction patterns revealed that MnO, Pt, and CoB peaks could be detected simultaneously in the prepared platinum clusters supported by B-doped porous MnCo compounds (Pt / np-BMnCo).

[0034] like Figure 2 and Figure 3 As shown in the scanning electron microscope image, the prepared platinum clusters supported by the B-doped porous MnCo compound (Pt / np-BMnCo) exhibit a typical bicontinuous porous-ligament structure, while Pt nanoparticles are uniformly loaded on its surface.

[0035] like Figure 4 As shown in the transmission electron microscopy (TEM) images, it was found that the Pt particles in the prepared B-doped porous MnCo compound-supported platinum clusters (Pt / np-BMnCo) did not agglomerate and had a size of approximately 2 nm.

[0036] like Figure 5 As shown, spherical aberration electron microscopy revealed that in the prepared B-doped porous MnCo compound supported platinum clusters (Pt / np-BMnCo), a MnO protective layer spontaneously forms on the surface of the Pt particles, i.e., metal-support interaction (MSI) is formed, which can further improve the stability of the supported catalyst.

[0037] like Figure 6 As shown, Pt-B and Pt-Pt bonds can be detected by synchrotron radiation, confirming that there is a bridging effect between the B-doped porous support and Pt particles, which helps to improve the stability of the loaded electrode. Example 2

[0038] This embodiment provides a method for preparing a highly stable catalyst for metal-air batteries, comprising the following steps: Step S1: Mn, B, and V are heated together in an atomic percentage ratio of 60:10:30 to a molten state. The molten alloy is then rapidly ejected using a single-roll quenching device to obtain an initial Mn-based B-doped strip, denoted as Mn. 60 V 30 B 10 Initial stripe.

[0039] Step S2: Take the Mn obtained in step S1 60 V 30 B 10 The initial bands were uniformly dispersed in a 0.001 mol / L ammonium chloroplatinate solution to obtain ammonium chloroplatinate-coated Mn. 60 V 30 B 10 Initial stripe.

[0040] Step S3: Coat Mn with the ammonium chloroplatinate obtained in step S2. 60 V 30 B 10 The initial strip was placed in a vacuum tube furnace with a vacuum level of 10. -4At a temperature of 1000℃ and a time of 0.25h, gas-phase Mn removal and high-temperature thermal reduction of platinum were carried out simultaneously to obtain platinum clusters supported by boron-doped porous MnV compounds, which is the highly stable catalyst described above. Example 3

[0041] This embodiment provides a method for preparing a highly stable catalyst for metal-air batteries, comprising the following steps: Step S1: Mn, B, and Ni are heated together in an atomic percentage ratio of 85:8:7 to a molten state. The molten alloy is then rapidly ejected using a single-roll quenching device to obtain an initial Mn-based B-doped strip, denoted as Mn. 85 Ni7B8 initial strip.

[0042] Step S2: Take the Mn obtained in step S1 85 The initial Ni7B8 bands were uniformly dispersed in a 0.05 mol / L platinum nitrate solution to obtain platinum nitrate-coated Mn. 85 Ni7B8 initial strip.

[0043] Step S3: Coat Mn with platinum nitrate obtained in step S2. 85 The initial Ni7B8 strip was placed in a vacuum tube furnace at a vacuum level of 10. -1 At a temperature of 800℃ and a duration of 12 hours, gas-phase Mn removal and high-temperature thermal reduction of platinum were carried out simultaneously to obtain platinum clusters supported on B-doped porous MnNi compounds, which is the highly stable catalyst described above. Example 4

[0044] This embodiment provides a method for preparing a highly stable catalyst for metal-air batteries, comprising the following steps: Step S1: Mn, B, and Ti are heated together in an atomic percentage ratio of 95:1:4 to a molten state. The molten alloy is then rapidly ejected using a single-roll quenching device to obtain an initial Mn-based B-doped strip, denoted as Mn. 95 Ti4B1 initial stripe.

[0045] Step S2: Take the Mn obtained in step S1 95 The initial Ti4B1 bands were uniformly dispersed in a 0.1 mol / L platinum acetylacetonate solution to obtain platinum acetylacetonate-coated Mn. 95 Ti4B1 initial stripe.

[0046] Step S3: Coat Mn with platinum acetylacetone obtained in step S2. 95 The initial Ti4B1 strip was placed in a vacuum tube furnace at a vacuum level of 1 Pa and a temperature of 1000 °C for 24 hours. Simultaneously, gas-phase Mn removal and high-temperature thermal reduction of platinum were carried out to obtain platinum clusters supported on B-doped porous MnTi compounds, which is the highly stable catalyst. Example 5

[0047] The platinum cluster supported on a boron-doped porous MnCo compound (Pt / np-BMnCo) prepared by the method in Example 1 was used as the working electrode, a platinum wire as the auxiliary electrode, and Ag / AgCl as the reference electrode for electrocatalytic OER / ORR testing.

[0048] like Figure 7 and Figure 8 As shown, using the prepared boron-doped porous MnCo compound supported on platinum clusters (Pt / np-BMnCo) as the working electrode, platinum wire as the auxiliary electrode, and Ag / AgCl as the reference electrode, electrocatalytic OER was performed. The results showed that this electrode achieved a current density of 100 mA / cm². 2 It requires only 1.7 V oxygen evolution potential, exhibiting OER activity exceeding that of RuO2; electrocatalytic ORR was conducted and found that the half-wave potential of this electrode was 0.89 V, second only to the ORR activity of commercial Pt / C. Example 6

[0049] The platinum clusters (Pt / np-BMnCo) supported on the boron-doped porous MnCo compound prepared by the method in Example 1 were used as bifunctional catalysts for the cathode of metal-air batteries, and their battery performance was tested.

[0050] like Figure 9 As shown, the prepared B-doped porous MnCo compound supported on platinum clusters (Pt / np-BMnCo) was used as a bifunctional catalyst for the cathode of a zinc-air battery, with a zinc sheet as the anode and KOH+Zn(Ac)2 as the electrolyte. After battery cycling tests, it was found that the electrode did not show any degradation even after continuous cycling for 2200 hours, while RuO2+Pt / C showed significant degradation after cycling for 200 hours.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for preparing a highly stable catalyst for metal-air batteries, characterized in that, Includes the following steps: Step S1: Heat Mn, B and transition metal together to a molten state, and use a single-roller quenching device to quickly throw out the alloy liquid to obtain Mn-based B-doped initial strips; Step S2: The Mn-based B-doped initial bands obtained in step S1 are uniformly dispersed in a platinum salt solution to obtain platinum salt-coated Mn-based B-doped initial bands; Step S3: Place the platinum salt-coated Mn-based B-doped initial strips obtained in step S2 into a vacuum tube furnace, and simultaneously perform gas-phase Mn removal and high-temperature thermal reduction of platinum to obtain B-doped porous transition metal compound-supported platinum clusters, which is the highly stable catalyst.

2. The method for preparing a highly stable catalyst for metal-air batteries according to claim 1, characterized in that: In step S1, the atomic percentage of Mn is 60% to 95%.

3. The method for preparing a highly stable catalyst for metal-air batteries according to claim 1, characterized in that: In step S1, the atomic percentage of B is 1% to 10%.

4. The method for preparing a highly stable catalyst for metal-air batteries according to claim 1, characterized in that: In step S1, the transition metal is one of Fe, Co, Ni, Cu, V, Cr, and Ti, or a mixture of several in any proportion.

5. The method for preparing a highly stable catalyst for metal-air batteries according to claim 1, characterized in that: In step S2, the platinum salt in the platinum salt solution is one of chloroplatinic acid, ammonium chloroplatinate, platinum nitrate, and platinum acetylacetonate, and the concentration of the platinum salt solution is 0.001–0.1 mol / L.

6. The method for preparing a highly stable catalyst for metal-air batteries according to claim 1, characterized in that: In step S3, the vacuum level of the vacuum tube furnace is 10. -4 ~1 Pa, temperature 800~1000℃, treatment time 0.25~24h.

7. The application of the highly stable catalyst prepared by the preparation method according to any one of claims 1-6 as the working electrode, platinum wire as the auxiliary electrode, and Ag / AgCl as the reference electrode for electrocatalytic OER / ORR testing.

8. The highly stable catalyst prepared by the preparation method according to any one of claims 1-6 is used as a bifunctional catalyst for the cathode of a metal-air battery for battery performance testing.

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