CN106111997B - A kind of preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material - Google Patents

Abstract

The invention provides a method for preparing a porous nickel alloy electrolysis hydrogen cathode composite material, which is mainly used in the technical field of electrolysis hydrogen. The present invention adopts the powder reaction synthesis method, and five kinds of powders of Ni, Fe, Mo, C, and LaNi ₅ are prepared according to a certain ratio, wherein Fe, Mo, C, and LaNi ₅ powders account for 22.5~52wt% of the total content, and the formulated The good powder is mixed evenly, and 0.5~4% stearic acid is added, and after drying, the green body is obtained by pressure molding, and the green body is vacuum sintered by using the principle of solid phase partial diffusion to obtain Ni‑Fe‑Mo‑C/ LaNi ₅ porous electrolysis hydrogen cathode material. The porous electrolysis hydrogen composite cathode material prepared by the present invention has the advantages of large specific surface area, low hydrogen evolution overpotential, good catalytic performance, excellent corrosion resistance, stable working performance, simple and environmentally friendly preparation process, etc., and is of great significance to the development of hydrogen energy. .

Description

Preparation method of porous nickel alloy electrolysis hydrogen composite cathode material

technical field

The invention relates to a preparation technology of a porous nickel alloy material, in particular to a preparation method of a composite cathode material for electrolysis of hydrogen.

Background technique

As an efficient and clean secondary energy source, hydrogen energy is regarded as one of the most promising new energy sources in the future. The large-scale use of hydrogen energy will enable human beings to enter a sustainable green age, and the production of large quantities of cheap hydrogen is an important prerequisite for the development and utilization of hydrogen energy. At present, common hydrogen production methods include water electrolysis hydrogen production, biological hydrogen production, photocatalytic hydrogen production and fossil fuel hydrogen production. Among the many hydrogen production methods, the electrolytic water hydrogen production technology has the most significant advantages: low cost of raw materials for hydrogen production, wide resources, low equipment cost, high purity of hydrogen, and no carbon emissions. However, due to the high overpotential and poor stability of the hydrogen evolution electrode in the current electrolytic water hydrogen production technology, the production energy consumption is relatively large, which limits the large-scale application of this technology. Therefore, it is of great significance to improve the hydrogen evolution catalytic activity and electrocatalytic stability of the electrode.

The electron configuration of the transition metal Ni is [Ar]3d ⁸ 4s ² , which has unpaired 3d electrons. In the hydrogen evolution electrocatalytic reaction, it can pair with the 1s orbital of the hydrogen atom to form a moderately strong Ni-H adsorption bond. Excellent hydrogen evolution catalytic performance and price advantage, so it is recognized as an ideal replacement material for noble metals. In order to improve the catalytic activity of cathode hydrogen evolution electrodes, the development of nickel-based electrodes mainly has three directions: porous electrodes, alloy electrodes and composite electrodes. By increasing the real surface area of the porous electrode, the number of catalytic active centers increases, and the apparent catalytic activity of the electrode is improved, thereby greatly improving the electrolysis efficiency. Alloy electrodes include Ni-metal and Ni-nonmetal alloys. According to Engel-Brewer's "volcano" theory, metals to the left of the transition system with unfilled or half-filled d orbitals (such as Fe, Co, Ni) and transition systems with paired d electrons that are not suitable for bonding in pure metals When the metals on the right (such as W, Mo, Cr, La, Ha, Zr) are melted into alloys, they can have a very obvious electrocatalytic synergistic effect on the hydrogen evolution reaction. Such as the patent CN102719846, on the three-dimensional nickel mesh substrate, the Ni-Mo alloy coating is electrochemically deposited by controlling the electrodeposition potential and the concentration of Ni and Mo in the electrolyte, and then anodic etching is carried out in an ammonia solution to prepare a Ni-based three-dimensional mesh gradient Alloy hydrogen evolution cathode material. The alloy electrode material prepared by this technology has a high specific surface area, a hydrogen evolution overpotential of less than 100mV, and good catalytic performance. However, the electrochemical deposition used has environmental problems such as complex preparation process and waste water. It shows that by increasing the surface area and forming an alloy, the intrinsic catalytic activity of the electrode can be effectively improved, the electrolysis efficiency can be improved, and the energy consumption can be reduced. However, porous electrodes and alloy electrodes still have problems such as poor resistance to reverse current oxidation, unstable hydrogen evolution, easy peeling of the coating, and short service life. However, in the actual industrial operation process, power outages will inevitably occur. Porous electrodes and alloy electrodes are easily corroded and oxidized during power outages, greatly reducing the catalytic activity of hydrogen evolution; The hydrogen evolution activity is easily lost, resulting in increased energy consumption and even interruption of electrolysis. The composite electrode embeds second-phase solid particles (such as oxides, carbides, and hydrogen storage materials) in the matrix metal to form a composite alloy to achieve high catalytic performance. The hydrogen storage alloy powder LaNi ₅ particles have a strong ability to absorb hydrogen, so that when the power is turned off, the absorbed hydrogen is slowly released, preventing the electrode surface from being oxidized, that is, it plays a protective role. For example, the patent CN102899681 uses Ni as the matrix to embed LaNi ₅ and Al particles into the coating to obtain the Ni/(LaNi ₅ +Al) precursor through composite electrodeposition, and then uses the alkali solution method to dissolve the aluminum in the coating to obtain porous nickel. The composite electrode has excellent hydrogen evolution electrocatalytic performance and excellent stability.

The Ni-Fe-Mo-C/LaNi ₅ porous electrode prepared by the powder reaction synthesis method in the present invention has a relatively high specific surface area, a low hydrogen evolution overpotential, relatively excellent corrosion resistance, and good short circuit resistance. The advantages of good stability, high mechanical strength, simple preparation process and environmental protection are of great significance to the development and application of hydrogen energy.

Contents of the invention

The present invention provides a method for preparing a porous nickel alloy electrolytic hydrogen composite cathode material aiming at the disadvantages of low catalytic activity, poor corrosion resistance, poor power-off and short-circuit resistance, unstable hydrogen evolution, and complicated preparation process of the existing hydrogen evolution electrode. .

The invention provides a preparation method of a porous nickel alloy electrolysis hydrogen composite cathode material. The specific preparation method comprises the following steps:

(1) Powder preparation: five powders of Ni, Fe, Mo, C, and LaNi ₅ are prepared in a certain proportion, wherein Fe, Mo, C, and LaNi ₅ powders account for 22.5-52wt% of the total content;

(2) Powder mixing: Mix the prepared powder evenly, add stearic acid, and dry for 5-14 hours;

(3) Pressure forming: the dried powder is subjected to cold isostatic pressing to obtain a green body;

(4) Green body sintering: put the green body in a vacuum furnace, keep the heating rate of 10-15°C/min from room temperature to 100-130°C, keep it warm for 20-40min; The heating rate is raised to 250-300°C, and the temperature is kept for 20-40min; then the temperature is raised to 350-380°C at a heating rate of 3-10°C/min and kept at this temperature for 20-40min; The heating rate is raised to 490-550°C and kept at this temperature for 30-50 minutes; then the temperature is raised to 590-640°C at a heating rate of 3-10°C/min and kept at this temperature for 50-80 minutes; The heating rate of °C/min is raised to 800-1000 °C and kept at this temperature for 30-50 min; cooled to room temperature with the furnace, and the inventive porous electrolysis hydrogen cathode material is obtained.

Preferably, the Ni powder in step (1) has a powder particle size of 3-5 μm, and a percentage of 48-77.5 wt%. .

Preferably, the powder particle size of the Fe powder in step (1) is 3-5 μm, and the percentage is 20-30 wt%.

Preferably, the particle size of the Mo powder in step (1) is 3-5 μm, and the percentage is 1-10 wt%.

Preferably, the percentage of powder C in step (1) is 1-10 wt%.

Preferably, the particle size of the LaNi ₅ alloy powder in step (1) is 10-80 μm, and the percentage of LaNi ₅ powder is 0.5-2 wt%.

Preferably, the amount of stearic acid added in step (2) is 0.5-4% of the total mass fraction of the powder.

Preferably, the pressure for powder molding in step (3) is 50 MPa-250 MPa, and the holding time is 2-3 minutes.

Preferably, the degree of vacuum in the vacuum furnace in step (4) is 1×10 ^-2 Pa˜1×10 ^-3 Pa.

Preferably, the C powder used in step (1) is carbon black, and the LaNi ₅ powder is an AB ₅ type hydrogen storage alloy.

The present invention adopts the advantage of above-mentioned technical scheme to be:

(1) The internal pores are abundant and the specific surface area is large. The present invention utilizes partial diffusion between element powders during the sintering process to generate a large number of pores. The pores inside the material are criss-crossed and interpenetrated with each other. The porosity is 30% to 60%, and the pore diameter is 1 to 10 μm. The micron-scale porous structure is convenient for gas transmission, and has Facilitate the hydrogen evolution reaction.

(2) The hydrogen evolution overpotential is low and the catalytic performance is good. The invention utilizes the catalytic synergy between Mo, Ni and Fe to reduce the hydrogen evolution overpotential and improve the catalytic activity of the electrode; the pores formed by sintering are used to increase the surface roughness of the material, increase the specific surface area, increase the number of catalytic active centers, and improve the efficiency of electrolysis. High efficiency and good catalytic performance.

(3) Excellent corrosion resistance and good stability. In the present invention, nickel with excellent corrosion resistance is selected as the alloy matrix, which can resist medium corrosion; the hydrogen storage function of LaNi ₅ is used to avoid the cathode discharge reaction of hydrogen adsorption during the intermittent electrolysis of the electrode and the long-term power failure process. The dissolution of the active ingredient plays a protective role and improves the stability of the electrode material.

(4) Excellent mechanical properties and long service life. The nickel alloy electrolysis hydrogen composite cathode material obtained by the solid phase sintering preparation technology has the advantages of excellent mechanical properties, high mechanical strength, good toughness, high temperature resistance, wear resistance, long service life, etc., and meets the actual industrial application requirements.

(5) Economical and environmentally friendly, industrialized production is possible. The powders of Ni, Fe, Mo, and C elements used in the present invention have a wide range of sources and low prices; the present invention adopts powder reaction synthesis and preparation technology, which has high raw material utilization rate, low preparation cost, short and controllable process, and no industrial waste water is produced. It is beneficial to environmental protection and suitable for industrial scale production.

Description of drawings

FIG. 1 is a surface topography diagram of the Ni-Fe-Mo-C/LaNi ₅ porous electrode prepared in Example 1.

Fig. 2 is the cathodic polarization curve of the Ni-Fe-Mo-C/LaNi ₅ porous electrode prepared in Example 1.

detailed description

Representative examples of the present invention are provided in the following, which are illustrative only and are not intended to limit the scope of the invention described herein, and are merely illustrative of embodiments of the invention.

Example 1

Five kinds of powders of Ni, Fe, Mo, C, and LaNi ₅ are prepared in proportion, wherein Fe content is 25wt%, powder particle size is 3μm; Mo content is 5wt%, powder particle size is 3μm; C content is 5wt%; The content of LaNi ₅ is 1 wt%, and the particle size of the powder is 80 μm. Put the prepared powder on a V-type powder mixer and mix it at a constant speed for 10 hours, then add stearic acid of 2% of the total powder mass, dry for 10 hours, and cold-press at a pressure of 250 MPa under a cold press for about 2 minutes. ;Place the pressed sample in a vacuum furnace, keep the temperature rising rate of 10°C/min under the condition of vacuum degree of 1×10 ^-2 Pa, raise the temperature from room temperature to 100°C, and keep it for 30 minutes; The heating rate is raised to 250°C and kept for 30 minutes; then the temperature is raised to 350°C at a rate of 10°C/min and kept at this temperature for 30 minutes; the temperature is then raised to 490°C at a rate of 10°C/min Keep warm for 30 minutes; then raise the temperature to 590°C at a heating rate of 10°C/min and keep it at this temperature for 60 minutes; then raise the temperature to 800°C at a heating rate of 10°C/min and keep it at this temperature for 40 minutes, then cool with the furnace to At room temperature, the obtained material is the porous nickel alloy electrolysis hydrogen composite cathode material. The microscopic surface topography of the obtained material is shown in Fig. 1 . As shown in Figure 1, the material has abundant interconnected pores, and the distribution of pores is uniform, and the pore size ranges from 1 μm to 10 μm.

In order to study the catalytic hydrogen evolution performance of the porous nickel alloy electrolytic hydrogen evolution composite cathode material, the fired sample was fixed and sealed with epoxy resin to leave a geometric surface area of 1 cm ² , and electrochemical tests were carried out in 6mol/L KOH solution. The standard three-electrode system was used in the electrochemical test: the auxiliary electrode was a platinum sheet; the reference electrode was Hg/HgO; the working electrode was a sintered Ni-Fe-Mo-C/LaNi ₅ porous electrode. The testing instrument used in the present invention is a CS350 electrochemical workstation, the scanning speed is 1mV·s ^-1 , the scanning range is 0V～-2V, and the testing temperature is maintained at 30°C in a constant temperature water bath. Before the test, the electrodes were scanned by cyclic voltammetry -1.0V～0.2V in order to activate the electrodes and remove impurities and unstable substances on the surface of the electrodes. The cathodic polarization curve of the Ni-Fe-Mo-C/LaNi ₅ porous electrode is shown in Figure 2. When the electrode potential reaches -1.6V, the current density is 0.30A/cm ² .

Example 2

Five kinds of powders of Ni, Fe, Mo, C, and LaNi ₅ are prepared in proportion, wherein Fe content is 30wt%, powder particle size is 3μm; Mo content is 10wt%, powder particle size is 3μm; C content is 10wt%; The content of LaNi ₅ is 2wt%, and the particle size of the powder is 80μm. Put the prepared powder on a V-type powder mixer and mix it at a constant speed for 10 hours, add 1% stearic acid of the total powder mass, and then dry it for 8 hours, and then cold press it under a cold press at a pressure of 200 MPa. The holding time is about 2min; put the pressed sample in a vacuum furnace, and keep the temperature rising rate of 10℃/min under the condition of vacuum degree of 1×10 ^-2 Pa; Raise the temperature to 280°C at a heating rate of 1 min and keep it warm for 30 minutes; then raise the temperature to 360°C at a heating rate of 10°C/min and keep it at this temperature for 40 minutes; then raise the temperature to 500°C at a heating rate of 10°C/min and Keep it warm for 30 minutes; then raise the temperature to 600°C at a heating rate of 10°C/min and keep it at this temperature for 70 minutes; then raise the temperature to 920°C at a heating rate of 10°C/min and keep it at this temperature for 30 minutes, then cool with the furnace to room temperature, the obtained material is the porous nickel alloy electrolysis hydrogen composite cathode material.

The sample preparation and electrochemical experiment steps in Example 1 were repeated, and then the electrochemical experiment was carried out to obtain similar pore structure and electrochemical performance as in Example 1.

Example 3

Five powders of Ni, Fe, Mo, C, and LaNi ₅ were prepared according to the proportion, wherein the content of Fe was 25wt%, the particle size of powder was 3μm; the content of Mo was 1wt%, the particle size of powder was 3μm; the content of C was 1wt%; The content of LaNi ₅ is 0.5wt%, and the particle size of the powder is 30μm. Put the prepared powder on a V-type powder mixer and mix it at a constant speed for 10 hours, add 1.5% stearic acid of the total mass of the powder, and then dry it for 9 hours. 3min; put the pressed sample in a vacuum furnace, and keep the temperature rising rate of 10℃/min under the condition of vacuum degree of 1×10 ^-2 Pa; Raise the temperature to 300°C at a heating rate of 1 min, and keep it warm for 20 minutes; then raise the temperature to 380°C at a heating rate of 10°C/min and keep it at this temperature for 20 minutes; then raise the temperature to 550°C at a heating rate of 10°C/min Keep warm for 40 minutes; then raise the temperature to 640°C at a heating rate of 10°C/min and hold at this temperature for 50 minutes; then raise the temperature to 1000°C at a heating rate of 10°C/min and hold at this temperature for 40 minutes, then cool with the furnace to room temperature, the obtained material is the porous nickel alloy electrolysis hydrogen composite cathode material.

The sample preparation and electrochemical experiment steps in Example 1 were repeated, and then the electrochemical experiment was carried out to obtain similar pore structure and electrochemical performance as in Example 1.

Example 4

Mix five kinds of powders of Ni, Fe, Mo, C, and LaNi ₅ in proportion, wherein Fe content is 28wt%, powder particle size is 3μm; Mo content is 5wt%, powder particle size is 3μm; C content is 2wt%; The content of LaNi ₅ is 0.5wt%, and the particle size of the powder is 50μm. Put the prepared powder on a V-type powder mixer and mix it at a constant speed for 10 hours, then add 3% stearic acid of the total powder mass, and then dry it for 12 hours. 3min; put the pressed sample in a vacuum furnace, and keep the temperature rising rate of 10℃/min under the condition of vacuum degree of 1×10 ^-2 Pa, from room temperature to 120℃, and keep it for 20min; Raise the temperature to 280°C at a heating rate of 1 min, and keep it for 20 minutes; then raise the temperature to 370°C at a heating rate of 10°C/min and keep it at this temperature for 20 minutes; then raise the temperature to 510°C at a heating rate of 10°C/min Keep warm for 30 minutes; then raise the temperature to 630°C at a heating rate of 10°C/min and hold at this temperature for 70 minutes; then raise the temperature to 940°C at a heating rate of 10°C/min and hold at this temperature for 40 minutes, then cool with the furnace to room temperature, the obtained material is the porous nickel alloy electrolysis hydrogen composite cathode material.

The sample preparation and electrochemical experiment steps in Example 1 were repeated, and then the electrochemical experiment was carried out to obtain similar pore structure and electrochemical performance as in Example 1.

Example 5

Mix five kinds of powders of Ni, Fe, Mo, C, and LaNi ₅ in proportion, wherein Fe content is 20wt%, powder particle size is 5μm; Mo content is 10wt%, powder particle size is 5μm; C content is 5wt%; The LaNi ₅ content is 1 wt%, and the powder particle size is 50 μm. Put the prepared powder on a V-type powder mixer and mix it at a constant speed for 10 hours, then add 2% stearic acid of the total powder mass, and then dry it for 9 hours, and cold press it under a cold press at a pressure of 50 MPa. The holding time is about 3min; put the pressed sample in a vacuum furnace, and keep the heating rate of 10℃/min under the condition of vacuum degree of 1×10 ^-2 Pa, from room temperature to 110℃, and keep it for 20min; Raise the temperature to 270°C at a heating rate of 1 min, and keep it for 20 minutes; then raise the temperature to 360°C at a heating rate of 10°C/min and keep it at this temperature for 20 minutes; then raise the temperature to 520°C at a heating rate of 10°C/min Keep warm for 30 minutes; then raise the temperature to 620°C at a heating rate of 10°C/min and hold at this temperature for 70 minutes; then raise the temperature to 900°C at a heating rate of 10°C/min and hold at this temperature for 40 minutes, then cool with the furnace to room temperature, the obtained material is the porous nickel alloy electrolysis hydrogen composite cathode material.

The sample preparation and electrochemical experiment steps in Example 1 were repeated, and then the electrochemical experiment was carried out to obtain similar pore structure and electrochemical performance as in Example 1.

Example 6

Five kinds of powders of Ni, Fe, Mo, C, and LaNi ₅ are prepared in proportion, wherein Fe content is 23wt%, powder particle size is 5μm; Mo content is 8wt%, powder particle size is 5μm; C content is 2wt%; The LaNi ₅ content is 1 wt%, and the powder particle size is 10 μm. Put the prepared powder on a V-type powder mixer and mix it at a constant speed for 10 hours, add stearic acid with 4% of the total mass of the powder, dry it for 10 hours, and cold press it under a cold press at a pressure of 100 MPa. The holding time is about 3min; put the pressed sample in a vacuum furnace, and keep the temperature rising rate of 10℃/min under the condition of vacuum degree of 1×10 ^-2 Pa; Raise the temperature to 300°C at a heating rate of 1 min, and keep it for 40 minutes; then raise the temperature to 380°C at a heating rate of 10°C/min and keep it at this temperature for 40 minutes; then raise the temperature to 530°C at a heating rate of 10°C/min Keep warm for 30 minutes; then raise the temperature to 600°C at a heating rate of 10°C/min and hold at this temperature for 60 minutes; then raise the temperature to 850°C at a heating rate of 10°C/min and hold at this temperature for 30 minutes, then cool with the furnace to room temperature, the obtained material is the porous nickel alloy electrolysis hydrogen composite cathode material.

The sample preparation and electrochemical experiment steps in Example 1 were repeated, and then the electrochemical experiment was carried out to obtain similar pore structure and electrochemical performance as in Example 1.

Example 7

Mix five kinds of powders of Ni, Fe, Mo, C, and LaNi ₅ in proportion, wherein Fe content is 22wt%, powder particle size is 5μm; Mo content is 5wt%, powder particle size is 5μm; C content is 3wt%; The content of LaNi ₅ is 2wt%, and the particle size of the powder is 50 μm. Put the prepared powder on a V-type powder mixer and mix it at a constant speed for 10 hours, then add 0.5% stearic acid of the total mass of the powder, and then dry it for 8 hours. 3min; put the pressed sample in a vacuum furnace, and keep the heating rate of 10℃/min under the condition of vacuum degree of 1×10 ^-2 Pa, from room temperature to 110℃, and keep it for 20min; Raise the temperature to 260°C at a heating rate of 1 min and keep it warm for 30 minutes; then raise the temperature to 370°C at a heating rate of 10°C/min and keep it at this temperature for 20 minutes; then raise the temperature to 520°C at a heating rate of 10°C/min and hold Keep warm for 40 minutes; then raise the temperature to 630°C at a heating rate of 10°C/min and hold at this temperature for 70 minutes; then raise the temperature to 960°C at a heating rate of 10°C/min and hold at this temperature for 30 minutes, then cool with the furnace to room temperature, the obtained material is the porous nickel alloy electrolysis hydrogen composite cathode material.

The sample preparation and electrochemical experiment steps in Example 1 were repeated, and then the electrochemical experiment was carried out to obtain similar pore structure and electrochemical performance as in Example 1.

The examples are used to illustrate the present invention, but not to limit the present invention. Any person skilled in the art can modify the embodiments without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be listed in the claims of the present invention.

Claims (10)

1. a kind of preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material, its specific preparation method include：

(1) powder is prepared：By Ni, Fe, Mo, C, LaNi₅Five kinds of powder prepare by a certain percentage, wherein Fe, Mo, C, LaNi₅Account for altogether 22.5~52wt% of total content；

(2) powder mixes：The powder prepared is well mixed, adds stearic acid, dries 5~14h；

(3) pressure forming：Dried powder is subjected to isostatic cool pressing, obtains green compact；

(4) green sintering：Green compact are placed in vacuum drying oven, keep 10~15 DEG C/min programming rate rise to 100 from room temperature~ 130 DEG C, it is incubated 20~40min；250~300 DEG C are warming up to 10~15 DEG C/min programming rate again, is incubated 20~40min； Then 350~380 DEG C are warming up to 3~10 DEG C/min programming rate and are incubated 20~40min at such a temperature；Again with 10~ 15 DEG C/min programming rate is warming up to 490~550 DEG C and is incubated 30~50min at such a temperature；Then with 3~10 DEG C/min Programming rate be warming up to 590~640 DEG C and at such a temperature be incubated 50~80min；Again with 10~15 DEG C/min heating speed Degree is warming up to 800~1000 DEG C and is incubated 30~50min at such a temperature；Cool to room temperature with the furnace, that is, obtain porous nickel alloy It is electrolysed liberation of hydrogen composite cathode material.

2. the preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material according to claim 1, it is characterised in that The powder diameter of Ni powder is 3~5 μm in the step (1), and percentage is 48~77.5wt%.

3. the preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material according to claim 1, it is characterised in that The powder diameter of Fe powder is 3~5 μm in the step (1), and percentage is 20~30wt%.

4. the preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material according to claim 1, it is characterised in that The powder diameter of Mo powder is 3~5 μm in the step (1), and percentage is 1~10wt%.

5. the preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material according to claim 1, it is characterised in that The percentage of C powder is 1~10wt% in the step (1).

6. the preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material according to claim 1, it is characterised in that LaNi in the step (1)₅The powder diameter of alloyed powder is 10~80 μm, LaNi₅The percentage of powder is 0.5~2wt%.

7. the preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material according to claim 1, it is characterised in that Stearic addition accounts for the 0.5~4% of powder total mass fraction described in step (2).

8. the preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material according to claim 1, it is characterised in that The pressure of powder compacting is 50MPa~250MPa in the step (3), and the dwell time is 2~3min.

9. the preparation method of porous nickel alloy electrolysis liberation of hydrogen composite cathode material according to claim 1, it is characterised in that Vacuum in the step (4) in vacuum drying oven is 1 × 10^-2~1 × 10^-3Pa。

10. the system of the porous nickel alloy electrolysis liberation of hydrogen composite cathode material according to any claim in claim 1 to 9 Preparation Method, it is characterised in that C powder used in the step (1) is carbon black, LaNi₅Powder is AB₅Type hydrogen storage alloy.