A supercapacitor positive electrode material and a preparation method thereof

Abstract

The application belongs to the technical field of positive electrode materials of supercapacitors, and discloses a supercapacitor positive electrode material and a preparation method thereof. Based on Co3O4 nanomaterials, the application uses P atoms to enter transition metal crystals to change the performance of the metal and improve the electrochemical performance of the material. A new cobalt oxyphosphide material is prepared through a twice low-temperature calcination method. An electrode sheet is prepared on a foamed nickel substrate. The application makes the supercapacitor have high energy density and power density, and is a successful strategy for improving the electrochemical performance of the supercapacitor. The improvement of the appearance and morphology of the electrode material is one of important factors for improving the electrochemical performance. The application aims to explore the control of the material morphology by reasonable design of the electrode material, and provides a new method for preparing high-capacity energy storage materials by using a low-temperature phosphating method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of positive electrode materials of supercapacitors, and relates to a supercapacitor positive electrode material and a preparation method thereof. BACKGROUND

[0002] Supercapacitors are a new type of environmentally friendly energy storage devices with excellent energy output capacity, long service life, fast charging and discharging speed and other advantages. In recent years, the research on supercapacitors has been continuously strengthened, the related technology industry has developed rapidly, and the market prospect is broad. However, supercapacitors have the defect of low energy density. An effective solution is to research and develop electrode materials with high electrical conductivity and good electrochemical activity. Supercapacitors are an electrochemical device that can be used to store energy, and its working principle is different from that of traditional chemical batteries. According to the basic working principle of storing electric charge, supercapacitors can be divided into double-layer capacitors and pseudo-capacitors. Double-layer capacitors are generated due to the adsorption of anions and cations at the electrode / electrolyte interface. Double-layer capacitors release and store electric charges through a physical process, have high power density, good cycle performance and rate capability, but their energy density is not high. The pseudo-capacitance effect was first proposed by Faraday, which efficiently stores electric energy through rapid oxidation and reduction reactions on the surface of the electrode. The electrode material of the pseudo-capacitor can exhibit higher energy density because of the fast Faraday characteristics.

[0003] Electrode materials are the main influencing factors of the electrochemical performance of supercapacitors. Commonly used supercapacitor electrode materials mainly include three types: carbon-based materials, transition metal compounds (oxides, sulfides, etc.) and conductive polymer materials. These electrode materials all have advantages and disadvantages: carbon-based materials have good cycle stability, simple process and low cost, but low specific capacity; the specific capacity of transition metal compound materials is much higher than that of carbon materials, but the cost is high, the service life is short and there is a certain toxicity; conductive polymer materials have good electronic conductivity, small internal resistance and high specific capacity, but they are prone to volume expansion and shrinkage during the cycle process, and have poor cycle stability. Therefore, developing new electrode materials with multiple advantages is of great significance for the development of supercapacitors. SUMMARY

[0004] Due to the difference in the preparation method, the appearance of the synthesized electrode material will be different, and this factor seriously affects the electrochemical performance of the material. Although the transition metal compound has a very high theoretical specific capacitance, but often due to the appearance of the active site is less, seriously affects its electrochemical energy storage effect, and can not achieve the theoretical effect. The specific application effect is very poor. In order to overcome the deficiencies of the prior art, the present application provides a supercapacitor positive material and a preparation method thereof, specifically a cobalt oxyphosphide supercapacitor electrode material and a preparation method thereof.

[0005] The above object of the application is achieved by the following technical solutions:

[0006] A cobalt oxyphosphide supercapacitor positive material and a preparation method thereof, comprising the following steps:

[0007] Step (1) preparation of ZIF-67 precursor:

[0008] Co(NO3)2·6H2O 0.004-0.006 mol and C4H6N2 0.0046-0.006 mol are dissolved in anhydrous methanol, respectively, and the C4H6N2 solution is added to the pink Co(NO3)2 solution, and the magnetic stirring reaction is carried out for 2-4 h. The centrifuge is used for centrifugal separation for 5-10 minutes to obtain the purple product ZIF-67 precursor, and then washed with distilled water and anhydrous ethanol for 3 times, and dried at 60℃ for 12h, ready for use.

[0009] Step (2) preparation of Co3O4-12:

[0010] The ZIF-67 precursor prepared in step (1) is placed in an electric heating tube furnace, and calcination is carried out in an environment in contact with air. After calcination, it is cooled to room temperature. The dodecahedron Co3O4-12 derived from ZIF-67 is obtained.

[0011] Step (3) preparation of cobalt oxyphosphide material:

[0012] 0.1g of Co3O4-12 and 0.5-1g of sodium hypophosphite are placed in two porcelain boats, respectively, and then they are placed in an electric heating tube furnace, heated at a rate of 5℃·min -1 When the temperature reaches 350℃, keep for 2-4 hours. Cool to room temperature to obtain cobalt oxyphosphide material.

[0013] Further, the magnetic stirring rate of step (1) is 100-300r / min; the centrifuge speed is 4000-10000r / min.

[0014] Further, the calcination temperature in the tube furnace in step (2) is 350-400 DEG C, the temperature rising speed is 5 DEG C / min, and the temperature holding time is 2h.

[0015] Further, the nitrogen flow rate in the nitrogen atmosphere in step (3) is 50-200 mL / min. In the cobalt oxyphosphide electrode material, the approximate atomic ratio of oxygen, phosphorus and cobalt is 3:2:1, and the equivalent diameter is 0.1-0.2 um.

[0016] The electric heating tube furnace is not limited in type.

[0017] The application also claims the application of the positive electrode material prepared by the above preparation method in electrochemistry, specifically, the cobalt oxyphosphide material is uniformly mixed with acetylene carbon black and polytetrafluoroethylene emulsion according to a mass ratio of 8:1:1, and is coated on the nickel foam (NF), and the nickel foam is pressed by a tablet press to obtain a cobalt oxyphosphide / NF electrode.

[0018] The mass of the cobalt oxyphosphide is preferably 0.1-0.15 g, and a cobalt oxyphosphide / NF electrode sheet is obtained, and the specification is 1 cm*1 cm.

[0019] The application is based on Co3O4 nanomaterials, and the P atoms enter the transition metal crystal to change the performance of the metal and improve the electrochemical performance of the material. A new cobalt oxyphosphide material is prepared by a two-time low-temperature calcination method. The electrode sheet is prepared on the nickel foam. Then, the chemical performance of the material is tested by cyclic voltammetry (CV), galvanostatic charge (GCD) and alternating current impedance (EIS). The supercapacitor has high energy density and power density, and is a successful strategy for improving the electrochemical performance of the supercapacitor. The improvement of the appearance of the electrode material is one of the important factors for improving the electrochemical performance. The application aims to explore the control of the material morphology by reasonable design of the electrode material, and provides a new method for preparing high-capacity energy storage materials by low-temperature phosphating.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] (1) The material prepared by the application has a unique honeycomb structure, can provide more active sites in the electrochemical charging and discharging process, and can provide a buffer space to solve the volume expansion of the material in the charging and discharging process.

[0022] (2) The electrode material is reasonably designed to control the material morphology, the P atoms are used to enter the transition metal crystal, the performance of the metal is changed to improve the electrochemical performance of the material. A new cobalt oxyphosphide material is prepared by twice low-temperature calcination at a relatively low temperature (350-400 DEG C). The method is scientific, reasonable, safe and easy to operate, the equipment is simple, the cost is low, the product morphology and structure are controllable, and the method is suitable for batch production of cobalt oxyphosphide electrode material.

[0023] (3) The material CoP2O3 prepared in the application is used as a positive electrode material, and exhibits excellent electrochemical performance in the field of supercapacitors, and has high specific capacitance, excellent cycle stability and small internal resistance. At a current density of 0.5 A·g -1 , the specific capacitance reaches 359.31 F·g -1 ; at a current density of 10 A·g -1 , after 2000 cycles, the material still has a retention rate of 93.81% of the initial specific capacitance; and the equivalent series resistance R s is only 0.66 Ω. The application provides a new idea for the influence of the apparent morphology of the material on the performance of the supercapacitor electrode and the design and development of high-performance supercapacitors. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a schematic diagram for preparation of CoP2O3 in the application.

[0025] Figure 2 It is a part interval electron scanning microscope (SEM) diagram of the material prepared in example 1 of the application. Among them Figure 2 (a) and (b) are SEM diagrams of Co3O4-12 at magnifications of 10,000 times and 21,000 times. Figure 2 (c) and (d) are SEM diagrams of CoP2O3 at magnifications of 10,000 times and 30,000 times.

[0026] Figure 3 It is an element surface distribution diagram of the CoP2O3 material prepared in example 1 of the application. Among them, figure (a) is a mapping diagram of CoP2O3; figure (b) is a C element distribution diagram; figure (c) is a Co element distribution diagram; and figure (d) is a P element distribution diagram.

[0027] Figure 4 It is an X-ray powder diffraction diagram of the Co3O4-12 and CoP2O3 materials prepared in example 1 of the application.

[0028] Figure 5The application performance electrochemical test results of the CoP2O3 material prepared in Example 1 of the present application are shown in the following figures: (a) CV figures at different voltages; (b) CV figures at different scan rates; (c) GCD figures at different current densities; (d) specific capacitance comparison figures at different current densities; (e) EIS figures; (f) capacitance retention rate figures after 2000 charge and discharge cycles. DETAILED DESCRIPTION

[0029] The present application will be described in detail below through specific examples, but the protection scope of the present application is not limited. Unless otherwise specified, the experimental methods used in the present application are conventional methods, and the experimental apparatus, materials, reagents, etc. used can be obtained from commercial channels.

[0030] Example 1

[0031] A cobalt oxyphosphide supercapacitor electrode material and a preparation method thereof, specifically comprising the following steps:

[0032] (1) Preparation of ZIF-67 precursor:

[0033] 1.164g of Co(NO3)2·6H2O and 1.310g of C4H6N2 were respectively dissolved in 50mL of anhydrous methanol, and when the solution became transparent, the C4H6N2 solution was added to the pink Co(NO3)2 solution, and the reaction was magnetically stirred for 2h. Centrifugal separation was performed for five minutes using a centrifuge to obtain a purple product ZIF-67 precursor, which was then washed three times with distilled water and anhydrous ethanol, and dried at 60℃ for 12h for standby use.

[0034] (2) Preparation of Co3O4-12:

[0035] The prepared ZIF-67 precursor was placed in an electric heating tube furnace and calcined in an environment in contact with air. Heating was performed at a rate of 5℃·min -1 , and after reaching 350℃, the temperature was kept constant for 2 hours, and then cooled to room temperature. In this way, dodecahedral Co3O4-12 derived from ZIF-67 was obtained.

[0036] (3) Preparation of CoP2O3 material:

[0037] 0.1g of Co3O4-12 and 0.8g of sodium hypophosphite were respectively placed in two porcelain boats, which were then placed in an electric heating tube furnace and heated at a rate of 5℃·min -1 in a nitrogen atmosphere. When the temperature reached 350℃, it was kept constant for 4 hours. After cooling to room temperature, a cobalt oxyphosphide material was obtained, which is expressed as CoP2O3 according to the approximate atomic ratio of each element. The entire material preparation process is shown in Figure 1 .

[0038] The morphology of Co3O4-12 and CoP2O3 materials obtained using SEM is shown in Figure 2 Figure 2 (a) and (b) are the morphology of Co3O4 crystal particles at magnifications of 10,000 times and 21,000 times, respectively, and it can be seen that the crystals are well-distributed and have a dodecahedron structure. Figure 2 (c) and (d) are the morphology of CoP2O3 crystal particles obtained by low-temperature calcination of Co3O4-12 crystal particles, at magnifications of 10,000 times and 30,000 times, respectively. Although regular octahedrons cannot be seen, it can be roughly seen that the shape is a column with upper and lower bases and six sides. The octahedral particle shape of CoP2O3 is deformed due to partial collapse after phosphating, and the surface area increases. It can be seen that the uniformity is good, and the aggregated shape of multiple crystals is similar to a honeycomb.

[0039] Figure 3 The elemental surface distribution map of the CoP2O3 material is shown in Figure 3 (a) is a Mapping overall map of the CoP2O3 material sample, indicating the structure of the CoP2O3 material and the uniform distribution between different nanoparticles. Figure 3 (b) shows that the base of the material is C element. Figure 3 (c) and (d) show that the Co element and P element are distributed substantially uniformly in the CoP2O3 material.

[0040] The XRD of the Co3O4-12 nanomaterial and the CoP2O3 material synthesized by phosphating the Co3O4-12 nanomaterial are shown in Figure 4 The diffraction peaks at 2θ = 19°, 31.27°, 36.85°, 44.81°, 55.66°, 59.36°, and 65.24° correspond to the diffraction peaks of the product before phosphating, which can be attributed to the (111), (220), (311), (400), (422), (511), and (440) crystal planes of Co3O4-12. After phosphating, a diffraction peak appears at 47.12°, which corresponds to the (400) crystal plane of CoP2O3. It can be seen from the figure that the Co3O4-12 nanomaterial has good crystallinity.

[0041] Comparative Example 1

[0042] A cobalt oxyphosphide supercapacitor electrode material and a preparation method thereof, specifically comprising the following steps:

[0043] (1) Preparation of ZIF-67 precursor:

[0044] ​1.171 g of Co(NO3)2·6H2O and 1.313 g of C4H6N2 were dissolved in 50 mL of anhydrous methanol respectively. When the solutions became clear, the C4H6N2 solution was added to the pink Co(NO3)2 solution, and the mixture was magnetically stirred for 3 h. The product was then centrifuged for five minutes to obtain the purple ZIF-67 precursor, which was then washed three times each with distilled water and anhydrous ethanol, and dried at 80 °C for 12 h for later use.

[0045] (2) Preparation of Co3O4-12:

[0046] The prepared ZIF-67 precursor was placed in an electrically heated tube furnace and calcined in an environment with contact with air. The calcination temperature was 5 °C / min. -1 The mixture was heated at a rate that was maintained at 360°C for 2 hours, and then cooled to room temperature. This yielded a dodecahedral Co3O4-12 derived from ZIF-67.

[0047] (3) Preparation of cobalt oxyphosphide materials:

[0048] 0.1 g of Co3O4-12 and 0.5 g of sodium hypophosphite were placed in two separate porcelain boats, which were then placed in an electrically heated tube furnace and heated at 5 °C / min under a nitrogen atmosphere. -1 The mixture was heated at a rate of [missing information]. Once the temperature reached 360°C, it was held for 2 hours. After cooling to room temperature, cobalt oxyphosphide material was obtained, denoted as CoPO3 based on its atomic ratio.

[0049] Comparative Example 2

[0050] A cobalt oxide supercapacitor electrode material and its preparation method, specifically including the following steps:

[0051] (1) Preparation of ZIF-67 precursor:

[0052] 1.164 g of Co(NO3)2·6H2O and 1.310 g of C4H6N2 were dissolved in 50 mL of anhydrous methanol respectively. When the solutions became clear, the C4H6N2 solution was added to the pink Co(NO3)2 solution, and the mixture was magnetically stirred for 3 h. The product was then centrifuged for five minutes to obtain the purple ZIF-67 precursor, which was then washed three times each with distilled water and anhydrous ethanol, and dried at 80 °C for 12 h for later use.

[0053] (2) Preparation of Co3O4-12:

[0054] The prepared ZIF-67 precursor was placed in an electrically heated tube furnace and calcined in an environment with contact with air. The calcination temperature was 5 °C / min. -1heated at a speed of 5 ℃ / min, and kept constant temperature for 2 hours after reaching 350 ℃, and then cooled to room temperature. In this way, the dodecahedral Co3O4-12 derived from ZIF-67 was obtained.

[0055] Example 1

[0056] The CoP2O3 material prepared in Example 1 was mixed with acetylene carbon black and polytetrafluoroethylene emulsion in a mass ratio of 8:1:1, and uniformly coated on the foamed nickel. The foamed nickel was pressed by a tablet press at 7 MPa for 2 minutes. A cobalt oxy(phosphide) foamed nickel electrode sheet was obtained.

[0057] The prepared cobalt oxy(phosphide) foamed nickel electrode sheet was used as the working electrode, and a platinum metal sheet and a mercury-mercury oxide electrode were used as the counter electrode and the reference electrode, respectively. A three-electrode system was assembled with 6 mol / L KOH as the electrolyte, and cyclic voltammetry and constant current charge-discharge experiments were carried out. The specific capacitance C under different current densities was calculated according to formula (1), and a cycle stability experiment was carried out to detect the electrochemical performance of the material.

[0058] C = IΔt / mΔV Formula (1)

[0059] Wherein, I is the discharge current (A), Δt is the discharge time (s), ΔV is the voltage range (V), and m is the mass of the active material (g).

[0060] The size of the platinum metal sheet electrode was 2 cm x 2 cm; the cyclic voltammetry potential interval was 0.0-0.5 V; and the constant current charge-discharge potential interval was 0.1-0.5 V.

[0061] Comparative Example 1

[0062] The CoPO3 material prepared in Comparative Example 1 was mixed with acetylene carbon black and polytetrafluoroethylene emulsion in a mass ratio of 8:1:1, and uniformly coated on the foamed nickel. The foamed nickel was pressed by a tablet press at 7 MPa for 2 minutes. A cobalt oxy(phosphide) foamed nickel electrode sheet was obtained.

[0063] The rest was the same as in Example 1.

[0064] Comparative Example 2

[0065] The Co3O4-12 material prepared in Comparative Example 2 was mixed with acetylene carbon black and polytetrafluoroethylene emulsion in a mass ratio of 8:1:1, and uniformly coated on the foamed nickel. The foamed nickel was pressed by a tablet press at 7 MPa for 2 minutes. A cobalt oxy(phosphide) foamed nickel electrode sheet was obtained.

[0066] The rest was the same as in Example 1.

[0067] The corresponding three materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 were respectively used as working electrodes for electrochemical tests in Application Example 1 and Application Comparative Example 1 and Application Comparative Example 2, and the results are shown in Table 1.

[0068] Table 1. Electrochemical test results table

[0069]

[0070] As can be seen from Table 1, the CoP2O3 prepared in Example 1 has the best electrochemical performance, with the highest specific capacitance and the smallest equivalent series resistance, indicating that the electrochemical energy storage performance of the fully phosphated material is greatly improved.

[0071] The CoP2O3 material prepared in Example 1 was subjected to more detailed electrochemical tests, and an asymmetric supercapacitor was assembled with CoP2O3 / NF as the positive electrode and commercial activated carbon (AC) as the negative electrode, and a two-electrode electrochemical test was performed with 6 mol / L KOH as the electrolyte.

[0072] The energy density and power density calculation methods are as follows:

[0073] E = C (△V) 2 / 7.2 Formula (2)

[0074] P = 3600E / △t Formula (3)

[0075] Where E is the energy density (W h / kg), △t is the discharge time (s), P represents the power density (W / kg), △V is the charge and discharge voltage interval (V), and C is the specific capacitance value C.

[0076] The CV curves of the CoP2O3 material at different voltages are shown in Figures Figure 5 (a). The results show that in the voltage range of 0.0-0.55V, the area of the CV curve is the largest, but the tail of the curve peak is too sharp, so the test voltage interval is selected as 0.0-0.5V. Figure 5 (b) CV curve shows that CoP2O3 / NF exhibits pseudo-capacitance and double capacitance characteristics, mainly showing double capacitance characteristics, and the pseudo-capacitance characteristics are not obvious, so the redox peaks in the figure are not obvious. Figure 5 (c) GCD curves of CoP2O3 / NF material at different scan rates. At current densities of 0.5 A·g -1 , 1 A·g -1 , 2 A·g -1 , 5 A·g -1 and 10 A·g -1 , the specific capacitances are 359.31 F·g -1 , 320.24 F·g -1277.32F·g -1 240.57 F·g -1 and 209.78 F·g -1 . Figure 5 (d) shows a comparison of the specific capacitance of CoP2O3 / NF at different current densities. It can be seen that as the current density increases from 0.5 to 10 A·g... -1 At that time, its specific capacitance retention rate reached 58.4%. This indicates that the electrode has good rate performance. Compared with Co3O4-12, CoP2O3 / NF showed significantly improved specific capacitance values ​​at different current densities and exhibited better rate performance, indicating that the electrochemical energy storage performance of the phosphating material was greatly improved. Electrochemical impedance spectroscopy (EIS) was used to characterize the CoP2O3 / NF material, revealing the ion transport rate and charge diffusion transport kinetics on the electrode surface in the frequency range of 0.01–10. 5 Hz. Figure 5 (e) The semicircle diameter and the slope of the straight line reflect the conductivity of the material and the contact between CoP2O3 and the NF current collector, respectively. The AC impedance data were simulated using ZSimpWin 3.60 software, and an equivalent circuit model (inner figure) was obtained. As can be seen from the figure, the curve formed by the simulated data and the measured original data are in excellent agreement. This equivalent circuit model is derived from R... s W, R ct It consists of five parts: R, C, and Q. s R represents the sum of contact resistance and the internal resistance of the electrode material, where W is the Warburg impedance and R is the resistance of the electrode material. ct This represents the obstruction to the movement of ions in the electrode channels and electrolyte. C and Q represent capacitance and the constant phase angle element during charging and discharging, respectively. The equivalent series resistance R in the high-frequency region... s The equivalent series resistance is 0.66Ω, R. s This represents the resistance encountered when charge is transferred between the active material and the electrolyte. Figure 5 (f) is the cycle lifetime plot of CoP2O3 / NF, which shows the cycling lifetime at 10 A·g -1 At current density, after 2000 cycles, the material still retains 93.81% of its initial specific capacitance.

[0077] A dual-electrode electrochemical test was conducted on an asymmetric supercapacitor, CoP₂O₃ / NF / / AC / NF, with a potential range of 0–1.5 V and a power density of 369.09 W·kg⁻¹. -1 At that time, the energy density of the CoP2O3 / NF / / AC / NF can reach 24.66 Wh·kg. -1 .

[0078] The above-described embodiments are merely preferred embodiments of the present application, but are not all the embodiments that can be implemented by the present application. Any obvious modifications made by those skilled in the art to the present application without departing from the principles and spirit of the present application should be considered to fall within the scope of protection of the claims of the present application.

Claims

1. A method for preparing cobalt oxyphosphide supercapacitor cathode material, characterized in that, Includes the following steps: Step (1) Preparation of ZIF-67 precursor: Co(NO3)2·6H2O and C4H6N2 were dissolved in anhydrous methanol, and the C4H6N2 solution was added to the pink Co(NO3)2 solution. The mixture was magnetically stirred for 2-4 h. The purple product ZIF-67 precursor was obtained by centrifugation for 5-10 minutes. The precursor was then washed with distilled water and anhydrous ethanol, dried, and set aside for later use. Step (2) Preparation of Co3O4-12: The ZIF-67 precursor prepared in step (1) was placed in an electrically heated tube furnace and calcined in an environment in contact with air; after calcination, it was cooled to room temperature; dodecahedral Co3O4-12 derived from ZIF-67 was obtained. Step (3) Preparation of cobalt oxyphosphide material: 0.1 g of Co3O4-12 and 0.5–1 g of sodium hypophosphite were placed in two separate porcelain boats, which were then placed in an electrically heated tube furnace and heated at 5 °C·min under a nitrogen atmosphere. -1 Heating at a rate of 350 °C; maintaining the temperature for 2-4 hours after reaching 350 °C; cooling to room temperature to obtain cobalt oxyphosphide CoP2O3 material.

2. The method for preparing cobalt oxyphosphide supercapacitor cathode material as described in claim 1, characterized in that, The magnetic stirring speed in step (1) is 100~300r / min.

3. The method for preparing cobalt oxyphosphide supercapacitor cathode material as described in claim 1, characterized in that, Centrifuge speed: 4000~10000 r / min.

4. The method for preparing cobalt oxyphosphide supercapacitor cathode material as described in claim 1, characterized in that, In step (2), the calcination conditions in the tubular furnace are 350~400℃, heating rate: 5℃ / min, and holding time: 2h.

5. The method for preparing cobalt oxyphosphide supercapacitor cathode material as described in claim 1, characterized in that, In step (3), the nitrogen flow rate in the nitrogen atmosphere is 50-200 mL / min.

6. The method for preparing cobalt oxyphosphide supercapacitor cathode material as described in claim 1, characterized in that, In step (1), the product is washed three times each with distilled water and anhydrous ethanol, and then dried at 60 °C for 12 h.

7. The electrochemical application of the cathode material prepared by the method for preparing cobalt oxyphosphide supercapacitor cathode material as described in any one of claims 1-6.

8. The application as described in claim 7, characterized in that, Specifically, cobalt oxyphosphide material is mixed with acetylene black and polytetrafluoroethylene emulsion in a mass ratio of 8:1:1 and uniformly coated on nickel foam. The nickel foam is then pressed into tablets using a tablet press to obtain the cobalt oxyphosphide / NF electrode.

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