Method for producing a porous structured nickel phosphide@carbon anode material and its use

Abstract

Method for producing a porous structured nickel phosphide@carbon anode material, comprising the following steps: S1: Mixing a nickel salt solution with a precipitating agent for reaction, introducing carbon dioxide gas to adjust the pH of the reaction to 10.8 to 11.5, and carrying out aging after completion of the reaction and carrying out solid-liquid separation to obtain a precipitate; wherein the precipitating agent is a mixed solution of sodium hydroxide, sodium tetrahydroxyaluminate, and sodium persulfate; wherein the concentration of the nickel salt solution is 1 mol / L to 2 mol / L; in the precipitating agent, a concentration of sodium tetrahydroxyaluminate is 0.05 mol / L to 0.2 mol / L, a concentration of sodium hydroxide of 3 mol / L to 6 mol / L, a concentration of sodium persulfate of 1 mol / L to 2 mol / L; and mixing is carried out by parallel addition of the nickel salt solution and the precipitating agent, and a flow rate of the nickel salt solution and a flow rate of the precipitating agent are controlled such that a molar ratio of nickel to aluminum is 10:1-2; . S2: Introducing the precipitate into a lower nozzle of a tube furnace, introducing anhydrous sodium hypophosphite into an upper nozzle of the tube furnace, heating the tube furnace for a specific period of time, removing the reaction product and immersing the reaction product in a sodium hydroxide solution and carrying out a solid-liquid separation to obtain porous nickel phosphide; S3: Mixing the porous nickel phosphide with an organic substance and carrying out a carbonization reaction under the condition that oxygen is isolated to obtain the porous structured nickel phosphide@carbon anode material.

Description

TECHNICAL FIELD

[0001] The examples of the present application relate to the technical field of negative electrode materials of lithium-ion / sodium-ion batteries, in particular to a method for producing a porous structured nickel phosphide@carbon anode material and its use. BACKGROUND

[0002] Lithium-ion / sodium-ion batteries have been used as a new type of alternative energy due to their comprehensive performance advantages such as high energy density, high voltage, and long cycle life. Currently, the anode material used on the market is mainly graphite carbon, but due to its poor properties, it is unable to meet the growing demand for high-efficiency lithium-ion / sodium-ion batteries. It is urgently necessary to find an anode material with higher capacity and better stability to further improve the performance of lithium-ion / sodium-ion batteries. Transition metal phosphide and sulfide have much higher theoretical capacities than graphite carbon, suitable voltage platforms, and environmental friendliness, making them very ideal anode materials for lithium-ion / sodium-ion batteries.

[0003] The transition metal phosphide has attracted the interest of researchers due to its important applications in magnetic refrigeration, catalytic desulfurization and hydrogenation of petroleum, and other industrial fields. Furthermore, the transition metal phosphide is an ideal choice for a novel anode material for lithium-ion / sodium-ion batteries due to its stable cycle reversibility, high theoretical specific capacity during charge and discharge, and better safety performance. For example, Ni3P, NiP2, and NiP3, which are rich in phosphorus, have been used as anode materials for lithium-ion batteries. Some researchers have used the hydrothermal microemulsion method to prepare hexagonal Ni2P and tetragonal Ni 12P5, but the particles prepared by this method have poor dispersion, large size, poor conductivity, uncontrollable morphology and structure, etc., and the battery experiences severe volume expansion during charge / discharge cycles, which seriously affects its electrochemical and cyclic performance.

[0004] CN113725426 A discloses a manufacturing process for a Ni(OH) 2- A Ni2P@carbon fabric composite material comprising the steps of: mixing a carbon fabric, a nickel salt solution, and a reducing agent for a hydrothermal reaction to obtain a precursor of a Ni2P@carbon fabric; then subjecting the precursor and the hypophosphite to a high-temperature annealing reaction in a tube furnace under a protective atmosphere to obtain a Ni2 P@carbon fabric to form.

[0005] Transition metal phosphide has attracted considerable attention as an anode material for novel high-performance ion batteries due to its high theoretical capacity and abundant resources. However, when metal phosphide is used as the anode material for ion secondary batteries, it exhibits obvious volume expansion and contraction during ion insertion and removal, resulting in rapid capacity decay and poor rate performance. SUMMARY

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] The examples of the present application aim to solve at least one of the above-mentioned technical problems of the prior art. To this end, the examples of the present disclosure provide a method for producing a porous structured nickel phosphide-carbon anode material and its use.

[0008] According to one aspect of the present application, a method for producing a porous structured nickel phosphide@carbon anode material is provided, comprising the following steps: S1: Mixing a nickel salt solution with a precipitating agent for the reaction, introducing carbon dioxide gas to adjust the pH of the reaction to 10.8 to 11.5, and performing aging after completion of the reaction and performing solid-liquid separation to obtain a precipitate; wherein the precipitating agent is a mixed solution of sodium hydroxide, sodium tetrahydroxyaluminate, and sodium persulfate, the concentration of the nickel salt solution being 1 mol / L to 2 mol / L; in the precipitating agent, a concentration of the sodium tetrahydroxyaluminate is 0.05 mol / L to 0.2 mol / L, a concentration of sodium hydroxide is 3 mol / L to 6 mol / L, a concentration of sodium persulfate is 1 mol / L to 2 mol / L; and mixing is carried out by adding the nickel salt solution and the precipitant in parallel, and a flow rate of the nickel salt solution and a flow rate of the precipitant are controlled so that a molar ratio of nickel and aluminum is 10:1-2;. S2: Introducing the precipitate into a lower nozzle of a tube furnace, introducing anhydrous sodium hypophosphite into an upper nozzle of the tube furnace, heating the tube furnace for a certain period of time, taking out the reaction product and immersing the reaction product in a sodium hydroxide solution, and performing solid-liquid separation to obtain porous nickel phosphide; S3: Mixing the porous nickel phosphide with an organic substance and conducting a carbonization reaction under the condition of isolating oxygen to obtain the porous structured nickel phosphide@carbon anode material.

[0009] In some embodiments of the present application, the nickel salt solution in step S1 is at least one of the following: a nickel sulfate solution, a nickel chloride solution, or a nickel nitrate solution.

[0010] In some embodiments of the present application, the method in step S1, after the precipitate is obtained by solid-liquid separation, further comprises washing and drying the precipitate.

[0011] In some embodiments of the present application, in step S1, the aging is performed for 1 h to 2 h.

[0012] In some embodiments of the present application, in step S2, the mass ratio of the anhydrous sodium hypophosphite to the precipitate is (8-15): 1.

[0013] In some embodiments of the present application, in step S2, the tube furnace is heated to a temperature of 300°C to 400°C, and the heating of the tube furnace takes place for 120 minutes to 180 minutes. The heating rate of the tube furnace is 2°C / min to 5°C / min.

[0014] In some embodiments of the present application, the reaction product in step S2 is first cooled to 10°C or below after withdrawal, and the temperature of the sodium hydroxide solution is 2°C to 8°C.

[0015] In some embodiments of the present application, in step S2, the concentration of the sodium hydroxide solution is 0.1 mol / L to 2 mol / L, and the immersion is carried out for 10 minutes to 25 minutes.

[0016] In some embodiments of the present application, in step S3, the organic substance is at least one of sucrose, glucose or lactose.

[0017] In some embodiments of the present application, in step S3, the carbonization is carried out at a temperature of 500°C to 800°C for 1h to 12h.

[0018] The present disclosure further provides the use of a nickel phosphide@carbon anode material prepared by the above methods in a sodium-ion battery or a lithium-ion battery.

[0019] According to a preferred embodiment of the present application, the present application has at least the following advantageous effects. 1. In examples of the present application, aluminum-doped nickel oxide hydroxide is first prepared, and then the aluminum-doped nickel oxide hydroxide is reacted with sodium hypophosphite to obtain nickel aluminum phosphide. The nickel aluminum phosphide is immersed in cold sodium hydroxide to obtain a porous nickel phosphide anode material. After further carbonization, the target product, a porous nickel phosphide carbon anode material, is obtained. 2. In the production of aluminum-doped nickel oxide hydroxide, sodium hydroxide and sodium persulfate are mixed with sodium tetrahydroxyaluminate. On the one hand, nickel oxide hydroxide is produced directly, and on the other hand, aluminum is coprecipitated in the form of aluminum hydroxide to achieve atomic mixing of nickel and aluminum. The reaction equations are as follows: 2Ni2++S2Q8 2 -+6OH-=2NiOOH+2SO4 2- +2H2O; 2[Al(OH)4] - +CO2= 2 Al(OH)3+CO3 2- +H2O. 3. The sodium hypophosphite is heated to generate phosphine. The phosphine reacts with the aluminum-doped nickel oxide hydroxide to produce nickel-aluminum phosphide. Taking advantage of the high solubility of aluminum phosphide, the nickel-aluminum phosphide was immersed in cold sodium hydroxide solution to remove aluminum, thus freeing atomic vacancies around the nickel atoms, which benefits the volume expansion of the anode material during the charge-discharge reaction. The reaction equations are as follows: 5NaH2PO2=2PH3+2H2+ Na4P2O7+NaPO3; 4NiOOH+3H2+2PH3=2Ni2P+8H2O; Al(OH)3+PH3=AlP+3H2O; AlP+NaOH+3H2O=Na[Al(OH)4]+PH3. 4. The anode material prepared by examples of the present application is nanoscale, with a particle size of 10 nm to 100 nm, and has a porous structure. During the charging and discharging process, its internal porous structure can not only buffer the volume change caused by the charging and discharging process, but also increase the contact area between the electrode and the electrolyte, and has high capacity, excellent cycling and rate performance. Furthermore, the carbonization treatment forms a supporting carbon skeleton structure inside and outside the particles, further improving the strength and conductivity of the particles.

[0020] After reading and understanding the drawings and the detailed description, further aspects can be understood. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings are intended to facilitate understanding of the technical solutions of the present disclosure and are part of the specification. Together with the examples, they serve to explain the technical solutions of the disclosure, which do not limit the technical solutions of the disclosure.

[0022] The present application is described in more detail below in conjunction with the drawings and examples. Fig. Figure 1 is a scanning electron micrograph of a porous structured nickel phosphide-carbon anode material prepared according to Example 1 of the present application. DETAILED DESCRIPTION

[0023] The concept and technical effects of the present application are described clearly and completely in conjunction with the examples so that the purpose, features, and effects of the present application are fully understood. Of course, the examples described are only a portion of the examples of the present application and not all of them. Starting from the examples of the present application, other examples found by those skilled in the art without creative effort fall within the scope of the present application. Example 1

[0024] In this example, a porous nickel phosphide@carbon anode material was prepared. The specific processes were as follows. (1) A nickel sulfate solution of 1 mol / L was prepared. (2) A precipitant was prepared. The precipitant was a mixed solution of sodium hydroxide, sodium tetrahydroxyaluminate, and sodium persulfate, with the concentration of sodium tetrahydroxyaluminate being 0.05 mol / L, the concentration of sodium hydroxide being 3 mol / L, and the concentration of sodium persulfate being 1 mol / L. (3) The nickel sulfate solution and the precipitant were added in parallel to a reactor, carbon dioxide gas was introduced to adjust the reaction pH to 11.5, and the flow rate of the nickel salt solution and the flow rate of the precipitant were controlled so that the molar ratio of nickel and aluminum was 10:2. (4) After completion of the reaction, aging was carried out for 1 hour and solid-liquid separation was carried out to obtain a precipitate. (5) The precipitate was washed and dried and then placed into a lower tuyere of a tube furnace. (6) Anhydrous sodium hypophosphite was added to an upper nozzle of the tube furnace, and the mass ratio of anhydrous sodium hypophosphite to the precipitate was 8:1. (7) The tube furnace was heated to 300°C for 180 minutes at a heating rate of 2°C / min. (8) After completion of the reaction of step (7), the reaction product was taken out, cooled to 10°C or less, and immersed in a sodium hydroxide solution having a temperature of 2°C to 8°C and a concentration of 0.1 mol / L for 25 minutes. (9) After solid-liquid separation, the reaction product was washed with deionized water and dried to obtain porous nickel phosphide. (10) The porous nickel phosphide was mixed with a sucrose solution. Under the condition of oxygen isolation, the resulting mixture was reacted at 500°C for 2 hours to obtain a porous structured nickel phosphide@carbon anode material with a particle size of 10 nm to 100 nm. Example 2

[0025] In this example, a porous nickel phosphide@carbon anode material was prepared. The specific processes were as follows. (1) A nickel chloride solution of 1.5 mol / l was prepared. (2) A precipitant was prepared. The precipitant was a mixed solution of sodium hydroxide, sodium tetrahydroxyaluminate, and sodium persulfate, with the concentration of sodium tetrahydroxyaluminate being 0.1 mol / L, the concentration of sodium hydroxide being 5 mol / L, and the concentration of sodium persulfate being 1.5 mol / L. (3) The nickel chloride solution and the precipitant were added in parallel to a reactor, carbon dioxide gas was introduced to adjust the reaction pH to 11.1, and the flow rate of the nickel salt solution and the flow rate of the precipitant were controlled so that the molar ratio of nickel and aluminum was 10:1. (4) After completion of the reaction, aging was carried out for 1 hour and solid-liquid separation was carried out to obtain a precipitate. (5) The precipitate was washed and dried and then placed into a lower tuyere of a tube furnace. (6) Anhydrous sodium hypophosphite was added to an upper tuyere of the tube furnace, and the mass ratio of anhydrous sodium hypophosphite to the precipitate was 11:1. (7) The tube furnace was heated to 350°C for 150 minutes at a heating rate of 3°C / min. (8) After completion of the reaction of step (7), the reaction product was taken out, cooled to 10°C or less, and immersed in a sodium hydroxide solution with a temperature of 2°C to 8°C and a concentration of 1 mol / L for 15 minutes. (9) After solid-liquid separation, the reaction product was washed with deionized water and dried to obtain porous nickel phosphide. (10) The porous nickel phosphide was mixed with a glucose solution. Under the condition of oxygen isolation, the resulting mixture was reacted at 600°C for 6 hours to obtain a porous structured nickel phosphide@carbon anode material with a particle size of 10 nm to 100 nm. Example 3

[0026] In this example, a porous nickel phosphide@carbon anode material was prepared. The specific processes were as follows. (1) A nickel nitrate solution of 2 mol / L was prepared. (2) A precipitant was prepared. The precipitant was a mixed solution of sodium hydroxide, sodium tetrahydroxyaluminate, and sodium persulfate, with the concentration of sodium tetrahydroxyaluminate being 0.2 mol / L, the concentration of sodium hydroxide being 6 mol / L, and the concentration of sodium persulfate being 2 mol / L. (3) The nickel nitrate solution and the precipitant were added in parallel to a reactor, carbon dioxide gas was introduced to adjust the reaction pH to 10.8, and the flow rate of the nickel salt solution and the flow rate of the precipitant were controlled so that the molar ratio of nickel and aluminum was 10:1. (4) After completion of the reaction, aging was carried out for 2 hours and solid-liquid separation was performed to obtain a precipitate. (5) The precipitate was washed and dried and then placed into a lower tuyere of a tube furnace. (6) Anhydrous sodium hypophosphite was attached to an upper nozzle of the tube furnace, and the mass ratio of anhydrous sodium hypophosphite to the precipitate was 13:1. (7) The tube furnace was heated to 400°C for 120 minutes at a heating rate of 5°C / min. (8) After completion of the reaction of step (7), the reaction product was taken out, cooled to 10°C or less, and immersed in a sodium hydroxide solution with a temperature of 2°C to 8°C and a concentration of 2 mol / L for 10 minutes. (9) After solid-liquid separation, the reaction product was washed with deionized water and dried to obtain porous nickel phosphide. (10) The porous nickel phosphide was mixed with a glucose solution. Under the condition of oxygen isolation, the resulting mixture was reacted at 800°C for 12 hours to obtain a porous structured nickel phosphide@carbon anode material with a particle size of 10 nm to 100 nm. Comparative example

[0027] In this comparative example, nickel phosphide was prepared by a hydrothermal method, and the specific processes were as follows.

[0028] Nickel nitrate and sodium hypophosphite were mixed to obtain a suspension solution. The suspension solution was stored in a water bath at 60°C for 2 hours and sonicated for 30 minutes. The liquid was poured into a hydrothermal reactor, reacted at 120°C for 12 hours, removed, and allowed to stratify to obtain a black solid. The black solid was washed with deionized water and ethanol solution, filtered, and the filter cake was dried at 60°C to obtain a black nickel phosphide powder (Ni2P). Example of a test

[0029] The anode material obtained in Examples 1 to 3 and the nickel phosphide obtained in Comparative Example were each used to prepare the negative electrode pieces of the lithium-ion battery. The lithium metal plate was used as the positive electrode, and the above-mentioned negative electrode and positive electrode were assembled to form a CR2025 button battery. The test was conducted at a charging and discharging voltage of 0.01 V to 3 V and a current density of 100 mA / g (0.1 C). The results are shown in Table 1. Table 1 Gram capacity after first charge and discharge mAh / g Gram capacity after secondary charge and discharge mAh / g Gram capacity after 100 charges and discharges mAh / g Example 1 988 899 701 Example 2 971 835 683 Example 3 979 856 682 Comparative example 849 726 567

[0030] From Table 1, it can be seen that the electrochemical performances of the examples were significantly better than those of the comparative example, which can be attributed to the porous structure of the anode materials of the examples. During the charging and discharging process, the internal porous structure can not only buffer the volume change caused by the charging and discharging process but also increase the contact area between the electrode and the electrolyte, thereby achieving high capacity and excellent cycling and rate performance. In addition, the anode materials of the examples were also subjected to carbonization treatment, so that a supporting carbon skeleton structure was formed inside and outside the particles, which could further improve the strength and conductivity of the particles.

Claims

[1] A process for producing a porous structured nickel phosphide@carbon anode material, comprising the following steps: S1: Mixing a nickel salt solution with a precipitating agent for reaction, introducing carbon dioxide gas to adjust the reaction pH to 10.8 to 11.5, and performing aging after completion of the reaction and performing solid-liquid separation to obtain a precipitate; wherein the precipitating agent is a mixed solution of sodium hydroxide, sodium tetrahydroxyaluminate, and sodium persulfate; wherein the concentration of the nickel salt solution is 1 mol / L to 2 mol / L; in the precipitating agent, a concentration of the sodium tetrahydroxyaluminate is 0.05 mol / L to 0.2 mol / L, a concentration of sodium hydroxide is 3 mol / L to 6 mol / L, a concentration of sodium persulfate is 1 mol / L to 2 mol / L; and mixing is carried out by adding the nickel salt solution and the precipitant in parallel, and a flow rate of the nickel salt solution and a flow rate of the precipitant are controlled so that a molar ratio of nickel and aluminum is 10:1-2;. S2: Introducing the precipitate into a lower nozzle of a tube furnace, introducing anhydrous sodium hypophosphite into an upper nozzle of the tube furnace, heating the tube furnace for a certain period of time, withdrawing the reaction product and immersing the reaction product in a sodium hydroxide solution, and performing solid-liquid separation to obtain porous nickel phosphide; S3: Mixing the porous nickel phosphide with an organic substance and conducting a carbonization reaction under the condition that oxygen is isolated to obtain the porous structured nickel phosphide@carbon anode material. [2] The method according to claim 1, wherein in step S1, the nickel salt solution is at least one of nickel sulfate solution, nickel chloride solution or nickel nitrate solution. [3] The method according to claim 1, wherein the method further comprises, in step S1, after the precipitate is obtained by solid-liquid separation, washing and drying the precipitate. [4] The process according to claim 1, wherein in step S2 the mass ratio of anhydrous sodium hypophosphite to the precipitate is 8-15:

1. [5] The method according to claim 1, wherein in step S2 the tube furnace is heated to a temperature of 300 °C to 400 °C and the heating is carried out for 120 min to 180 min. [6] The method according to claim 1, wherein in step S2, the reaction product is first cooled to 10°C or below after withdrawal and the temperature of the sodium hydroxide solution is 2°C to 8°C. [7] The method according to claim 1, wherein in step S2, the sodium hydroxide solution has a concentration of 0.1 mol / L to 2 mol / L; and the immersion is carried out for 10 min to 25 min. [8] The method according to claim 1, wherein in step S3 the organic substance is at least one of sucrose, glucose or lactose. [9] Use of the porous structured nickel phosphide@carbon anode material produced according to one of claims 1 to 8 in a sodium ion battery or a lithium ion battery.

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