CN111233054A

CN111233054A - Copper-doped three-dimensional multilevel-structure nickel hydroxide material and preparation method and application thereof

Info

Publication number: CN111233054A
Application number: CN202010064888.0A
Authority: CN
Inventors: 袁斌; 张峻豪; 李少波; 胡仁宗; 朱敏
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2020-01-20
Filing date: 2020-01-20
Publication date: 2020-06-05
Anticipated expiration: 2040-01-20
Also published as: CN111233054B

Abstract

The invention discloses a copper-doped spherical multilevel-structure nickel hydroxide material and preparation and application thereof. The preparation method firstly prepares the NiSO₄Aqueous solution with Na₂S₂O₈Uniformly mixing; then adding concentrated ammonia water into the aqueous solution, uniformly mixing, then adding copper foil, and standing at room temperature for 24-40 h; and after the reaction is finished, centrifugally collecting a reaction product, washing the reaction product with water for several times, and then drying the product in vacuum to obtain the copper-doped spherical multilevel-structure nickel hydroxide material. The preparation method has strong controllability and simple operation, and can be used for lithium ion IIThe large-scale production of the electrode material of the secondary battery can obviously improve the cycle life of the electrode material.

Description

Copper-doped three-dimensional multilevel-structure nickel hydroxide material and preparation method and application thereof

Technical Field

The invention relates to nickel hydroxide (Ni (OH) with a three-dimensional multi-level structure stacked by nano sheets₂) The material, the preparation method and the application belong to the field of nanometer functional materials and lithium ion secondary batteries.

Background

Lithium Ion Batteries (LIBs) are mainly composed of an anode, a cathode, an electrolyte, a diaphragm and the like. Li at charging⁺Extracted from the positive electrode, inserted into the negative electrode, and upon discharge, Li⁺Emerging from the negative electrode and fitting into the positive electrode, which is also known as a "rocking chair battery" because of the characteristics of lithium ion batteries.

The lithium ion battery is favored by researchers due to the advantages of high volume and mass energy density (high specific capacity), high output voltage (working voltage of 3.7V), low self-discharge, long service life and the like. One of the important factors affecting the energy output of lithium ion batteries is the specific capacity and voltage plateau of the positive electrode and the negative electrode, but the graphite negative electrode currently and commercially used is due to its low theoretical specific capacity (372mAh g)^-1) The demand of the times has been gradually unsatisfied, so that materials with higher capacity are required. Among the various alternative anode materials, nickel-based oxides (NiO) and their hydroxides (Ni (OH)₂) Due to its considerable specific capacity (715 mAhg)^-1And 576mAh g^-1) Abundant resources, no toxicity and the like are widely concerned. However, nickel hydroxide cannot be popularized and applied because of its defects, including poor intrinsic conductivity, which causes large volume change during circulation, and finally causes material pulverization and shedding, and capacity rapid decay. The current methods for solving the problems mainly comprise nanocrystallization, multiphase compounding, doping for improving conductivity and structural stability and the like.

The nano-sizing limits the particle size of the material to nano level, which can reduce the absolute volume change of the material during lithium extraction and shorten Li⁺And (6) transferring the path. However, single nanocrystallization can cause material agglomeration, and meanwhile, the area of an SEI film can be increased due to the large specific surface area of the nanomaterial, so that more Li is generated⁺Loss, resulting in a first low coulombic efficiency and, in addition, a low stacking density.

The multiphase compounding means that a composite phase is constructed, an active material is compounded with other materials, a second phase comprises a buffer phase and is equal in conductivity, the improvement of the cycle performance of the battery by the measure is limited, and after a certain cycle number, the electrode material is inevitably pulverized and then loses efficacy.

Doping is also a commonly used method to improve the properties of electrode materials. The performance improvement of the doped material mainly comes from two aspects, namely the improvement of the conductivity and the structural stability. But the single doping measure can only improve the cycle performance of the material to a limited extent.

In summary, neither of the above methods alone can solve Ni (OH)₂The cycle performance and rate capability of the negative electrode material are poor. The reason is that the performance of the anode material can only be improved to a certain extent by using the method alone, and the requirements of the anode material on huge volume change and electrode structural integrity in the long-term circulation process cannot be met.

CN2015101803613 discloses a preparation method of a nickel hydroxide negative electrode material for a lithium ion battery. Dissolving divalent nickel salt with distilled water to prepare a nickel salt solution; dissolving potassium hydroxide or sodium hydroxide with distilled water to prepare an alkali solution of potassium hydroxide or sodium hydroxide; controlling the reaction temperature to be 60 ℃, dropwise adding the alkali solution into the nickel salt solution under the stirring condition, and controlling the pH value of the reaction system to be 11.0; after the reaction is finished, the nickel hydroxide cathode material for the lithium ion battery is obtained after suction filtration, washing and freeze drying. Although the prepared nickel hydroxide has higher capacity, the first discharge capacity is 2237mAh g^-1But at 100mA g^-1Current density of (1) and only 1107mAh g is left after 30 times of circulation^-1The capacity of (a) is poor, the cycle stability is poor, and the life of nickel hydroxide as a negative electrode of a lithium ion battery is not substantially improved.

Disclosure of Invention

In order to overcome Ni (OH)₂The invention aims to provide a preparation method of a copper-doped multilevel-structure nickel hydroxide material, which has the defects of a negative electrode materialCan effectively improve the cycling stability of the nickel hydroxide used as the cathode material in the lithium ion battery.

With NiSO₄Adding copper foil, ammonia water and Na in the reaction system as a nickel source₂S₂O₈Preparing a new material made of Ni (OH)₂The nano-sheets are elementary and can be assembled into Ni (OH) with micron-sized spherical structure₂A material. The material is used as a lithium ion battery cathode material and can reinforce Li⁺And the transmission of electrons, relieve the volume change produced in the charge-discharge process, achieve the goal of improving the capacity, cycle performance and rate performance of the lithium ion battery.

In the invention, copper foil and Na are added into a reaction system₂S₂O₈Can oxidize copper foil into copper ions, the concentration of the copper ions in the solution and Na₂S₂O₈The amount is proportional. Copper ions can be doped as doping ions into the layered Ni (OH)₂In the lithium ion battery, since the ionic radius of copper ions is larger than that of nickel ions, the interlayer spacing of nickel hydroxide can be stabilized and further increased, and Li in the process of lithium intercalation and deintercalation is increased⁺The rate of nickel hydroxide, after second doping with copper, is determined by β -Ni (OH)₂Conversion to α -Ni (OH)₂The latter having a larger interlayer spacing and simultaneously generating α -Ni (OH)₂Is a nano sheet structure and is assembled into a micro spherical structure. The specific surface area of the micron-scale particles is smaller, so that an SEI film is formed less; the nanosheet layer contributes to Li⁺Rapid insertion and extraction of Li and shortening of Li⁺And the transmission distance of electrons, and the pores among the nano-sheet layers are favorable for buffering nano α -Ni (OH)₂The volume change of the lamella enhances the structural stability of the electrode material, and further improves the cycle stability of the electrode material, the multi-level micron spherical α -Ni (OH)₂The material can better meet the requirement of being used as the lithium ion battery cathode material, the preparation process is simple, and the preparation is carried out at room temperature, so that external heating sources, such as hydrothermal conditions and the like, are not needed, the obvious energy-saving effect is achieved, and the large-scale production is more favorably realized.

The purpose of the invention is realized by the following technical scheme:

the preparation method of the copper-doped spherical multilevel-structure nickel hydroxide material comprises the following steps:

(1) mixing NiSO₄Dissolving in deionized water, stirring to obtain solution A, NiSO₄The concentration is 0.5-1 mol/L;

(2) adding Na into the solution A obtained in the step (1) under stirring₂S₂O₈Obtaining a solution B; wherein Na₂S₂O₈With NiSO₄The mass ratio of (A) to (B) is 0.12: 1-0.65: 1;

(3) adding ammonia water into the solution B obtained in the step (2) under stirring to obtain a solution C;

(4) adding excessive copper foil into the solution C obtained in the step (3), standing, and reacting for 24-40 hours at room temperature;

(5) and (4) after the reaction is finished, centrifugally collecting the reaction product obtained in the step (4), washing, and then carrying out vacuum drying on the reaction product to obtain the spherical multilevel-structure nickel hydroxide material.

To further achieve the object of the present invention, it is preferable that NiSO used in step (1) is₄For analytical purification.

Preferably, the stirring in the steps (1), (2) and (3) is magnetic stirring, the rotating speed is 100-400 r/min, and the time is 12-18 min.

Preferably, the concentration of the ammonia water in the step (3) is 25-28%, and the volume of the ammonia water accounts for 8-15% of the volume of the deionized water in the step (1).

Preferably, the amount of the copper foil in the step (4) is Na₂S₂O₈The mass of the copper is 40-100%, and redundant copper can be removed in the cleaning process.

Preferably, the copper foil in the step (4) is pure copper foil of a negative current collector of a commercial lithium ion battery, the thickness is 10 μm, and the purity is more than or equal to 99.8%.

Preferably, the washing in step (5) is washing with water 5 times or more.

Preferably, the vacuum drying in the step (5) is carried out at the temperature of 60-80 ℃, the drying time is 12-24 hours, and the vacuum degree of drying is 1000-4000 Pa.

Copper-doped spherical multilevel junctionThe structural nickel hydroxide material is prepared by the preparation method, and the basic unit of the spherical multilevel structure is made of nano flaky Ni (OH)₂The diameter of the ball is 0.5-3 mu m, and the nano-flake Ni (OH)₂The length and width ranges of the film are respectively 200-700 nm, and the thickness is 5-20 nm.

The spherical multilevel-structure nickel hydroxide material is prepared by doping nickel hydroxide with copper foil as a copper source and is applied to secondary battery electrode materials.

The principle of the invention is as follows: the main function of the added ammonia water is to react with Ni²⁺Forming nickel hydroxide which is capable of precipitating at room temperature without heating to hydrolyze the nickel salt to produce a precipitate, and adding the copper foil in Na₂S₂O₈Can become Cu under strong oxidation²⁺Doping in the nickel hydroxide during its formation, while the copper may consume part of the ammonia, lower the pH of the system, promoted α -Ni (OH)₂Formation (β -Ni (OH) when pH is too high₂) Furthermore, the nickel hydroxide nanosheets formed may stack into spheres as a result of the "directional bonding" growth process.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the invention can be realized by adding Na₂S₂O₈The preparation method is used as an oxidant to realize the preparation of the spherical multilevel copper-doped nickel hydroxide material, and no additional step is needed after the reaction, so that the preparation method has the advantages of simple process, high efficiency and batch production.

(2) The invention can obtain the micron-sized anode material with controllable morphology by a simple one-step coprecipitation method, does not need other measures such as hydrothermal treatment and the like, saves energy and is simple and convenient to operate.

(3) Micron multilevel structure α -Ni (OH) prepared by the invention₂The material is used as the lithium ion battery cathode, can effectively improve the volume expansion caused by long-term circulation, and improves the overall capacity, rate capability and cycle life of the lithium ion battery.

Drawings

FIG. 1 shows the case of example 1 without adding copper foil and Na₂S₂O₈To obtainOriginal β -Ni (OH)₂Sample with copper foil and Na added₂S₂O₈The obtained spherical multilevel structure α -Ni (OH)₂XRD diffractograms of copper-doped nickel hydroxide prepared for the samples and for different amounts of sodium persulfate added in example 2 and example 3.

Also included in the figure are α -Ni (OH)₂(PDF #00-038-0715) and β -Ni (OH)₂(PDF #00-002-1112) standard XRD diffraction spectrum;

FIG. 2 shows the copper-doped spherical multilevel structure α -Ni (OH) of example 1₂And virgin β -Ni (OH) undoped with copper₂Wherein FIGS. 2(a) and 2(b) are SEM images of copper-doped spherical multilevel structure α -Ni (OH) prepared by adding 1.5g of sodium persulfate to the solution of example 1₂SEM images of the sample at 20000 times and 10000 times magnification, respectively, FIG. 2(c) and FIG. 2(d) are original β -Ni (OH) without copper doping₂SEM images of the samples at 20000 and 10000 times magnification, respectively;

FIG. 3 shows copper-doped spherical multilevel α -Ni (OH) prepared by adding 1g (example 2) and 2.5g (example 3) of sodium persulfate respectively₂Wherein FIGS. 3(a) and 3(b) are the copper-doped spherical multilevel structure α -Ni (OH) prepared by adding 1g of sodium persulfate to example 2₂SEM images of sample at 20000 times and 10000 times magnification, respectively, and FIGS. 3(c) and 3(d) are the copper-doped spherical multilevel α -Ni (OH) prepared by adding 2.5g of sodium persulfate to example 3₂SEM images of the samples at 20000 and 10000 times magnification, respectively;

FIG. 4 shows virgin β -Ni (OH) in example 1₂Sample (FIG. 4- (4)) and addition of 1.5g of sodium persulfate produced a copper-doped spherical multilevel structure α -Ni (OH)₂Sample (FIG. 4- (1)) and example 2 with 1g sodium persulfate added (FIG. 4- (2)) and example 3 with 2.5g sodium persulfate added (FIG. 4- (3)) prepare copper-doped spherical multilevel structure α -Ni (OH)₂A graph of the cycling performance of the sample at 1A/g current density for 630 cycles;

FIG. 5 shows β -Ni (OH) as received in example 1₂Sample and copper doped multiple flower α -Ni (OH) prepared with addition of 1.5g sodium persulfate₂Sample and example 2 with 1g sodium persulfate and example 3 with 2.5g perPreparation of copper-doped spherical multilevel Structure from sodium sulfate α -Ni (OH)₂A comparison graph of rate performance of the sample;

FIG. 6 shows the preparation of copper-doped spherical multilevel α -Ni (OH) by adding 1g of sodium persulfate in example 1₂Analyzing each element of the EDX energy spectrum of the sample;

FIG. 7 shows the preparation of copper-doped spherical multilevel α -Ni (OH) by adding 1.5g of sodium persulfate in example 2₂Analyzing each element of the EDX energy spectrum of the sample;

FIG. 8 shows the preparation of copper-doped spherical multilevel α -Ni (OH) by adding 2.5g of sodium persulfate in example 3₂And (3) analyzing each element of the EDX energy spectrum of the sample.

Detailed Description

For a better understanding of the present invention, the present invention will be further described with reference to the following examples and drawings, but the present invention is not limited thereto.

Example 1

(1) Will analyze pure NiSO₄(6.8g) dissolved in deionized water (50mL) and magnetically stirred at 200 rpm for 15 minutes to give solution A;

(2) adding Na into the solution A obtained in the step (1) under magnetic stirring₂S₂O₈(1.5g), stirring for 15 minutes to give solution B;

(3) under magnetic stirring, adding 5ml of concentrated ammonia water (25-28%) into the solution B obtained in the step (2), and stirring for 15 minutes to obtain a solution C;

(4) and (4) adding 1g of commercial lithium ion battery negative copper foil into the solution C obtained in the step (3), wherein the thickness is 10 microns, the purity is more than or equal to 99.8 percent, and standing for 24 hours at room temperature.

(5) After the reaction is finished, the reaction product obtained in the step (4) is collected by centrifugation and washed for 6 times by water, and then the reaction product is dried for 24 hours in vacuum at 60 ℃ under the vacuum degree of 1000 Pa.

The XRD diffraction pattern of the reaction product is shown in figure 1- (2), and the generated Ni (OH) is doped₂α -Ni (OH) with hexagonal structure₂Without addition of copper foil and Na₂S₂O₈The product of (A) is β -Ni (OH) of hexagonal structure₂XRD results thereof correspond toFIG. 1- (1), due to the consumption of a portion of ammonia by the added copper foil, the lowering of the available pH (favoured by the formation of α -Ni (OH))₂) Meanwhile, because the ionic radius (73pm) of copper is larger than that (69pm) of nickel ions, after successful doping, the interlayer distance of the material is increased to form α -Ni (OH)₂The basic unit of the reaction product is a nano-sheet structure, as shown in SEM image 2(a) at 20000 times, and each nano-sheet layer is assembled into a multi-stage spherical structure of 0.5 to 3 μm size, as shown in SEM image 2(b) at 10000 times, from which it is known that copper-doped α -Ni (OH) is prepared by adding 1.5g of sodium persulfate₂The two obtained samples are subjected to energy spectrum analysis, and according to data in a table 1 in a figure 6, the samples prepared from 1g of sodium persulfate contain Ni, Cu, S and O, wherein the mass percent of the doped copper is 11.85%.

TABLE 1

Kind of element	Atomic number	Characteristic X-ray	Mass percent of elements	Atomic percent of element
					Ni	28	K layer release of X-rays	49.95	26.11
O	8	K layer release of X-rays	32.89	63.08
					Cu	29	K layer release of X-rays	11.85	5.72
S	16	K layer release of X-rays	5.31	5.08

In a glove box to prepare a resulting spherical multilevel structure α -Ni (OH)₂The prepared half cell is subjected to charge and discharge performance test in a blue cell test system, wherein the specific parameters comprise that the current density is 1A/g, the charge and discharge voltage range is 0.01V-3V, as can be seen from a line (1) in figure 4, the first discharge capacity reaches 1715.6mAh/g, the specific capacity after 630 cycles can be kept at 1287.4mAh/g, and the capacity retention rate is about 75 percent, however, for the prepared original β -Ni (OH)₂(FIG. 4- (4)), the first discharge capacity was 1292.8mAh/g, but the specific capacity after 630 cycles was reduced to 391.3mAh/g, and the capacity retention rate was only about 30%. In addition, the rate performance curve (FIG. 5) can be seenIt is seen that from the current density of 100mA/g to 2000mA/g and then back to 100mA/g, the product after doping has more excellent rate performance.

Example 2

(1) Will analyze pure NiSO₄(7.75g) dissolved in deionized water (50mL) and magnetically stirred at 400 rpm for 18 minutes to give solution A;

(2) adding Na into the solution A obtained in the step (1) under magnetic stirring₂S₂O₈(1g) Stirring for 18 minutes to obtain a solution B;

(3) under magnetic stirring, adding 5ml of concentrated ammonia water (25-28%) into the solution B obtained in the step (2), and stirring for 18 minutes to obtain a solution C;

(4) and (4) adding 1g of commercial lithium ion battery negative copper foil into the solution C obtained in the step (3), wherein the thickness is 10 microns, the purity is more than or equal to 99.8 percent, and standing for 40 hours at room temperature.

(5) After the reaction is finished, the reaction product obtained in the step (4) is collected by centrifugation and washed by water for 8 times, and then the reaction product is dried for 12 hours in vacuum at 80 ℃ under the vacuum degree of 4000 Pa.

The reaction product is α -Ni (OH) also in hexagonal structure₂The XRD result corresponds to line (3) in fig. 1, the basic unit of the reaction product is a nano-platelet structure, and the individual nano-platelets assemble into a multi-level spherical structure of 0.5-3 μm size, as shown in fig. 3(a) and 3(b), which are SEM images at 20000 times and 10000 times magnification, respectively. The figure shows the appearance of the sample prepared by adding 1g of sodium persulfate, and more gaps exist among the sheet layers, which is favorable for relieving volume expansion, wherein the sheet Ni (OH)₂The length and width ranges of the film are respectively 200-700 nm, and the thickness is 10-20 nm. When the material prepared by adding 1g of sodium persulfate was subjected to energy spectrum analysis, it was found from the data shown in FIG. 7 and Table 2 below that a sample prepared by adding 2g of sodium persulfate had Ni, Cu, S and O, and the percentage by mass of copper incorporated therein was 15.56%.

TABLE 2

Kind of element	Atomic number	Characteristic X-ray	Mass percent of elements	Atomic percent of element
					Ni	28	K layer release of X-rays	46.07	24.01
O	8	K layer release of X-rays	33.31	63.68
					Cu	29	K layer release of X-rays	15.56	7.49
S	16	K layer release of X-rays	5.06	4.83

In a glove box to prepare the resulting spherical pelletsStage α -Ni (OH)₂The material is a positive electrode, PE is a diaphragm, a metal lithium sheet is a negative electrode, ethylene carbonate is electrolyte, and the material is pressed into a button cell with the diameter of 12mm to form a half cell. The prepared half cell is subjected to charge and discharge performance test in a blue battery test system, and the specific parameters are as follows: the current density is 1A/g, and the charge-discharge voltage range is 0V-3V. As can be seen from the line (2) in FIG. 4, the first discharge capacity reaches 1682.5mAh/g, the specific capacity after 630 cycles can be kept at 999mAh/g, and the capacity retention rate is about 59.4%.

Example 3

(1) Will analyze pure NiSO₄(3.875g) was dissolved in deionized water (50mL) and magnetically stirred at 100 rpm for 12 minutes to give solution A;

(2) adding Na into the solution A obtained in the step (1) under magnetic stirring₂S₂O₈(2.5g), stirring for 12 minutes to obtain a solution B;

(3) under magnetic stirring, adding 5ml of concentrated ammonia water (25-28%) into the solution B obtained in the step (2), and stirring for 12 minutes to obtain a solution C;

(4) and (4) adding 1g of commercial lithium ion battery negative copper foil into the solution C obtained in the step (3), wherein the thickness is 10 microns, the purity is more than or equal to 99.8 percent, and standing for 30 hours at room temperature.

(5) After the reaction is finished, the reaction product obtained in the step (4) is collected by centrifugation and washed for 10 times by water, and then the reaction product is dried for 18 hours in vacuum at 70 ℃ under the vacuum degree of 2000 Pa.

The reaction product is α -Ni (OH) also in hexagonal structure₂The XRD result corresponds to fig. 1- (4), the basic unit of the reaction product is a nano-sheet structure, and each nano-sheet layer is assembled into a multi-level spherical structure with a size of 0.5-3 μm, as shown in fig. 3(c) and 3(d), which are SEM images at 20000 times and 10000 times, respectively, it can be known from the figure that the morphology of the sample prepared by adding 2.5g of sodium persulfate, there are many gaps between each sheet layer, which is good for relieving the volume expansion, wherein the sheet α -ni (oh)₂The length and width ranges of the film are respectively 200-700 nm, and the thickness is 10-20 nm. The prepared sample to which 2.5g of sodium persulfate was added was subjected to energy spectrum analysis according to FIG. 8 and Table 3 belowThe data show that 2.5g of sodium persulfate produced a sample containing Ni, Cu, S, O in which the percentage by mass of copper incorporated was 21.11%.

TABLE 3

Kind of element	Atomic number	Characteristic X-ray	Mass percent of elements	Atomic percent of element
					Ni	28	K layer release of X-rays	39.10	17.96
O	8	K layer release of X-rays	37.21	67.67
					Cu	29	K layer release of X-rays	21.11	9.6
S	16	K layer release of X-rays	2.58	4.77

In a glove box to prepare a resulting spherical multilevel structure α -Ni (OH)₂The material is a positive electrode, PE is a diaphragm, a metal lithium sheet is a negative electrode, ethylene carbonate is electrolyte, and the material is pressed into a button cell with the diameter of 12mm to form a half cell. The prepared half cell is subjected to charge and discharge performance test in a blue battery test system, and the specific parameters are as follows: the current density is 1A/g, and the charge-discharge voltage range is 0V-3V. As can be seen from FIG. 4- (3), the first discharge capacity was 1520.5mAh/g, the specific capacity after 630 cycles was maintained at 900.4mAh/g (FIG. 4), and the capacity retention rate was about 59.2%.

The copper-doped nickel hydroxide prepared by the method has the potential of replacing a graphite cathode in a commercial lithium ion battery and realizing large-scale production.

Compared with the nickel hydroxide prepared in Chinese patent application 2015101803613, the cycle performance of the nickel hydroxide is obviously improved, and the first discharge capacity of the nickel hydroxide is 2237mAh g^-1At 100mA g^-1Current density of (1) and only 1107mAh g is left after 30 times of circulation^-1The capacity of the nickel hydroxide is maintained at about 50 percent, and the first discharge capacity of the copper-doped nickel hydroxide prepared by the method reaches 1715.6mAh/g and is 1A g^-1The specific capacity after 630 cycles can be kept at 1287.4mAh/g, and the capacity retention rate is about 75%.

The above-described embodiments are intended to be illustrative, rather than restrictive, and all such changes, modifications, substitutions, combinations, and simplifications that may be made without departing from the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims

1. The preparation method of the copper-doped spherical multilevel-structure nickel hydroxide material is characterized by comprising the following steps of:

(1) mixing NiSO₄Dissolving in deionized water, and stirring to obtain a solution A;

(2) adding Na into the solution A obtained in the step (1) under stirring₂S₂O₈Obtaining a solution B;

(5) and (4) after the reaction is finished, centrifugally collecting the reaction product obtained in the step (4), washing, and drying in vacuum to obtain the spherical multilevel-structure spherical nickel hydroxide material.

2. The method for preparing copper-doped spherical multilevel structure nickel hydroxide material according to claim 1, wherein the NiSO used in the step (1) is₄For analytical purposes, NiSO₄The concentration is 0.5 to 1 mol/L.

3. The method for preparing the copper-doped spherical multilevel-structure nickel hydroxide material according to claim 1, wherein the stirring in the steps (1), (2) and (3) is magnetic stirring, the rotating speed is 100-400 r/min, and the time is 12-18 min.

4. The method for preparing copper-doped spherical multilevel structure nickel hydroxide material according to claim 1, wherein in the step (2), Na is added₂S₂O₈With NiSO₄The mass ratio of (A) to (B) is 0.12:1 to 0.65: 1.

5. The method for preparing the copper-doped spherical multilevel-structure nickel hydroxide material according to claim 1, wherein the concentration of the ammonia water in the step (3) is 25-28%, and the volume of the ammonia water is 8-15% of the volume of the deionized water in the step (1).

6. Preparation of copper-doped spherical multilevel structure nickel hydroxide material according to claim 1The method is characterized in that the dosage of the copper foil in the step (4) is Na₂S₂O₈40-100% of the mass; and redundant copper foil is removed when being cleaned after the reaction is finished, the copper foil is a commercial lithium ion battery negative copper current collector, the thickness is 10 mu m, and the purity is more than or equal to 99.8%.

7. The method for preparing the copper-doped spherical multilevel structure nickel hydroxide material according to claim 1, wherein the washing in the step (5) is performed 5 times or more with water.

8. The method for preparing the copper-doped spherical multilevel-structure nickel hydroxide material according to claim 1, wherein the vacuum drying temperature in the step (5) is 60-80 ℃, the drying time is 12-24 h, and the vacuum degree of drying is 1000-4000 Pa.

9. A copper-doped spherical multilevel-structure nickel hydroxide material is characterized by being prepared by the preparation method of any one of claims 1 to 8; the basic unit of the spherical multilevel structure consists of nano-sheet Ni (OH)₂Composition of, in which the flake form Ni (OH)₂The length and width ranges of the film are respectively 200-700 nm, and the thickness is 5-20 nm.

10. The use of the copper-doped spherical multilevel structure nickel hydroxide material according to claim 9 in a secondary battery electrode material.