NiO@PPy composite material, and preparation method and application thereof

Abstract

The application discloses a kind of NiO@PPy composite material and preparation method thereof, preparation method includes the following steps: preparation NiO microsphere, nickel source and hexamethylenetetramine are reacted by hydrothermal reaction, and NiO microsphere is prepared by calcination;Preparation NiO@PPy composite material, NiO microsphere, oxidizing agent, pyrrole monomer, halide dopant and surfactant are reacted in solution to obtain the NiO@PPy composite material.The application also discloses the use of the above-mentioned NiO@PPy composite material in the preparation of batteries.The NiO@PPy composite material provided by the application has good mechanical stability and electrochemical performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a NiO@PPy composite material and a preparation method and application thereof. BACKGROUND

[0002] Lithium ion batteries have the advantages of high capacity, good cycle performance, small irreversible capacity, good rate performance, and stable electrochemical performance in electrolyte, and are a hot research direction. At present, the most reported negative electrode materials of lithium ion batteries are carbon-based materials, including amorphous carbon materials and graphite carbon materials, but the space for capacity increase of such materials is small. In addition, there are silicon-based, tin-based and transition metal oxide lithium ion battery negative electrode materials. However, the silicon-based and tin-based materials will have a serious expansion and contraction phenomenon during charging and discharging, causing the structure of the active material to be unstable or collapse, thereby affecting the cycle performance and coulomb efficiency.

[0003] Transition metal oxides are one of the most promising negative electrode materials for lithium ion batteries due to their high theoretical specific capacity, low electrode potential, low price and environmental friendliness. The negative electrode composed of transition metal oxide nanostructures has a significantly higher theoretical capacity (>600 mAh g -1 ) than the most advanced graphite material (372 mAh g -1 ). Among them, nickel oxide (NiO) is easy to obtain and simple to prepare, has a high theoretical specific capacity (about 718 mAh g -1 ), and is expected to become the next generation of negative electrode material for lithium ion batteries.

[0004] The morphology and size of transition metal oxides are one of the key factors affecting the lithium storage performance of the material. Therefore, they are usually prepared into nanoscale materials or porous materials. The hybrid structure composed of carbon and transition metal oxides has high stability and can well balance the capacity and rate capability, in which the transition metal oxides provide high capacity, and the carbon matrix provides good electrical conductivity and stability. Reasonable control of the composite morphology between the two plays an active role in reducing material volume expansion and preventing self-aggregation. SUMMARY

[0005] In view of the above background, the present application provides a NiO@PPy (poly-pyrrole) composite material and a preparation method and application thereof. The NiO@PPy composite material prepared by the present application has a porous nanostructure and has excellent electrochemical performance as a negative electrode material for lithium ion batteries.

[0006] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0007] In one aspect, the present application provides a preparation method of NiO@PPy composite material, comprising the following steps:

[0008] (1) Preparation of NiO microspheres

[0009] The nickel source and hexamethylene tetramine are subjected to hydrothermal reaction, and NiO microspheres are prepared by calcination;

[0010] (2) Preparation of NiO@PPy composite material

[0011] The NiO microspheres, oxidizing agent, pyrrole monomer, halide dopant and surfactant are reacted in a solution to obtain the NiO@PPy composite material.

[0012] As a preferred embodiment, in step (1), the nickel source is a nickel salt selected from at least one of nickel nitrate, nickel chloride, nickel acetate and nickel sulfate;

[0013] Preferably, the molar ratio of nickel in the nickel source to hexamethylene tetramine is 1-1.6:2.

[0014] As a preferred embodiment, in step (1), the temperature of the hydrothermal reaction is 100-120°C;

[0015] Preferably, the time of the hydrothermal reaction is 4-6h, and further preferably 5h.

[0016] As a preferred embodiment, in step (1), the temperature of the calcination is 300-400°C;

[0017] Preferably, the time of the calcination is 1.5-2h;

[0018] Preferably, the heating rate of the calcination is 1-3°C / min;

[0019] Preferably, the calcination is carried out in an air atmosphere.

[0020] In some specific embodiments, in step (1), after the hydrothermal reaction, it further comprises washing and drying treatment; the washing is water and ethanol washing; and the drying is drying at 60-80°C for 10-12h.

[0021] As a preferred embodiment, in step (2), the oxidizing agent is selected from at least one of ammonium persulfate, hydrogen peroxide, iron oxide and ferric chloride;

[0022] Preferably, the amount of the NiO microspheres and the oxidizing agent is in a relationship that 60mg of NiO microspheres corresponds to 0.2-0.3g of oxidizing agent;

[0023] Preferably, the halide dopant is selected from at least one of HCl, HBr and HF;

[0024] Preferably, the amount of the halide dopant is 0.01-0.02 mol halide per 1 g of the NiO microspheres in terms of the amount of substance of the halide;

[0025] Preferably, the amount of the NiO microspheres and the pyrrole monomer is 0.060-0.075 mL of the pyrrole monomer per 60 mg of the NiO microspheres.

[0026] Preferably, the surfactant is at least one selected from the group consisting of sodium dodecyl sulfate, ammonium dodecyl sulfate and cetyltrimethylammonium bromide.

[0027] Preferably, the amount of the NiO microspheres and the surfactant is 2-10 mg of the surfactant per 60 mg of the NiO microspheres.

[0028] As a preferred embodiment, in step (2), the temperature of the reaction is 0-5°C; and the reaction time is 3-4 h.

[0029] In some specific embodiments, in step (2), the reaction is further followed by washing and drying; the washing is water and ethanol washing; and the drying is drying at 60-80°C for 10-12 h.

[0030] In some specific embodiments, step (2) specifically comprises:

[0031] S1. preparing a dispersion containing NiO microspheres and a surfactant;

[0032] S2. mixing the dispersion of step S1 with a halide dopant and a pyrrole monomer, and stirring at 0-5°C.

[0033] S3. mixing the mixture of step S2 with ammonium persulfate, and stirring at 0-5°C.

[0034] In some specific embodiments, in step S1, the preparation of the dispersion containing NiO microspheres and a surfactant is adding the NiO microspheres into a dispersion containing a surfactant, ultrasonic treatment for 20-30 min, and stirring at 600-800 rpm for 3-4 h; and the dispersion containing the surfactant is obtained by dispersing the surfactant in water, and stirring at 500-700 rpm for 20-30 min.

[0035] In some specific embodiments, in step S2, the mixing is adding the halide dopant and the pyrrole monomer into the dispersion of step S1; and the stirring is stirring at 600-800 rpm for 1-2 h.

[0036] In some specific embodiments, in step S3, the mixing is adding ammonium persulfate or a solution thereof into the mixture obtained in step S2; and the stirring is stirring at 500-600 rpm for 3-4 h.

[0037] In another aspect, the present application provides the NiO@PPy composite material prepared by the above method.

[0038] In another aspect, the present application provides the use of the above NiO@PPy composite material in preparing a battery.

[0039] Preferably, the use is in preparing a lithium ion battery.

[0040] Preferably, the use is in preparing a negative electrode material of a lithium ion battery.

[0041] The above technical solution has the following advantages or beneficial effects:

[0042] The present application provides a core-shell structured NiO@PPy composite material, which is prepared by a hydrothermal method and a chemical in-situ polymerization method. In the polymerization process, polypyrrole is coated on the surface of nanoflower NiO microspheres formed by self-assembly of a lamellar structure, which endows the composite material with good mechanical stability and electrochemical performance. In addition, in the present application, the NiO@PPy composite material not only improves the electrical conductivity of polypyrrole, but also has a weak alkalinity and a small influence on the distribution of positive charges of the polypyrrole main chain, which is conducive to the transmission of charges, thereby having good electrochemical performance.

[0043] Compared with the prior art, the present application has the following advantages:

[0044] (1) The core-shell structure of the NiO@PPy composite material prepared by the present application can avoid particle breakage and aggregation, thereby ensuring the structural stability in the charge and discharge cycle; in addition, the coated polypyrrole improves the electrical conductivity of the NiO microspheres, which exhibits high reversible capacity, good cycle performance and excellent rate performance;

[0045] (2) The preparation method provided by the present application first prepares a precursor Ni(OH)2 by a hydrothermal method, and then obtains NiO microspheres by calcination. This process can control the morphology of the NiO microspheres by controlling the reaction conditions, such as the proportion of raw materials, the calcination temperature, etc., so as to obtain NiO microspheres with uniform size and morphology;

[0046] (3) The NiO@PPy composite material provided by the present application is a nanocomposite material with a large specific surface area, thereby exhibiting higher electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a TEM image of the NiO@PPy nanocomposite material prepared in Example 1 of the present application.

[0048] Figure 2 is the cycle stability curve of the NiO@PPy nanocomposite prepared in Example 1 of the present application.

[0049] Figure 3 is the rate performance graph of the NiO@PPy nanocomposite prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0050] The following examples are merely exemplary of some of the embodiments of the present application and therefore are not intended to limit the scope of the application, which is defined by the appended claims. Based on the examples of the present application, those skilled in the art will be able to attain all the other embodiments without making an inventive effort.

[0051] In the present application, all the equipment and raw materials, unless specified, can be purchased from the market or commonly used in the industry. The methods in the following examples, unless specified, are the conventional methods in the art.

[0052] Example 1

[0053] This example provides a NiO@PPy nanocomposite, which is prepared as follows:

[0054] (1) Preparation of NiO microspheres

[0055] Dissolve 2.91 g of Ni(NO3)2·6H2O and 2.80 g of hexamethylenetetramine in 60 mL of ultrapure water in sequence, and stir for 30 min; load the stirred solution into an 80 mL Teflon-lined stainless steel autoclave, and react in a 120℃ oven for 5 h; wash the synthesized product with deionized water and anhydrous ethanol for 3 times in sequence, and then place it in a vacuum drying oven at 80℃ for 12 h; then grind the dried sample into a uniform powder with a mortar, and then place it in a tube furnace for calcination in an air atmosphere, with a calcination process of 300℃ for 2 h and a heating rate of 1℃ / min, to obtain a NiO microsphere sample.

[0056] (2) Preparation of NiO@PPy nanocomposite

[0057] Weigh 5 mg of sodium dodecyl sulfate and disperse it in 50 mL of deionized water, and stir at 600 rpm for 30 min; weigh 60 mg of the NiO microsphere sample and add it to the above solution, and ultrasonically treat for 30 min, and then stir at 600 rpm and room temperature for 3 h, denoted as solution A;

[0058] Take 1 mL of 1 mol / L HCl solution and 0.060 mL of pyrrole monomer and add them to solution A successively, stir at 600 rpm under ice water bath for 1 h, and mark it as solution B;

[0059] Weigh 0.2 g of ammonium persulfate and dissolve it in 10 mL of H2O, stir to obtain a uniform solution C; add solution C dropwise to solution B, stir at 500 rpm in an ice water bath for 3 h; wash the product with deionized water and anhydrous ethanol for 3 times respectively, and place the washed black solid sample in a vacuum drying oven at 80℃ for 12 h to obtain the NiO@ppy nanocomposite.

[0060] Performance test

[0061] 1. Figure 1 The TEM image of the NiO@ppy nanocomposite synthesized in this example shows that the nanocomposite has a flower-like structure formed by self-assembly of sheet layers, and the PPy layers are uniformly and closely coated on the surface of NiO to form a core-shell structure.

[0062] 2. Put the NiO@ppy nanocomposite or the NiO microspheres prepared in step (1) into a mortar in a mass ratio of 8:1:1 with Ketjen black and polyvinylidene fluoride (PVDF), mix uniformly, add appropriate amount of N-methyl pyrrolidone (NMP) to make slurry and continue to mix; uniformly coat it on a copper foil, dry it in a vacuum oven at 120℃, and obtain the copper foil with active material after drying, cut it into electrode pieces, and select the round electrode pieces with a loading amount of 1 mg / cm 2 for use. Prepare CR-2032 type button cells with the above round electrode pieces as negative electrodes, and the preparation process is carried out in a glove box filled with inert argon, the water and oxygen value in the glove box is controlled within 0.01 ppm, and the electrolyte is commercial lithium battery electrolyte, with 1.0 mol / L LiPF6 as solute, and ethylene carbonate: dimethyl carbonate: diethyl carbonate in a volume ratio of 1:1:1 as electrolyte solvent.

[0063] Perform 1 Ag -1 cycle life test on the above battery on a blue light tester, and the test results are shown in Figure 2 From the figure, it can be seen that although the NiO microspheres have higher specific capacity, they continuously decay during the cycle, and decay to 150 mAh g -1 after 500 cycles, and the cycle stability is only 14.2%, while the capacity of NiO@PPy can be stably maintained at about 400 mAh g -1 after 500 cycles, and the cycle stability is 70.1%.

[0064] The above batteries were subjected to rate performance tests using a blue battery tester, with a test voltage range of 0.01–3V. The test results are shown below. Figure 3 .from Figure 3 As can be seen from the data, NiO microspheres at concentrations of 0.1, 0.2, 0.4, 0.5, 1, 2, and 4 Å g... -1 At that time, the values ​​were 1056, 986, 905, 864, 718, 394, and 107 mAh g, respectively. -1 The average discharge specific capacity when the current density recovers to 0.1Ag -1 At that time, the capacity was restored to 865mAh g -1 NiO@PPy nanomaterials in 0.1, 0.2, 0.4, 0.5, 1, 2, and 4 Ag... -1 At that time, the values ​​were 812, 634, 500, 468, 382, ​​273, and 138 mAh g, respectively. -1 The average discharge specific capacity when the current density recovers to 0.1Ag -1 At that time, the capacity was restored to 726mAh g. -1 It can be seen that although NiO has a higher specific capacity at low currents, it is less effective at 1, 2, and 4 A g. -1 The capacity of NiO@PPy exhibits significant degradation under high current, while NiO@PPy shows better stability under high current.

[0065] Example 2

[0066] This embodiment provides a NiO@PPy nanocomposite material, and the preparation process is as follows:

[0067] (1) Preparation of NiO microspheres

[0068] 3.50 g Ni(NO3)2·6H2O and 2.80 g hexamethylenetetramine were dissolved sequentially in 60 mL of ultrapure water and stirred for 25 min. The stirred solution was then placed in an 80 mL stainless steel autoclave lined with Teflon and reacted in an oven at 110 °C for 5 h. The synthesized product was washed four times with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 70 °C for 10 h. The dried sample was then ground into a uniform powder using a mortar and pestle, and then calcined in a tube furnace in an air atmosphere at 250 °C for 1.5 h with a heating rate of 2 °C / min to obtain NiO microsphere samples.

[0069] (2) Preparation of NiO@ppy nanocomposites

[0070] Take 5 mg of sodium dodecyl sulfate and disperse it in 50 mL of deionized water, stir at 700 rpm for 20 min; take 60 mg of NiO microsphere sample and add it to the above solution, ultrasonic treatment for 20 min, then stir at 700 rpm and room temperature for 3 h, mark it as solution A;

[0071] Take 1 mL of 1 mol / L HCl solution and 0.065 mL of pyrrole monomer and add them to solution A successively, stir at 600 rpm under ice water bath for 1 h, mark it as solution B;

[0072] Take 0.2 g of ammonium persulfate and dissolve it in 10 mL of H2O, stir to obtain a uniform solution C; add solution C dropwise to solution B, stir at 500 rpm in an ice water bath for 3 h; wash the product with deionized water and anhydrous ethanol 4 times respectively, put the washed black solid sample into a vacuum drying oven at 80℃ for 12 h, obtain NiO@ppy nanocomposite.

[0073] Example 3

[0074] This example provides a NiO@PPy nanocomposite, the preparation process is as follows:

[0075] (1) Preparation of NiO microspheres

[0076] Dissolve 4.37 g of Ni(NO3)2·6H2O and 2.80 g of hexamethylenetetramine in 60 mL of ultrapure water successively, stir for 30 min; put the stirred solution into a 80 mL stainless steel autoclave lined with Teflon, react in a 100℃ oven for 5 h; wash the synthesized product with deionized water and anhydrous ethanol 3 times respectively, then put it into a vacuum drying oven at 65℃ for 12 h; grind the dried sample into a uniform powder with a mortar, then put it into a tube furnace for calcination in an air atmosphere, the calcination process is 2 h at 200℃ with a heating rate of 2℃ / min, obtain NiO microsphere sample.

[0077] (2) Preparation of NiO@ppy nanocomposite

[0078] Take 5 mg of sodium dodecyl sulfate and disperse it in 50 mL of deionized water, stir at 500 rpm for 30 min; take 60 mg of NiO microsphere sample and add it to the above solution, ultrasonic treatment for 30 min, then stir at 500 rpm and room temperature for 3 h, mark it as solution A;

[0079] Take 1 mL of 1 mol / L HCl solution and 0.070 mL of pyrrole monomer and add them to solution A successively, stir at 600 rpm under ice water bath for 1 h, mark it as solution B;

[0080] Take 0.2 g of ammonium persulfate and dissolve it in 10 mL of H2O, stir to obtain a uniform solution C; add solution C dropwise to solution B, stir at 500 rpm in an ice water bath for 3 h; wash the product with deionized water and anhydrous ethanol 4 times respectively, and place the washed black solid sample in a vacuum drying oven at 80°C for 12 h to obtain a NiO@ppy nanocomposite.

[0081] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for preparing a NiO@PPy composite material, characterized in that, The method comprises the following steps: (1) preparing NiO microspheres A nickel source and hexamethylenetetramine are subjected to a hydrothermal reaction to prepare the NiO microspheres by calcination; (2) preparing NiO@PPy composite material The NiO microspheres, an oxidizing agent, a pyrrole monomer, a halide dopant and a surfactant are reacted in a solution to obtain the NiO@PPy composite material; in the NiO@PPy composite material, polypyrrole is coated on the surface of nanoflower NiO microspheres formed by self-assembly of a lamellar structure; In step (1), the nickel source is a nickel salt selected from at least one of nickel nitrate, nickel chloride, nickel acetate and nickel sulfate; the molar ratio of nickel in the nickel source to hexamethylenetetramine is 1-1.6:2; the temperature of the hydrothermal reaction is 100-120℃; the time of the hydrothermal reaction is 4-6 h; the temperature of the calcination is 300-400℃; and the time of the calcination is 1.5-2 h; In step (2), the temperature of the reaction is 0-5℃; the time of the reaction is 3-4 h; the amount of the NiO microspheres and the pyrrole monomer is in a relationship that 0.060-0.075 mL of the pyrrole monomer corresponds to 60 mg of the NiO microspheres; the oxidizing agent is ammonium persulfate; the amount of the NiO microspheres and the oxidizing agent is in a relationship that 0.2-0.3 g of the oxidizing agent corresponds to 60 mg of the NiO microspheres; the halide dopant is HCl; the amount of the halide dopant is 0.01-0.02 mol of halide / 1 g of NiO microspheres; and the surfactant is sodium dodecyl sulfate; the amount of the NiO microspheres and the surfactant is in a relationship that 2-10 mg of the surfactant corresponds to 60 mg of the NiO microspheres; Step (2) specifically comprises: S1. preparing a dispersion liquid containing the NiO microspheres and the surfactant; S2. mixing the dispersion liquid of step S1 with the halide dopant and the pyrrole monomer, and stirring at 0-5℃; and S3. mixing the mixture of step S2 with ammonium persulfate, and stirring at 0-5℃.

2. The production method according to claim 1, characterized by, In step (1), the time of the hydrothermal reaction is 5 h.

3. The preparation method according to claim 1, characterized in that, In step (1), the heating rate of the calcination is 1-3℃ / min.

4. The method of claim 1, wherein, In step (1), the calcination is performed in an air atmosphere.

5. The NiO@PPy composite material prepared by the method of any one of claims 1-4.

6. Use of the NiO@PPy composite material of claim 5 in preparing a lithium ion battery negative electrode material.

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