PANI / PP modified diaphragm material and preparation and application thereof

Abstract

The invention relates to a preparation method of a PANI / PP modified diaphragm material, which comprises the following steps: mixing aniline and APS, and growing PANI on a commercial PP diaphragm in a perchloric acid solution through in-situ polymerization to form a vertical nano array structure modified layer. According to the invention, the adhesive force of the modified layer can be effectively improved, and the phenomena of low ion passing rate and non-uniform lithium ion flux caused by a stacked structure formed by a blade coating method are avoided. When the material is used for a lithium metal battery, the local current density can be reduced, and the generation of lithium dendrites is inhibited.

Description

Technical Field

[0001] The present invention belongs to the field of microelectronics technology, and in particular relates to a PANI / PP modified diaphragm material and a preparation method and application thereof. Background Art

[0002] With the rapid development of electric vehicles, consumer electronics and distributed energy, the energy density of conventional lithium-ion batteries and other general energy storage devices has been unable to meet the demand. The development of high energy density and high stability energy storage devices has become an important breakthrough in the transformation and upgrading of the lithium battery industry. Lithium metal batteries are a new type of battery system with a high theoretical capacity of up to 3860mAh g -1 , with a potential as low as -3.04V (referenced to standard hydrogen electrode), it has been widely studied in new generation battery systems such as lithium-sulfur and lithium-air, and is an ideal choice for realizing high energy density battery systems in the future.

[0003] However, the uncontrollable deposition of lithium ions increases the formation of "lithium dendrites", posing a serious safety hazard. Many strategies to inhibit the growth of "lithium dendrites" have made some progress, including increasing the three-dimensional lithium-philic structure carrier, adding high-concentration electrolytes, solid electrolytes and artificial electrolyte interfaces (SEI). Among them, the separator is an important medium in contact with the positive and negative electrodes in the battery component and is also the necessary channel for ion diffusion. Its composition and structure have a crucial impact on the overall performance of lithium metal batteries and play an important role in improving the diffusion efficiency of ions and achieving uniform deposition of lithium metal.

[0004] Through a lot of research, it is found that lithium nucleus has not entered the growth period, that is, Li + The process of migration from the electrolyte to the electrode is the key period for regulating lithium growth. Based on this theory, different methods of modifying the separator can achieve ideal deposition effects: an isolation coating containing high modulus inorganic substances (such as ceramic materials such as Al2O3 and SiO2) can improve the mechanical properties of the separator, enabling the separator to inhibit the growth of "lithium dendrites" and the volume expansion of active materials in the electrode, thereby improving industrial productivity; adding two-dimensional materials (such as graphene and conductive films) can improve Li + The transport performance of the membrane can effectively regulate the morphology of lithium deposition; the use of ordered pore structure and metal / covalent organic framework (MOFs / COFs) can improve ion mobility and cycle stability. At the same time, polar groups can promote the uniform deposition of lithium ions. Although the above methods have achieved remarkable results in optimizing the function of the membrane, there are still two key problems that need to be solved: (1) The pore size distribution of the membrane is uneven and the size is large, which causes the concentrated growth of lithium and leads to the formation of "lithium dendrites". Therefore, how to design the membrane modification layer to induce Li +Generate uniform flux; (2) The composite membrane obtained by the traditional coating method has slow ion transmission at the interface, and the addition of the binder makes it difficult for the modified material to fully play its role. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a preparation method and application of a PANI / PP modified diaphragm material, in which a polyaniline (PANI) ordered nanoarray with a vertical array structure is prepared on a PP diaphragm by a low-temperature in-situ polymerization method, and used as a diaphragm to assemble a lithium metal battery. The vertically arranged PANI nanowires provide a uniformly distributed ion channel for lithium ion diffusion. By regulating the Li + The flow direction promotes the uniform nucleation of lithium, thereby inhibiting the formation of "lithium dendrites" and improving the performance of lithium metal batteries.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A PANI / PP modified diaphragm material is composed of polyaniline vertically grown on a PP diaphragm, wherein the polyaniline is a nanowire structure and vertically grows on the PP diaphragm to form an ordered vertical nanoarray structure.

[0008] In one embodiment, the vertical growth size of polyaniline on the PP membrane is 200-400 nm, and the spacing is ∼100 nm.

[0009] The present invention also provides a method for preparing a PANI / PP modified diaphragm material, comprising the following steps:

[0010] Step 1, mixing perchloric acid and aniline monomer in an ice bath, stirring, and cooling to obtain a mixture;

[0011] Step 2: adding ammonium persulfate to perchloric acid and dispersing it evenly, then mixing it with the mixture, and placing the cut PP diaphragm into it, and aniline polymerization begins;

[0012] Step 3: After the polymerization is completed, the composite film of polyaniline and PP is taken out and repeatedly washed with deionized water and ethanol to finally obtain a PANI / PP composite membrane.

[0013] In one embodiment, in step 1, the concentration of perchloric acid is 0.1-2 mol / L, the amount used is 20-30 mL, the amount of aniline is 37.5 μL, and the temperature of the ice bath is 0° C.-5° C.

[0014] In one embodiment, in step 2, the amount of ammonium persulfate is 10-100 mg, the amount of perchloric acid used is such that the sum of the amount of perchloric acid used in step 1 is 40 mL, and the concentration of perchloric acid used in this step is preferably 1 mol / L.

[0015] In one embodiment, in step 2, the time for adding ammonium persulfate is 1-15 minutes. After the components are mixed, stirring is performed at a stirring rate of 100-500 rpm, and aniline polymerization begins.

[0016] In one embodiment, the PP membrane is a commercial Celgard membrane.

[0017] In one embodiment, in step 3, the polymerization reaction time is 5-36 hours.

[0018] The PANI / PP modified diaphragm material obtained by the present invention can be used to prepare diaphragms for lithium metal batteries.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] First, the present invention directly grows PANI ordered nanoarrays on the PP membrane by low-temperature polymerization, so that the polyaniline array effectively guides Li + flow direction, promoting the uniformity of lithium deposition,

[0021] Second, the PANI / PP composite diaphragm generated by direct polymerization overcomes the phenomenon that the functional layer of the composite diaphragm obtained by the traditional coating method is easy to peel off, and can better improve the cycle performance of lithium metal batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a scanning electron microscope image of the product prepared by the present invention.

[0023] Figure 2 This is a Raman test chart of the product prepared by the present invention. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0025] The present invention discloses a method for preparing a PANI / PP diaphragm composite material, the implementation scheme of which comprises the following steps:

[0026] Step 1: Mix perchloric acid (HClO4) and a certain amount of aniline monomer in an ice bath and stir for a period of time. After the perchloric acid and aniline mixed solution cools, place the cut PP diaphragm in the mixture.

[0027] In the present invention, perchloric acid and aniline are mixed in an ice bath, the perchloric acid is pre-cooled in advance, the two are mixed and stirred until cooled, and the PP diaphragm is cut into a circle and placed in the cooled mixed solution.

[0028] For example, the concentration of HClO4 is 0.1-2 mol / L, the total amount is 40 mL, the amount of aniline monomer added is 3-50 μL, the stirring time is 1-30 minutes, the diameter of the PP separator is 9-15 mm, and the size of the PP separator is 11-12 mm in diameter.

[0029] Step 2: Dissolve (NH4)2S2O8 (APS) in a perchloric acid aqueous solution, let it stand, and after it dissolves, slowly add it to the cooled mixed solution of HClO4 and aniline, slowly stir, and aniline polymerization begins.

[0030] In the present invention, APS is dissolved in a perchloric acid solution. The mixed solution is pre-cooled and allowed to stand to dissolve. APS is slowly added dropwise to the mixed solution of HClO4 and aniline using a rubber-tipped dropper while continuously stirring. At this point, the aniline polymerization reaction begins.

[0031] For example, the amount of APS added is 10-100 mg, and the static dissolution time is 1-30 min. To control the reaction rate, APS needs to be added slowly. In this embodiment, the addition time is 1-30 min. To control the nucleation growth rate of polyaniline on the PP membrane, the initial stirring rate is 100-500 rpm, and aniline slowly grows and polymerizes on the PP membrane.

[0032] Step 3: After the polymerization reaction is completed, the PANI-composite PP membrane is taken out and repeatedly washed with deionized water and ethanol to finally obtain a PANI / PP composite membrane.

[0033] In the present invention, the polymerization temperature and stirring rate remain unchanged, deionized water and ethanol are alternately and repeatedly washed, and the product is dried and stored.

[0034] For example, the polymerization temperature is 0-5°C, the stirring rate is 100-500 rpm, the number of repeated washings is 1-5 times, and the drying temperature is 30-60°C.

[0035] This composite PANI / PP separator with a vertical nanoarray structure, when used as a separator for lithium metal batteries, can effectively regulate the flow of lithium ions and reduce local current density compared to a two-dimensional stacked structure, thereby promoting the uniform deposition of lithium metal on the electrode surface, thereby inhibiting the growth of lithium dendrites. The present invention can effectively improve the adhesion of the modified layer, avoiding the phenomenon of low ion passage rate and uneven lithium ion flux caused by the stacked structure formed by the doctor blade method. Especially when applied to batteries, the modified layer is not easy to fall off the glass, thereby improving the problem of uneven lithium deposition caused by failure or peeling of the modified separator during the bending process of lithium metal batteries.

[0036] At the same time, the PANI / PP composite membrane directly polymerized on the PP membrane of the present invention overcomes the disadvantage that the functional layer obtained by the traditional coating method is easy to peel off, and the electrolyte is easier to infiltrate, overcoming the problem of difficulty in forming efficient electronic connections between coatings and slow interface charge transfer, thereby better improving the cycle performance of lithium metal batteries.

[0037] Reference Figure 1 , which is the vertical nano-array structure PANI / PP diaphragm composite material obtained by the present invention. It can be seen that PANI grows on the surface of the PP film in a vertical nano-array structure, and the overall structure is uniform and dense.

[0038] The present invention provides the following specific embodiments.

[0039] Example 1

[0040] Step 1: Mix 30 mL of 0.1 mol / L HClO₄ and 36.7 μL of aniline monomer in an ice bath and stir for 10 minutes. After the perchloric acid and aniline mixture cools, place a 12 mm diameter PP diaphragm in the mixture.

[0041] Step 2: Dissolve 61.5 mg of (NH4)2S2O8 (APS) in 10 mL of aqueous perchloric acid solution and let it stand for 10 min. After it dissolves, slowly add it (6 mg / min) to the cooled mixed solution of HClO4 and aniline with a stirring rate of 200 rpm. Aniline polymerization begins.

[0042] Step 3: After 24 hours of polymerization, the composite membrane of PANI and PP was taken out, washed twice with deionized water and ethanol, and dried at 40°C to finally obtain a PANI / PP composite membrane.

[0043] The product obtained in this example is reference Figure 1 and Figure 2 As shown, according to Figure 1 , we can clearly see that the neat PANI array is vertically distributed on the PP separator in an orderly manner. Figure 2 The Raman test results show that 1148 cm -1 , 1240cm -1 and 1313cm -1 The peaks at correspond to CN in the benzene ring and CN and CN in the quinone ring. + , at 1487cm -1 , 1567cm -1 and 1619cm -1 The peaks at correspond to C=N, C=C and C=C in the quinone ring.

[0044] Example 2

[0045] Step 1: Mix 30 mL of 0.1 mol / L HClO₄ and 25 μL of aniline monomer in an ice bath and stir for 20 minutes. After the perchloric acid and aniline mixture cools, place a 12 mm diameter PP diaphragm in the mixture.

[0046] Step 2: Dissolve 400 mg of (NH4)2S2O8 (APS) in 10 mL of aqueous perchloric acid solution and let it stand for 10 min. After it dissolves, slowly add it (4 mg / min) to the cooled mixed solution of HClO4 and aniline at a stirring rate of 200 rpm. Aniline polymerization begins.

[0047] Step 3: After the polymerization reaction for 12 hours, the composite membrane of PANI and PP was taken out, washed repeatedly with deionized water and ethanol three times, and dried at 40°C to finally obtain a PANI / PP composite membrane.

[0048] Example 3

[0049] Step 1: Mix 30 mL of 0.1 mol / L HClO₄ and 50 μL of aniline monomer in an ice bath and stir for 30 minutes. After the perchloric acid and aniline mixture cools, place a 12 mm diameter PP diaphragm in the mixture.

[0050] Step 2: Dissolve 20 mg of (NH4)2S2O8 (APS) in 10 mL of aqueous perchloric acid solution and let it stand for 20 min. After it dissolves, slowly add it (2 mg / min) to the cooled mixed solution of HClO4 and aniline at a stirring rate of 300 rpm. Aniline polymerization begins.

[0051] Step 3: After the polymerization reaction for 36 hours, the composite membrane of PANI and PP was taken out, washed repeatedly with deionized water and ethanol for 6 times, and dried at 60°C to finally obtain a PANI / PP composite membrane.

[0052] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown, but is intended to conform to the widest scope consistent with the principles and novel features of the present invention.

Claims

1. A PANI / PP modified diaphragm material, consisting of polyaniline vertically grown on a PP diaphragm.

2. The PANI / PP modified diaphragm material according to claim 1, characterized in that: The polyaniline is a nanometer array structure and grows vertically on the PP diaphragm to form an ordered vertical nanometer array structure.

3. The PANI / PP modified diaphragm material according to claim 1, characterized in that: The vertical dimension of the polyaniline grown on the PP membrane is 200-400 nm, and the spacing is 100 nm.

4. A method for preparing a PANI / PP modified diaphragm material, characterized in that: The steps include: Step 1, mixing perchloric acid and aniline monomer in an ice bath, stirring, and cooling to obtain a mixture; Step 2: Add ammonium persulfate to the perchloric acid solution and disperse it evenly, then mix it with the mixture in step 1, and place the cut PP diaphragm in the mixed solution to start aniline polymerization; Step 3: After the polymerization is completed, the PP composite film grown with polyaniline is taken out and repeatedly washed with deionized water and ethanol to finally obtain a PANI / PP composite membrane.

5. The method for preparing the PANI / PP modified diaphragm material according to claim 4, characterized in that: In the step 1, the concentration of perchloric acid is 0.1-2 mol / L, the amount used is 20-30 mL, the amount of aniline is 37.5 μL, and the temperature of the ice bath is 0° C.-5° C.

6. The method for preparing the PANI / PP modified diaphragm material according to claim 5, characterized in that: In the step 2, the amount of ammonium persulfate is 10-100 mg, and the amount of perchloric acid used is such that the sum of the amount of perchloric acid used in step 1 is 40 mL.

7. The method for preparing the PANI / PP modified diaphragm material according to claim 4, characterized in that: In the step 2, the rate of adding ammonium persulfate is 1-15 min. After the components are mixed, stirring is performed at a stirring rate of 100-500 rpm, and aniline polymerization begins.

8. The method for preparing the PANI / PP modified diaphragm material according to claim 4, characterized in that: The PP membrane is a commercial Celgard membrane.

9. The method for preparing the PANI / PP modified diaphragm according to claim 4, wherein: In the step 3, the polymerization reaction time is 5-36 hours.

10. Use of the PANI / PP modified diaphragm material according to claim 1 as a diaphragm for lithium metal batteries.

Images