A method for preparing a multifunctional nanofiller with a single-ion conductor group and applications thereof

Abstract

The application belongs to the technical field of batteries, and specifically provides a preparation method of multifunctional nano filler with single-ion conductor groups and application thereof. The single-ion conductor is successfully grafted to a nanosheet layer material with rich hydroxyl groups. The modified material is used as a multifunctional nano filler to be compounded with a polymer solid electrolyte matrix. After modification, the dispersibility of the nanosheet in the polymer matrix is obviously optimized, and the mechanical properties and electrochemical properties of the composite solid electrolyte prepared by using the same are obviously improved. The multifunctional nano filler with single-ion conductor groups has a good application prospect in lithium metal batteries.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a method for preparing a multifunctional nanofiller with single-ion conductor groups and its application. Background Technology

[0002] To mitigate the challenges posed by global warming and the depletion of fossil fuels, my country has proposed a "dual-carbon" target. The key to achieving this target lies in promoting the transition from fossil fuels to clean energy. Wind and solar energy are the most abundant and readily available clean energy sources; however, they are not stable and reliable, are susceptible to weather conditions, and are typically located far from load centers. Energy storage systems, as energy carriers, will see tremendous development potential. Lithium-ion batteries, due to their high operating voltage, high energy density, long cycle life, and small footprint, have become the best choice for energy storage systems. However, most commercially available lithium-ion batteries currently use volatile and flammable organic electrolytes, posing a high risk of spontaneous combustion and explosion. In contrast, all-solid-state lithium metal batteries use solid electrolytes without liquid components, thus eliminating the risk of leakage and significantly improving battery safety.

[0003] Solid-state electrolytes can be classified into inorganic solid-state electrolytes and polymer solid-state electrolytes. Among them, polymer solid-state electrolytes are one of the most promising solid-state electrolytes due to their advantages such as high flexibility, low cost, and ease of integration. However, single polymer electrolytes often suffer from low room-temperature ionic conductivity due to high crystallinity, as well as narrow electrochemical windows and poor mechanical properties. Incorporating inorganic fillers into a polymer matrix to form composite solid polymer electrolytes (CSPEs) has become an effective method to solve these problems. The most common method for preparing CSPEs is to physically mix nanoscale fillers with polymer electrolytes. However, the interaction between physically added fillers and polymers is weak, and the fillers inevitably agglomerate, resulting in poor dispersion uniformity and limiting the improvement of electrolyte performance. Furthermore, traditional inorganic inert fillers can only improve ionic conductivity by reducing the crystallinity of the polymer matrix. Therefore, developing a novel functionalized nanofiller with single-ion conductor groups to achieve high-performance composite solid-state electrolytes while improving the dispersion of nanofillers in polymers will help promote the practical application of all-solid-state lithium metal batteries. Summary of the Invention

[0004] This invention aims to solve key problems of polymer solid electrolytes, namely low room temperature ionic conductivity, low lithium-ion transport number, and poor mechanical properties. Traditional nanofillers are difficult to disperse in polymer electrolytes and tend to agglomerate. Furthermore, inert fillers, lacking ionic conductivity, can only improve ionic conductivity by reducing the crystallinity of the polymer matrix and increasing chain segment movement, thus offering limited improvement to electrolyte performance. This invention provides a method for preparing multifunctional nanofillers with single-ion conductor groups and their applications. This method not only effectively improves the dispersibility of nanosheet materials in polymer electrolytes, but also significantly enhances the lithium-ion transport capacity of the polymer electrolyte due to the introduction of single-ion conductors. The polymer-based composite solid electrolyte prepared using this method exhibits excellent mechanical properties, and the assembled solid-state lithium metal battery also demonstrates excellent rate performance and cycle life. The technical solution adopted in this invention is as follows:

[0005] In a first aspect, a method for preparing a multifunctional nanofiller with a single-ion conductor group is provided, comprising the following steps:

[0006] Nanosheet fillers with abundant hydroxyl groups were prepared by hydrothermal synthesis. Then, they were organically modified with silane coupling agents to introduce polar groups -NH2 to prepare intermediates. Finally, single-ion conductors with sulfonic acid groups were grafted onto the intermediates of nanosheet materials through Michael addition reaction to obtain modified nanosheet fillers, namely multifunctional nanofillers with single-ion conductor groups.

[0007] Preferably, the nanosheet filler is one or more of the following layered compounds: nickel cobalt oxide, graphene oxide, hydroxylated boron nitride, zirconium hydrogen phosphate (ZrP), cobalt hydroxyoxide, montmorillonite, and hydrotalcite.

[0008] In this technical solution, "ZrP" refers to "zirconium hydrogen phosphate".

[0009] Preferably, the silane coupling agent is one or more of KH550, KH560, and KH580.

[0010] Furthermore, a specific method for preparing the aforementioned multifunctional nanofiller with single-ion conductor groups is provided:

[0011] Step 1: Prepare phosphorus source solution and zirconium source solution separately with distilled water, stir and mix evenly, and place the resulting mixed solution in a hydrothermal synthesis reactor. Heat at 180~220 ℃ for 10~24 h. After the hydrothermal reaction is completed, centrifuge and wash the solution in the reactor with deionized water until weakly neutral, dry and grind to obtain ZrP. Weigh ZrP and silane coupling agent and add them to an organic solvent, and ultrasonically disperse evenly. The obtained dispersion is refluxed under an inert gas atmosphere with stirring. Then centrifuge the dispersion obtained after the reaction to obtain silane coupling agent modified ZrP (ZrP-N). Centrifuge and wash several times with anhydrous ethanol to remove residual organic solvent, dry and grind to obtain ZrP-N powder.

[0012] Step 2: At 0 ℃ or below, a 30 wt% precursor solution of a single-ion conductor is added dropwise to a 30 wt% lithium hydroxide solution. The molar ratio of the single-ion conductor precursor to lithium hydroxide is 1:(1~5). After stirring for 10~24 h or more, the mixture is freeze-dried to obtain a single-ion conductor. ZrP-N is weighed and added to an N,N-dimethylacetamide (DMAC) solution, followed by the single-ion conductor. The mixture is refluxed and stirred under an inert gas atmosphere. The reaction product is washed several times with deionized water and anhydrous ethanol by centrifugation to remove impurities. The product is then placed in a forced-air drying oven. After drying, the product is ground to obtain a multifunctional nanofiller (ZrP-NS) with single-ion conductor groups.

[0013] Preferably, the zirconium source is ZrOCl2·8H2O, the phosphorus source is 85%wt phosphoric acid solution, the ZrP:silane coupling agent mass ratio is 1:1~10, the inert gas is argon, the condensation reflux stirring temperature is 60~120 ℃, and the condensation stirring reflux speed is 200~1000 r / min.

[0014] Preferably, in step two above, the precursor of the single-ion conductor is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid, bis(dodecanoic acid)sulfonic acid, p-trifluoromethanesulfonylstyrene, and diethylamine bis-(acylpropionic acid-α-sulfonic acid).

[0015] In a second aspect, a composite polymer solid electrolyte is provided, which includes the aforementioned multifunctional nanofiller with single-ion conductor groups.

[0016] Furthermore, the preparation method of the composite polymer solid electrolyte includes: weighing the multifunctional nanofiller with single-ion conductor groups and adding it to an organic solvent, ultrasonically stirring it thoroughly to disperse it evenly, then adding the polymer electrolyte matrix and conductive lithium salt in an argon-filled glove box, stirring and mixing thoroughly, and pouring the mixed solution into a mold to evaporate the organic solvent to obtain a polymer electrolyte membrane; the moisture content of the glove box is <0.01 ppm, and the oxygen content is <0.01 ppm;

[0017] Specifically: PEO and conductive lithium salt are added according to a molar ratio of "-EO" in PEO to "Li+" in conductive lithium salt of 10~20:1. The mixture is stirred for 12~20 h to ensure that PEO (molecular weight of 300,000~1,000,000) is fully dissolved in acetonitrile. The resulting solution is poured into a polytetrafluoroethylene mold and evaporated at room temperature under an argon atmosphere for 12~24 h to remove most of the acetonitrile solvent. The mold is then transferred to a vacuum drying oven at 45~60 ℃ and dried for 12~24 h to remove residual acetonitrile solvent. After drying, an untreated polymer electrolyte membrane is obtained. The membrane is peeled off from the polytetrafluoroethylene mold, wrapped with clean and dust-free release paper, and pressed in a flatbed hot press. After hot pressing, the membrane is cooled to obtain a thickness of 90~120 μm. The membrane is then cut into electrolyte membranes of the required size using a die-cutting machine.

[0018] Preferably, the polymer electrolyte matrix is ​​one or more of the following: polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyimide (PI), polymethyl methacrylate (PMMA), polycyanoacrylate (PCA), polyethylene carbonate (PEC), polypropylene carbonate (PPC), polytrimethylene carbonate (PTMC), and polyvinyl carbonate (PVC).

[0019] Preferably, the conductive lithium salt is one or more of LiPF6, LiBF4, LiClO4, LiFSI, LiTFSI, LiBOB, LiODFB, LiODFP, and LiPO2F2.

[0020] Thirdly, a lithium metal battery is provided, which uses a composite polymer solid electrolyte matched with a lithium metal anode as described above.

[0021] The beneficial effects of this invention are as follows: This invention prepares nanosheet materials through hydrothermal synthesis, then organically modifies them using a silane coupling agent, and finally introduces a single-ion conductor. The preparation process is simple and easy to mass-produce. When the functionalized nanosheet materials provided by this invention are applied to polymer solid electrolytes, a uniformly dispersed electrolyte membrane with good interfacial compatibility can be obtained. Furthermore, due to the introduction of the single-ion conductor and the polar group -NH2, the ionic conductivity and lithium-ion transference number of the electrolyte membrane can be effectively improved. When matched with a lithium metal anode, a polymer solid battery is prepared, which exhibits excellent rate performance and cycle life. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0023] Figure 1 XPS spectrum of the multifunctional nanosheet filler in Example 1;

[0024] Figure 2 Comparison of the mechanical properties of all-solid polymer electrolyte membranes prepared in Example 1, Comparative Example 1, and Comparative Example 2;

[0025] Figure 3 The graph shows a comparison of the rate performance of the all-solid-state polymer electrolytes prepared in Example 1, Comparative Examples 1 and 2 in Li / lithium iron phosphate batteries. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] (1) Preparation of positive electrode sheet

[0028] In the following embodiments, positive and negative electrode sheets for secondary lithium batteries are used, which are prepared by the following methods:

[0029] Lithium iron phosphate (LFP) active material, polyvinylidene fluoride (PVDF) binder, and conductive carbon were uniformly dispersed in an N-methylpyrrolidone (NMP) solution at a mass ratio of 8:1:1 and stirred at a constant speed for 16 h. The resulting slurry was cast onto aluminum foil using a doctor blade and vacuum dried at 80–100 °C for 12 h to obtain a thin film. The film was then stamped into a disc with a diameter of 12–14 mm to obtain the positive electrode. Commercially available lithium metal sheets were selected as the negative electrode for the secondary battery.

[0030] Example 1

[0031] A multifunctional nanofiller with single-ion conductor groups and a solid-state lithium metal battery using the same, the preparation method includes the following steps:

[0032] Step 1: Weigh a certain amount of ZrOCl2·8H2O at a molar ratio of 1:20 and add it to H3PO4 solution. After stirring and mixing evenly, place the resulting mixture in a hydrothermal synthesis reactor and heat at 180 ℃ for 24 h. After the hydrothermal reaction is complete, centrifuge and wash the solution in the reactor with deionized water until it is weakly neutral. After drying, grind to obtain ZrP. Weigh ZrP and silane coupling agent KH550 at a mass ratio of 1:4 and add them to 30 mL of toluene solution. Disperse evenly by ultrasonication. Reflux the resulting dispersion under an inert gas atmosphere with stirring until the reaction is complete. Centrifuge the resulting dispersion to obtain ZrP modified with silane coupling agent KH550 (ZrP-N), and wash several times with anhydrous ethanol to remove residual organic solvent. After drying, grind to obtain ZrP-N powder.

[0033] Step 2: At 0 ℃ or below, 30 wt% 2-acrylamide-2-methylpropanesulfonic acid (AMPS) solution was added dropwise to 30 wt% lithium hydroxide solution at a molar ratio of 1:1, and stirred for 12 h before freeze drying to obtain lithium 2-acrylamide-2-methylpropanesulfonic acid (AMPSLi); ZrP-N and AMPSLi were weighed at a molar ratio of 1:1 and added to 30 mL of N,N-dimethylacetamide (DMAC) solution, and refluxed and stirred under an inert gas atmosphere. The reaction product was washed several times with deionized water and anhydrous ethanol by centrifugation to remove impurities. The product was then placed in a forced-air drying oven, and ground after drying to obtain ZrP-NS;

[0034] Step 3: Add 1 wt% ZrP-NS to acetonitrile solvent and ultrasonically stir thoroughly to ensure uniform dispersion of the filler in acetonitrile. In an argon-filled glove box (moisture content <0.01 ppm, oxygen content <0.01 ppm), add PEO (Mw = 1000000) and LiTFSI according to a molar ratio of "-EO" in PEO to "Li+" in LiTFSI of 18:1, and stir for 24 h to ensure complete dissolution of PEO in acetonitrile. Pour the resulting solution into a polytetrafluoroethylene mold and evaporate at room temperature under an argon atmosphere for 24 h to remove most of the acetonitrile solvent. Then transfer the mold to a vacuum drying oven at 50 ℃ and dry for 24 h to remove residual acetonitrile solvent. After drying, the untreated polymer electrolyte membrane is obtained. Remove the film from the polytetrafluoroethylene mold, wrap it with clean, dust-free release paper, and place it in a flatbed hot press for pressing. After hot pressing and cooling, a film with a thickness of 90~120 μm is obtained. It was then cut into circular electrolyte membranes with a diameter of 16.5 mm using a punching machine, and used as the electrolyte for lithium metal batteries;

[0035] Step 4: Assemble the prepared electrolyte membrane, positive electrode, and commercial lithium sheet into a lithium metal coin cell, and perform relevant electrochemical performance tests on it.

[0036] XPS test results of functionalized nanosheet filler ZrP-NS in Example 1 are as follows: Figure 1 As shown, from Figure 1 The signal peaks of N and S elements can be clearly seen in the total spectrum, which come from KH550 and AMPSLi respectively. This test result shows that ZrP was successfully grafted onto the single-ion conductor AMPSLi, and ZrP-NS was successfully synthesized.

[0037] To verify whether the addition of functionalized nanosheet filler ZrP-NS can improve the mechanical properties of PEO polymer electrolytes, puncture tests were conducted on pure PEO, PEO-ZrP-N, and PEO-ZrP-NS electrolyte membranes. The test results are as follows: Figure 2 As shown, PEO-ZrP-NS exhibits the highest puncture stress resistance, with the electrolyte membrane only being punctured at a puncture force of 0.32 N, compared to pure PEO which was punctured by the puncture needle at only 0.18 N. Furthermore, PEO-ZrP-NS exhibits the largest strain, with the electrolyte membrane only being completely penetrated by the puncture needle after a displacement of 14 mm. This excellent puncture resistance effectively prevents lithium dendrites from puncturing the electrolyte membrane and causing battery failure.

[0038] Example 2

[0039] PEO with a molecular weight of 600,000 was used instead of PEO with a molecular weight of 1,000,000 as the polymer matrix, and the rest of the operation was the same as in Example 1.

[0040] Example 3

[0041] Replace KH550 with KH560, and perform the remaining operations as in Example 1.

[0042] Example 4

[0043] Replace KH550 with KH580, and perform the remaining operations as in Example 1.

[0044] Example 5

[0045] Replace EO:Li = 18:1 with 15:1, and perform the remaining operations as in Example 1.

[0046] Example 6

[0047] LiPF6 was used instead of LiTFSI, and the rest of the operation was the same as in Example 1.

[0048] Example 7

[0049] Change the ZrP and KH550 mass ratio from 1:4 to 1:10, and perform the remaining operations as in Example 1.

[0050] Example 8

[0051] Change the ZrP and KH550 mass ratio from 1:4 to 1:6, and perform the remaining operations as in Example 1.

[0052] Example 9

[0053] Change the ZrP and KH550 mass ratio from 1:4 to 1:2, and perform the remaining operations as in Example 1.

[0054] Example 10

[0055] Didodecanoic acid was used instead of 2-acrylamide-2-methylpropanesulfonic acid as the reaction monomer, and the rest of the operation was the same as in Example 1.

[0056] Example 11

[0057] p-Trifluoromethanesulfonylstyrene was used instead of 2-acrylamide-2-methylpropanesulfonic acid as the reaction monomer, and the rest of the operation was the same as in Example 1.

[0058] Example 12

[0059] Nickel cobalt oxide was used instead of ZrP as nanosheets, and the rest of the operation was the same as in Example 1.

[0060] Example 13

[0061] Graphene oxide was used instead of ZrP as nanosheets, and the rest of the operation was the same as in Example 1.

[0062] Example 14

[0063] Montmorillonite was used instead of ZrP as nanosheets, and the rest of the operation was the same as in Example 1.

[0064] Example 15

[0065] Cobalt hydroxyoxide was used instead of ZrP as nanosheets, and the rest of the operation was the same as in Example 1.

[0066] Example 16

[0067] Hydroxylated boron nitride was used instead of ZrP as nanosheets, and the rest of the operation was the same as in Example 1.

[0068] Comparative Example 1

[0069] Without adding ZrP-NS nanosheets to the PEO-based solid polymer electrolyte membrane, the rest of the operation is the same as in Example 1.

[0070] Comparative Example 2

[0071] ZrP-N was used instead of ZrP-NS nanosheets as filler to prepare PEO-based composite solid electrolyte membranes, and the remaining operations were the same as in Example 1.

[0072]

[0073] As can be seen from Table 1, the lithium iron phosphate solid-state full battery assembled with the all-solid-state polymer electrolyte prepared using the functionalized nanosheets synthesized in this invention has higher capacity and better capacity retention than the comparative example.

[0074] Figure 3 The graph shows the rate performance of the all-solid-state polymer electrolytes prepared in Example 1, Comparative Examples 1 and 2 in Li / lithium iron phosphate batteries. As can be seen from the graph, the Li / PEO-ZrP-NS / LFP all-solid-state battery exhibits the highest discharge specific capacity in the 0.1-2 C rate range. The discharge specific capacity reaches 151.82 mAh / g and 95.93 mAh / g under the 1 C and 2 C high rate conditions, respectively. This is attributed to the effective improvement of the lithium ion transference number of the PEO polymer electrolyte by the addition of functionalized nanofiller ZrP-NS, which significantly improves the electrochemical performance.

[0075] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a multifunctional nanofiller with a single-ion conductor group, characterized in that, Includes the following steps: Hydroxyl-containing nanosheet fillers were prepared by hydrothermal synthesis, and then organically modified with silane coupling agents to introduce polar groups -NH2 to prepare intermediates. Finally, single-ion conductors with sulfonic acid groups were grafted onto the nanosheet materials through Michael addition reaction to obtain modified nanosheet fillers, namely multifunctional nanofillers with single-ion conductor groups. The preparation method specifically includes: Step 1: Prepare phosphorus source solution and zirconium source solution separately with distilled water, stir and mix evenly, and place the resulting mixed solution in a hydrothermal synthesis reactor. Heat at 180~220 ℃ for 10~24 h. After the hydrothermal reaction is completed, centrifuge and wash the solution in the reactor with deionized water until weakly neutral, dry and grind to obtain ZrP. Weigh ZrP and silane coupling agent and add them to an organic solvent, and ultrasonically disperse evenly. The obtained dispersion is refluxed under an inert gas atmosphere with stirring. Then centrifuge the dispersion obtained after the reaction to obtain silane coupling agent modified ZrP. Centrifuge and wash several times with anhydrous ethanol to remove residual organic solvent, dry and grind to obtain ZrP-N powder. Step 2: At 0 ℃ or below, the precursor solution of the single-ion conductor is added dropwise to the lithium hydroxide solution. The molar ratio of the single-ion conductor precursor to lithium hydroxide is 1:(1~5). After stirring for 10~24 h or more, the mixture is freeze-dried to obtain the single-ion conductor. ZrP-N is weighed and added to N,N-dimethylacetamide solution, followed by the single-ion conductor. The mixture is refluxed and stirred under an inert gas atmosphere. The reaction product is washed several times with deionized water and anhydrous ethanol by centrifugation to remove impurities. The product is then placed in a forced-air drying oven. After drying, the product is ground to obtain the multifunctional nanofiller with single-ion conductor groups.

2. The method for preparing a multifunctional nanofiller with a single-ion conductor group according to claim 1, characterized in that: The nanosheet filler is one or more of nickel cobalt oxide, graphene oxide, hydroxylated boron nitride, zirconium hydrogen phosphate, cobalt hydroxyoxide, montmorillonite, and hydrotalcite.

3. The method for preparing a multifunctional nanofiller with a single-ion conductor group according to claim 1, characterized in that: The silane coupling agent is one or more of KH550, KH560, and KH580.

4. The method for preparing a multifunctional nanofiller with a single-ion conductor group according to claim 1, characterized in that: In step two, the precursor of the single-ion conductor is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid, bis(dodecanoic acid)sulfonic acid, p-trifluoromethanesulfonylstyrene, and diethylamine bis-(acylpropionic acid-α-sulfonic acid).

5. A composite polymer solid electrolyte comprising the multifunctional nanofiller with a single-ion conductor group as described in any one of claims 1-4.

6. The composite polymer solid electrolyte according to claim 5, characterized in that, The preparation method includes: weighing the multifunctional nanofiller with single-ion conductor groups and adding it to an organic solvent, stirring it thoroughly with ultrasonication to disperse it evenly, then adding a polymer electrolyte matrix and conductive lithium salt in an argon-filled glove box, stirring and mixing thoroughly, and pouring the mixed solution into a mold to evaporate the organic solvent to obtain a polymer electrolyte membrane; the moisture content of the glove box is <0.01ppm and the oxygen content is <0.01ppm.

7. The composite polymer solid electrolyte according to claim 5, characterized in that: The composite polymer solid electrolyte matrix is ​​one or more of the following: polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyimide, polymethyl methacrylate, polycyanoacrylate, polyethylene carbonate, polypropylene carbonate, polytrimethylene carbonate, and polyvinyl carbonate.

8. The composite polymer solid electrolyte according to claim 6, characterized in that: The conductive lithium salt is one or more of LiPF6, LiBF4, LiClO4, LiFSI, LiTFSI, LiBOB, LiODFB, LiODFP, and LiPO2F2.

9. A lithium metal battery, comprising a composite polymer solid electrolyte as described in claim 6 matched with a lithium metal anode.

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