A polymer electrolyte, and a method of preparing and use thereof

Abstract

The application provides a polymer electrolyte and a preparation method and use thereof. The polymer electrolyte comprises a polymer, an additive and a lithium salt; the additive comprises Sb6O 13 . The Sb6O 13 particle with a defective pyrochlore structure is added to the polymer electrolyte, which effectively improves the ion conductivity of the polymer electrolyte, and further improves the capacity and cycle performance of the solid-state battery.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, specifically to a polymer electrolyte, its preparation method, and its applications. Background Technology

[0002] With the ever-growing energy demands of the consumer electronics and electric vehicle markets, there is an urgent need to develop sustainable, high-energy-density, and highly safe energy storage devices. Among all energy storage devices, lithium-ion batteries have been extensively studied due to their excellent reversible capacity. However, traditional lithium-ion batteries utilize liquid electrolytes, which suffer from severe side reactions between the electrolyte and the electrodes, resulting in low capacity and poor cycle stability. Furthermore, liquid electrolytes pose risks such as leakage, leading to poor safety performance.

[0003] Solid polymer electrolytes possess advantages such as flexibility, ease of preparation, low cost, and good safety, and are considered the most promising candidate materials for achieving high specific energy density in high-voltage lithium batteries. Commonly used polymer substrates include PEO and PVDF, but their low ionic conductivity at room temperature hinders their practical application. Therefore, methods such as blending and doping are needed to modify them.

[0004] Therefore, how to improve the ionic conductivity of polymer-based solid electrolytes and thus enhance their electrochemical performance is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a polymer electrolyte, its preparation method, and its applications. The polymer electrolyte incorporates Sb6O with a defective pyrochlore structure. 13 The particles effectively improve the ionic conductivity of the polymer electrolyte, thereby enhancing the capacity and cycle performance of solid-state batteries.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a polymer electrolyte comprising a polymer, an additive, and a lithium salt; the additive comprising Sb6O 13 .

[0008] As a preferred embodiment of the present invention, the amount of the additive added is 5 to 10 wt% of the polymer.

[0009] As a preferred technical solution of the present invention, the Sb6O 13 These are secondary spherical particles assembled from primary particles.

[0010] As a preferred embodiment of the present invention, the D50 of the primary particles is 10-60 nm.

[0011] As a preferred embodiment of the present invention, the D50 of the secondary spherical particles is 20-300 μm.

[0012] As a preferred embodiment of the present invention, the polymer electrolyte further includes reduced graphene oxide, and the additive is dispersed on the sheet structure of the reduced graphene oxide.

[0013] As a preferred embodiment of the present invention, the amount of graphene oxide precursor added is 1 to 5% of the polymer substrate weight ratio.

[0014] As a preferred embodiment of the present invention, the polymer includes any one or a combination of at least two of polyvinylidene fluoride, polyethylene oxide, thermoplastic polyurethane, polypropylene oxide, polycarbonate, polyvinyl alcohol, polyacrylic acid, polyethyl methacrylate, polymethyl methacrylate, polyacrylonitrile, or polyvinyl chloride.

[0015] As a preferred embodiment of the present invention, the amount of lithium salt added is 25 to 40 wt% of the polymer.

[0016] As a preferred technical solution of the present invention, the lithium salt includes any one or a combination of at least two of the following: fluorinated lithium salt, lithium dioxaborate, lithium perchlorate, or lithium nitrate.

[0017] As a preferred technical solution of the present invention, the fluorinated lithium salt includes any one or a combination of at least two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalateborate, or lithium trifluoromethanesulfonate.

[0018] In a second aspect, the present invention provides a method for preparing a polymer electrolyte as described in the first aspect, the method comprising the following steps:

[0019] A polymer, lithium salt, additive, and solvent are mixed to obtain a mixed solution. The mixed solution is then formed into a film to obtain the polymer electrolyte. The additive includes Sb6O. 13 .

[0020] As a preferred embodiment of the present invention, the mixed solution further includes graphene oxide.

[0021] As a preferred embodiment of the present invention, when the mixed solution further includes graphene oxide, the mixing method includes:

[0022] First, the additives and graphene oxide are mixed once and reacted hydrothermally to obtain a composite structure. Then, the composite structure is mixed a second time with polymers, lithium salts and solvents to obtain a mixed solution.

[0023] As a preferred embodiment of the present invention, the temperature of the hydrothermal reaction is 180–220°C.

[0024] As a preferred embodiment of the present invention, the hydrothermal reaction time is 12 to 48 hours.

[0025] As a preferred embodiment of the present invention, the film-forming method includes solution coating film formation.

[0026] Thirdly, the present invention provides a solid-state battery, the solid-state battery comprising the polymer electrolyte as described in the first aspect.

[0027] Fourthly, the present invention also provides an Sb6O 13 Applications in polymer electrolytes.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The polymer electrolyte provided by this invention contains added Sb6O 13 With its defective pyrochlore structure, it can be added to polymer electrolyte systems as an inorganic additive to increase the amorphous regions in the polymer electrolyte. Furthermore, its unique valence state and structure act as a Lewis acid, combining with lithium salt anions to enable Li... + Better dissociation improves the ionic conductivity of the polymer electrolyte and effectively enhances its electrochemical performance. Detailed Implementation

[0030] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are merely illustrative of the present invention and should not be construed as limiting the invention.

[0031] Polymer solid electrolytes (SSEs) possess advantages such as flexibility, ease of preparation, low cost, and good safety, making them a promising candidate material for achieving high specific energy density in high-voltage lithium batteries. Commonly used polymer substrates include PEO and PVDF. For example, existing technologies disclose a composite polymer electrolyte and its preparation method, belonging to the field of lithium-ion battery electrolyte material design and preparation technology. This solid polymer electrolyte is composed of PVDF, PEO, nanoparticles, and lithium salts. However, its low ionic conductivity at room temperature hinders its practical application, thus requiring modification through blending and doping. Another example involves a 3D network structure all-solid-state electrolyte based on PEO polymer for all-solid-state lithium-ion batteries and its preparation method. This 3D network structure all-solid-state electrolyte uses modified graphene aerogel as the network framework, polyethylene oxide (PEO) as the polymer matrix, and poly(ethylene oxide) as the polymer matrix. A blend of ethylene glycol (PEG), fluoroethylene carbonate (FEC), and vinylene carbonate (VC) was used as a plasticizer. PEO, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and the plasticizer were blended together, and the blend was cast into a modified graphene aerogel to obtain an all-solid electrolyte. Another existing technology uses synthesized Sb2O5 nanoparticles with PEO and LiClO4 to prepare a composite polymer solid electrolyte (CPSE), and studies the relationship between the conductivity of CPSE and filler size, aging time, temperature, and heat treatment. However, it uses a hydrothermal method to synthesize Sb2O5, which is relatively complicated, and the ionic conductivity of the prepared solid electrolyte membrane is low.

[0032] Therefore, the ionic conductivity of polymer electrolytes in the prior art needs to be improved.

[0033] In one specific embodiment, the present invention provides a polymer electrolyte comprising a polymer, an additive, and a lithium salt; the additive comprising Sb6O 13 .

[0034] The polymer electrolyte provided by this invention contains added Sb6O 13 It has a defective pyrochlore structure (i.e., Sb6O). 13 The crystal lattice structure has defect sites. When added as an inorganic additive to a polymer electrolyte system, it can increase the amorphous regions in the polymer electrolyte. Furthermore, its special valence state and structure act as a Lewis acid, combining with lithium salt anions to enable Li... + Better dissociation improves the ionic conductivity of the polymer electrolyte and effectively enhances its electrochemical performance.

[0035] In a preferred embodiment, the amount of the additive is 5 to 10 wt% of the polymer, such as 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, or 10 wt%.

[0036] In this invention, adding too little additive does not significantly improve the ionic conductivity of the polymer solid electrolyte, while adding too much additive will not mix fully with the polymer substrate, resulting in precipitation and thus affecting the improvement of ionic conductivity.

[0037] As a preferred technical solution in a specific implementation, the Sb6O 13 These are secondary spherical particles assembled from primary particles.

[0038] Specifically, the D50 of the primary particles is 10–60 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, or 60 nm. The D50 of the secondary spherical particles is 20–300 μm, such as 20 μm, 50 μm, 75 μm, 100 μm, 125 μm, 150 μm, 175 μm, 200 μm, 225 μm, 250 μm, 275 μm, or 300 μm. In this application, the larger the particle size of the primary and secondary spherical particles, the worse their dispersibility in the polymer substrate, and the less significant the improvement in ionic conductivity.

[0039] In a preferred embodiment, the polymer electrolyte further includes reduced graphene oxide, and the additive is dispersed on the sheet structure of the reduced graphene oxide.

[0040] In this invention, the applicant innovatively adds reduced graphene oxide to the polymer electrolyte, and the reduced graphene oxide is compounded with additives, Sb6O 13 Uniformly dispersed on two-dimensional reduced graphene oxide sheets, it can be better dispersed in the polymer substrate in solution, and as a flexible material, it further reduces the crystallinity of solid polymer electrolytes, enhancing the migration ability of lithium ions in polymer segments; at the same time, the two-dimensional carbon network formed by the reduced graphene oxide material is beneficial to Li + The migration and diffusion of.

[0041] Furthermore, the amount of graphene oxide (GO), the precursor of the reduced graphene oxide, added is 1 to 5% of the polymer substrate weight ratio, for example, 1%, 2%, 3%, 4% or 5%.

[0042] In this invention, reduced graphene oxide (rGO) has high electronic conductivity. Excessive introduction (i.e., too much addition) will cause the polymer electrolyte to conduct electrons, resulting in a short circuit in the battery. If the addition is too little, the enhancement of lithium ion migration ability in the polymer chain segment is not obvious. Therefore, the range of the amount of reduced graphene oxide added is very important.

[0043] As a preferred embodiment, the polymer includes any one or a combination of at least two of polyvinylidene fluoride, polyethylene oxide, thermoplastic polyurethane, polypropylene oxide, polycarbonate, polyvinyl alcohol, polyacrylic acid, polyethyl methacrylate, polymethyl methacrylate, polyacrylonitrile, or polyvinyl chloride.

[0044] In a preferred embodiment, the amount of lithium salt added is 25 to 40 wt% of the polymer, such as 25 wt%, 27.5 wt%, 30 wt%, 32.5 wt%, 35 wt%, 37.5 wt%, or 40 wt%.

[0045] In this invention, if the amount of lithium salt added is too small, the measured ionic conductivity will be significantly lower than expected; if the amount of lithium salt added is too large, the polymer will be difficult to form a film.

[0046] As a preferred embodiment, the lithium salt includes any one or a combination of at least two of the following: fluorinated lithium salt, lithium dioxaborate, lithium perchlorate, or lithium nitrate.

[0047] More specifically, the fluorinated lithium salt includes any one or a combination of at least two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalateborate, or lithium trifluoromethanesulfonate.

[0048] In another specific embodiment, the present invention provides a method for preparing a polymer electrolyte as described in the above specific embodiments, the preparation method comprising the following steps:

[0049] A polymer, lithium salt, additive, and solvent are mixed to obtain a mixed solution. The mixed solution is then formed into a film to obtain the polymer electrolyte. The additive includes Sb6O. 13 .

[0050] The preparation method provided by this invention is simple to operate, has a short processing time, and is low in cost, and has extremely broad prospects for practical application.

[0051] In another preferred embodiment, the mixed solution further includes graphene oxide.

[0052] In another preferred embodiment, when the mixed solution further includes graphene oxide, the mixing method includes:

[0053] First, the additives and graphene oxide are mixed once and reacted hydrothermally to obtain a composite structure. Then, the composite structure is mixed a second time with polymers, lithium salts and solvents to obtain a mixed solution.

[0054] In this invention, the additive is first compounded with graphene oxide to achieve the goal of uniformly dispersing the additive on the graphene sheet structure.

[0055] As a preferred technical solution in another specific embodiment, the temperature of the hydrothermal reaction is 180-220°C, such as 180°C, 190°C, 200°C, 210°C, or 220°C.

[0056] As a preferred technical solution in another specific embodiment, the hydrothermal reaction time is 12 to 48 hours, such as 12 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, or 48 hours.

[0057] As a preferred technical solution in another specific embodiment, the film-forming method includes solution coating film formation.

[0058] In one application example, the present invention provides a solid-state battery, the solid-state battery comprising the polymer electrolyte described in the specific embodiments.

[0059] In another application example, the present invention also provides Sb6O 13 Applications in polymer electrolytes.

[0060] It should be noted that the Sb6O provided in this invention... 13 The preparation process of this substance is a conventional technical method, and the preparation method of this substance is applicable to all of them. The present invention adaptively provides a preparation process of this substance:

[0061] Sb₂O₅ solid particles, which are available on the market, are heated in air at a rate of 5°C / min, held at 500°C for 2 hours, and then cooled to obtain Sb₆O. 13 Particles.

[0062] Sb6O in the following embodiments 13 All particles were prepared using the methods described above.

[0063] Example 1

[0064] This embodiment provides a polymer electrolyte, which includes a polymer (polyvinylidene fluoride PVDF), a lithium salt (LiFSI), and an additive (Sb6O). 13 ).

[0065] The preparation method of the polymer electrolyte is as follows:

[0066] (1) Dissolve PVDF in N,N-dimethylformamide (DMF), and then add Sb6O at 7.5 wt% of the polymer mass. 13 Particles (D50 of primary particles is 30 nm, D50 of secondary particles is 50 μm) were mixed with a certain amount of LiFSI (equivalent to 30 wt% of the polymer mass) and magnetically stirred at 40 °C for 24 h to form a homogeneous mixture.

[0067] (2) Pour the mixture onto a clean glass plate, and dry it in a vacuum drying oven at 80°C for 8 hours using a solution coating method. Peel off the white film from the glass plate and cut the resulting film into Φ16mm circular electrolyte sheets to obtain the polymer electrolyte.

[0068] Example 2

[0069] The difference between this embodiment and Embodiment 1 is that the polymer in this embodiment is polyethylene oxide (PEO).

[0070] The remaining preparation methods and parameters are consistent with those in Example 1.

[0071] Example 3

[0072] The difference between this embodiment and Embodiment 1 is that the additive in this embodiment is dispersed on the sheet structure of graphene oxide.

[0073] In step (1) of the preparation method, 0.4g of Sb6O 13 Particles and 0.18 g of graphene oxide (GO) were dissolved in 30 ml of deionized water and magnetically stirred for 12 h. The mixture was then placed in a hydrothermal reactor and kept at 180 °C for 24 h to prepare Sb6O. 13 / rGO composite particles, then Sb6O 13 / rGO composite particles are mixed with polymer and lithium salt to obtain a homogeneous mixture.

[0074] The remaining preparation methods and parameters are consistent with those in Example 1.

[0075] Example 4

[0076] The difference between this embodiment and Embodiment 1 is that in step (1) of this embodiment, Sb6O 13 The amount of granules added is 5 wt% of the mass of the polymer PVDF.

[0077] The remaining preparation methods and parameters are consistent with those in Example 1.

[0078] Example 5

[0079] The difference between this embodiment and Embodiment 1 is that in step (1) of this embodiment, Sb6O 13 The amount of granules added is 10 wt% of the mass of the polymer PVDF.

[0080] The remaining preparation methods and parameters are consistent with those in Example 1.

[0081] Example 6

[0082] The difference between this embodiment and Embodiment 1 is that in step (1) of this embodiment, Sb6O 13 The amount of granules added is 3 wt% of the mass of the polymer PVDF.

[0083] The remaining preparation methods and parameters are consistent with those in Example 1.

[0084] Example 7

[0085] The difference between this embodiment and Embodiment 1 is that in step (1) of this embodiment, Sb6O 13 The amount of granules added is 15 wt% of the mass of the polymer PVDF.

[0086] The remaining preparation methods and parameters are consistent with those in Example 1.

[0087] Comparative Example 1

[0088] The difference between this comparative example and Example 1 is that the polymer electrolyte in this comparative example does not contain any additives.

[0089] The remaining preparation methods and parameters are consistent with those in Example 1.

[0090] Comparative Example 2

[0091] The difference between this comparative example and Example 1 is that the polymer electrolyte in this comparative example contains Sb2O5 as an additive.

[0092] The polymer electrolytes provided in Examples 1-7 and Comparative Examples 1-2 were used to construct SS / CSEs / SS simulated cells with two stainless steel electrodes (SS) for testing. The cell assembly process was carried out in a glove box where the water and oxygen content were both below 0.1 ppm. Electrochemical impedance spectroscopy (EIS) was performed at room temperature using a frequency range of 0.01 Hz to 106 Hz. The ionic conductivity of the prepared composite solid electrolyte was calculated from the impedance data obtained from the EIS test, and the final results are shown in Table 1.

[0093] Table 1

[0094] Ionic conductivity (S / cm) Example 1 <![CDATA[2.47×10 -5 ]]> Example 2 <![CDATA[2.99×10 -5 ]]> Example 3 <![CDATA[3.4×10 -5 ]]> Example 4 <![CDATA[1.84×10 -5 ]]> Example 5 <![CDATA[1.91×10 -5 ]]> Example 6 <![CDATA[0.97×10 -5 ]]> Example 7 <![CDATA[0.89×10 -5 ]]> Comparative Example 1 <![CDATA[0.54×10 -5 ]]> Comparative Example 2 <![CDATA[0.84×10 -5 ]]>

[0095] The polymer electrolytes (CSEs) provided in Examples 1-7 and Comparative Examples 1-2 were used to construct coin cells with lithium iron phosphate (LiFePO4) positive electrodes and lithium metal negative electrodes. All battery fabrication was performed inside a glove box. The batteries were subjected to charge-discharge cycle tests at a rate of 0.5C, and the results are shown in Table 2.

[0096] Table 2

[0097]

[0098]

[0099] Combining Table 1 and Table 2:

[0100] The data from Examples 1 and 3 show that introducing rGO into the polymer electrolyte can significantly improve the ionic conductivity of the composite solid electrolyte and enhance the charge-discharge cycle stability of the battery.

[0101] The data from Examples 1 and 4-7 show that when the amount of additive added is too small (less than 5 wt%), it has little effect on improving the ionic conductivity of the polymer electrolyte and little effect on the charge-discharge cycle stability of the battery; while when the amount added is too large (greater than 10 wt%), it will lead to excessive Sb6O... 13 The particles agglomerate, which reduces the ionic conductivity of the polymer electrolyte.

[0102] The data results from Example 1 and Comparative Example 1 show that if the polymer electrolyte does not contain the additives described in this application, its ionic conductivity is too low, which is not conducive to its cycle stability during charge and discharge.

[0103] The data from Example 1 and Comparative Example 2 show that using antimony-containing compounds of other valence states also cannot significantly improve the ionic conductivity of the composite solid electrolyte membrane and the battery charge-discharge cycle stability.

[0104] The polymer electrolyte (presented in the form of a polymer electrolyte membrane) provided by this invention contains added Sb6O 13 With its defective pyrochlore structure, it can be added to polymer electrolyte systems as an inorganic additive to increase the amorphous regions in the polymer electrolyte. Furthermore, its unique valence state and structure act as a Lewis acid, combining with lithium salt anions to enable Li... + Better dissociation improves the ionic conductivity of the polymer electrolyte and effectively enhances its electrochemical performance.

[0105] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polymer electrolyte, characterized by, The polymer electrolyte includes a polymer, an additive, and a lithium salt; the additive includes Sb6O 13 .

2. The polymer electrolyte according to claim 1, wherein The amount of the additive added is 5 to 10 wt% of the polymer.

3. The polymer electrolyte according to claim 1, wherein Sb6O 13 Secondary spherical particles assembled from primary particles.

4. The polymer electrolyte according to claim 3, wherein The D50 of the primary particles is 10~60nm.

5. The polymer electrolyte according to claim 3, wherein The D50 of the secondary spherical particles is 20~300μm.

6. The polymer electrolyte according to claim 1, wherein The polymer electrolyte also includes reduced graphene oxide, and the additive is dispersed on the sheet structure of the reduced graphene oxide.

7. The polymer electrolyte according to claim 6, wherein The amount of graphene oxide, the precursor of the reduced graphene oxide, added is 1 to 5% of the polymer weight.

8. The polymer electrolyte according to claim 1, wherein The polymer includes any one or a combination of at least two of the following: polyvinylidene fluoride, polyethylene oxide, thermoplastic polyurethane, polypropylene oxide, polycarbonate, polyvinyl alcohol, polyacrylic acid, polyethyl methacrylate, polymethyl methacrylate, polyacrylonitrile, or polyvinyl chloride.

9. The polymer electrolyte according to claim 1, wherein The amount of lithium salt added is 25 to 40 wt% of the polymer.

10. The polymer electrolyte according to claim 1, wherein The lithium salt includes any one or a combination of at least two of the following: fluorinated lithium salt, lithium dioxaborate, lithium perchlorate, or lithium nitrate.

11. The polymer electrolyte according to claim 10, wherein The fluorinated lithium salt includes any one or a combination of at least two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalateborate, or lithium trifluoromethanesulfonate.

12. A method for producing the polymer electrolyte according to any one of claims 1 to 11, characterized by, The preparation method includes the following steps: The polymer, lithium salt, additive and solvent are mixed to obtain a mixed solution, and the mixed solution is formed into a film to obtain the polymer electrolyte; the additive includes Sb6O 13 .

13. The method for preparing the polymer electrolyte according to claim 12, characterized in that, The mixed solution also includes graphene oxide.

14. The method of claim 13, wherein the polymer electrolyte is prepared by mixing the polymer, the electrolyte, and the additive. When the mixed solution also includes graphene oxide, the mixing method includes: First, the additives and graphene oxide are mixed once and reacted hydrothermally to obtain a composite structure. Then, the composite structure is mixed a second time with polymers, lithium salts and solvents to obtain a mixed solution.

15. The method of claim 14, wherein the polymer electrolyte is prepared by mixing the polymer, the electrolyte, and the additive. The temperature of the hydrothermal reaction is 180~220℃.

16. The method for preparing the polymer electrolyte according to claim 14, characterized in that, The hydrothermal reaction time is 12-48 hours.

17. The method for preparing the polymer electrolyte according to claim 12, characterized in that, The film-forming method includes solution coating film formation.

18. A battery, characterized in that, The battery comprises a polymer electrolyte as described in any one of claims 1-11.

19. A Sb6O12 pyrochlore structure having defects 13 Use in polymer electrolytes.

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