Polyamide semi-solid electrolyte and preparation method and application thereof

Abstract

The invention discloses a polyamide semi-solid electrolyte, which comprises polyamide, a lithium salt and an electrolyte, wherein the polyamide is obtained by polymerizing polybasic acyl halide, 4, 4 '-diamino-2, 2'-bis (trifluoromethoxy) benzidine and a diamine monomer 1; the diamine monomer 1 is at least one of amino-terminated polyethylene glycol and amino-terminated polysiloxane. The invention also discloses a preparation method of the polyamide semi-solid electrolyte, which comprises the following steps: carrying out polymerization reaction on 4 '-diamino-2, 2'-bis (trifluoromethoxy) benzidine, a diamine monomer 1 and polybasic acyl halide in an organic solvent, and adding proline to remove HCl so as to obtain a polyamide solution; then adding lithium salt into the polyamide solution, and uniformly mixing to prepare a thin film; and soaking or wetting the thin film with an electrolyte to obtain the polyamide semi-solid electrolyte with high lithium salt content. The invention also discloses an application of the polyamide semi-solid electrolyte. The fabric has high ionic conductivity.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a polyamide semi-solid electrolyte, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries possess advantages such as high energy density, long shelf life, low self-discharge rate, and suitability for extended driving distances, making them a successfully commercialized energy storage system. The electrolyte in a lithium-ion battery is a liquid mixture of organic solvent and electrolyte salt, with a separator maintaining battery stability. During use, solvent leakage, the generation of flammable gases, and the growth of lithium dendrites inside the battery can easily occur, potentially leading to fires and internal short circuits, resulting in serious safety issues. Currently, solvent-free polymer electrolytes (SPE) and gel polymer electrolytes (GPE) are the most promising new electrolytes for application in novel lithium-ion batteries.

[0003] SPE, also known as solid polymer electrolyte, is a polymer material that typically exhibits high thermal stability, maintaining structural integrity even at high temperatures, resulting in high safety performance. However, compared to GPE, SPE has lower ionic conductivity and poorer mechanical strength, limiting its application range. GPE, on the other hand, is a semi-solid gel-like material composed of a mixture of liquid and non-liquid states, possessing good flexibility and mechanical strength. Its gel structure provides continuous ion channels, and compared to SPE, GPE has higher ionic conductivity, making it suitable for battery systems with high power requirements.

[0004] GPE (Glass-Based Polymer) comprises a polymer matrix, an electrolyte salt, and a liquid solvent as a plasticizer. In this electrolyte, the polymer matrix provides solid-state structural support, while the electrolyte salt plays a crucial role in providing ions within the polymer matrix. GPE embeds the electrolyte salt into the network of the polymer matrix, giving it high ion transport capacity and mechanical strength; the plasticizer enhances ion transport. The cross-linked or network structure of the polymer molecules forms a three-dimensional network structure, with the liquid plasticizer filling the pores. Simultaneously, the ion salt dissolves in both the polymer and the plasticizer, enabling ion conduction. Polyamide can be used as the polymer matrix for GPE; however, polyamide matrices suffer from low solvation capacity for lithium ions, low ionic conductivity, and unstable volume after swelling with electrolyte, leading to poor battery cycle stability. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a polyamide semi-solid electrolyte, its preparation method and application. The polyamide semi-solid electrolyte of the present invention has good ionic conductivity and cycle stability.

[0006] This invention proposes a polyamide semi-solid electrolyte, comprising: polyamide, lithium salt and electrolyte; wherein the polyamide is obtained by polymerization of polyacrylamide, 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1;

[0007] Diamine monomer 1 is at least one of amino-terminated polyethylene glycol and amino-terminated polysiloxane.

[0008] The amino-terminated polyethylene glycol mentioned above can be diamino-terminated polyethylene glycol, with CAS number 24991-53-5; the amino-terminated polysiloxane mentioned above can be diaminopropyl-terminated polydimethylsiloxane, with CAS number 99904-16-2; both can be purchased from the market.

[0009] Preferably, the polyacryl halogen is a mixture of 2,5-furandicarboxylic acid chloride and pyromellitic acid chloride, wherein the molar ratio of 2,5-furandicarboxylic acid chloride to pyromellitic acid chloride is 9.5-9.7:0.3-0.5.

[0010] Preferably, the total molar number of amino groups in 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1 is the same as the molar number of acyl halide groups in the polyacyl halide.

[0011] Preferably, the amino group of diamine monomer 1 accounts for 10-20 mol of the total amino group of 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1.

[0012] The weight-average molecular weight of the above-mentioned polyamides is 10,000-700,000.

[0013] Preferably, the lithium salt is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, or lithium bis(fluorosulfonyl)imide.

[0014] Preferably, the weight ratio of polyamide to lithium salt is 3-4:6-7.

[0015] Preferably, the solute in the electrolyte is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, or lithium bis(fluorosulfonyl)imide.

[0016] Preferably, the solvent of the electrolyte is at least one of ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate.

[0017] The present invention also proposes a method for preparing the above-mentioned polyamide semi-solid electrolyte, comprising the following steps: taking 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1 and polyacrylamide halide in an organic solvent for polymerization reaction, adding proline to remove HCl, and obtaining a polyamide solution; then adding lithium salt to the polyamide solution and mixing to prepare a film; then soaking or wetting the film with electrolyte to obtain a polyamide semi-solid electrolyte with high lithium salt content.

[0018] The reaction is carried out in an inert gas atmosphere; the polymerization reaction is carried out at room temperature.

[0019] Preferably, the organic solvent is N,N-dimethylacetamide.

[0020] Preferably, the weight ratio of the thin film to the electrolyte is 1:2-3.

[0021] The present invention also proposes the application of the above-mentioned polyamide semi-solid electrolyte in lithium batteries.

[0022] This invention uses 2,5-furandicarboxylic acid chloride, trimesoyl chloride, 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine, amino-terminated polyethylene glycol, or amino-terminated polysiloxane as monomers to prepare polyamides. This results in polyamides containing a large number of ether oxygen bonds and an appropriate amount of fluorine, which significantly enhances the solvation and ion transport effects of the polyamide segments on lithium ions, thereby significantly improving the ionic conductivity of the semi-solid electrolyte. Furthermore, the introduction of biphenyl, phenyl, and polysiloxane segments improves the high-temperature resistance of the polyamide. In addition, the introduction of polyethylene glycol or polysiloxane segments and an appropriate amount of trimesoyl chloride improves the mechanical properties of the polyamide film, allowing the film to maintain the stability of its swelling volume after absorbing the electrolyte, thus improving the cycle stability of the semi-solid electrolyte. The introduction of an appropriate amount of fluorine further increases the electrolyte absorption rate, further enhancing the ionic conductivity of the semi-solid electrolyte. Detailed Implementation

[0023] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0024] Example 1

[0025] A polyamide semi-solid electrolyte comprises: polyamide, lithium hexafluorophosphate, and electrolyte; wherein the polyamide is obtained by polymerization of 2,5-furandicarboxyl chloride, pyromellitic tricarboxyl chloride, 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine, and diamine monomer 1;

[0026] Diamine monomer 1 is a diamino-terminated polyethylene glycol;

[0027] The total number of amino groups in 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1 is the same as the number of acyl chloride groups in 2,5-furandicarboxylic acid chloride and pyromellitic acid chloride.

[0028] The molar ratio of 2,5-furandicarboxylic acid chloride to pyromellitic acid chloride is 9.5:0.5;

[0029] The amino group of diamine monomer 1 accounts for 10 mol% of the total amino group of 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1.

[0030] The weight ratio of polyamide to lithium hexafluorophosphate is 4:6;

[0031] The electrolyte is a 1 mol / L lithium hexafluorophosphate solution, and its solvent is an equal volume of ethylene carbonate and methyl ethyl carbonate.

[0032] The preparation method of the above-mentioned polyamide semi-solid electrolyte includes the following steps: In a nitrogen atmosphere, 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine is added to N,N-dimethylacetamide and stirred to dissolve. Then, diamine monomer 1 is added and stirred to dissolve. Then, 2,5-furandicarboxylic acid chloride is added and stirred at room temperature for 15 min. Then, pyromellitic acid chloride is added, and the viscosity of the solution increases until a gel is formed. Then, proline is added and stirred to break the gel, forming a viscous and homogeneous solution. Then, the solution is stirred at room temperature for 4 h. The solid content is adjusted to 10 wt% with N,N-dimethylacetamide to obtain a polyamide solution.

[0033] Lithium hexafluorophosphate was added to the polyamide solution and mixed well. The mixture was then cast into a film and dried to obtain a film with a thickness of 100 μm. The film was cut into circular pieces with a diameter of 20 mm, and the film was soaked in electrolyte for 1 hour. The film was then removed and the residual electrolyte on the surface of the film was wiped dry to obtain a polyamide semi-solid electrolyte. The weight ratio of the film to the electrolyte was 1:2.5.

[0034] Example 2

[0035] A polyamide semi-solid electrolyte comprises: polyamide, lithium bis(trifluoromethanesulfonyl)imide, and an electrolyte; wherein the polyamide is obtained by polymerization of 2,5-furandicarboxyl chloride, pyromellitic tricarboxyl chloride, 4,4'-diamino-2,2'-bis(trifluoromethoxybenzidine) and diamine monomer 1;

[0036] Diamine monomer 1 is a diaminopropyl-terminated polydimethylsiloxane;

[0037] The total number of amino groups in 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1 is the same as the number of acyl chloride groups in 2,5-furandicarboxylic acid chloride and pyromellitic acid chloride.

[0038] The molar ratio of 2,5-furandicarboxylic acid chloride to trimesoyl chloride is 9.7:0.3;

[0039] The amino group of diamine monomer 1 accounts for 20 mol% of the total amino group of 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1.

[0040] The weight ratio of polyamide to lithium bis(trifluoromethanesulfonyl)imide is 3:7;

[0041] The electrolyte is a 1 mol / L lithium bis(trifluoromethanesulfonyl)imide solution, and the solvent is an equal volume of ethylene carbonate and diethyl carbonate.

[0042] The preparation method of the above-mentioned polyamide semi-solid electrolyte includes the following steps: In a nitrogen atmosphere, 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine is added to N,N-dimethylacetamide and stirred to dissolve. Then, diamine monomer 1 is added and stirred to dissolve. Then, 2,5-furandicarboxylic acid chloride is added and stirred at room temperature for 15 min. Then, pyromellitic acid chloride is added, and the viscosity of the solution increases until a gel is formed. Then, proline is added and stirred to break the gel, forming a viscous and homogeneous solution. Then, the solution is stirred at room temperature for 4 h. The solid content is adjusted to 10 wt% with N,N-dimethylacetamide to obtain a polyamide solution.

[0043] Lithium bis(trifluoromethanesulfonyl)imide was added to the polyamide solution and mixed well. The mixture was then cast into a film and dried to obtain a film with a thickness of 100 μm. The film was cut into circular pieces with a diameter of 20 mm, and the film was soaked in electrolyte for 1 h. The film was then removed and the residual electrolyte on the surface of the film was wiped dry to obtain a polyamide semi-solid electrolyte. The weight ratio of the film to the electrolyte was 1:2.4.

[0044] Example 3

[0045] A polyamide semi-solid electrolyte comprises: polyamide, lithium bis(fluorosulfonyl)imide, and an electrolyte; wherein the polyamide is obtained by polymerization of 2,5-furandicarboxyl chloride, pyromellitic tricarboxyl chloride, 4,4'-diamino-2,2'-bis(trifluoromethoxybenzidine) and diamine monomer 1;

[0046] Diamine monomer 1 is a diaminopropyl-terminated polydimethylsiloxane;

[0047] The total number of amino groups in 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1 is the same as the number of acyl chloride groups in 2,5-furandicarboxylic acid chloride and pyromellitic acid chloride.

[0048] The molar ratio of 2,5-furandicarboxylic acid chloride to trimesoyl chloride is 9.6:0.4;

[0049] The amino group of diamine monomer 1 accounts for 15 mol% of the total amino group of 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1.

[0050] The weight ratio of polyamide to lithium bis(fluorosulfonyl)imide is 3.5:6.5;

[0051] The electrolyte is a 1 mol / L lithium bis(fluorosulfonyl)imide solution, and its solvent is an equal volume of ethylene carbonate, dimethyl carbonate and diethyl carbonate.

[0052] The preparation method of the above-mentioned polyamide semi-solid electrolyte includes the following steps: In a nitrogen atmosphere, 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine is added to N,N-dimethylacetamide and stirred to dissolve. Then, diamine monomer 1 is added and stirred to dissolve. Then, 2,5-furandicarboxylic acid chloride is added and stirred at room temperature for 15 min. Then, pyromellitic acid chloride is added, and the viscosity of the solution increases until a gel is formed. Then, proline is added and stirred to break the gel, forming a viscous and homogeneous solution. Then, the solution is stirred at room temperature for 4 h. The solid content is adjusted to 10 wt% with N,N-dimethylacetamide to obtain a polyamide solution.

[0053] Lithium bis(fluorosulfonyl)imide was added to the polyamide solution and mixed well. The mixture was then cast into a film and dried to obtain a film with a thickness of 100 μm. The film was cut into circular pieces with a diameter of 20 mm, and the film was soaked in electrolyte for 1 h. The film was then removed and the residual electrolyte on the surface of the film was wiped dry to obtain a polyamide semi-solid electrolyte. The weight ratio of the film to the electrolyte was 1:2.6.

[0054] Comparative Example 1

[0055] A method for preparing a polyamide semi-solid electrolyte includes the following steps:

[0056] Replace “4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine” with “2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl”, otherwise the same as in Example 3.

[0057] Comparative Example 2

[0058] A method for preparing a polyamide semi-solid electrolyte includes the following steps:

[0059] Replace “diaminopropyl-terminated polydimethylsiloxane” with “4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine”, and make the total molar number of amino groups in 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine the same as the molar number of acyl chloride groups in 2,5-furandicarboxylic acid chloride and pyromellitic tricarboxylic acid chloride, and other aspects are the same as in Example 3.

[0060] Comparative Example 3

[0061] A method for preparing a polyamide semi-solid electrolyte includes the following steps:

[0062] Replace “2,5-furandicarboxylic acid chloride” with “terephthaloyl chloride”, otherwise the same as in Example 3.

[0063] Comparative Example 4

[0064] A method for preparing a polyamide semi-solid electrolyte includes the following steps:

[0065] Replace “pyromellitic tricarboxylic acid chloride” with “2,5-furandicarboxylic acid chloride”, and make the total molar number of amino groups in 4,4'-diamino-2,2'-bis(trifluoromethoxy)benzidine and diamine monomer 1 the same as the molar number of acyl chloride groups in 2,5-furandicarboxylic acid chloride, and other aspects the same as in Example 3.

[0066] The performance of the semi-solid electrolytes prepared in Examples 1-3 and Comparative Examples 1-4 was tested, and the results are shown in Table 1.

[0067] Thermal stability was tested in an N2 atmosphere using thermogravimetric analysis in the range of 80-600℃.

[0068] The method for detecting ionic conductivity is as follows: a semi-solid electrolyte is sandwiched between two stainless steel electrodes (SS) to assemble an SS||ISM||SS ion-barrier battery, its intrinsic resistance R is measured, and the ionic conductivity is calculated according to the formula σ=d / (A*R), where σ is the ionic conductivity, d is the film thickness, and A is the effective area.

[0069] LFP||ISM||Li half-cells were prepared using a semi-solid electrolyte, and their cycle performance was tested.

[0070] Table 1 Test Results

[0071]

[0072] As can be seen from Table 1, the semi-solid electrolyte of the present invention has high ionic conductivity and mechanical properties, and good cycle performance.

[0073] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A polyamide semi-solid electrolyte characterized by, Comprise: Polyamide, lithium salt and electrolyte; wherein the polyamide is obtained by polymerization of polybasic acid halide, 4,4'-diamino-2,2'-bis-trifluoromethoxy benzidine and diamine monomer 1; The diamine monomer 1 is at least one of amino-terminated polyethylene glycol and amino-terminated polysiloxane.

2. The polyamide semi-solid electrolyte of claim 1, wherein, The polybasic acid halide is a mixture of 2,5-furandicarboxylic acid chloride and trimesic acid chloride; preferably, the molar ratio of 2,5-furandicarboxylic acid chloride to trimesic acid chloride is 9.5-9.7:0.3-0.

5.

3. The polyamide semi-solid electrolyte according to claim 1 or 2, wherein, The total molar number of the amino groups of 4,4'-diamino-2,2'-bis-trifluoromethoxy benzidine and diamine monomer 1 is the same as the molar number of the acid halide groups in the polybasic acid halide; preferably, the molar number of the amino groups of diamine monomer 1 accounts for 10-20 mol% of the total molar number of the amino groups of 4,4'-diamino-2,2'-bis-trifluoromethoxy benzidine and diamine monomer 1.

4. The polyamide semi-solid electrolyte according to any one of claims 1 to 3, wherein The lithium salt is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide or lithium bis(fluorosulfonyl)imide; preferably, the weight ratio of the polyamide to the lithium salt is 3-4:6-7.

5. The polyamide semi-solid electrolyte according to any one of claims 1-4, wherein, The solute of the electrolyte is at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide or lithium bis(fluorosulfonyl)imide.

6. The polyamide semi-solid electrolyte according to any one of claims 1-5, wherein, The solvent of the electrolyte is at least one of ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate or diethyl carbonate.

7. A method for producing the polyamide semi-solid electrolyte according to any one of claims 1 to 6, characterized by, The method comprises the following steps: taking 4,4'-diamino-2,2'-bis-trifluoromethoxy benzidine and diamine monomer 1, polybasic acid halide in an organic solvent to carry out polymerization reaction, adding proline to remove HCl to obtain a polyamide solution; then adding lithium salt to the polyamide solution and mixing to prepare a thin film; then soaking or wetting the thin film with an electrolyte to obtain a high-lithium-salt-content polyamide semi-solid electrolyte.

8. The method for preparing the polyamide semi-solid electrolyte according to claim 7, characterized in that, The organic solvent is N,N-dimethylacetamide.

9. The method of claim 7 or 8, wherein the polyamide semi-solid electrolyte is prepared by mixing a polyamide and a lithium salt in a solvent. The weight ratio of the thin film to the electrolyte is 1:2-3.

10. Use of the polyamide semi-solid electrolyte according to any one of claims 1-6 in a lithium battery.

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