A fast-charging type gel polymer electrolyte, preparation thereof and lithium ion battery

Abstract

The present application belongs to the technical field of lithium ion battery gel polymer electrolyte, and provides a fast-charging gel polymer electrolyte, a preparation method thereof and a lithium ion battery. The fast-charging gel polymer electrolyte comprises a support film loaded with a plasticizer and a polymer gel filled in the support film loaded with the plasticizer; the polymer electrolyte is formed by in-situ polymerization of a precursor solution; the precursor solution comprises a multifunctional precursor, an initiator, a plasticizer, a low-binding-energy solvent and a lithium salt; the binding energy between the low-binding-energy solvent and lithium ions is less than or equal to -0.70 eV; and the functionality of the multifunctional precursor is greater than or equal to 3. The fast-charging gel polymer electrolyte effectively balances the safety performance and fast-charging performance of the battery, and the lithium ion battery assembled using the same has high discharge specific capacity and long cycle life under 5C high-rate charging and discharging.

Description

Technical Field

[0001] This invention relates to the field of gel polymer electrolyte technology for lithium-ion batteries, and particularly to a fast-charging gel polymer electrolyte and its preparation, and a lithium-ion battery thereof. Background Technology

[0002] In recent years, with the booming development of portable electronic devices and new energy vehicles, the market has placed higher demands on the performance of lithium-ion batteries in all aspects, especially safety and fast charging capabilities. However, as a key component of lithium-ion batteries, commercial liquid electrolytes pose risks of leakage, combustion, and explosion due to their fluidity and volatility; at the same time, their mechanical strength is insufficient to suppress lithium dendrite growth, easily leading to internal short circuits and thermal runaway. Solid polymer electrolytes do not pose a leakage risk and, due to their excellent mechanical properties, can effectively suppress lithium dendrite growth, possessing the potential to replace liquid electrolytes. However, most polymer solid electrolytes have an ionic conductivity of only 10 at room temperature. -6 -10 -7 Its low S / cm and poor wettability to electrodes, along with its high interfacial impedance, limit its application in lithium-ion batteries.

[0003] Gel polymer electrolytes combine the high ionic conductivity of liquid electrolytes with the high safety of solid electrolytes, making them a promising electrolyte choice for next-generation high-performance battery systems. Gel polymer electrolytes consist of a three-dimensionally cross-linked polymer, a liquid plasticizer, and a lithium salt. The cross-linked polymer network provides good mechanical strength and reduces leakage risk, while the liquid plasticizer ensures high ionic conductivity and good interfacial wettability. However, the fast-charging performance of gel polymer electrolytes needs further improvement. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a fast-charging gel polymer electrolyte, its preparation, and a lithium-ion battery. The fast-charging gel polymer electrolyte provided by this invention has excellent fast-charging performance.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] The present invention provides a fast-charging gel polymer electrolyte, comprising a support membrane loaded with a plasticizing agent, and a polymer gel filled in the support membrane loaded with the plasticizing agent.

[0007] The polymer gel is formed by in-situ polymerization of a precursor solution;

[0008] The precursor solution comprises a low binding energy solvent, a multifunctional precursor, an initiator, a plasticizer, and a lithium salt;

[0009] The binding energy between the low binding energy solvent and lithium ions is less than or equal to -0.70 eV;

[0010] The functionality of the multifunctional precursor is greater than or equal to 3.

[0011] Preferably, the low binding energy solvent is one or more of the following: propyl ether, methyl n-butyl ether, 1-methoxypentane, bis(2,2,2-trifluoroethyl) ether, ethyl fluoroacetate, ethyl difluoroacetate, ethyl trifluoroacetate, trifluoroacetic acid, tetraethyl orthosilicate, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, glutaronitrile, 2-methylmalononitrile, 2-ethylmalononitrile, and adiponitrile.

[0012] Preferably, the multifunctional precursor is one or more of pentaerythritol triacrylate, tri(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane triacrylate, glyceryl trihydroxypropyl ether triacrylate, pentaerythritol tetraacrylate, tetraallyloxyethane, polydipentaerythritol pentaacrylate, and polydipentaerythritol hexaacrylate.

[0013] Preferably, the initiator is one or more of the following: azobisisobutylamidine hydrochloride, dimethyl azobisisobutyrate, azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, dicyclohexyl peroxide, diisopropyl peroxide, lauroyl peroxide, potassium persulfate, and ammonium persulfate.

[0014] Preferably, the plasticizing agent is one or more of lithium difluorophosphate, lithium difluorobis(oxalate)phosphate, lithium nitrate, lithium fluoride, and lithium carbonate.

[0015] Preferably, the plasticizer is one or more of 1,3-dioxolane, 1,4-dioxane, tetrahydrofuran, ethylene carbonate, ethylene carbonate, fluoroethylene carbonate, ethylene sulfate, ethylene sulfite, 1,3-propenesulfonate lactone, succinic acid, dimethyl fluorocarbonate, methylene disulfonate, ethylene carbonate, 1,3-propanesulfonate lactone, propylene sulfite, dimethyl dicarbonate, methyl ethyl fluorocarbonate, diethyl carbonate, methyl ethyl carbonate, sulfolane, and methyl propyl fluorocarbonate.

[0016] Preferably, the lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, and lithium hexafluorophosphate.

[0017] Preferably, the material of the support membrane is one or more of glass fiber, polyethylene, polypropylene and cellulose.

[0018] This invention also provides a method for preparing the fast-charging gel polymer electrolyte described in the above technical solution, comprising the following steps:

[0019] The support membrane is immersed in a plasticizing agent solution, and the solvent is removed to obtain a support membrane loaded with plasticizing agent.

[0020] A precursor solution is obtained by mixing a multifunctional precursor, a plasticizer, a low binding energy solvent, a lithium salt, and an initiator.

[0021] The precursor solution is dropped onto the support membrane loaded with the plasticizing agent to obtain a support membrane wetted by the precursor solution and loaded with the plasticizing agent.

[0022] The precursor solution-wetted support membrane loaded with a plasticizing agent is subjected to in-situ polymerization to obtain the fast-charging gel polymer electrolyte.

[0023] The present invention also provides a lithium-ion battery, comprising a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte is the fast-charging gel polymer electrolyte described in the above technical solution or the fast-charging gel polymer electrolyte prepared by the preparation method described in the above technical solution.

[0024] This invention provides a fast-charging gel polymer electrolyte.

[0025] The fast-charging gel polymer electrolyte of this invention is prepared by thermally initiated in-situ polymerization of a precursor solution and consists of a polymer backbone, a plasticizer, a low binding energy solvent, a film-forming agent, a lithium salt, and a supporting film. The polymer backbone is formed by in-situ polymerization of multifunctional precursors initiated by an initiator. Due to steric hindrance, the polymer backbone contains a large number of unsaturated double bonds remaining from incomplete polymerization of multifunctional precursors. During battery charging and discharging, these residual unsaturated double bonds can undergo polymerization reactions on the electrode surface, forming a highly cross-linked electrode / electrolyte interface layer connected to the polymer backbone. This interface layer has high mechanical strength and elasticity, is insoluble, and can exist stably for a long time, avoiding electrolyte consumption caused by long-term interface layer repair. The low binding energy solvent has a low binding energy between lithium ions, which is beneficial for rapid lithium ion transport, thus giving the fast-charging gel polymer electrolyte a high lithium ion transport number. The film-forming agent can generate an inorganic-rich electrode / electrolyte interface layer on the electrode surface, improving the ionic conductivity of the interface layer and enhancing the interfacial transport capability of lithium ions. The fast-charging gel polymer electrolyte of the present invention effectively balances the safety performance and fast-charging performance of the battery. Lithium-ion batteries assembled using it have high discharge specific capacity and long cycle life under 5C high-rate charge and discharge.

[0026] The present invention also provides a method for preparing the fast-charging gel polymer electrolyte described in the above technical solution. The solubility of the film-forming agent in the precursor solution is limited. By pre-impregnation, it is uniformly dispersed on the support film, which ensures that the local concentration of the film-forming agent in the fast-charging gel polymer electrolyte is uniform and avoids uneven film formation on the electrode surface and blockage of the support film pores caused by poor dissolution and dispersion. Attached Figure Description

[0027] Figure 1 The figure shows the chronocurrent curve of the fast-charging gel polymer electrolyte lithium metal|| lithium metal battery of Example 1, and the inset shows the electrochemical impedance spectroscopy before and after polarization.

[0028] Figure 2 The inset shows the chronoamperometry curves of the lithium metal || lithium metal battery with gel polymer electrolyte in Comparative Example 1. The inset shows the electrochemical impedance spectroscopy before and after polarization.

[0029] Figure 3 SEM image of the lithium metal electrode of the fast-charging gel polymer electrolyte lithium iron phosphate battery after 100 cycles;

[0030] Figure 4 SEM image of the lithium metal electrode of the lithium iron phosphate battery with gel polymer electrolyte in Comparative Example 3 after 100 cycles.

[0031] Figure 5 The graph shows a comparison of the cycle performance of lithium metal / lithium iron phosphate batteries using the fast-charging gel polymer electrolyte of Example 1 and the gel polymer electrolytes of Comparative Examples 5 and 6. Detailed Implementation

[0032] The present invention provides a fast-charging gel polymer electrolyte, comprising a support membrane loaded with a plasticizing agent, and a polymer gel filled in the support membrane loaded with the plasticizing agent.

[0033] The polymer gel is formed by in-situ polymerization of a precursor solution;

[0034] The precursor solution comprises a low binding energy solvent, a multifunctional precursor, an initiator, a plasticizer, and a lithium salt;

[0035] The binding energy between the low binding energy solvent and lithium ions is less than or equal to -0.70 eV;

[0036] The functionality of the multifunctional precursor is greater than or equal to 3.

[0037] Unless otherwise specified, the raw materials used in this invention are preferably commercially available products.

[0038] The fast-charging gel polymer electrolyte provided by this invention includes a supporting membrane loaded with a film-forming agent. In this invention, the film-forming agent is preferably one or more of lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium nitrate, lithium fluoride, and lithium carbonate, and more preferably lithium difluorophosphate, lithium nitrate, lithium fluoride, or lithium carbonate. In this invention, the material of the supporting membrane is preferably one or more of glass fiber, polyethylene, polypropylene, and cellulose.

[0039] The fast-charging gel-type polymer electrolyte provided by this invention comprises a polymer gel filled in a support membrane loaded with a plasticizer. In this invention, the polymer gel is formed by in-situ polymerization of a precursor solution. In this invention, the precursor solution comprises a low binding energy solvent, a multifunctional precursor, an initiator, a plasticizer, and a lithium salt. In this invention, the functionality of the multifunctional precursor is greater than or equal to 3. In this invention, the multifunctional precursor is preferably one or more of pentaerythritol triacrylate, tri(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane triacrylate, glycerol trihydroxypropyl ether triacrylate, pentaerythritol tetraacrylate, tetraallyloxyethane, polydipentaerythritol pentaacrylate, and polydipentaerythritol hexaacrylate. In this invention, the initiator is preferably one or more of azobisisobutyranin hydrochloride, dimethyl azobisisobutyrate, azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, dicyclohexyl percarbonate, diisopropyl percarbonate, lauroyl peroxide, potassium persulfate, and ammonium persulfate. In this invention, the binding energy between the low binding energy solvent and lithium ions is less than or equal to -0.70 eV, specifically preferably -0.69 eV, -0.68 eV, -0.65 eV, -0.58 eV, -0.57 eV, -0.56 eV, -0.54 eV, -0.52 eV, or -0.45 eV; where the "-" in -0.70 eV indicates that the binding process between lithium ions and the solvent is exothermic; when comparing the binding energy between the low binding energy solvent and lithium ions, the absolute value is considered.

[0040] In this invention, the low binding energy solvent is preferably one or more of the following: propyl ether, methyl n-butyl ether, 1-methoxypentane, bis(2,2,2-trifluoroethyl) ether, ethyl fluoroacetate, ethyl difluoroacetate, ethyl trifluoroacetate, trifluoroacetic acid, tetraethyl orthosilicate, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, glutaronitrile, 2-methylmalononitrile, 2-ethylmalononitrile, and adiponitrile. In this invention, the plasticizer is preferably one or more of 1,3-dioxolane, 1,4-dioxane, tetrahydrofuran, ethylene carbonate, ethylene carbonate, fluoroethylene carbonate, ethylene sulfate, ethylene sulfite, 1,3-propenesulfonate lactone, succinic acid, dimethyl fluorocarbonate, methylene disulfonate, ethylene ethylene carbonate, 1,3-propanesulfonate lactone, propylene sulfite, dimethyl dicarbonate, methyl ethyl fluorocarbonate, diethyl carbonate, methyl ethyl carbonate, sulfolane, and methyl propyl fluorocarbonate. In this invention, the lithium salt is preferably one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, and lithium hexafluorophosphate. In this invention, the mass ratio of the multifunctional precursor to the initiator in the precursor solution is preferably 1:0.001 to 0.1, specifically preferably 1:0.001, 1:0.005, 1:0.0067, 1:0.01, 1:0.0125, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, or 1:0.1. In this invention, the mass ratio of the multifunctional precursor to the plasticizer is preferably 1:1 to 3, specifically preferably 1:1, 1:1.25, 1:1.4, 1:1.5, 1:2, 1:2.5, or 1:3. In this invention, the mass ratio of the multifunctional precursor to the low binding energy solvent is preferably 1:8 to 14, specifically preferably 1:8, 1:9, 1:10, 1:11, 1:12, 1:12.5, 1:13, or 1:14. In this invention, the mass ratio of the multifunctional precursor to the lithium salt is preferably 1:1 to 5, specifically preferably 1:1, 1:1.6, 1:1.7, 1:1.75, 1:2, 1:3, 1:4, or 1:5.

[0041] In this invention, the multifunctional precursor in the precursor solution is polymerized in situ under the action of an initiator to form a polymer backbone; plasticizer, low binding energy solvent and lithium salt are dispersed in the polymer backbone.

[0042] In this invention, the fast-charging gel polymer electrolyte includes a support membrane and active ingredients loaded on the support membrane; the active ingredients include the following components in mass percentage: polymer backbone 1~80%, plasticizer 1~20%, low binding energy solvent 1~80%, film-forming agent 1~20%, lithium salt 5~50%.

[0043] In this invention, the preferred mass percentage of the polymer backbone in the active ingredient is 1%, 5%, 5.44%, 5.85%, 7.46%, 8.04%, 8.70%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%.

[0044] In this invention, the preferred mass percentage of plasticizer in the active ingredient is 1%, 5%, 8.70%, 9.33%, 10%, 11.25%, 11.70%, 15%, 16.30%, or 20%.

[0045] In this invention, the mass percentage of the low binding energy solvent in the active ingredient is preferably 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65.22%, 64.31%, 65%, 67.16%, 69.56%, 70%, 73.10%, 75%, or 80%.

[0046] In this invention, the preferred mass percentage of the plasticizing agent in the active ingredient is 1%, 2.17%, 2.99%, 3.50%, 3.54%, 4.34%, 5%, 10%, 15%, or 20%.

[0047] In this invention, the preferred mass percentage of lithium salt in the active ingredient is 5%, 5.85%, 8.70%, 10%, 10.87%, 12.86%, 13.06%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.

[0048] This invention also provides a method for preparing the fast-charging gel polymer electrolyte described in the above technical solution, comprising the following steps:

[0049] The support membrane is immersed in a plasticizing agent solution, and the solvent is removed to obtain a support membrane loaded with plasticizing agent.

[0050] A precursor solution is obtained by mixing a multifunctional precursor, a plasticizer, a low binding energy solvent, a lithium salt, and an initiator.

[0051] The precursor solution is dropped onto the support membrane loaded with the plasticizing agent to obtain a support membrane wetted by the precursor solution and loaded with the plasticizing agent.

[0052] The precursor solution-wetted support membrane loaded with a plasticizing agent is subjected to in-situ polymerization to obtain the fast-charging gel polymer electrolyte.

[0053] In this invention, a support film is immersed in a plasticizing agent solution, and the solvent is removed to obtain a support film loaded with a plasticizing agent.

[0054] In one specific embodiment of the present invention, the shape of the support membrane is preferably cylindrical, the diameter of the cylinder is preferably 16.000 mm, and the thickness is preferably 0.160 mm.

[0055] In this invention, the concentration of the plasticizing agent in the plasticizing agent solution is preferably 0.05~0.50 g / mL, specifically preferably 0.05 g / mL, 0.1 g / mL, 0.15 g / mL, 0.2 g / mL, 0.25 g / mL, 0.3 g / mL, 0.35 g / mL, 0.4 g / mL, 0.45 g / mL, or 0.50 g / mL. In this invention, the solvent in the plasticizing agent solution preferably includes one or more of acetone, methanol, ethanol, and isopropanol. In this invention, the impregnation time is preferably 5~15 min, more preferably 10 min. In this invention, the solvent removal method is preferably vacuum drying, and the vacuum drying temperature is preferably 40~120℃, specifically preferably 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, or 120℃; this invention does not specifically limit the vacuum drying time, as long as the solvent is removed.

[0056] This invention mixes a multifunctional precursor, a plasticizer, a low binding energy solvent, a lithium salt, and an initiator to obtain a precursor solution. This invention does not specifically limit the mixing method of the multifunctional precursor, plasticizer, low binding energy solvent, lithium salt, and initiator, as long as the above materials can be mixed. In this invention, the preferred ratio of each substance in the precursor solution is consistent with the above-described technical solution, and will not be repeated here.

[0057] After obtaining the support film loaded with the plasticizing agent and the precursor solution, the present invention drops the precursor solution onto the support film loaded with the plasticizing agent to obtain a support film wetted by the precursor solution and loaded with the plasticizing agent.

[0058] In this invention, after the precursor solution is dropped onto the support membrane loaded with the plasticizing agent, the precursor solution fully wets the support membrane loaded with the plasticizing agent through capillary action.

[0059] In this invention, the amount of precursor solution added is preferably such that the support membrane loaded with the plasticizing agent is fully wetted, but no excess precursor solution is lost; at the same time, the precursor solution has limited solubility for the plasticizing agent, and can only dissolve a small portion of the plasticizing agent loaded on the support membrane, while most of the plasticizing agent remains uniformly distributed on the support membrane and continues to dissolve during battery cycling as the dissolved plasticizing agent is consumed.

[0060] In one specific embodiment of the present invention, a cylindrical support membrane with a diameter of 16.000 mm and a thickness of 0.160 mm is impregnated with 0.08 mL of precursor solution.

[0061] After obtaining a support membrane wetted with a precursor solution and loaded with a plasticizing agent, the present invention further polymerizes the support membrane wetted with the precursor solution and loaded with a plasticizing agent in situ to obtain the fast-charging gel polymer electrolyte.

[0062] In this invention, the in-situ polymerization temperature is preferably 40~100℃, specifically preferably 40℃, 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃; the time is preferably 0.5~12h, specifically preferably 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h or 12h.

[0063] In one specific embodiment of the present invention, the in-situ polymerization is preferably carried out during the battery assembly process.

[0064] The present invention also provides a lithium-ion battery, comprising a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte is the fast-charging gel polymer electrolyte described in the above technical solution or the fast-charging gel polymer electrolyte prepared by the preparation method described in the above technical solution.

[0065] The lithium-ion battery provided by the present invention includes a positive electrode, wherein the active material of the positive electrode is preferably one of lithium iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-rich manganese-based positive electrode materials.

[0066] The lithium-ion battery provided by the present invention includes a negative electrode, which is preferably one of artificial graphite, natural graphite, hard carbon, mesophase carbon microspheres, silicon-carbon negative electrode, lithium titanate, and metallic lithium.

[0067] The lithium-ion battery provided by the present invention includes an electrolyte, wherein the electrolyte is the fast-charging gel polymer electrolyte described in the above technical solution or the fast-charging gel polymer electrolyte prepared by the preparation method described in the above technical solution.

[0068] In this invention, the method for preparing the lithium-ion battery preferably includes the following steps:

[0069] A support membrane, wetted with a precursor solution and loaded with a plasticizing agent, is assembled into the structure of a lithium-ion battery, and then in-situ polymerization is performed to obtain the lithium-ion battery.

[0070] In this invention, the assembly of other components in the structure of the lithium-ion battery can be carried out in accordance with operations well known to those skilled in the art.

[0071] In this invention, the parameters of the in-situ polymerization are preferably the same as those described above, and will not be repeated here.

[0072] The following detailed description, in conjunction with embodiments, illustrates the fast-charging gel polymer electrolyte and its preparation, as well as the lithium-ion battery provided by this invention. However, these descriptions should not be construed as limiting the scope of protection of this invention.

[0073] Example 1

[0074] A glass fiber support membrane with a thickness of 0.160 mm and a diameter of 16.000 mm was immersed in an acetone solution of lithium difluorophosphate with a concentration of 0.20 g / mL. After 10 min, it was removed and then placed in a vacuum dryer at 80 °C for 24 h to remove the solvent.

[0075] Trimethylolpropane triacrylate (0.20 g), methyltriethoxysilane (2.50 g, with a binding energy of -0.56 eV with lithium ions), vinylene carbonate (0.40 g), lithium bis(trifluoromethanesulfonylimide) (0.20 g), and azobisisobutyronitrile (0.001 g) were mixed and stirred until homogeneous to obtain a precursor solution.

[0076] 0.08 mL of precursor solution was dropped onto a support membrane loaded with lithium difluorophosphate to obtain a support membrane wetted with precursor solution and loaded with lithium difluorophosphate. Subsequently, in-situ polymerization was performed using this support membrane wetted with precursor solution and loaded with lithium difluorophosphate to obtain a fast-charging gel polymer electrolyte and a battery assembled using the fast-charging gel polymer electrolyte. The obtained fast-charging gel polymer electrolyte includes a support membrane and active components loaded on the support membrane. The active components include the following components by mass percentage: polymer backbone 5.85%, plasticizer 11.70%, low binding energy solvent 73.10%, film-forming agent 3.50%, and lithium salt 5.85%.

[0077] Example 2

[0078] The only difference from Example 1 is that the multifunctional precursor trimethylolpropane triacrylate is replaced with glycerol trihydroxypropyl ether triacrylate; otherwise, the same as in Example 1.

[0079] Example 3

[0080] The only difference from Example 1 is that the multifunctional precursor trimethylolpropane triacrylate is replaced with tetraallyloxyethane; otherwise, the same as in Example 1.

[0081] Example 4

[0082] The only difference from Example 1 is that the low binding energy solvent methyltriethoxysilane is replaced with methyl n-butyl ether (with a binding energy of -0.58 eV with lithium ions), while the rest is the same as Example 1.

[0083] Example 5

[0084] The only difference from Example 1 is that the low binding energy solvent methyltriethoxysilane is replaced with 1-methoxypentane (with a binding energy of -0.45 eV with lithium ions), otherwise the same as Example 1.

[0085] Example 6

[0086] The only difference from Example 1 is that the low binding energy solvent methyltriethoxysilane is replaced with ethyl trifluoroacetate (with a binding energy of -0.69 eV with lithium ions), while the rest is the same as Example 1.

[0087] Example 7

[0088] The only difference from Example 1 is that the low binding energy solvent methyltriethoxysilane is replaced with 2-methylmalononitrile (with a binding energy of -0.54 eV with lithium ions), while the rest is the same as Example 1.

[0089] Example 8

[0090] A glass fiber support membrane with a thickness of 0.160 mm and a diameter of 16.000 mm was immersed in a methanol solution of lithium nitrate with a concentration of 0.20 g / mL. After 10 min, it was removed and then vacuum dried at 80 °C for 24 h to remove the solvent.

[0091] Pentaerythritol triacrylate (0.25 g), propyl ether (2.00 g, with a binding energy of -0.68 eV with lithium ions), ethylene carbonate (0.35 g), lithium bis(fluorosulfonyl)imide (0.4 g), and azobisisoheptanenitrile (0.005 g) were mixed and stirred until homogeneous to obtain a precursor solution.

[0092] 0.08 mL of precursor solution was dropped onto a lithium nitrate-loaded support membrane to obtain a precursor solution-wetted support membrane loaded with lithium nitrate. Subsequently, in-situ polymerization was performed using this precursor solution-wetted lithium nitrate-loaded support membrane to obtain a fast-charging gel polymer electrolyte and a battery assembled using the fast-charging gel polymer electrolyte. The obtained fast-charging gel polymer electrolyte includes a support membrane and active components loaded on the support membrane. The active components include the following components by mass percentage: polymer backbone 8.04%, plasticizer 11.25%, low binding energy solvent 64.31%, film-forming agent 3.54%, and lithium salt 12.86%.

[0093] Example 9

[0094] A glass fiber support membrane with a thickness of 0.160 mm and a diameter of 16.000 mm was immersed in an isopropanol solution of lithium difluorophosphate with a concentration of 0.40 g / mL. After 10 min, it was removed and then vacuum dried at 80 °C for 24 h to remove the solvent.

[0095] Tris(2-hydroxyethyl)isocyanurate triacrylate (0.30 g), adiponitrile (0.70 g, with a binding energy of -0.57 eV with lithium ions), vinylene carbonate (0.30 g), lithium perchlorate (0.50 g), and azobisisobutyronitrile (0.002 g) were mixed and stirred until homogeneous to obtain a precursor solution.

[0096] 0.08 mL of precursor solution was dropped onto a support membrane loaded with lithium difluorophosphate to obtain a support membrane wetted by the precursor solution and loaded with lithium difluorophosphate.

[0097] Subsequently, in-situ polymerization was carried out using a support film wetted with the precursor solution and loaded with lithium difluorophosphate to obtain a fast-charging gel polymer electrolyte and a battery assembled using the fast-charging gel polymer electrolyte. The obtained fast-charging gel polymer electrolyte includes a support film and active components loaded on the support film. The active components include the following components in mass percentage: polymer backbone 15.00%, plasticizer 15.00%, low binding energy solvent 35.00%, film-forming agent 10.00%, and lithium salt 25.00%.

[0098] Example 10

[0099] A polyethylene support membrane with a thickness of 0.025 mm and a diameter of 16.000 mm was immersed in a methanol solution of lithium nitrate with a concentration of 0.50 g / mL. After 10 min, it was removed and then vacuum dried at 80 °C for 24 h to remove the solvent.

[0100] The precursor solution was obtained by mixing and stirring pentaerythritol tetraacrylate (0.20 g), fluoroacetonitrile (1.60 g, with a binding energy of -0.69 eV with lithium ions), fluoroethylene carbonate (0.20 g), lithium bis(trifluoromethanesulfonyl)imide (0.20 g), and azobisisoheptanenitrile (0.005 g).

[0101] 0.08 mL of precursor solution was dropped onto a lithium nitrate-loaded support membrane to obtain a precursor solution-wetted lithium nitrate-loaded support membrane. Subsequently, in-situ polymerization was performed using this precursor solution-wetted lithium nitrate-loaded support membrane to obtain a fast-charging gel polymer electrolyte and a battery assembled using the fast-charging gel polymer electrolyte. The obtained fast-charging gel polymer electrolyte includes a support membrane and active components loaded on the support membrane. The active components include the following components by mass percentage: polymer backbone 8.70%, plasticizer 8.70%, low binding energy solvent 69.56%, film-forming agent 4.34%, and lithium salt 8.70%.

[0102] Example 11

[0103] A polypropylene support membrane with a thickness of 0.025 mm and a diameter of 16.000 mm was immersed in an ethanol solution of lithium fluoride with a concentration of 0.40 g / mL. After 10 min, it was removed and then vacuum dried at 80 °C for 24 h to remove the solvent.

[0104] Tetraenepropoxyethane (0.20 g), tetraethyl orthosilicate (1.80 g, with a binding energy of -0.52 eV with lithium ions), succinic acid (0.25 g), lithium hexafluorophosphate (0.35 g), and benzoyl peroxide (0.005 g) were mixed and stirred until homogeneous to obtain a precursor solution.

[0105] 0.08 mL of precursor solution was dropped onto a lithium fluoride-loaded support film to obtain a precursor solution-wetted lithium fluoride-loaded support film. Subsequently, in-situ polymerization was performed using this precursor solution-wetted lithium fluoride-loaded support film to obtain a fast-charging gel polymer electrolyte and a battery assembled using the fast-charging gel polymer electrolyte. The obtained fast-charging gel polymer electrolyte includes a support film and active components loaded on the support film. The active components include the following components by mass percentage: polymer backbone 7.46%, plasticizer 9.33%, low binding energy solvent 67.16%, film-forming agent 2.99%, and lithium salt 13.06%.

[0106] Example 12

[0107] A cellulose support membrane with a thickness of 0.025 mm and a diameter of 16.000 mm was immersed in an acetone solution of lithium carbonate with a concentration of 0.30 g / mL. After 10 min, it was removed and then vacuum dried at 80 °C for 24 h to remove the solvent.

[0108] Poly(dipentaerythritol) pentaacrylate (0.20 g), ethyl difluoroacetate (2.40 g, with a binding energy of -0.65 eV with lithium ions), ethyl methyl carbonate (0.60 g), lithium perchlorate (0.40 g), and azobisisobutyronitrile (0.005 g) were mixed and stirred until homogeneous to obtain a precursor solution.

[0109] 0.08 mL of precursor solution was dropped onto a lithium carbonate-loaded support film to obtain a precursor solution-wetted lithium carbonate-loaded support film. Subsequently, in-situ polymerization was performed using this precursor solution-wetted lithium carbonate-loaded support film to obtain a fast-charging gel polymer electrolyte and a battery assembled using the fast-charging gel polymer electrolyte. The obtained fast-charging gel polymer electrolyte includes a support film and active components loaded on the support film. The active components include the following components by mass percentage: polymer backbone 5.44%, plasticizer 16.30%, low binding energy solvent 65.22%, film-forming agent 2.17%, and lithium salt 10.87%.

[0110] Comparative Example 1

[0111] The only difference from Example 1 is that the low binding energy solvent methyltriethoxysilane is replaced with the high binding energy solvent tetraethylene glycol dimethyl ether (with a binding energy of -1.76 eV with lithium ions), otherwise it is the same as Example 1.

[0112] Comparative Example 2

[0113] The only difference from Example 1 is that the low binding energy solvent methyltriethoxysilane is replaced with the high binding energy solvent ethylene glycol dimethyl ether (with a binding energy of -1.54 eV with lithium ions), otherwise it is the same as Example 1.

[0114] Comparative Example 3

[0115] The only difference from Example 1 is that the multifunctional precursor trimethylolpropane triacrylate is replaced with the difunctional precursor ethylene glycol diacrylate; otherwise, they are the same as in Example 1.

[0116] Comparative Example 4

[0117] The only difference from Example 1 is that the multifunctional precursor trimethylolpropane triacrylate is replaced with the monofunctional precursor acrylate; otherwise, it is the same as Example 1.

[0118] Comparative Example 5

[0119] The only difference from Example 1 is that the low binding energy solvent methyltriethoxysilane is replaced with the high binding energy solvent tetraethylene glycol dimethyl ether, and the multifunctional precursor trimethylolpropane triacrylate is replaced with the monofunctional precursor acrylate. The rest is the same as in Example 1.

[0120] Comparative Example 6

[0121] A glass fiber support membrane with a thickness of 0.160 mm and a diameter of 16.000 mm was immersed in acetone for 10 minutes, then removed and vacuum dried at 80°C for 24 hours to remove the solvent.

[0122] Trimethylolpropane triacrylate (0.20 g), methyltriethoxysilane (2.50 g, with a binding energy of -0.56 eV with lithium ions), vinylene carbonate (0.40 g), lithium bis(trifluoromethanesulfonylimide) (0.20 g), azobisisobutyronitrile (0.001 g), and lithium difluorophosphate (0.12 g) were mixed and stirred to obtain the precursor system.

[0123] 0.08 mL of the precursor system was dropped onto the support membrane to obtain a support membrane wetted with the precursor system. Subsequently, in-situ polymerization was performed using this precursor-wetted support membrane to obtain a gel polymer electrolyte and a battery assembled using the gel polymer electrolyte. Other operations were the same as in Example 1.

[0124] Application examples

[0125] CR2032 button cells were assembled using precursor solution-wetted support films loaded with plasticizing agents from Examples 1-12 and Comparative Examples 1-6. The cell assembly was performed in an argon-filled glove box. A stainless steel gasket, negative electrode, and precursor solution-wetted support film loaded with plasticizing agent were sequentially placed into the negative electrode shell, followed by the positive electrode sheet, stainless steel gasket, stainless steel spring sheet, and positive electrode shell. Finally, the cells were sealed using a sealing machine, and the cells were subjected to in-situ polymerization at 40-100°C for 0.5-12 hours. The positive electrode sheet was prepared as follows: 0.80g of positive electrode active material, 0.10g of carbon black, 0.10g of polyvinylidene fluoride, and 2.00g of N-methylpyrrolidone were mixed and stirred for 48 hours to form a viscous slurry. The slurry was coated onto aluminum foil and vacuum dried at 100°C for 12 hours to obtain a positive electrode active material with an areal density of approximately 2mg / cm³. 2 The positive electrode sheet.

[0126] The tests conducted on Examples 1-12 and Comparative Examples 1-6 are as follows:

[0127] 1. Lithium-ion transference number was determined using the Abraham method. A battery with lithium metal as both positive and negative electrodes was assembled, and electrochemical impedance spectroscopy (EIS) was first performed on an electrochemical workstation at Princeton, with a frequency range of 10⁻⁶. -2 -10 6 The impedance before polarization was obtained by measuring the frequency Hz; then, a chronoamperometry test was performed at a voltage of 10mV for 3000s to obtain the polarization current; finally, an electrochemical impedance spectroscopy test was performed again at a frequency range of 10 Hz. -2-10 6 The Hz value is used to obtain its polarized impedance. The lithium-ion transport number is calculated using Formula 1.

[0128] Formula 1;

[0129] In formula 1, Represents the lithium-ion transference number; Represents steady-state current, measured in amperes (A). Represents polarization voltage, measured in V; This represents the initial current, measured in amperes (A). Represents the impedance before polarization, in Ω; This represents the impedance after polarization, and the unit is Ω.

[0130] 2. The surface morphology of the lithium metal electrode after battery cycling was observed using a scanning electron microscope. A CR2032 battery with a lithium iron phosphate positive electrode and a lithium metal negative electrode was assembled and subjected to 100 charge-discharge cycles at 5C rate using a Blue Battery Cycling System (CT2001A) at 25°C. After 100 cycles, the battery was disassembled, and the lithium metal electrode was obtained. Its surface morphology was observed using a scanning electron microscope.

[0131] 3. Charge-discharge cycle performance test. Assemble a CR2032 battery with lithium iron phosphate positive electrode and lithium metal negative electrode, and conduct a 5C rate charge-discharge cycle test on the battery at 25℃ using the Blue Battery Cycling System (CT2001A).

[0132] The results of the tests, including lithium-ion transference number, electrode surface morphology, maximum discharge specific capacity, discharge specific capacity after 1000 cycles, and capacity retention rate after 1000 cycles, are shown in Table 1.

[0133] Table 1. Lithium-ion transference number, electrode surface morphology after battery cycling, and long-cycle performance of different electrolytes.

[0134]

[0135]

[0136] As shown in Table 1, Examples 1-12, Comparative Examples 3 and 4 all contained low-binding-energy solvents, resulting in lithium-ion transference numbers exceeding 0.50; while Comparative Examples 1, 2, and 5 did not contain low-binding-energy solvents, and their lithium-ion transference numbers were all less than 0.50. After 1000 charge-discharge cycles at a high rate of 5C, the lithium metal / lithium iron phosphate batteries assembled with each electrolyte showed that Examples 1-12, Comparative Examples 1 and 2, containing polymer backbones formed by the polymerization of multifunctional precursors, were able to form a dense and uniform interface layer on the electrode surface, with no obvious interface byproducts. In contrast, Comparative Examples 3, 4, and 5 did not contain polymer backbones formed by the polymerization of multifunctional precursors, and none of them formed a stable interface layer on the electrode surface. The electrode surfaces exhibited obvious pores and cracks, and a large number of byproducts were present. Examples 1-12, by pre-depositing the plasticizing agent onto the support film and ensuring its uniform distribution, guarantee a uniform local concentration of the agent within the fast-charging gel polymer electrolyte. This results in the formation of a dense and uniform interface layer on the electrode surface during cycling, significantly improving the battery's cycle life. In contrast, in Comparative Example 6, poor dissolution and dispersion of the plasticizing agent led to uneven film formation on the electrode surface and blockage of the support film pores, subsequently causing impaired lithium-ion transport and local current density imbalance, ultimately triggering lithium dendrite growth and capacity decay. Compared to the lithium metal / lithium iron phosphate batteries assembled using Comparative Examples 1-6, the lithium metal / lithium iron phosphate batteries assembled using Examples 1-12 exhibit a higher maximum discharge specific capacity and higher discharge specific capacity and capacity retention after 1000 cycles.

[0137] Figure 1 The inset shows the chronoamperometry curves of the fast-charging gel polymer electrolyte lithium metal||lithium metal battery of Example 1, with the electrochemical impedance spectroscopy before and after polarization shown in the inset. Figure 1 It can be seen that the lithium-ion transference number of the fast-charging gel polymer electrolyte is 0.84.

[0138] Figure 2 The inset shows the chronoamperometry curves of the lithium metal || lithium metal battery with gel polymer electrolyte in Comparative Example 1. The inset also shows the electrochemical impedance spectroscopy before and after polarization. Figure 2 It can be seen that the lithium-ion transference number of the gel polymer electrolyte is 0.38.

[0139] Figure 3 This is a SEM image of the lithium metal electrode of the fast-charging gel polymer electrolyte lithium iron phosphate battery of Example 1 after 100 cycles. Figure 3 It can be seen that a dense and uniform interface layer is formed on the surface of the lithium metal electrode, and there are no obvious interface byproducts on the electrode surface.

[0140] Figure 4The image shows a SEM image of the lithium metal electrode in the gel polymer electrolyte of Comparative Example 3 after 100 cycles of a lithium metal / lithium iron phosphate battery. Figure 4 It can be seen that a stable interface layer has not been formed on the surface of the lithium metal electrode, and the electrode surface has obvious pores and cracks, as well as a large number of by-products.

[0141] Figure 5 This is a comparison chart of the cycle performance of lithium metal / lithium iron phosphate batteries using the fast-charging gel polymer electrolyte of Example 1 and the gel polymer electrolytes of Comparative Examples 5 and 6. Figure 5 It can be seen that compared with the lithium metal / lithium iron phosphate batteries assembled using Comparative Examples 5 and 6, the lithium metal / lithium iron phosphate battery assembled using Example 1 has a higher maximum discharge specific capacity, and also exhibits higher discharge specific capacity and capacity retention after 1000 cycles. The fast-charging gel polymer electrolyte in Example 1 contains a polymer backbone formed by the polymerization of a low-binding-energy solvent and a multifunctional precursor, and the plasticizer has a uniform concentration in all its local areas, ensuring excellent lithium-ion transport capability and enabling the formation of a dense, uniform, and stable interface layer on the electrode surface, thereby achieving long-term stable cycling at high rates. Comparative Example 5 does not contain a polymer backbone formed by the polymerization of low binding energy solvents and multifunctional precursors, resulting in limited lithium-ion transport capacity and the inability to form a stable interface layer on the electrode surface, generating a large number of interface by-products, which in turn leads to rapid capacity decay of the battery. In Comparative Example 6, poor dissolution and dispersion of the plasticizing agent caused uneven film formation on the electrode surface and blockage of the pores of the supporting film, which in turn led to impaired lithium-ion transport and local current density imbalance, ultimately resulting in lithium dendrite growth and battery capacity decay.

[0142] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fast-charging gel polymer electrolyte, characterized in that, Includes a support film loaded with a plasticizing agent, and a polymer gel filled in the support film loaded with the plasticizing agent; The polymer gel is formed by in-situ polymerization of a precursor solution; The precursor solution comprises a low binding energy solvent, a multifunctional precursor, an initiator, a plasticizer, and a lithium salt; The binding energy between the low binding energy solvent and lithium ions is less than or equal to -0.70 eV; The functionality of the multifunctional precursor is greater than or equal to 3; The low binding energy solvent is one or more of the following: propyl ether, methyl n-butyl ether, 1-methoxypentane, ethyl difluoroacetate, ethyl trifluoroacetate, tetraethyl orthosilicate, methyltriethoxysilane, fluoroacetonitrile, 2-methylmalononitrile, and adiponitrile. The multifunctional precursor is one or more of pentaerythritol triacrylate, tri(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, tetraallyloxyethane, and polydipentaerythritol pentaacrylate. The plasticizing agent is one or more of lithium difluorophosphate, lithium nitrate, lithium fluoride, or lithium carbonate; The initiator is one or more of azobisisobutyronitrile and azobisisoheptanenitrile; The plasticizer is one or more of ethylene carbonate, vinylene carbonate, and fluoroethylene carbonate; The lithium salt is one or more of lithium bis(trifluoromethanesulfonylimide) and lithium bis(fluorosulfonylimide); The material of the support membrane is one or more of glass fiber, polyethylene, polypropylene and cellulose; The mass ratio of the multifunctional precursor to the initiator is 1:0.001~0.1; The mass ratio of the multifunctional precursor to the plasticizer is 1:1~3; The mass ratio of the multifunctional precursor to the low binding energy solvent is 1:8~14; The mass ratio of the multifunctional precursor to the lithium salt is 1:1 to 5; The preparation method of the fast-charging gel polymer electrolyte includes the following steps: The support membrane is immersed in a plasticizing agent solution, and the solvent is removed to obtain a support membrane loaded with plasticizing agent. A precursor solution is obtained by mixing a multifunctional precursor, a plasticizer, a low binding energy solvent, a lithium salt, and an initiator. The precursor solution is dropped onto the support membrane loaded with the plasticizing agent to obtain a support membrane wetted by the precursor solution and loaded with the plasticizing agent. The precursor solution-wetted support membrane loaded with a plasticizing agent is subjected to in-situ polymerization to obtain the fast-charging gel polymer electrolyte.

2. A lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is the fast-charging gel polymer electrolyte as described in claim 1.

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