Phosphate group-containing polymer solid electrolyte as well as preparation method and application thereof

Abstract

The invention discloses a phosphate group-containing polymer solid electrolyte and a preparation method and application thereof, and belongs to the technical field of solid electrolytes. The raw materials of the polymer solid electrolyte at least comprise an acrylate phosphate functional monomer and an acrylate monomer, the structural general formula of the acrylate phosphate functional monomer is as shown in formula (1): # imgabs0 #, wherein n is an integer selected from 0-8. The polymer solid electrolyte provided by the invention has good interfacial compatibility, and can inhibit the decomposition side reaction of the electrolyte under high pressure, thereby adapting to the requirement of a high-energy-density battery. The battery containing the electrolyte has higher ionic conductivity and flame retardant property.

Description

Technical Field

[0001] The present invention relates to the technical field of solid electrolytes, and particularly relates to a polymer solid electrolyte containing a phosphate group, a preparation method thereof, and an application thereof. Background Art

[0002] Currently, commercially available lithium-ion batteries mainly use carbonate-based liquid electrolytes, which have relatively high ionic conductivity. However, with the development of society and the progress of technology, people have put forward higher requirements for power supply batteries of electronic devices such as electric vehicles, energy storage devices, drones, and medical devices: 1) higher safety; 2) higher energy density; 3) faster charging speed, etc. The liquid electrolyte has characteristics such as flammability, volatility, and poor thermal stability, resulting in great potential safety hazards in current liquid lithium-ion batteries; and the compatibility of the liquid electrolyte with high-energy density cathode materials is insufficient, which limits the further improvement of battery performance. In addition, side reactions of the liquid electrolyte under high-voltage conditions may lead to attenuation of the battery cycle performance, especially the risk is aggravated in high-temperature or high-voltage scenarios, and it is difficult to meet the future market's requirements for high specific energy, high safety, and diverse applications of batteries.

[0003] Solid electrolytes are regarded as the core materials for next-generation battery technologies due to their high safety, wide electrochemical window, and mechanical strength. Existing inorganic solid electrolytes such as sulfides and oxides have high conductivity, but large interfacial impedance and difficult processing. Polymer solid electrolytes have attracted much attention due to their good flexibility and easy processing, but their ionic conductivity is generally low, and traditional PEO-based electrolytes have problems such as high crystallinity and low room-temperature ionic conductivity (1×10 -7 -1×10 -8 S / cm), etc. The introduction of phosphate functional monomers can further significantly improve the ionic conductivity (0.5×10 -4 -2×10 -7 S / cm) and improve the flame retardancy, providing new ideas for the industrialization of all-solid-state batteries. Providing more polymer solid electrolytes containing phosphate functional monomers with excellent comprehensive performance and studying the film-forming properties of the polymer solid electrolytes are the research focuses in this field. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a polymer solid electrolyte containing a phosphate group, a preparation method thereof, and an application thereof to solve the above technical problems.

[0005] The technical solution of the present invention is as follows:

[0006] In the first aspect of the present invention, a polymer solid electrolyte containing a phosphate group is provided, and the raw materials of the polymer solid electrolyte at least include an acrylate phosphate functional monomer and an acrylate monomer;

[0007] The structural general formula of the acrylate phosphate functional monomer is shown in Formula (1):

[0008]

[0009] Among them, the n is selected from integers between 0 and 8.

[0010] Preferably, the acrylate phosphate functional monomer includes at least one of 2-(phosphonyloxy)ethyl 2-methylacrylate and 2-(phosphonyloxy)butyl 2-methylacrylate; and / or,

[0011] In the raw materials of the polymer solid electrolyte containing a phosphate group, the mass fraction of the acrylate phosphate functional monomer is 10-20%.

[0012] Preferably, the acrylate monomer includes at least one of ethyl acrylate, butyl acrylate, isooctyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, butyl methacrylate, and 2-hydroxyethyl methacrylate; and / or,

[0013] In the raw materials of the polymer solid electrolyte containing a phosphate group, the mass fraction of the acrylate monomer is 1-8%.

[0014] Preferably, the mass ratio of the acrylate phosphate functional monomer to the acrylate monomer is 2.5:1 to 10:1.

[0015] Preferably, the polymer solid electrolyte further includes an initiator, an organic solvent, and a lithium salt.

[0016] Preferably, the initiator includes at least one of azobisisobutyronitrile, azobisisoheptonitrile, benzoyl peroxide, and lauroyl peroxide; and / or,

[0017] In the raw materials of the polymer solid electrolyte containing a phosphate group, the mass fraction of the initiator is 0.05-1.5%.

[0018] Preferably, the organic solvent includes at least one of tetrahydrofuran, acetonitrile, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, 1,2-dimethoxyethane, N-methylpyrrolidone, diethylene glycol dimethyl ether, and dimethyl sulfoxide; and / or,

[0019] In the raw materials of the polymer solid electrolyte containing a phosphate group, the mass fraction of the organic solvent is 45-70%.

[0020] Preferably, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium tris(trifluoromethanesulfonate)methyl, and lithium perchlorate; and / or,

[0021] In the raw materials of the polymer solid electrolyte containing a phosphate ester group, the mass fraction of the lithium salt is 20-40%.

[0022] The second aspect of the present invention provides a polymer solid electrolyte membrane, which includes the polymer solid electrolyte described in the first aspect above;

[0023] Preferably, the thickness of the polymer solid electrolyte membrane is 100-800 μm, and / or,

[0024] The room temperature ionic conductivity of the polymer solid electrolyte membrane is 0.5×10 -4 ~2×10 -7 S / cm.

[0025] The third aspect of the present invention provides a preparation method of the polymer solid electrolyte membrane described in the second aspect above, and the preparation method includes the following steps:

[0026] Provide part of the organic solvent;

[0027] After mixing the acrylate phosphate functional monomer and the acrylate monomer, drop them into part of the organic solvent to obtain a first mixed solution;

[0028] After mixing the initiator and the remaining organic solvent, drop them into the first mixed solution. After the dropping is completed, continue the heat preservation reaction to obtain an acrylic polymer;

[0029] After cooling to room temperature, add the lithium salt and mix to obtain a second mixed solution;

[0030] Pour the second mixed solution into a mold and dry it to obtain a polymer solid electrolyte membrane;

[0031] Wherein, part of the organic solvent accounts for 70-90% of the total mass of the organic solvent.

[0032] The fourth aspect of the present invention provides a battery, which includes the polymer solid electrolyte described in the first aspect above, or the polymer solid electrolyte membrane described in the second aspect above, or the polymer solid electrolyte membrane prepared by the preparation method described in the third aspect above.

[0033] The beneficial technical effects of the present invention are as follows:

[0034] The present invention provides a polymer solid electrolyte containing phosphate groups. By introducing an acrylate phosphate functional monomer containing both phosphate groups and acrylate groups, through functional design at the molecular level, the performance limitations of traditional materials are broken through. This substance combines the flame retardancy of phosphate esters, the polymerization ability of acrylates, and the stability of cross-linked structures, which can effectively reduce the combustion risk of the electrolyte and provide a new path for the development of high-performance and highly flame-retardant quasi-solid or all-solid batteries. At the same time, when the above acrylate phosphate functional monomer is mixed with acrylate monomers to prepare a polymer solid electrolyte, the acrylate phosphate functional monomer and acrylate synergistically enhance the antioxidant ability of the polymer, broaden the electrochemical window of the electrolyte. Therefore, the prepared material has good interfacial compatibility and can inhibit the decomposition side reactions of the electrolyte under high voltage, thus meeting the requirements of high-energy-density batteries. At the same time, the introduction of phosphate groups enables the electrolyte to have better interaction with lithium salt anions, promoting the dissociation of lithium ions. Therefore, the battery containing this electrolyte has higher ionic conductivity and mechanical properties. Brief Description of the Drawings

[0035] Figure 1 It is the EIS diagram of the polymer solid electrolyte prepared in Example 1 of the present invention.

[0036] Figure 2 It is the EIS diagram of the polymer solid electrolyte prepared in Example 5 of the present invention.

[0037] Figure 3 It is the comparison diagram of the combustion test between the polymer solid electrolyte prepared in Example 1 of the present invention and PEO.

[0038] Figure 4 It is the LSV test diagram of the polymer solid electrolyte prepared in Example 1 of the present invention. Detailed Embodiments

[0039] The present invention will be specifically described below in conjunction with embodiments.

[0040] Aiming at the problems of existing polymer solid electrolytes, a polymer solid electrolyte containing phosphate groups, its preparation method and application are provided to solve the above technical problems.

[0041] In the first aspect of the present invention, a polymer solid electrolyte containing phosphate groups is provided. The raw materials of the polymer solid electrolyte at least include an acrylate phosphate functional monomer and acrylate monomers;

[0042] The structural general formula of the acrylate phosphate functional monomer is shown in formula (1):

[0043]

[0044] Among them, n is selected from integers between 0 and 8, including but not limited to 0, 1, 2, 3, 4, 5, 6, 7, 8.

[0045] It can be understood that the main chain of the polymer in the polymer solid electrolyte of the present invention is composed of C-C bonds. C-C bonds are non-polar and symmetric, with stronger chemical inertness, usually requiring higher energy for thermal decomposition, and mainly undergoing random chain scission, making it not prone to rapid depolymerization. While the main chain of the traditional ether-based polymer solid electrolyte is composed of polar C-O bonds, which is prone to rapid depolymerization under high temperature and high pressure.

[0046] In some embodiments, the acrylate phosphate functional monomer includes at least one of 2-(phosphonyloxy)ethyl 2-methylacrylate and 2-(phosphonyloxy)butyl 2-methylacrylate.

[0047] In some embodiments, in the raw materials of the polymer solid electrolyte containing a phosphate group, the mass fraction of the acrylate phosphate functional monomer is 10-20%, including but not limited to 10%, 12%, 14%, 16%, 18%, 20%.

[0048] In some embodiments, the acrylate monomer includes at least one of ethyl acrylate, butyl acrylate, isooctyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, butyl methacrylate, and 2-hydroxyethyl methacrylate.

[0049] In some embodiments, in the raw materials of the polymer solid electrolyte containing a phosphate group, the mass fraction of the acrylate monomer is 1-8%, including but not limited to 1%, 2%, 4%, 6%, 8%.

[0050] In some embodiments, the mass ratio of the acrylate phosphate functional monomer to the acrylate monomer is 2.5:1 to 10:1.

[0051] In some embodiments, the polymer solid electrolyte further includes an initiator, an organic solvent, and a lithium salt.

[0052] In some embodiments, the initiator includes at least one of azobisisobutyronitrile, azobisisoheptonitrile, benzoyl peroxide, and lauroyl peroxide.

[0053] In some embodiments, in the raw materials of the polymer solid electrolyte containing a phosphate group, the mass fraction of the initiator is 0.05-1.5%, including but not limited to 0.05%, 0.1%, 0.2%, 0.4%, 0.6%, 0.7%, 1.0%, 1.5%.

[0054] In some embodiments, the organic solvent includes at least one of tetrahydrofuran, acetonitrile, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, 1,2-dimethoxyethane, N-methylpyrrolidone, diethylene glycol dimethyl ether, and dimethyl sulfoxide.

[0055] In some embodiments, in the raw materials of the polymer solid electrolyte containing a phosphate group, the mass fraction of the organic solvent is 45-70%, including but not limited to 45%, 50%, 55%, 60%, 65%, 70%.

[0056] In some embodiments, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium tris(trifluoromethanesulfonate)methyl, and lithium perchlorate.

[0057] In some embodiments, in the raw materials of the polymer solid electrolyte containing a phosphate group, the mass fraction of the lithium salt is 20-40%, including but not limited to 20%, 25%, 30%, 35%, 40%.

[0058] In some embodiments, by mass percentage, the raw materials of the polymer solid electrolyte containing a phosphate group include: 10-20% of acrylate phosphate functional monomer, 1-8% of acrylate monomer, 0.05-1% of initiator, 50-70% of organic solvent, and 20-40% of lithium salt. The second aspect of the present invention provides a polymer solid electrolyte membrane, and the polymer solid electrolyte membrane includes the polymer solid electrolyte described in the above first aspect.

[0059] In some embodiments, the thickness of the electrolyte membrane is 100-800 μm, including but not limited to 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm.

[0060] In some embodiments, the polymer solid electrolyte membrane is all-solid, and its room temperature ionic conductivity is 0.5×10 -4 ~2×10 -7 S / cm.

[0061] The third aspect of the present invention provides a preparation method of the electrolyte membrane described in the above second aspect, and the preparation method includes the following steps:

[0062] S1: Provide part of the organic solvent and heat it;

[0063] S2: After mixing the acrylate phosphate functional monomer and the acrylate monomer, drop them into part of the organic solvent to obtain a first mixed solution;

[0064] S3: After mixing the initiator and the remaining portion of the organic solvent, drop them into the first mixture. After the dropping is completed, continue the heat preservation reaction to obtain an acrylic polymer.

[0065] S4: After cooling to room temperature, add the lithium salt and mix evenly to obtain a second mixture.

[0066] S5: Pour the second mixture into a mold and dry it to obtain a polymer solid electrolyte membrane.

[0067] Among them, a part of the organic solvent accounts for 70-90% of the total mass of the organic solvent.

[0068] In some embodiments, in S1, the providing a part of the organic solvent is specifically to take out a part from the organic solvent and place it in a reaction flask.

[0069] In some embodiments, in S1, the heating is to heat the reaction flask containing a part of the organic solvent to an appropriate temperature and maintain this temperature.

[0070] In some embodiments, the appropriate temperature includes 50-100 °C, including but not limited to 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C.

[0071] In some embodiments, in S2, the preparation method of the first mixture is specifically: after mixing the acrylate phosphate functional monomer and the acrylate monomer evenly, drop them into the reaction flask containing a part of the organic solvent at an appropriate flow rate to obtain the first mixture.

[0072] In some embodiments, in S3, the preparation method of the acrylic polymer includes: after mixing the initiator and the remaining portion of the organic solvent evenly, drop them into the first mixture at an appropriate flow rate. After the dropping is completed, continue to maintain the heating temperature to make the acrylate monomer polymerize in the presence of the initiator to obtain an acrylic polymer.

[0073] In some embodiments, the maintained heating temperature is 50-100 °C, including but not limited to 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, and the time is 2-6 h, including but not limited to 2 h, 3 h, 4 h, 5 h, 6 h.

[0074] In some embodiments, in steps S2 and S3, the appropriate flow rate is 0.5 mL / min - 2 mL / min, including but not limited to 0.5 mL / min, 1.0 mL / min, 1.5 mL / min, 2 mL / min.

[0075] In some embodiments, in S5, the present invention does not limit the mold used. Exemplarily, the mold is a polytetrafluoroethylene mold.

[0076] In some embodiments, in S5, the drying is vacuum high-temperature drying, and the solvent is volatilized by vacuum high-temperature drying.

[0077] In some embodiments, the temperature of the vacuum high-temperature drying is 80-180 °C, including but not limited to 80 °C, 100 °C, 120 °C, 140 °C, 160 °C, 180 °C, and the time until constant weight is reached by volatilization is 12-48 h, including but not limited to 12 h, 20 h, 24 h, 30 h, 36 h, 40 h, 48 h.

[0078] The fourth aspect of the present invention provides a battery, which includes the polymer solid electrolyte described in the first aspect above, or the electrolyte membrane described in the second aspect above, or the electrolyte membrane prepared by the preparation method described in the third aspect above.

[0079] The present invention will be further described below through examples and the like.

[0080] Example 1

[0081] A phosphoric acid ester group-containing acrylic polymer solid electrolyte or polymer solid electrolyte membrane, and its preparation method includes the following steps:

[0082] Step 1: Take a four-necked reaction flask, add 20 g of N-methylpyrrolidone, and heat to 100 °C.

[0083] Step 2: Mix 5.0 g of 2-(phosphonyloxy)ethyl 2-methyl-2-propenoate, 0.3 g of ethyl acrylate, and 0.2 g of methyl methacrylate evenly, and drop them into the reaction flask in Step 1 at a flow rate of 1.5 mL / min; at the same time, mix 0.4 g of azobisisobutyronitrile with 5.0 g of N-methylpyrrolidone evenly, and drop them into the reaction flask in Step 1 at a flow rate of 0.3 mL / min; after the dropping is completed, continue to maintain 100 °C for 3 h to cause the acrylate monomers to undergo a polymerization reaction in the presence of an initiator to obtain a polyacrylate polymer.

[0084] Step 3: After the reaction in Step 2 is completed, add 15 g of lithium bis(fluorosulfonyl)imide salt to the reaction solution after the temperature drops to room temperature, and mix well to obtain a mixed solution.

[0085] Step 4: Pour the mixed solution in Step 3 into a polytetrafluoroethylene mold, and vacuum dry it at 180 °C for 12 h to volatilize N-methylpyrrolidone to obtain a polymer solid electrolyte or polymer solid electrolyte membrane.

[0086] Example 2

[0087] A phosphoric acid ester group-containing acrylic polymer solid electrolyte or polymer solid electrolyte membrane, and its preparation method includes the following steps:

[0088] Step 1: Take a four-necked reaction flask, add 20 g of N-methylpyrrolidone, and heat to 100 °C.

[0089] Step 2: Mix 5 g of 2-(phosphonyloxy)ethyl 2-methyl-2-propenoate, 0.4 g of ethyl acrylate, 0.4 g of butyl acrylate, and 0.2 g of isooctyl acrylate evenly, and drip them into the reaction flask in Step 1 at a flow rate of 1.5 mL / min; meanwhile, mix 0.6 g of azobisisobutyronitrile with 5.0 g of N-methylpyrrolidone evenly, and drip them into the reaction flask in Step 1 at a flow rate of 0.5 mL / min; after the dripping is completed, continue to maintain at 100 °C for 3 h to make the acrylate monomers undergo a polymerization reaction in the presence of an initiator to obtain a polyacrylate polymer.

[0090] Step 3: After the reaction in Step 2 is completed, add 15 g of lithium bis(fluorosulfonyl)imide salt to the reaction solution after the temperature drops to room temperature, and mix evenly to obtain a mixed solution.

[0091] Step 4: Pour the mixed solution in Step 3 into a polytetrafluoroethylene mold, and vacuum dry it at 180 °C for 12 h to volatilize N-methylpyrrolidone to obtain a polymer solid electrolyte or a polymer solid electrolyte membrane.

[0092] Example 3

[0093] A polymer solid electrolyte or a polymer solid electrolyte membrane containing a phosphate ester group, and its preparation method includes the following steps:

[0094] Step 1: Take a four-necked reaction flask, add 20 g of N-methylpyrrolidone, and heat to 100 °C.

[0095] Step 2: Mix 5.0 g of 2-(phosphonyloxy)ethyl 2-methyl-2-propenoate, 0.4 g of butyl acrylate, 0.4 g of methyl methacrylate, 0.1 g of 2-hydroxyethyl acrylate, and 0.1 g of isooctyl acrylate evenly, and drip them into the reaction flask in Step 1 at a flow rate of 1.5 mL / min; meanwhile, mix 0.6 g of azobisisobutyronitrile with 5.0 g of N-methylpyrrolidone evenly, and drip them into the reaction flask in Step 1 at a flow rate of 0.3 mL / min; after the dripping is completed, continue to maintain at 100 °C for 3 h to make the acrylate monomers undergo a polymerization reaction in the presence of an initiator to obtain a polyacrylate polymer.

[0096] Step 3: After the reaction in Step 2 is completed, add 15 g of lithium bis(fluorosulfonyl)imide salt to the reaction solution after the temperature drops to room temperature, and mix evenly to obtain a mixed solution.

[0097] Step 4: Pour the mixture obtained in Step 3 into a polytetrafluoroethylene mold, and vacuum dry it at 180 °C for 24 h. After the N-methylpyrrolidone is volatilized, a polymer solid electrolyte or a polymer solid electrolyte membrane is obtained.

[0098] Example 4

[0099] A polymer solid electrolyte or a polymer solid electrolyte membrane containing a phosphoric acid ester group, and its preparation method includes the following steps:

[0100] Step 1: Take a four-necked reaction flask, add 20 g of N,N-dimethylformamide, and heat it to 100 °C.

[0101] Step 2: Mix 4.0 g of 2-(phosphonyloxy)propyl 2-methyl-2-propenoate, 0.8 g of butyl acrylate, 0.4 g of butyl methacrylate, and 0.3 g of 2-hydroxyethyl acrylate evenly, and drip them into the reaction flask in Step 1 at a flow rate of 1.5 mL / min; at the same time, mix 0.4 g of azobisisobutyronitrile with 5.0 g of N,N-dimethylformamide evenly, and drip them into the reaction flask in Step 1 at a flow rate of 0.3 mL / min; after the dripping is completed, continue to maintain 100 °C for 2 h to cause the acrylate monomers to undergo a polymerization reaction in the presence of an initiator, and a polyacrylate polymer is obtained.

[0102] Step 3: After the reaction in Step 2 is completed, after the temperature of the reaction solution drops to room temperature, add 15 g of lithium trifluoromethanesulfonate, and mix well to obtain a mixed solution.

[0103] Step 4: Pour the mixture obtained in Step 3 into a polytetrafluoroethylene mold, and vacuum dry it at 150 °C for 48 h. After the N,N-dimethylformamide is volatilized, a polymer solid electrolyte or a polymer solid electrolyte membrane is obtained.

[0104] Example 5

[0105] A polymer solid electrolyte or a polymer solid electrolyte membrane containing a phosphoric acid ester group, and its preparation method includes the following steps:

[0106] Step 1: Take a four-necked reaction flask, add 20 g of N,N-dimethylformamide, and heat it to 100 °C.

[0107] Step 2: Mix 4.0 g of 2-(phosphonyloxy)propyl 2-methyl-2-propenoate, 0.8 g of butyl acrylate, 0.4 g of butyl methacrylate, and 0.3 g of 2-hydroxyethyl acrylate uniformly, and drop the mixture into the reaction flask in Step 1 at a flow rate of 1.5 mL / min. Meanwhile, mix 0.6 g of azobisisobutyronitrile with 5.0 g of N,N-dimethylformamide uniformly, and drop the mixture into the reaction flask in Step 1 at a flow rate of 0.3 mL / min. After the dropping is completed, continue to maintain at 120 °C for 4 h to cause the acrylate monomers to undergo a polymerization reaction in the presence of an initiator, obtaining a polyacrylate polymer.

[0108] Step 3: After the reaction in Step 2 is completed, add 15 g of lithium trifluoromethanesulfonate to the reaction solution after the temperature drops to room temperature, and mix well to obtain a mixed solution.

[0109] Step 4: Pour the mixed solution in Step 3 into a polytetrafluoroethylene mold, and vacuum dry at 150 °C for 48 h. After the N,N-dimethylformamide volatilizes, a polymer solid electrolyte or a polymer solid electrolyte membrane is obtained.

[0110] Example 6

[0111] A polymer solid electrolyte or a polymer solid electrolyte membrane containing a phosphate group-containing acrylic polymer, and its preparation method includes the following steps:

[0112] Step 1: Take a four-necked reaction flask, add 20 g of N-methylpyrrolidone, and heat to 100 °C.

[0113] Step 2: Mix 5.0 g of 2-(phosphonyloxy)butyl 2-methyl-2-propenoate, 0.3 g of ethyl acrylate, and 0.2 g of methyl methacrylate uniformly, and drop the mixture into the reaction flask in Step 1 at a flow rate of 1.5 mL / min. Meanwhile, mix 0.4 g of azobisisobutyronitrile with 5.0 g of N-methylpyrrolidone uniformly, and drop the mixture into the reaction flask in Step 1 at a flow rate of 0.3 mL / min. After the dropping is completed, continue to maintain at 100 °C for 2 h to cause the acrylate monomers to undergo a polymerization reaction in the presence of an initiator, obtaining a polyacrylate polymer.

[0114] Step 3: After the reaction in Step 2 is completed, add 15 g of lithium bis(fluorosulfonyl)imide to the reaction solution after the temperature drops to room temperature, and mix well to obtain a mixed solution.

[0115] Step 4: Pour the mixed solution in Step 3 into a polytetrafluoroethylene mold, and vacuum dry at 180 °C for 12 h. After the N-methylpyrrolidone volatilizes, a polymer solid electrolyte or a polymer solid electrolyte membrane is obtained.

[0116] Comparative Example 1

[0117] A solid electrolyte of an acrylic polymer or a polymer solid electrolyte membrane containing a phosphate group, and its preparation method includes the following steps:

[0118] Step 1: Take a four-necked reaction flask, add 20 g of N-methylpyrrolidone, and heat to 100 °C.

[0119] Step 2: Mix 5.0 g of n-butyl acrylate, 0.3 g of ethyl acrylate, and 0.2 g of methyl methacrylate evenly, and drip them into the reaction flask in Step 1 at a flow rate of 1.5 mL / min; meanwhile, mix 0.4 g of azobisisobutyronitrile with 5.0 g of N-methylpyrrolidone evenly, and drip them into the reaction flask in Step 1 at a flow rate of 0.3 mL / min; after the dripping is completed, continue to maintain 100 °C for 3 h to make the acrylate monomers undergo a polymerization reaction in the presence of an initiator to obtain a polyacrylate polymer.

[0120] Step 3: After the reaction in Step 2 is completed, add 15 g of lithium bis(fluorosulfonyl)imide salt to the reaction solution after the temperature drops to room temperature, and mix well to obtain a mixed solution.

[0121] Step 4: Pour the mixed solution in Step 3 into a polytetrafluoroethylene mold, and vacuum dry it at 180 °C for 12 h. After the N-methylpyrrolidone evaporates, a polymer solid electrolyte is obtained.

[0122] The polymer solid electrolyte membrane obtained by pouring and drying the obtained mixed solution is more brittle than that of the example. When assembling the battery with two pieces of stainless steel clamped, the membrane layer is fragile.

[0123] Comparative Example 2

[0124] A solid electrolyte of an acrylic polymer or a polymer solid electrolyte membrane containing a phosphate group, and its preparation method is basically the same as that of Example 1, except for Step 2. Step 2 is as follows:

[0125] Step 2: Drop 5.5 g of 2-(phosphonyloxy)ethyl 2-methylacrylate into the reaction flask in Step 1 at a flow rate of 1.5 mL / min; meanwhile, mix 0.4 g of azobisisobutyronitrile with 5.0 g of N-methylpyrrolidone evenly, and drip them into the reaction flask in Step 1 at a flow rate of 0.3 mL / min; after the dripping is completed, continue to maintain 100 °C for 3 h to make the acrylate monomers undergo a polymerization reaction in the presence of an initiator to obtain a polyacrylate polymer.

[0126] When the polymer solid electrolyte membrane obtained in this comparative example is assembled into a battery with two pieces of stainless steel clamped, the membrane layer is also easily broken.

[0127] Comparative Example 3

[0128] A solid-state electrolyte or polymer solid electrolyte membrane of an acrylic polymer containing a phosphate group, the preparation method of which is basically the same as that of Example 1, except that the amounts of substances in Step 2 are changed. Step 2 is as follows:

[0129] Step 2: Mix 2.75 g of 2-(phosphonyloxy)ethyl 2-methyl-2-propenoate, 1.65 g of ethyl acrylate, and 1.1 g of methyl methacrylate evenly, and drop them into the reaction flask of Step 1 at a flow rate of 1.5 mL / min; at the same time, mix 0.4 g of azobisisobutyronitrile and 5.0 g of N-methylpyrrolidone evenly, and drop them into the reaction flask of Step 1 at a flow rate of 0.3 mL / min; after the dropping is completed, continue to maintain at 100 °C for 3 h to cause the acrylate monomers to undergo a polymerization reaction in the presence of an initiator to obtain a polyacrylate polymer.

[0130] Test Example:

[0131] (1) Measurement of the thickness of the electrolyte membrane:

[0132] Use a micrometer (accuracy 0.01 mm) to measure the thickness of the polymer solid electrolyte of the example and the comparative example, and randomly take 3 points on the membrane for measurement and calculate the average value. The results are shown in Table 1.

[0133] (2) Flame retardancy of the electrolyte membrane

[0134] Place the electrolyte membrane of Example 1 on a glass plate and burn it horizontally with an open flame, and record the pictures at different combustion times respectively. The results are as Figure 3 shown. Among them, Figure a shows the combustion situation of a common PEO membrane. Figure b shows the combustion diagrams of the polymer solid electrolyte membrane of the example of the present invention at different times. It can be seen from the figure that compared with the PEO membrane, the electrolyte membrane prepared in Example 1 of the present invention has better combustion resistance.

[0135] (3) Measurement of the room temperature ionic conductivity of the battery:

[0136] Assemble the polymer solid electrolytes prepared in the examples and the comparative examples into batteries respectively. The specific method is as follows: clamp the electrolyte with two pieces of stainless steel and place it in a 2032-type battery case. The lithium ion conductivity is measured by electrochemical impedance spectroscopy to measure its impedance, and calculated according to the formula where L is the thickness of the polymer solid electrolyte, S is the area of the stainless steel gasket, and R is the measured impedance value. The results are shown in Table 1.

[0137] Table 1 Performance tests of examples and comparative examples

[0138]

[0139] It can be seen from Table 1 that the battery corresponding to the electrolyte prepared in the embodiment of the present invention has a higher conductivity.

[0140] Figure 1-2 They are the EIS graphs of the polymer solid electrolytes prepared in Example 1 and Example 5, respectively. It can be seen from the graphs that the impedance of Example 1 is 280Ω, and the impedance of Example 5 is 800Ω.

[0141] Figure 4 This is the LSV test result of the polymer solid electrolyte prepared in Example 1. As can be seen from the figure, its electrochemical window is 4.25V.

[0142] The present invention introduces phosphate groups into polymer solid electrolytes, which are obtained by polymerizing acrylate phosphate functional monomers, other acrylate monomers, initiators and solvents, and then drying and doping lithium salts to form films. The unique phosphate groups have good lithium ion binding and release capabilities, and promote the transmission of lithium ions. The polymer solid electrolyte has good film-forming performance, excellent electrochemical stability, good thermal stability, high room temperature ionic conductivity, and low interface resistance, and can be applied to solid-state lithium-ion batteries, providing a new direction for the development of solid electrolytes.

[0143] The above is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. A polymer solid electrolyte containing phosphate groups, characterized in that: The raw materials of the polymer solid electrolyte at least include acrylate phosphate functional monomers and acrylate monomers; The general structural formula of the acrylic ester phosphate functional monomer is shown in formula (1): Wherein, the n is selected from an integer between 0 and 8.

2. The polymer solid electrolyte according to claim 1, characterized in that The acrylate phosphate functional monomer includes at least one of 2-methyl-2-acrylate-2-(phosphonooxy)ethyl ester and 2-methyl-2-acrylate-2-(phosphonooxy)butyl ester; and / or, In the raw materials of the polymer electrolyte containing phosphate groups, the mass fraction of the acrylate phosphate functional monomer is 10-20%.

3. The polymer solid electrolyte according to any one of claims 1 to 2, characterized in that: The acrylic acid ester monomer includes at least one of ethyl acrylate, butyl acrylate, isooctyl acrylate, hydroxyethyl acrylate, methyl methacrylate, butyl methacrylate and hydroxyethyl methacrylate; and / or, In the raw material of the polymer solid electrolyte containing phosphate groups, the mass fraction of the acrylate monomer is 1 to 8%; Preferably, the mass ratio of the acrylate phosphate functional monomer to the acrylate monomer is 2.5:1 to 10:

1.

4. The polymer solid electrolyte according to claim 3, characterized in that: The polymer solid electrolyte further comprises an initiator, an organic solvent and a lithium salt.

5. The polymer solid electrolyte according to claim 4, characterized in that: The initiator comprises at least one of azobisisobutyronitrile, azobisisoheptylnitrile, dibenzoyl peroxide and dodecanoyl peroxide; and / or, In the raw material of the polymer solid electrolyte containing phosphate groups, the mass fraction of the initiator is 0.05-1.5%.

6. The polymer solid electrolyte according to claim 4, characterized in that: The organic solvent includes at least one of tetrahydrofuran, acetonitrile, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, 1,2-dimethoxyethane, N-methylpyrrolidone, diethylene glycol dimethyl ether, and dimethyl sulfoxide; and / or, In the raw material of the polymer solid electrolyte containing phosphate groups, the mass fraction of the organic solvent is 45-70%.

7. The polymer solid electrolyte according to claim 4, characterized in that: The lithium salt comprises at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, methyl lithium tris(trifluoromethanesulfonate), and lithium perchlorate; and / or, In the raw material of the polymer solid electrolyte containing phosphate groups, the mass fraction of the lithium salt is 20-40%.

8. A polymer solid electrolyte membrane, characterized in that: The polymer solid electrolyte membrane comprises the polymer solid electrolyte according to any one of claims 1 to 7; Preferably, the thickness of the electrolyte membrane is 100 to 800 μm, and / or, The room temperature ionic conductivity of the electrolyte membrane is 0.5×10 -4 ~2×10 -7 S / cm.

9. A method for preparing the polymer solid electrolyte membrane according to claim 8, characterized in that: The preparation method comprises the following steps: providing a portion of the organic solvent; The acrylate phosphate functional monomer and the acrylate monomer are mixed, and then added dropwise to a portion of the organic solvent to obtain a first mixed solution; The initiator and the remaining organic solvent are mixed and then dripped into the first mixed solution. After the dripping is completed, the mixture is kept warm for reaction to obtain an acrylic acid polymer; After cooling to room temperature, adding the lithium salt and mixing to obtain a second mixed solution; pouring the second mixed liquid into a mold and drying it to obtain a polymer solid electrolyte membrane; Wherein, part of the organic solvent accounts for 70-90% of the total mass of the organic solvent.

10. A battery, characterized in that: The battery comprises the polymer solid electrolyte according to any one of claims 1 to 7, or the polymer solid electrolyte membrane according to claim 8, or the polymer solid electrolyte membrane prepared by the preparation method according to claim 9.

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