A polymer, a polymer electrolyte, a solid-state battery, and an electrical device.

Abstract

This invention provides a polymer, a polymer electrolyte, a solid-state battery, and an electrical device. The polymer provided is copolymerized from monomer A and crosslinking agent B. Monomer A contains ethoxy groups and ester groups. The introduction of ester groups reduces the crystallinity of ethoxy groups, allowing more ethoxy groups to participate in lithium-ion transport and improving the ionic conductivity of the electrolyte. Simultaneously, the binding force between ester groups and lithium ions is weaker than that between oxygen atoms and lithium ions, providing more favorable sites for lithium-ion transport, thus resulting in higher ionic conductivity and lithium-ion transference number. The addition of the crosslinking agent improves the mechanical strength of the electrolyte. Therefore, when using the polymer provided by this invention to manufacture a solid-state electrolyte, it can effectively improve the problems of low ionic conductivity and low lithium-ion transference number in existing PEO-based solid-state electrolytes, leading to poor battery cycle performance.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and in particular to a polymer, a polymer electrolyte, a solid-state battery, and an electrical device. Background Technology

[0002] Currently, lithium-ion batteries are widely used due to their advantages such as high energy density and operating voltage, long cycle life and low self-discharge rate.

[0003] In existing technologies, the electrolyte in lithium-ion batteries is generally an organic liquid electrolyte, which has a low flash point, is flammable, and is prone to leakage, thus posing significant safety hazards.

[0004] To address the aforementioned issues, existing solid polymer electrolytes based on polyethylene oxide (PEO) have overcome safety concerns and offer advantages such as light weight, thinness, and ease of processing. They can also be used with lithium metal as the negative electrode to improve the battery's energy density.

[0005] However, existing PEO-based solid electrolytes suffer from problems such as low ionic conductivity and low lithium-ion transference number, resulting in poor cycle performance. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a polymer, a polymer electrolyte, a solid-state battery and an electrical device to solve the problem that the existing PEO-based solid electrolyte has low ionic conductivity and low lithium-ion transference number, resulting in poor battery cycle performance.

[0007] To solve the above problems, the present invention is achieved through the following technical solution:

[0008] The present invention proposes a polymer, wherein the polymer is copolymerized from monomer A and crosslinking agent B, wherein monomer A contains ethoxy groups and ester groups.

[0009] Furthermore, in the polymer, monomer A contains vinyl groups, and crosslinking agent B contains divinyl groups.

[0010] Furthermore, in the polymer, monomer A comprises a compound having formula (I):

[0011]

[0012] R1 is selected from one of hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, and cyano;

[0013] R2 is selected from Any one of the following; a is an integer between 0 and 10; b, c, and d are each independent integers between 1 and 20;

[0014] R3 is selected from hydrogen and C1-C6 alkyl groups;

[0015] m is an integer between 1 and 20; n is an integer between 1 and 50.

[0016] Furthermore, in the polymer, the crosslinking agent B comprises a compound having formula (II):

[0017]

[0018] R4 is selected from one of hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, and cyano groups;

[0019] R5 and R7 are each independently one of -O-, -S-, and -NH-;

[0020] R6 is selected from any one of them; e, f, g, h are each an independent integer between 1 and 20.

[0021] Furthermore, in the polymer, the molar ratio of monomer A to crosslinking agent B is (70-95):(5-30).

[0022] The present invention also proposes a polymer electrolyte comprising a lithium salt and a polymer as described above.

[0023] Furthermore, in the polymer electrolyte, the total molar number of ethoxy units in monomer A and crosslinking agent B, and the molar ratio of the lithium salt, is (25-10):1.

[0024] Furthermore, in the polymer electrolyte, the lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium dioxalate borate.

[0025] The present invention also proposes a solid-state battery, comprising a positive electrode, a negative electrode, and a polymer electrolyte membrane, wherein the polymer electrolyte membrane comprises the polymer electrolyte as described above.

[0026] The present invention also proposes an electrical device, wherein the aforementioned solid-state battery is used as the power supply for the electrical device.

[0027] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0028] In this embodiment of the invention, the provided polymer is copolymerized from monomer A and crosslinking agent B. Monomer A contains ethoxy groups and ester groups. The introduction of ester groups can reduce the crystallinity of ethoxy groups, allowing more ethoxy groups to participate in lithium-ion transport and improving the ionic conductivity of the electrolyte. At the same time, the binding force between ester groups and lithium ions is weaker than that between oxygen atoms and lithium ions, providing more favorable sites for lithium-ion transport, thus resulting in higher ionic conductivity and lithium-ion transference number. The addition of the crosslinking agent can improve the mechanical strength of the electrolyte. Therefore, when using the polymer provided by this invention to make a solid electrolyte, it can effectively improve the problems of low ionic conductivity and low lithium-ion transference number of existing PEO-based solid electrolytes, which lead to poor battery cycle performance.

[0029] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to specific embodiments.

[0031] In existing lithium-ion batteries, the PEO-based solid electrolyte used has low ionic conductivity, low lithium-ion transference number, and poor mechanical strength, resulting in poor rate performance and cycle performance.

[0032] To address the aforementioned problems, this invention provides a polymer, wherein it is copolymerized from monomer A and crosslinking agent B, and monomer A contains ethoxy and ester groups.

[0033] The introduction of ester groups can reduce the crystallinity of ethoxy groups, allowing more ethoxy groups to participate in lithium-ion transport and improving the ionic conductivity of the electrolyte. Simultaneously, the binding force between ester groups and lithium ions is weaker than that between oxygen atoms and lithium ions, providing more favorable sites for lithium-ion transport. This results in higher ionic conductivity and lithium-ion transference number, leading to better rate performance and cycle performance in solid-state batteries. Furthermore, the introduction of ester groups can improve the high-voltage stability of the electrolyte. The addition of crosslinking agents can enhance the mechanical strength of the electrolyte, enabling the fabrication of lithium metal solid-state batteries with high areal density cathodes, resulting in higher energy density and safety performance.

[0034] Therefore, when using the polymer provided by this invention to make a solid electrolyte, it can effectively improve the problems of low ionic conductivity and low lithium-ion transference number of existing PEO-based solid electrolytes, which lead to poor battery cycle performance.

[0035] Optionally, in one embodiment, monomer A contains vinyl groups, and crosslinking agent B contains divinyl groups. The divinyl groups can be rationally crosslinked and polymerized with the vinyl groups in monomer A, effectively improving the mechanical strength of the electrolyte without affecting the ionic conductivity.

[0036] Optionally, in one embodiment, monomer A comprises a compound having formula (I):

[0037]

[0038] R1 is selected from one of hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, and cyano;

[0039] R2 is selected from Any one of the following; a is an integer between 0 and 10; b, c, and d are each independent integers between 1 and 20;

[0040] R3 is selected from hydrogen and C1-C6 alkyl groups;

[0041] m is an integer between 1 and 20; n is an integer between 1 and 50.

[0042] Among them, R2 is selected from When a is 0, the two ester groups at both ends of R2 are directly connected to form oxalate.

[0043] In the above structural formula (Ⅰ), the ester group exists between the ethoxy groups, which can effectively reduce the crystallinity of the ethoxy groups, and the ester group is less affected by the terminal alkenyl group, which can ensure its effective binding with lithium ions.

[0044] Optionally, in one specific embodiment, the crosslinking agent B comprises a compound having formula (II):

[0045]

[0046] R4 is selected from one of hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, and cyano groups;

[0047] R5 and R7 are each independently one of -O-, -S-, and -NH-;

[0048] R6 is selected from any one of them; e, f, g, h are each an independent integer between 1 and 20.

[0049] In the above structural formula (II), the distance between the two vinyl groups is moderate and the steric hindrance is small. This not only makes it suitable for the rational crosslinking and polymerization of the ethoxy and ester groups in monomer A, but also effectively balances the ionic conductivity and mechanical strength of the polymer.

[0050] Optionally, in a more specific embodiment, the molar ratio of monomer A to crosslinking agent B in the polymer is (70-95):(5-30), which can effectively improve the mechanical strength of the polymer electrolyte without restricting the movement of polymer chain segments, ensuring that it has good ionic conductivity and contact performance with positive and negative electrodes.

[0051] The present invention also proposes a polymer electrolyte comprising a lithium salt and a polymer as described above.

[0052] The polymer electrolyte provided by this invention includes the polymer described above. The polymer is copolymerized from monomer A and crosslinking agent B. Monomer A contains ethoxy and ester groups. The combination of ethoxy and ester groups reduces the crystallinity of ethoxy groups, while ester groups can provide additional lithium-ion transport sites. The crosslinking agent can improve the mechanical strength of the electrolyte. The combined action of ethoxy, ester groups and crosslinking agent gives the polymer electrolyte higher ionic conductivity, lithium-ion transference number and mechanical strength.

[0053] Optionally, in one embodiment, in the polymer electrolyte, the total molar number of ethoxy units in monomer A and crosslinking agent B is in a molar ratio of (25-10):1 to the lithium salt, so that the ethoxy units can be reasonably coordinated with lithium ions, which not only facilitates the binding and unbinding of lithium ions, but also effectively improves the ionic conductivity.

[0054] Optionally, in one embodiment, the lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium dioxalate borate, which can effectively match the polymer, thereby giving the electrolyte higher ionic conductivity and lithium-ion transference number, and improving the rate performance and cycle performance of the solid-state battery.

[0055] This invention provides a method for preparing a polymer electrolyte, which includes: mixing monomer A, crosslinking agent B and lithium salt uniformly, adding an initiator to initiate polymerization, and obtaining a polymer electrolyte.

[0056] The initiator mentioned above is any one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl peroxide, benzophenone, methyl benzoate, benzoyl methyl ether, and benzoyl ethyl ether, which can effectively initiate the polymerization and crosslinking of monomer A and crosslinking agent B.

[0057] The present invention also proposes a solid-state battery, comprising a positive electrode, a negative electrode, and a polymer electrolyte membrane, wherein the polymer electrolyte membrane comprises the polymer electrolyte described above.

[0058] Among them, the polymer electrolyte not only plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet, but also can effectively isolate the positive electrode sheet and the negative electrode sheet to prevent short circuit.

[0059] The above-mentioned positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on the above-mentioned positive electrode current collector. The above-mentioned positive electrode active material layer includes a positive electrode active material. The above-mentioned positive electrode active material includes lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium iron phosphate (LiFePO4), lithium cobalt phosphate (LiCoPO4), lithium manganese phosphate (LiMnPO4), lithium nickel phosphate (LiNiPO4), lithium manganate (LiMnO2), binary material LiNi x A (1-x) O2 (where A is selected from one of Co and Mn, 0 < x < 1), ternary material LiNimBnC (1-m-n) O2 (where B and C are independently selected from at least one of Co, Al, and Mn, and B and C are different, 0 < m < 1, 0 < n < 1) and the like.

[0060] Furthermore, the above-mentioned positive electrode sheet further includes a lithium salt, and the lithium salt is selected from one or more of lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium tetrafluoroborate, lithium difluoro(oxalato)borate, and lithium bis(oxalato)borate.

[0061] Furthermore, the lithium salt in the above-mentioned positive electrode sheet is the same as the lithium salt in the polymer electrolyte, ensuring the matching effect between the positive electrode sheet and the electrolyte and improving the conductivity.

[0062] Optionally, in one embodiment, the above-mentioned positive electrode sheet further includes a conductive agent, a binder, and a plasticizer. The above-mentioned conductive agent is selected from at least one of acetylene black, Super P, Super S, graphene, carbon fiber, carbon nanotube, and Ketjen black. The above-mentioned binder is selected from at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polypropylene carbonate, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyethylene oxide, and ethylene oxide-propylene oxide copolymer. The above-mentioned plasticizer is selected from at least one of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, tetrapropylene glycol dimethyl ether, dipropylene glycol diethyl ether, tripropylene glycol diethyl ether, tetrapropylene glycol diethyl ether, 1,3-dioxolane, 1,4-dioxane, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, succinonitrile, and adiponitrile.

[0063] Optionally, in one embodiment, the mass ratio of positive electrode active material, conductive agent, binder, lithium salt and plasticizer in the above positive electrode sheet is (50-90):(1-10):(9-20):(0-10):(0-10), which can effectively balance the energy density and ionic conductivity of the battery.

[0064] In some embodiments, the positive electrode sheet is prepared as follows: the components used to prepare the positive electrode sheet, such as the positive active material, binder and any other components, are dispersed in a solvent such as N-methylpyrrolidone to form a positive electrode slurry; the positive electrode slurry is coated on both sides of a positive electrode current collector such as an aluminum foil; after baking, rolling, cutting and other processes, the positive electrode sheet can be obtained.

[0065] The negative electrode sheet includes a negative current collector and a negative active material layer disposed on the negative current collector. The negative active material layer can be a negative active material used in batteries, such as a metal negative electrode material or a non-metal negative electrode material. The metal negative electrode material is preferably lithium metal or a lithium metal alloy. The non-metal negative electrode material is preferably any one or a combination of at least two of hard carbon, soft carbon, graphite, silicon suboxide, silicon-carbon composite, and silicon alloy.

[0066] Furthermore, when the above-mentioned negative electrode active material is selected from non-metallic negative electrode materials, the above-mentioned negative electrode sheet also includes a lithium salt, wherein the lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium dioxalate borate.

[0067] Furthermore, the lithium salt in the aforementioned negative electrode is the same as the lithium salt in the polymer electrolyte, ensuring the matching effect between the negative electrode and the electrolyte and improving conductivity.

[0068] Optionally, in one embodiment, when the negative electrode active material is selected from non-metallic negative electrode materials, the negative electrode sheet further includes a conductive agent, a binder, and a plasticizer. The conductive agent is selected from at least one of acetylene black, Super P, Super S, graphene, carbon fiber, carbon nanotubes, and Ketjen black. The binder is selected from at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polypropylene carbonate, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyethylene oxide, and ethylene oxide-propylene oxide copolymer. The plasticizer is selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, and diethyl ethylene glycol diethyl ether. At least one of the following: dimethyl glycol ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, tetrapropylene glycol dimethyl ether, dipropylene glycol diethyl ether, tripropylene glycol diethyl ether, tetrapropylene glycol diethyl ether, 1,3-dioxolane, 1,4-dioxane, propylene carbonate, ethylene carbonate, diethyl carbonate or dimethyl carbonate, succinate, and adiponitrile.

[0069] Optionally, in one embodiment, the mass ratio of negative electrode active material, conductive agent, binder, lithium salt and plasticizer in the above-mentioned negative electrode sheet is (50-90):(1-10):(9-20):(0-10):(0-10), which can effectively balance the energy density and ionic conductivity of the battery.

[0070] In some embodiments, the negative electrode sheet is prepared as follows: the components used to prepare the negative electrode sheet, such as the negative electrode active material, binder and conductive agent, are dispersed in a solvent such as deionized water to form a negative electrode slurry; the negative electrode slurry is coated on both sides of a negative electrode current collector such as copper foil; after baking, rolling, cutting and other processes, the negative electrode sheet can be obtained.

[0071] In practical applications, the negative electrode sheet, polymer electrolyte membrane and positive electrode sheet are stacked in sequence and wound to obtain the core, then sealed and sorted to obtain the solid-state battery mentioned above.

[0072] The present invention also proposes an electrical device, wherein the solid-state battery described above is included, and the solid-state battery serves as the power supply for the electrical device.

[0073] The above-described solid-state battery embodiments and electrical device embodiments include the aforementioned polymer electrolyte and achieve the same technical effects. To avoid repetition, they will not be described again here. For relevant details, please refer to the description of the polymer electrolyte embodiments.

[0074] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described below with reference to embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0075] The present invention will be described in detail below through embodiments.

[0076] Example 1

[0077] (1) Preparation of polymer electrolyte membrane:

[0078] Monomer A and crosslinking agent B were mixed evenly at a molar ratio of 90:10. Then, lithium salt was added at a molar ratio of 15:1 to the total molar amount of ethoxy groups on monomer A and crosslinking agent B and lithium salt. Initiator was added at 0.5% of the total mass of monomer A and crosslinking agent B. The mixture was heated to 60°C and polymerized for 4 hours to obtain a polymer electrolyte membrane with a thickness of 40 μm.

[0079] The structural formula of monomer A is as follows: The structural formula of crosslinking agent B is: The lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and the initiator is azobisisobutyronitrile (AIBN).

[0080] (2) Solid-state battery fabrication

[0081] Lithium iron phosphate (LiFePO4), a conductive agent (Super P), a binder (ethylene oxide with a molecular weight of 600,000), a lithium salt (lithium bis(trifluoromethanesulfonyl)imide), and a plasticizer (succinic anionyl) were mixed uniformly in N,N-dimethylformamide at a mass ratio of 78:2:10:5:5. The slurry was then coated onto an aluminum current collector using a scraper. After drying at 60°C for 1 hour, the mixture was further dried at 80°C for 3 hours to obtain the positive electrode sheet. The single-sided areal loading of lithium iron phosphate was 15 mg / cm³. 2 ;

[0082] Cut the positive electrode sheet into 4.5×6cm pieces. 2 A 15μm thick lithium-copper alloy strip was used as the negative electrode and cut into 4.7×6.2cm pieces. 2 The polymer electrolyte membrane was cut to a size of 4.8 × 6.3 cm. 2 Solid-state batteries are assembled in a glove box filled with argon gas, following the order of positive electrode, polymer electrolyte membrane, and negative electrode.

[0083] Example 2

[0084] The only difference from Example 1 is that, in the preparation of the polymer electrolyte membrane, the molar ratio of monomer A and crosslinking agent B is adjusted to 95:5.

[0085] Example 3

[0086] The only difference from Example 1 is that, in the preparation of the polymer electrolyte membrane, the molar ratio of monomer A and crosslinking agent B is adjusted to 80:20.

[0087] Example 4

[0088] The only difference from Example 1 is that, in the preparation of the polymer electrolyte membrane, the molar ratio of monomer A and crosslinking agent B is adjusted to 70:30.

[0089] Example 5

[0090] The only difference from Example 1 is that, in the preparation of the polymer electrolyte membrane, the molar ratio of monomer A and crosslinking agent B is adjusted to 60:40.

[0091] Example 6

[0092] The only difference from Example 1 is that, during the preparation of the polymer electrolyte membrane, the structural formula of monomer A is adjusted to be...

[0093] Example 7

[0094] The only difference from Example 1 is that, during the preparation of the polymer electrolyte membrane, the structural formula of monomer A is adjusted to be...

[0095] Example 8

[0096] The only difference from Example 1 is that, during the preparation of the polymer electrolyte membrane, the structural formula of monomer A is adjusted to be...

[0097] Example 9

[0098] The only difference from Example 1 is that, during the preparation of the polymer electrolyte membrane, the structural formula of monomer A is adjusted to be...

[0099] Example 10

[0100] The difference between Example 10 and Example 1 is that, in the preparation process of the polymer electrolyte membrane, the structural formula of monomer A is adjusted to be...

[0101] Example 11

[0102] The only difference from Example 1 is that, in the preparation process of the polymer electrolyte membrane, the structural formula of the crosslinking agent B is adjusted to be...

[0103] Example 12

[0104] The only difference from Example 1 is that, in the preparation process of the polymer electrolyte membrane, the structural formula of the crosslinking agent B is adjusted to be...

[0105] Example 13

[0106] The only difference from Example 1 is that, in the preparation of the polymer electrolyte membrane, the total molar amount of ethoxy groups on monomer A and crosslinking agent B is adjusted to a molar ratio of lithium salt to 25:1.

[0107] Example 14

[0108] The only difference from Example 1 is that, in the preparation of the polymer electrolyte membrane, the total molar amount of ethoxy groups on monomer A and crosslinking agent B is adjusted to a molar ratio of lithium salt to 10:1.

[0109] Example 15

[0110] The only difference from Example 1 is that the thickness of the polymer electrolyte membrane is adjusted to 20 μm.

[0111] Example 16

[0112] The only difference from Example 1 is that the thickness of the polymer electrolyte membrane is adjusted to 50 μm.

[0113] Example 17

[0114] The only difference from Example 1 is that the lithium salt is changed to lithium tetrafluoroborate.

[0115] Comparative Example 1

[0116] The difference between Comparative Example 1 and Example 1 is that, in the preparation process of the polymer electrolyte membrane, the molar ratio of monomer A and crosslinking agent B was adjusted to 100:0.

[0117] Comparative Example 2

[0118] The difference between Comparative Example 2 and Example 1 is that, in the preparation process of the polymer electrolyte membrane, the polymer electrolyte is adjusted to consist of 600,000 units of polyethylene oxide and lithium bis(trifluoromethanesulfonyl)imide.

[0119] Test example:

[0120] 1) The polymer electrolyte membranes prepared in the above embodiments and comparative examples were assembled with stainless steel sheets to form stainless steel symmetrical cells for ionic conductivity testing. The testing method was as follows: the symmetrical cell was placed in an oven at 60°C for 10 minutes, and then the EIS of the symmetrical cell was measured according to the formula. The ionic conductivity of the polymer electrolyte was calculated; where σ is the ionic conductivity of the electrolyte, L is the thickness of the electrolyte, S is the area of ​​the stainless steel, and R is the impedance of the symmetrical cell; the test results are shown in Table 1.

[0121] The preparation steps of the stainless steel symmetric cell are as follows:

[0122] Stainless steel sheets with a diameter of 16 mm and a thickness of 200 μm and polymer electrolyte membranes with a diameter of 19 mm were cut using a punching machine.

[0123] The obtained stainless steel sheets and polymer electrolyte membranes are stacked in sequence, with the polymer electrolyte membrane positioned between the stainless steel sheets, thus completing the preparation of the stainless steel symmetric battery.

[0124] 2) The polymer electrolyte membranes prepared in the above embodiments and comparative examples were assembled with lithium sheets to form lithium symmetric batteries for lithium-ion transference number testing. The testing method was as follows: the symmetric battery was placed in a 60°C oven for 10 minutes, and then a polarization voltage was applied to the battery using an electrochemical workstation. The current and impedance of the symmetric battery before and after polarization were measured according to the formula. The lithium-ion transference number of the electrolyte can be calculated; where t + For lithium-ion transference numbers, I0 and I ss These are the currents before polarization begins and after polarization stabilizes, R0 and R... ss The values ​​are the impedance before polarization begins and the impedance after polarization stabilizes, respectively. ΔV is the polarization voltage. The polarization voltage is usually 10mV, and the polarization time is usually 2h. The test results are shown in Table 1.

[0125] The preparation steps of a lithium symmetric battery are as follows:

[0126] Lithium sheets with a diameter of 16 mm and a thickness of 200 μm and polymer electrolyte membranes with a diameter of 19 mm were cut using a punching machine.

[0127] The obtained lithium sheets and polymer electrolyte membranes are stacked in sequence, with the polymer electrolyte membrane positioned between the lithium sheets, thus completing the preparation of the lithium symmetric battery.

[0128] 2) The solid-state batteries prepared in each embodiment and comparative example were subjected to battery cycle performance tests, and the test data are shown in Table 1; wherein, the test method is as follows:

[0129] After placing the battery in a 60℃ oven for 10 minutes, charge it at a constant current rate of 0.05C to 3.8V, then let it rest for 5 minutes. Next, discharge it at a constant current rate of 0.05C to 2.5V. Repeat this process three times. Then charge it at a constant current rate of 0.2C to 3.8V, and then charge it at a constant voltage of 3.8V until 0.01C is cut off. Let it rest for 5 minutes, and finally discharge it at a rate of 0.2C to 2.5V, and let it rest for 5 minutes. The battery is considered to have failed when its specific capacity reaches 80% of its initial capacity. Record the number of cycles at this point.

[0130] Table 1

[0131]

[0132]

[0133] Based on the above test data, introducing ethoxy and ester groups into the polymer electrolyte, and adding a crosslinking agent, the polymer electrolyte exhibits higher ionic conductivity, lithium-ion transference number, and mechanical strength under the combined action of ethoxy, ester groups, and crosslinking agent, and can also improve the cycle performance of solid-state batteries.

[0134] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0135] The present invention has provided a detailed description of a polymer, polymer electrolyte, solid-state battery, and electrical device. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A polymer, characterized in that, The polymer is copolymerized from monomer A and crosslinking agent B, wherein monomer A contains ethoxy and ester groups; The monomer A comprises a compound having formula (Ⅰ): R1 is selected from one of hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, and cyano; R2 is selected from Any one of the following; a is an integer between 0 and 10; b, c, and d are each independent integers between 1 and 20; R3 is selected from hydrogen and C1-C6 alkyl groups; m is an integer between 1 and 20; n is an integer between 1 and 50.

2. The polymer according to claim 1, characterized in that, The monomer A contains vinyl groups, and the crosslinking agent B contains divinyl groups.

3. The polymer according to claim 1 or 2, characterized in that, The crosslinking agent B comprises a compound having formula (II): R4 is selected from one of hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, and cyano groups; R5 and R7 are each independently one of -O-, -S-, and -NH-; R6 is selected from any one of them; e, f, g, h are each an independent integer between 1 and 20.

4. The polymer according to claim 2, characterized in that, In the polymer, the molar ratio of monomer A to crosslinking agent B is (70-95):(5-30).

5. A polymer electrolyte, characterized in that, Includes lithium salts and polymers as described in any one of claims 1 to 4.

6. The polymer electrolyte according to claim 5, characterized in that, In the polymer electrolyte, the total molar number of ethoxy units in monomer A and crosslinking agent B is in a molar ratio of (25-10):1 to the lithium salt.

7. The polymer electrolyte according to claim 5, characterized in that, The lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium tetrafluoroborate, lithium difluorooxalate borate, and lithium dioxalate borate.

8. A solid-state battery, comprising a positive electrode and a negative electrode, characterized in that, It also includes a polymer electrolyte membrane, which comprises the polymer electrolyte as described in any one of claims 5 to 7.

9. The solid-state battery according to claim 8, characterized in that, The thickness of the polymer electrolyte membrane is 20–50 μm.

10. An electrical appliance, characterized in that, Includes the solid-state battery as described in claim 8 or 9, wherein the solid-state battery serves as the power supply for the electrical device.

Images