All-solid-state polymer electrolyte and preparation method and application thereof

Abstract

The invention provides an all-solid-state polymer electrolyte as well as a preparation method and application thereof. The all-solid-state polymer electrolyte is prepared from the following raw materials in parts by weight: 0.5-2 parts of a cross-linking agent B-HEMA, 7 parts of ionic liquid, 2 parts of a sulfone additive and 3 parts of lithium salt. The preparation method comprises the following steps: (1) mixing a cross-linking agent B-HEMA, an ionic liquid, a sulfone additive and a lithium salt for the first time, adding a photoinitiator, and mixing for the second time to obtain a precursor solution; and (2) placing the precursor solution in a mold, and carrying out photopolymerization to obtain the all-solid-state polymer electrolyte. The preparation raw materials of the all-solid-state polymer electrolyte are designed, so that the all-solid-state polymer electrolyte with relatively high ionic conductivity, relatively good high-voltage resistance and relatively good cycling stability is prepared, and the all-solid-state polymer electrolyte can be matched with a 4.4 V lithium cobalt oxide solid-state lithium battery and can realize long-acting stable operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy materials, and in particular relates to an all-solid-state polymer electrolyte and a preparation method and application thereof. Background Art

[0002] The development of high-energy-density energy storage devices is a major challenge facing mankind in the 21st century, and my country has maintained long-term attention and investment in this regard. At present, solid-state lithium batteries are extremely promising next-generation energy storage devices with the potential to achieve high energy density and high safety. The lithium metal anode has a theoretical specific capacity (3860mAh / g) and a low electrode potential (-3.04V vs SHE) that is ten times that of the traditional graphite anode, which can significantly improve the energy density of power batteries. In order to achieve the high energy density of lithium metal batteries, it is necessary to use a combination of high-voltage positive electrode materials and metallic lithium, and to match them with a suitable electrolyte. At present, the research on electrolytes mainly focuses on electrolytes, and the development of polymer electrolytes with high safety, a wide electrochemical window and suitable for high-voltage lithium metal batteries still faces many challenges.

[0003] Currently, there are three common methods for expanding the electrochemical window of polymer electrolyte systems: constructing a stable electrode-electrolyte interface layer, regulating intermolecular interactions, and structural design. To achieve stable charge and discharge of solid-state batteries in the high voltage range, special attention must be paid to the interfacial stability between the solid electrolyte and metallic lithium and the high-voltage positive electrode. Methods for regulating interfacial stability, such as designing anion-rich derivative interfaces, constructing artificial interfacial membranes, using high-concentration lithium salts, and using small molecule additives, all rely on obtaining dense interfacial protection that promotes lithium ion transport. Studies have shown that the interface of inorganic components is conducive to the transport of lithium ions and the protection of electrodes, while the anions in the electrolyte system are conducive to the formation of inorganic interfaces. Therefore, polyionic liquids with excellent antioxidant capacity and rich anions have the potential to match high-voltage positive electrodes and regulate interfaces, and are expected to meet the requirements of next-generation energy storage devices with high safety and high energy density.

[0004] Existing all-solid-state polymer electrolytes have poor high-voltage resistance, and some polymer electrolytes with wide electrochemical windows exhibit poor cycling stability when used in high-voltage solid-state batteries. Furthermore, the preparation of all-solid-state polymer electrolytes is complex and expensive, making them unsuitable for industrial production. Therefore, developing a polymer electrolyte with excellent high-voltage resistance and cycling stability, simple preparation methods, and low production costs has become a pressing technical challenge. Summary of the Invention

[0005] In response to the shortcomings of the prior art, the present invention aims to provide an all-solid-state polymer electrolyte, its preparation method, and its application. By designing the raw materials for preparing the all-solid-state polymer electrolyte and using specific crosslinking agents and additives, the present invention produces an all-solid-state polymer electrolyte with high ionic conductivity, good high-voltage resistance, and excellent cycling stability.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an all-solid-state polymer electrolyte, wherein the raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0008] 0.5-2 parts of cross-linking agent B-HEMA, 5-9 parts of ionic liquid, 0.5-5 parts of sulfone additive and 2-6 parts of lithium salt.

[0009] In the present invention, by designing the raw materials for preparing the all-solid-state polymer electrolyte and using specific cross-linking agents and specific additives, an all-solid-state polymer electrolyte with high ionic conductivity, good high voltage resistance and good cycle stability is prepared.

[0010] In the present invention, the crosslinking agent B-HEMA is an acceptor-type crosslinking agent, which is in situ copolymerized with an ionic liquid, a sulfone additive and a lithium salt to prepare an all-solid-state polymer electrolyte with good electrical properties.

[0011] In the present invention, by controlling the amount of the crosslinking agent B-HEMA within a specific range, an all-solid-state polymer electrolyte with excellent performance is prepared. If the amount of the crosslinking agent B-HEMA is too small, the all-solid-state polymer electrolyte will not fully solidify. If the amount of the crosslinking agent B-HEMA is too large, the prepared all-solid-state polymer electrolyte will have low ionic conductivity, which is not conducive to the efficient transmission of lithium ions during the battery's charge and discharge process.

[0012] In the present invention, sulfone groups are introduced into the all-solid polymer electrolyte by using sulfone additives, thereby improving the ionic conductivity of the all-solid polymer electrolyte.

[0013] In the present invention, the weight proportion of the crosslinking agent B-HEMA in the raw materials for preparing the all-solid-state polymer electrolyte can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts or 2 parts, etc.

[0014] The weight proportion of the ionic liquid in the raw materials for preparing the all-solid-state polymer electrolyte may be 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts or 9 parts, etc.

[0015] The weight proportion of the sulfone additive in the raw materials for preparing the all-solid-state polymer electrolyte can be 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts.

[0016] The weight proportion of lithium salt in the raw materials for preparing the all-solid-state polymer electrolyte may be 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts or 6 parts, etc.

[0017] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0018] As a preferred technical solution of the present invention, the raw materials for preparing the crosslinking agent B-HEMA include the following components: 2-hydroxyethyl methacrylate, trimethyl borate and solvent;

[0019] The molar ratio of the 2-hydroxyethyl methacrylate and trimethyl borate is (2.5-3.5):1, for example, it can be 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1 or 3.5:1.

[0020] In the present invention, by controlling the mass ratio of 2-hydroxyethyl methacrylate and trimethyl borate within a specific range, a cross-linking agent with excellent performance is prepared, and further an all-solid-state polymer electrolyte with excellent electrical performance is prepared.

[0021] Preferably, the solvent comprises anhydrous acetonitrile.

[0022] It should be noted that there is no special limitation on the amount of solvent used in the present invention, and any solvent commonly used in the art is applicable.

[0023] As a preferred technical solution of the present invention, the preparation method of the cross-linking agent B-HEMA comprises the following steps:

[0024] 2-Hydroxyethyl methacrylate, trimethyl borate and a solvent are mixed and reacted to obtain the crosslinking agent B-HEMA.

[0025] Preferably, the reaction is carried out in a glove box.

[0026] The glove box was filled with argon.

[0027] Preferably, the reaction temperature is 50-70°C (for example, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, etc.), and the reaction time is 2-4h (for example, 2h, 2.5h, 3h, 3.5h or 4h, etc.).

[0028] Preferably, the reaction further includes a post-treatment step, and the post-treatment method includes: heating to 70°C, heating for 3 to 5 hours (for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours, etc.), removing the by-product methanol, and then distilling under reduced pressure at 50 to 70°C (for example, 50°C, 52°C, 55°C, 57°C, 60°C, 63°C, 66°C, 68°C or 70°C, etc.) to remove unreacted reactants and residual solvent, and vacuum drying for 24 to 72 hours (for example, 24 hours, 36 hours, 48 ​​hours, 60 hours or 72 hours, etc.).

[0029] Preferably, the preparation method of the cross-linking agent B-HEMA specifically comprises the following steps:

[0030] In an argon-filled glove box, 2-hydroxyethyl methacrylate, trimethyl borate and a solvent are mixed, reacted at 50-70° C. for 2-4 hours, then heated to 70° C. and heated for 3-5 hours. Under an inert gas purge, the by-product methanol is removed, and then the mixture is subjected to reduced pressure distillation at 50-70° C. to remove unreacted reactants and residual solvent, and vacuum dried for 24-72 hours to obtain the crosslinking agent B-HEMA.

[0031] As a preferred technical solution of the present invention, the ionic liquid is selected from any one of imidazolium-type ionic liquids, pyridinium-type ionic liquids, pyrrole-type ionic liquids, quaternary ammonium salt-type ionic liquids or quaternary phosphonium salt ionic liquids, or a combination of at least two thereof.

[0032] Preferably, the ionic liquid is selected from imidazolium-type ionic liquids and / or pyrrole-type ionic liquids.

[0033] As a preferred technical solution of the present invention, the sulfone additive is selected from any one or a combination of at least two of 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), 3-cyclobutene sulfone-3-methyl ester, 3-cyclobutene sulfone, bis(4-fluorophenyl)sulfone or phenyl vinyl sulfone.

[0034] As a preferred technical solution of the present invention, the lithium salt is selected from any one or a combination of at least two of LiTFSi, NaTFSi, LiPF6, NaPF6, LiFSI, NaFSI, LiClO4, LiBF4, LiDFOB or LiBOB.

[0035] As a preferred technical solution of the present invention, taking the mass percentage of the raw materials for preparing the all-solid-state polymer electrolyte as 100%, the raw materials for preparing the all-solid-state polymer electrolyte also include a photoinitiator with a mass percentage of 0.5 to 1% (for example, it can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, etc.).

[0036] Preferably, the photoinitiator is selected from any one or a combination of at least two of the initiator IRGACURE 819, azobisisoheptanonitrile (ABVN), dimethyl azobisisobutyrate (AIBME), azobisisobutylamidine hydrochloride (AIBA), azobisisobutylimidazoline hydrochloride (AIBI) or azoisobutylcyanamide (V30).

[0037] In a second aspect, the present invention provides a method for preparing the all-solid-state polymer electrolyte as described in the first aspect, the preparation method comprising the following steps:

[0038] (1) After a first mixing of a crosslinking agent B-HEMA, an ionic liquid, a sulfone additive, and a lithium salt, a photoinitiator is added thereto and mixed for a second time to obtain a precursor solution;

[0039] (2) placing the precursor solution in a mold and performing photopolymerization to obtain the all-solid-state polymer electrolyte.

[0040] As a preferred technical solution of the present invention, the precursor solution is prepared in a glove box.

[0041] Preferably, the first mixing and the second mixing are both performed in a brown container.

[0042] Preferably, the first mixing time is 1 to 3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.

[0043] Preferably, the second mixing time is 20 to 60 min, for example, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min.

[0044] Preferably, the photopolymerization time is 5 to 10 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes.

[0045] It should be noted that the photopolymerization is carried out in the presence of ultraviolet light.

[0046] The preparation method of the all-solid-state polymer electrolyte specifically comprises the following steps:

[0047] (1) In a glove box, a crosslinker B-HEMA, an ionic liquid, a sulfone additive, and a lithium salt are placed in a brown container and mixed for a first time for 1 to 3 hours, and then a photoinitiator is added thereto and mixed for a second time for 20 to 60 minutes to obtain a precursor solution;

[0048] (2) placing the precursor solution in a mold and performing photopolymerization under ultraviolet light for 5 to 10 minutes to obtain the all-solid-state polymer electrolyte.

[0049] In a third aspect, the present invention provides a solid-state lithium battery, comprising the all-solid-state polymer electrolyte as described in the first aspect.

[0050] The present invention does not impose any particular limitation on the preparation method of lithium-ion batteries. Common preparation methods in the art are applicable, including but not limited to:

[0051] (A) The membrane was cut into 19 mm diameter discs, dried in an oven, and placed in a glove box until ready for use.

[0052] Placing the separator on the positive electrode sheet in the positive electrode shell, and dripping the precursor solution provided in step (1) so that the positive electrode sheet and the separator are completely immersed in the precursor solution, and irradiating with ultraviolet light to perform photopolymerization for 5 to 10 minutes to obtain a fully solid polymer electrolyte;

[0053] (B) A negative electrode sheet, a steel sheet, a spring, and a negative electrode shell are sequentially placed on the side of the all-solid-state polymer electrolyte away from the positive electrode sheet to assemble a solid-state lithium battery.

[0054] Preferably, the separator comprises a cellulose separator, and the negative electrode sheet comprises any one of a lithium negative electrode sheet, a magnesium negative electrode sheet, an aluminum negative electrode sheet or a sodium negative electrode sheet.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] In the present invention, by designing the raw materials for preparing the all-solid-state polymer electrolyte, using a specific crosslinking agent and specific additives, and controlling the amount of the crosslinking agent B-HEMA within a specific range, an all-solid-state polymer electrolyte with high ionic conductivity, good high-voltage resistance, and good cycle stability is prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is a complex plane diagram of ionic conductivity of a solid-state lithium battery assembled with the all-solid-state polymer electrolyte provided in Example 1;

[0058] Figure 2 This is an electrochemical window test diagram of a solid-state lithium battery assembled with the all-solid-state polymer electrolyte provided in Example 1;

[0059] Figure 3 This is a test chart of the capacity retention rate of a solid-state lithium battery assembled with the all-solid-state polymer electrolyte provided in Example 1;

[0060] Figure 4 This is a charge and discharge curve test diagram of a solid-state lithium battery assembled with the all-solid-state polymer electrolyte provided in Example 1. DETAILED DESCRIPTION

[0061] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0062] The sources of some components in the following examples and comparative examples are as follows:

[0063] Cellulose separator: purchased from NKK, Japan, brand TF4040, cut into discs with a diameter of 17-20 mm.

[0064] Pyrrole-type ionic liquid: allylpyrrolidinium bis(trifluoromethanesulfonyl)imide.

[0065] Preparation Example 1

[0066] This preparation example provides a cross-linking agent B-HEMA, and the preparation method of the cross-linking agent B-HEMA is as follows:

[0067] In an argon-filled glove box, 2-hydroxyethyl methacrylate (3 mol) and trimethyl borate (1 mol) were reacted at 55° C. with anhydrous acetonitrile (20 mL) as a solvent for 3 h. The reaction was then heated to 70° C. and heated for 4 h. The by-product methanol was removed under argon purge, and the unreacted reactants and residual solvent were removed by reduced pressure distillation at 55° C. The mixture was then vacuum dried for 48 h to obtain the crosslinking agent B-HEMA.

[0068] Preparation Example 2

[0069] This preparation example provides a cross-linking agent B-HEMA, and the preparation method of the cross-linking agent B-HEMA is as follows:

[0070] In an argon-filled glove box, 2-hydroxyethyl methacrylate (3.5 mol) and trimethyl borate (1 mol) were reacted at 55° C. with anhydrous acetonitrile (20 mL) as a solvent for 2 h. The reaction was then heated to 70° C. and heated for 5 h. The by-product methanol was removed under argon purge, and the unreacted reactants and residual solvent were removed by reduced pressure distillation at 65° C. The mixture was then vacuum dried for 30 h to obtain the crosslinking agent B-HEMA.

[0071] Preparation Example 3

[0072] This preparation example provides a cross-linking agent B-HEMA, and the preparation method of the cross-linking agent B-HEMA is as follows:

[0073] In an argon-filled glove box, 2-hydroxyethyl methacrylate (2.5 mol) and trimethyl borate (1 mol) were reacted at 55° C. with anhydrous acetonitrile (20 mL) as a solvent for 4 h. The reaction was then heated to 70° C. and heated for 3 h. The by-product methanol was removed under argon purge, and the unreacted reactants and residual solvent were removed by reduced pressure distillation at 60° C. The mixture was then vacuum dried for 72 h to obtain the crosslinking agent B-HEMA.

[0074] Preparation Example 4

[0075] This preparation example provides a cross-linking agent B-HEMA, and the preparation method of the cross-linking agent B-HEMA is as follows:

[0076] In an argon-filled glove box, 2-hydroxyethyl methacrylate (3.1 mol) and trimethyl borate (1 mol) were reacted at 55° C. with anhydrous acetonitrile (20 mL) as a solvent for 3 h. The reaction was then heated to 70° C. and heated for 4 h. The by-product methanol was removed under argon purge, and the unreacted reactants and residual solvent were removed by reduced pressure distillation at 55° C. The mixture was then vacuum dried for 60 h to obtain the crosslinking agent B-HEMA.

[0077] Example 1

[0078] This embodiment provides an all-solid-state polymer electrolyte and a preparation method thereof. The raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0079] 0.5 parts of the cross-linking agent B-HEMA provided in Preparation Example 1, 7 parts of pyrrole-type ionic liquid, 2 parts of 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), and 3 parts of LiTFSI;

[0080] Based on the mass percentage of the raw materials for preparing the all-solid-state polymer electrolyte being 100%, the raw materials for preparing the all-solid-state polymer electrolyte further include 0.5 mass percentage of initiator IRGACURE 819.

[0081] The preparation method of the all-solid-state polymer electrolyte is as follows:

[0082] (1) In a glove box, the crosslinker B-HEMA, ionic liquid, 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), and LiTFSI were placed in a brown bottle and mixed for 1 h. Then, the initiator IRGACURE 819 was added and mixed for a second time for 30 min to obtain a precursor solution.

[0083] (2) A cellulose separator is placed on the positive electrode sheet in the positive electrode shell, a precursor solution is added dropwise thereto, and photopolymerization is performed under ultraviolet light for 10 minutes to obtain the all-solid-state polymer electrolyte.

[0084] Example 2

[0085] This embodiment provides an all-solid-state polymer electrolyte and a preparation method thereof. The raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0086] 1 part of the crosslinking agent B-HEMA provided in Preparation Example 2, 7 parts of pyrrole-type ionic liquid, 2 parts of 3-cyclobutene sulfone, and 3 parts of LiTFSi;

[0087] Based on the mass percentage of the raw materials for preparing the all-solid-state polymer electrolyte being 100%, the raw materials for preparing the all-solid-state polymer electrolyte further include 0.7 mass percentage of initiator IRGACURE 819.

[0088] The preparation method of the all-solid-state polymer electrolyte is as follows:

[0089] (1) In a glove box, the crosslinker B-HEMA, ionic liquid, 3-cyclobutene sulfone (SE), and LiFSI were placed in a brown bottle and mixed for 2 h. Then, the initiator IRGACURE 819 was added and mixed for a second time for 40 min to obtain a precursor solution.

[0090] (2) A cellulose separator is placed on the positive electrode sheet in the positive electrode shell, a precursor solution is added dropwise thereto, and photopolymerization is performed under ultraviolet light for 7 minutes to obtain the all-solid-state polymer electrolyte.

[0091] Example 3

[0092] This embodiment provides an all-solid-state polymer electrolyte and a preparation method thereof. The raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0093] 2 parts of the cross-linking agent B-HEMA provided in Preparation Example 3, 7 parts of pyrrole-type ionic liquid, 2 parts of 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), and 3 parts of LiFSI;

[0094] Taking the mass percentage of the raw materials for preparing the all-solid polymer electrolyte as 100%, the raw materials for preparing the all-solid polymer electrolyte further include 0.5-1 mass percentage of initiator IRGACURE 819.

[0095] The preparation method of the all-solid-state polymer electrolyte is as follows:

[0096] (1) In a glove box, the crosslinker B-HEMA, ionic liquid, 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), and LiFSI were placed in a brown bottle and mixed for 3 h. Then, the initiator IRGACURE 819 was added and mixed for a second time for 60 min to obtain a precursor solution.

[0097] (2) A cellulose separator is placed on the positive electrode sheet in the positive electrode shell, a precursor solution is added dropwise thereto, and photopolymerization is performed under ultraviolet light for 8 minutes to obtain the all-solid-state polymer electrolyte.

[0098] Example 4

[0099] This embodiment provides an all-solid-state polymer electrolyte and a preparation method thereof. The raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0100] 1 part of the crosslinking agent B-HEMA provided in Preparation Example 4, 5 parts of pyrrole-type ionic liquid, 0.5 parts of bis(4-fluorophenyl)sulfone or phenyl vinylsulfone, and 2 parts of LiTFSi;

[0101] Based on the mass percentage of the raw materials for preparing the all-solid-state polymer electrolyte being 100%, the raw materials for preparing the all-solid-state polymer electrolyte further include 0.7 mass percentage of initiator IRGACURE 819.

[0102] The preparation method of the all-solid-state polymer electrolyte is as follows:

[0103] (1) In a glove box, the crosslinker B-HEMA, ionic liquid, bis(4-fluorophenyl)sulfone or phenyl vinylsulfone (SE), and LiTFSi were placed in a brown bottle and mixed for 2 h. Then, the initiator IRGACURE 819 was added and mixed for a second time for 40 min to obtain a precursor solution.

[0104] (2) A cellulose separator is placed on the positive electrode sheet in the positive electrode shell, a precursor solution is added dropwise thereto, and photopolymerization is performed under ultraviolet light for 7 minutes to obtain the all-solid-state polymer electrolyte.

[0105] Example 5

[0106] This embodiment provides an all-solid-state polymer electrolyte and a preparation method thereof. The raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0107] 2 parts of the cross-linking agent B-HEMA provided in Preparation Example 3, 9 parts of pyrrole-type ionic liquid, 5 parts of methyl 3-cyclobutene sulfone-3-carboxylate, and 6 parts of LiFSI;

[0108] Taking the mass percentage of the raw materials for preparing the all-solid polymer electrolyte as 100%, the raw materials for preparing the all-solid polymer electrolyte further include 0.5-1 mass percentage of initiator IRGACURE 819.

[0109] The preparation method of the all-solid-state polymer electrolyte is as follows:

[0110] (1) In a glove box, the crosslinker B-HEMA, ionic liquid, 3-cyclobutene sulfone-3-methyl ester (SE), and LiFSI were placed in a brown bottle and mixed for 3 h. Then, the initiator IRGACURE 819 was added and mixed for a second time for 60 min to obtain a precursor solution.

[0111] (2) A cellulose separator is placed on the positive electrode sheet in the positive electrode shell, a precursor solution is added dropwise thereto, and photopolymerization is performed under ultraviolet light for 8 minutes to obtain the all-solid-state polymer electrolyte.

[0112] Example 6

[0113] This embodiment provides an all-solid-state polymer electrolyte and a preparation method thereof. The only difference from Example 1 is that the raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0114] 1 part of the cross-linking agent B-HEMA provided in Preparation Example 1, 7 parts of pyrrole-type ionic liquid, 2 parts of 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), and 3 parts of LiFSI;

[0115] Other conditions are the same as in Example 1.

[0116] Example 7

[0117] This embodiment provides an all-solid-state polymer electrolyte and a preparation method thereof. The only difference from Example 1 is that the raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0118] 2 parts of the cross-linking agent B-HEMA provided in Preparation Example 1, 7 parts of pyrrole-type ionic liquid, 2 parts of 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), and 3 parts of LiFSI;

[0119] Other conditions are the same as in Example 1.

[0120] Comparative Example 1

[0121] This comparative example provides an all-solid-state polymer electrolyte and a preparation method thereof. The only difference from Example 1 is that the raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0122] 0.2 parts of the cross-linking agent B-HEMA provided in Preparation Example 1, 7 parts of pyrrole-type ionic liquid, 2 parts of 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), and 3 parts of LiFSI;

[0123] Other conditions are the same as in Example 1.

[0124] Comparative Example 2

[0125] This comparative example provides an all-solid-state polymer electrolyte and a preparation method thereof. The only difference from Example 1 is that the raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0126] 4 parts of the cross-linking agent B-HEMA provided in Preparation Example 1, 7 parts of pyrrole-type ionic liquid, 2 parts of 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), and 3 parts of LiFSI;

[0127] Other conditions are the same as in Example 1.

[0128] Comparative Example 3

[0129] This comparative example provides an all-solid-state polymer electrolyte and a preparation method thereof. The only difference from Example 1 is that the raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0130] 4 parts of dimethacrylate, 7 parts of pyrrole-type ionic liquid, 2 parts of 2-amino-N-ethyl-N-phenylbenzenesulfonamide (SE), and 3 parts of LiFSI;

[0131] Other conditions are the same as in Example 1.

[0132] Comparative Example 4

[0133] This comparative example provides an all-solid-state polymer electrolyte and a preparation method thereof. The only difference from Example 1 is that the raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight:

[0134] 4 parts of the cross-linking agent B-HEMA provided in Preparation Example 1, 7 parts of pyrrole-type ionic liquid, 2 parts of succinonitrile (SN), and 3 parts of LiFSI;

[0135] Other conditions are the same as in Example 1.

[0136] The all-solid-state polymer electrolytes provided in the above embodiments and comparative examples are respectively assembled into solid-state lithium batteries. The specific assembly method is as follows: a lithium negative electrode sheet, a steel sheet, a spring sheet, and a negative electrode shell are placed in sequence on the side of the all-solid-state polymer electrolyte provided in the above embodiments and comparative examples away from the positive electrode sheet to assemble a solid-state lithium battery.

[0137] The performance of the lithium cobalt oxide solid-state lithium battery assembled with the all-solid-state polymer electrolyte provided by the above embodiments and comparative examples was tested. The specific testing method is as follows:

[0138] (1) Ionic conductivity: The ionic conductivity of the samples was measured on a symmetrical SS|polymer electrolyte|SS cell, where SS served as the ion-blocking electrode. The symmetrical cell was tested using an electrochemical workstation with a frequency range of 0.1 Hz to 7 MHz and an amplitude of 10 mV. The conductivity (σ) was calculated as follows: σ = L / (RS), where L is the thickness of the electrolyte membrane, R is the electrolyte resistance, and S is the effective electrode surface area.

[0139] (2) Electrochemical window: Linear sweep voltammetry (LSV) was used to measure the electrochemical window of the polymer electrolyte and evaluate its electrochemical stability. SS|polymer electrolyte|Li battery was assembled and tested at 0.1 mV·s -1 The rate was scanned from 0 V to 6 V on the electrochemical workstation.

[0140] (3) Capacity retention: The electrochemical performance of the Li|polymer electrolyte|LCO battery was tested using a Neware BTS battery tester. The lithium cobalt oxide solid-state lithium battery was cycled for two cycles at 0.1C and then subjected to a long cycle at 0.5C with a charge and discharge cutoff voltage of 3.0-4.4V. The capacity retention after 200 cycles was calculated.

[0141] The ionic conductivity test complex plane diagram of the solid-state lithium battery assembled by the all-solid-state polymer electrolyte provided in Example 1 is as follows Figure 1 As shown, the horizontal axis is the real part of the impedance complex plane diagram, and the vertical axis is the imaginary part of the impedance complex plane diagram, which is given by Figure 1 According to the calculation formula, its ionic conductivity is 4.2×10 -4 S cm -1 .

[0142] The electrochemical window test diagram of the solid-state lithium battery assembled with the all-solid-state polymer electrolyte provided in Example 1 is as follows: Figure 2 As shown by Figure 2 It can be seen that its electrochemical window is 5.55V.

[0143] The long cycle test of the solid-state lithium battery assembled with the all-solid-state polymer electrolyte provided in Example 1 is shown in FIG. Figure 3 As shown by Figure 3 It can be seen that the capacity retention rate after 200 cycles is 97.0%.

[0144] The charge and discharge curve test diagram of the solid-state lithium battery assembled with the all-solid-state polymer electrolyte provided in Example 1 is as follows: Figure 4 As shown by Figure 4It can be seen that the battery has less polarization at 0.5C and can be charged and discharged stably for a long time.

[0145] The test results are shown in Table 1 below:

[0146] Table 1

[0147] <![CDATA[Ionic conductivity / S cm -1 > Electrochemical window / V Capacity retention rate / % Example 1 <![CDATA[4.2×10 -4 ]]> 5.55 97.0 Example 2 <![CDATA[3.6×10 -4 ]]> 5.55 98.8 Example 3 <![CDATA[1.6×10 -4 ]]> 5.50 96.0 Example 4 <![CDATA[1.0×10 -4 ]]> 5.30 95.0 Example 5 <![CDATA[1.8×10 -4 ]]> 5.50 97.3 Example 6 <![CDATA[2.8×10 -4 ]]> 5.55 96.1 Example 7 <![CDATA[1.1×10 -4 ]]> 5.40 97.0 Comparative Example 1 <![CDATA[2.8×10 -4 ]]> 5.50 56.9 Comparative Example 2 <![CDATA[1.4×10 -5 ]]> 5.10 35.3 Comparative Example 3 <![CDATA[5.8×10 -5 ]]> 5.30 21.8 Comparative Example 4 <![CDATA[2.0×10 -4 ]]> 5.00 47.1

[0148] From the above, it can be seen that in the present invention, by designing the raw materials for preparing the all-solid-state polymer electrolyte, using a specific cross-linking agent and a specific additive, and controlling the amount of the cross-linking agent B-HEMA within a specific range, an all-solid-state polymer electrolyte with high ionic conductivity, good high voltage resistance, and good cycle stability is prepared. The ionic conductivity is (1.0-4.2)×10 -4 S cm -1 The electrochemical window is 5.30~5.55V, and the capacity retention rate is 95.0~98.8%.

[0149] If the amount of cross-linking agent used in the preparation raw materials of the all-solid-state polymer electrolyte is too small (Comparative Example 1), the all-solid-state polymer electrolyte will not be completely cured, and the performance of the solid-state lithium battery obtained will be poor; if the amount of cross-linking agent used in the preparation raw materials of the all-solid-state polymer electrolyte is too large (Comparative Example 2), the ionic conductivity of the solid-state lithium battery obtained by the all-solid-state polymer electrolyte will be low, which is not conducive to the effective transmission of lithium ions during the battery charging and discharging process.

[0150] If other types of cross-linking agents (Comparative Example 3) or other types of additives (Comparative Example 4) are used to prepare all-solid-state polymer electrolytes, the performance of the solid-state lithium batteries prepared therefrom is poor.

[0151] In summary, in the present invention, an all-solid-state polymer electrolyte with high ionic conductivity, good high voltage resistance and good cycle stability is obtained by designing and preparing the raw materials for preparing the all-solid-state polymer electrolyte.

[0152] The applicant declares that the present invention uses the above-described embodiments to illustrate the detailed process flow of the present invention, but the present invention is not limited to the above-described detailed process flow, that is, it does not mean that the present invention must rely on the above-described detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for various raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. An all-solid-state polymer electrolyte, characterized in that: The raw materials for preparing the all-solid-state polymer electrolyte include the following components in parts by weight: 0.5-2 parts of cross-linking agent B-HEMA, 5-9 parts of ionic liquid, 0.5-5 parts of sulfone additive and 2-6 parts of lithium salt.

2. The all-solid-state polymer electrolyte according to claim 1, characterized in that The raw materials for preparing the cross-linking agent B-HEMA include the following components: 2-hydroxyethyl methacrylate, trimethyl borate and solvent; The molar ratio of 2-hydroxyethyl methacrylate to trimethyl borate is (2.5-3.5):1; Preferably, the solvent comprises anhydrous acetonitrile.

3. The all-solid-state polymer electrolyte according to claim 2, characterized in that The preparation method of the cross-linking agent B-HEMA comprises the following steps: 2-hydroxyethyl methacrylate, trimethyl borate and a solvent are mixed and reacted to obtain the crosslinking agent B-HEMA; Preferably, the reaction is carried out in a glove box; Preferably, the reaction temperature is 50-70° C., and the reaction time is 2-4 h; Preferably, the reaction further includes a post-treatment step, and the post-treatment method includes: heating to 70° C., heating for 3 to 5 hours, removing the by-product methanol, and then distilling under reduced pressure at 50 to 70° C. to remove unreacted reactants and residual solvent, and vacuum drying for 24 to 72 hours.

4. The all-solid-state polymer electrolyte according to any one of claims 1 to 3, characterized in that: The ionic liquid is selected from any one or a combination of at least two of imidazolium ionic liquids, pyridinium ionic liquids, pyrrole ionic liquids, quaternary ammonium salt ionic liquids or quaternary phosphonium salt ionic liquids; Preferably, the ionic liquid is selected from imidazolium-type ionic liquids and / or pyrrole-type ionic liquids.

5. The all-solid-state polymer electrolyte according to any one of claims 1 to 4, characterized in that: The sulfone additive is selected from any one or a combination of at least two of 2-amino-N-ethyl-N-phenylbenzenesulfonamide, 3-cyclobutene sulfone-3-methyl ester, 3-cyclobutene sulfone, bis(4-fluorophenyl)sulfone or phenyl vinyl sulfone.

6. The all-solid-state polymer electrolyte according to any one of claims 1 to 5, characterized in that: The lithium salt is selected from any one or a combination of at least two of LiTFSi, NaTFSi, LiPF6, NaPF6, LiFSI, NaFSI, LiClO4, LiBF4, LiDFOB or LiBOB.

7. The all-solid-state polymer electrolyte according to any one of claims 1 to 6, characterized in that: The raw materials for preparing the all-solid polymer electrolyte further comprise a photoinitiator in an amount of 0.5 to 1% by weight, based on the mass percentage of the raw materials for preparing the all-solid polymer electrolyte being 100%; Preferably, the photoinitiator is selected from any one of initiator IRGACURE 819, azobisisoheptanenitrile, dimethyl azobisisobutyrate, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride or azoisobutylcyanamide, or a combination of at least two thereof.

8. A method for preparing an all-solid-state polymer electrolyte according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: (1) After a first mixing of a crosslinking agent B-HEMA, an ionic liquid, a sulfone additive, and a lithium salt, a photoinitiator is added thereto and mixed for a second time to obtain a precursor solution; (2) placing the precursor solution in a mold and performing photopolymerization to obtain the all-solid-state polymer electrolyte.

9. The method for preparing an all-solid-state polymer electrolyte according to claim 8, wherein: The precursor solution is prepared in a glove box; Preferably, the first mixing time is 1 to 3 hours; Preferably, the second mixing time is 20 to 60 minutes; Preferably, the photopolymerization time is 5 to 10 minutes.

10. A solid-state lithium battery, characterized in that: The solid-state lithium battery comprises the all-solid-state polymer electrolyte according to any one of claims 1 to 7.

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