Insulating film for solid-state battery as well as preparation method and application of insulating film

Abstract

The invention discloses an insulating film for a solid-state battery as well as a preparation method and application of the insulating film, and belongs to the technical field of battery materials. The insulating film comprises modified poly (allyl carbonate), the modified poly (allyl carbonate) comprises a thermosensitive group, the thermosensitive group is selected from at least one of t-butyloxycarboryl, azodicarbonyl, sulfonyl azide, tert-butyl carbonate and nitryl, and the thermal decomposition temperature of the modified poly (allyl carbonate) is 120-150 DEG C due to the doping amount of the thermosensitive group. By adopting the insulating film, the intrinsic breakdown voltage of the solid-state battery can be improved, the risk that the solid-state battery is broken down during a high-potential test is effectively avoided, the insulating film is convenient to remove after the test, and the quality and the charge-discharge performance of the solid-state battery are ensured.

Description

Technical Field

[0001] This application relates to the technical field of battery materials, and particularly to an insulating film for a solid-state battery, a preparation method thereof, and an application thereof. Background Art

[0002] Hi-pot (High Potential) test is a test method for testing the insulation performance of a battery by applying a high-potential voltage, which can detect defects such as cracks and impurities in the battery and can be used to determine the potential internal short-circuit risk of the battery.

[0003] For a solid-state battery, since the solid electrolyte inside it is not completely insulating to electrons, when detected by Hi-pot test, a relatively high test voltage is required, resulting in a risk of breakdown of the solid-state battery. In related technologies, an insulating layer is usually inserted into the solid-state battery to increase the intrinsic breakdown voltage of the solid-state battery to avoid breakdown of the solid-state battery during Hi-pot test.

[0004] However, the insertion of the insulating layer will reduce the ion conduction efficiency of the solid-state battery, increase the internal resistance of the solid-state battery, and affect the charge and discharge performance of the solid-state battery. Summary of the Invention

[0005] This application provides an insulating film for a solid-state battery, a preparation method thereof, and an application thereof to solve the technical problems existing in the related technologies. Specifically, the following technical solutions are included.

[0006] In a first aspect, this application provides an insulating film for a solid-state battery, the insulating film includes modified polyallyl carbonate, the modified polyallyl carbonate includes a thermosensitive group, the thermosensitive group is selected from at least one of tert-butoxycarbonyl, azodicarboxylate, sulfonyl azide, tert-butyl carbonate, and nitro, and the doping amount of the thermosensitive group makes the thermal decomposition temperature of the modified polyallyl carbonate be 120°C - 150°C, for example, it can be 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, 132°C, 134°C, 136°C, 138°C, 140°C, 142°C, 144°C, 146°C, 148°C, 150°C, etc., or other values within the above range.

[0007] In some possible embodiments, the doping percentage of the thermosensitive group in the modified polyallyl carbonate is 10%-30%, for example, it can be 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, etc., or other values within the above range.

[0008] In some possible embodiments, the electronic impedance of the insulating film is greater than 1.0×10 15 Ω / cm, and the electronic impedance of the insulating film can be, for example, 1.1×10 15 Ω / cm, 1.2×10 15 Ω / cm, 1.3×10 15 Ω / cm, 1.4×10 15 Ω / cm, 1.5×10 15 Ω / cm, 1.6×10 15 Ω / cm, 1.7×10 15 Ω / cm, 1.8×10 15 Ω / cm, 1.9×10 15 Ω / cm, 2.0×10 15 Ω / cm, 2.1×10 15 Ω / cm, 2.2×10 15 Ω / cm, 2.3×10 15 Ω / cm, 2.4×10 15 Ω / cm, 2.5×10 15 Ω / cm, 2.6×10 15 Ω / cm, 2.7×10 15 Ω / cm, etc., or other values within the above range, and the present application does not make any restrictions in this regard.

[0009] In some possible embodiments, the thickness of the insulating film is 5μm - 30μm.

[0010] In a second aspect, the present application provides a method for preparing an insulating film, the method comprising: preparing a modified polyallyl carbonate, the modified polyallyl carbonate comprising a thermosensitive group selected from at least one of tert-butoxycarbonyl, azodicarboxylate, sulfonyl azide, tert-butyl carbonate, and nitro, and the doping amount of the thermosensitive group is such that the thermal decomposition temperature of the modified polyallyl carbonate is 120°C - 150°C; preparing the insulating film from the modified polyallyl carbonate through a film-forming process.

[0011] In a third aspect, the present application provides a solid-state battery, which includes a positive electrode sheet, a negative electrode sheet, a solid electrolyte, and an insulating film as described in any one of the first aspects of the present application; the insulating film is located between at least one of the positive electrode sheet and the negative electrode sheet and the solid electrolyte.

[0012] In some possible embodiments, the insulating film is located between the positive electrode sheet and the solid electrolyte.

[0013] In some possible embodiments, the insulating film is located between the negative electrode sheet and the solid electrolyte.

[0014] In a fourth aspect, the present application provides a method for testing the insulation performance of a solid-state battery, the method including: testing the solid-state battery through a high-potential testing process, wherein the solid-state battery uses the solid-state battery as described in any one of the first aspects of the present application; performing heat preservation treatment on the tested solid-state battery at 120°C - 150°C.

[0015] In some possible embodiments, the duration of the heat preservation treatment is 30 min - 60 min.

[0016] The beneficial effects of the technical solutions provided by the present application at least include:

[0017] For the insulating film of the solid-state battery provided by the present application, by introducing specific thermosensitive groups into polyallyl carbonate, on the one hand, the insulating film retains the excellent electronic insulation performance of polyallyl carbonate, and on the other hand, the thermosensitive groups introduced into the modified polyallyl carbonate can make the insulating film show the characteristic of poor thermal stability and be easily decomposed at 120°C - 150°C. In particular, by selecting specific thermosensitive groups in the embodiments of the present application, there are no moisture and other solid residues after the insulating film is thermally decomposed. When the above insulating film is applied to a solid-state battery, especially in the high-potential testing field of a solid-state battery, it can improve the intrinsic breakdown voltage of the solid-state battery, effectively avoid the risk of the solid-state battery being broken down, and facilitate the removal of the insulating film after testing, which is beneficial to improving the charge and discharge performance of the solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 is a schematic structural diagram of the solid-state battery provided by the embodiment of the present application;

[0020] Figure 2 It is a schematic structural diagram of another solid-state battery provided by an embodiment of the present application. Detailed implementation manners

[0021] Internal short circuit in a solid-state battery refers to the situation where an undesired direct or indirect connection occurs between the positive electrode and the negative electrode inside the solid-state battery, resulting in the current bypassing the normal working circuit of the battery and directly flowing through the short-circuit point. For example, defects, cracks, voids, or impurities existing in the solid electrolyte inside the solid-state battery form abnormal conduction paths for electrons, leading to the formation of a short-circuit channel inside the solid-state battery.

[0022] Internal short circuit will seriously affect the electrical performance of the solid-state battery and increase the risk of thermal runaway of the solid-state battery. In view of this, in order to reduce the impact of internal short circuit on the solid-state battery, an insulating layer can be inserted into the solid-state battery so that the internal short circuit situation of the solid-state battery can be detected through high-potential testing. However, the insertion of the insulating layer will also reduce the ion conduction efficiency of the solid-state battery, increase the internal resistance of the solid-state battery, and affect the charge and discharge performance of the solid-state battery.

[0023] Aiming at the technical problem that after inserting an insulating layer into a solid-state battery to improve its insulation performance, the charge and discharge performance of the solid-state battery will be affected, the present application provides an insulating film for a solid-state battery, which can not only improve the insulation performance of the solid-state battery, but also be removed by thermal decomposition according to the needs of actual applications to ensure the charge and discharge performance of the solid-state battery. In particular, the products after thermal decomposition of the insulating film have no moisture and solid residues.

[0024] The first aspect of the present application discloses an insulating film for a solid-state battery. The insulating film includes modified polyallyl carbonate, and the modified polyallyl carbonate includes a thermosensitive group. The thermosensitive group is selected from at least one of tert-butoxycarbonyl, azodicarboxylate, sulfonyl azide, tert-butyl carbonate, and nitro. The doping amount of the thermosensitive group makes the thermal decomposition temperature of the modified polyallyl carbonate be 120°C - 150°C.

[0025] Among them, polyallyl carbonate can be used to provide good insulation performance for, but not limited to, modified polyallyl carbonate and the insulating film, so that when the insulating film is used in a solid-state battery, the insulation performance inside the solid-state battery can be effectively improved, thereby increasing the intrinsic breakdown voltage of the solid-state battery (that is, the maximum electric field strength or voltage value that the inside of the solid-state battery can withstand without the influence of non-ideal factors such as external defects), so as to prevent the solid-state battery from being broken down during high-potential testing with a relatively high test voltage.

[0026] The thermosensitive group can be used for, but not limited to, improving the thermosensitivity of the modified polyallyl carbonate and the insulating film, so that the insulating film has the characteristic of being easily decomposed by heat. Furthermore, when the insulating film is used in a solid-state battery, it can be removed according to the needs of the actual application situation to ensure the charge and discharge performance of the solid-state battery.

[0027] Optionally, the thermosensitive group can be selected from at least one of tert-butoxycarbonyl, azodicarboxylate, sulfonyl azide, tert-butyl carbonate, and nitro, so that there is no moisture and solid residue after the insulating film is decomposed by heat. For example, when the thermosensitive group is tert-butoxycarbonyl, after the insulating film is heated, the carbonate bond in the modified polyallyl carbonate is broken, generating carbon dioxide and allyl ether gases; when the thermosensitive group is azodicarboxylate, after the insulating film is heated, the carbonate bond in the modified polyallyl carbonate is broken, generating carbon dioxide and allyl ether gases; when the thermosensitive group is sulfonyl azide, after the insulating film is heated, the decomposition products are nitrogen and sulfur dioxide; when the thermosensitive group is tert-butyl carbonate, after the insulating film is heated, the decomposition products are carbon dioxide and isobutene; when the thermosensitive group is nitro, after the insulating film is heated, the decomposition products are nitrogen dioxide and nitric oxide.

[0028] In some embodiments, the doping amount of the thermosensitive group in the modified polyallyl carbonate makes the thermal decomposition temperature of the modified polyallyl carbonate be 120°C - 150°C. For example, it can be 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, 132°C, 134°C, 136°C, 138°C, 140°C, 142°C, 144°C, 146°C, 148°C, 150°C, etc., or other values within the above range.

[0029] In some embodiments, the doping mass percentage of the thermosensitive group in the modified polyallyl carbonate is 10wt% - 30wt%. For example, it can be 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, etc., or other values within the above range.

[0030] Exemplarily, in order to make the solid-state battery exhibit good insulation performance, the electronic impedance of the insulating film is greater than 1.0×10 15 Ω / cm. The electronic impedance of the insulating film can be, for example, 1.1×10 15 Ω / cm, 1.2×10 15 Ω / cm, 1.3×10 15 Ω / cm, 1.4×10 15 Ω / cm, 1.5×1015 Ω / cm, 1.6×10 15 Ω / cm, 1.7×10 15 Ω / cm, 1.8×10 15 Ω / cm, 1.9×10 15 Ω / cm, 2.0×10 15 Ω / cm, 2.1×10 15 Ω / cm, 2.2×10 15 Ω / cm, 2.3×10 15 Ω / cm, 2.4×10 15 Ω / cm, 2.5×10 15 Ω / cm, 2.6×10 15 Ω / cm, 2.7×10 15 Ω / cm, etc., or other values within the above range, and the present application does not make any restrictions in this regard.

[0031] In some embodiments, in order to avoid affecting the charge and discharge performance of the solid-state battery, the thickness of the insulating film is 5 μm - 30 μm.

[0032] The insulating film of the solid-state battery provided by the present application, by introducing specific thermosensitive groups into polyallyl carbonate, on the one hand, enables the insulating film to retain the excellent electronic insulating properties of polyallyl carbonate, and on the other hand, the thermosensitive groups introduced into the modified polyallyl carbonate can make the insulating film exhibit the characteristic of poor thermal stability and be easily decomposed at 120°C - 150°C. In particular, by selecting specific thermosensitive groups in the embodiments of the present application, there are no moisture and other solid residues after the insulating film is decomposed by heat. When the above insulating film is applied to a solid-state battery, especially in the high-potential test field of a solid-state battery, it can improve the intrinsic breakdown voltage of the solid-state battery, effectively avoid the risk of the solid-state battery being broken down, and facilitate the removal of the insulating film after testing, which is beneficial to improving the charge and discharge performance of the solid-state battery.

[0033] In some examples, the insulating film for a solid-state battery described above can be prepared by the following preparation method.

[0034] Step 1: Prepare modified polyallyl carbonate.

[0035] Among them, the modified polyallyl carbonate includes a thermosensitive group, and the thermosensitive group is selected from at least one of tert-butoxycarbonyl, azodicarboxylate, sulfonyl azide, tert-butyl carbonate, and nitro. The doping amount of the thermosensitive group makes the thermal decomposition temperature of the modified polyallyl carbonate be 120°C - 150°C. For example, it can be 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, 132°C, 134°C, 136°C, 138°C, 140°C, 142°C, 144°C, 146°C, 148°C, 150°C, etc., or other values within the above range.

[0036] Step 2: Prepare an insulating film from the modified polyallyl carbonate through a film-forming process.

[0037] In some embodiments, the film-forming process, for example, includes a casting process. The method of preparing an insulating film from the modified polyallyl carbonate through the film-forming process, for example, includes: preparing an insulating film from the modified polyallyl carbonate through the casting process.

[0038] It should be noted that the method for preparing the insulating film provided in the above embodiments belongs to the same concept as the embodiments of the insulating film for a solid-state battery. For a detailed description of the insulating film, reference can be made to the embodiments of the insulating film for a solid-state battery, and the same content will not be repeated here.

[0039] This application also provides a solid-state battery. The solid-state battery includes a positive electrode sheet, a negative electrode sheet, a solid electrolyte, and the insulating film as above. The insulating film is located between at least one of the positive electrode sheet and the negative electrode sheet and the solid electrolyte.

[0040] Optionally, the insulating film can be located between the positive electrode sheet and the solid electrolyte, so that the insulating film can form an insulating layer between the positive electrode sheet and the solid electrolyte of the solid-state battery to block the electron conduction path inside the solid-state battery; or the insulating film can be located between the negative electrode sheet and the solid electrolyte, so that the insulating film can form an insulating layer between the negative electrode sheet and the solid electrolyte of the solid-state battery to block the electron conduction path inside the solid-state battery.

[0041] In some embodiments, the solid-state battery provided in the embodiments of this application also includes a positive current collector disposed on the side of the positive electrode sheet away from the solid electrolyte, and a negative current collector disposed on the side of the negative electrode sheet away from the solid electrolyte.

[0042] Figure 1 is a schematic structural diagram of the solid-state battery provided in the embodiments of this application. Refer to Figure 1 , the solid-state battery provided in the embodiments of this application includes, for example, a positive current collector 110, a positive electrode sheet 120, an insulating film 130, a solid electrolyte 140, a negative electrode sheet 150, and a negative current collector 160 stacked in sequence.

[0043] Among them, the positive current collector 110 can be used for but not limited to collecting the current generated by the positive electrode sheet and conducting it to the external circuit. The positive current collector can include, for example, aluminum foil. The positive electrode sheet 120 can be used for but not limited to storing or releasing electrical energy by inserting and extracting metal ions (such as lithium ions or other metal ions). The insulating film 130 is disposed between the positive electrode sheet 120 and the solid electrolyte 140 and can be used for but not limited to improving the insulation performance of the solid-state battery. The solid electrolyte 140 can be used for but not limited to conducting metal ions (such as lithium ions or other metal ions). The negative electrode sheet 150 can be used for but not limited to storing or releasing electrical energy by inserting and extracting metal ions (such as lithium ions or other metal ions).

[0044] Figure 2 is a schematic structural diagram of another solid-state battery provided by an embodiment of the present application. Refer to Figure 2 , another solid-state battery provided by an embodiment of the present application includes, for example, a positive current collector 210, a positive electrode sheet 220, a solid electrolyte 230, an insulating film 240, a negative electrode sheet 250, and a negative current collector 260 stacked in sequence.

[0045] It should be noted that Figure 2 the difference between the solid-state battery shown in Figure 1 and the solid-state battery shown in

[0046] is that the insulating film 240 is disposed between the negative electrode sheet 250 and the solid electrolyte 230, and the same content will not be repeated here.

[0047] The present application also provides a method for testing the insulation performance of a solid-state battery, and the method includes the following steps.

[0048] Step 1: Test the solid-state battery through a high-potential test process, where the solid-state battery uses the solid-state battery as described above.

[0049] Step 2: Keep the tested solid-state battery warm at 120°C - 150°C.

[0050] In some embodiments, the duration of the heat preservation treatment is 30 min - 60 min.

[0051] In the solid-state battery insulation performance testing method provided by the embodiments of the present application, the solid-state battery used includes an insulating film. By introducing specific thermosensitive groups into the insulating film, on the one hand, the solid-state battery has a relatively high intrinsic breakdown voltage, which is beneficial to improving the reliability of the test results when testing the internal short-circuit condition of the solid-state battery through high-potential testing. On the other hand, after the high-potential testing is completed, the insulating film can be removed by subjecting the solid-state battery to heat preservation treatment at 120°C - 150°C, which is beneficial to improving the charge-discharge performance of the solid-state battery.

[0052] The exemplary embodiments of the present invention will be described in more detail below. Although the exemplary embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. For those where specific techniques or conditions are not indicated in the examples, they shall be carried out according to the techniques or conditions described in the literature in the art or according to the product specifications. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0053] Example 1

[0054] Example 1 provides a method for preparing an insulating film, which includes the following steps:

[0055] Step 1: Prepare modified poly(allyl carbonate) with tert-butoxycarbonyl groups introduced, which includes:

[0056] Dissolve 10.0 g of poly(allyl carbonate) (0.8 mmol repeating unit) in 150 ml of anhydrous dichloromethane, then add 18.5 g of tert-butoxycarbonyl anhydride (85 mmol) and 0.5 g of 4-dimethylaminopyridine, and then stir and react for 24 h under a nitrogen atmosphere and at 55°C. Then add cold methanol to the product, and after vacuum drying the obtained precipitate, a white powder is obtained, which is tert-butoxycarbonyl-modified poly(allyl carbonate).

[0057] Step 2: Prepare an insulating film from the tert-butoxycarbonyl-modified poly(allyl carbonate) through a casting process, which includes: uniformly casting the tert-butoxycarbonyl-modified poly(allyl carbonate) onto a substrate through a casting machine to form a uniform wet film, and obtaining an insulating film after the wet film is dried. Among them, the thickness of the insulating film is 10 μm.

[0058] The resistance of the insulating film prepared in Example 1 was measured using AC impedance spectroscopy. The measurement steps included: clamping the insulating film between two stainless steel sheets to assemble a button cell, and then using an electrochemical workstation to measure the impedance response of the insulating film in the frequency range of 0.1 Hz to 1 MHz. The electronic impedance of the insulating film was obtained by fitting with a series resistance model. The test results are shown in Table 1.

[0059] Example 2

[0060] Example 2 provides a method for preparing an insulating film, which includes the following steps:

[0061] Step 1: Prepare a modified polyallyl carbonate incorporating azodicarboxylate, which includes:

[0062] Under light-shielded conditions, 10.0 g of polyallyl carbonate (0.8 mmol repeating unit) and 12.3 g of azodicarbonyl chloride (75 mmol) were dissolved in 120 ml of anhydrous THF (Tetrahydrofuran), then 15 ml of triethylamine was added, and then the reaction was carried out at 0 °C for 6 h, and then the temperature was raised to 25 °C and the reaction was continued for 12 h. Ether / water extraction was performed on the product, and the obtained orange solid was purified to obtain azodicarboxylate-modified polyallyl carbonate.

[0063] Step 2: Prepare an insulating film from the azodicarboxylate-modified polyallyl carbonate by a casting process, which includes:

[0064] The tert-butoxycarbonyl-modified polyallyl carbonate was evenly cast onto a substrate by a casting machine to form a uniform wet film, and the insulating film was obtained after the wet film was dried. Among them, the thickness of the insulating film was 10 μm.

[0065] The resistance of the insulating film prepared in Example 2 was measured using AC impedance spectroscopy. The measurement steps included: clamping the insulating film between two stainless steel sheets to assemble a button cell, and then using an electrochemical workstation to measure the impedance response of the insulating film in the frequency range of 0.1 Hz to 1 MHz. The electronic impedance of the insulating film was obtained by fitting with a series resistance model. The test results are shown in Table 1.

[0066] Example 3

[0067] Example 3 provides a method for preparing an insulating film, which includes the following steps:

[0068] Step 1: Prepare a modified polyallyl carbonate incorporating sulfonyl azide, which includes:

[0069] At 80 °C, 10.0 g of poly(allyl carbonate) (0.8 mmol repeating units) was reacted with 9.5 g of sulfonyl chloride (70 mmol) in toluene for 5 h to form a sulfonyl chloride intermediate. Then, after cooling to 0 °C, a solution of sodium azide in DMF (Dimethylformamide, N,N-dimethylformamide) (the mass of sodium azide in the solution was 6.8 g, and the molar amount was 105 mmol) was added. Then, it was stirred at room temperature for 8 h. After dialysis purification, a pale yellow product was obtained, which was poly(allyl carbonate) modified with sulfonyl azide.

[0070] Step 2: Prepare an insulating film from the poly(allyl carbonate) modified with sulfonyl azide by a casting process, which includes:

[0071] The poly(allyl carbonate) modified with tert-butoxycarbonyl was evenly cast onto a substrate by a casting machine to form a uniform wet film. After the wet film was dried, an insulating film was obtained. Among them, the thickness of the insulating film was 10 μm.

[0072] The resistance of the insulating film prepared in Example 3 was tested using an alternating current impedance spectroscopy method. The test steps included: sandwiching the insulating film between two stainless steel sheets to assemble a button cell, and then using an electrochemical workstation to test the impedance response of the insulating film in the frequency range of 0.1 Hz to 1 MHz. The electronic impedance of the insulating film was obtained by fitting with a series resistance model. The test results are shown in Table 1.

[0073] Example 4

[0074] Example 4 provides a method for preparing an insulating film, which includes the following steps:

[0075] Step 1: Prepare a modified poly(allyl carbonate) incorporating tert-butyl carbonate, which includes:

[0076] 10.0 g of poly(allyl carbonate) (0.8 mmol repeating units) 、 13.2 g of tert-butyl chloroformate (90 mmol) and 7.1 ml of pyridine were dissolved in 120 ml of toluene solution and reacted at 45 °C for 36 h. Then, n-hexane was added to the reaction product to obtain a transparent elastomer, which was poly(allyl carbonate) modified with tert-butyl carbonate.

[0077] Step 2: Prepare an insulating film from the modified poly(allyl carbonate) incorporating tert-butyl carbonate by a casting process, which includes:

[0078] The poly(allyl carbonate) modified with tert-butoxycarbonyl was evenly cast onto a substrate by a casting machine to form a uniform wet film. After the wet film was dried, an insulating film was obtained. Among them, the thickness of the insulating film was 10 μm.

[0079] The resistance of the insulating film prepared in Example 4 was tested using the alternating current impedance spectroscopy method. The test steps included: clamping the insulating film between two stainless steel sheets to assemble a button cell, and then using an electrochemical workstation to test the impedance response of the insulating film in the frequency range of 0.1 Hz to 1 MHz. The electronic impedance of the insulating film was obtained by fitting with a series resistance model. The test results are shown in Table 1.

[0080] Table 1

[0081] Example Electrical impedance (Ω / cm) Example 1 <![CDATA[1.2×10 15 > Example 2 <![CDATA[1.6×10 15 > Example 3 <![CDATA[1.1×10 15 > Example 4 <![CDATA[2.6×10 15 >

[0082] As can be seen from Table 1, the insulating films provided in the embodiments of the present application all have relatively high electronic impedance and good electronic insulation performance, which can greatly improve the insulation performance inside the solid-state battery, effectively block the electronic conduction path inside the solid-state battery, and keep the inside of the solid-state battery in an open circuit state.

[0083] When this insulating film is applied to a solid-state battery, it can effectively avoid the risk of internal breakdown of the solid-state battery when testing the internal short-circuit condition of the solid-state battery through a high-potential test process, which is beneficial to improving the insulation performance inside the solid-state battery and ensuring the quality of the battery. In particular, the insulating film can decompose into gas at 120°C - 150°C, which is beneficial to removing the insulating film in the solid-state battery after the test is completed and ensuring the charge and discharge performance of the solid-state battery.

[0084] The above description is only for the convenience of those skilled in the art to understand the technical solution of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. An insulating film for a solid-state battery, characterized in that, The insulating film includes modified polyallyl carbonate, the modified polyallyl carbonate includes a thermosensitive group, the thermosensitive group is selected from at least one of tert-butoxycarbonyl, azodicarboxylate, sulfonyl azide, tert-butyl carbonate and nitro, and the doping amount of the thermosensitive group makes the thermal decomposition temperature of the modified polyallyl carbonate be 120°C - 150°C.

2. The insulating film according to claim 1, characterized in that, The doping percentage of the thermosensitive group in the modified polyallyl carbonate is 10% - 30%.

3. The insulating film according to claim 1, characterized in that, The electronic impedance of the insulating film is greater than 1.0×10 15 Ω / cm.

4. The insulating film according to claim 1, characterized in that, The thickness of the insulating film is 5μm - 30μm.

5. A method for preparing an insulating film, characterized in that, The method includes: Preparing modified polyallyl carbonate, the modified polyallyl carbonate includes a thermosensitive group, the thermosensitive group is selected from at least one of tert-butoxycarbonyl, azodicarboxylate, sulfonyl azide, tert-butyl carbonate and nitro, and the doping amount of the thermosensitive group makes the thermal decomposition temperature of the modified polyallyl carbonate be 120°C - 150°C; Preparing the insulating film from the modified polyallyl carbonate through a film-forming process.

6. A solid-state battery, characterized in that, The solid-state battery includes a positive electrode sheet, a negative electrode sheet, a solid electrolyte, and the insulating film according to any one of claims 1 - 4; The insulating film is located between at least one of the positive electrode sheet and the negative electrode sheet and the solid electrolyte.

7. The solid-state battery according to claim 6, characterized in that, The insulating film is located between the positive electrode sheet and the solid electrolyte.

8. The solid-state battery according to claim 6, characterized in that, The insulating film is located between the negative electrode sheet and the solid electrolyte.

9. A method for testing the insulation performance of a solid-state battery, characterized in that, The method includes: Testing the solid-state battery through a high-potential testing process, wherein the solid-state battery uses the solid-state battery according to any one of claims 6 - 8; Performing a heat preservation treatment on the tested solid-state battery at 120°C - 150°C.

10. The method according to claim 9, wherein The duration of the heat preservation treatment is 30min - 60min.

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