Flame-retardant in-situ curing gel solid electrolyte with self-repairing function and preparation method thereof

Abstract

The present application relates to the technical field of lithium ion battery, in particular to a flame-retardant in-situ cured gel solid electrolyte with self-repairing function and a preparation method thereof. The gel solid electrolyte is formed in the assembling process of lithium ion battery by non-in-situ polymerization, and the interface resistance between the gel solid electrolyte and electrode active material is large, which can significantly reduce the conductivity of electrolyte. In view of the above technical problems, the present application provides a flame-retardant in-situ cured gel solid electrolyte with self-repairing function, which is a semi-solid gel product obtained by polymerization and crosslinking of flame-retardant in-situ cured gel solid electrolyte under heating condition. The flame-retardant in-situ cured gel solid electrolyte is obtained by in-situ polymerization of flame-retardant in-situ cured gel solid electrolyte in lithium ion battery, and the interface resistance between the gel solid electrolyte and electrode active material is small, the conductivity of the obtained electrolyte is high, and the conductivity and capacity retention rate of lithium ion battery are further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a flame-retardant in-situ curing gel solid electrolyte with self-repairing function and a preparation method thereof. BACKGROUND

[0002] Lithium ion batteries have long cycle life and high energy density, and are widely used in mobile electronic devices and large energy storage devices. However, the traditional liquid electrolyte is difficult to meet the demand of further development of lithium ion batteries in the direction of safety and high energy density. In contrast, the unique semi-solid nature of gel solid electrolyte can avoid leakage of organic liquid and inhibit the growth of lithium dendrites, thereby improving the safety performance of the battery.

[0003] The non-in-situ polymerization of gel solid electrolyte usually prepares a gel solid electrolyte matrix externally, and then drips the electrolyte into it to soak in during the battery assembly process, so as to form the gel solid electrolyte. However, this method is difficult to achieve close contact between the gel matrix and the surface of the active material, and the interface resistance between the electrolyte and the electrode active material is large, which will significantly reduce the overall electrical performance of the lithium ion battery, such as the obvious decline of the specific capacity of the battery and the electrolyte conductivity. SUMMARY

[0004] The existing problem is that the gel solid electrolyte is formed in the lithium ion battery assembly process by using the non-in-situ polymerization method, and the interface resistance between the gel solid electrolyte and the electrode active material is large, which will significantly reduce the electrolyte conductivity. In view of the above technical problems, the present application provides a flame-retardant in-situ curing gel solid electrolyte with self-repairing function, which is a semi-solid gel product obtained by polymerization and crosslinking of a flame-retardant in-situ curing gel solid electrolyte under heating conditions. The flame-retardant in-situ curing gel solid electrolyte comprises a lithium salt, a non-aqueous organic solvent, a gel polymerization monomer and an initiator, the gel polymerization monomer is composed of a flame-retardant monomer, a crosslinking monomer and a self-repairing monomer according to a molar ratio of 0.1-2:1:0.1-2, the flame-retardant monomer structure has a P-F chemical bond and a cyclotriphosphazene group, and the self-repairing monomer structure has a Si-O-Si chemical bond.

[0005] Preferably, the non-aqueous organic solvent comprises one or more of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), fluoroethylene carbonate (FEC), gamma-butyrolactone (BC), methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP) and propyl propionate (PP).

[0006] Preferably, the lithium salt comprises one or several of lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium bis(oxalato)borate (LiBOB), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0007] Preferably, the flame retardant monomer comprises one or several of 2,4- bis(butenyloxy)tetrafluorocyclotriphosphazene, 2,4,6-tris(butenyloxy)trifluorocyclotriphosphazene, 3-propenyloxy-pentafluorocyclotriphosphazene, 2,4- bis(propenyloxy)tetrafluorocyclotriphosphazene, 2,4,6-tris(propenyloxy)trifluorocyclotriphosphazene, 3-vinyloxy-pentafluorocyclotriphosphazene, 2,4- bis(vinyloxy)tetrafluorocyclotriphosphazene, 3-butenyloxy-pentafluorocyclotriphosphazene.

[0008] wherein the structure of 3-butenyloxy-pentafluorocyclotriphosphazene is as follows:

[0009]

[0010] The structure of 2,4-bis(butenyloxy)tetrafluorocyclotriphosphazene is as follows:

[0011]

[0012] The structure of 2,4,6-tris(butenyloxy)trifluorocyclotriphosphazene is as follows:

[0013]

[0014] The structure of 3-propenyloxy-pentafluorocyclotriphosphazene is as follows:

[0015]

[0016] The structure of 2,4-bis(propenyloxy)tetrafluorocyclotriphosphazene is as follows:

[0017]

[0018] The structure of 2,4,6-tris(propenyloxy)trifluorocyclotriphosphazene is as follows:

[0019] The structure of 3-vinyloxy-pentafluorocyclotriphosphazene is as follows:

[0020] The structure of 2,4-bis(vinyloxy)tetrafluorocyclotriphosphazene is as follows:

[0021]

[0022] The structure of 2,4,6-tris(vinyloxy)trifluorocyclotriphosphazene is as follows:

[0023]

[0024] Preferably, the crosslinking monomer comprises N,N'-methylenebisacrylamide.

[0025] Preferably, the self-repairing monomer comprises one or more of tetramethyldivinyl disiloxane, vinyl-terminated dimethyl polysiloxane, tris(vinyldimethylsiloxy)phenylsilane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane.

[0026] Preferably, the initiator comprises one or more of azobisisobutyronitrile, benzoyl peroxide, azobisisoheptane, dimethyl azobis isobutyrate.

[0027] Preferably, the concentration of lithium salt in the base electrolyte is 0.5-2 mol / L.

[0028] Preferably, the amount of initiator added accounts for 0.1-0.2% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte.

[0029] Preferably, the amount of gel polymerization monomer added accounts for 1-25% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte. The present application has the following beneficial effects:

[0030] (1) The present application forms a flame-retardant in-situ cured gel solid-state electrolyte during the assembly of a lithium ion battery by in-situ polymerization, the interface resistance between the gel solid-state electrolyte and the electrode active material is small, which does not reduce the electrolyte conductivity, and is conducive to improving the conductivity and capacity retention rate of the lithium ion battery;

[0031] (2) The present application finds that the composition of the polymerization monomer has a significant influence on the conductivity of the obtained flame-retardant in-situ cured gel solid-state electrolyte, and the conductivity of the obtained flame-retardant in-situ cured gel solid-state electrolyte is significantly different due to the composition of different polymerization monomers, which further affects the performance of the lithium ion battery;

[0032] (3) The flame-retardant in-situ cured gel solid-state electrolyte obtained by the present application uses polymerization monomers with flame retardance in the preparation process, which can further improve the use safety of the lithium ion battery;

[0033] (4) The flame-retardant in-situ cured gel solid-state electrolyte obtained by the present application has Si-O-Si chemical bonds, and the unique dynamic balance of the Si-O-Si chemical bonds endows the gel solid-state electrolyte with good self-repairing ability, which can well inhibit the growth of lithium dendrites. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1: Optical photos of the flame-retardant in-situ cured gel solid electrolyte obtained in Example 1-3 and the flame-retardant in-situ cured gel solid electrolyte obtained after heating and curing.

[0035] Figure 2 : Flame-retardant performance test results of the flame-retardant in-situ cured gel solid electrolyte obtained in Example 1.

[0036] Figure 3 : Conductivity test results of the flame-retardant in-situ cured gel solid electrolyte obtained in Example 1-3. DETAILED DESCRIPTION

[0037] The application will be described in detail below in conjunction with the examples. However, it should be understood that the following examples are only illustrative of the embodiments of the application, and are not a limitation on the scope of the application.

[0038] The main manufacturing process parameters of the CR2032 button cell to be injected in the application are as follows:

[0039] The positive plate of the CR2032 button cell is mixed with positive active material (lithium nickel cobalt manganese ternary positive NCM811-S800, purchased from Ningbo Rongbai New Energy Technology Co., Ltd.), conductive carbon black (Ketjen black EC-300J, Japan Lion), and polyvinylidene fluoride PVDF (France Arkema) in a mass ratio of 96:2:2, then an appropriate amount of N-methyl pyrrolidone (NMP) is added to obtain a positive slurry with a solid content of 65%, then the positive slurry is uniformly coated on both sides of an aluminum foil with a double-sided coating density of 28 mg / cm 2 , a compacted density of 3.4 g / cm 3 , a double-sided coating thickness of 97 μm, and an aluminum foil thickness of 15 μm, and the positive plate is cut into a 14 mm round piece.

[0040] The negative electrode of the CR2032 button cell is lithium metal (Tianjin Zhongneng Lithium Industry Co., Ltd., 16 mm diameter lithium metal round piece, 0.1 mm thick).

[0041] The separator of the CR2032 button cell is Celgard 2325, 25 μm, purchased from Celgard Company, USA.

[0042] The test method of the conductivity in the application is as follows:

[0043] The ion conductivity is measured by electrochemical impedance spectroscopy (EIS) using a Swiss Autolab electrochemical workstation. A potential of ±10 mV is applied to a stainless steel (SS) symmetric cell with a frequency range of 0.1 Hz to 1 MHz. The ion conductivity can be calculated by the following formula:

[0044]

[0045] wherein: I is the film thickness, Rb is the bulk resistance, and A is the area.

[0046] Example 1

[0047] A preparation method of the flame-retardant in-situ cured gel solid electrolyte is as follows:

[0048] (1) 1 mol of LiPF6 is added to a non-aqueous organic solvent to obtain a base electrolyte, the non-aqueous organic solvent is composed of DEC, EC and EMC in a volume ratio of 2:3:5, and the concentration of LiPF6 in the base electrolyte is 1 mol / L;

[0049] (2) Then, gel polymer monomers and azobisisobutyronitrile are added to the base electrolyte and stirred to disperse uniformly, thereby obtaining the flame-retardant in-situ cured gel solid electrolyte, the gel polymer monomers are composed of 3-butenyloxy pentafluorocyclotriphosphazene (Suzhou Yakete Science and Technology Co., Ltd., product number D0519), N,N'-methylenebisacrylamide and tetramethyldivinyl disiloxane in a molar ratio of 1:1:1, the total weight of the gel polymer monomers accounts for 3% of the total mass of the flame-retardant in-situ cured gel solid electrolyte, the addition amount of the azobisisobutyronitrile accounts for 0.5% of the total mass of the flame-retardant in-situ cured gel solid electrolyte, and the base electrolyte accounts for 96.5% of the total mass of the flame-retardant in-situ cured gel solid electrolyte.

[0050] Example 2 is the same as Example 1, except that in Example 2, the total weight of the gel polymer monomers accounts for 7% of the total mass of the flame-retardant in-situ cured gel solid electrolyte.

[0051] Example 3 is the same as Example 1, except that in Example 3, the total weight of the gel polymer monomers accounts for 10% of the total mass of the flame-retardant in-situ cured gel solid electrolyte.

[0052] The optical photographs of the flame-retardant in-situ cured gel solid electrolytes obtained in Examples 1-3 and the morphologies of the flame-retardant in-situ cured gel solid electrolytes obtained after heat curing are shown in the accompanying drawings of the specification. Figure 1 The conductivity of the flame-retardant in-situ cured gel solid electrolytes formed by curing the flame-retardant in-situ cured gel solid electrolytes obtained in Examples 1-3 is tested, and the specific test results are shown in the accompanying drawings of the specification. Figure 3 With the increase of the proportion of the gel polymer monomers in the flame-retardant in-situ cured gel solid electrolyte, the conductivity decreases from 0.556 mS / cm to 0.24 mS / cm. The flame-retardant performance of the flame-retardant in-situ cured gel solid electrolyte obtained in Example 1 is shown in the accompanying drawings of the specification. Figure 2

[0053] Example 4

[0054] ​A preparation method of the flame-retardant in-situ cured gel solid-state electrolyte is as follows:

[0055] (1) 1.1 mol of LiPF6 is added into a non-aqueous organic solvent to obtain a base electrolyte, the non-aqueous organic solvent is composed of EC and EMC in a volume ratio of 3:7, and the concentration of LiPF6 in the base electrolyte is 1.1 mol / L;

[0056] (2) Then, gel polymer monomers and azobisisobutyronitrile are added into the base electrolyte and stirred and dispersed uniformly to obtain the flame-retardant in-situ cured gel solid-state electrolyte, the gel polymer monomers are composed of 3-butenyloxy pentafluorocyclotriphosphazene (Suzhou Yakete Science and Technology Co., Ltd., D0519), N,N'-methylene bisacrylamide, and vinyl-terminated dimethyl polysiloxane (CAS: 68083-19-2) in a molar ratio of 1.1:1:0.5, the total weight of the gel polymer monomers accounts for 8% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte, the addition amount of the azobisisobutyronitrile accounts for 0.6% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte, and the base electrolyte accounts for 91.4% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte.

[0057] Example 5

[0058] A preparation method of the flame-retardant in-situ cured gel solid-state electrolyte is as follows:

[0059] (1) 1.2 mol of LiPF6 is added into a non-aqueous organic solvent to obtain a base electrolyte, the non-aqueous organic solvent is composed of PC, EC, and EMC in a volume ratio of 2:3:5, and the concentration of LiPF6 in the base electrolyte is 1.2 mol / L;

[0060] (2) Then, gel polymer monomers and azobisisobutyronitrile are added into the base electrolyte and stirred and dispersed uniformly to obtain the flame-retardant in-situ cured gel solid-state electrolyte, the gel polymer monomers are composed of 3-butenyloxy pentafluorocyclotriphosphazene, N,N'-methylene bisacrylamide, and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane in a molar ratio of 0.5:1:0.4, the total weight of the gel polymer monomers accounts for 10% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte, the addition amount of the azobisisobutyronitrile accounts for 0.7% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte, and the base electrolyte accounts for 89.3% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte.

[0061] Example 6

[0062] A preparation method of the flame-retardant in-situ cured gel solid-state electrolyte is as follows:

[0063] (1) 1 mol LiPF6 was added to a non-aqueous organic solvent to obtain a base electrolyte, the non-aqueous organic solvent was composed of EC and DMC in a volume ratio of 2:8, the concentration of LiPF6 in the base electrolyte was 1 mol / L;

[0064] (2) Then, a gel polymerization monomer and azobisisobutyronitrile were added to the base electrolyte and stirred to disperse uniformly, thereby obtaining a flame-retardant in-situ cured gel solid-state electrolyte, the gel polymerization monomer was composed of 3-butenyloxy pentafluorocyclotriphosphazene (Suzhou Yakete Science and Technology Co., Ltd., D0519), N,N'-methylene bisacrylamide, and tris (vinyl dimethylsiloxy) phenylsilane in a molar ratio of 0.6:1:0.5, the total weight of the gel polymerization monomer accounted for 4% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte, the addition amount of the azobisisobutyronitrile accounted for 0.4% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte, and the base electrolyte accounted for 95.6% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte.

[0065] Example 7

[0066] A preparation method of a flame-retardant in-situ cured gel solid-state electrolyte is as follows:

[0067] (1) 1.1 mol LiPF6 was added to a non-aqueous organic solvent to obtain a base electrolyte, the non-aqueous organic solvent was composed of EC and DEC in a volume ratio of 4:6, the concentration of LiPF6 in the base electrolyte was 1.1 mol / L;

[0068] (2) Then, a gel polymerization monomer and azobisisobutyronitrile were added to the base electrolyte and stirred to disperse uniformly, thereby obtaining a flame-retardant in-situ cured gel solid-state electrolyte, the gel polymerization monomer was composed of 3-butenyloxy pentafluorocyclotriphosphazene, N,N'-methylene bisacrylamide, and tris (vinyl dimethylsiloxy) phenylsilane in a molar ratio of 0.6:1:0.9, the total weight of the gel polymerization monomer accounted for 4% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte, the addition amount of the azobisisobutyronitrile accounted for 0.4% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte, and the base electrolyte accounted for 95.6% of the total mass of the flame-retardant in-situ cured gel solid-state electrolyte.

[0069] Example 8

[0070] A preparation method of a flame-retardant in-situ cured gel solid-state electrolyte is as follows:

[0071] (1) 1.2 mol LiPF6 was added to a non-aqueous organic solvent to obtain a base electrolyte, the non-aqueous organic solvent was composed of EC, DEC, and FEC in a volume ratio of 3:3:4, the concentration of LiPF6 in the base electrolyte was 1.2 mol / L;

[0072] (2) then adding gel polymerization monomers and azobisisobutyronitrile in the base electrolyte, stirring and dispersing uniformly, thus obtaining the flame-retardant in-situ cured gel solid electrolyte, wherein the gel polymerization monomers are composed of 3-butenyloxy pentafluorocyclotriphosphazene, N,N'-methylene bisacrylamide and tris(vinyldimethylsiloxy)phenylsilane in a molar ratio of 0.5:1:0.7, the total weight of the gel polymerization monomers accounts for 8% of the total mass of the flame-retardant in-situ cured gel solid electrolyte, the addition amount of the azobisisobutyronitrile accounts for 0.8% of the total mass of the flame-retardant in-situ cured gel solid electrolyte, and the base electrolyte accounts for 91.2% of the total mass of the flame-retardant in-situ cured gel solid electrolyte.

[0073] Comparative Example 1 is the same as Example 4, except that in Comparative Example 1, the gel polymerization monomers are composed of 3-butenyloxy pentafluorocyclotriphosphazene, N,N'-methylene bisacrylamide and vinyl-terminated dimethyl polysiloxane in a molar ratio of 0.05:1:0.5.

[0074] Comparative Example 2 is the same as Example 4, except that in Comparative Example 2, the gel polymerization monomers are composed of 3-butenyloxy pentafluorocyclotriphosphazene, N,N'-methylene bisacrylamide and vinyl-terminated dimethyl polysiloxane in a molar ratio of 1.1:1:0.

[0075] Comparative Example 3 is the same as Example 4, except that in Comparative Example 3, the gel polymerization monomers are composed of 3-butenyloxy pentafluorocyclotriphosphazene, N,N'-methylene bisacrylamide and vinyl-terminated dimethyl polysiloxane in a molar ratio of 3:1:1.

[0076] Comparative Example 4 is the same as Example 4, except that in Comparative Example 4, the gel polymerization monomers are composed of 3-butenyloxy pentafluorocyclotriphosphazene, N,N'-methylene bisacrylamide and vinyl-terminated dimethyl polysiloxane in a molar ratio of 1.1:1:3.

[0077] Comparative Example 5 is the same as Example 4, except that in Comparative Example 5, the total weight of the gel polymerization monomers accounts for 30% of the total mass of the flame-retardant in-situ cured gel solid electrolyte.

[0078] Performance Test

[0079] The optical photographs of the flame-retardant in-situ cured gel solid electrolytes and electrolytes obtained in Examples 1-3 are shown in the accompanying drawings of the specification. Figure 1

[0080] The combustion situation of the flame-retardant in-situ cured gel solid electrolyte obtained in Example 1 after ignition is shown in the accompanying drawings of the specification. Figure 2

[0081] ​​The flame-retardant in-situ cured gel solid electrolyte obtained in Example 1-3 was injected into the steel shell of a CR2032 button cell to be injected with electrolyte, and the electrolyte was cured in situ in the steel shell by heating (60°C) to form a flame-retardant in-situ cured gel solid electrolyte. After subsequent packaging of the battery, three different button cells were obtained.

[0082] Under the same test conditions, the impedance of the button cells obtained in Examples 1-3 was tested, and the test results are shown in FIG. 2. Figure 3 As shown in FIG. 2, the test results show that as the proportion of gel polymer monomers in the flame-retardant in-situ cured gel solid electrolyte increases, the impedance of the button cell tends to increase.

[0083] The flame-retardant in-situ cured gel solid electrolyte obtained in Example 4 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid electrolyte. The conductivity of the flame-retardant in-situ cured gel solid electrolyte obtained in Example 4 was tested to be 1.03 mS / cm.

[0084] The flame-retardant in-situ cured gel solid electrolyte obtained in Example 4 was injected into the steel shell of a CR2032 button cell to be injected with electrolyte (the injection coefficient was 5 g / Ah), and the electrolyte was cured in situ in the steel shell by heating (60°C) to form a flame-retardant in-situ cured gel solid electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 214 mAh / g. The button cell obtained in Example 4 was subjected to a charge-discharge (1C charge, 1C discharge) cycle life test in the voltage range of 2.7-4.4V. The capacity retention rate of the button cell obtained in Example 4 after 100 charge-discharge cycle tests could still reach 91%.

[0085] The flame-retardant in-situ cured gel solid electrolyte obtained in Example 5 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid electrolyte. The conductivity of the flame-retardant in-situ cured gel solid electrolyte obtained in Example 5 was tested to be 0.42 mS / cm.

[0086] The flame-retardant in-situ cured gel solid electrolyte obtained in Example 5 was injected into the steel shell of a CR2032 button cell to be injected with electrolyte (the injection coefficient was 5 g / Ah), and the electrolyte was cured in situ in the steel shell by heating (60°C) to form a flame-retardant in-situ cured gel solid electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 202 mAh / g. The button cell obtained in Example 5 was subjected to a charge-discharge (1C charge, 1C discharge) cycle life test in the voltage range of 2.7-4.4V. The test results show that the capacity retention rate of the button cell obtained in Example 5 after 100 charge-discharge cycle tests could still reach 92%.

[0087] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Example 6 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. The conductivity of the flame-retardant in-situ cured gel solid-state electrolyte obtained in Example 6 was 0.39 mS / cm.

[0088] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Example 6 was injected into the steel shell of a CR2032 button cell to be injected (the injection coefficient was 5 g / Ah), and the electrolyte was cured in-situ by heating (60°C) in the steel shell to form a flame-retardant in-situ cured gel solid-state electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 197 mAh / g. The button cell obtained in Example 6 was subjected to a charge-discharge (1C charge, 1C discharge) cycle life test in the voltage range of 2.7-4.4V. The test results showed that the capacity retention rate of the button cell obtained in Example 6 after 100 charge-discharge cycle tests could still reach 95%.

[0089] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Example 7 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. The conductivity of the flame-retardant in-situ cured gel solid-state electrolyte obtained in Example 7 was 0.48 mS / cm.

[0090] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Example 7 was injected into the steel shell of a CR2032 button cell to be injected (the injection coefficient was 5 g / Ah), and the electrolyte was cured in-situ by heating (60°C) in the steel shell to form a flame-retardant in-situ cured gel solid-state electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 203 mAh / g. The button cell obtained in Example 7 was subjected to a charge-discharge (1C charge, 1C discharge) cycle life test in the voltage range of 2.7-4.4V. The test results showed that the capacity retention rate of the button cell obtained in Example 7 after 100 charge-discharge cycle tests could still reach 88.4%.

[0091] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Example 8 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. The conductivity of the flame-retardant in-situ cured gel solid-state electrolyte obtained in Example 8 was 0.40 mS / cm.

[0092] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Example 8 was injected into the steel shell of a CR2032 button cell to be injected (the injection coefficient was 5 g / Ah), and the electrolyte was cured in-situ in the steel shell (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 199 mAh / g. The button cell obtained in Example 8 was subjected to a charge-discharge cycle life test (1C charge, 1C discharge) in the voltage range of 2.7-4.4V. The test results showed that the capacity retention rate of the button cell obtained in Example 8 after 100 charge-discharge cycle tests could still reach 97.2%.

[0093] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 1 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. The conductivity of the flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 1 was 0.08 mS / cm.

[0094] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 1 was injected into the steel shell of a CR2032 button cell to be injected (the injection coefficient was 5 g / Ah), and the electrolyte was cured in-situ in the steel shell (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 138.4 mAh / g. The capacity retention rate of the button cell obtained in Comparative Example 1 after 100 charge-discharge cycle tests could still reach 79%.

[0095] In addition, due to the small amount of 3-butenyloxy pentafluorocyclotriphosphazene added in Comparative Example 1, the flame retardant test results showed that although a gel solid-state electrolyte was formed, it did not have flame retardant properties.

[0096] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 2 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. The conductivity of the flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 2 was 0.13 mS / cm.

[0097] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 2 was injected into the steel shell of a CR2032 button cell to be injected (the injection coefficient was 5 g / Ah), and the electrolyte was cured in-situ in the steel shell (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 155 mAh / g. The capacity retention rate of the button cell obtained in Comparative Example 2 after 100 charge-discharge cycle tests was only 77%.

[0098] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 3 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. The conductivity of the flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 3 was 0.032 mS / cm.

[0099] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 3 was injected into the steel shell of a CR2032 button cell to be injected (the injection coefficient was 5 g / Ah), and the electrolyte was cured in-situ by heating (60°C) in the steel shell to form a flame-retardant in-situ cured gel solid-state electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 98.4 mAh / g. The capacity retention rate of the button cell obtained in Comparative Example 3 after 100 charge-discharge cycle tests was only 62%.

[0100] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 4 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. The conductivity of the flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 4 was 0.12 mS / cm.

[0101] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 4 was injected into the steel shell of a CR2032 button cell to be injected (the injection coefficient was 5 g / Ah), and the electrolyte was cured in-situ by heating (60°C) in the steel shell to form a flame-retardant in-situ cured gel solid-state electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 112.8 mAh / g. The capacity retention rate of the button cell obtained in Comparative Example 4 after 100 charge-discharge cycle tests was only 58%.

[0102] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 5 was cured by heating (60°C) to form a flame-retardant in-situ cured gel solid-state electrolyte. The conductivity of the flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 5 was 0.078 mS / cm.

[0103] The flame-retardant in-situ cured gel solid-state electrolyte obtained in Comparative Example 5 was injected into the steel shell of a CR2032 button cell to be injected (the injection coefficient was 5 g / Ah), and the electrolyte was cured in-situ by heating (60°C) in the steel shell to form a flame-retardant in-situ cured gel solid-state electrolyte. After subsequent packaging of the battery, a button cell was obtained. The 0.1C discharge specific capacity of the obtained button cell was 102 mAh / g. The capacity retention rate of the button cell obtained in Comparative Example 5 after 100 charge-discharge cycle tests was only 68%.

[0104] With the above ideal embodiments according to the present application as the inspiration, through the above description, relevant staff can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A flame-retardant in-situ curing gel solid-state electrolyte with self-repairing function, characterized in that, The semi-solid gel product is obtained by polymerization and cross-linking of the flame-retardant in-situ curing gel solid-state electrolyte under heating, the flame-retardant in-situ curing gel solid-state electrolyte comprises a base electrolyte, a gel polymerization monomer and an initiator, the base electrolyte is formed by mixing a lithium salt with a non-aqueous organic solvent, the gel polymerization monomer is composed of a flame-retardant monomer, a cross-linking monomer and a self-repairing monomer according to a molar ratio of 0.1-2:1:0.1-2, the flame-retardant monomer has a P-F chemical bond and a cyclotriphosphazene group in the structure, and the self-repairing monomer has a Si-O-Si chemical bond in the structure; The flame-retardant monomer comprises one or more of 3-butenyloxy pentafluorocyclotriphosphazene, 2,4-bisbutenyloxy tetrafluorocyclotriphosphazene, 2,4,6-trisbutenyloxy trifluorocyclotriphosphazene, 3-propenyloxy pentafluorocyclotriphosphazene, 2,4-bispropenyloxy tetrafluorocyclotriphosphazene, 2,4,6-trispropenyloxy trifluorocyclotriphosphazene, 3-ethenyloxy pentafluorocyclotriphosphazene, 2,4-bisethenyloxy tetrafluorocyclotriphosphazene and 3-butenyloxy pentafluorocyclotriphosphazene; The cross-linking monomer comprises N,N'-methylenebisacrylamide; The self-repairing monomer comprises one or more of tetramethyldivinyl disiloxane, vinyl-terminated dimethyl polysiloxane, tris(vinyldimethylsiloxy)phenylsilane and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane; The addition amount of the gel polymerization monomer accounts for 1-25% of the total mass of the flame-retardant in-situ curing gel solid-state electrolyte.

2. The flame-retardant in-situ curing gel solid-state electrolyte with self-repairing function according to claim 1, characterized in that, The non-aqueous organic solvent comprises one or more of EC, PC, EC, DMC, DEC, EMC, FEC, BC, MA, EA, EP and PP.

3. The flame-retardant in-situ curing gel solid-state electrolyte with self-repairing function according to claim 1, characterized in that, The lithium salt comprises one or more of LiClO4, LiBF4, LiPF6, LiBOB, LiODFB, LiFSI and LiTFSI.

4. The flame-retardant in-situ curing gel solid-state electrolyte with self-repairing function according to claim 1, characterized in that, The initiator comprises one or more of azobisisobutyronitrile, benzoyl peroxide, azobisisoheptyl nitrile and dimethyl azobis isobutyrate.

5. The flame-retardant in-situ curing gel solid-state electrolyte with self-repairing function according to claim 1, characterized in that, The concentration of the lithium salt in the base electrolyte is 0.5-2 mol / L.

6. The flame-retardant in-situ curing gel solid-state electrolyte with self-repairing function according to claim 1, characterized in that, The addition amount of the initiator accounts for 0.1-0.2% of the total mass of the flame-retardant in-situ curing gel solid-state electrolyte.

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