GEL ELECTROLYTE PRECURSOR AND USE THEREOF

Abstract

The present disclosure provides a gel electrolyte precursor and use thereof. The gel electrolyte precursor comprises a gel matrix monomer, a flexible additive, a polymerization initiator, and a lithium salt. The gel matrix monomer comprises an acrylonitrile-based monomer. The use of same in a semisolid battery achieves good electrical performance, and also reduces the amount of an electrolyte used. An acrylonitrile-based polymer obtained by the in-situ polymerization and gelation of an acrylonitrile-based monomer has good flame retardant performance and high voltage resistance, improving the safety performance of a battery.

Claims

1. A gel electrolyte precursor, comprising a gel skeleton monomer, a flexible additive, a polymerization initiator and a lithium salt, wherein the gel skeleton monomer comprises an acrylonitrile monomer.

2. The gel electrolyte precursor according to claim 1, wherein the acrylonitrile monomer comprises at least one of acrylonitrile, allyl nitrile, 2-bromoacrylonitrile, 1-cyclohexeneacetonitrile, 3,3-diphenylacrylonitrile, 3-cyclohexene-1-carbonitrile, 1-cyclopenteneacetonitrile, 2-ethoxyacrylonitrile, 1,2-dicyanocyclobutene, cyclovinyl-1,2-dinitrile, diaminomaleonitrile, 3,3-dimethoxy-2-acrylonitrile, ethoxymethylenemalononitrile, cis-2-(tert-Butyl)maleonitrile, 2,2,3,4,4-pentafluoro-3-butenenitrile, 1-cyano-2-propenyl acetate and benzylidenemalononitrile; preferably, the gel skeleton monomer is acrylonitrile.

3. (canceled)

4. The gel electrolyte precursor according to claim, wherein the flexible additive is selected from butanedinitrile and/or an ionic liquid; preferably the ionic liquid comprises at least one of 1-methyl-1-propylpiperidinium bis(trifluoromethylsulfonyl)imide salt, 1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide salt, 1-butyl-1-methylpyrrolidinium bis (trifluoromethanesulfonyl)imide salt, 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide salt, 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide sulfonimide salt and 1-ethyl-3-methyl imidazolium tetrafluoroborate salt.

5. (canceled)

6. The gel electrolyte precursor according to claim 1, wherein the polymerization initiator is selected from azobisisobutyronitrile and/or azobisisoheptanenitrile; preferably, the polymerization initiator is azobisisobutyronitrile.

7. (canceled)

8. The gel electrolyte precursor according to claim 1, wherein the lithium salt is selected from at least one of lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalato)borate and lithium tetrafluoroborate; preferably, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide.

9. (canceled)

10. The gel electrolyte precursor according to claim 1, wherein, based on that a total mass of the gel skeleton monomer, the flexible additive and the polymerization initiator is 100%, the gel electrolyte precursor comprises the following components: gel skeleton monomer 30-80%; flexible additive 20-60%; polymerization initiator 1-10%;. preferably, a ratio of a molar amount of the lithium salt to a volume of the gel skeleton monomer is 0.1-2 mol/L.

11. (canceled)

12. A solution for preparing a gel electrolyte, comprising the gel electrolyte precursor according to claim 1 and an electrolyte liquid.

13. The solution for preparing a gel electrolyte according to claim 12, wherein, in the solution for preparing a gel electrolyte, a mass ratio of the gel electrolyte precursor to the electrolyte liquid is 0.1:9.9-9.9:0.1; preferably, in the solution for preparing a gel electrolyte, the mass ratio of the gel electrolyte liquid is 4:6-6:4; preferably, the solution for preparing a gel electrolyte is prepared by a method, which comprises mixing the gel electrolyte precursor and an electrolyte liquid, so as to obtain the solution for preparing a gel electrolyte.

14. (canceled)

15. (canceled)

16. A preparation method of a gel electrolyte, comprising subjecting the solution for preparing a gel electrolyte according to claim 12 to in-situ-polymerization gelation, and then baking the same, so as to obtain a gel electrolyte.

17. . The preparation method of a gel electrolyte according to claim 16, wherein a temperature of the in-situ polymerization gelation is 70-75° C.; preferably, the baking is vacuum baking; and a vacuum degree of the vacuum baking isles than or equal to 0.1 kPa; and wherein a temperature of the baking is 80-85° C.

18. (canceled)

19. (canceled)

20. (Canceled)

21. A gel electrolyte prepared by the method according to claim 1, wherein the gel electrolyte has a porous structure; preferably, the gel electrolyte has an elastic porous structure.

22. (canceled)

23. A preparation method of an electrode sheet including a gel electrolyte, comprising: coating an electrode sheet with the solution for preparing a gel electrolyte according to claim 12, subjecting the same to in-situ polymerization, and drying the same, so as to obtain an electrode sheet including a gel electrolyte.

24. The preparation method of an electrode sheet including a gel electrolyte according to claim 23, wherein the electrode sheet comprises a positive electrode sheet and/or a negative electrode sheet.

25. The preparation method of an electrode sheet including a gel electrolyte according to claim 23, wherein a method of the coating comprises dip coating; preferably, the dip coating comprises placing the electrode sheet into a solution for preparing a gel electrolyte; and the electrode sheet is vertically placed in a solution for preparing a gel electrolyte; preferably, the method further comprises wiping the surface of the electrode sheet after the dip coating, and wherein the wiping is performed with dustless paper.

26. (canceled)

27. (canceled)

28. (canceled)

29. (canceled)

30. The preparation method of an electrode sheet including a gel electrolyte according to claim 23, wherein a temperature of the in-situ polymerization is 70-75° C., and a time of the in-situ polymerization is 16-32 h; preferably, the method further comprises wiping an electrode tab of the electrode sheet after the in-situ polymerization, and wherein a solvent is dimethyl sulfoxide for wiping the electrode tab of the electrode sheet preferably, the drying is vacuum drying, and a temperature of the drying is 80-85° C.

31. (canceled)

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. The preparation method of an electrode sheet including a gel electrolyte according to claim 23, wherein the method comprises the following steps: (1) placing an electrode sheet vertically into an aluminum laminated film packaging a solution for preparing a gel electrolyte for 20-30 h, then taking the electrode sheet out, and wiping the surface of the electrode sheet with dustless paper, so as to complete dip coating of the electrode sheet; (2) placing the electrode sheet after dip coating in step (1) into an aluminum laminated film, placing the same at 70-75° C. for in-situ polymerization for 24 h, then taking the electrode sheet out and wiping an electrode tab with dimethyl sulfoxide; (3) wrapping the electrode sheet after in-situ polymerization in step (2) with dustless paper, and placing the same into an oven for vacuum drying at 80-85° C., so as to obtain an electrode sheet including a gel electrolyte.

37. An electrode sheet including a gel electrolyte prepared by the method according to claim 23.

38. The electrode sheet including a gel electrolyte according to claim 37, wherein the gel electrolyte on the electrode sheet including a gel electrolyte has a porous structure; preferably, the gel electrolyte on the electrode sheet including a gel electrolyte has an elastic porous structure.

39. (canceled)

40. A semi-solid battery, wherein at least one of a positive electrode sheet or a negative electrode sheet of the semi-solid battery uses the electrode sheet including a gel electrolyte according to claim 37.

41. . The semi-solid battery according to claim 40, wherein the semi-solid battery comprises at least one of a pouch battery, a cylindrical battery and a square aluminum-case battery; preferably, the semi-solid battery is a pouch battery.

42. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0089] The accompanying drawings are used to provide a further understanding of the technical solutions of the present disclosure, constitute a part of the specification, explain the technical solutions of the present disclosure in conjunction with examples of the present application, and have no limitation on the technical solutions of the present disclosure.

[0090] FIG. 1 is a process flow showing dip coating process of a positive electrode sheet in an example of the present disclosure.

[0091] FIG. 2 is a process flow diagram showing in-situ-polymerization gelation of a positive electrode sheet after dip coating in an example of the present disclosure.

[0092] FIG. 3 is a SEM+EDX image showing the surface of a positive electrode sheet including a gel electrolyte in an example of the present disclosure.

[0093] FIG. 4 is a SEM image showing the surface of a positive electrode sheet including a gel electrolyte in an example of the present disclosure, in which the boxed area is denoted as area A, that is, the lower area.

[0094] FIG. 5 is a SEM image showing the surface of a positive electrode sheet including a gel electrolyte in an example of the present disclosure, in which the boxed area is denoted as area B, that is, the upper area.

[0095] FIG. 6 is an optical image showing an acupuncture safety test of a liquid NCM-Cr battery in Comparative Example 1 of the present disclosure.

[0096] FIG. 7 is an optical image showing an acupuncture safety test of a semi-solid battery (a PVCA gel NCM-Gr battery) in an example of the present disclosure.

DETAILED DESCRIPTION

[0097] The technical solutions of the present disclosure will be further described below with reference to the drawings and through specific embodiments. It should be apparent to those skilled in the art that the embodiments are merely used for a better understanding of the present disclosure, and should not be regarded as a specific limitation of the present disclosure.

[0098] In an embodiment, the present disclosure provides a preparation method of a positive electrode sheet including a gel electrolyte, and the preparation flow diagram of the method is shown in FIG. 1 and FIG. 2, which includes the following steps: [0099] (a) a gel electrolyte precursor and an electrolyte liquid are prepared; [0100] (b) the gel electrolyte precursor and the electrolyte are mixed to obtain a mixed solution, and the mixed solution is packaged in an aluminum laminated film; [0101] (c) a positive electrode sheet is placed vertically into the aluminum laminated film in step (b) for dip coating of the positive electrode sheet; [0102] (d) the positive electrode sheet is subjected to surface treatment after of dip coating, and that is, the surface of the positive electrode sheet is wiped with dustless paper; [0103] (e) the positive electrode sheet in step (d) is placed into a new aluminum laminated film for in-situ polymerization (for example, in-situ polymerization at 75° C. for 24 h); [0104] (f) an electrode tab of the positive electrode sheet after in-situ polymerization is wiped, and for example, the electrode tab is wiped with DMSO first, and then wiped with dry dustless paper; and [0105] (g) the positive electrode sheet in step (f) is subjected to vacuum drying, so as to obtain a positive electrode sheet including a gel electrolyte; the gel electrolyte has an elastic porous structure.

[0106] The typical but non-limiting examples of the present disclosure are described below.

Example 1

[0107] In this example, a gel electrolyte precursor included the following components: a gel skeleton monomer, a flexible additive, a polymerization initiator and a lithium salt; [0108] wherein, the gel skeleton monomer was an acrylonitrile monomer; [0109] the flexible additive was butanedinitrile; [0110] the polymerization initiator was azobisisobutyronitrile; and [0111] the lithium salt was lithium bis(trifluoromethanesulfonyl)imide.

[0112] Based on that a total mass of the gel skeleton monomer, the flexible additive and the polymerization initiator was 100%, the gel electrolyte precursor included the following components: [0113] gel skeleton monomer 58% [0114] flexible additive 38% [0115] polymerization initiator 4%.

[0116] A ratio of a molar amount of the lithium salt to a volume of the gel skeleton monomer was 1 mol/L.

[0117] Components of an electrolyte liquid: a solvent with a volume ratio of EC:DMC:EMC=2:4:4, LiPF.sub.6 with a content of 1.15 mol/L, and 7% FEC.

[0118] A mass ratio of the gel electrolyte precursor to the electrolyte liquid was 1:1 for mixing.

[0119] Positive electrode sheet: a current collector was an aluminum foil of 12 μm, a positive electrode active material was NCM622, a binder was PVDF 5130, and a conductive agent was SP.

[0120] Negative electrode sheet: a current collector was a copper foil of 8 μm, a negative electrode active material was a mixture of artificial graphite and hard carbon, a conductive agent was SP, and a binder was CMC&SBR.

[0121] Preparation method of a negative electrode sheet including a gel electrolyte: [0122] (1) a prepared negative electrode sheet was placed vertically into an aluminum laminated film packaging a solution for preparing a gel electrolyte, hold vertically for 24 h, then taken the electrode sheet out, and wiped on the surface with dustless paper, so as to complete dip coating of the electrode sheet; [0123] (2) the negative electrode sheet after dip coating in step (1) was placed into a new aluminum laminated film, placed at 75° C. for in-situ polymerization for 24 h, and then taken the electrode sheet out, and an electrode tab was wiped with dimethyl sulfoxide; and [0124] (3) the electrode sheet after in-situ polymerization in step (2) was wrapped with dustless paper, and placed into an oven for vacuum drying at 85° C. for 24 h, so as to obtain an electrode sheet including a gel electrolyte.

[0125] A preparation method of the positive electrode sheet including a gel electrolyte differs from the method of the negative electrode sheet merely in that the in-situ polymerization condition was replaced with in-situ polymerization at 75° C. for 17 h; different ovens were used to avoid cross-contamination, and other conditions were the same.

[0126] Assembling a semi-solid battery:

[0127] In this example, a semi-solid battery was prepared by lamination; after lamination, the semi-solid battery was obtained through liquid injection (1.5 g/Ah), standing at 45° C. and formation, which was denoted as a polyacrylonitrile (PAN-SN) gel NCM-Gr battery.

[0128] The negative electrode sheet including a gel electrolyte prepared in Example 1 was tested for the uniformity of the gel formation, and the test method was SEM+EDX; the S element in LiTFSI was used for determination, the electron microscope image was shown in FIG. 3, and it can be seen from the SEM+EDX image that the S element was uniformly distributed, and the gel was formed uniformly from top to bottom in the electrode sheet; the element percentage was used for determination, and as shown in FIG. 4 (the lower area) and FIG. 5 (the upper area), on the same electrode sheet, S element contents of the upper and lower areas are respectively the upper part: 4.1%, the lower part: 4.01%; in the range of 4±0.2%; the gel was formed very uniformly.

[0129] The element distribution table of the lower area in FIG. 4 is shown in Table 1:

TABLE-US-00001 TABLE 1 Atomic Net Mass Normalized Element Number Value (%) Mass (%) Atom C 6 412171 88.31 87.31 90.54 N 7 1384 2.09 2.05 1.82 O 8 8466 3.42 4.46 3.47 F 9 6677 2.08 2.04 1.34 S 16 13464 4.1 4.15 2.83 total: 100.00 100.00 100.00

[0130] The element distribution table of the upper area in FIG. 5 is shown in Table 2:

TABLE-US-00002 TABLE 2 Atomic Net Mass Normalized Element Number Value (%) Mass (%) Atom C 6 193057 87.54 84.54 89.57 N 7 579 2.16 1.5 1.36 O 8 4545 4.16 4.15 3.30 F 9 3019 2.13 1.6 1.07 S 16 8358 4.01 3.98 2.79 total: 100.00 100.00 100.00

Example 2

[0131] This example differs from Example 1 in that, based on that a total mass of the gel skeleton monomer, the flexible additive and the polymerization initiator was 100%, the gel electrolyte precursor included the following components: [0132] gel skeleton monomer 75% [0133] flexible additive 20% [0134] polymerization initiator 5%; [0135] a ratio of a molar amount of the lithium salt to a volume of the gel skeleton monomer was 2 mol/L; and [0136] other parameters and conditions were identical with those in Example 1.

Example 3

[0137] This example differs from Example 1 in that, based on that a total mass of the gel skeleton monomer, the flexible additive and the polymerization initiator was 100%, the gel electrolyte precursor included the following components: [0138] gel skeleton monomer 30% [0139] flexible additive 60% [0140] polymerization initiator 10%; [0141] a ratio of a molar amount of the lithium salt to a volume of the gel skeleton monomer was 0.1 mol/L; and [0142] other parameters and conditions were identical with those in Example 1.

Example 4

[0143] This example differs from Example 1 in that, based on that a total mass of the gel skeleton monomer, the flexible additive and the polymerization initiator was 100%, the gel electrolyte precursor included the following components: [0144] gel skeleton monomer 65% [0145] flexible additive 30% [0146] polymerization initiator 5%; [0147] a ratio of a molar amount of the lithium salt to a volume of the gel skeleton monomer was 1.5 mol/L; and [0148] other parameters and conditions were identical with those in Example 1.

Example 5

[0149] This example differs from Example 1 in that the mass ratio of the gel electrolyte precursor to the electrolyte liquid was replaced with 9:1 from 1:1, and other parameters and conditions were identical with those in Example 1.

Example 6

[0150] This example differs from Example 1 in that the mass ratio of the gel electrolyte precursor to the electrolyte liquid was replaced with 1:9 from 1:1, and other parameters and conditions were identical with those in Example 1.

Example 7

[0151] This example differs from Example 1 in that the flexible additive was replaced with an ionic liquid with equal mass, the ionic liquid had a component of a 1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide salt (PP14TFSI), and other parameters and conditions were identical with those in Example 1.

Example 8

[0152] This example differs from Example 1 in that the lithium salt in the precursor was replaced with lithium perchlorate with equimolar amount, and other parameters and conditions were identical with those in Example 1.

Example 9

[0153] This example differs from Example 1 in that the lithium salt in the precursor was replaced with lithium tetrafluoroborate with equimolar amount, and other parameters and conditions were identical with those in Example 1.

Example 10

[0154] This example differs from Example 1 merely in the coating method used in the preparation process of the negative and positive electrode sheets including a gel electrolyte, which meant dip coating was not used; the mixed solution of the gel electrolyte precursor and the electrolyte liquid was coated on the surface of the electrode sheet, then subjected to in-situ polymerization, and baked, so as to obtain a negative electrode sheet including a gel electrolyte and a positive electrode sheet including a gel electrolyte, and other parameters and conditions were identical with those in Example 1.

[0155] In this example, the gel electrolyte precursor was coated on the surface of the positive electrode sheet by a coating method; after in-situ polymerization, the elemental analysis result of SEM+EDX showed that the surface of the electrode sheet had a high content of gel electrolyte, while the bottom of the electrode sheet (the side near the current collector) had a electrolyte content of 0% approximately; after coating, the upper and bottom of the electrode sheet had an non-uniform content, failing to achieve complete immersion.

Comparative Example 1

[0156] This example differs from Example 1 merely in that the positive and negative electrode sheets had no gel electrolyte, and the prepared positive and negative electrode sheets were directly subjected to lamination, then liquid injection (2.65 g/Ah), standing and formation, so as to obtain a liquid battery, which was denoted as a liquid NCM-Gr (with a positive electrode of ternary material and a negative electrode of graphite and hard carbon) battery.

[0157] The test results of battery rate capability in Example 1 and Comparative Example 1 are shown in Table 3:

TABLE-US-00003 TABLE 3 1 C/0.33 C 1 C/0.5 C 1 C/1 C 1 C/2 C PAN-SN gel Gram 175.05 175.22 172.47 166.09 state NCM-Gr Capacity battery Percentage 100% 100% 99% 96% NCM-Gr Gram 174.45 174.68 172.15 167.37 battery Capacity Percentage 100% 100% 99% 95%

[0158] It can be seen from Table 3 that the rate capability of the PAN-SN gel state NCM-Gr battery of the present disclosure is similar to that of the liquid battery.

[0159] The test results of the battery charge/discharge capacity and initial efficiency in Example 1 and Comparative Example 1 are shown in Table 4;

TABLE-US-00004 TABLE 4 Charge Discharge Initial Capacity Capacity Efficiency (Ah) (Ah) (%) Liquid NCM-Gr battery 0.430 0.375 87.2% PVCA gel state 0.430 0.373 86.7% NCM-Gr battery

[0160] It can be seen from Table 4 that, under the same system, the utilization of PAN-SN electrolyte battery has little difference with the traditional NCM-Gr battery in terms of charge capacity, discharge capacity or initial efficiency, indicating that the gel material of the present disclosure has no side effects on the battery.

[0161] The optical images of the battery acupuncture safety test in Comparative Example 1 and Example 1 are shown in FIG. 6 and FIG. 7, respectively; the semi-solid battery in Example 1 passed the acupuncture test, while the acupuncture caused a fire in Comparative Example 1; it is indicated that the semi-solid battery prepared by using the gel electrolyte precursor of the present disclosure has higher safety.

Comparative Example 2

[0162] This comparative example differs from Example 1 in that the gel electrolyte precursor had no flexible additive, and other parameters and conditions were identical with those in Example 1.

Comparative Example 3

[0163] This comparative example differs from Example 1 in that the gel electrolyte precursor had no lithium salt, and other parameters and conditions were identical with those in Example 1.

Comparative Example 4

[0164] This comparative example differs from Example 1 in that the lithium salt in Example 1 was replaced with LiPF6, and other parameters and conditions were identical with those in Example 1.

[0165] This comparative example used LiPF.sub.6 as a lithium salt of the gel electrolyte precursor; after gelation at 75° C., the gel could not be fully formed, a part of material was still liquid, and the color changed to dark-brown.

Performance Testing:

[0166] The batteries prepared in examples and comparative examples were tested for rate capability, initial efficiency, cycle performance and safety performance (acupuncture test), and the test results are shown in Table 5.

[0167] In the test, rate capability test conditions: [0168] a) constant-current and constant-voltage charging: 0.33 C CC 4 h to 4.25 V, CV to 0.05 C; [0169] b) standing for 5 min; [0170] c) constant-current discharging: 0.33 C DC to 2.5 V; [0171] d) standing for 5 min; [0172] e) constant-current and constant-voltage charging: 0.33 C CC 4 h to 4.25 V, CV to 0.05 C; [0173] f) standing for 5 min; and [0174] g) constant-current discharging: 1 C DC to 2.5 V.

[0175] The rate capability of 1 C/0.33 C was obtained by the test, and the test parameters of rate capability under other circumstances, such as 1 C/0.5 C, 1 C/1 C and 1 C/2 C, referred to the above conditions.

[0176] The initial efficiency test conditions: at an ambient temperature of 25° C.; [0177] a) constant-current and constant-voltage charging: 0.05 C CC 22 h to 4.25 V, CV to 0.01 C; [0178] b) standing for 10 min; and [0179] c) constant-current discharging: 0.05 C DC to 2.5 V. [0180] Cycle performance test conditions: at a test temperature of 25° C.; [0181] a) constant-current and constant-voltage charging: 1 C CC to 4.25 V, CV to 0.05 C; [0182] b) standing for 5 min; c) constant-current discharging: 1 C DC to 2.5 V; and [0183] d) step a)-step c) were performed circularly for 100 times. [0184] Safety (acupuncture test) conditions: [0185] with reference to GBT31485-2015 Safety requirements and test methods for traction battery of electric vehicle, the steps are as follows: [0186] a) a single cell was charged; [0187] b) with a φ6.5 mm high-temperature resistance steel needle (a cone angle of the needle tip was 50° , and the needle surface was smooth and had no rust, oxide layer or oil stains), the cell was penetrated at a speed of 25 mm/s from a direction perpendicular to the storage battery plate, the penetration position was close to the geometric center of the pierced surface, and the steel needle stayed in the cell; and [0188] c) observation for 1 h.

[0189] The test results are shown in Table 5;

TABLE-US-00005 TABLE 5 Initial Retention Efficiency Rate after Acupuncture 1 C/0.33 C % 100 Cycles % Test Example 1 92.1% 86.7% 97.3% Passed Example 2 86.6% 75.5% 75.7% Passed Example 3 83.3% 77.6% 85.0% Passed Example 4 92.7% 86.9% 97.7% Passed Example 5 39.5% 55.2% 65.8% Passed Example 6 93.7% 87.1% 97.7% Failed Example 7 92.5% 86.6% 97.2% Passed Example 8 76.5% 71.2% 79.6% Passed Example 9 86.8% 69.2% 79.8% Passed Example 10 73.5% 72.2% 80.6% Failed Comparative 93.1% 87.2% 97.8% Failed Example 1 Comparative Failed to form gel Failed Example 2 Comparative 74.6% 60.6% 78.5% Failed Example 3 Comparative Failed to fully form gel, and Failed Example 4 changed to black in color

[0190] As can be seen from Table 5, the battery is significantly improved in safety, which is assembled from the gel electrolyte obtained by mixing the gel electrolyte precursor of the present disclosure and the electrolyte liquid and subjecting to in-situ polymerization gelation, and the prepared semi-solid battery can realize electrical performances similar to that of the liquid battery, which achieves the effect of improving the battery safety while maintaining high electrical performances.

[0191] As can be seen from the comparison of Examples 1-4, the content of each component in the gel electrolyte precursor of the present disclosure will affect the performance of the semi-solid battery; when the content of each component meets the following conditions, the prepared semi-solid battery will have more significant improvements in the electrical performances and safety performance: based on that a total mass of the gel skeleton monomer, the flexible additive and the polymerization initiator is 100%, the gel electrolyte precursor includes the following components: the gel skeleton monomer with a mass percentage of 50-65%, the flexible additive with a mass percentage of 30-45%, and the polymerization initiator with a mass percentage of 2-5%.

[0192] As can be seen from the comparison of Examples 1 and 5-6, when a mass ratio of the gel electrolyte precursor to the electrolyte liquid is 0.1:9.9-9.9:0.1, high electrochemical performances and safety performance can be obtained; when the mass ration is 4:6-6:4, the improvement effect is better; when the mass ration is 1:1, the improvement effect is the best.

[0193] As can be seen from the comparison of Example 1 and Example 7, the semi-solid battery, which is obtained by mixing the electrolyte liquid and the gel electrolyte precursor prepared by adding the ionic liquid as a flexible additive, has performances similar to the liquid battery; however, the ionic liquid has the problem of high cost.

[0194] As can be seen from the comparison of Examples 1, 8 and 9, when lithium bis(trifluoromethanesulfonyl)imide is selected as the lithium salt in the gel electrolyte precursor of the present disclosure, the semi-solid battery will have better performances than those using lithium perchlorate or lithium borate.

[0195] As can be seen from the comparison of Example 1 and Example 10, the method of the present disclosure uses dip coating, which is more conducive to improving the battery in electrochemical performance and safety performance.

[0196] As can be seen from the comparison of Example 1 and Comparative Example 1, the battery, which is assembled from the gel electrolyte prepared by the gel electrolyte precursor of the present disclosure, can realize electrical performances similar to the liquid battery, and even has higher safety performance.

[0197] In Comparative Example 2, gel cannot be formed without flexible additive, and in the absence of flexible additive, the polymerization of skeleton monomers will increase the crystallinity of material, resulting in material pulverizing and precipitating; in Comparative Example 3, gel can be formed without lithium salt, but the conductivity of the gel system will decrease, the performance will be worse compared with those added lithium salt, and the safety performance will also deteriorate.

[0198] As can be seen from the comparison of Example 1 and Comparative Example 4, when lithium hexafluorophosphate is used as a lithium salt in the precursor, gel cannot be fully formed, the color changes to black, and the safety is poor.