Electrolyte materials and applications thereof

Abstract

The application provides an electrolyte material and application thereof, the electrolyte material is a core-shell structure, the core of the core-shell structure comprises a PTC material, and the shell of the core-shell structure comprises a sulfur ion-containing conductive polymer; the electrolyte material can improve the cycle performance and rate performance of a battery under normal use conditions of the battery due to the high shell conductivity; when a safety problem occurs, the battery will heat due to internal short circuit, and in the heating process, the shell of the electrolyte material will melt, the PTC material is released, the internal resistance of the battery is improved, and the occurrence of thermal runaway of the battery is prevented.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and relates to an electrolyte material, in particular to an electrolyte material and application thereof. BACKGROUND

[0002] At present, commercial lithium batteries are difficult to improve in high energy density, and solid-state batteries have been put forward as the next generation of batteries, but the development of solid-state batteries is difficult, the process requirements are high, and mass production cannot be realized at present, so semi-solid-state batteries emerge as the times require as a transitional product. As a transitional state between traditional liquid-state batteries and all-solid-state batteries, semi-solid-state batteries are very close to traditional liquid-state batteries in terms of operability, rate performance and cycle performance of the battery, and the safety performance is better than that of traditional liquid-state batteries.

[0003] At present, among the methods for preventing thermal runaway of lithium ion batteries, using flame-retardant electrolyte is the most economical and simple strategy, which can effectively reduce the risk of thermal runaway of lithium ion batteries. For example, PTC (thermistor) materials can be added for flame retardation, but the addition of PTC materials often reduces the cycle performance and rate performance of the battery, and has a great influence on the electrical performance of the battery. If the amount added is small, it will not play a role in flame retardation, so the current battery with PTC material is difficult to balance the flame retardation performance and electrochemical performance.

[0004] Based on the above research, how to provide an electrolyte material which is used for semi-solid-state batteries, and can balance the flame retardation performance and electrochemical performance at the same time is a problem that needs to be solved at present. SUMMARY

[0005] The purpose of the application is to provide an electrolyte material and its application. The electrolyte material is added to the electrode, and the addition of the electrolyte material will not affect the cycle performance and rate performance of the battery under normal use conditions, so as to have excellent electrochemical performance. When encountering conditions such as needle puncture, compression, impact, overcharge, forced short circuit, hot box or thermal shock, the battery will heat due to internal short circuit, and in the heating process, the electrolyte material can increase the internal resistance of the battery and prevent the occurrence of thermal runaway of the battery.

[0006] In a first aspect, the application provides an electrolyte material, which is a core-shell structure, the core of the core-shell structure comprises a PTC (thermistor) material; and the shell of the core-shell structure comprises a sulfur ion-containing conductive polymer.

[0007] The electrolyte material has a core-shell structure. When the battery is short-circuited and generates heat, the shell of the electrolyte material melts and breaks, releasing the PTC material, which plays a role in flame retardation and prevents the battery from thermal runaway. In a normal use state, the PTC material is wrapped by the sulfur ion-containing conductive polymer material, which does not affect the cycle performance and rate performance of the battery. The sulfur ion-containing conductive polymer material has high electrical conductivity, which can improve the rate of lithium ion batteries, and also has the effects of improving the compaction density and reducing the swelling of the negative electrode.

[0008] Preferably, the monomers of the sulfur ion-containing conductive polymer are polymerized to include any one or a combination of at least two of the following compounds.

[0009]

[0010] Preferably, the sulfur ion-containing conductive polymer includes any one or a combination of at least two of polypropylene-1,3-sulfolane, poly2,3-dihydrothiophene-1,1-dioxide or poly3-cyclobutene sulfone, and a typical but non-limiting combination includes a combination of polypropylene-1,3-sulfolane and poly2,3-dihydrothiophene-1,1-dioxide, or a combination of polypropylene-1,3-sulfolane and poly3-cyclobutene sulfone, preferably polypropylene-1,3-sulfolane.

[0011] The sulfur ion-containing conductive polymer has good elasticity and electrical conductivity, can reduce the swelling of the negative electrode, and adding the electrolyte material with the core-shell structure to the semi-solid battery can improve the safety of the semi-solid battery. At the same time, the sulfur ion-containing conductive polymer is fully dispersed in the electrode, significantly improves the content of the solid electrolyte, ensures the uniform distribution of the solid electrolyte, improves the lithium ion conduction, ensures the normal migration of lithium ions in the electrode, does not affect the electrical performance of the battery, and can also ensure that the electrode has a high compaction density.

[0012] Preferably, the PTC material includes polystyrene sulfonic acid and / or tris(2,2,2-trifluoroethyl) phosphite.

[0013] Preferably, the content of the PTC material is 1wt% to 99wt%, for example, it can be 1wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt% or 99wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable, preferably 20wt% to 95wt%, and further preferably 50wt% to 90wt%, based on the mass of the electrolyte material.

[0014] Preferably, the thickness of the shell is 10 μm to 500 μm, for example, can be 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm, but not limited to the listed values, other values not listed in the range of values are also applicable.

[0015] Preferably, the shell further comprises a lithium salt and an additive.

[0016] Preferably, the additive comprises any one of polyvinyl sulfone, PEGMEMA (polyethylene glycol monomethyl ether methacrylate), polytriethylene glycol diacrylate or polytetraethylene glycol tetraacrylate or a combination of at least two thereof, typically but not limitedly, a combination of polyvinyl sulfone and PEGMEMA, or a combination of polytriethylene glycol diacrylate and polytetraethylene glycol tetraacrylate.

[0017] The additive described in the present application functions as a crosslinking agent, allowing the shell layer to form a network structure, better coating the PTC material.

[0018] Preferably, the lithium salt comprises any one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethylsulfonate (LiCF3SO3), lithium tetrafluoro oxalate phosphate (LiTFOP), lithium trioxalate phosphate (LiTOP), lithium bis-trifluoromethylsulfonylimide (LiTFSI), lithium bis-perfluoroethylsulfonylimide (LiFSI), lithium trifluoromethylsulfonyl normal perfluorobutylsulfonylimide (LiFNTFSI) or lithium bis-oxalate borate (LiBOB) or a combination of at least two thereof, typically but not limitedly, a combination of lithium bis-trifluoromethylsulfonylimide and lithium hexafluorophosphate, a combination of lithium bis-trifluoromethylsulfonylimide and lithium tetrafluoroborate, a combination of lithium bis-trifluoromethylsulfonylimide and lithium perchlorate, or a combination of lithium hexafluorophosphate and lithium hexafluoroarsenate, preferably lithium bis-trifluoromethylsulfonylimide.

[0019] Preferably, the content of the sulfur ion-containing conductive polymer is 80 wt% to 89.8 wt% based on the mass of the shell, for example, can be 80 wt%, 85 wt% or 89.8 wt%, but not limited to the listed values, other values not listed in the range of values are also applicable.

[0020] Preferably, the content of the lithium salt is 10 wt% to 19.5 wt% based on the mass of the shell, for example, can be 10 wt%, 15 wt% or 19.5 wt%, but not limited to the listed values, other values not listed in the range of values are also applicable.

[0021] The preparation method of the electrolyte material described in the present application comprises the following steps:

[0022] The mixed PTC dispersion liquid is mixed with the sulfur ion-containing conductive polymer dispersion liquid, and the resultant mixture is dried, washed, and dried to obtain the electrolyte material.

[0023] Preferably, the temperature of the mixed PTC dispersion liquid and the sulfur ion-containing conductive polymer dispersion liquid is 65-75°C, for example, 65°C, 70°C, or 75°C, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0024] Preferably, the time of the mixed PTC dispersion liquid and the sulfur ion-containing conductive polymer dispersion liquid is 3.5-4.5h, for example, 3.5h, 4h, or 4.5h, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0025] The PTC dispersion liquid is obtained by mixing the PTC material with a dispersant, treating with an emulsifier, and adjusting the pH.

[0026] Preferably, the temperature of the mixed PTC material and dispersant is 20-35°C, for example, 20°C, 25°C, 30°C, or 35°C, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0027] Preferably, the mass ratio of the PTC material, dispersant, and emulsifier is 1:(2.5-3.5):(0.05-0.15), for example, 1:2.5:0.05, 1:3:0.1, or 1:3.5:0.15, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0028] Preferably, the dispersant comprises deionized water and / or anhydrous ethanol.

[0029] Preferably, the emulsifier comprises polyacrylamide.

[0030] Preferably, the pH of the PTC dispersion liquid is 3-4, for example, 3, 3.5, or 4, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0031] Preferably, the pH of the PTC dispersion liquid is adjusted using acetic acid.

[0032] Preferably, the mass fraction of the acetic acid is 8-12wt%, for example, 8wt%, 10wt%, or 12wt%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0033] The dispersion of the sulfur-containing ion-conducting polymer includes: dispersing monomers of the sulfur-containing ion-conducting polymer using a lithium salt, an initiator, an additive monomer, and polymerizing the monomers.

[0034] Preferably, the temperature of the dispersion is 80°C to 90°C, such as 80°C, 85°C, or 90°C, but is not limited to the listed values, and other non-listed values within the range of values are also applicable.

[0035] Preferably, the dispersant of the dispersion includes deionized water.

[0036] Preferably, the mass ratio of the monomers of the sulfur-containing ion-conducting polymer, the lithium salt, and the initiator is (80 to 89.8):(10 to 19.5):(0.1 to 0.5), such as 80:19.5:0.5 or 89.8:10:0.2, but is not limited to the listed values, and other non-listed values within the range of values are also applicable.

[0037] Preferably, the molar ratio of the monomers of the sulfur-containing ion-conducting polymer and the additive monomer is (93.5 to 94.5):(5.5 to 6.5), such as 93.5:6.5, 94.5:5.5, or 94:6, but is not limited to the listed values, and other non-listed values within the range of values are also applicable.

[0038] Preferably, the initiator includes any one or a combination of at least two of azobisisobutyronitrile, azobisisoheptyl nitrile, dimethyl azobisisobutyrate, hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, t-butyl benzoyl peroxide, or methyl ethyl ketone peroxide, and a typical but non-limiting combination includes a combination of azobisisobutyronitrile and azobisisoheptyl nitrile, or a combination of dimethyl azobisisobutyrate and hydrogen peroxide.

[0039] Preferably, the additive monomer includes any one or a combination of at least two of ethylene sulfone, PEGMEMA, triethylene glycol diacrylate, or pentaerythritol tetraacrylate, and a typical but non-limiting combination includes a combination of ethylene sulfone and PEGMEMA, or a combination of triethylene glycol diacrylate and pentaerythritol tetraacrylate.

[0040] Preferably, the temperature of the drying is 75°C to 85°C, such as 75°C, 80°C, or 85°C, but is not limited to the listed values, and other non-listed values within the range of values are also applicable.

[0041] Preferably, the time of the drying is 22h to 26h, such as 22h, 24h, or 26h, but is not limited to the listed values, and other non-listed values within the range of values are also applicable.

[0042] The polymer powder obtained after drying is subjected to removal of unreacted substances.

[0043] Preferably, the vacuum degree for removal of unreacted substances is 0.1 Pa or less, for example, it can be 0.1 Pa, 0.01 Pa, 0.0001 Pa or 0.00001 Pa, but is not limited to the listed values, and other values not listed in the value range are also applicable, and preferably, it is 0.1 Pa to 0.0001 Pa.

[0044] Preferably, the temperature for removal of unreacted substances is 75°C to 85°C, for example, it can be 75°C, 80°C or 85°C, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0045] Preferably, the time for removal of unreacted substances is 22 h to 26 h, for example, it can be 22 h, 24 h or 26 h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0046] Preferably, the cleaning liquid for cleaning includes cyclohexane and / or dimethyl carbonate.

[0047] Preferably, the number of times of cleaning is 3 to 10 times, for example, it can be 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times or 10 times.

[0048] After cleaning, the polymer powder is subjected to suction filtration and then drying, and the purpose of cleaning is to further remove unreacted substances.

[0049] Preferably, the temperature for drying is 75°C to 85°C, for example, it can be 75°C, 80°C or 85°C, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0050] Preferably, the time for drying is 22 h to 26 h, for example, it can be 22 h, 24 h or 26 h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0051] In a second aspect, the present application provides an electrode comprising the electrolyte material of the first aspect.

[0052] Preferably, the electrolyte material of the first aspect is added in the homogenization process of the electrode.

[0053] The electrolyte material of the present application is added in the homogenization step in the electrode preparation process, and has little effect on other properties of the battery. When a low amount is added, for example, when the addition amount is only 2 wt%, the needle puncture, hot box and overcharge of the battery can be minimized.

[0054] Preferably, the electrolyte material is added to the positive electrode slurry.

[0055] In a third aspect, the present application provides an electrochemical device comprising the electrode according to the second aspect.

[0056] Preferably, the electrochemical device comprises a semi-solid lithium ion battery.

[0057] The present application uses a sulfur ion-containing conductive polymer material to coat a PTC material to form a core-shell material. When the battery encounters a safety problem and generates heat, the sulfur ion-containing conductive polymer material melts and breaks, releasing the PTC material to increase the internal resistance of the battery, thereby preventing the battery from overheating. In a normal use state, the PTC material is wrapped by the sulfur ion-containing conductive polymer material and does not affect the cycle performance and rate performance of the battery. In addition, the sulfur ion-containing conductive polymer material has good elasticity and can reduce the expansion of the negative electrode. Compared with a conventional electrode added with an ion-conducting polymer material, the electrolyte material with the core-shell structure according to the present application can improve the safety of the semi-solid battery, fully disperse the sulfur ion-containing conductive polymer in the electrode, significantly increase the content of the solid-state electrolyte in the electrode, ensure the uniform distribution of the electrolyte material, improve the lithium ion conduction, ensure the normal migration of lithium ions in the electrode, does not affect the electrical performance of the battery, and can also ensure that the electrode has a high compaction density, so that the electrode is not prone to extension. DETAILED DESCRIPTION

[0058] The technical solutions of the present application are further illustrated by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0059] Embodiment 1

[0060] The present embodiment provides an electrolyte material, which has a core-shell structure. The core comprises polystyrene sulfonic acid, and the shell comprises polypropylene-1,3-sulfonic acid lactone, lithium bis-trifluoromethylsulfonylimide, polyethylene sulfone and PEGMEMA.

[0061] The content of the polystyrene sulfonic acid is 70wt% based on the mass of the electrolyte material.

[0062] The thickness of the shell is 200μm.

[0063] The content of the polypropylene-1,3-sulfonic acid lactone is 80wt% and the content of the lithium bis-trifluoromethylsulfonylimide is 19.5wt% based on the mass of the shell.

[0064] The preparation method of the electrolyte material comprises the following steps:

[0065] The polystyrene sulfonic acid dispersion liquid is mixed with the polypropylene-1,3-sulfolactone dispersion liquid at 70℃ for 4h, the obtained mixture is dried at 80℃ for 24h, the obtained polymer powder is heated at 80℃ for 24h under a vacuum degree of 0.001Pa, and then washed with cyclohexane and dimethyl carbonate for 6 times, and then dried at 80℃ for 24h after filtration to obtain the electrolyte material;

[0066] The polystyrene sulfonic acid dispersion liquid is obtained by stirring and mixing polystyrene sulfonic acid and deionized water at 25℃, and then treating with polyacrylamide and adjusting the pH to 3.5 with acetic acid;

[0067] The mass ratio of the polystyrene sulfonic acid, deionized water and polyacrylamide is 1:3:0.1, and the mass fraction of the acetic acid is 10wt%;

[0068] The polypropylene-1,3-sulfolactone dispersion liquid is obtained by dispersing propylene-1,3-sulfolactone, lithium bis(trifluoromethylsulfonyl)imide, azobisisobutyronitrile, ethylene sulfone, PEGMEMA and deionized water at 85℃;

[0069] The mass ratio of the propylene-1,3-sulfolactone, lithium bis(trifluoromethylsulfonyl)imide and azobisisobutyronitrile is 80:19.5:0.5, and the molar ratio of the propylene-1,3-sulfolactone, ethylene sulfone and PEGMEMA is 94:3:2.5.

[0070] Example 2

[0071] The electrolyte material provided in this example is of a core-shell structure, the core comprises tris(2,2,2-trifluoroethyl)phosphite, and the shell comprises poly-3-cyclobutene sulfone, lithium hexafluorophosphate, polyethylene sulfone and PEGMEMA;

[0072] The content of the polystyrene sulfonic acid is 5wt% based on the mass of the electrolyte material;

[0073] The thickness of the shell is 300μm;

[0074] The content of the poly-3-cyclobutene sulfone is 89wt% and the content of the lithium hexafluorophosphate is 10wt% based on the mass of the shell;

[0075] The preparation method of the electrolyte material comprises the following steps:

[0076] The polystyrene sulfonic acid dispersion liquid is mixed with the poly-3-cyclobutene sulfone dispersion liquid at 65℃ for 4.5h, the obtained mixture is dried at 85℃ for 22h, the obtained polymer powder is heated at 85℃ for 22h under a vacuum degree of 0.1Pa, and then washed with cyclohexane and dimethyl carbonate for 10 times, and then dried at 75℃ for 26h after filtration to obtain the electrolyte material;

[0077] The polystyrene sulfonic acid dispersion liquid is obtained by stirring and mixing polystyrene sulfonic acid and deionized water at 35℃, then treating with polyacrylamide, and adjusting pH to 3 with acetic acid;

[0078] The mass ratio of the polystyrene sulfonic acid, deionized water and polyacrylamide is 1:3.5:0.15; the mass fraction of the acetic acid is 12wt%;

[0079] The poly-3-cyclobutenyl sulfone dispersion liquid is obtained by dispersing 3-cyclobutenyl sulfone, lithium hexafluorophosphate, azobisisobutyronitrile, ethylene sulfone, PEGMEMA and deionized water at 90℃;

[0080] The mass ratio of the 3-cyclobutenyl sulfone, lithium hexafluorophosphate and azobisisobutyronitrile is 89.8:10:0.2; the molar ratio of the 3-cyclobutenyl sulfone, ethylene sulfone and PEGMEMA is 93.5:3.5:3.

[0081] Example 3

[0082] The electrolyte material is a core-shell structure, the core comprises polystyrene sulfonic acid, and the shell comprises poly-2,3-dihydrothiophene-1,1-dioxide, lithium tetrafluoroborate, polytriethylene glycol dipropyl acrylate and poly-pentaerythritol tetraacrylate;

[0083] The content of the polystyrene sulfonic acid is 15wt%, based on the mass of the electrolyte material;

[0084] The thickness of the shell is 50μm;

[0085] The content of the poly-2,3-dihydrothiophene-1,1-dioxide is 84wt%, and the content of the lithium tetrafluoroborate is 15wt%, based on the mass of the shell;

[0086] The preparation method of the electrolyte material comprises the following steps:

[0087] The polystyrene sulfonic acid dispersion liquid and the poly-2,3-dihydrothiophene-1,1-dioxide dispersion liquid are mixed at 75℃ for 3.5h, the obtained mixed liquid is dried at 75℃ for 26h, the obtained polymer powder is heated at 75℃ under a vacuum degree of 0.01Pa for 26h, then washed with cyclohexane and dimethyl carbonate for 3 times, filtered, and dried at 85℃ for 22h, to obtain the electrolyte material;

[0088] The polystyrene sulfonic acid dispersion liquid is obtained by stirring and mixing polystyrene sulfonic acid and deionized water at 20℃, then treating with polyacrylamide, and adjusting pH to 4 with acetic acid;

[0089] The mass ratio of the polystyrene sulfonic acid, deionized water and polyacrylamide is 1:2.5:0.05; the mass fraction of the acetic acid is 8wt%;

[0090] The poly-2,3-dihydrothiophene-1,1-dioxide dispersion is obtained by dispersing 2,3-dihydrothiophene-1,1-dioxide, lithium tetrafluoroborate, azobisisobutyronitrile, triethylene glycol diacrylate, pentaerythritol tetraacrylate and deionized water at 80℃;

[0091] The mass ratio of the 2,3-dihydrothiophene-1,1-dioxide, lithium tetrafluoroborate and azobisisobutyronitrile is 84.5:15:0.5; the molar ratio of the 2,3-dihydrothiophene-1,1-dioxide, triethylene glycol diacrylate and pentaerythritol tetraacrylate is 94.5:3.5:2.

[0092] The electrolyte material of Example 4 is the same as that of Example 1 except that the type of PTC material shown in Table 2 is changed.

[0093] Examples 5 and 6 are the same as Example 1 except that the content of the PTC material shown in Table 3 is changed.

[0094] Examples 7 and 8 are the same as Example 1 except that the thickness of the shell shown in Table 4 is changed.

[0095] Comparative Examples 1 and 2 are the same as Example 1 except that the material of the shell shown in Table 6 is changed;

[0096] Comparative Example 2 is the same as Example 1 except that the combination of sulfur powder and polymethyl methacrylate is used instead of poly-3-cyclobutenyl sulfone, the molar ratio of sulfur powder and polymethyl methacrylate is 1:1, and the preparation method is correspondingly changed.

[0097] Application Examples 1 to 8 provide a semi-solid lithium ion battery, based on the mass of the positive electrode slurry for preparing the semi-solid lithium ion battery, 5wt% of the electrolyte material is added to the positive electrode slurry; the electrolyte material added to the positive electrode slurry of Application Examples 1 to 8 respectively corresponds to the electrolyte material provided by Examples 1 to 8.

[0098] Application Example 9 provides a semi-solid lithium ion battery, based on the mass of the negative electrode slurry for preparing the semi-solid lithium ion battery, 5wt% of the electrolyte material provided by Example 1 is added to the negative electrode slurry.

[0099] Example 10 provides a semi-solid lithium ion battery, based on the mass of the positive electrode slurry used to prepare the semi-solid lithium ion battery, 2.5wt% of the electrolyte material provided in Example 1 is added to the positive electrode slurry; based on the mass of the negative electrode slurry used to prepare the semi-solid lithium ion battery, 2.5wt% of the electrolyte material provided in Example 1 is added to the negative electrode slurry.

[0100] Comparative Examples 1-2 provide a semi-solid lithium ion battery, based on the mass of the positive electrode slurry used to prepare the semi-solid lithium ion battery, 5wt% of an electrolyte material is added to the positive electrode slurry; the electrolyte material added to the positive electrode slurry of Comparative Examples 1-2 corresponds to the electrolyte material provided in Comparative Examples 1-2, respectively.

[0101] The positive electrode slurry and the negative electrode slurry are coated on an aluminum foil, respectively, to obtain a positive electrode and a negative electrode, with a polypropylene microporous membrane (Celgard-2400) as a separator, 1 mo / L of LiPF6 / EC+DEC+DMC as an electrolyte (EC is ethylene carbonate, EMC is ethyl methyl carbonate, DMC is dimethyl carbonate, and the volume ratio of EC, DMC and EMC is 1:1:1), and assembled into a semi-solid lithium ion battery according to the general process for preparing lithium ion batteries; wherein the positive electrode slurry comprises 95:3:2:40 of LNCM (LiNi 0.8 Co 0.1 Mn 0.1 O2), conductive carbon black, polyvinylidene fluoride and N-methyl pyrrolidone, and the negative electrode slurry comprises 94:1.5:1.5:0.8:40 of graphite, conductive carbon black, butadiene-styrene rubber, sodium carboxymethyl cellulose and deionized water.

[0102] Needle puncture test conditions: according to the safety requirements and test methods of GBT 31485-2015, charge according to the requirements of GBT 31485-2015; specifically including: using a φ5mm high-temperature-resistant steel needle (the conical angle of the needle tip is 45°), puncturing the battery at a speed of 25±5mm / s, observing for 1h, and recording the highest temperature of the battery.

[0103] Overcharge test conditions: according to the safety requirements and test methods of GBT 31485-2015, charge according to the requirements of GBT 31485-2015; specifically including: constant current charging at 1C current to 1.5 times the cutoff voltage of the obtained semi-solid battery.

[0104] 150°C hot box test conditions: according to the safety requirements and test methods of GBT 31485-2015; specifically including: the oven is raised from room temperature to 150±2°C at a rate of 5°C / min, and after maintaining this temperature for 30min, the heating is stopped; observing for 1h, and recording the highest temperature of the obtained semi-solid battery.

[0105] The above is the safety test: L0 in the test result is no heating, L1 is heating, L2 is liquid leakage, L3 is smoking, L4 is fire, and L5 is explosion.

[0106] The first coulombic efficiency test: the obtained solid-state battery is charged to 4.2V at 1 / 3C and 0.05C at 25°C, and after standing for 5min, it is discharged to 2.5V at 1 / 3C, to obtain the charge capacity and discharge capacity, and the first coulombic efficiency is calculated.

[0107] Normal temperature cycle test conditions: the obtained solid-state battery is charged to 4.2V at 1 / 3C and 0.05C at 25°C, and after standing for 5min, it is discharged to 2.5V at 1 / 3C, and the cycle is repeated 1000 times to obtain the normal temperature cycle retention rate.

[0108] Rate performance test conditions: rate performance = 2C capacity / 0.33C capacity x 100%.

[0109] The test results are shown in Tables 1 to 6:

[0110] Table 1

[0111]

[0112] Table 2

[0113]

[0114] Table 3

[0115]

[0116] Table 4

[0117]

[0118] Table 5

[0119]

[0120] Table 6

[0121]

[0122] The following points can be seen from the above tables:

[0123] (1) As can be seen from application examples 1 and 5 to 6, the content of the PTC material described in application examples 5 to 6 is not within the preferred range, and compared with application example 1, the comprehensive performance of the electrolyte material provided is decreased; therefore, it can be known that the content of the PTC material described in the application is within the preferred range, which can make the PTC material more effectively play a flame-retardant role, and at the same time improve the comprehensive performance of the electrolyte material.

[0124] (2) from application example 1 and application examples 7 to 8, the thickness of the shell in application examples 7 to 8 is not in the preferred range, compared with application example 1, the comprehensive performance of the electrolyte material provided is reduced; thus, the thickness of the shell is in the preferred range, which is beneficial to better coating of the shell on the PTC material, so that the PTC material does not affect the performance of the electrolyte material under normal conditions, and at the same time, the shell can be more effectively melted under high temperature conditions to release the PTC material.

[0125] (3) from application example 1 and application examples 9 to 10, the electrolyte material in application example 9 is added to the negative electrode slurry, and the electrolyte material in application example 10 is added to the positive electrode slurry at a content of 2.5wt%, and to the negative electrode slurry at a content of 2.5wt%, compared with application example 1, the comprehensive performance of the lithium ion battery provided by application examples 9 and 10 is reduced, thus, it is known that adding the electrolyte material in the application to the positive electrode can better play a role.

[0126] (4) from application example 1 and comparative application example 1, although comparative application example 1 is also a core-shell structure, the ion conductive polymer material included in the shell does not contain sulfur element, compared with application example 1, the shell conductivity is reduced, and the comprehensive performance of the obtained semi-solid battery is reduced; thus, it is known that through reasonable matching of the core and shell materials, and using ion conductive polymer material containing sulfur, an electrolyte material with excellent comprehensive performance can be obtained.

[0127] (5) from application example 1 and comparative application example 2, the ion conductive polymer material included in the shell in comparative application example 2 also does not contain sulfur element, even if sulfur powder is doped, due to poor dispersibility of the doped sulfur powder, the sulfur powder is not uniformly doped, on the other hand, the doped sulfur powder cannot achieve the same effect as adding sulfur-containing conductive particle polymer, and cannot achieve the purpose of improving the ion conductivity and other properties of the shell.

[0128] In summary, the present application provides an electrolyte material and its application, the shell has high conductivity under normal use of the battery, which can improve the cycle performance and rate performance of the battery; when safety problems occur, the battery will heat due to internal short circuit, in the heating process, the shell of the electrolyte material will melt, release the PTC material, and improve the internal resistance of the battery, so as to prevent the occurrence of thermal runaway of the battery in a short time.

[0129] The above only describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. An electrolyte material, characterized by, The electrolyte material is a core-shell structure; The core of the core-shell structure comprises a PTC material; the content of the PTC material is 50wt% to 90wt% based on the mass of the electrolyte material; The shell of the core-shell structure is composed of a sulfur ion-containing conductive polymer, a lithium salt and an additive; in the shell, the content of the sulfur ion-containing conductive polymer is 80wt% to 89.8wt%, the content of the lithium salt is 10wt% to 19.5wt%, and the rest is the additive, based on the mass of the shell; The monomer for polymerizing the sulfur ion-containing conductive polymer comprises any one or a combination of at least two of the following compounds; ； The additive comprises any one or a combination of at least two of polyvinyl sulfone, PEGMEMA, polytriethylene glycol diacrylate or polytrimethylolpropane tetraacrylate; The PTC material comprises polystyrene sulfonic acid and / or tris(2,2,2-trifluoroethyl) phosphite.

2. The electrolyte material of claim 1, wherein, The thickness of the shell is 10μm to 500μm.

3. An electrode characterized by, The electrode comprises the electrolyte material as claimed in claim 1 or 2.

4. An electrochemical device, characterized by, The electrochemical device comprises the electrode as claimed in claim 3.

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