Battery-type lithium-ion capacitor and electronic device

Abstract

The present invention provides a battery-type lithium-ion capacitor and an electronic device. The battery-type lithium-ion capacitor comprises a negative electrode sheet. The negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer provided on at least one surface of the negative electrode current collector. The negative electrode active layer comprises a negative electrode active material, and the negative electrode active material comprises hard carbon and graphite. In the negative electrode active material, the mass percentage of graphite is 2-45%. In the present invention, the graphite in the negative electrode sheet can reduce the consumption of lithium ions by the battery-type lithium-ion capacitor when charging and discharging for the first time, which, overall, improves the efficiency of the battery-type lithium-ion capacitor during charging and discharging for the first time, reduces capacity loss of the battery-type lithium-ion capacitor during charging and discharging, and increases the energy density of the battery-type lithium-ion capacitor.

Description

Battery-type lithium ion capacitor and electronic device TECHNICAL FIELD

[0001] The present application relates to a battery-type lithium ion capacitor and an electronic device, and belongs to the technical field of capacitors. BACKGROUND

[0002] The battery-type lithium ion capacitor is a new energy storage device between supercapacitors and lithium ion secondary batteries, which has both electrochemical energy storage and physical energy storage, and has a large power density and a long cycle life. Therefore, the battery-type lithium ion capacitor is expected to be widely used in electric vehicles, smart grids, energy generation systems, aerospace and other fields.

[0003] At present, the battery-type lithium ion capacitor is usually assembled by winding or stacking with lithium cobaltate, lithium manganate or ternary nickel-cobalt-manganese lithium acid as the positive electrode, hard carbon material as the negative electrode, and cellulose diaphragm as the diaphragm. However, the battery-type lithium ion capacitor has some problems in practical application, for example, the hard carbon material (negative electrode) has many micropores and a large specific surface area, and a large amount of lithium ions from the positive electrode will be consumed by the negative electrode during the first charge and discharge, resulting in a decrease in reversible lithium ions and a decrease in the energy density of the battery-type lithium ion capacitor.

[0004] Therefore, it is a technical problem to be solved to explore a battery-type lithium ion capacitor with high energy density. SUMMARY

[0005] The present application provides a battery-type lithium ion capacitor, which has a high energy density.

[0006] The present application also provides an electronic device comprising the above battery-type lithium ion capacitor, which has a high energy density.

[0007] The present application provides a battery-type lithium ion capacitor, which comprises a negative electrode sheet;

[0008] The negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on at least one surface of the negative electrode current collector;

[0009] The negative electrode active layer comprises a negative electrode active material, which comprises hard carbon and graphite, and the mass percentage of graphite in the negative electrode active material is 2-45%.

[0010] The battery-type lithium ion capacitor as described above further comprises a conductive agent, a thickening agent and a binder;

[0011] The mass percentage content of the negative electrode active material in the negative electrode active layer is 85-95%, the mass percentage content of the conductive agent is 1-5%, the mass percentage content of the thickening agent is 1-5%, and the mass percentage content of the binder is 0.5-5%.

[0012] The battery-type lithium ion capacitor as described above, wherein the D50 of the graphite is 7-10 μm; and / or,

[0013] The specific surface area of the graphite is 2-4 m 2 / g.

[0014] The battery-type lithium ion capacitor as described above, wherein the battery-type lithium ion capacitor further comprises a positive electrode sheet, and the positive electrode sheet is arranged opposite to the negative electrode sheet.

[0015] The positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer arranged on at least one surface of the positive electrode current collector.

[0016] The positive electrode active layer comprises a positive electrode active material, activated carbon, a conductive agent and a binder.

[0017] The battery-type lithium ion capacitor as described above, wherein the mass percentage content of the positive electrode active material in the positive electrode active layer is 80-97%, the mass percentage content of the activated carbon is 1-10%, the mass percentage content of the conductive agent is 1-15%, and the mass percentage content of the binder is 1-8%.

[0018] The battery-type lithium ion capacitor as described above, wherein the battery-type lithium ion capacitor further comprises a separator, and the separator is arranged between the positive electrode sheet and the negative electrode sheet.

[0019] The separator is a polyolefin separator.

[0020] The battery-type lithium ion capacitor as described above, wherein the thickness of the separator is 9-20 μm.

[0021] The battery-type lithium ion capacitor as described above, wherein the porosity of the separator is 38-52%.

[0022] The battery-type lithium ion capacitor as described above, wherein the tensile strength of the separator is >1000 kgf / cm 2 .

[0023] The application further provides an electronic device comprising the battery-type lithium ion capacitor.

[0024] The application provides a battery type lithium ion capacitor, the battery type lithium ion capacitor comprising a negative electrode sheet, wherein graphite is added in the negative electrode sheet. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0026] The application provides a battery type lithium ion capacitor, the battery type lithium ion capacitor comprising a negative electrode sheet;

[0027] The negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on at least one surface of the negative electrode current collector.

[0028] The negative electrode active layer comprises a negative electrode active material, and the negative electrode active material comprises hard carbon and graphite, wherein the mass percentage of the graphite in the negative electrode active material is 2-45%.

[0029] In the embodiments of the present application, the negative electrode current collector can be a conventional negative electrode current collector in the art, for example, the material of the negative electrode current collector layer can be one or more of copper foil, foamed nickel and foamed copper.

[0030] It can be understood that the negative electrode active layer can be located on one surface of the negative electrode current collector to form the negative electrode sheet, or the negative electrode active layer can be located on both surfaces of the negative electrode current collector to form the negative electrode sheet.

[0031] The negative electrode active layer comprises a negative electrode active material, and the negative electrode active material comprises hard carbon and graphite, wherein the mass percentage of the graphite in the negative electrode active material is 2-45%.

[0032] The negative active material of the present application comprises hard carbon and graphite. During the first charge-discharge process of the battery, the hard carbon and the graphite with high rate capability can jointly accept lithium ions, reducing the consumption of lithium ions during the first charge-discharge, improving the first charge-discharge efficiency of the battery-type lithium ion capacitor as a whole, reducing the capacity loss, and further improving the overall energy density. Especially when the content of graphite in the negative active material is within the above range, the graphite can better match the hard carbon, fully play the role of graphite and hard carbon, and further improve the discharge capacity, median voltage, first charge-discharge efficiency and energy density of the battery-type lithium ion capacitor.

[0033] The present application does not limit the specific type of graphite, as long as the mass percentage content of graphite in the negative active material meets the limitation of the present application. In some embodiments, the graphite can be artificial graphite or natural graphite. Further, artificial graphite can be preferred.

[0034] In some embodiments, the above negative active layer further comprises a conductive agent, a thickening agent and a binder.

[0035] The above conductive agent, thickening agent and binder can use conventional types in the art, for example, the conductive agent can be selected from one or more of carbon black, acetylene black, graphene; the thickening agent can be selected from one or more of carboxymethyl cellulose, hydroxymethyl cellulose, sodium hydroxymethyl cellulose (CMC); the binder can be selected from one or more of styrene butadiene latex, polyvinyl chloride, polyvinyl pyrrole, carboxylated polyvinyl chloride, epoxy-containing polymer alkane, polyvinyl fluoride, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyvinyl alcohol.

[0036] In the above negative active layer, the mass percentage content of the negative active material is 85-95%, the mass percentage content of the conductive agent is 1-5%, the mass percentage content of the thickening agent is 1-5%, and the mass percentage content of the binder is 0.5-5%.

[0037] When the mass percentage content of the negative active material, the conductive agent, the thickening agent and the binder in the negative active layer is within the above range, the negative active material, the conductive agent, the thickening agent and the binder in the negative active layer can better match, further improving the energy density of the battery-type lithium ion capacitor.

[0038] In a specific embodiment, the D50 of the graphite is 7-10 μm.

[0039] In detail, the D50 of the graphite can be any one of 7 μm, 8 μm, 9 μm, 10 μm and a range formed by any two thereof.

[0040] In the present application, the D50 of the graphite refers to the particle size value corresponding to the volume cumulative distribution percentage of 50% in all the graphite. When the particle size of the graphite satisfies the range described above, the discharge current of the battery-type lithium ion capacitor can be increased, which is beneficial to improve the discharge capacity, the first charge-discharge efficiency, the median voltage and the energy density of the battery-type lithium ion capacitor.

[0041] In a specific embodiment, the specific surface area of the graphite is 2-4 m 2 / g.

[0042] Illustratively, the specific surface area of the graphite described above can be any one of 2 m 2 / g, 3 m 2 / g, 4 m 2 / g and a range consisting of any two thereof.

[0043] When the specific surface area of the graphite satisfies the range described above, the discharge capacity and the median voltage of the battery-type lithium ion capacitor can be improved, thereby realizing the improvement of the energy density thereof and being capable of improving the electrochemical kinetic performance of the graphite.

[0044] Some embodiments of the present application prepare the negative electrode sheet by the following process:

[0045] The hard carbon, the graphite, the conductive agent, the thickening agent, the binder and the deionized water are mixed, and after stirring and dispersion, a negative electrode slurry is prepared. Then, the negative electrode slurry is coated on the negative electrode current collector and dried, and then rolled, baked to obtain a negative electrode sheet comprising a negative electrode active layer.

[0046] Further, the surface density of the negative electrode slurry coated on the negative electrode current collector is 100-200 g / m 2 ; and / or, the temperature of the drying is 80-120℃; and / or, the compaction density of the rolling is 0.8-1.1 g / cm 3 ; and / or, the temperature of the baking is 90-160℃ and the time is 8-36 h.

[0047] In a specific embodiment, the battery-type lithium ion capacitor further comprises a positive electrode sheet, and the positive electrode sheet is arranged opposite to the negative electrode sheet.

[0048] The positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer arranged on at least one surface of the positive electrode current collector.

[0049] The positive electrode active layer comprises a positive electrode active material, an active carbon, a conductive agent and a binder.

[0050] In the embodiments of the present application, the positive electrode current collector can be a conventional positive electrode current collector in the art, for example, comprising one or more of aluminum foil, nickel foil.

[0051] The positive electrode active layer comprises activated carbon, and the activated carbon has high specific surface area and good electrical conductivity, which helps to improve the capacity and electrical conductivity of the electrode, increase the energy storage capacity of the battery-type lithium ion capacitor, increase the discharge current, and thus improve the overall energy density.

[0052] The positive electrode active material, the conductive agent and the binder can be of conventional types in the art, for example, the positive electrode active material can be selected from one or more of lithium iron phosphate, lithium cobaltate, lithium nickel cobalt manganese oxide; the conductive agent can be selected from one or more of conductive carbon black, acetylene black, graphene, ketjen black, carbon fiber; and the binder can be selected from one or more of polyvinylidene fluoride and polytetrafluoroethylene.

[0053] In the positive electrode active layer, the mass percentage of the positive electrode active material is 80-98%, the mass percentage of the activated carbon is 1-10%, the mass percentage of the conductive agent is 0.1-15%, and the mass percentage of the binder is 1-8%.

[0054] When the mass percentages of the positive electrode active material, the activated carbon, the conductive agent and the binder in the positive electrode active layer are within the above ranges, the positive electrode active material, the activated carbon, the conductive agent and the binder in the positive electrode active layer can be better combined, and the energy density of the battery-type lithium ion capacitor can be effectively improved.

[0055] The positive electrode sheet is prepared by the following process in the embodiment of the present application.

[0056] The positive electrode active material, the activated carbon, the conductive agent and the binder are mixed with N-methyl pyrrolidone, and then the mixture is dispersed by stirring to prepare a positive electrode slurry. The positive electrode slurry is then coated on an aluminum foil current collector and dried, and then rolled, baked, to obtain a positive electrode sheet comprising a positive electrode active layer.

[0057] Further, the areal density of the positive electrode slurry coated on the aluminum foil current collector is 150-300 g / m 2 ; and / or, the drying temperature is 90-150℃; and / or, the compaction density of the rolling is 1.9-2.3 g / cm 3 ; and / or, the baking temperature is 90-160℃, and the baking time is 8-36 h.

[0058] In a specific embodiment, the battery-type lithium ion capacitor further comprises a separator between the positive electrode sheet and the negative electrode sheet; the separator is a polyolefin separator.

[0059] The separator is a polyolefin separator, which has a low thickness and a high tensile strength, and is conducive to improving the energy density and service life of the battery-type lithium ion capacitor.

[0060] The polyolefin separator can use polyolefin separator materials commonly used in the art, such as one or more of polyethylene separator (PE), polypropylene separator (PP), polypropylene / polyethylene double-layer composite film (PP / PE), polypropylene / polyethylene / polypropylene three-layer composite film (PP / PE / PP).

[0061] In one embodiment, the thickness of the separator is 9-20 μm.

[0062] The thickness of the separator can be any one of 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, and a range consisting of any two of them.

[0063] When the thickness of the separator is within the above range, more positive and negative electrode sheets can be accommodated in the battery-type lithium ion capacitor during assembly of the lithium ion capacitor electrode core, thereby improving the energy density of the battery-type lithium ion capacitor.

[0064] In one embodiment, the porosity of the separator is 38-52%.

[0065] The porosity of the separator can be any one of 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, and a range consisting of any two of them.

[0066] When the porosity of the separator is within the above range, it is beneficial for the large rate charge and discharge of the battery-type lithium ion capacitor.

[0067] Further, when the tensile strength of the separator is >1000 kgf / cm 2 , the mechanical stability and durability of the separator are enhanced, which is beneficial for prolonging the service life of the battery-type lithium ion capacitor.

[0068] In addition, one or both sides of the separator are coated with one of alumina, PVDF, a mixture of alumina and PVDF, wherein the alumina is beneficial for improving the heat resistance of the separator, and the PVDF is beneficial for improving the adhesion between the separator and the positive and / or negative electrode sheets.

[0069] In the above battery-type lithium ion capacitor, a capacitor housing and a tab are further included.

[0070] The battery-type lithium ion capacitor is prepared by the following process according to an embodiment of the present application:

[0071] For example, the positive electrode sheet, the negative electrode sheet and the separator are stacked in order (the separator is placed between the positive electrode sheet and the negative electrode sheet) to assemble a lithium ion capacitor electrode core, and then the lithium ion capacitor electrode core, a capacitor shell and a tab are assembled and welded, injected, sealed, formed and tested to obtain the above-mentioned battery-type lithium ion capacitor.

[0072] The present application also provides an electronic device comprising the above-mentioned battery-type lithium ion capacitor, which has a higher energy density.

[0073] The scheme of the present application is described in detail below through specific examples.

[0074] The raw materials used in the following examples, unless otherwise specified, can be obtained from commercial channels; the processes used, unless otherwise specified, are conventional processes in the art.

[0075] Example 1

[0076] The battery-type lithium ion capacitor of the present example is prepared by a method comprising the following steps:

[0077] Lithium iron phosphate, activated carbon, acetylene black and polyvinylidene fluoride (PVDF) are added to N-methyl pyrrolidone (NMP) in a mass ratio of 83:7:5:5, and after stirring and dispersion, a positive electrode slurry is obtained, which is then coated on an 18 μm aluminum foil current collector with a 2 μm conductive coating and dried, and then rolled and baked to obtain a positive electrode sheet comprising a positive electrode active layer;

[0078] The areal density of the above-mentioned positive electrode slurry coated on the aluminum foil current collector is 205 g / m 2 ; the drying temperature is 130°C; the compaction density of the positive electrode active layer is 2.0 g / cm 3 ; the baking temperature is 110°C and the time is 12 h.

[0079] Hard carbon, artificial graphite, acetylene black, sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) are added to deionized water in a mass ratio of 72:20:3:2:3, and after dispersion, a negative electrode slurry is obtained, which is then coated on a 10 μm copper foil current collector and dried, and then rolled and baked to obtain a negative electrode sheet comprising a negative electrode active layer;

[0080] The D50 of the above-mentioned artificial graphite is 9.0 μm, and the specific surface area of the artificial graphite is 2.0 m 2 / g;

[0081] The areal density of the above-mentioned negative electrode slurry coated on the copper foil current collector is 150 g / m 2 ; the drying temperature is 100°C; the compaction density of the negative electrode active layer is 1.1 g / cm 3; the drying temperature is 130°C; the compaction density of the positive active layer is 2.0 g / cm

[0082] A 16-μm polyethylene separator is used; the porosity of the polyethylene separator is 46%, one side of the polyethylene separator is coated with 2-μm alumina (Al2O3), and the tensile strength of the polyethylene separator is 1200 Kgf / cm 2 .

[0083] The positive electrode sheet, the negative electrode sheet, and the polyethylene separator are stacked in order (the polyethylene separator is placed between the positive electrode sheet and the negative electrode sheet) to assemble a lithium ion capacitor electrode core, and then the lithium ion capacitor electrode core, a capacitor case, and a tab are assembled and welded, liquid injection, sealing, formation, and capacity measurement are performed to obtain the battery-type lithium ion capacitor.

[0084] Example 2

[0085] The battery-type lithium ion capacitor of the present example is prepared by a method comprising the following steps:

[0086] Lithium iron phosphate, activated carbon, acetylene black, and polyvinylidene fluoride (PVDF) are added to N-methyl pyrrolidone (NMP) in a mass ratio of 85:6:4:5, and a positive electrode slurry is obtained after stirring and dispersion, and then the positive electrode slurry is coated on an 18-μm aluminum foil current collector with a 2-μm conductive coating and dried, and then rolled and baked to obtain a positive electrode sheet comprising a positive active layer;

[0087] The areal density of the positive electrode slurry coated on the aluminum foil current collector is 200 g / m 2 ; the drying temperature is 130°C; the compaction density of the positive active layer is 2.0 g / cm 3 ; the baking temperature is 110°C, and the baking time is 12 h.

[0088] Hard carbon, artificial graphite, acetylene black, sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) are added to deionized water in a mass ratio of 82:10:3:2:3, and a negative electrode slurry is obtained after stirring and dispersion, and then the negative electrode slurry is coated on a 10-μm copper foil current collector and dried, and then rolled and baked to obtain a negative electrode sheet comprising a negative active layer;

[0089] The D50 of the artificial graphite is 9.0 μm, and the specific surface area of the artificial graphite is 2.0 m 2 / g;

[0090] The areal density of the negative electrode slurry coated on the copper foil current collector is 150 g / m 2 ; the drying temperature is 100°C; the compaction density of the negative active layer is 1.0 g / cm 3 ; the baking temperature is 110°C, and the baking time is 12 h.

[0091] A 12-μm polyethylene separator was used; the porosity of the polyethylene separator was 46%, and one side of the polyethylene separator was coated with 2-μm alumina (AI2O3) having a tensile strength of 1200 Kgf / cm 2 .

[0092] The positive electrode sheet, the negative electrode sheet, and the polyethylene separator were sequentially stacked (the separator was placed between the positive electrode sheet and the negative electrode sheet) to assemble a lithium ion capacitor electrode core, and then the lithium ion capacitor electrode core, a capacitor case, and a tab were assembled and welded, liquid injected, sealed, formed, and measured to obtain the above-described battery-type lithium ion capacitor.

[0093] Example 3

[0094] The battery-type lithium ion capacitor of the present example was prepared by a method including the following steps:

[0095] Lithium iron phosphate, activated carbon, acetylene black, and polyvinylidene fluoride (PVDF) were added to N-methylpyrrolidone (NMP) in a mass ratio of 85:6:4:5, and a positive electrode slurry was obtained after stirring and dispersion. The positive electrode slurry was then coated on a 16-μm aluminum foil current collector having a 2-μm conductive coating and dried, and then roll-pressed and baked to obtain a positive electrode sheet including a positive electrode active layer.

[0096] The areal density of the positive electrode slurry coated on the aluminum foil current collector was 205 g / m 2 ; the drying temperature was 130°C; the compaction density of the positive electrode active layer was 2.1 g / cm 3 ; the baking temperature was 110°C, and the baking time was 12 h.

[0097] Hard carbon, artificial graphite, acetylene black, sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) were added to deionized water in a mass ratio of 87:5:3:2:3, and a negative electrode slurry was obtained after high-speed stirring and dispersion to adjust the viscosity. The negative electrode slurry was then coated on a 10-μm copper foil current collector and dried, and then roll-pressed and baked to obtain a negative electrode sheet including a negative electrode active layer.

[0098] The D50 of the artificial graphite was 9.0 μm, and the specific surface area of the artificial graphite was 2.0 m 2 / g;

[0099] The areal density of the negative electrode slurry coated on the copper foil current collector was 150 g / m 2 ; the drying temperature was 100°C; the compaction density of the negative electrode active layer was 0.95 g / cm 3 ; the baking temperature was 110°C, and the baking time was 12 h.

[0100] A 12-μm polyethylene separator was used; the porosity of the polyethylene separator was 46%, and the tensile strength of one side of the polyethylene separator coated with 2-μm alumina (Al2O3) was 1200 Kgf / cm 2 .

[0101] The positive electrode sheet, the negative electrode sheet, and the polyethylene separator were stacked in order (the separator was placed between the positive electrode sheet and the negative electrode sheet) to assemble a lithium ion capacitor electrode core, and then the lithium ion capacitor electrode core, a capacitor case, and a tab were assembled and welded, liquid was injected, sealed, formed, and measured to obtain the above-described battery-type lithium ion capacitor.

[0102] Example 4

[0103] The battery-type lithium ion capacitor provided in this example was prepared in the same manner as in Example 1, except that:

[0104] The D50 of the artificial graphite was 8.0 μm.

[0105] Example 5

[0106] The battery-type lithium ion capacitor provided in this example was prepared in the same manner as in Example 1, except that:

[0107] The specific surface area of the artificial graphite was 3.5 m 2 / g.

[0108] Example 6

[0109] The battery-type lithium ion capacitor provided in this example was prepared in the same manner as in Example 1, except that:

[0110] A 25-μm polyethylene separator was used.

[0111] Example 7

[0112] The battery-type lithium ion capacitor provided in this example was prepared in the same manner as in Example 1, except that:

[0113] A 7-μm polyethylene separator was used.

[0114] Example 8

[0115] The battery-type lithium ion capacitor provided in this example was prepared in the same manner as in Example 1, except that:

[0116] The porosity of the polyethylene separator was 55%.

[0117] Example 9

[0118] The battery-type lithium ion capacitor provided in this example was prepared in the same manner as in Example 1, except that:

[0119] The porosity of the polyethylene separator was 35%.

[0120] Comparative Example 1

[0121] The battery-type lithium ion capacitor of the present comparative example was prepared by a method comprising the following steps:

[0122] Lithium iron phosphate, activated carbon, acetylene black and polyvinylidene fluoride (PVDF) were added into N-methyl pyrrolidone (NMP) in a mass ratio of 85:6:4:5, and after being dispersed by stirring, a positive electrode slurry was obtained. Then, the positive electrode slurry was coated on an 18 μm aluminum foil current collector with a 2 μm conductive coating and dried, and then rolled and baked to obtain a positive electrode sheet.

[0123] The areal density of the above positive electrode slurry coated on the aluminum foil current collector was 200 g / m 2 ; the drying temperature was 130°C; the compaction density of rolling was 2.0 g / cm 3 ; the baking temperature was 110°C and the time was 12 h.

[0124] Hard carbon, acetylene black, sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) were added into deionized water in a mass ratio of 92:3:2:3, and after being dispersed by stirring, a negative electrode slurry was obtained. Then, the negative electrode slurry was coated on a 10 μm copper foil current collector and dried, and then rolled and baked to obtain a negative electrode sheet.

[0125] The areal density of the above negative electrode slurry coated on the copper foil current collector was 150 g / m 2 ; the drying temperature was 100°C; the compaction density of rolling was 1.1 g / cm 3 ; the baking temperature was 110°C and the time was 12 h.

[0126] A 16 μm polyethylene separator was used; the porosity of the above polyethylene separator was 46%, one side of which was coated with 2 μm aluminum oxide (Al2O3), and the tensile strength thereof was 1200 Kgf / cm 2 .

[0127] The positive electrode sheet, the negative electrode sheet and the polyethylene separator were sequentially stacked (the separator was placed between the positive electrode sheet and the negative electrode sheet) to assemble a lithium ion capacitor core, and then the lithium ion capacitor core, a capacitor shell and a tab were assembled and welded, liquid injection, sealing, formation and capacity distribution were performed to obtain the above battery-type lithium ion capacitor.

[0128] Comparative Example 2

[0129] The battery-type lithium ion capacitor of the present comparative example was prepared in accordance with Example 1, except that:

[0130] Hard carbon, conductive agent, thickening agent and styrene-butadiene rubber (SBR) were added into deionized water in a mass ratio of 92:3:2:3.

[0131] Comparative Example 3

[0132] The preparation of the battery-type lithium ion capacitor provided by the present comparative example is consistent with that of Example 1, except that:

[0133] Hard carbon, artificial graphite, conductive agent, thickening agent and styrene-butadiene rubber (SBR) were added to deionized water in a mass ratio of 42:50:3:2:3.

[0134] Table 1: Mass percentage of hard carbon, mass percentage of artificial graphite, D50 of artificial graphite and specific surface area of artificial graphite of each example and comparative example

[0135] Table 2: Thickness, porosity and tensile strength of polyethylene separator of each example and comparative example

[0136] Performance test

[0137] The battery-type lithium ion capacitors of the examples and comparative examples were subjected to the following performance tests according to the test procedures of Table 3, and the test results are shown in Table 4.

[0138] Table 3: Test procedures

[0139] Among them, the capacity of the battery-type lithium ion capacitor at the 8th step test is recorded as the discharge capacity, the voltage when discharged to 50% is the median voltage, the ratio of discharge energy to mass is the energy density, and the ratio of the capacity at the 8th step test to the sum of the capacities at the 2nd, 4th and 6th step tests is recorded as the first charge-discharge efficiency.

[0140] Table 4: Test results

[0141] As can be seen from Table 4, the battery-type lithium ion capacitor according to the present application can effectively improve the discharge capacity, median voltage, first charge-discharge efficiency and energy density of the battery-type lithium ion capacitor.

[0142] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery-type lithium ion capacitor, characterized by, The battery-type lithium ion capacitor comprises a negative electrode sheet; The negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on at least one surface of the negative electrode current collector; The negative electrode active layer comprises a negative electrode active material, the negative electrode active material comprises hard carbon and graphite, and the mass percentage of the graphite in the negative electrode active material is 2-45%.

2. The battery-type lithium-ion capacitor according to claim 1, wherein The negative electrode active layer further comprises a conductive agent, a thickening agent and a binder; In the negative electrode active layer, the mass percentage of the negative electrode active material is 85-95%, the mass percentage of the conductive agent is 1-5%, the mass percentage of the thickening agent is 1-5%, and the mass percentage of the binder is 0.5-5%.

3. The battery-type lithium-ion capacitor according to claim 2, wherein The D50 of the graphite is 7-10 μm; and / or, The specific surface area of the graphite is 2-4 m 2 / g.

4. The battery-type lithium-ion capacitor of claim 1, wherein, The battery-type lithium ion capacitor further comprises a positive electrode sheet, the positive electrode sheet is arranged opposite to the negative electrode sheet; The positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer arranged on at least one surface of the positive electrode current collector; The positive electrode active layer comprises a positive electrode active material, activated carbon, a conductive agent and a binder.

5. The battery-type lithium-ion capacitor of claim 4, wherein, In the positive electrode active layer, the mass percentage of the positive electrode active material is 80-97%, the mass percentage of the activated carbon is 1-10%, the mass percentage of the conductive agent is 1-15%, and the mass percentage of the binder is 1-8%.

6. The battery-type lithium-ion capacitor according to claim 4 or 5, characterized by The battery-type lithium ion capacitor further comprises a separator, the separator is arranged between the positive electrode sheet and the negative electrode sheet; The separator is a polyolefin separator.

7. The battery-type lithium-ion capacitor of claim 6, wherein, The thickness of the separator is 9-20 μm.

8. The battery-type lithium-ion capacitor of claim 6, wherein, The porosity of the separator is 38-52%.

9. The battery-type lithium-ion capacitor of claim 6, wherein, Tensile strength of the membrane > 1000 kgf / cm 2 .

10. An electronic device, comprising: The battery-type lithium ion capacitor comprises the battery-type lithium ion capacitor according to any one of claims 1-9.

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