Positive electrode slurry containing metal wire, negative electrode slurry, positive electrode plate without current collector, positive electrode plate and battery

Abstract

The invention provides a metal wire-containing positive electrode slurry, a metal wire-containing negative electrode slurry, a current collector-free positive electrode plate, a current collector-free positive electrode plate and a battery. The toughness of the active material layer is improved by adding trace metal wires into the positive / negative electrode slurry, and the problem of insufficient electronic conductivity caused by the absence of a current collector is improved; the positive electrode / negative electrode slurry containing the metal wire is coated on the diaphragm, so that the manufacturability of the active material layer is further improved, and the current collector-free battery can be industrially produced and manufactured; the content of the added metal wires is 0.02-2% of the total solid content, and the energy density of the whole battery is higher than that of a traditional battery; due to the addition of the metal wire, the resistivity of the diaphragm of the positive pole piece is reduced from 5-100 omega.cm to 0.01-3 omega.cm, the potential difference of the pole piece in the thickness direction is smaller in the charging and discharging process of the battery, the thickness of an active material layer can be increased under the same performance, and the energy density of the battery can be further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a positive electrode slurry containing metal wires, a negative electrode slurry, a positive electrode sheet without a current collector, a positive electrode sheet and a battery. Background Art

[0002] In recent years, with economic development and social progress, lithium-ion batteries and sodium-ion batteries have been used more and more widely. In particular, the pursuit of energy density in the field of mobile devices has made commercial chemical batteries increasingly close to the limit of energy density, while new high-energy-density batteries are still far from commercial applications. This requires improving the energy density of lithium-ion batteries and sodium-ion batteries from the perspective of battery structure. Increasing the thickness of the pole piece and using a self-supporting pole piece without a current collector are the most common methods to increase the energy density of batteries.

[0003] However, increasing the thickness of the electrode will make the electron and ion transmission path longer. The traditional self-supporting electrode without current collector will aggravate the ohmic polarization. Moreover, the self-supporting electrode without current collector is usually brittle and lacks toughness, which poses great difficulties in the field of industrial manufacturing.

[0004] Based on the defects of the current collector-free batteries, it is necessary to improve them. Summary of the invention

[0005] The present invention provides a positive electrode slurry containing metal wire, a negative electrode slurry, a positive electrode sheet without a current collector, a positive electrode sheet and a battery, so as to solve or at least partially solve the defects existing in the prior art.

[0006] In a first aspect, the present invention provides a positive electrode slurry containing metal wires, comprising positive electrode slurry and metal wires.

[0007] Preferably, the metal wire includes at least one of a copper metal wire, an aluminum metal wire, a nickel metal wire, a silver metal wire, and a gold metal wire;

[0008] And / or, the diameter of the metal wire is 0.1 to 200 μm, preferably, the diameter of the metal wire is 2 to 20 μm;

[0009] And / or, the aspect ratio of the metal wire is 20-5000, preferably, the aspect ratio of the metal wire is 200-1000.

[0010] Preferably, the positive electrode slurry comprises a positive electrode active material, a conductive agent, a positive electrode binder, and a positive electrode solvent, and the mass of the metal wire is 0.02 to 2% of the mass of the total solid matter in the positive electrode slurry containing the metal wire;

[0011] Preferably, the mass of the metal wire is 0.1-0.5% of the mass of the total solid matter in the positive electrode slurry.

[0012] Preferably, the positive electrode active material includes at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, sodium nickel cobalt manganese oxide, composite sodium iron pyrophosphate, sodium ferrous sulfate, and sodium vanadium phosphate;

[0013] and / or, the conductive agent comprises at least one of conductive carbon black, conductive graphite, carbon nanotubes, graphene and nano-carbon fibers;

[0014] And / or, the positive electrode binder includes at least one of PVDF, PTFE, CMC, SBR, PAN, and PAA;

[0015] And / or, the cathode solvent includes at least one of NMP and water;

[0016] And / or, the mass ratio of the positive electrode active material, the conductive agent, the positive electrode binder, the positive electrode solvent, and the metal wire in the positive electrode slurry containing the metal wire is (90-98.6):(0.01-5):(0.1-5):(40-100):(0.02-2).

[0017] In a second aspect, the present invention further provides a negative electrode slurry containing metal wires, characterized in that it comprises negative electrode slurry and metal wires.

[0018] Preferably, the metal wire includes at least one of a copper metal wire, an aluminum metal wire, a nickel metal wire, a silver metal wire, and a gold metal wire;

[0019] And / or, the diameter of the metal wire is 0.1 to 200 μm, preferably, the diameter of the metal wire is 2 to 20 μm;

[0020] And / or, the aspect ratio of the metal wire is 20-5000, preferably, the aspect ratio of the metal wire is 200-1000.

[0021] Preferably, the negative electrode slurry comprises a negative electrode active material, a conductive agent, a thickener, a negative electrode binder and a negative electrode solvent, and the mass of the metal wire is 0.02-2% of the mass of the total solid matter in the negative electrode slurry containing the metal wire;

[0022] Preferably, the mass of the metal wire is 0.1-0.5% of the mass of the total solid matter in the negative electrode slurry.

[0023] Preferably, the negative electrode active material includes at least one of graphite, soft carbon, hard carbon, silicon-based compounds, titanium-based compounds, and phosphorus-based compounds;

[0024] and / or, the conductive agent comprises at least one of conductive carbon black, conductive graphite, carbon nanotubes, graphene and nano-carbon fibers;

[0025] And / or, the thickener comprises CMC;

[0026] And / or, the negative electrode binder includes one of SBR, PVDF, PAN, PI, and PAA;

[0027] And / or, the negative electrode solvent includes at least one of water and NMP;

[0028] And / or, the mass ratio of the negative electrode active material, the conductive agent, the thickener, the negative electrode binder, the negative electrode solvent, and the metal wire in the negative electrode slurry containing the metal wire is (90-98.6):(0.01-5):(0.2-3):(0.2-5):(40-130):(0.02-2).

[0029] In a third aspect, the present invention further provides a positive electrode sheet without a current collector, comprising:

[0030] A diaphragm, wherein a positive electrode active material layer is provided on the surface of the diaphragm, wherein the positive electrode active material layer is obtained by coating the positive electrode slurry containing the metal wire on the surface of the diaphragm and drying;

[0031] The positive electrode tab is located on one side of the positive electrode active material layer.

[0032] In a fourth aspect, the present invention further provides a negative electrode sheet without a current collector, comprising:

[0033] A diaphragm, wherein a negative electrode active material layer is provided on the surface of the diaphragm, wherein the negative electrode active material layer is obtained by coating the negative electrode slurry containing the metal wire on the surface of the diaphragm and drying;

[0034] The negative electrode tab is located on one side of the negative electrode active material layer.

[0035] Preferably, the diaphragm includes at least one of a PE diaphragm, a PP diaphragm, a PP / PE diaphragm, a PP / PE / PP diaphragm, a PE diaphragm with a heat-resistant coating, a PP diaphragm with a heat-resistant coating, a PI diaphragm, a PA diaphragm, and a cellulose diaphragm;

[0036] The thickness of the heat-resistant coating is 1 to 3 μm, and the heat-resistant coating includes but is not limited to an aluminum oxide coating and a boehmite coating;

[0037] The thickness of the diaphragm is 3 to 20 μm;

[0038] The positive electrode tab comprises at least one of aluminum foil, aluminum sheet, foamed aluminum, and aluminum wire;

[0039] The negative electrode tab includes at least one of nickel foil, nickel sheet, nickel wire, foamed nickel, copper foil, copper sheet, copper wire, foamed copper, aluminum foil, aluminum sheet, foamed aluminum, and aluminum wire.

[0040] In a fifth aspect, the present invention further provides a battery without a current collector, comprising at least one positive electrode sheet without a current collector and at least one negative electrode sheet without a current collector;

[0041] The positive electrode sheets without current collectors and the negative electrode sheets without current collectors are alternately stacked.

[0042] The positive electrode slurry, negative electrode slurry, positive electrode sheet without current collector, positive electrode sheet and battery of the present invention containing metal wire have the following beneficial effects compared with the prior art:

[0043] 1. The positive electrode slurry / negative electrode slurry containing metal wires of the present invention increases the toughness of the active material layer by adding a trace amount of metal wires to the positive electrode slurry / negative electrode slurry, and improves the problem of insufficient electronic conductivity caused by the absence of a current collector; the present invention further increases the manufacturability of the active material layer by coating the positive electrode slurry / negative electrode slurry containing metal wires on the separator, so that the current collector-free battery can be industrially produced and manufactured;

[0044] 2. Compared with the traditional self-supporting pole piece without current collector, the positive pole piece / negative pole piece without current collector of the present invention adopts the positive and negative pole diaphragm integrated component coated with positive electrode slurry / negative electrode slurry on the diaphragm, which reduces the components of winding or lamination process and is more conducive to the control of "Overhang"; at the same time, the positive and negative pole diaphragm integrated component makes the contact between the diaphragm and the active material closer and not easy to separate, thereby improving the cycle performance of the battery; the metal wire added in the present invention is usually only 0.02-2% of the total solid content, and the metal current collector foil is eliminated. Under the same performance, the energy density of the overall battery is higher than that of the battery made of traditional pole pieces; and because the active material is attached to the flexible diaphragm, the pole piece has good flexibility and can form a continuous winding, which is convenient for batch and continuous production; the thickness of the traditional pole piece, the positive current collector (usually aluminum foil) The thickness of the negative electrode current collector is usually 8-15μm, the thickness of the negative electrode current collector is 4.5-10μm, and the volume of the current collector accounts for 2-10% of the total electrode volume; the metal wire added to the positive electrode plate / negative electrode plate without current collector of the present invention is usually only 0.02-2% of the total solid content, and the energy density of the overall battery is higher than that of the battery made of traditional electrodes; due to the addition of metal wire, the resistivity of the positive electrode plate is reduced from 5-100Ω·cm to 0.01-3Ω·cm. During the charge and discharge process of the battery, the potential difference of the electrode plate in the thickness direction is smaller. Under the same performance, the thickness of the active material layer can be increased, which is conducive to further improving the energy density of the battery; the present invention directly attaches the positive electrode slurry / negative electrode slurry containing metal wire to the diaphragm, so that the positive electrode / negative electrode active material and the diaphragm are more closely combined, the internal resistance of the battery cell is reduced, and the cycle life of the battery cell is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 It is a schematic structural diagram of a positive electrode sheet without a current collector of the present invention;

[0047] Figure 2 It is a schematic structural diagram of a negative electrode sheet without a current collector of the present invention;

[0048] Figure 3 It is a schematic diagram of the alternating stacking arrangement of the positive electrode sheet without current collector and the negative electrode sheet without current collector of the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0051] The following are described in detail. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and simplicity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any quoted numbers (fractions or integers) within the indicated range.

[0052] The invention provides a positive electrode slurry containing metal wires, comprising positive electrode slurry and metal wires.

[0053] In some embodiments, the metal wire in the positive electrode slurry containing metal wire includes at least one of copper metal wire, aluminum metal wire, nickel metal wire, silver metal wire, and gold metal wire. Preferably, the metal wire is aluminum metal wire.

[0054] In some embodiments, the diameter of the metal wire is 0.1-200 μm, and preferably, the diameter of the metal wire is 2-20 μm.

[0055] In some embodiments, the aspect ratio of the metal wire is 20 to 5000. Preferably, the aspect ratio of the metal wire is 200 to 1000. Specifically, the aspect ratio refers to the ratio of the length to the diameter of the metal wire.

[0056] In some embodiments, the positive electrode slurry includes a positive electrode active material, a conductive agent, a positive electrode binder, and a positive electrode solvent, and the mass of the metal wire is 0.02-2% of the mass of the total solid matter in the positive electrode slurry containing the metal wire; preferably, the mass of the metal wire is 0.1-0.5% of the mass of the total solid matter in the positive electrode slurry. Specifically, the total solid matter in the positive electrode slurry containing the metal wire includes substances other than the positive electrode solvent, that is, the total solid matter in the positive electrode slurry containing the metal wire includes the positive electrode active material, the conductive agent, the positive electrode binder and the metal wire, wherein the mass of the metal wire is 0.02-2% of the mass of the total solid matter.

[0057] In some embodiments, the specific material used for the positive electrode active material is not limited, and the positive electrode active material commonly used in lithium-ion batteries can be used. For example, the positive electrode active material includes but is not limited to at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, sodium nickel cobalt manganese oxide, composite sodium iron pyrophosphate, sodium ferrous sulfate, sodium vanadium phosphate, etc.

[0058] In some embodiments, the specific material used for the conductive agent is not limited, and a conductive agent commonly used in lithium-ion batteries can be used. For example, the conductive agent includes but is not limited to at least one of conductive carbon black, conductive graphite, carbon nanotubes, and nano-carbon fibers;

[0059] In some embodiments, the specific material used for the positive electrode binder is not limited, and a common positive electrode binder for lithium-ion batteries can be used. For example, the positive electrode binder includes but is not limited to at least one of PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), CMC (sodium carboxymethyl cellulose), SBR (styrene butadiene rubber latex), PAN (polyacrylonitrile), PAA (polyacrylic acid), etc.

[0060] In some embodiments, the specific material used for the positive electrode solvent is not limited, and a common positive electrode solvent for lithium-ion batteries is used. For example, the positive electrode solvent includes but is not limited to at least one of NMP (N-methylpyrrolidone), water, etc.

[0061] In some embodiments, the mass ratio of the positive electrode active material, conductive agent, positive electrode binder, and positive electrode solvent in the positive electrode slurry containing metal wire is determined according to actual conditions. For example, the mass ratio of the positive electrode active material, conductive agent, positive electrode binder, and positive electrode solvent is (90-98.6):(0.01-5):(0.1-5):(40-100); the mass of the metal wire is 0.02-2% of the sum of the mass of the positive electrode active material, conductive agent, binder, and metal wire, preferably 0.1-0.5%.

[0062] In some embodiments, the mass ratio of the positive electrode active material, the conductive agent, the positive electrode binder, the positive electrode solvent, and the metal wire in the positive electrode slurry containing the metal wire is (90-98.6):(0.01-5):(0.1-5):(40-100):(0.02-2).

[0063] The preparation method of the positive electrode slurry containing metal wires is as follows: adding the positive electrode active material, conductive agent, binder and positive electrode solvent in the positive electrode slurry into a mixer and stirring and dispersing them, then adding the metal wires and continuing stirring and dispersing them to obtain the positive electrode slurry containing metal wires.

[0064] Based on the same inventive concept, the present invention also provides a negative electrode slurry containing metal wires, including negative electrode slurry and metal wires.

[0065] In some embodiments, the metal wire in the negative electrode slurry containing metal wire includes at least one of copper metal wire, aluminum metal wire, nickel metal wire, silver metal wire, and gold metal wire.

[0066] In some embodiments, the diameter of the metal wire is 0.1-200 μm, and preferably, the diameter of the metal wire is 2-20 μm.

[0067] In some embodiments, the aspect ratio of the metal wire is 20-5000. Preferably, the aspect ratio of the metal wire is 200-1000.

[0068] In some embodiments, the negative electrode slurry includes a negative electrode active material, a conductive agent, a thickener, a negative electrode binder, and a negative electrode solvent, and the mass of the metal wire is 0.02-2% of the mass of the total solid matter in the negative electrode slurry containing the metal wire; preferably, the mass of the metal wire is 0.1-0.5% of the mass of the total solid matter in the negative electrode slurry. Specifically, the total solid matter in the negative electrode slurry containing the metal wire includes substances other than the negative electrode solvent, that is, the total solid matter in the negative electrode slurry containing the metal wire includes the negative electrode active material, the conductive agent, the thickener, the negative electrode binder, and the metal wire, wherein the mass of the metal wire is 0.02-2% of the mass of the total solid matter.

[0069] In some embodiments, the specific material used for the negative electrode active material is not limited, and the common negative electrode active material for lithium-ion batteries can be used. For example, the negative electrode active material includes at least one of graphite, soft carbon, hard carbon, silicon-based compounds, titanium-based compounds, phosphorus-based compounds, etc.

[0070] In some embodiments, the specific material used for the conductive agent is not limited, and a conductive agent commonly used in lithium-ion batteries can be used. For example, the conductive agent includes but is not limited to at least one of conductive carbon black (Super-P), conductive graphite, carbon nanotubes and nano-carbon fibers.

[0071] In some embodiments, the specific material used for the thickener in the negative electrode slurry is not limited, and a thickener commonly used in lithium-ion batteries can be used, for example, the thickener can be CMC.

[0072] In some embodiments, the specific material used for the negative electrode solvent is not limited, and a common negative electrode solvent for lithium-ion batteries is used. For example, the negative electrode solvent includes but is not limited to at least one of NMP, water, etc.

[0073] In some embodiments, the specific material used for the negative electrode binder is not limited, and a common negative electrode binder for lithium-ion batteries can be used. For example, the negative electrode binder includes but is not limited to at least one of SBR, PVDF, PAN, PI (polyimide), PAA, etc.

[0074] In some embodiments, the mass ratio of the negative electrode active material, conductive agent, thickener, negative electrode binder and negative electrode solvent in the negative electrode slurry containing metal wire is determined according to actual conditions. For example, the mass ratio of the negative electrode active material, conductive agent, thickener, negative electrode binder and negative electrode solvent is (90-98.6):(0.01-5):(0.2-3):(0.2-5):(40-130). The mass of the metal wire is 0.02-2% of the sum of the masses of the negative electrode active material, conductive agent, thickener, negative electrode binder and metal wire, and preferably 0.1-0.5%.

[0075] In some embodiments, the mass ratio of the negative electrode active material, the conductive agent, the thickener, the negative electrode binder, the negative electrode solvent, and the metal wire in the negative electrode slurry containing the metal wire is (90-98.6):(0.01-5):(0.2-3):(0.2-5):(40-130):(0.02-2).

[0076] The preparation method of the negative electrode slurry containing metal wires is as follows: adding the negative electrode active material, conductive agent, thickener and negative electrode solvent in the negative electrode slurry into a mixer and stirring and dispersing them, then adding the metal wires and continuing stirring and dispersing them to obtain the negative electrode slurry containing metal wires.

[0077] The positive electrode slurry / negative electrode slurry containing metal wires of the present invention increases the toughness of the active material layer by adding a trace amount of metal wires into the positive electrode slurry / negative electrode slurry, and improves the problem of insufficient electronic conductivity caused by the absence of a current collector.

[0078] Based on the same inventive concept, the present invention also provides a positive electrode sheet without a current collector, comprising:

[0079] A separator, the surface of which is provided with a positive electrode active material layer, wherein the positive electrode active material layer is obtained by coating the positive electrode slurry containing the metal wire on the surface of the separator and drying it;

[0080] The positive electrode tab is located on one side of the positive electrode active material layer.

[0081] Specifically, the preparation method of the above-mentioned current collector-free positive electrode sheet is: after coating the positive electrode slurry containing metal wire on the surface of the diaphragm, placing the positive electrode tab on the edge of the slurry, and then placing it in a drying oven to dry and volatilize the positive electrode solvent to obtain a positive electrode active material layer.

[0082] In some embodiments, the positive electrode slurry is coated on the surface of the separator, and the surface density is 0.5-2.5 g / 100 cm 2 , 100cm 2 The diaphragm contains 0.5-2.5g of positive electrode slurry (calculated by weight after drying), that is, after the positive electrode slurry is coated on the surface of the diaphragm, a positive electrode ear is placed on the edge of the slurry, and then placed in a drying oven to dry and evaporate the positive electrode solvent, the surface density of the positive electrode slurry is 0.5-2.5g / 100cm 2 .

[0083] Based on the same inventive concept, the present invention also provides a negative electrode sheet without a current collector, comprising:

[0084] A diaphragm, a negative electrode active material layer is provided on the surface of the diaphragm, wherein the negative electrode active material layer is obtained by coating a negative electrode slurry containing metal wires on the surface of the diaphragm and drying;

[0085] The negative electrode tab is located on one side of the negative electrode active material layer.

[0086] Specifically, the preparation method of the above-mentioned current collector-free negative electrode sheet is: after coating the negative electrode slurry containing metal wire on the surface of the diaphragm, placing the negative electrode tab on the edge of the slurry, and then placing it in a drying oven to dry and volatilize the positive electrode solvent to obtain the positive electrode active material layer.

[0087] In some embodiments, the negative electrode slurry is coated on the surface of the separator, and the surface density is 0.2-1.5 g / 100 cm 2 , 100cm 2 The diaphragm contains 0.2-1.5g of negative electrode slurry (calculated by weight after drying), that is, after the negative electrode slurry containing metal wire is coated on the surface of the diaphragm, the negative electrode tab is placed on the edge of the slurry, and then it is placed in a drying oven to dry and allow the positive electrode solvent to evaporate. The surface density of the negative electrode slurry is 0.2-1.5g / 100cm 2 .

[0088] In some embodiments, the specific material used for the diaphragm is not limited, and a diaphragm commonly used in lithium-ion batteries or sodium-ion batteries can be used. For example, the diaphragm includes at least one of a PE diaphragm (i.e., a polyethylene diaphragm), a PP diaphragm (i.e., a polypropylene diaphragm), a PP / PE diaphragm (i.e., a polypropylene / polyethylene double-layer diaphragm), a PP / PE / PP diaphragm (i.e., a polypropylene / polyethylene / polypropylene three-layer diaphragm), a PE diaphragm containing a heat-resistant coating, a PP diaphragm containing a heat-resistant coating, a PI diaphragm, a PA diaphragm, a cellulose diaphragm, and the like.

[0089] In some embodiments, the thickness of the separator is 3-20 μm.

[0090] In some embodiments, the thickness of the heat-resistant coating is 1 to 3 μm, and the heat-resistant coating includes but is not limited to at least one of an aluminum oxide coating, a boehmite coating, and the like.

[0091] In some embodiments, the positive electrode tab includes at least one of aluminum foil, aluminum sheet, foamed aluminum, and aluminum wire;

[0092] In some embodiments, the negative electrode tab includes at least one of nickel foil, nickel sheet, nickel wire, nickel foam, copper foil, copper sheet, copper wire, copper foam, aluminum foil, aluminum sheet, aluminum foam, and aluminum wire.

[0093] In some embodiments, Figure 1 As shown, it is a schematic diagram of the structure of the positive electrode sheet without current collector of the present invention, Figure 1 The top view and the side view are of a positive electrode sheet without a current collector. The positive electrode sheet without a current collector includes a separator 1 , a positive electrode active material layer 2 and a positive electrode tab 3 .

[0094] In some embodiments, Figure 2As shown, it is a schematic diagram of the structure of the negative electrode sheet without current collector of the present invention, Figure 2 The top view and the side view are of a negative electrode sheet without a current collector. The negative electrode sheet without a current collector includes a separator 1 , a negative electrode active material layer 4 and a negative electrode tab 5 .

[0095] The present invention further increases the manufacturability of the active material layer by coating the positive electrode slurry / negative electrode slurry containing metal wires on the separator, so that the current collector-free battery can be industrially produced and manufactured.

[0096] Compared with the traditional self-supporting pole piece without current collector, the present invention adopts the positive and negative electrode diaphragm integrated component coated with positive electrode slurry / negative electrode slurry on the diaphragm, which reduces the components of winding or lamination process and is more conducive to the control of "overhang"; at the same time, the positive and negative electrode diaphragm integrated component makes the contact between the diaphragm and the active material closer and not easy to separate, thereby improving the cycle performance of the battery; the metal wire added in the present invention is usually only 0.02-2% of the total solid content, and the metal current collector foil is eliminated. Under the same performance, the energy density of the overall battery is higher than that of the battery made of traditional pole pieces; due to the addition of metal wire, the diaphragm resistivity of the pole piece is reduced from 5-100Ω·cm to 0.01-3Ω·cm. During the charge and discharge process of the battery, the potential difference of the pole piece in the thickness direction is smaller. Under the same performance, the thickness of the active material layer can be increased, which is conducive to further improving the energy density of the battery.

[0097] Since the active material is attached to the flexible diaphragm, the pole piece has good flexibility and can be wound continuously, which is convenient for batch and continuous production. In the conventional pole piece, the thickness of the positive electrode current collector (usually aluminum foil) is usually 8-15 μm, the thickness of the negative electrode current collector is 4.5-10 μm, and the volume of the current collector accounts for 2-10% of the total pole piece volume. However, the metal wire added to the positive electrode / negative electrode without current collector of the present invention is usually only 0.02-2% of the total solid content, and the energy density of the overall battery is higher than that of the conventional pole piece manufacturing. battery; due to the addition of the metal wire, the film resistivity of the positive electrode sheet is reduced from 5-100Ω·cm to 0.01-3Ω·cm. During the charge and discharge process of the battery, the potential difference in the thickness direction of the electrode sheet is smaller. Under the same performance, the thickness of the active material layer can be increased, which is beneficial to further improve the energy density of the battery; the present invention directly attaches the positive electrode slurry / negative electrode slurry containing the metal wire to the diaphragm, so that the positive electrode / negative electrode active material and the diaphragm are more closely combined, the internal resistance of the battery cell is reduced, and the cycle life of the battery cell is improved.

[0098] Based on the same inventive concept, the present invention also provides a battery without a current collector, comprising at least one positive electrode sheet without a current collector and at least one negative electrode sheet without a current collector;

[0099] The positive electrode sheets without current collectors and the negative electrode sheets without current collectors are alternately stacked.

[0100] Specifically, refer to Figure 3 As shown, it shows that the positive electrode sheets without current collectors and the negative electrode sheets without current collectors are arranged alternately and stacked. If the positive electrode sheets without current collectors are marked as A and the negative electrode sheets without current collectors are marked as B, then the positive electrode sheets without current collectors and the negative electrode sheets without current collectors are arranged in an ABABABAB manner, with AB alternately arranged in sequence.

[0101] In some embodiments, the battery without a current collector also includes an electrolyte. Specifically, the electrolyte is a conventional lithium battery electrolyte, such as the electrolyte, measured by mass percentage, including the following components: electrolyte salt: 10% to 15%, additives: 0% to 15%, and organic solvent: 75% to 90%; the organic solvent is mainly used as a transport carrier for lithium ions, and commonly used ones are carbonate solvents, such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc.; the electrolyte salt, that is, the lithium salt, is a provider of lithium ions, and lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), a new lithium salt lithium bis(fluorosulfonyl)imide (LiFSI), etc. are usually selected; the additive is a substance with specific functions, such as film-forming additives, high / low temperature additives, overcharge protection additives, flame retardant additives, rate type additives, etc. Common additives include vinylene carbonate (VC), fluoroethylene carbonate (FEC), PS, DTD, etc.

[0102] In some embodiments, the battery without current collector of the present invention comprises positive electrode sheets without current collector and negative electrode sheets without current collector alternately stacked, or positive electrode sheets without current collector and negative electrode sheets without current collector alternately stacked and then wound together to form a bare battery cell; after the bare battery cell is loaded into a casing, it is dried, injected with electrolyte, formed, and divided into volumes to produce a current collector-free battery cell, that is, a battery without current collector is obtained.

[0103] Specifically, in some embodiments, positive electrode sheets without current collectors and negative electrode sheets without current collectors are alternately stacked in sequence in a positive and negative manner, all positive electrode tabs are welded together, all negative electrode tabs are welded together, and are respectively welded to external tabs to form a bare battery cell.

[0104] The following further describes the positive electrode slurry containing metal wire, the negative electrode slurry, the positive electrode sheet without current collector, the positive electrode sheet and the battery of the present application with specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0105] Example 1

[0106] The embodiment of the present application provides a positive electrode slurry containing metal wires, including a positive electrode active material, a conductive agent, a positive electrode binder, a positive electrode solvent and metal wires;

[0107] The positive electrode active material is lithium cobalt oxide; the conductive agent is carbon nanotubes; the positive electrode binder is PVDF; the positive electrode solvent is NMP; the metal wire is aluminum wire, the diameter of the metal wire is 5 μm, and the aspect ratio is 500;

[0108] The mass ratio of the positive electrode active material, the conductive agent, the positive electrode binder, the positive electrode solvent and the metal wire is 98.2:0.6:1.0:60:0.2.

[0109] The method for preparing the positive electrode slurry containing metal wires comprises the following steps:

[0110] The positive electrode active material, the conductive agent and the positive electrode binder are added to the positive electrode solvent and mixed in a planetary mixer, and then the metal wire is added and stirred evenly to obtain a positive electrode slurry containing the metal wire.

[0111] The present application also provides a positive electrode sheet without a current collector, and the preparation method thereof comprises the following steps:

[0112] The positive electrode slurry containing metal wire prepared in Example 1 was coated on the surface of the diaphragm, and the surface density was controlled to be 1.74 g / 100 cm 2 , place a 10μm thick aluminum foil as the positive electrode tab at the edge of the positive electrode slurry, and the aluminum foil and the positive electrode slurry overlap by 2mm (i.e. Figure 1 The middle separator overlaps for 2 m in its length direction (i.e., left-right direction) and is dried in a drying oven to form a positive electrode active material layer. The surface density of the positive electrode slurry after drying is 1.74 g / 100 cm 2 , that is, a positive electrode sheet without a current collector is obtained;

[0113] Among them, the diaphragm is a PE diaphragm containing an aluminum oxide coating (that is, the PE diaphragm is coated with an aluminum oxide coating, purchased from Yunnan Enjie New Materials Co., Ltd., and the positive electrode slurry is coated on the surface of the aluminum oxide coating), the thickness of the PE diaphragm is 5μm, and the thickness of the aluminum oxide coating is 2μm.

[0114] Example 2

[0115] The embodiment of the present application provides a negative electrode slurry containing metal wire, including a negative electrode active material, a conductive agent, a thickener, a negative electrode binder, a negative electrode solvent, and metal wire;

[0116] Among them, the negative electrode active material is artificial graphite; the conductive agent is conductive carbon black; the thickener is CMC; the negative electrode binder is SBR; the negative electrode solvent is water; the metal wire is copper metal wire, the diameter of the metal wire is 3μm, and the aspect ratio is 1000;

[0117] The mass ratio of the negative electrode active material, the conductive agent, the thickener, the negative electrode binder, the negative electrode solvent, and the metal wire is 97.2:0.3:1.1:1.3:75:0.1.

[0118] The method for preparing the negative electrode slurry containing metal wires comprises the following steps:

[0119] The negative electrode active material, conductive agent and thickener are added to the negative electrode solvent and mixed in a planetary mixer, and then the negative electrode binder and metal wire are added and stirred evenly to obtain a negative electrode slurry containing metal wire.

[0120] The present application also provides a negative electrode sheet without a current collector, and a preparation method thereof comprises the following steps:

[0121] The negative electrode slurry containing metal wire prepared in Example 2 was coated on the surface of the separator, and a copper foil with a thickness of 5 μm was placed on the edge of the positive electrode slurry as the negative electrode tab. The copper foil and the negative electrode slurry overlapped by 2 mm (i.e. Figure 2 The middle separator overlaps for 2 m in its longitudinal direction (i.e., left-right direction) and is dried in a drying oven to form a negative electrode active material layer. The surface density of the negative electrode slurry after drying is 0.995 g / 100 cm 2 , that is, a negative electrode sheet without a current collector is obtained;

[0122] Among them, the diaphragm is a PE diaphragm containing an aluminum oxide coating (that is, the PE diaphragm is coated with an aluminum oxide coating, purchased from Yunnan Enjie New Materials Co., Ltd., and the negative electrode slurry is coated on the surface of the aluminum oxide coating), the thickness of the PE diaphragm is 5μm, and the thickness of the aluminum oxide coating is 2μm.

[0123] Example 3

[0124] This embodiment provides a battery without a current collector, and the preparation method thereof is as follows:

[0125] S1. After rolling, the positive electrode sheet without current collector in Example 1 and the negative electrode sheet without current collector in Example 2 are alternately stacked in 17 layers in sequence, all positive electrode tabs are welded together, all negative electrode tabs are welded together, and are respectively welded to external tabs to form a bare battery cell;

[0126] S2, after the bare battery cell is loaded into the aluminum-plastic film, it is sealed on the top and side to form a dry battery cell;

[0127] S3, the dry cell is dried, and the electrolyte is injected after the moisture content is qualified, and then it is formed and divided into volumes to make a finished cell, and a battery without a current collector is obtained;

[0128] The electrolyte includes 15% by mass of electrolyte salt and 85% by mass of organic solvent, the electrolyte salt is LiPF6, the organic solvent includes a mixed solvent of EC and DEC, and the volume ratio of EC to DEC is 1:1.

[0129] Comparative Example 1

[0130] This comparative example provides a positive electrode slurry, including a positive electrode active material, a conductive agent, a binder, and a positive electrode solvent;

[0131] Among them, the positive electrode active material is lithium cobalt oxide; the conductive agent is carbon nanotubes; the binder is PVDF; the positive electrode solvent is NMP;

[0132] The mass ratio of the positive electrode active material, the conductive agent, the binder, and the positive electrode solvent is 98.2:0.8:1.0:60.

[0133] The method for preparing the positive electrode slurry comprises the following steps:

[0134] The positive electrode active material, the conductive agent and the binder are added to the positive electrode solvent, and the mixture is mixed in a planetary mixer and stirred evenly to obtain a positive electrode slurry.

[0135] This comparative example also provides a positive electrode sheet, and the preparation method thereof comprises the following steps:

[0136] The positive electrode slurry prepared in the above comparative example 1 was coated on an aluminum foil with a thickness of 10 μm (as a positive electrode current collector) and dried in a drying oven to form a positive electrode active material layer. After drying, the surface density of the positive electrode slurry was 1.74 g / 100 cm 2 , the positive electrode sheet is obtained, and the part of the aluminum foil not coated with the active material layer is cut out with a laser to obtain the foil ear.

[0137] This comparative example also provides a negative electrode slurry, including a negative electrode active material, a conductive agent, a thickener, a binder, and a negative electrode solvent;

[0138] Among them, the negative electrode active material is artificial graphite; the conductive agent is conductive carbon black; the thickener is CMC; the binder is SBR; the negative electrode solvent is water;

[0139] The mass ratio of the negative electrode active material, the conductive agent, the thickener, the binder, and the negative electrode solvent is 97.2:0.4:1.1:1.3:75.

[0140] The method for preparing the negative electrode slurry comprises the following steps:

[0141] The negative electrode active material, the conductive agent and the thickener are added to the negative electrode solvent and mixed in a planetary mixer, and then the binder is added and stirred evenly to obtain the negative electrode slurry.

[0142] This comparative example also provides a negative electrode sheet, and the preparation method thereof comprises the following steps:

[0143] The negative electrode slurry prepared in the above comparative example 1 was coated on a copper foil with a thickness of 5 μm (as a negative electrode current collector) and dried in a drying oven to form a negative electrode active material layer, i.e., a negative electrode sheet. The surface density of the negative electrode slurry after drying was 0.995 g / 100 cm 2 The copper foil not coated with the active material layer is cut out with a laser to produce the foil tabs.

[0144] This comparative example also provides a battery, and its preparation method is as follows:

[0145] S1. After the positive electrode sheet and the negative electrode sheet in comparative example 1 are rolled, 17 layers of positive electrode sheet, separator, negative electrode sheet and separator are alternately stacked in sequence, all positive electrode tabs are welded together, all negative electrode tabs are welded together, and are respectively welded to the external tabs to make a bare battery cell;

[0146] S2, after the bare battery cell is loaded into the aluminum-plastic film, it is sealed on the top and side to form a dry battery cell;

[0147] S3, the dry cells are dried, and the electrolyte is injected after the moisture content is qualified, and then the cells are formed and divided into different volumes to obtain finished cells and batteries;

[0148] The electrolyte includes 15% by mass of electrolyte salt and 85% by mass of organic solvent, the electrolyte salt is LiPF6, and the organic solvent includes a mixed solvent of EC and DEC, and the volume ratio of EC to DEC is 1:1. Performance test

[0149] The battery without current collector in Example 3 and the battery in Comparative Example 1 were subjected to performance tests, and the results are shown in Table 1 below.

[0150] Table 1 - Performance of the batteries in Example 3 and Comparative Example 1

[0151]

[0152]

[0153] It can be seen from Table 1 that compared with the battery in Comparative Example 1, the resistivity of the positive electrode sheet of the battery without current collector in Example 3 is reduced from 37.3Ω·cm to 2.9Ω·cm; and compared with the battery in Comparative Example 1, the volume energy density and mass energy density of the battery without current collector in Example 3 are greatly improved, while the rate performance, low-temperature discharge performance and cycle performance are comparable.

[0154] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A positive electrode slurry containing metal wires, characterized in that: Including positive electrode slurry and metal wire.

2. The positive electrode slurry containing metal wires according to claim 1, characterized in that: The metal wire comprises at least one of a copper metal wire, an aluminum metal wire, a nickel metal wire, a silver metal wire, and a gold metal wire; And / or, the diameter of the metal wire is 0.1 to 200 μm, preferably, the diameter of the metal wire is 2 to 20 μm; And / or, the aspect ratio of the metal wire is 20-5000, preferably, the aspect ratio of the metal wire is 200-1000.

3. The positive electrode slurry containing metal wires according to any one of claims 1 to 2, characterized in that: The positive electrode slurry comprises a positive electrode active material, a conductive agent, a positive electrode binder, and a positive electrode solvent, and the mass of the metal wire is 0.02 to 2% of the mass of the total solid matter in the positive electrode slurry containing the metal wire; Preferably, the mass of the metal wire is 0.1-0.5% of the mass of the total solid matter in the positive electrode slurry.

4. The positive electrode slurry containing metal wires according to claim 3, characterized in that: The positive electrode active material includes at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, sodium nickel cobalt manganese oxide, composite sodium iron pyrophosphate, sodium ferrous sulfate, and sodium vanadium phosphate; and / or, the conductive agent comprises at least one of conductive carbon black, conductive graphite, carbon nanotubes, graphene and nano-carbon fibers; And / or, the positive electrode binder includes at least one of PVDF, PTFE, CMC, SBR, PAN, and PAA; And / or, the cathode solvent includes at least one of NMP and water; And / or, the mass ratio of the positive electrode active material, the conductive agent, the positive electrode binder, the positive electrode solvent, and the metal wire in the positive electrode slurry containing the metal wire is (90-98.6):(0.01-5):(0.1-5):(40-100):(0.02-2).

5. A negative electrode slurry containing metal wire, characterized in that: Including negative electrode slurry and metal wire.

6. The negative electrode slurry containing metal wires according to claim 5, characterized in that: The metal wire comprises at least one of a copper metal wire, an aluminum metal wire, a nickel metal wire, a silver metal wire, and a gold metal wire; And / or, the diameter of the metal wire is 0.1 to 200 μm, preferably, the diameter of the metal wire is 2 to 20 μm; And / or, the aspect ratio of the metal wire is 20-5000, preferably, the aspect ratio of the metal wire is 200-1000.

7. The negative electrode slurry containing metal wires according to any one of claims 5 to 6, characterized in that: The negative electrode slurry includes a negative electrode active material, a conductive agent, a thickener, a negative electrode binder and a negative electrode solvent, and the mass of the metal wire is 0.02-2% of the mass of the total solid matter in the negative electrode slurry containing the metal wire; Preferably, the mass of the metal wire is 0.1-0.5% of the mass of the total solid matter in the negative electrode slurry.

8. The negative electrode slurry containing metal wires according to claim 7, characterized in that: The negative electrode active material includes at least one of graphite, soft carbon, hard carbon, silicon-based compounds, titanium-based compounds, and phosphorus-based compounds; and / or, the conductive agent comprises at least one of conductive carbon black, conductive graphite, carbon nanotubes, graphene and nano-carbon fibers; And / or, the thickener comprises CMC; And / or, the negative electrode binder includes one of SBR, PVDF, PAN, PI, and PAA; And / or, the negative electrode solvent includes at least one of water and NMP; And / or, the mass ratio of the negative electrode active material, the conductive agent, the thickener, the negative electrode binder, the negative electrode solvent, and the metal wire in the negative electrode slurry containing the metal wire is (90-98.6):(0.01-5):(0.2-3):(0.2-5):(40-130):(0.02-2).

9. A positive electrode sheet without a current collector, characterized in that: include: A diaphragm, wherein a positive electrode active material layer is provided on the surface of the diaphragm, wherein the positive electrode active material layer is obtained by coating the positive electrode slurry containing metal wires according to any one of claims 1 to 4 on the surface of the diaphragm and drying; The positive electrode tab is located on one side of the positive electrode active material layer.

10. A negative electrode sheet without a current collector, characterized in that: include: A diaphragm, wherein a negative electrode active material layer is provided on the surface of the diaphragm, wherein the negative electrode active material layer is obtained by coating the negative electrode slurry containing metal wires according to any one of claims 5 to 8 on the surface of the diaphragm and drying; The negative electrode tab is located on one side of the negative electrode active material layer.

11. The positive electrode sheet without current collector according to claim 9 or the negative electrode sheet without current collector according to claim 10, characterized in that: The diaphragm includes at least one of a PE diaphragm, a PP diaphragm, a PP / PE diaphragm, a PP / PE / PP diaphragm, a PE diaphragm with a heat-resistant coating, a PP diaphragm with a heat-resistant coating, a PI diaphragm, a PA diaphragm, and a cellulose diaphragm; The thickness of the heat-resistant coating is 1 to 3 μm, and the heat-resistant coating includes but is not limited to an aluminum oxide coating and a boehmite coating; The thickness of the diaphragm is 3 to 20 μm; The positive electrode tab comprises at least one of aluminum foil, aluminum sheet, foamed aluminum, and aluminum wire; The negative electrode tab includes at least one of nickel foil, nickel sheet, nickel wire, foamed nickel, copper foil, copper sheet, copper wire, foamed copper, aluminum foil, aluminum sheet, foamed aluminum, and aluminum wire.

12. A battery without a current collector, comprising at least one positive electrode sheet without a current collector as claimed in any one of claims 9 and 11 and at least one negative electrode sheet without a current collector as claimed in any one of claims 10 and 11; The positive electrode sheets without current collectors and the negative electrode sheets without current collectors are alternately stacked.

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