Electrodes, cells and power systems

Abstract

An electrode, a battery cell and an electric system, wherein the electrode comprises a pole piece and an insulating coating, wherein the insulating coating is arranged on the pole piece, and the insulating coating comprises a polymer material, an inorganic filler and a surfactant. The battery cell provided by the present invention can solve the problem that the existing battery cell diaphragm has poor adhesion and is easy to wrinkle or break.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary batteries, and in particular to an electrode, a battery cell and a power system. Background Art

[0002] The battery cell is the core component of the secondary battery function. The battery cell is assembled from a positive electrode, a negative electrode, and a separator located between the positive and negative electrodes. When the positive and negative electrodes are connected to the external circuit to form an electron path and connected to the internal electrolyte to form a lithium ion path, the battery cell generates battery function. In the prior art, the separator is usually relatively independent of the positive and negative electrodes, and its main function is to block the electron path between the positive and negative electrodes while allowing lithium ions to pass through.

[0003] However, in the existing battery cell structure, the diaphragm is easily wrinkled, resulting in insufficient lithium insertion or lithium deposition at the negative electrode corresponding to the wrinkled part of the diaphragm during the charge and discharge process, affecting the battery capacity and even causing safety risks. Summary of the invention

[0004] The purpose of the present invention is to provide an electrode, a battery cell and a power system to solve the problem that the existing battery cell separator has poor adhesion and is easily wrinkled or damaged.

[0005] To achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides an electrode, comprising a pole piece and an insulating coating, wherein the insulating coating is disposed on the pole piece, and the insulating coating comprises a polymer material, an inorganic filler and a surfactant.

[0007] In one embodiment, in the insulating coating, by weight percentage, the polymer material accounts for 50% to 98%, the inorganic filler accounts for 1% to 49% of the inorganic filler, and the surfactant accounts for 0.1% to 1%.

[0008] In one embodiment, the polymer material includes one or more of polyvinylidene fluoride, polyvinyl alcohol, sodium polycarboxymethyl cellulose, and styrene-butadiene rubber.

[0009] In one embodiment, the inorganic filler includes one or more of aluminum oxide, silicon dioxide, and boehmite.

[0010] In one embodiment, the surfactant includes a leveling agent and / or a wetting agent.

[0011] In one embodiment, the insulating coating includes a first sublayer and a second sublayer, the first sublayer is arranged on the pole piece, and the second sublayer is arranged on a side of the first sublayer facing away from the pole piece.

[0012] In one embodiment, in the first sub-layer, the polymer material accounts for 90% to 98%, the inorganic filler accounts for 1% to 9%, and the surfactant accounts for 0.1% to 1%; in the second sub-layer, the polymer material accounts for 20% to 60%, the inorganic filler accounts for 39% to 79%, and the surfactant accounts for 0.1% to 1%.

[0013] In one embodiment, the thickness of the insulating coating is 5 μm to 30 μm.

[0014] In a second aspect, the present invention provides a battery cell, comprising the electrode described in the first aspect, wherein the insulating coating is used to block the electron path between the positive electrode and the negative electrode of the battery cell and allow lithium ions to pass through.

[0015] In a third aspect, the present invention provides an electricity consumption system, characterized in that it includes the battery cell as described in the second aspect.

[0016] In the electrode provided by the present invention, an insulating coating is provided on the pole piece to replace the diaphragm in the prior art; the advantages of the insulating coating are: 1) the insulating coating is provided on the pole piece, so the insulating coating has better adhesion to the pole piece; 2) the insulating coating will not be wrinkled or damaged, which can avoid insufficient lithium insertion or lithium precipitation of the negative electrode; 3) the tightness between the insulating coating and the pole piece is higher than the tightness between the diaphragm and the pole piece, which effectively reduces the impedance of the battery cell; 4) the insulating coating can be provided separately on the pole piece and transported and handled together with the pole piece, which can reduce assembly errors during the assembly process of the battery cell; 5) the preparation process of the insulating coating is less difficult, which can save the production cost of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a schematic diagram of a cross-sectional structure of an electrode according to an embodiment of the present application;

[0019] Figure 2 is a schematic diagram of a cross-sectional structure of an electrode according to another embodiment of the present application;

[0020] Figure 3 is a schematic diagram of a cross-sectional structure of a battery cell according to an embodiment of the present application;

[0021] Figure 4 This is a flow chart of battery cell preparation according to one embodiment of the present application. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in 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.

[0023] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0024] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0025] The present invention provides an electrode, please refer to Figure 1 The electrode includes a pole piece 10 and an insulating coating 30 . The insulating coating 30 is disposed on the pole piece 10 . The insulating coating 30 includes a polymer material, an inorganic filler and a surfactant.

[0026] Specifically, the electrode can be a positive electrode or a negative electrode. When the electrode is a positive electrode, the pole piece 10 is a positive electrode piece, and when the electrode is a negative electrode, the pole piece 10 is a negative electrode piece. Optionally, the positive electrode can be a lithium ion positive electrode or a sodium ion positive electrode, etc., without specific limitation; the negative electrode can be a carbon negative electrode or a silicon negative electrode, etc., without specific limitation. The insulating coating 30 can be provided on the pole piece 10 by roller coating, spraying or gravure printing, etc. The function of the insulating coating 30 is to replace the diaphragm in the existing battery cell technology to avoid the situation where the diaphragm and the positive and negative electrodes are not tightly fitted, and it can also avoid the phenomenon of insufficient lithium insertion or lithium precipitation of the negative electrode caused by wrinkling of the diaphragm, thereby reducing the safety risk of the battery cell.

[0027] It should be explained that the battery cell provided by the present invention does not include a diaphragm, and an insulating coating is used to replace the diaphragm in the prior art. In addition, the insulating coating 30 is formed in situ on the surface of the pole piece 10. It can be understood that the insulating coating 30 is pre-set on the pole piece 10, and then the battery cell is made through the electrode assembly process.

[0028] In the battery cell 100 provided by the present invention, an insulating coating 30 is arranged between the positive electrode and the negative electrode to replace the diaphragm in the prior art; the advantages of the insulating coating 30 are: 1) the insulating coating 30 is arranged on the electrode, so the insulating coating 30 has good adhesion to the electrode; 2) the insulating coating 30 will not be wrinkled or damaged, which can avoid insufficient lithium insertion or lithium precipitation of the negative electrode; 3) the tightness between the insulating coating 30 and the electrode is higher than the tightness between the diaphragm and the electrode, which reduces the impedance of the battery cell; 4) the insulating coating 30 can be arranged separately on the electrode and transported and handled together with the electrode, which can reduce the assembly error during the assembly process of the battery cell 100; 5) the preparation process of the insulating coating is less difficult, which can save the production cost of the battery cell 100.

[0029] In one embodiment, in the insulating coating, by weight percentage, the polymer material accounts for 50% to 98%, the inorganic filler accounts for 1% to 49%, and the surfactant accounts for 0.1% to 1%.

[0030] Specifically, the polymer material has insulating properties, and the polymer material can form a stable coating on the surface of the electrode; and the polymer material can also act as a binder and absorb the electrolyte. The polymer material firmly fixes the inorganic filler in the insulating coating 30, and after being assembled into a battery cell, the polymer material can fully absorb the electrolyte. The inorganic filler can be an inorganic ceramic. The inorganic ceramic plays an insulating role, thereby preventing the electrons in the electrode from passing through the insulating coating 30. The surfactant plays a leveling role in the coating process, making the surface of the insulating coating 30 smoother.

[0031] Optionally, in the insulating coating, the insulating coating 30 may include, by mass percentage, 50% polymer material, 49% inorganic filler and 1% surfactant, or 60% polymer material, 39% inorganic filler and 1% surfactant, or 60% polymer material, 39.5% inorganic filler and 0.5% surfactant, or 80% polymer material, 19% inorganic filler and 1% surfactant, or 80% polymer material, 19.5% inorganic filler and 0.5% surfactant, or 98% polymer material, 1% inorganic filler and 1% surfactant.

[0032] In one embodiment, the polymer material includes one or more of polyvinylidene fluoride, polyvinyl alcohol, sodium polycarboxymethyl cellulose, and styrene-butadiene rubber. The advantages of using the above polymer materials to make the insulating coating 30 are that the above polymer materials are mass-produced in industrial production, so the acquisition cost is low; the above polymer materials are highly environmentally friendly and have excellent performance, will not dissolve in the electrolyte, and are highly stable when used to make the insulating coating 30.

[0033] In one embodiment, the inorganic filler includes one or more of aluminum oxide, silicon dioxide, and boehmite. The advantages of using the above inorganic fillers to make the insulating coating 30 are that the above inorganic fillers are mass-produced in industrial production, so the acquisition cost is low; the above inorganic fillers have stable thermodynamic properties, which can improve the high temperature resistance of the insulating coating 30 and the strength of the insulating coating 30.

[0034] In one embodiment, the surfactant includes a leveling agent and / or a wetting agent.

[0035] It needs to be explained that the main function of the leveling agent is to promote the coating to form a flat, smooth and uniform coating film during the drying process. A wetting agent is a substance that can make solid materials more easily wetted by water. It reduces the surface or interfacial tension of solid materials, allowing water to better spread on the surface of solid materials or penetrate into their surface, thereby achieving a wetting effect.

[0036] In a specific embodiment, the surfactant-type leveling agent and wetting agent are mainly composed of anionic surfactants, cationic surfactants and non-ionic surfactants, which can reduce the surface tension of the coating and improve the fluidity of the coating; and form a uniform wetting film layer on the surface of the object, thereby reducing the surface tension and improving the surface wetting performance.

[0037] Optionally, the surfactant includes a fluorosilicone surfactant and a fluorocarbon surfactant, such as BNK-4036, FS-918, FS-8500, and the like.

[0038] In one implementation, please refer to Figure 2 The insulating coating 30 includes a first sublayer 31 and a second sublayer 32 . The first sublayer 31 is connected to the pole piece 10 , and the second sublayer 32 is connected to a side of the first sublayer 31 facing away from the pole piece 10 .

[0039] In one embodiment, the polymer material in the first sublayer 31 accounts for 90% to 98%, the inorganic filler accounts for 1% to 9%, and the surfactant accounts for 0.1% to 1%; the polymer material in the second sublayer 32 accounts for 20% to 60%, the inorganic filler accounts for 39% to 79%, and the surfactant accounts for 0.1% to 1%.

[0040] Specifically, the insulating coating 30 on the pole piece 10 can be divided into at least two layers, namely a first sublayer 31 and a second sublayer 32. The first sublayer 31 is connected to the pole piece 10, and the second sublayer 32 is connected to the side of the first sublayer 31 facing away from the pole piece 10. The first sublayer 31 contains a large proportion of polymer materials and a small proportion of inorganic fillers; compared with the first sublayer 31, the second sublayer 32 contains a reduced proportion of polymer materials and an increased proportion of inorganic fillers.

[0041] The advantage of setting the insulating coating 30 as two layers is that the first sublayer 31 has a higher content of polymer materials, which can better combine with the pole piece and improve the safety performance of the battery cell; the second sublayer 32 has an increased content of inorganic fillers, which can improve the ion conductivity and further improve the cycle performance of the battery. The polymer materials or inorganic fillers can be used to give full play to their own functions and ensure the stability of the insulating coating 30.

[0042] In one embodiment, the thickness of the insulating coating 30 is 5 μm to 30 μm. Optionally, the thickness of the insulating coating 30 may be 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 17 μm, 20 μm, 23 μm, 25 μm, 28 μm, or 30 μm. Optionally, the thickness of the insulating coating 30 may be 10 μm to 30 μm.

[0043] When the thickness of the insulating coating 30 is within the above range, the provided insulating coating 30 can be ensured to be similar in thickness to the existing separator, and can improve adhesion and prevent wrinkles while achieving the same function as the separator. In addition, the insulating coating 30 can be prevented from being too thin to be effective, or too thick to cause a decrease in the performance of the battery cell.

[0044] It should be explained that in this embodiment, the thickness of the insulating coating 30 should be the total thickness, that is, in the case of having a first sublayer 31 and a second sublayer 32, the sum of the thicknesses of the first sublayer 31 and the second sublayer 32 should satisfy the above range.

[0045] In one embodiment, the thickness of the first sublayer 31 may be 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 17 μm, 20 μm, or 25 μm; the thickness of the second sublayer 32 may be 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 17 μm, 20 μm, or 25 μm.

[0046] The present invention provides a battery cell 100, please refer to Figure 3 The battery cell 100 includes the electrodes provided in the above embodiment, and the insulating coating 30 in the battery cell 100 is used to block the electron path between the positive electrode and the negative electrode of the battery cell 100 and allow lithium ions to pass through.

[0047] In one embodiment, the battery cell 100 includes two pole sheets 10, the two pole sheets 10 are respectively a positive pole sheet and a negative pole sheet, and the insulating coating 30 is disposed between the two pole sheets 10. The insulating coating 30 is suitable for blocking the electron path between the two pole sheets 10 and allowing lithium ions to pass through.

[0048] Specifically, the insulating coating 30 can be disposed on any one of the two electrode sheets 10. In a specific embodiment, the insulating coating 30 can be disposed on the positive electrode sheet, or the insulating coating 30 can be disposed on the negative electrode sheet. It can be understood that the insulating coating 30 is disposed between the two electrode sheets 10, so that the insulating coating 30 is used as a diaphragm.

[0049] In one embodiment, both pole pieces 10 are provided with an insulating coating 30 .

[0050] Specifically, a first insulating coating is provided on the positive electrode sheet, and a second insulating coating is provided on the negative electrode sheet. Therefore, the battery cell can be a combination of a positive electrode sheet and a first insulating coating, and a combination of a negative electrode sheet and a second insulating coating, and then the positive electrode sheet provided with the first insulating coating is directly assembled with the negative electrode sheet provided with the second insulating coating, and the two insulating coatings are combined.

[0051] In one embodiment, the material composition of the first insulating coating is the same as or different from the material composition of the second insulating coating.

[0052] Specifically, both the first insulating coating and the second insulating coating may include polymer materials, inorganic fillers and surfactants. However, the compositions of the various materials of the first insulating coating and the second insulating coating are different; for example, the first insulating coating may include polyvinylidene fluoride, polyvinyl alcohol, and silicon dioxide; and the second insulating coating may include sodium polycarboxymethyl cellulose, polyvinyl alcohol, styrene-butadiene rubber, and ceramics.

[0053] Optionally, the material composition in the first insulating coating may be different from that in the second insulating coating. The type of material in the first insulating coating and the type of material in the second insulating coating may be the same (both include polyvinylidene fluoride, polyvinyl alcohol, and silicon dioxide), but the proportions of each group of materials are different.

[0054] The reason for setting the material composition of the first insulating coating to be different from that of the second insulating coating is that the positive electrode sheet and the negative electrode sheet are made of different materials, so the physical and chemical properties of the positive electrode sheet and the negative electrode sheet are different. Different material compositions are used to make the first insulating coating and the second insulating coating respectively in order to ensure the stability between the insulating coating and the corresponding electrode, and to avoid the coating material from reacting with the electrode or affecting the ion transmission efficiency.

[0055] Furthermore, the material composition of the first insulating coating layer and the material composition of the second insulating coating layer can also be the same, and the purpose of setting the two to be the same is to improve the compatibility of the two after connection, and to avoid the situation where the connection is unstable due to different material compositions. In addition, the same first insulating coating layer and second insulating coating layer are also used to avoid the situation where the coating is set on the positive electrode or the negative electrode alone, resulting in an unstable connection of the other electrode that is not set.

[0056] In one embodiment, the present invention also provides a method for preparing a battery cell, please refer to Figure 4 , the specific steps are as follows:

[0057] Step S10, coating a first coating slurry on the surface of the positive electrode sheet, and curing the first coating slurry to obtain a first insulating coating.

[0058] Step S20, coating a second coating slurry on the surface of the negative electrode sheet, and curing the second coating slurry to obtain a second insulating coating.

[0059] Step S30, assembling the positive electrode sheet and the negative electrode sheet so that the first insulating coating layer and the second insulating coating layer are connected.

[0060] Optionally, in step S10, the method of coating the first coating slurry on the surface of the positive electrode sheet includes: roller coating, spraying, gravure printing, etc.

[0061] Optionally, in step S10, the first coating slurry comprises a solvent, a polymer material, an inorganic filler and a surfactant.

[0062] Optionally, the percentage of each solute component in the first coating slurry is: 50% to 98% polymer material, 1% to 49% inorganic filler, 0.1% to 1% surfactant. The rest can be solvent, and the mass proportion of the solvent in the first coating slurry can be 40% to 80%.

[0063] Optionally, the solvent in the first coating slurry includes NMP (N-methylpyrrolidone) and / or DMSO (dimethyl sulfoxide).

[0064] Optionally, the polymer material in the first coating slurry includes polyvinylidene fluoride and / or polyvinyl alcohol.

[0065] Optionally, the inorganic filler in the first coating slurry includes one or more of aluminum oxide, silicon dioxide, and boehmite.

[0066] Optionally, the surfactant in the first coating slurry includes a leveling agent and / or a wetting agent.

[0067] Optionally, in step S20, the method of coating the second coating slurry on the surface of the negative electrode sheet includes: roller coating, spraying, gravure printing, etc.

[0068] Optionally, in step S20, the second coating slurry comprises a solvent, a polymer material, an inorganic filler and a surfactant.

[0069] Optionally, the percentage of each solute component in the second coating slurry is: 50% to 98% polymer material, 1% to 49% inorganic filler, 0.1% to 1% surfactant. The rest can be solvent, and the mass proportion of the solvent in the second coating slurry can be 50% to 80%.

[0070] Optionally, the solvent in the second coating slurry includes NMP (N-methylpyrrolidone) and / or water.

[0071] Optionally, the polymer material in the second coating slurry includes one or more of sodium polycarboxymethyl cellulose, polyvinyl alcohol, and styrene-butadiene rubber.

[0072] Optionally, the inorganic filler in the second coating slurry includes one or more of aluminum oxide, silicon dioxide, and boehmite.

[0073] Optionally, the surfactant in the second coating slurry includes a leveling agent and / or a wetting agent.

[0074] In one embodiment, the present invention further provides a battery, comprising a housing and the battery cell in the above embodiment, wherein the battery cell is accommodated in the housing.

[0075] In one embodiment, the battery of the present invention further comprises an electrolyte.

[0076] In one embodiment, the present invention further provides an electric power system, comprising the battery in the above embodiment. The electric power system can be an energy storage box or a new energy vehicle.

[0077] The technical solution of the present invention is described in detail below through specific embodiments.

[0078] Example 1

[0079] This embodiment provides a battery cell, which includes a positive electrode and a negative electrode, wherein a first insulating coating is provided on the positive electrode, and a second insulating coating is provided on the negative electrode. The first insulating coating includes PVDF (polyvinylidene fluoride), polyvinyl alcohol, fluorocarbon surfactant FSN100 and silicon dioxide powder; and the second insulating coating includes sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, fluorocarbon surfactant FSN100 and aluminum oxide ceramic.

[0080] The manufacturing method of the battery cell provided in this embodiment is as follows:

[0081] 1) A positive electrode insulating slurry is prepared according to a mass ratio, wherein 50% of NMP, 30% of PVDF, 0.4% of a fluorocarbon surfactant FSN100, 2% of polyvinyl alcohol, and 17.6% of silicon dioxide powder are mixed to form a positive electrode insulating slurry, and the positive electrode insulating slurry is coated on the pressed positive electrode by roller coating. After drying and removing the solvent, a positive electrode is obtained, and the thickness of the first insulating coating layer is 10 μm.

[0082] 2) A negative electrode insulating slurry is prepared according to the mass ratio, and 60% of water, 9% of sodium carboxymethyl cellulose, 9% of styrene-butadiene rubber, 0.4% of fluorocarbon surfactant FSN100, 2% of polyvinyl alcohol, and 19.6% of alumina ceramic are mixed into the negative electrode insulating slurry, and the negative electrode insulating slurry is coated on the pressed negative electrode by roller coating. After drying and removing the solvent, the negative electrode is obtained, and the thickness of the second insulating coating layer is 5 μm.

[0083] 3) Assemble the positive electrode and the negative electrode into a battery cell by stacking them, and inject electrolyte into the cell.

[0084] Example 2

[0085] This embodiment provides a battery cell, which includes a positive electrode and a negative electrode, wherein a first insulating coating is provided on the positive electrode, and a second insulating coating is provided on the negative electrode. The first insulating coating includes PVDF (polyvinylidene fluoride), polyvinyl alcohol, a silane surfactant, and silicon dioxide powder; and the second insulating coating includes sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, a surfactant BNK-4046, and aluminum oxide ceramics.

[0086] The difference between the method for manufacturing the battery cell provided in this embodiment and that in embodiment 1 is that:

[0087] 1) The positive electrode insulating slurry includes: 50% NMP, 20% PVDF, 0.5% silane surfactant, 5% polyvinyl alcohol, and 24.5% silicon dioxide powder.

[0088] 2) The negative electrode insulating slurry includes: 70% water, 10.7% sodium carboxymethyl cellulose, 9% styrene-butadiene rubber, 0.3% surfactant BNK-4046, 1% polyvinyl alcohol, and 9% alumina ceramic.

[0089] Example 3

[0090] This embodiment provides a battery cell, the battery cell includes a positive electrode and a negative electrode, and a first insulating coating is provided on the positive electrode. The first insulating coating includes PVDF (polyvinylidene fluoride), polyvinyl alcohol, fluorocarbon surfactant FSN100 and silicon dioxide powder.

[0091] The difference between the manufacturing method of the battery cell provided in this embodiment and that in Embodiment 1 is that: the second insulating coating is not provided on the negative electrode, and the thickness of the first insulating coating is 30 μm.

[0092] Example 4

[0093] This embodiment provides a battery cell, which includes a positive electrode and a negative electrode, and a second insulating coating is provided on the negative electrode. The second insulating coating includes sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, fluorocarbon surfactant FSN100 and aluminum oxide ceramics.

[0094] The difference between the manufacturing method of the battery cell provided in this embodiment and that in Embodiment 1 is that: the first insulating coating is not provided on the positive electrode, and the thickness of the second insulating coating is 25 μm.

[0095] Example 5

[0096] This embodiment provides a battery cell, which includes a positive electrode and a negative electrode, wherein a first insulating coating is provided on the positive electrode, and a second insulating coating is provided on the negative electrode. The first insulating coating includes PVDF (polyvinylidene fluoride), polyvinyl alcohol, fluorocarbon surfactant FSN100 and silicon dioxide powder; and the second insulating coating includes sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, fluorocarbon surfactant FSN100 and aluminum oxide ceramic.

[0097] The difference between the manufacturing method of the battery cell provided in this embodiment and that in Embodiment 1 is that the thickness of the first insulating coating is 8 μm.

[0098] Example 6

[0099] This embodiment provides a battery cell, which includes a positive electrode and a negative electrode, wherein a first insulating coating is provided on the positive electrode, and a second insulating coating is provided on the negative electrode. The first insulating coating includes PVDF (polyvinylidene fluoride), polyvinyl alcohol, fluorocarbon surfactant FSN100 and silicon dioxide powder; and the second insulating coating includes sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, fluorocarbon surfactant FSN100 and aluminum oxide ceramic.

[0100] The difference between the manufacturing method of the battery cell provided in this embodiment and that in Embodiment 1 is that the thickness of the second insulating coating is 10 μm.

[0101] Example 7

[0102] This embodiment provides a battery cell, which includes a positive electrode and a negative electrode, wherein a first insulating coating is provided on the positive electrode, and a second insulating coating is provided on the negative electrode. The first insulating coating includes PVDF (polyvinylidene fluoride), polyvinyl alcohol, fluorocarbon surfactant FSN100 and silicon dioxide powder; and the second insulating coating includes sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, fluorocarbon surfactant FSN100 and aluminum oxide ceramic.

[0103] The difference between the manufacturing method of the battery cell provided in this embodiment and that in Embodiment 1 is that the ratio of the positive electrode insulating slurry is 50% NMP, 16% PVDF, 1% fluorocarbon surfactant FSN100, 4% polyvinyl alcohol, and 29% silicon dioxide powder.

[0104] Example 8

[0105] This embodiment provides a battery cell, which includes a positive electrode and a negative electrode, wherein a first insulating coating is provided on the positive electrode, and a second insulating coating is provided on the negative electrode. The first insulating coating includes PVDF (polyvinylidene fluoride), polyvinyl alcohol, fluorocarbon surfactant FSN100 and silicon dioxide powder; and the second insulating coating includes sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, fluorocarbon surfactant FSN100 and ceramics.

[0106] The difference between the manufacturing method of the battery cell provided in this embodiment and that in Embodiment 1 is that the ratio of the negative electrode insulating slurry is 60% water, 8% sodium carboxymethyl cellulose, 8% styrene-butadiene rubber, 0.8% fluorocarbon surfactant FSN100, 2% polyvinyl alcohol, and 21.2% alumina ceramic.

[0107] Example 9

[0108] This embodiment provides a battery cell, which includes a positive electrode and a negative electrode, and a first insulating coating is provided on the positive electrode. The first insulating coating includes PVDF (polyvinylidene fluoride), polyvinyl alcohol, fluorocarbon surfactant FSN100 and silicon dioxide powder; and the negative electrode is not provided with a second insulating coating.

[0109] The manufacturing method of the battery cell provided in this embodiment is different from that of Example 1 in that the first insulating coating includes a first sublayer and a second sublayer, wherein the slurry ratio of the first sublayer is 50% NMP, 36% PVDF, 0.5% fluorocarbon surfactant FSN100, 9% polyvinyl alcohol, and 4.5% silica powder; the slurry ratio of the second sublayer is 50% NMP, 24% PVDF, 0.5% fluorocarbon surfactant FSN100, 6% polyvinyl alcohol, and 19.5% silica powder.

[0110] The thickness of the first sub-layer is 7.5 μm; the thickness of the second sub-layer is 7.5 μm.

[0111] Comparative Example 1

[0112] This comparative example provides a battery cell, in which both the positive electrode and the negative electrode are not coated with an insulating coating, the positive electrode and the negative electrode are separated by a 15 μm separator (PP polypropylene), and the battery cell is formed by stacking and assembling.

[0113] The battery cells obtained in Examples 1-9 and Comparative Example 1 were placed in a housing, injected with liquid and packaged to form a battery cell for the following performance test. The test results are shown in Table 1.

[0114] Short circuit rate test: 1000 cells each prepared in Examples 1-9 and Comparative Example 1 were compressed under a pressure of 0.3 MPa, and then the cells were subjected to a high voltage shock of 100 V or above to test the voltage resistance of the cells. If the voltage dropped by ≤10%, it was considered that there was no short circuit. If the voltage dropped by >10%, it was considered that there was a short circuit. The short circuit rate was then calculated using statistical data.

[0115] Capacity retention rate test: The single cells prepared in Examples 1-9 and Comparative Example 1 were discharged to 2.0 V at 1 / 3C constant current, left for 30 min, charged to 3.8 V at 1 / 3C constant current, left for 30 min, discharged to 2.0 V at 1 / 3C constant current, recorded the initial capacity, repeated the above steps 500 times, recorded the capacity after 500 cycles, and calculated the capacity retention rate.

[0116] DCIR test: At room temperature, the above battery was discharged at 1 / 3C constant current to 2.0V, left for 30min, charged at 1 / 3C constant current to 50% SOC, discharged at 1.5C constant current for 30S at 25℃, the voltage before and after discharge was recorded, and the discharge DCIR (mΩ) was calculated as (pre-discharge voltage - post-discharge voltage) / discharge current * 1000.

[0117] Table 1

[0118] Short circuit rate (%) DCIR(mΩ) 500 cycles capacity retention rate (%) Example 1 0.6 0.55 93.5 Example 2 0.8 0.56 94 Example 3 0.6 0.52 95 Example 4 0.9 0.54 94.5 Example 5 0.9 0.52 95 Example 6 0.5 0.51 96 Example 7 1.2 0.57 95 Example 8 1.1 0.56 95 Example 9 0.5 0.52 94 Comparative Example 1 2 0.61 92

[0119] It can be seen from the test data of Examples 1-9 and Comparative Example 1 in Table 1 that the short circuit rate and DC internal resistance of the battery provided by the present invention are lower than those of the existing common battery, and the capacity retention rate is also greater than that of the existing common battery. This shows that the performance of the battery obtained by replacing the diaphragm with the insulating coating is better than that of the existing common battery.

[0120] It can be seen from the test data of Example 1 and Example 2 in Table 1 that the insulating coating provided by the present invention can use different slurry formulations, and all of them can achieve the effect of improving the performance of the battery cell.

[0121] It can be seen from the test data of Example 1, Example 3 and Example 4 in Table 1 that the battery cell can also be manufactured by providing an insulating coating on the positive electrode or the negative electrode. Moreover, the method of providing an insulating coating only on the positive electrode or the negative electrode has simple process steps, and the battery cell performance is still better than the existing ordinary battery cells.

[0122] It can be seen from the test data of Example 1, Example 5 and Example 6 in Table 1 that the performance of the battery cell can be adjusted by the thickness of the insulating coating on the positive electrode or the negative electrode.

[0123] It can be seen from the test data of Example 1, Example 7 and Example 8 in Table 1 that when the proportion of each component in the insulating coating is not within the range provided by the present invention, the performance of the battery cell is slightly reduced, but is still better than that of ordinary battery cells.

[0124] It can be seen from the test data of Example 1 and Example 9 in Table 1 that the insulating coating can be divided into two layers (including a first sublayer and a second sublayer), and the electrical performance of the battery cell can be further improved by providing an inorganic filler in the second sublayer to improve the ion conductivity.

[0125] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientation or positional relationship described in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0126] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. An electrode, characterized in that: The electrode comprises a pole piece and an insulating coating, wherein the insulating coating is arranged on the pole piece and comprises a polymer material, an inorganic filler and a surfactant.

2. The electrode according to claim 1, characterized in that In the insulating coating, by weight percentage, the polymer material accounts for 50% to 98%, the inorganic filler accounts for 1% to 49%, and the surfactant accounts for 0.1% to 1%.

3. The electrode according to claim 1 or 2, characterized in that The polymer material includes one or more of polyvinylidene fluoride, polyvinyl alcohol, sodium polycarboxymethyl cellulose, and styrene-butadiene rubber.

4. The electrode according to claim 1 or 2, characterized in that: The inorganic filler includes one or more of aluminum oxide, silicon dioxide and boehmite.

5. The electrode according to claim 1 or 2, characterized in that: The surfactant includes a leveling agent and / or a wetting agent.

6. The electrode according to claim 1, characterized in that The insulating coating comprises a first sublayer and a second sublayer, wherein the first sublayer is arranged on the pole piece, and the second sublayer is arranged on a side of the first sublayer facing away from the pole piece.

7. The electrode according to claim 6, characterized in that In the first sub-layer, the polymer material accounts for 90% to 98%, the inorganic filler accounts for 1% to 9%, and the surfactant accounts for 0.1% to 1%; in the second sub-layer, the polymer material accounts for 20% to 60%, the inorganic filler accounts for 39% to 79%, and the surfactant accounts for 0.1% to 1%.

8. The electrode according to claim 1, characterized in that The thickness of the insulating coating is 5 μm to 30 μm.

9. A battery cell, characterized in that: Comprising the electrode as described in any one of claims 1 to 8, the insulating coating is used to block the electron path between the positive electrode and the negative electrode of the battery cell and allow lithium ions to pass through.

10. An electricity system, characterized in that: Comprising the battery cell as claimed in claim 9.

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