Electrode plate, electrode assembly and secondary battery

Abstract

The present application provides an electrode plate, an electrode assembly, and a secondary battery. The electrode plate includes a current collector, an active material layer disposed on one surface of the current collector, and an electrical connection member electrically connected to the current collector, the active material layer being disposed on a main body of the current collector, the electrical connection member and the current collector being welded and connected at an edge of the current collector, the welded connection area being called a relay welding area, the current collector includes a support layer and a conductive layer disposed on one surface of the support layer, and the electrode plate further includes a first insulating layer disposed on another surface of the current collector and covering at least the entire relay welding area when viewed in the thickness direction of the electrode plate. According to the present application, the safety performance of the secondary battery can be improved and the internal resistance of the secondary battery can be reduced.

Description

[Technical Field]

[0001] The present application relates to the field of batteries, and in particular to electrodes, electrode assemblies and secondary batteries. [Background technology]

[0002] In recent years, secondary batteries have advantages such as high energy density, high output power, long cycle life, and low environmental pollution, and therefore have been widely applied in energy storage power systems such as hydroelectric, thermal, wind, and solar power plants, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, consumer electronic products, military equipment, aerospace, etc. As secondary batteries have made great strides in development, higher requirements are being placed on their energy density, cycle performance, safety performance, etc.

[0003] The prior art discloses a current collector that includes a dense support layer and a dense conductive layer disposed on at least one surface of the support layer. However, because the conventional tab-forming structure of the current collector does not allow for a conductive structure along the thickness direction of the battery, it is necessary to relay-weld a metal tab to the edge of the current collector using ultrasonic welding. As such, the current collector has problems such as a short circuit due to metal burn-through when welding the metal tab to the current collector, which reduces the safety of the secondary battery using the current collector, and metal slag falling to other areas during welding, which increases the internal resistance of the secondary battery. Summary of the Invention

[0004] The present application has been made in view of the above technical problems, and its object is to provide an electrode plate, an electrode assembly, a secondary battery, a battery module, a battery pack, and a power consumption device that can reliably prevent short circuits caused by metal burn-through during welding, thereby improving the safety of secondary batteries that use the electrode plate and reducing the internal resistance of the secondary batteries.

[0005] To achieve the above object, the present application provides an electrode plate, an electrode assembly, a secondary battery, a battery module, a battery pack, and a power consumption device, each including a first insulating layer that is disposed on another surface of a current collector and that covers at least the entire relay welding area when viewed in the thickness direction.

[0006] A first aspect of the present application provides an electrode plate, the electrode plate including a current collector, an active material layer disposed on one surface of the current collector, and an electrical connection member electrically connected to the current collector, the active material layer being disposed on a main body portion of the current collector, the electrical connection member and the current collector being welded together at an edge of the current collector, the welded connection area being referred to as an intermediate welding area, the current collector including a support layer and a conductive layer disposed on one surface of the support layer, the electrode plate further including a first insulating layer disposed on another surface of the current collector and covering at least the entire intermediate welding area when viewed in the thickness direction of the electrode plate.

[0007] Therefore, in the present application, a first insulating layer is provided on another surface of the current collector, covering at least the entire intermediate welding area when viewed in the thickness direction of the electrode plate. By doing so, when the electrical connection member and the current collector are welded to one surface of the current collector, even if slag generated during welding due to burn-through of the conductive layer and support layer of the current collector and particles that fall in subsequent processes fall through the burn-through conductive layer and support layer onto the film area where the active material layer is to be installed, the first insulating layer located on the other surface of the current collector acts as a protection against the slag and particles from falling onto the film area, thereby reliably preventing short circuits due to metal burn-through during welding, thereby improving the safety of secondary batteries using this electrode plate and reducing the internal resistance of the secondary battery.

[0008] In any embodiment, the support layer is made of an insulating material having a fibrous pore structure, which can improve the ion permeability of the support layer and thereby effectively improve the electrochemical performance.

[0009] In any embodiment, the support layer is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof, thereby ensuring that the support layer has high ion permeability.

[0010] In any embodiment, an edge of the first insulating layer overlaps an edge of the active material layer when viewed in the thickness direction of the electrode plate. In order to prevent adverse effects on the active material layer due to the welding of the electrical connection member, the intermediate welding region where the electrical connection member is welded is preferably located outside the edge of the active material layer when viewed in the thickness direction of the electrode plate. Therefore, by overlapping the edge of the first insulating layer and the edge of the active material layer when viewed in the thickness direction of the electrode plate, it is possible to reliably ensure that the first insulating layer covers the entire intermediate welding region when viewed in the thickness direction of the electrode plate.

[0011] In any embodiment, the first insulating layer is made of a resin material and is the same material as the support layer, thereby improving the ion permeability of the first insulating layer and thereby effectively improving the electrochemical performance.

[0012] In any embodiment, the first insulating layer is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof, or the first insulating layer is an adhesive or a resin material. By forming the first insulating layer from a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof, a first insulating layer with high ion permeability can be reliably formed. Furthermore, a first insulating layer formed from an adhesive or a resin material can be easily formed by coating or the like.

[0013] In an optional embodiment, the electrode plate further includes a second insulating layer disposed on one surface of the electrical connection member and covering at least the entire intermediate welding area when viewed in the thickness direction of the electrode plate, thereby filling the crimping holes caused by the welding traces with the second insulating layer and preventing slag generated during welding and particles dropped during subsequent processes from falling into the crimping holes, thereby preventing the occurrence of hip-po defects and reducing the DC internal resistance of the secondary battery.

[0014] In any embodiment, the second insulating layer is an adhesive or a resin material, which allows the caulking holes formed by welding marks to be reliably filled with the adhesive or resin material.

[0015] In some embodiments, a primer layer is disposed between the active material layer and the current collector, and optionally, the width of the primer layer is 1 mm to 3 mm smaller than the width of the active material layer. By disposing the primer layer between the active material layer and the current collector, the adhesion between the current collector and the active material can be improved, ensuring that the active material layer is more firmly attached to the surface of the current collector. The primer layer also improves the overcurrent capacity and electrochemical performance of the electrode plate. Furthermore, the width of the primer layer is 1 mm to 3 mm smaller than the width of the active material layer, thereby preventing poor welding and dummy welding due to contact between the electrical connection member and the primer layer.

[0016] A second aspect of the present application provides an electrode assembly, comprising a first electrode plate and a second electrode plate, one of which is the electrode plate according to the first aspect of the present application, and positioned such that a support layer of one of the first electrode plate and the second electrode plate is in intimate contact with another of the first electrode plate and the second electrode plate.

[0017] A third aspect of the present application further provides an electrode assembly, wherein the electrode assembly includes a first electrode plate and a second electrode plate, each of which is the electrode plate described in the first aspect of the present application, wherein a support layer of the first electrode plate is disposed in intimate contact with an active material layer of the second electrode plate, and a support layer of the second electrode plate is disposed in intimate contact with an active material layer of the first electrode plate.

[0018] A fourth aspect of the present application provides a secondary battery, wherein the secondary battery includes the electrode plate according to the first aspect of the present application, or the electrode assembly according to the second or third aspect of the present application.

[0019] A fifth aspect of the present application provides a battery module, wherein the battery module includes the secondary battery according to the fourth aspect of the present application.

[0020] A sixth aspect of the present application provides a battery pack, wherein the battery pack includes the battery module according to the fifth aspect of the present application.

[0021] A seventh aspect of the present application provides a power consumption device, wherein the power consumption device includes at least one selected from the secondary battery described in the fourth aspect of the present application, the battery module described in the fifth aspect of the present application, and the battery pack described in the sixth aspect of the present application.

[0022] According to the present application, it is possible to reliably prevent short circuits caused by metal burn-through during welding. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 2 is a cross-sectional view of a plate according to an embodiment of the present application. [Figure 2] FIG. 2 is a plan view of a plate according to an embodiment of the present application. [Figure 3] FIG. 2 is a bottom view of the tab portion of the plate of one embodiment of the present application. [Figure 4] FIG. 2 is a plan view of a tab portion of a plate according to one embodiment of the present application. [Figure 5]FIG. 1 is a cross-sectional view of an electrode assembly according to an embodiment of the present application. [Figure 6] FIG. 6 is a plan view of the electrode assembly shown in FIG. 5 after winding. [Figure 7] FIG. 1 is a cross-sectional view of an electrode assembly according to an embodiment of the present application. [Figure 8] FIG. 6 is a plan view of the electrode assembly shown in FIG. 5 after winding. [Figure 9] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 10] FIG. 10 is an exploded view of the secondary battery shown in FIG. 9 according to an embodiment of the present application. [Figure 11] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 12] 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 13] FIG. 12 is an exploded view of the battery pack of one embodiment of the present application shown in FIG. 11. [Figure 14] 1 is a schematic diagram of an embodiment of a power consuming device in which the secondary battery of the present application is used as a power source; DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments specifically disclosing the electrode plate, electrode assembly, secondary battery, battery module, battery pack, and power consumption device of the present application will be described in detail with appropriate reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of actually identical structures may be omitted. This is to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0025] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit that define the boundaries of the particular range. Such defined ranges may or may not include the end values and may be arbitrarily combined, i.e., any lower limit and any upper limit may be combined to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are recited for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values of 1 and 2 and maximum range values of 3, 4, and 5 are recited, all of the following ranges are contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise specified, a numerical range "a to b" is a shorthand expression representing all combinations of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed herein, with "0-5" merely being a shorthand notation for combinations of these numbers. Also, stating that a parameter is an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] Unless otherwise stated, all embodiments and optional embodiments in the present application may be combined with each other to form a new technical solution.

[0027] Unless otherwise stated, all technical features and optional technical features in the present application may be combined with each other to form a new technical solution.

[0028] Unless otherwise specified, all steps in the present application may be performed sequentially or randomly, preferably sequentially. For example, a description of a method including steps (a) and (b) means that the method may include sequential steps (a) and (b), or sequential steps (b) and (a). For example, a description of a method mentioned above further including step (c) means that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0029] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open-ended or closed-ended. For example, the terms "comprise" and "comprises" may further include or include other components not listed, or may include or include only the listed components.

[0030] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any one of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0031] The inventors discovered that because the conductive layer and support layer of a current collector have a dense structure but are thin (compared to typical metal foil sheet current collectors, such as aluminum foil or copper foil), when welding electrical connection components to the edges of the current collector, burn-through is likely to occur in the conductive layer and support layer in the intermediate welding area. If slag generated during welding and particles that fall during subsequent processes fall through the burn-through conductive layer and support layer onto the film area, the battery may self-discharge and ultimately develop an internal short circuit. To solve this problem, the inventors installed a first insulating layer on another surface of the current collector, covering at least the entire intermediate welding area when viewed through the thickness of the plate. This first insulating layer acts as a protection against slag and particles from falling onto the film area, reliably preventing short circuits caused by metal burn-through during welding. The inventors discovered that secondary batteries using this plate have improved safety by preventing internal short circuits, while also reducing the DC internal resistance of the secondary battery by preventing slag from falling into other areas.

[0032] The electrode plate, electrode assembly, secondary battery, battery module, battery pack, and power consuming device of the present application will be described below with appropriate reference to the drawings.

[0033] [Pole plate] In one embodiment of the present application, there is provided an electrode plate. As shown in Figure 1, the electrode plate 6 includes a current collector 61, an active material layer 62 disposed on one surface of the current collector 61, and an electrical connection member 63 electrically connected to the current collector 61. Here, the active material layer 62 is disposed on one surface of the current collector 61 via an undercoat layer 66 (described below), but the active material layer 62 may also be disposed directly on one surface of the current collector 61.

[0034] As shown in Figures 1 and 2, the active material layer 62 is installed on the main body of the current collector 61, and the electrical connection member 63 and the current collector 61 are welded together at the edge of the current collector 61, and this welded connection area is called the relay welding area A.

[0035] The current collector 61 includes a support layer 611 and a conductive layer 612 disposed on one surface of the support layer 611. Compared to conventional metal current collectors, the conductive layer 612 in the current collector of the present application functions as a current collector, conducting current, and providing electrons for the active material layer. The material of the conductive layer is at least one selected from a metal conductive material and a carbon-based conductive material. The metal conductive material is preferably at least one of aluminum, copper, nickel, titanium, silver, and alloys thereof. The carbon-based conductive material is preferably at least one of graphite, acetylene black, graphene, and carbon nanotubes. The material of the conductive layer is preferably a metal conductive material, i.e., the conductive layer is preferably a metal conductive layer. Here, when the current collector is a positive electrode current collector, aluminum is typically used as the material of the conductive layer, and when the current collector is a negative electrode current collector, copper is typically used as the material of the conductive layer. In the current collector of the present application, the support layer serves to support and protect the conductive layer. Since the support layer is generally made of an organic polymer material or a polymer composite material, the density of the support layer is usually lower than the density of the conductive layer, thereby significantly improving the weight energy density of the battery compared to conventional metal current collectors.

[0036] The electrode plate 6 further includes a first insulating layer 64, which is disposed on another surface of the current collector 61 and covers at least the entire relay welding area A when viewed from the thickness direction Y of the electrode plate 6, as shown in FIGS.

[0037] Therefore, in the present application, a first insulating layer is provided on another surface of the current collector, covering at least the entire intermediate welding area when viewed in the thickness direction of the electrode plate. By doing so, when the electrical connection member and the current collector are welded to one surface of the current collector, even if slag generated during welding due to burn-through of the conductive layer and support layer of the current collector and particles that fall in subsequent processes fall through the burn-through conductive layer and support layer onto the film area where the active material layer is to be installed, the first insulating layer located on the other surface of the current collector acts as a protection against the slag and particles from falling onto the film area, thereby reliably preventing short circuits due to metal burn-through during welding, thereby improving the safety of secondary batteries using this electrode plate and reducing the internal resistance of the secondary battery.

[0038] In some embodiments, the support layer 611 is made of an insulating material with a fibrous pore structure, which can improve the ion permeability of the support layer and thereby effectively improve the electrochemical performance.

[0039] In some embodiments, the support layer 611 is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof. By configuring the support layer with a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof, it is possible to reliably configure a support layer with high ion permeability.

[0040] 1 , when viewed in the thickness direction Y of the electrode plate 6, the edge E1 of the first insulating layer 64 overlaps the edge E2 of the active material layer 62. To prevent adverse effects on the active material layer due to the welding of the electrical connection member, the intermediate welding area where the electrical connection member is welded is preferably located outside the edge of the active material layer when viewed in the thickness direction of the electrode plate. Therefore, by making the edge of the first insulating layer overlap the edge of the active material layer when viewed in the thickness direction of the electrode plate, it is possible to reliably ensure that the first insulating layer covers the entire intermediate welding area when viewed in the thickness direction of the electrode plate.

[0041] In some embodiments, the first insulating layer 64 is made of a resin material and is the same material as the support layer 611. This can improve the ion permeability of the first insulating layer, thereby effectively improving the electrochemical performance.

[0042] In some embodiments, the first insulating layer 64 is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof. By using a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof, the first insulating layer can be reliably configured to have high ion permeability. In some embodiments, the first insulating layer 64 is an adhesive or resin material. This allows the insulating layer to be easily formed by coating or the like. The adhesive is not particularly limited and may include one or more of styrene butadiene rubber (SBR), water-based acrylic resin, carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0043] In some embodiments, the electrode plate 6 further includes a second insulating layer 65. As shown in Figures 1 and 4, the second insulating layer 65 is disposed on one surface of the electrical connection member 63 and covers at least the entire intermediate welding area A when viewed in the thickness direction Y of the electrode plate 6. This allows the second insulating layer to fill the crimping holes caused by the welding marks, preventing slag generated during welding and particles that fall during subsequent processes from falling into the crimping holes, thereby preventing the occurrence of hip defects.

[0044] In some embodiments, the second insulating layer 65 is an adhesive or a resin material. This allows the caulking holes caused by the welding marks to be reliably filled with the adhesive or resin material. The adhesive is not particularly limited and may include one or more of styrene butadiene rubber (SBR), water-based acrylic resin, carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0045] In some embodiments, an undercoat layer 66 is disposed between the active material layer 62 and the current collector 61. Optionally, the width of the undercoat layer 66 in the width direction X is 1 mm to 3 mm smaller than the width of the active material layer 62 in the width direction X. By disposing the undercoat layer between the active material layer and the current collector, the adhesion between the current collector and the active material can be improved, ensuring that the active material layer is more firmly attached to the surface of the current collector. The undercoat layer also improves the overcurrent resistance and electrochemical performance of the electrode plate. Furthermore, the width of the undercoat layer is 1 mm to 3 mm smaller than the width of the active material layer, thereby preventing poor welding and dummy welding due to contact between the electrical connection member and the undercoat layer.

[0046] Obviously, the electrode plate in this application may be a positive electrode plate or a negative electrode plate. If the electrode plate is a positive electrode plate, the current collector and active material layer therein are accordingly a positive electrode current collector and a positive electrode active material layer, respectively. If the electrode plate is a negative electrode plate, the current collector and active material layer therein are accordingly a negative electrode current collector and a negative electrode active material layer, respectively.

[0047] When the electrode plate 6 of the present application is a positive electrode plate, the positive electrode plate includes a positive electrode current collector and a positive electrode active material layer disposed on one surface of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material.

[0048] For example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode active material layer is disposed on one of the two facing surfaces of the positive electrode current collector.

[0049] In some embodiments, the positive electrode current collector may be a composite current collector. The composite current collector may include a support layer made of an insulating material having a fibrous pore structure and a conductive layer formed on one surface of the support layer. The composite current collector may be formed by forming a metal material (e.g., aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a support layer (e.g., polyethylene film, polypropylene film, polyvinylidene chloride film, or a multilayer composite film thereof).

[0050] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries well known in the art. For example, the positive electrode active material may include at least one of a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a modified compound of each. However, the present application is not limited to these materials, and other conventional materials usable as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (may be abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (may be abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (may be abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (may be abbreviated as NCM622), LiNi 0.8 Co0.1 Mn 0.1 O2 (which may be abbreviated as NCM811), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof, etc. Examples of the lithium-containing phosphate having an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0051] In some embodiments, the positive electrode active material layer optionally further includes an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0052] In some embodiments, the positive electrode active material layer optionally further includes a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0053] In some embodiments, a positive electrode plate can be manufactured in the following manner. The components for manufacturing the positive electrode plate, such as the positive electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is applied to a positive electrode current collector, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[0054] When the electrode plate 6 of the present application is a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer disposed on one surface of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material.

[0055] For example, the negative electrode current collector has two surfaces that face each other in the thickness direction of the negative electrode current collector, and the negative electrode active material layer is disposed on one of the two facing surfaces of the negative electrode current collector.

[0056] In some embodiments, the negative electrode current collector may be a composite current collector. The composite current collector may include a support layer made of an insulating material having a fibrous pore structure and a conductive layer formed on one surface of the support layer. The composite current collector may be formed by forming a metal material (e.g., copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a support layer (e.g., polyethylene film, polypropylene film, polyvinylidene chloride film, or a multilayer composite film thereof).

[0057] In some embodiments, the negative electrode active material may be a battery negative electrode active material well known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate. The silicon-based material may be selected from at least one of silicon elemental, silicon oxide, silicon carbon composite, silicon nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of tin elemental, tin oxide, and tin alloy. However, the present application is not limited to these materials, and other conventional materials usable as a battery negative electrode active material may also be used. These negative electrode active materials may be used alone or in combination.

[0058] In some embodiments, the negative electrode active material layer optionally further comprises an adhesive, which may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0059] In some embodiments, the negative electrode active material layer optionally further comprises a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0060] In some embodiments, the negative electrode active material layer optionally further includes other auxiliary agents, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0061] In some embodiments, a negative electrode plate can be manufactured in the following manner. The components for manufacturing a negative electrode plate, such as the negative electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry. The negative electrode slurry is applied to a negative electrode current collector, and the negative electrode plate is obtained after undergoing processes such as drying and cold pressing.

[0062] [Electrode Assembly] In one embodiment of the present application, an electrode assembly 52 is provided. The electrode assembly 52 includes a positive electrode plate (first electrode plate) 6, a negative electrode plate (second electrode plate) 7, and a separator 8 that prevents short-circuiting between the positive and negative electrodes when the electrode assembly is manufactured in a winding process and allows ions to pass through. In this specification, the positive electrode plate is referred to as the first electrode plate and the negative electrode plate is referred to as the second electrode plate, although the two may be reversed.

[0063] In some embodiments, the positive plate of the positive and negative plates is plate 6 in the above structure of the present application. The negative plate of the positive and negative plates is plate 7 in the conventional structure, but the reverse may also be true.

[0064] 5, the negative electrode plate 7 includes a negative electrode current collector 71, negative electrode active material layers 72 formed on two surfaces of the negative electrode current collector 71, and an electrical connection member 73 electrically connected to the negative electrode current collector 71. When viewed from the longitudinal direction X of the electrode plate, the support layer 611 of the positive electrode plate 6 is disposed so as to be in close contact with the negative electrode plate 7.

[0065] Fig. 6 is a plan view of the electrode assembly 52 after winding shown in Fig. 5. After winding the electrode assembly, the positive electrode active material layer of the positive electrode plate 6 is placed in close contact with the separator 8.

[0066] As a result, there is no need to place a separator between the positive electrode plate 6 and the negative electrode plate 7 in this embodiment, and the support layer 611 acts as a separator between the positive electrode plate 6 and the negative electrode plate 7. The negative electrode plate 7 and the positive electrode plate 6 are separated by the separator 8.

[0067] FIG. 7 is a cross-sectional view of an electrode assembly 52A according to an embodiment of the present application. FIG. 8 is a plan view of the electrode assembly 52A shown in FIG. 3 after winding. The electrode assembly 52A differs from the electrode assembly 52 described above in that the positive and negative electrode plates are each electrode plates having the above-described structure of the present application. That is, the negative electrode plate 6A includes a current collector 61A, an active material layer 62A disposed on one surface of the current collector 61A, and an electrical connection member 63A electrically connected to the current collector 61A. Here, the active material layer 62A is disposed on one surface of the current collector 61A via an undercoat layer 66A, but the active material layer 62A may also be disposed directly on one surface of the current collector 61A. The electrode plate 6A further includes a first insulating layer 64A disposed on another surface of the current collector 61A and covering at least the entire intermediate welding region A as viewed in the thickness direction Y of the electrode plate 6A.

[0068] 7 and 8, in this embodiment, the support layer 611 of the positive electrode plate 6 is disposed so as to be in close contact with the negative electrode active material layer 62A of the negative electrode plate 6A, and the support layer 611A of the negative electrode plate 6A is disposed so as to be in close contact with the positive electrode active material layer 62 of the positive electrode plate 6. As a result, there is no need to dispose a separator between the positive and negative electrode plates 6, 6A in this embodiment, and the support layers 611, 611A act as a separator between the positive and negative electrode plates 6, 6A.

[0069] Although the above embodiment has been described using an example in which the electrode plates are wound, it is also applicable to stacked electrode plates.

[0070] [Secondary battery] In one embodiment of the present application, there is provided a secondary battery, which includes the above-described electrode plate of the present application or the above-described electrode assembly of the present application.

[0071] The secondary battery further includes an electrolyte. During the charge and discharge process of the battery, active ions travel back and forth between the positive and negative electrodes to intercalate and deintercalate. The electrolyte serves to conduct ions between the positive and negative electrodes.

[0072] (electrolyte) The electrolyte serves to conduct ions between the positive and negative electrodes. The present application does not specifically limit the type of electrolyte, and it can be selected according to needs. For example, the electrolyte may be liquid, gel, or all solid.

[0073] In some embodiments, the electrolyte employs an electrolytic solution, the electrolytic solution including an electrolyte salt and a solvent.

[0074] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, and lithium tetrafluoro(oxalato)phosphate.

[0075] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0076] In some embodiments, the electrolyte solution optionally further includes additives. For example, the additives may include an anode film-forming additive and a cathode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves the overcharge performance of the battery or an additive that improves the high-temperature or low-temperature performance of the battery.

[0077] (separator) In some embodiments, the secondary battery may further include a separator disposed between the positive and negative electrode plates to prevent short-circuiting between the positive and negative electrodes and allow ions to pass through. However, since the support layer in the electrode plate of the present application can also function as a separator, if the positive and negative electrode plates in the secondary battery of the present application are separated by a support layer, a separate separator is not necessary. The present application does not particularly limit the type of separator, and any well-known separator with a porous structure having good chemical and mechanical stability may be selected.

[0078] In some embodiments, the separator may be made of at least one material selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer thin film or a multi-layer composite thin film, without any particular limitation. When the separator is a multi-layer composite thin film, the materials of the layers may be the same or different, without any particular limitation.

[0079] In some embodiments, the positive and negative electrode plates, and optional separators, can be fabricated into an electrode assembly by a winding or lamination process.

[0080] In some embodiments, the secondary battery may include an exterior packaging, which may be used to package the electrode assembly and electrolyte.

[0081] In some embodiments, the exterior of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The exterior of the secondary battery may be a flexible package, such as a bag-type flexible package. The flexible package may be made of plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0082] In the present application, there is no particular limitation on the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Fig. 9 shows a secondary battery 5 having a rectangular structure as an example.

[0083] In some embodiments, referring to FIG. 10 , the exterior may include a housing 51 and a cover plate 53. Here, the housing 51 may include a bottom plate and side plates connected to the bottom plate, which together form a surrounding accommodating cavity. The housing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can be provided to cover the opening and close the accommodating cavity. The positive and negative electrode plates, and an optional separator, can be formed into an electrode assembly 52 by a winding or stacking process. The electrode assembly 52 is packaged within the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. The secondary battery 5 may include one or more electrode assemblies 52, which can be selected by those skilled in the art according to actual specific needs.

[0084] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0085] [Battery module] FIG. 11 shows an example of a battery module 4. Referring to FIG. 11, in the battery module 4, a plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fastened with fasteners.

[0086] Optionally, the battery module 4 may further include a housing having a storage space for storing a plurality of secondary batteries 5.

[0087] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0088] [Battery pack] 12 and 13 show an example of a battery pack 1. Referring to FIGS. 12 and 13, the battery pack 1 may include a battery case and a plurality of battery modules 4 installed in the battery case. The battery case includes an upper case 2 and a lower case 3, and the upper case 2 is provided to cover the lower case 3 and can form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery case in any manner.

[0089] [Power consumption equipment] The present application also provides a power consuming device including at least one of a secondary battery, a battery module, or a battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile equipment (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0090] The power consumption device may be a secondary battery, a battery module, or a battery pack, depending on the requirements of the use.

[0091] 14 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, which can use a battery pack or a battery module to meet the high power and high energy density requirements of secondary batteries.

[0092] Other example devices may be mobile phones, tablet computers, laptop computers, etc. These devices are generally required to be lightweight and may employ secondary batteries as their power source.

[0093] Example The current collectors used in the electrode plates in the examples and comparative examples were manufactured as follows.

[0094] 1. Current collector manufacturing: A support layer of a certain thickness (5000 nm) was selected, and a conductive layer of a certain thickness (2000 nm) was formed on one surface by vacuum deposition, mechanical roll pressing, or adhesive bonding. A first insulating slurry was applied to the other surface and dried to obtain a first insulating layer.

[0095] where: (1) The conditions for forming the vacuum deposition method are as follows: A substrate with a cleaned surface is placed in a vacuum deposition chamber, and a high-purity metal wire in the metal evaporation chamber is melted and evaporated at high temperatures of 1300°C to 2000°C. The evaporated metal passes through a cooling system in the vacuum deposition chamber and is finally deposited on the surface of the substrate to form a conductive layer.

[0096] (2) The conditions for forming the mechanical roll press are as follows: A foil sheet of conductive layer material is placed on a mechanical roll, and a pressure of 20t to 40t is applied to roll it to a predetermined thickness. This is then placed on the surface of a support layer whose surface has been cleaned. Finally, both are placed on a mechanical roll, and a pressure of 30t to 50t is applied to tightly bond the two together.

[0097] (3) The conditions for forming the adhesive method are as follows: a foil sheet of conductive layer material is placed on a mechanical roll, and a pressure of 20t to 40t is applied to roll it to a predetermined thickness. A mixed solution of PVDF and NMP is then applied to the surface of the cleaned support layer. Finally, the conductive layer of the predetermined thickness is adhered to the surface of the support layer and dried at 100°C.

[0098] 2. Electrode plate manufacturing: 1) Positive electrode plate without conductive undercoat layer: 92 wt% of the positive electrode active material (NCM333 is used by default if no specific material is specified), 5 wt% of the conductive agent Super-P (abbreviated as "SP"), and 3 wt% of PVDF were mixed uniformly in NMP as a solvent to form a positive electrode active material layer slurry (the composition of the active material layer slurry in some examples may vary, and in such cases, the composition specified in that example will be used as the standard). The positive electrode active material layer slurry was applied in sections to one surface of the composite current collector prepared by the above method using a press coating method, and the positive electrode active material layer was obtained after drying at 85°C. The current collector with each coating layer was then cold-pressed, cut, and then dried in a vacuum at 85°C for 4 hours. A tab was then welded to obtain a positive electrode plate.

[0099] 2) Conventional positive electrode plate: The current collector was an Al foil sheet with a thickness of 12 μm. Similar to the manufacturing method of the positive electrode plate described above, the positive electrode active material layer slurry was directly applied to the surface of the Al foil sheet current collector, followed by post-treatment to obtain a conventional positive electrode plate.

[0100] 3) Positive electrode plate with conductive undercoat layer: A conductive material (e.g., conductive carbon black), an adhesive (e.g., PVDF or polyacrylic acid), and an optional active material in a certain mixing ratio (4:1) were dissolved in a suitable solvent (e.g., NMP or water) and stirred uniformly to prepare a primer slurry.

[0101] The undercoat slurry is uniformly coated on the surface of the composite current collector at a coating speed of 20 m / min, and the undercoat layer is dried in an oven at a temperature of 70-100° C. for 5 minutes.

[0102] After the undercoat layer was completely dried, 92 wt% of the positive electrode active material, 5 wt% of the conductive agent Super-P (abbreviated as "SP"), and 3 wt% of PVDF were mixed in NMP as a solvent and stirred uniformly to form a positive electrode active material layer slurry. The positive electrode active material layer slurry was applied in sections to the surface of the undercoat layer using pressure coating, and dried at 85°C to obtain a positive electrode active material layer. This was then post-treated to obtain a positive electrode plate with a conductive undercoat layer.

[0103] 4) Negative plate with conductive undercoat layer: The negative electrode active material artificial graphite, the conductive agent Super-P, the thickener CMC, and the adhesive SBR were added to the solvent deionized water in a mass ratio of 96.5:1.0:1.0:1.5 and mixed uniformly to obtain a negative electrode active material layer slurry. The negative electrode active material layer slurry was applied in sections to one surface of the composite current collector prepared by the above method using pressure application, and then dried at 85°C to obtain a negative electrode active material layer.

[0104] The current collectors having each coating layer were then cold pressed and cut, then dried at 110° C. under vacuum conditions for 4 hours, and a tab was welded to obtain a negative electrode plate.

[0105] 5) Conventional negative electrode plate: The current collector was a Cu foil sheet with a thickness of 8 μm. Similar to the manufacturing method of the negative electrode plate described above, the negative electrode active material layer slurry was directly applied to the surface of the Cu foil sheet current collector, followed by post-treatment to obtain a conventional negative electrode plate.

[0106] 6) Negative plate with conductive undercoat layer: A conductive material (e.g., conductive carbon black), an adhesive (e.g., PVDF or polyacrylic acid), and an optional active material in a certain ratio (4:1) are dissolved in a suitable solvent (e.g., NMP or water) and stirred uniformly to prepare a primer slurry.

[0107] The undercoat slurry is uniformly coated on the surface of the composite current collector at a coating speed of 20 m / min, and the undercoat layer is dried in an oven at a temperature of 70-100° C. for 5 minutes.

[0108] After the undercoat layer was completely dried, the negative electrode active material artificial graphite, conductive agent Super-P, thickener CMC, and adhesive SBR were added to the solvent deionized water in a mass ratio of 96.5:1.0:1.0:1.5 and mixed uniformly to obtain a negative electrode active material layer slurry. The negative electrode active material layer slurry was applied in sections to the undercoat layer of the current collector using pressure application, and after drying at 85°C, a negative electrode active material layer was obtained, which was then post-treated to obtain a negative electrode plate with a conductive undercoat layer in the extended region.

[0109] 3. Battery manufacturing: Using the conventional battery manufacturing process, a positive electrode plate (compaction density: 3.4 g / cm3), a negative electrode plate (compaction density: 1.6 g / cm3), and a PP / PE / PP separator (two separators, one separator, or no separator can be selected as needed) are wound together to form a bare cell, which is then placed into a battery case, and an electrolyte (EC:EMC volume ratio 3:7, LiPF6 1 mol / L) is injected. Then, sealing, chemical formation, and other processes are carried out to finally obtain a lithium-ion secondary battery (hereinafter referred to as battery).

[0110] 5. Battery test method: 1) Electrode plate wrap test: The positive and negative electrodes prepared in step 3 above were connected to the positive and negative electrodes of a battery with a capacity of 2.2 Ah and a voltage of 4.2 V, respectively, and the positive electrode was brought into direct contact with the negative electrode to observe whether sparks occurred. At the same time, multiple lapping points were selected, and the lapping method was consistent each time, thereby verifying the protective effect and observing the profile of the electrode plates.

[0111] 2) DCR (DC Internal Resistance) Test Method: According to the physical equation R=V / I, the test equipment forces a large, constant DC current (currently, a large current of 40A-80A is generally used) through the battery for a short period of time (typically 2-3 seconds), measures the voltage across the battery at this time, and calculates the current internal resistance of the battery based on the equation.

[0112] 6. Test results and discussion: 6.1 Effects of the first and second insulating layers on the safety and internal resistance of secondary batteries The following describes the effects of the first and second insulating layers on battery performance, particularly on the safety and DC internal resistance of secondary batteries, using a positive electrode plate as an example. An electrode plate was manufactured using the ingredients listed in Table 1 below, essentially according to the procedure described above in "2. Manufacture of Electrode Plates." Optionally, a second insulating slurry was applied and dried to form a second insulating layer. Finally, a battery was constructed and tested according to the procedure described above in "3. Manufacture of Battery." [Table 1] JPEG0007727000000002.jpg21949

[0113] As can be seen from Table 1, by comparing Examples 1 to 5 with Comparative Examples 1 and 2, it was found that Examples 1 to 5, which have a first insulating layer, exhibited good protective effect in the wrap test and had a DC internal resistance close to that of conventional electrodes.

[0114] Furthermore, a comparison between Example 1 and Example 6 revealed that the DC internal resistance of the secondary battery can be further reduced by further providing a second insulating layer. A comparison between Example 7 and Example 8 revealed that the DC internal resistance of the secondary battery can be further reduced by further providing an undercoat layer.

[0115] Furthermore, a comparison between Example 3 and Example 4 revealed that the protective effect in the lapping test can be further improved by overlapping the boundary between the active material layer and the first insulating layer in the X direction.

[0116] Furthermore, a comparison of Examples 8 and 11 with Examples 9 and 10 revealed that the DC internal resistance of the secondary battery can be further reduced by setting the boundary distance in the X direction between the undercoat layer and the active material layer to 1 to 3 mm.

[0117] 6.2 Effect of composite current collectors with organic support layers on the volumetric energy density of secondary batteries The influence of a composite current collector having an organic support layer on the volumetric energy density of a secondary battery will be described below with reference to Table 2. [Table 2]

[0118] As can be seen from Table 2, when a composite current collector having an organic support layer is used in one electrode plate, the volumetric energy density can be improved compared to a secondary battery using conventional positive and negative electrode plates. However, when a composite current collector having an organic support layer is used in two electrode plates, the volumetric energy density can be further improved.

[0119] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves similar functions and effects within the scope of the technical solution of the present application is considered to be within the technical scope of the present application. Furthermore, various modifications that a person skilled in the art may make to the embodiments without departing from the spirit of the present application, and other forms constructed by combining some of the components of the embodiments are also considered to be within the scope of the present application. [Explanation of symbols]

[0120] 1 battery pack, 2 upper case, 3 lower case, 4 battery module, 5 secondary battery, 51 housing, 52 electrode assembly, 53 cover plate, 6 electrode plate, 61 current collector, 611 support layer, 612 conductive layer, 62 active material layer, 63 electrical connection member, 64 first insulating layer, 65 second insulating layer, 66 undercoat layer, 7 electrode plate, 71 current collector, 72 active material layer, 73 electrical connection member, 8 separator, 52A electrode assembly, 6A electrode plate, 61A current collector, 611A support layer, 612A conductive layer, 62A active material layer, 63A electrical connection member, 64A first insulating layer, 65A second insulating layer, 66A undercoat layer.

Claims

1. An electrode plate including a current collector, an active material layer disposed on one surface of the current collector, and an electrical connection member electrically connected to the current collector; the active material layer is disposed on a main body portion of the current collector, and the electrical connection member and the current collector are welded together at an edge of the current collector, and the welded connection region is called a relay welding region; the current collector includes a support layer and a conductive layer disposed on one surface of the support layer; Here, the electrode plate further includes a first insulating layer that is disposed on another surface of the current collector and that covers at least the entire relay welding region when viewed in the thickness direction of the electrode plate, the support layer is made of an insulating material, and the insulating material has a fibrous pore structure; an undercoat layer is provided between the active material layer and the current collector; a width in the width direction of the undercoat layer that is 1 mm to 3 mm smaller than a width in the width direction of the active material layer, the width direction being perpendicular to the thickness direction, and the relay welding region being located outside an edge of the active material layer in the width direction when viewed from the thickness direction of the electrode plate.

2. 2. The electrode plate according to claim 1, wherein the support layer is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof.

3. The electrode plate according to claim 1 or 2, wherein, when viewed from the thickness direction of the electrode plate, a side surface of the first insulating layer perpendicular to the thickness direction overlaps a side surface of the active material layer perpendicular to the thickness direction.

4. The electrode plate according to claim 1 or 2, wherein the first insulating layer is made of a resin material and is made of the same material as the support layer.

5. the first insulating layer is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof; Alternatively, the first insulating layer is an adhesive or a resin material.

6. The electrode plate is installed on one surface of the electrical connection member and, when viewed in the thickness direction of the electrode plate, further includes a second insulating layer covering at least the entire relay welding area. The electrode plate according to any one of claims 1 to 5.

7. The electrode plate according to claim 6 , wherein the second insulating layer is an adhesive or a resin material.

8. 1. An electrode assembly comprising: a first electrode plate and a second electrode plate; One of the first electrode plate and the second electrode plate is the electrode plate according to any one of claims 1 to 7, an electrode assembly wherein a support layer of one of the first and second plates is positioned in intimate contact with another of the first and second plates.

9. 1. An electrode assembly comprising: a first electrode plate and a second electrode plate; The first electrode plate and the second electrode plate are each an electrode plate according to any one of claims 1 to 7, The support layer of the first electrode plate is placed in intimate contact with the active material layer of the second electrode plate, and an electrode assembly wherein the support layer of the second electrode plate is placed in intimate contact with the active material layer of the first electrode plate.

10. A secondary battery, The secondary battery comprises the electrode plate according to any one of claims 1 to 7 or the electrode assembly according to claim 8 or 9.

11. A battery module, The battery module includes the secondary battery according to claim 10 .

12. A battery pack, The battery pack includes the battery module according to claim 11 .

13. 1. A power consuming device, comprising: The power consuming device includes at least one selected from the group consisting of the secondary battery of claim 10, the battery module of claim 11, and the battery pack of claim 12.

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