Secondary battery and its manufacturing method, battery module, battery pack and power consumption device

Abstract

The present application relates to a secondary battery, comprising a positive electrode plate and a negative electrode plate, the positive electrode plate comprising a positive electrode current collector and a positive electrode film layer on two surfaces of the positive electrode current collector, the negative electrode plate comprising a negative electrode current collector and a negative electrode film layer on two surfaces of the negative electrode current collector, the negative electrode film layer comprising a reactive region disposed opposite to the positive electrode film layer and a non-reactive region not disposed opposite to the positive electrode film layer, wherein a barrier layer is disposed on the surface of the non-reactive region. The present application further relates to a manufacturing method of the secondary battery, a battery module, a battery pack and a power consuming device.

Description

[Technical Field]

[0001] The present application relates to the field of lithium battery technology, and in particular to a secondary battery and its manufacturing method, a battery module, a battery pack and a power consuming device. [Background technology]

[0002] In recent years, as the application range of lithium-ion batteries becomes wider and wider, lithium-ion batteries are widely used in energy storage power systems such as hydroelectric power, thermal power, wind power and solar power plants, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. As lithium-ion batteries have made great progress, higher requirements are also being placed on their energy density, cycle performance and safety performance.

[0003] Currently, most coating processes for negative electrodes in the industry use a continuous coating method, meaning that there are no blank areas (free substrate) at the head and tail of the negative electrode in the battery core. While the lack of blank areas offers significant advantages in the electrode production process and production capacity, continuous coating negative electrodes have many coating layers that are not directly involved in the absorption and release of lithium. This consumes a certain amount of lithium, resulting in a loss of capacity and degrading the initial efficiency, cycle performance, and storage performance of the battery core. Therefore, conventional lithium-ion batteries still need improvement in terms of initial efficiency, cycle performance, and storage performance. Summary of the Invention

[0004] The present application has been made in view of the above-mentioned problems, and its object is to provide a secondary battery having improved initial efficiency, cycle performance, and storage performance.

[0005] To achieve the above object, the present application provides a secondary battery and a manufacturing method thereof, a battery module, a battery pack, and a power consumption device.

[0006] A first aspect of the present application provides a secondary battery, the secondary battery including a positive electrode plate and a negative electrode plate, the positive electrode plate including a positive electrode current collector and a positive electrode film layer on two surfaces of the positive electrode current collector, the negative electrode plate including a negative electrode current collector and a negative electrode film layer on two surfaces of the negative electrode current collector, the negative electrode film layer including a reaction region disposed opposite the positive electrode film layer and a non-reaction region not disposed opposite the positive electrode film layer, and a barrier layer is disposed on a surface of the non-reaction region.

[0007] As a result, the present application provides a barrier layer in the non-reactive region, isolating the non-reactive region during charging and discharging of the battery core, preventing the electrolyte from infiltrating it and blocking the path for lithium ions in the reactive region to diffuse into the non-reactive region, thereby improving the initial efficiency, cycle performance, and storage performance of the secondary battery.

[0008] In any embodiment, the barrier layer is selected from a film or coating that cannot be wetted by the electrolyte, the film comprising one or more of polypropylene, polyethylene, polyester fibers, and polyvinyl chloride, and optionally one or more of cast polypropylene, uniaxially oriented polypropylene, biaxially oriented polypropylene, polyethylene, polyester fibers, and polyvinyl chloride, and further optionally polyethylene, and the coating comprising one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyamide, polyimide, polymethylmethacrylate, polyurethane, polystyrene, polyacrylic acid, polyacrylamide, polyacrylonitrile, and copolymers of the foregoing.

[0009] In one embodiment, the thickness of the barrier layer is 6 μm-40 μm, and optionally 10 μm-20 μm, and when the thickness of the barrier layer is within the predetermined range, it can ensure that the electrode plate does not undergo significant deformation and is fully compatible with the battery core.

[0010] In one embodiment, the film has adhesive properties, and the adhesive strength is greater than 20 N / m. When the adhesive strength of the film is within a predetermined range, the film can be effectively attached to the surface of the non-reacted area.

[0011] In one embodiment, a gap region is provided along the width direction of the negative electrode plate at an end of the non-reaction region close to the reaction region, and the barrier layer is provided away from the gap region and the reaction region. When the gap region is provided at the end of the non-reaction region close to the reaction region, the initial efficiency, cycle performance, and storage performance of the secondary battery can be further improved.

[0012] In one embodiment, the width of the gap region is 5 mm to 50 mm, and optionally 10 mm to 15 mm. When the width of the gap region is within the predetermined range, it can better support the formation of a barrier layer and more effectively isolate the electrolyte without affecting the processing of the electrode plate.

[0013] In one embodiment, the depth of the spacing region is equal to the thickness of the negative electrode film layer. When the depth of the spacing region is equal to the thickness of the negative electrode film layer, the electrolyte is prevented from infiltrating into the non-reacted region along the bottom negative electrode film layer, thereby preventing lithium ions from diffusing into the non-reacted region, and further improving the initial efficiency, cycle performance, and storage performance of the secondary battery.

[0014] In any embodiment, the distance between the reaction region and the side of the spacing region closest to the reaction region is 1 mm to 10 mm, and optionally 2 mm to 4 mm. When the distance between the reaction region and the side of the spacing region closest to the reaction region is within the predetermined range, the initial efficiency and cycle performance of the secondary battery can be further improved.

[0015] A second aspect of the present application further provides a method for manufacturing a secondary battery, the method comprising: Step (1) of manufacturing a positive electrode plate; Step (2) of manufacturing a negative electrode plate; Step (3) of manufacturing a separator; Step (4) of preparing an electrolyte; and (5) manufacturing a secondary battery; wherein step (2) includes providing a barrier layer on the negative electrode plate; The secondary battery includes a positive electrode plate and a negative electrode plate, the positive electrode plate including a positive electrode current collector and a positive electrode film layer on two surfaces of the positive electrode current collector, the negative electrode plate including a negative electrode current collector and a negative electrode film layer on two surfaces of the negative electrode current collector, the negative electrode film layer including a reactive region disposed opposite the positive electrode film layer and a non-reactive region not disposed opposite the positive electrode film layer, and a barrier layer is disposed on the surface of the non-reactive region.

[0016] As a result, the method of the present application uses a simple process to install a barrier layer in the non-reactive area of ​​the negative electrode plate, thereby isolating the non-reactive area and blocking the diffusion of lithium ions from the reactive area to the non-reactive area, thereby further improving the initial efficiency, cycle performance and storage performance of the secondary battery.

[0017] In either embodiment, the barrier layer is applied by a coating or lamination process; optionally, the barrier layer is applied by a lamination process.

[0018] A third aspect of the present application provides a battery module, which includes the secondary battery of the first aspect of the present application or a secondary battery manufactured by the method of the second aspect of the present application.

[0019] A fourth aspect of the present application provides a battery pack, which includes the battery module of the third aspect of the present application.

[0020] A fifth aspect of the present application provides a power consumption device, comprising at least one selected from the secondary battery of the first aspect of the present application or a secondary battery manufactured by the method of the second aspect of the present application, the battery module of the third aspect of the present application, or the battery pack of the fourth aspect of the present application.

[0021] The battery module, battery pack and power consumption device of the present application include the secondary battery of the present application, and therefore have at least the same advantages as the secondary battery. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram of a wound battery core of a secondary battery according to an embodiment of the present application. [Figure 2] 2 is a schematic development view of a negative electrode plate of a wound battery core of the secondary battery shown in FIG. 1 according to the embodiment of the present application. FIG. [Figure 3] FIG. 10 is a schematic development view of a negative electrode plate of a wound battery core of a secondary battery according to another embodiment of the present application. [Figure 4] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 5] FIG. 5 is an exploded view of the secondary battery shown in FIG. 4 according to the embodiment of the present application. [Figure 6] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 7] 1 is a schematic diagram of a battery pack according to an embodiment of the present application; [Figure 8] FIG. 8 is an exploded view of the battery pack shown in FIG. 7 according to the embodiment of the present application. [Figure 9] 1 is a schematic diagram of a power consumption device that uses a secondary battery as a power source according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the secondary battery and manufacturing method thereof, battery module, battery pack, and power consumption device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and redundant description of actually identical structures may be omitted. This is to avoid the following description becoming unnecessarily long 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.

[0024] The "ranges" disclosed herein are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the end values, and are combinable; i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are listed and maximum range values ​​of 3, 4, and 5 are listed, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all contemplated. In this application, unless otherwise specified, the numerical range "ab" represents a shorthand notation for any combination of real numbers from a to b, where a and b are both real numbers. For example, the numerical range "0-5" represents that the present specification has already listed all real numbers between "0-5," and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as 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.

[0025] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0026] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0027] Unless otherwise stated, all steps in this application may be performed in sequence or randomly, preferably in sequence. For example, a reference to a method including steps (a) and (b) means that the method may include steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, a reference to a method may include step (c), and this means that step (c) may be added to the method in any order, e.g., 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.

[0028] Unless otherwise specified, the terms "comprise" and "include" used in this application may be open-ended or closed-ended. For example, the terms "comprise" and "include" may further include or include other components not listed, or may include or include only the listed components.

[0029] 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, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0030] In a wound or stacked battery core, the negative electrode plate must completely cover the positive electrode plate, so the negative electrode plate must have a non-reactive area that is not involved in the direct absorption and desorption of lithium with the positive electrode plate. However, during charging of the battery core, lithium ions of the positive electrode plate are preferentially absorbed in the reactive area of ​​the negative electrode plate, i.e., the area facing the positive electrode plate. The potential of the reactive area of ​​the negative electrode plate gradually decreases, while the non-reactive area remains at a relatively high potential. At this time, a potential difference is formed between the non-reactive area and the reactive area of ​​the negative electrode plate. Driven by the potential difference, the lithium ions in the reactive area diffuse to the non-reactive area at a slow rate and are absorbed. However, the lithium ions absorbed in the non-reactive area are difficult to return to the positive electrode plate during discharge, resulting in irreversible lithium loss of the positive electrode plate, which ultimately deteriorates the initial efficiency, cycle performance, and storage performance of the battery core.

[0031] In this application, by providing a barrier layer in the non-reactive region of the negative electrode plate, the non-reactive region is isolated during charging and discharging of the battery core, preventing the electrolyte from infiltrating it and blocking the path for lithium ions in the reactive region to diffuse to the non-reactive region, thereby improving the initial efficiency, cycle performance, and storage performance of the secondary battery.

[0032] [Secondary battery] In one embodiment of the present application, the present application proposes a secondary battery, the secondary battery including a positive electrode plate and a negative electrode plate, the positive electrode plate including a positive electrode current collector and a positive electrode film layer on two surfaces of the positive electrode current collector, the negative electrode plate including a negative electrode current collector and a negative electrode film layer on two surfaces of the negative electrode current collector, the negative electrode film layer including a reaction region disposed opposite the positive electrode film layer and a non-reaction region not disposed opposite the positive electrode film layer, wherein a barrier layer is disposed on the surface of the non-reaction region.

[0033] Although the mechanism is not yet clear, the applicant has made an unexpected discovery that by installing a barrier layer in the non-reactive region of the negative electrode plate, the non-reactive region is isolated during charging and discharging of the battery core, preventing the electrolyte from infiltrating it. This blocks the path for lithium ions in the reactive region to diffuse to the non-reactive region, reducing the irreversible lithium loss in the positive electrode plate, thereby improving the initial efficiency, cycle performance, and storage performance of the secondary battery.

[0034] For example, in a wound-type battery core, as shown in Fig. 1, a positive electrode plate, a negative electrode plate, and a separator are wound together to form a battery core. The negative electrode plate includes a reactive region facing the positive electrode plate and a non-reactive region not facing the positive electrode plate. The non-reactive region includes an empty winding non-reactive region and a terminal non-reactive region.

[0035] Figure 2 is a schematic diagram of an expanded negative electrode plate in the wound battery core shown in Figure 1. As shown in Figures 1 and 2, the center of the negative electrode plate is a reaction region, one end of one surface (surface A) is an unwound non-reaction region, and one end of the other surface (surface B) is a terminal non-reaction region, where a barrier layer is provided in the non-reaction region.

[0036] In some embodiments, the barrier layer is selected from a film or coating that cannot be wetted by the electrolyte, the film comprising one or more of polypropylene, polyethylene, polyester fibers, and polyvinyl chloride, and optionally one or more of cast polypropylene, uniaxially oriented polypropylene, biaxially oriented polypropylene, polyethylene, polyester fibers, and polyvinyl chloride, and further optionally polyethylene, and the coating comprising one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyamide, polyimide, polymethylmethacrylate, polyurethane, polystyrene, polyacrylic acid, polyacrylamide, polyacrylonitrile, and copolymers of the foregoing.

[0037] Polyethylene (PE) film has advantages such as being odorless, non-toxic, stable at temperatures between -90°C and 100°C, resistant to acids and alkalis, resistant to organic solvents, having low water absorption, and having excellent electrical insulation properties, so the film selectively includes PE film.

[0038] In some embodiments, the polyester fibers include polyethylene terephthalate, polybutylene terephthalate.

[0039] In some embodiments, the thickness of the barrier layer is 6 μm-40 μm, and optionally 10 μm-20 μm.

[0040] In the embodiments of this application, the thickness of the barrier layer needs to be controlled. If the barrier layer is too thin, it will be easily damaged, and if it is too thick, the electrode plate will be significantly deformed. If the thickness of the barrier layer is within a predetermined range, it can be ensured that the electrode plate will not be significantly deformed and will be fully compatible with the battery core.

[0041] In some embodiments, the film has adhesive properties, with an adhesive strength greater than 20 N / m, optionally greater than 200 N / m, and even more optionally greater than 400 N / m.

[0042] In the examples of this application, the film has a certain adhesiveness; if the adhesive strength is too low, the film cannot be tightly attached to the negative electrode film layer on the negative electrode plate and is prone to tearing; if the adhesive strength of the film is greater than 20 N / m, the film adhesive strength is optionally greater than the cohesive force between the particles in the negative electrode film layer, allowing the film to be effectively attached to the surface of the non-reactive area. As long as the electrolyte can be blocked, single-sided or double-sided adhesive films can also meet this application; however, because double-sided adhesive films are thicker than single-sided adhesive films and cause greater deformation of the electrode plate, single-sided adhesive films are preferred.

[0043] In some embodiments, a spacing region is provided along the width of the negative electrode plate at an end of the non-reacted region closer to the reactive region, and a barrier layer is provided away from the spacing region and away from the reactive region.

[0044] By providing a spacing region at the end of the non-reactive region of the negative electrode plate that is close to the reactive region, it is possible to prevent the electrolyte from infiltrating into the non-reactive region after injection, thereby preventing the diffusion of lithium ions from the reactive region into the non-reactive region, and further improving the initial efficiency, cycle performance, and storage performance of the secondary battery.

[0045] 3 is a schematic development view of a negative electrode plate of a wound battery core of a secondary battery according to another embodiment of the present application. As shown in FIG. 3, the center of the negative electrode plate is a reaction region, one end of one surface (Side A) is an unwound non-reaction region, and one end of the other surface (Side B) is a terminal non-reaction region. Here, a spacing region is provided along the width direction of the negative electrode plate at the end of the non-reaction region closest to the reaction region, and a barrier layer is provided away from the spacing region and away from the reaction region. More specifically, the barrier layer is provided on the bottom surface of the spacing region, on the side surface of the spacing region close to the non-reaction region, and in the non-reaction region away from the reaction region.

[0046] In some embodiments, the width of the spacing region is 5mm-50mm, optionally 10mm-15mm.

[0047] If the gap width is too wide, it will affect the processing performance of the electrode plate, especially during the cold pressing stage, resulting in uneven compaction of the electrode plate. If the width is too narrow, it will affect the taping process of the non-reactive area in the later stage, resulting in poor tape adhesion and electrolyte seepage from the bottom. If the gap width is within the specified range, it will better support the installation of the barrier layer and more effectively isolate the electrolyte without affecting the processing of the electrode plate.

[0048] In some embodiments, the depth of the spacing region is equal to the thickness of the negative electrode film layer.

[0049] If the depth of the gap is smaller than the thickness of the negative electrode film layer, i.e., if there is a negative electrode film layer at the bottom of the gap, the electrolyte will infiltrate into the non-reacted area along the negative electrode film layer at the bottom after injection, and the diffusion of lithium ions from the reacted area to the non-reacted area will not be prevented. Therefore, the depth of the gap is equal to the thickness of the negative electrode film layer, i.e., the bottom of the gap is the current collector of the negative electrode plate.

[0050] In some embodiments, the distance between the side of the spacing region closest to the reaction region and the reaction region is 1 mm-10 mm, and optionally 2 mm-4 mm.

[0051] If the side of the spacing region closest to the reaction region is completely close to the edge of the reaction region, it will affect the safety of the battery core, and lithium deposition may occur at the edge of the reaction region if the positive and negative electrodes are slightly misaligned. If the side of the spacing region closest to the reaction region is far from the reaction region, the negative electrode film layer between them will consume lithium, which will worsen the improvement in the initial efficiency and cycle performance of the battery core. Therefore, if the distance between the side of the spacing region closest to the reaction region and the reaction region is within a specified range, the initial efficiency and cycle performance of the secondary battery can be further improved.

[0052] In one embodiment of the present application, there is provided a method for manufacturing a secondary battery, the method comprising: Step (1) of manufacturing a positive electrode plate; Step (2) of manufacturing a negative electrode plate; Step (3) of manufacturing a separator; Step (4) of preparing an electrolyte; and (5) manufacturing a secondary battery; wherein step (2) includes providing a barrier layer on the negative electrode plate; The secondary battery includes a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode film layer on two surfaces of the positive electrode current collector. The negative electrode plate includes a negative electrode current collector and a negative electrode film layer on two surfaces of the negative electrode current collector. The negative electrode film layer includes a reactive region disposed opposite the positive electrode film layer and a non-reactive region not disposed opposite the positive electrode film layer. A barrier layer is disposed on the surface of the non-reactive region.

[0053] In some embodiments, the barrier layer is applied by a coating or lamination process; optionally, the barrier layer is applied by a lamination process.

[0054] The barrier layer that prevents the infiltration of the electrolyte is very important and can be formed by two processes: coating or pasting. The coating process requires steps such as stirring, coating, and baking, and the flow is relatively complicated compared to the pasting process, so the barrier layer is preferentially formed by the pasting process.

[0055] In some embodiments, the method further includes providing a spacing region along the width of the negative electrode plate at an end of the non-reacted region of the negative electrode plate that is closer to the reacted region, the spacing region being provided by water washing, sanding, or intermittent painting.

[0056] The secondary battery, battery module, battery pack and power consuming device of the present application will be described below with reference to the appropriate drawings.

[0057] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging, active ions shuttle between the positive and negative electrodes, absorbing and releasing ions. The electrolyte functions to conduct ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits and allows ions to pass through.

[0058] [Positive electrode plate] The positive electrode plate is disposed on a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0059] For example, the positive electrode current collector has two surfaces that face each other in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two facing surfaces of the positive electrode current collector.

[0060] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0061] In some embodiments, the positive electrode active material may be any positive electrode active material 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. The present application is not limited to these materials, and other conventional materials usable as positive electrode active materials in batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, 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(NCM 333 (may be abbreviated as "LiNi") 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (may be abbreviated as "LiNi") 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as "LiNi") 0.6 Co0.2 Mn 0.2 O2(NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 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.

[0062] In some embodiments, the positive electrode membrane layer optionally further comprises an adhesive, which 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.

[0063] In some embodiments, the positive electrode film layer optionally further comprises a conductive agent, for example, the conductive agent may comprise at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0064] In some embodiments, a positive electrode plate can be manufactured in the following manner: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then coated onto a positive electrode current collector, dried, cold-pressed, and other processes to obtain a positive electrode plate.

[0065] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0066] For example, the negative electrode current collector has two surfaces that face each other in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two facing surfaces of the negative electrode current collector.

[0067] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, the metal foil sheet may be copper foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer base (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0068] In some embodiments, the negative electrode active material may be a battery negative electrode active material 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 silicone-based material, a tin-based material, and lithium titanate. The silicone-based material may be selected from at least one of a silicone element, a silicone oxide, a silicone carbon composite, a silicone nitrogen composite, and a silicone alloy. The tin-based material may be selected from at least one of a tin element, a tin oxide, and a tin alloy. The present application is not limited to these materials, and other conventional materials usable as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination.

[0069] In some embodiments, the negative electrode membrane 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).

[0070] In some embodiments, the negative electrode film 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.

[0071] In some embodiments, the negative electrode membrane layer optionally further comprises other additives, such as a thickener (eg, carboxymethylcellulose sodium (CMC-Na)).

[0072] In some embodiments, the negative electrode plate can be manufactured in the following manner: Components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then coated onto a negative electrode current collector, dried, cold-pressed, and the like, to obtain a negative electrode plate.

[0073] [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.

[0074] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0075] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0076] 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.

[0077] In some embodiments, the electrolyte solution may further optionally contain additives, such as additives for forming a negative electrode film or a positive electrode film, and may further include additives that can improve some battery performance, such as additives for improving the overcharge performance of the battery or additives for improving the high-temperature or low-temperature performance of the battery.

[0078] [Separator] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0079] In some embodiments, the separator may be made of at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0080] In some embodiments, the positive and negative electrodes and separators can be fabricated into an electrode assembly (battery core) by a winding or lamination process.

[0081] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and electrolyte.

[0082] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0083] The present application does not particularly limit the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 4 shows an example of a rectangular secondary battery 5.

[0084] In some embodiments, referring to FIG. 5 , the exterior body may include a case 51 and a top cover assembly 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, which together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the top cover assembly 53 can be installed to cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged within the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and this can be selected by those skilled in the art according to specific actual needs.

[0085] 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, with the specific number being selectable by those skilled in the art depending on the application and capacity of the battery module.

[0086] Fig. 6 shows an example of a battery module 4. Referring to Fig. 6, 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 fixed with fasteners.

[0087] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0088] In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, the specific number of which can be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0089] 7 and 8 show an example of a battery pack 1. Referring to FIGS. 7 and 8, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be provided with a lid on the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0090] The present application also provides a power consuming device, the 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 devices (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, satellites, energy storage systems, etc.

[0091] The power consumption device can be selected from a secondary battery, a battery module, or a battery pack depending on its usage needs.

[0092] 9 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. To meet the demand for high power and high energy density from secondary batteries in the power consuming device, a battery pack or battery module can be employed.

[0093] Other examples of the device may be a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be thin and can use a secondary battery as a power source.

[0094] Example The following examples of the present application are described. The examples described below are illustrative and are used only to interpret the present application, and should not be understood as limitations on the present application. If specific techniques or conditions are not specified in the examples, they will be carried out according to the techniques or conditions described in literature in the field or according to product specifications. If the manufacturer of the reagents or equipment used is not specified, they are all commercially available ordinary products.

[0095] Example 1 (1) Manufacturing of positive electrode plates The positive electrode active material, lithium iron phosphate, the conductive agent, acetylene black, and the adhesive, polyvinylidene fluoride (PVDF), were mixed in a mass ratio of 96:2:2, and the solvent, N-methylpyrrolidone (NMP), was added. The mixture was stirred using a vacuum mixer until the system became uniform, yielding a positive electrode slurry. The positive electrode slurry was then uniformly coated on both surfaces of a 12 μm thick aluminum foil positive electrode current collector, dried at 115°C for 15 minutes, and cold pressed to obtain a positive electrode film layer with a thickness of 84 μm on each side. This was then slit to obtain a positive electrode plate with a length of 605 mm and a film width of 88 mm, with a coating weight of 20 mg / cm. 2 and the compaction density is 2.4 g / cm 3 is.

[0096] (2) Manufacturing of negative electrode plates The negative electrode active material, artificial graphite, the conductive agent, acetylene black, the thickener, carboxymethylcellulose sodium (CMC-Na), and the adhesive, SBR, were mixed in a mass ratio of 96.4:1:1.2:1.4, and deionized water was added as a solvent. The mixture was stirred using a vacuum mixer until the system was homogeneous, yielding a negative electrode slurry. The negative electrode slurry was then uniformly coated on both surfaces of an 8 μm thick negative electrode current collector copper foil, dried at 115°C for 15 minutes, and cold pressed to obtain a negative electrode film layer with a thickness of 61 μm on each side. The negative electrode plate was then slit to obtain a negative electrode plate with a length of 735 mm and a film width of 93 mm. The coating weight of the negative electrode plate was 9.4 mg / cm. 2 and the compaction density is 1.55 g / cm 3 The negative electrode plate includes a reactive region facing the positive electrode film layer and a non-reactive region not facing the positive electrode film layer (i.e., an unwound non-reactive region and a terminal non-reactive region), and a single-sided adhesive polyethylene film is attached to the non-reactive region of the negative electrode plate as a barrier layer, with an adhesive strength of 470 N / m and a thickness of 20 μm.

[0097] (3) Electrolyte production Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Thoroughly dried lithium salt LiPF6 was dissolved in the organic solvent, and the lithium salt concentration was 1 mol / L. The mixture was mixed uniformly to obtain an electrolyte solution.

[0098] (4) Separator manufacturing A polyethylene film with a thickness of 12 μm was selected as the separator.

[0099] (5) Secondary battery manufacturing The positive electrode plate, separator, and negative electrode plate were stacked in this order, with the separator positioned between the positive and negative electrodes to act as an insulator, and then wound up to obtain a bare battery core. The bare battery core was placed in an outer casing, dried, and then injected with electrolyte at an injection rate of 4.2 g / Ah. After vacuum packaging, standing, chemical formation, shaping, and other processes, a secondary battery with a capacity of approximately 3 Ah was obtained.

[0100] Example 2-3 The secondary battery was manufactured in accordance with Example 1, except that in the manufacture of the negative electrode plate, a single-sided adhesive polyethylene film was attached to the non-reactive area of ​​the negative electrode plate as a barrier layer, with an adhesive strength of 450 N / m and thicknesses of 6 μm and 40 μm, respectively.

[0101] Examples 4-6 The secondary battery was manufactured in accordance with Example 1, except that in the manufacture of the negative electrode plate, the single-sided adhesive polyethylene film was replaced with a single-sided adhesive uniaxially oriented polypropylene film, a polyethylene terephthalate film, and a polyvinyl chloride film, respectively.

[0102] Example 7 The secondary battery was manufactured in the same manner as in Example 1, except that in the manufacture of the negative electrode plate, the non-reactive area of ​​the negative electrode plate was coated with polytetrafluoroethylene as a barrier layer with a thickness of 20 μm.

[0103] Example 8 The secondary battery was manufactured in the same manner as in Example 1, except that in the manufacture of the negative electrode plate, the non-reacted area of ​​the negative electrode plate was coated with polymethyl methacrylate as a barrier layer with a thickness of 20 μm.

[0104] Example 9 The secondary battery was generally manufactured with reference to Example 1, with the difference being that in the manufacture of the negative electrode plate, a spacing region was installed along the width direction of the negative electrode plate at the end of the non-reaction region of the negative electrode plate close to the reaction region, and the spacing region was formed by removing the negative electrode film layer by grinding, with a width of 15 mm and a depth equal to the thickness of the negative electrode film layer, i.e., 61 μm. The distance between the side close to the reaction region and the reaction region was 4 mm, and a barrier layer was installed in the spacing region, spaced apart from the reaction region.

[0105] Examples 10-11 The secondary battery was manufactured in the same manner as in Example 9, except that the width of the gap region was 5 mm and 50 mm, respectively.

[0106] Example 12 The secondary battery was fabricated in the same manner as in Example 9, except that the depth of the gap region was 20 μm, that is, the negative electrode film layer in the gap region was not completely removed.

[0107] Examples 13-17 The secondary battery was manufactured in the same manner as in Example 9, except that the distance between the side of the gap region closer to the reaction region and the reaction region was 0 mm, 1 mm, 2 mm, 10 mm, and 13 mm, respectively.

[0108] Comparative Example 1 The secondary battery was manufactured in the same manner as in Example 1, except that no barrier layer was provided in the non-reactive region in the manufacture of the negative electrode plate.

[0109] Secondary battery performance test 1. Initial efficiency of secondary batteries The capacity measured after charging at 0.02C for 10 hours at 45°C is C0, and the capacity measured after charging to 3.65V at 0.33C at 25°C and then reducing the voltage to 0.05C at 3.65V is C1, and the capacity measured after finally discharging to 2.5V at 0.33C is D0. D0 / (C0+C1)×100% is the initial coulombic efficiency (initial efficiency) of the secondary battery.

[0110] 2. Storage performance of secondary batteries The secondary battery was stored at 45°C at 100% SOC (state of charge), and data was collected every 15 days for the first 60 days. After 60 days, data was collected every 30 days until the capacity had decayed to 80%, and the number of days of storage was recorded.

[0111] 3. Cycle performance of secondary batteries At 45°C, the secondary battery was charged to 3.65 V at 1 C, then the voltage was reduced to 0.05 C at 3.65 V, and the battery was discharged to 2.5 V at 1 C. These steps were repeated to perform a full charge-discharge cycle test until the capacity of the secondary battery decreased to 80% of the initial capacity, and the number of cycles was recorded.

[0112] The secondary batteries obtained in the above examples and comparative examples according to the above process were tested, and the specific values ​​are shown in Table 1.

[0113] [Table 1]

[0114] As can be seen from Table 1, the initial efficiency, storage days when the capacity is 80%, and number of cycles when the capacity retention rate is 80% of the secondary batteries of all the above examples are all higher than those of the secondary batteries of the comparative examples.

[0115] Comparing Examples 1 to 8 comprehensively, compared to Comparative Example 1, by providing a barrier layer in the non-reactive region of the negative electrode plate, the initial efficiency, storage performance, and cycle performance of the secondary battery can be clearly improved.

[0116] Comprehensive comparison of Example 1 with Examples 9 to 17 shows that when a gap region is provided at the end of the non-reaction region of the negative electrode plate that is close to the reaction region, the initial efficiency, storage performance, and cycle performance of the secondary battery can be further improved.

[0117] Comprehensively comparing Example 9 and Example 12, when the depth of the gap region is equal to the thickness of the negative electrode film layer, the initial efficiency, storage performance and cycle performance of the secondary battery can be further improved.

[0118] Comparing Example 9 with Examples 13 to 17, we found that the initial efficiency, storage performance, and cycle performance of the secondary battery could be further improved when the distance between the side of the spacing region closest to the reaction region and the reaction region was 1 mm to 10 mm. When the distance between the side of the spacing region closest to the reaction region and the reaction region was 0 mm, the initial efficiency, storage performance, and cycle performance of the secondary battery were all good. However, if the side of the spacing region closest to the reaction region was completely close to the edge of the reaction region, slight misalignment of the positive and negative electrodes could cause lithium deposition at the edge of the reaction region, which would affect the safety of the battery core. Therefore, the distance between the side of the spacing region closest to the reaction region and the reaction region should be greater than 0 mm.

[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 the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments without departing from the spirit of the present application, and other methods configured by combining some of the components of the embodiments, are also included within the scope of the present application. [Explanation of symbols]

[0120] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 secondary battery, 51 case, 52 electrode assembly, 53 top cover assembly

Claims

1. A secondary battery comprising a positive electrode plate and a negative electrode plate, the positive electrode plate comprising a positive electrode current collector and a positive electrode film layer on two surfaces of the positive electrode current collector, the negative electrode plate comprising a negative electrode current collector and a negative electrode film layer on two surfaces of the negative electrode current collector, the negative electrode film layer comprising a reactive region facing the positive electrode film layer and a non-reactive region not facing the positive electrode film layer, wherein a barrier layer is provided only on the surface of the non-reactive region, and the thickness of the barrier layer is 6 μm-40 μm.

2. 2. The secondary battery according to claim 1, wherein the barrier layer is selected from a film or coating that cannot be wetted by the electrolyte, the film comprising one or more of polypropylene, polyethylene, polyester fiber, and polyvinyl chloride, and optionally one or more of cast polypropylene, uniaxially oriented polypropylene, biaxially oriented polypropylene, polyethylene, polyester fiber, and polyvinyl chloride, and further optionally polyethylene, and the coating comprising one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyamide, polyimide, polymethyl methacrylate, polyurethane, polystyrene, polyacrylic acid, polyacrylamide, polyacrylonitrile, and copolymers of the above materials.

3. 2. The secondary battery according to claim 1, wherein a spacing region is provided along the width direction of the negative electrode plate at an end of the non-reaction region of the negative electrode plate that is close to the reaction region, and the barrier layer is provided away from the spacing region and away from the reaction region, and the spacing region is a region formed by removing the negative electrode film layer.

4. 4. The secondary battery according to claim 3, wherein the width of the gap region is 5 mm to 50 mm.

5. The secondary battery according to claim 3 , wherein the depth of the gap region is equal to the thickness of the negative electrode film layer.

6. 4. The secondary battery according to claim 3, wherein the distance between the reaction area and the side of the gap area closer to the reaction area is 1 mm to 10 mm.

7. A method for manufacturing a secondary battery, Step (1) of manufacturing a positive electrode plate; Step (2) of manufacturing a negative electrode plate; Step (3) of manufacturing a separator; Step (4) of preparing an electrolyte; (5) manufacturing a secondary battery; wherein step (2) includes providing a barrier layer on the negative electrode plate; the secondary battery includes a positive electrode plate and a negative electrode plate, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer on both surfaces of the positive electrode current collector, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer on both surfaces of the negative electrode current collector, the negative electrode film layer includes a reaction region facing the positive electrode film layer and a non-reaction region not facing the positive electrode film layer, a barrier layer is provided only on the surface of the non-reaction region, and the thickness of the barrier layer is 6 μm-40 μm.

8. The method of claim 7 , wherein the barrier layer is applied by a coating or pasting process.

9. A battery module comprising the secondary battery according to claim 1 .

10. A battery pack comprising the battery module according to claim 9.

11. A power consuming device comprising at least one selected from the group consisting of the secondary battery according to any one of claims 1 to 6, the battery module according to claim 9, and the battery pack according to claim 10.

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