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

Abstract

The present application provides a secondary battery (5), 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 both surfaces of the positive electrode current collector, the negative electrode plate comprising 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 comprising a reactive region facing the positive electrode film layer and a non-reactive region not facing the positive electrode film layer, wherein a lithium supplement layer and a barrier layer are provided in the non-reactive region. The present application further provides a manufacturing method for the secondary battery (5), a battery module (4), a battery pack (1) 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] After the battery begins charging, lithium ions from the positive electrode plate are preferentially absorbed into the reactive region of the negative electrode plate, causing a drop in the potential of the reactive region and creating a voltage difference with the non-reactive region. The lithium ions from the reactive region diffuse to the non-reactive region at a slow rate and are absorbed there. However, the lithium ions absorbed in the non-reactive region have difficulty returning to the positive electrode plate during discharge, resulting in irreversible lithium loss from the positive electrode plate and deteriorating the initial efficiency, cycle performance, and storage performance of the battery core. Therefore, conventional lithium-ion batteries require improvement in terms of initial efficiency, cycle performance, and storage performance. Summary of the Invention [Problem to be solved by 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. [Means for solving the problem]

[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 to the positive electrode film layer and a non-reaction region not disposed opposite to the positive electrode film layer, and a lithium supplement layer and a barrier layer are disposed in the non-reaction region.

[0007] The present application provides a lithium supply layer and a barrier layer in the non-reactive region of the negative electrode plate, so that the lithium supply layer effectively prevents lithium ions in the reactive region from diffusing to the non-reactive region and being absorbed. During discharge of the battery core, lithium in the lithium supply layer diffuses to the reactive region at a slow rate, but the barrier layer completely isolates the non-reactive region outside the lithium supply layer, preventing the electrolyte from infiltrating it. This completely blocks the path for the lithium in the reactive region and the lithium in the lithium supply layer to diffuse to the non-reactive region, thereby reducing the loss of the lithium source and further improving the initial efficiency, cycle performance and storage performance of the secondary battery.

[0008] In either embodiment, the lithium replenishment layer is disposed at the end of the non-reaction region closer to the reaction region, and the barrier layer is disposed away from the lithium replenishment layer and away from the reaction region, thereby improving lithium replenishment efficiency without affecting production capacity.

[0009] In any embodiment, the distance between the reaction region and the side of the lithium supply layer closest to the reaction region is 2 mm to 5 mm. When the distance between the reaction region and the side of the lithium supply layer closest to the reaction region is within a predetermined range, the initial efficiency and cycle performance of the secondary battery can be further improved.

[0010] In any of the embodiments, the lithium supplement layer includes a material capable of providing active lithium, and optionally includes one or more of metallic lithium foil, lithium powder, and lithium alloy, and further optionally includes one or more of metallic lithium foil, lithium powder, silicon lithium alloy, aluminum lithium alloy, magnesium lithium alloy, and tin lithium alloy.

[0011] In any embodiment, the theoretical capacity C of lithium in the lithium replenishment layer Li is 20%C1≦C Li ≦120%C1, optionally 90%C1≦C Li ≦120% C1, where C1 is the capacity of the negative electrode film layer corresponding to the lithium replenishment layer. Li When the above condition is satisfied, the initial efficiency, cycle performance and storage performance of the secondary battery can be improved without affecting the safety performance of the secondary battery.

[0012] 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, optionally comprising one or more of cast polypropylene, uniaxially oriented polypropylene, biaxially oriented polypropylene, polyethylene, polyester fibers, and polyvinyl chloride, further optionally comprising 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.

[0013] In any embodiment, the thickness of the barrier layer is 6 μm to 40 μm, and optionally 10 μm to 20 μm. When the thickness of the barrier layer is within the predetermined range, it can be ensured that the electrode plate does not deform significantly and is fully compatible with the battery core.

[0014] In either 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.

[0015] In any embodiment, a spacer region is provided on the negative electrode plate on a side of the lithium supplement layer away from the reaction region, along the width direction of the negative electrode plate, and the barrier layer is provided away from the spacer region and the reaction region. When a spacer region is provided on the negative electrode plate on a side of the lithium supplement layer away from the reaction region, the initial efficiency, cycle performance, and storage performance of the secondary battery can be further improved.

[0016] In any 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.

[0017] In any 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 diffusion of lithium ions into the non-reacted region, and further improving the initial efficiency, cycle performance, and storage performance of the secondary battery.

[0018] 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 a step of providing a lithium supplementary layer and 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 lithium supplement layer and a barrier layer are disposed in the non-reactive region.

[0019] In either embodiment, the barrier layer is applied by a coating or lamination process; optionally, the barrier layer is applied by a lamination process.

[0020] 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.

[0021] A fourth aspect of the present application provides a battery pack, which includes the battery module of the third aspect of the present application.

[0022] A fifth aspect of the present application provides a power consumption device, the power consumption device including 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.

[0023] 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]

[0024] [Figure 1] 1 is a structural schematic diagram of a wound battery core of a secondary battery according to an embodiment of the present application; [Figure 2] 1 is a structural schematic diagram of a stacked battery core of a secondary battery according to an embodiment of the present application; [Figure 3]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 4] 1 is a structural principle diagram of a battery core of a secondary battery according to an embodiment of the present application; [Figure 5] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 6] FIG. 6 is an exploded view of the secondary battery shown in FIG. 5 according to the embodiment of the present application. [Figure 7] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 8] 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 9] FIG. 9 is an exploded view of the battery pack shown in FIG. 8 according to an embodiment of the present application. [Figure 10] 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

[0025] 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.

[0026] 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 arbitrarily combinable; i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed 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 are listed, and maximum range values ​​of 3, 4, and 5 are listed, the ranges of 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all contemplated. In this application, unless otherwise specified, a numerical range "a to b" is a shorthand notation for any combination of real numbers 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.

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

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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).

[0032] In a wound or stacked battery core, the negative electrode plate must completely cover the positive electrode plate, so the negative electrode plate has a reactive region facing the positive electrode plate and a non-reactive region not facing the positive electrode plate. After the battery starts charging, lithium ions from the positive electrode plate are preferentially absorbed into the reactive region of the negative electrode plate, causing the potential of the reactive region of the negative electrode plate to decrease, forming a voltage difference with the non-reactive region. Driven by the voltage difference, the lithium ions from the reactive region are slowly diffused to and absorbed in the non-reactive region. However, the lithium ions absorbed in the non-reactive region are less likely to return to the positive electrode plate during discharge, resulting in irreversible lithium loss from the positive electrode plate, ultimately deteriorating the initial efficiency, cycle performance, and storage performance of the battery core.

[0033] In this application, by providing a lithium supply layer in the non-reaction region of the negative electrode plate, the initial efficiency, cycle performance and storage performance of the secondary battery can be improved; by providing a barrier layer in the non-reaction region of the negative electrode plate, the penetration of the electrolyte can be prevented, and the lithium supply layer and the reaction region can block the path for lithium ions to diffuse into the non-reaction region, thereby increasing the lithium supply efficiency and further improving the initial efficiency, cycle performance and storage performance of the secondary battery.

[0034] [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 to the positive electrode film layer and a non-reaction region not disposed opposite to the positive electrode film layer, wherein a lithium supplement layer and a barrier layer are disposed in the non-reaction region.

[0035] Although the mechanism is not yet clear, according to the applicant's unexpected discovery, the present application provides a lithium supply layer and a barrier layer in the non-reactive region of the negative electrode plate, so that the lithium supply layer effectively prevents lithium ions in the reactive region from diffusing to the non-reactive region and being absorbed. During discharge of the battery core, the lithium ions in the lithium supply layer diffuse to the reactive region at a slow rate, but the barrier layer completely isolates the non-reactive region outside the lithium supply layer, preventing the electrolyte from infiltrating it. This completely blocks the path for the reactive region and the lithium ions in the lithium supply layer to diffuse to the non-reactive region, thereby reducing the loss of the lithium source and further improving the initial efficiency, cycle performance and storage performance of the secondary battery.

[0036] In an embodiment of the present application, the secondary battery further includes a separator. The positive electrode plate, the negative electrode plate and the separator are wound or stacked to form a battery core.

[0037] The two surfaces of the negative electrode plate are designated as side A and side B, respectively. In a wound battery core, the negative electrode plate must completely cover the positive electrode plate, as shown in Figure 1. To satisfy this requirement, a non-reactive region is formed in the central region by one or more cycles of idle winding, which is defined in this application as the idle winding non-reactive region of side A. Similarly, to satisfy the requirement that the negative electrode plate completely covers the positive electrode plate, there is a non-reactive region of one or more cycles outside the negative electrode plate in the terminal region, which is defined in this application as the terminal non-reactive region of side B.

[0038] As shown in FIG. 2, in the stacked battery core, the outermost layer of the negative electrode plate is a non-reactive region.

[0039] Fig. 3 is a schematic development view of the negative electrode plate in the wound-type battery core shown in Fig. 1. As shown in Fig. 1 and Fig. 3, a lithium supply layer and a barrier layer are provided in the non-reaction region of the unwound electrode on surface A and the terminal non-reaction region on surface B, respectively.

[0040] In the stacking process, there is no non-reacted region in the center of the battery core, and only the outermost layer of the battery core has a non-reacted region, but in the winding process, there are non-reacted regions in both the center and the tail of the battery core, and the more sites in the non-reacted region, the more advantageous it is for allocating the lithium supply layer, so the battery core is optionally a wound type battery core.

[0041] 4 is a structural principle diagram of a secondary battery according to an embodiment of the present application. As shown in FIG. 4, in the present application, before injection, a lithium source is placed on the surface of the negative electrode film layer in the non-reaction region to form a lithium supplementary layer. The standard electrode potential of lithium with respect to hydrogen is −3.05 V, and the standard electrode potential of a lithium-non-occluding negative electrode active material, such as graphite or silicon carbon material, with respect to hydrogen is about 0 V. Therefore, there is a voltage difference of about 3 V between the lithium and the negative electrode active material, such as graphite or silicon carbon material, and after injection of the battery core, the lithium source and the negative electrode film layer are in close contact with each other, forming an electric circuit, which corresponds to a direct short-circuit state (in this state, the lithium source is the negative electrode and the negative electrode film layer is the positive electrode). Due to the action of this voltage difference, the lithium in the lithium source loses electrons and turns into freely mobile lithium ions, which are absorbed into the negative electrode film layer, for example, LiC x (x≧6) or / and Li x Si y (x>0, y>0), etc., are formed, and at this time, the original lithium source, LiC x or / and Li x Si y The lithium supply layer is combined to form a new, stable lithium supply layer. The potential of the lithium supply layer is reduced, which can effectively prevent lithium ions from diffusing to the non-reaction area for absorption. The lithium supply layer is always at a relatively low potential. During the discharge of the battery core, when the potential of the reaction area of ​​the negative electrode plate gradually increases, the potential of the reaction area becomes much higher than that of the non-reaction area, and the lithium in the lithium supply layer is driven by this potential difference to diffuse to the reaction area at a slower rate, thereby improving the initial efficiency, cycle performance, and storage performance of the secondary battery.

[0042] The lithium ions in the lithium supply layer not only diffuse into the reaction region under the action of the voltage difference, but also are absorbed in the non-reaction region outside the lithium supply layer under the action of the voltage difference. The present application installs a barrier layer in the non-reaction region, completely isolating the non-reaction region outside the lithium supply layer, so that the electrolyte cannot infiltrate it, completely blocking the path for the lithium ions in the lithium supply layer and the reaction region to diffuse into the non-reaction region, thereby reducing the loss of the lithium source and further improving the initial efficiency, cycle performance and storage performance of the secondary battery.

[0043] In some embodiments, the lithium replenishment layer is installed at the end of the non-reaction region close to the reaction region, and the barrier layer is installed away from the edge of the lithium replenishment layer, away from the reaction region. If the lithium replenishment layer is installed away from the reaction region and located in the central region of the non-reaction region, the relative diffusion path of lithium ions becomes longer, reducing the lithium replenishment efficiency and making it inconvenient to install the barrier layer, affecting production capacity.

[0044] In some embodiments, the distance between the side of the lithium supply layer closest to the reaction region and the reaction region is 2 mm to 5 mm. The lithium supply layer must maintain a certain distance from the reaction region to prevent a slight misalignment of the positive and negative electrode plates during winding that could cause a portion of the lithium supply layer to enter the reaction region and pose a serious safety risk. The lithium in the lithium supply layer will diffuse to the surroundings after injection. If the distance to the reaction region is too close, excessive lithium absorption in the reaction region close to the lithium supply layer may induce lithium deposition, which could cause a battery short circuit. Maintaining a distance of 2 mm or more can avoid the above risks, but the distance cannot be too far. If the distance is too far, too much lithium source will be consumed and the lithium supply effect will be reduced. Therefore, a distance of 5 mm or less is most effective.

[0045] In some embodiments, the lithium supply layer comprises a material capable of providing active lithium, optionally including one or more of metallic lithium foil, lithium powder, and lithium alloy, and further optionally including one or more of metallic lithium foil, lithium powder, silicon lithium alloy, aluminum lithium alloy, magnesium lithium alloy, and tin lithium alloy.

[0046] Lithium alloys have a relatively low gram capacity and generate metal impurities after lithium release, while metallic lithium itself has a high gram capacity and generates no impurities after reaction. The processing performance of lithium foil in metallic lithium is superior to that of lithium powder, so the lithium supplement layer optionally includes metallic lithium foil.

[0047] In some embodiments, the theoretical capacity C of lithium in the lithium replenishment layer Li is 20%C1≦C Li ≦120%C1, optionally 90%C1≦C Li ≦120% C1, where C1 is the capacity of the negative electrode film layer corresponding to the lithium supplementary layer.

[0048] The ratio of the capacity of the lithium supply layer to the capacity of the negative electrode film layer corresponding to the lithium supply layer below the lithium supply layer affects the lithium supply effect and the safety of the battery core. Li <20%C1, V Li >V 負 (V Li is the potential of the lithium replenishment layer, and V 負 is the lithium absorption plateau voltage of the negative electrode plate), that is, the potential of the lithium supplementary layer is higher than the lithium absorption plateau voltage of the negative electrode plate, so that lithium in the lithium supplementary layer cannot be absorbed into the lithium absorption region, and lithium in the lithium absorption region cannot be prevented from diffusing into the lithium supplementary layer. Li If C1 is >120%, V Li <V 負 and

number

[0049] In the wound-type battery core, the lithium supply layer may be disposed in the non-reacted area on the surface A of the battery core and / or in the terminal non-reacted area on the surface B of the battery core, and C Li =C A +C B and C A is the theoretical capacity of lithium in the lithium supply layer installed in the unwound non-reactive area on the A side of the battery core, and C B is the theoretical capacity of lithium in the lithium supply layer installed in the terminal non-reaction area on the B side of the battery core. Li ≦C A ≦100%C Li , 0%C Li ≦C B ≦100%C Li and C A and C BIf these are not zero at the same time, the initial efficiency, cycle performance, and storage performance of the secondary battery can be further improved. Since the ability to retain the electrolyte in the center of the battery core is relatively strong and it is also favorable for the diffusion of lithium ions in the lithium source, selectively C A >C B is.

[0050] Lithium replenishment layer weight per unit area = (coating weight of negative electrode film layer × weight ratio of negative electrode active material × gram capacity of negative electrode active material) × (C Li / C1) / Theoretical capacity of lithium in the lithium supplement layer. For example, the lithium supplement layer is made of lithium foil, and the coating weight of the negative electrode film layer is 9.4 mg / cm 2 The negative electrode active material is artificial graphite, and the weight ratio of the negative electrode active material to the negative electrode film layer is 96%. Li = 100% C1, lithium foil weight per unit area = (9.4 × 96% × 360) × 100% / 3860 = 0.84 mg / cm 2 where the gram capacity of the synthetic graphite is 360 mAh / g and the theoretical capacity of lithium metal is 3860 mAh / g. A rolling machine can be used to obtain different lithium replenishment layer weights per unit area.

[0051] 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, optionally comprising one or more of cast polypropylene, uniaxially oriented polypropylene, biaxially oriented polypropylene, polyethylene, polyester fibers, and polyvinyl chloride, further optionally comprising 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.

[0052] 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.

[0053] In some embodiments, the polyester fibers include polyethylene terephthalate, polybutylene terephthalate.

[0054] In some embodiments, the thickness of the barrier layer is between 6 μm and 40 μm, and optionally between 10 μm and 20 μm.

[0055] 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 certain range, it can be ensured that the electrode plate will not be significantly deformed and will be fully compatible with the battery core.

[0056] In some embodiments, the film has adhesive properties, with an adhesive force greater than 20 N / m, optionally greater than 200 N / m, and even more optionally greater than 400 N / m.

[0057] 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, it can be effectively attached to the surface of the non-reactive area, and optionally the adhesive strength of the film is greater than the cohesive force between particles in the negative electrode film layer. As long as it can block the electrolyte, 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.

[0058] In some embodiments, a spacer region is provided on the negative electrode plate on the side of the lithium supplement layer away from the reaction region along the width direction of the negative electrode plate, and a barrier layer is provided on the spacer region away from the reaction region. More specifically, the barrier layer is provided on the bottom surface of the spacer region, on the side of the spacer region near the non-reaction region, and on the non-reaction region away from the reaction region.

[0059] By providing a spacing region on the negative electrode plate away from the reaction region of the lithium supply layer, it is possible to prevent the electrolyte from infiltrating into the non-reaction region after injection, thereby preventing the lithium ions from the lithium supply layer and the reaction region from diffusing into the non-reaction region, and further improving the initial efficiency, cycle performance, and storage performance of the secondary battery.

[0060] In some embodiments, the width of the spacing region is between 5 mm and 50 mm, optionally between 10 mm and 15 mm.

[0061] 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.

[0062] In some embodiments, the depth of the spacing region is equal to the thickness of the negative electrode film layer.

[0063] 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-reaction area along the negative electrode film layer at the bottom after injection, and the lithium ions from the lithium supplement layer and the reaction area cannot be prevented from diffusing into the non-reaction area. 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.

[0064] 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 lithium supplementary layer and a barrier layer on a 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 lithium supplement layer and a barrier layer are disposed in the non-reactive region.

[0065] In some embodiments, the barrier layer is applied by a coating or lamination process; optionally, the barrier layer is applied by a lamination process.

[0066] 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.

[0067] The lithium supplement layer may be applied by processes such as lamination, roll pressing, painting, and the like.

[0068] In some embodiments, the method further includes providing a spacing region on the negative electrode plate, away from the reaction region of the lithium supplementary layer, along the width of the negative electrode plate, the spacing region being provided by solvent washing, grinding, or intermittent coating.

[0069] 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.

[0070] 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 them. The electrolyte functions to conduct ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short-circuiting and allows ions to pass through.

[0071] [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.

[0072] 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.

[0073] 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)).

[0074] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries 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 that can be used 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. 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 Co 0.2 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 0.05Examples 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.

[0075] In some embodiments, the positive electrode membrane layer optionally further includes 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.

[0076] In some embodiments, the positive electrode film layer may further optionally include a conductive agent, for example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0077] 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, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[0078] [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.

[0079] 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.

[0080] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, a copper 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 material. 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 material (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0081] 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, silicon-based materials, tin-based materials, 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. 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.

[0082] 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).

[0083] In some embodiments, the negative electrode film layer further optionally includes 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.

[0084] In some embodiments, the negative electrode membrane layer further optionally includes other auxiliary agents, such as a thickener (e.g., carboxymethylcellulose sodium (CMC-Na)).

[0085] 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 other processes to obtain a negative electrode plate.

[0086] [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.

[0087] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0088] 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.

[0089] 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.

[0090] In some embodiments, the electrolyte solution further optionally contains additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode 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.

[0091] [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.

[0092] 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.

[0093] 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.

[0094] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0095] 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.

[0096] 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 5 shows an example of a rectangular secondary battery 5.

[0097] In some embodiments, referring to FIG. 6, the exterior body comprises a case 51 and Top Cover Assembly The case 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate form a surrounding storage cavity. The case 51 has an opening communicating with the storage cavity, Top Cover Assembly 53A cover can be placed on the opening to seal the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator can be wound or stacked to form an electrode assembly 52. ​​The electrode assembly 52 is packaged in the receiving cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 can be one or more, and can be selected by those skilled in the art according to specific actual needs.

[0098] In some embodiments, the secondary battery 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 can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0099] FIG. 7 shows an example of a battery module 4. Referring to FIG. 7, 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.

[0100] 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.

[0101] 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.

[0102] 8 and 9 show an example of a battery pack 1. Referring to FIGS. 8 and 9, 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.

[0103] 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.

[0104] The power consumption device can be selected from a secondary battery, a battery module, or a battery pack depending on its usage needs.

[0105] 10 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.

[0106] 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.

[0107] 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.

[0108] 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 two 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 84 μm thick on one side. This was then slit to obtain a positive electrode plate 605 mm long and 88 mm wide, with a coating weight of 20 mg / cm. 2 and the compaction density is 2.4 g / cm 3 is.

[0109] (2) Manufacturing of negative electrode plates The negative electrode active material is artificial graphite, the conductive agent is acetylene black, and the thickener is sodium carboxymethyl cellulose (CMC). -Na ) and adhesive SBR were mixed in a mass ratio of 96.4:1:1.2:1.4, deionized water as a solvent was added, and the mixture was stirred using a vacuum mixer until the system became uniform, obtaining a negative electrode slurry. The negative electrode slurry was 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 one side. The negative electrode plate was 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 same lithium foil is attached to the non-reactive area and the terminal non-reactive area of ​​the negative electrode plate, and the theoretical capacity C of lithium in the lithium foil isLi and the capacitance C1 of the corresponding negative electrode film layer below is C Li = 100% C1 is satisfied, the distance between the side of the lithium foil closest to the reaction area and the reaction area is 3 mm, and a single-sided adhesive polyethylene film is attached as a barrier layer away from the reaction area to the lithium supply layer, the adhesive strength of the polyethylene film is 470 N / m, and the thickness is 20 μm.

[0110] (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.

[0111] (4) Separator manufacturing A polyethylene film with a thickness of 12 μm was selected as the separator.

[0112] (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 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.

[0113] Example 2 The secondary battery was manufactured in accordance with Example 1, except that in the manufacture of the negative electrode plate, a lithium-aluminum alloy was attached to the non-reactive area of ​​the negative electrode plate and the terminal non-reactive area, and the lithium discharge capacity was 1980 mAh / g.

[0114] Examples 3 to 6 The secondary battery was manufactured in the same manner as in Example 1, except that in the manufacture of the negative electrode plate, the distance between the side of the lithium foil closest to the reaction area and the reaction area was 0 mm, 2 mm, 5 mm, and 6 mm, respectively.

[0115] Examples 7 to 11 The secondary battery was manufactured in accordance with Example 1, except that in the manufacture of the negative electrode plate, lithium foil of the same specifications was attached to the non-reaction area and the terminal non-reaction area of ​​the negative electrode plate, and the theoretical capacity C of lithium in the lithium foil was Li and the capacitance C1 of the corresponding negative electrode film layer below are C Li =10%C1, C Li =20%C1, C Li =90%C1, C Li =120%C1 and C Li =130%C1 is satisfied.

[0116] Examples 12-13 The secondary battery was manufactured in the same manner as in Example 1, except that the thickness of the polyethylene film was 6 μm and 40 μm, respectively.

[0117] Examples 14-15 The secondary battery was manufactured in the same manner as in 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 polyethylene terephthalate film and a polyvinyl chloride film, respectively.

[0118] Example 16 The secondary battery was manufactured in the same manner as in Example 1, except that the non-reactive region of the negative electrode plate was coated with polytetrafluoroethylene as a barrier layer with a thickness of 20 μm.

[0119] Example 17 The secondary battery was manufactured in the same manner as in Example 1, except that the non-reactive region of the negative electrode plate was coated with polymethyl methacrylate as a barrier layer with a thickness of 20 μm.

[0120] Example 18 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 on the negative electrode plate on the side away from the reaction region of the lithium supplementary layer along the width direction of the negative electrode plate, the spacing region was formed by removing the negative electrode film layer by grinding, and its width was 15 mm and its depth was equal to the thickness of the negative electrode film layer, i.e., 61 μm, and a barrier layer was installed in the spacing region away from the reaction region.

[0121] Examples 19-20 The secondary battery was manufactured in the same manner as in Example 18, except that the width of the gap region was 5 mm and 50 mm, respectively.

[0122] Example 21 The secondary battery was fabricated in the same manner as in Example 18, 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.

[0123] 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.

[0124] Comparative Example 2 The secondary battery was manufactured in the same manner as in Example 1, except that in the manufacture of the negative electrode plate, a lithium supplementary layer was not provided in the non-reaction area, and a barrier layer was provided over the entire non-reaction area.

[0125] Comparative Example 3 The secondary battery was manufactured in the same manner as in Example 1, except that the lithium supplementary layer and the barrier layer were not provided in the non-reactive region in the manufacture of the negative electrode plate.

[0126] Secondary battery performance test The capacity measured after charging at 0.02C for 10 hours at 1.45°C is C0, and the capacity measured after charging to 3.65V at 0.33C at 25°C and then constant voltage down 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.

[0127] 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.

[0128] 3. Cycle performance of secondary batteries: At 45°C, the secondary battery was charged to 3.65 V at 1 C, then constant voltage was applied at 3.65 V to 0.05 C, and the battery was discharged to 2.5 V at 1 C. These steps were repeated until the capacity of the secondary battery was reduced to 80% of the initial capacity, and a full charge / discharge cycle test was performed, and the number of cycles was recorded.

[0129] 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.

[0130] [Table 1]

[0131] [Table 2]

[0132] [Table 3]

[0133] [Table 4]

[0134] [Table 5]

[0135] [Table 6]

[0136] As can be seen from Table 1, the number of cycles when the capacity retention rate of the secondary batteries of all the above examples is 80% is higher than that of the secondary batteries of the comparative examples.

[0137] Comparing Example 1 with Comparative Examples 1 to 3, it can be seen that the initial efficiency, storage performance, and cycle performance of the secondary battery can be clearly improved by providing a lithium supply layer and a barrier layer in the non-reactive region of the negative electrode plate.

[0138] Comprehensive comparison of Example 1 with Examples 3 to 6 reveals that when the distance between the side of the lithium supply layer closest to the reaction region and the reaction region is 2 mm to 5 mm, the initial efficiency of the secondary battery, the number of storage days when the capacity is 80%, and the number of cycles when the capacity retention rate is 80% can be further improved. When the distance between the side of the lithium supply layer closest to the reaction region and the reaction region is 0 mm, the initial efficiency of the secondary battery is good. However, if the side of the lithium supply layer closest to the reaction region is completely close to the edge of the reaction region, lithium deposition may occur in the reaction region, thereby affecting the safety of the battery core. Therefore, the side of the lithium supply layer closest to the reaction region should be greater than 0 mm.

[0139] When Example 1 and Examples 7 to 11 are compared comprehensively, the theoretical capacity C of lithium in the lithium supply layer Li and the capacity C1 of the negative electrode film layer corresponding to the lithium supplementary layer is 20% C1≦C Li If C≦120%C1 is satisfied, the initial efficiency, storage performance, and cycle performance of the secondary battery can be further improved. Li When C = 130%, the initial efficiency, storage performance, and cycle performance of the secondary battery are all good.Li If C1 is greater than 120%, localized lithium deposition in the negative electrode reaction area may occur. Li ≦120%C1 must be satisfied.

[0140] Comparing Example 1 with Examples 18 to 21 comprehensively, when a spacing region is installed on the negative electrode plate away from the reaction region of the lithium supply layer, the initial efficiency, storage performance, and cycle performance of the secondary battery can be further improved.

[0141] Comprehensively comparing Example 18 and Example 21, 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.

[0142] 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 and other methods that are constructed by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit of the present application. [Explanation of symbols]

[0143] 1 battery pack 2 Upper housing 3 Lower housing 4 battery modules 5 secondary battery 51 cases 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 disposed opposite to the positive electrode film layer and a non-reactive region not disposed opposite to the positive electrode film layer, wherein a lithium supplement layer and a barrier layer are disposed in the non-reactive region, A secondary battery, wherein the lithium replenishment layer is disposed at an end of the non-reaction region closer to the reaction region, and the barrier layer is disposed away from the lithium replenishment layer and away from the reaction region.

2. 2. The secondary battery according to claim 1, wherein the distance between the reaction region and the side of the lithium supply layer closest to the reaction region is 2 mm to 5 mm.

3. The secondary battery according to claim 1 , wherein the lithium supplementary layer contains a material capable of providing active lithium.

4. The theoretical capacity C of lithium in the lithium replenishment layer Ｌｉ is 20% C １ ≦C Ｌｉ ≦120%C １ where C １ is the capacity of the negative electrode film layer corresponding to the lithium supplementary layer.

5. 2. The secondary battery according to claim 1, wherein the barrier layer is selected from a film or a coating that cannot be wetted by an electrolyte, the film comprising one or more of polypropylene, polyethylene, polyester fiber, and polyvinyl chloride, 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.

6. 2. The secondary battery according to claim 1, wherein the barrier layer has a thickness of 6 μm to 40 μm.

7. The secondary battery according to claim 5 , wherein the film has adhesive properties and an adhesive force greater than 20 N / m.

8. 2. The secondary battery of claim 1, wherein a spacing region is provided on the negative electrode plate on a side of the lithium replenishment layer away from the reaction region, along the width direction of the negative electrode plate, and the barrier layer is provided away from the spacing region and away from the reaction region.

9. 9. The secondary battery according to claim 8, wherein the width of the gap region is 5 mm to 50 mm.

10. The secondary battery according to claim 8 , wherein the depth of the gap region is equal to the thickness of the negative electrode film layer.

11. 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; and (5) manufacturing a secondary battery; wherein step (2) includes providing a lithium supplementary layer and 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 reaction region disposed opposite to the positive electrode film layer and a non-reaction region not disposed opposite to the positive electrode film layer, and a lithium supplement layer and a barrier layer are disposed in the non-reaction region, The method, wherein the lithium replenishment layer is disposed at an end of the non-reaction region closer to the reaction region, and the barrier layer is disposed away from the lithium replenishment layer and away from the reaction region.

12. The method of claim 11 , wherein the barrier layer is applied by a coating or pasting process.

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

14. A battery pack comprising the battery module according to claim 13.

15. 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 10, the battery module according to claim 13, and the battery pack according to claim 14.

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