Negative electrode plate, its manufacturing method, secondary battery, and power consumption device

Abstract

The present application provides a negative electrode plate, a manufacturing method thereof, a secondary battery, and a power consumption device. The method includes: providing a negative electrode current collector; applying a photosensitive paste on at least one surface of the negative electrode current collector and curing the paste to form a photosensitive layer; patterning light into a predetermined pattern, and irradiating the light from a surface of the photosensitive layer away from the negative electrode current collector to expose the photosensitive layer; developing the exposed photosensitive layer to obtain a photosensitive layer having recesses; filling the recesses with a negative electrode slurry, curing the negative electrode slurry to form a negative electrode film layer; and removing at least a part of the photosensitive layer to obtain a negative electrode plate. The present application exposes and develops the photosensitive paste to precisely control the structure and distribution of the recesses in the photosensitive paste, and cooperates with the photosensitive paste to assist in the formation of holes in the negative electrode film layer, thereby precisely controlling the pore structure in the negative electrode film layer, which is advantageous for improving the fast charging performance and safety performance of the secondary battery.

Description

[Technical field]

[0001] The present application relates to the field of batteries, and in particular to a negative electrode plate, a method for manufacturing the same, a secondary battery, and a power consuming device. [Background technology]

[0002] 2. Description of the Related Art Secondary batteries have characteristics such as high capacity and long service life, and are therefore widely used in electronic devices, such as mobile phones, notebook computers, battery cars, electric cars, electric airplanes, electric steamships, electric toy cars, electric toy steamships, electric toy airplanes, and electric tools.

[0003] As the application range of batteries becomes wider, the requirements for the performance of secondary batteries are becoming increasingly stringent. In order to improve the performance of secondary batteries, the electrodes in the secondary batteries, such as the negative electrodes, are generally optimized and improved. However, when the negative electrodes are currently applied to secondary batteries, their fast charging ability and safety performance are still poor, and further improvements are required. Summary of the Invention

[0004] The present application has been made in view of the above-mentioned problems, and has an object to provide a negative electrode plate, a manufacturing method thereof, a secondary battery, and a power consuming device.

[0005] A first aspect of the present application provides a method for manufacturing a negative electrode plate, the method including: providing a negative electrode current collector; applying a photosensitive paste on at least one surface of the negative electrode current collector and curing the paste to form a photosensitive layer; patterning light into a predetermined pattern and directing the light to the photosensitive layer from a surface of the photosensitive layer remote from the negative electrode current collector to expose the photosensitive layer; developing the exposed photosensitive layer to obtain a photosensitive layer having recesses; filling the recesses with a negative electrode slurry and curing the negative electrode slurry to form a negative electrode film layer; and removing at least a portion of the photosensitive layer to obtain a negative electrode plate.

[0006] Therefore, the present application can precisely control the structure and distribution of the recesses in the photosensitive paste by exposing and developing the photosensitive paste, and can precisely control the pore structure in the negative electrode film layer by assisting the formation of holes in the negative electrode film layer in cooperation with the photosensitive paste, which is favorable for the negative electrode film layer to absorb the electrolyte with the assistance of the pore structure, and to improve the transport speed of the active ions in the liquid phase and the speed at which the active ions are desolvated and enter the negative electrode active material in the negative electrode film layer, thereby improving the dynamic performance of the negative electrode plate, and when the negative electrode plate is applied to a secondary battery, the fast charging performance of the secondary battery can be improved. The improved dynamic performance of the negative electrode plate can reduce the problem of concentration polarization, and the active ions are less likely to precipitate locally and form dendrites, thereby improving the safety performance of the secondary battery.

[0007] In any embodiment, the step of removing at least a portion of the photosensitive layer includes a time for removing the photosensitive layer of 10 s to 60 s, and the removal degree of the photosensitive paste may be adjusted by controlling the processing time.

[0008] In any embodiment, after the step of developing the photosensitive layer, the method further includes heat-treating the developed photosensitive layer, and optionally, the temperature of the heat treatment is 200° C. to 250° C., and / or the time of the heat treatment is 10 min to 20 min. By further heat-treating the developed photosensitive layer, further cross-linking occurs inside the photosensitive layer, which can improve the adhesive performance of the photosensitive layer, thereby improving the bond strength between the photosensitive layer and the negative electrode current collector 5211.

[0009] In any embodiment, in the step of applying a photosensitive paste onto at least one surface of the negative electrode current collector and curing the paste to form a photosensitive layer, at least one of the following conditions is satisfied: (1) the application speed is 20 m / min to 70 m / min; (2) the curing temperature is 60° C. to 90° C.; (3) the curing time is 60 s to 90 s; and (4) the photosensitive layer contains a positive-type photosensitive paste or a negative-type photosensitive paste.

[0010] In any embodiment, the thickness of the photosensitive layer is T1 μm, the thickness of the negative electrode film layer is T2 μm, and 1.0≦T1 / T2≦1.5. The thickness of the photosensitive layer should be close to the thickness of the negative electrode film layer, and such an arrangement is favorable for transferring the preset pattern to the negative electrode film layer and assists the formation of holes in the negative electrode film layer. Since the photosensitive paste is a flowable liquid, it generally needs to be heat-treated to harden it, and the forming state of the photosensitive paste can be controlled by adjusting the conditions of the heat treatment.

[0011] In any embodiment, the step of patterning light into a preset pattern and exposing the photosensitive layer by making the light incident on the photosensitive layer from a surface of the photosensitive layer remote from the negative electrode current collector includes employing a mask plate to expose the photosensitive layer by making the light incident on the photosensitive layer from a surface of the photosensitive layer remote from the negative electrode current collector, and optionally the method further includes satisfying at least one of the following conditions: (I) the exposure time is 1s to 10s; (II) the mask plate includes a plurality of holes, and the diameter of the holes is 10μm to 2500μm; and (III) the distance between the mask plate and the photosensitive layer is 0 to 400μm, and optionally 0 to 200μm. The exposure time can adjust the cross-linking degree and development effect of the exposed area, and the result of subsequent hole formation can be adjusted by adjusting the exposure time. By adjusting the distance between the mask plate and the photosensitive layer, the pattern on the mask plate can be proportionally scaled and transferred to the photosensitive layer.

[0012] In an optional embodiment, the anode slurry includes an anode active material, the anode active material including one or more of artificial graphite, natural graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate.

[0013] A second aspect of the present application provides a negative electrode plate, the negative electrode plate including 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 first hole, wherein a size of the first hole along a thickness direction of the negative electrode plate is H1 μm, and a size of the negative electrode film layer along a thickness direction of the negative electrode plate is H μm, optionally, 0.2≦H1 / H≦1.0, further optionally, 0.5≦H1 / H≦1.0.

[0014] Thus, the present application provides a first hole in the negative electrode membrane layer, and absorbs the electrolyte into the negative electrode membrane layer through the first hole, thereby improving the transport speed of active ions in the liquid phase and the speed at which the active ions are desolvated and enter the negative electrode active material. This further improves the dynamic performance of the negative electrode plate, and improves the fast charging performance and safety performance of the secondary battery using the negative electrode plate. When the above range is met, the present application can ensure the occupied space of the negative electrode active material under the condition of improving the liquid absorption ability, thereby ensuring the gram capacity of the negative electrode plate.

[0015] In any embodiment, the negative plate satisfies at least one of the following conditions: (a) 10≦D≦500, where D μm is the pore size of the first hole, and optionally 10≦D≦100, (b) 10≦H1≦300, and (c) 50≦H≦300. Thus, the present application can further improve the dynamic performance of the negative plate when at least one of the above conditions is satisfied.

[0016] In any embodiment, the first holes are provided in a plurality, and the plurality of first holes are provided at intervals, with a distance between two adjacent first holes being W μm, where 100≦W≦1000, and optionally 100≦W≦200. When the distance between two adjacent holes is within the above range, the porosity of the entire negative electrode membrane layer can be guaranteed, and in addition to improving the dynamic performance of the negative electrode plate, the gram capacity of the negative electrode plate can be guaranteed.

[0017] A third aspect of the present application provides a secondary battery, the secondary battery including the negative electrode plate according to any one of the embodiments in the second aspect of the present application.

[0018] A fourth aspect of the present application provides a power consuming device including the secondary battery according to any one of the embodiments in the third aspect of the present application. [Brief description of the drawings]

[0019] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings that need to be used in the embodiments of the present application. It is obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can also obtain other drawings based on the drawings without exerting creative efforts. [Figure 1] FIG. 1 is a schematic diagram of an embodiment of a negative electrode plate manufacturing method according to the present application. [Diagram 2] FIG. 2 is a schematic diagram of an embodiment of a negative electrode plate manufacturing method according to the present application. [Diagram 3] FIG. 3 is a schematic diagram of an embodiment of a negative electrode plate manufacturing method according to the present application. [Figure 4] FIG. 4 is a schematic diagram of an embodiment of a negative electrode plate manufacturing method according to the present application. [Diagram 5] FIG. 5 is a fifth schematic diagram of an embodiment of a negative plate manufacturing method according to the present application. [Figure 6] FIG. 6 is a schematic diagram of an embodiment of a negative plate manufacturing method according to the present application. [Figure 7] FIG. 7 is a schematic diagram of an embodiment of a negative plate manufacturing method according to the present application. [Figure 8] FIG. 2 is a structural schematic diagram of an electrode assembly of a secondary battery of the present application. [Figure 9] FIG. 1 is a schematic diagram of one embodiment of a secondary battery of the present application. [Figure 10] FIG. 10 is an exploded schematic view of an embodiment of the secondary battery of FIG. [Figure 11] FIG. 1 is a schematic diagram of one embodiment of a battery module of the present application. [Figure 12] FIG. 1 is a schematic diagram of one embodiment of a battery pack of the present application. [Figure 13] FIG. 13 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 12. [Figure 14] 1 is a schematic diagram of an embodiment of a power consuming device in which the secondary battery of the present application is used as a power source.

[0020] The drawings are not necessarily drawn to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments specifically disclosing the negative electrode plate and its manufacturing method, secondary battery, 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 duplicated description of structures that are actually the same may be omitted. This is to avoid the following description becoming unnecessarily long and to allow those skilled in the art to easily understand. Note that the drawings and the following description are provided to allow those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0022] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the extreme values, and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a 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 envisaged. However, if 1 and 2 are listed as minimum range values, and 3, 4, and 5 are listed as maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all envisaged. In this application, unless otherwise specified, the numerical range "ab" represents a shorthand representation of 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 a list of all real numbers between "0-5" already listed in this specification, and "0-5" is just a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] Unless otherwise stated, all the embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.Unless otherwise stated, all the technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0024] Unless otherwise stated, all steps in this application may be performed in sequence or randomly, and preferably in sequence. For example, a method including steps (a) and (b) means that the method may include steps (a) and (b) performed in sequence, or may include steps (b) and (a) performed in sequence. For example, when it is mentioned that the method may further include step (c), it means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), etc.

[0025] Unless otherwise stated, the terms "comprise" and "comprises" referred to in this application may be open ended or closed ended. For example, "comprise" and "comprises" may further include or include other ingredients not listed, or may include or include only the listed ingredients.

[0026] 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 in the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); and A and B are both true (or exist).

[0027] As used in this application, the terms "plurality" and "multiple types" mean two or more than two.

[0028] In the process of charging a secondary battery, the negative plate generally requires the following electrochemical processes: (1) the active ions (such as lithium ions, sodium ions, etc.) desorbed from the positive active material enter the electrolyte and follow the electrolyte into the pores of the negative membrane layer to complete liquid-phase conduction in the pores of the active ions, which includes liquid-phase diffusion; (2) the active ions and electrons complete charge exchange on the surface of the negative active material; (3) the active ions are desolvated and undergo solid-phase conduction from the surface of the negative active material to the inside of the crystal of the negative active material.

[0029] In a rapid charging system, the liquid phase transport rate and desolvation rate of active ions are low. In order to improve the above problem and increase the amount of liquid absorbed by the negative electrode membrane layer, through-holes are generally provided in the negative electrode membrane layer, and the electrolyte enters the negative electrode membrane layer through the through-holes, which is favorable for the liquid phase transport of active ions.

[0030] However, the inventors have found that: when forming holes in the related art, a hole-forming agent is generally used, and when it volatilizes, it exerts an etching effect to etch holes in the negative electrode film layer, but the diameter of the hole path produced by such a hole-forming method cannot be controlled, which may result in non-uniformity in the performance of the entire layer of the negative electrode film layer; active ions, such as lithium ions, may still have concentration polarization problems locally in the negative electrode film layer; lithium ions are prone to lithium deposition on the surface of the negative electrode film layer away from the negative electrode current collector, and the deposited metallic lithium may further increase the potential barrier for lithium ions to enter the negative electrode active material, which may further exacerbate the concentration polarization problem; lithium ions may further deposit on the surface of the negative electrode film layer and further form lithium dendrites, which may break through the separator and cause a short circuit between the positive and negative plates, which may pose a safety risk; and the liquid phase conduction rate of active ions is low, which reduces the fast charging ability of the secondary battery.

[0031] In view of this, the inventor provides a method for manufacturing a negative plate, which employs photo-etching technology to transfer a preset pattern to the negative plate, assisting in forming holes in the negative plate and allowing the distribution of holes to be precisely controlled, thereby improving the safety performance and fast charging performance when the negative plate is applied to a secondary battery.

[0032] Manufacturing method of negative electrode plate

[0033] According to a first aspect, the present application provides a method for manufacturing a negative electrode plate, the method comprising:

[0034] Step S100, providing a negative electrode current collector;

[0035] Step S200: applying a photosensitive paste onto at least one surface of a negative electrode current collector and curing the paste to form a photosensitive layer;

[0036] Step S300: patterning light into a preset pattern, and exposing the photosensitive layer to the light by directing the light to the photosensitive layer from a surface of the photosensitive layer away from the negative electrode current collector;

[0037] Step S400: developing the exposed photosensitive layer to obtain a photosensitive layer having a recess;

[0038] Step S500: filling the recess with a negative electrode slurry and hardening the negative electrode slurry to form a negative electrode film layer;

[0039] Step S600 includes removing at least a portion of the photosensitive layer to obtain a negative plate.

[0040] According to the method of the embodiment of the present application, the photosensitive paste is exposed and developed, so that the structure and distribution of the recesses in the photosensitive paste can be precisely controlled; the photosensitive paste is used to assist the formation of holes in the negative electrode film layer, so that the pore structure in the negative electrode film layer can be precisely controlled; the pore structure of the negative electrode film layer can be improved by the pore structure, and the active ions can be absorbed by the negative electrode film layer to improve the transport speed in the liquid phase and the speed of desolvation into the negative active material of the negative electrode film layer, thereby improving the dynamic performance of the negative electrode plate; when the negative electrode plate is used in a secondary battery, the fast charging performance of the secondary battery can be improved; and the improved dynamic performance of the negative electrode plate can reduce the problem of concentration polarization, and the active ions are less likely to precipitate locally to form dendrites, so that the safety performance of the secondary battery can be improved.

[0041] As shown in FIG. 1, in some embodiments, the negative electrode current collector 5211 in step S100 may adopt a metal foil sheet or a composite current collector. For example, a copper foil may be adopted as the metal foil sheet. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0042] Step S200 is a process for forming the photosensitive layer 5214. In some embodiments, the negative electrode current collector 5211 in step S200 includes two surfaces facing each other along its thickness direction, and the photosensitive layer 5214 may be provided on one of the two surfaces, or on both surfaces. As shown in FIG. 1, the photosensitive layer 5214 is applied on one surface of the negative electrode current collector 5211.

[0043] The photosensitive layer 5214 is a film layer structure composed of a photosensitive paste of a polymeric compound sensitive to light, and when this type of polymeric compound is irradiated with an external radiation source (e.g., ultraviolet light having a certain radiation amount), a photochemical reaction occurs immediately, and the cross-linking of the molecules occurs and the polymeric compound is hardened, and the molecules can change from the original linear structure to a three-dimensional cross-linked network structure. According to the wavelength of the exposure light source, the photosensitive paste includes one or more of G-line photosensitive paste, I-line photosensitive paste, KrF photosensitive paste, and ArF photosensitive paste. According to the difference in the dissolving position during the development process, the photosensitive paste may be divided into a positive photosensitive paste and a negative photosensitive paste, and the exposed part of the positive photosensitive paste is dissolved during development, while the exposed part of the negative photosensitive paste is not dissolved during development, and the unexposed part is dissolved.

[0044] Optionally, the photosensitive paste may be composed of a photosensitive resin as a base, a monomer crosslinking agent, a photosensitizer, a polymerization inhibitor, etc., and the photosensitive paste has excellent light transmittance and can be rapidly cured under irradiation of a light source to be adhered to the negative electrode current collector 5211. Exemplarily, the photosensitive paste may include a photopolymerization type, a photocrosslinking type, a photodecomposition type, etc. photosensitive paste. The photopolymerization type photosensitive paste may be considered as a positive type photosensitive paste, which contains an olefin monomer and can absorb light energy during exposure to generate free radicals, and then crosslinking polymerization of the free radicals occurs, and finally generates a polymer. The photodecomposition type photosensitive paste may also be considered as a positive type photosensitive paste, which can undergo a photochemical reaction after absorbing light energy, which significantly changes the affinity and solubility of the material, and causes dissolution of the photosensitive resin during development. The photo-crosslinkable photosensitive paste may be considered as a negative photosensitive paste, which includes polyvinyl laurate, in which the double bonds in the molecule are broken during exposure, and cross-linking reaction occurs between the chains, forming a stable network structure, so that the exposed part is insoluble in the developer. The specific material types of each of the above types of photosensitive paste may be selected from the common materials in the prior art, and will not be further described here.

[0045] In some embodiments, when the photosensitive paste is applied onto the negative electrode current collector 5211, the application speed is 20 m / min to 70 m / min, and the application amount of the photosensitive paste can be adjusted by controlling the application speed of the photosensitive paste, thereby adjusting the thickness of the photosensitive layer 5214 formed from the photosensitive paste. Exemplarily, the application speed may be 20 m / min, 25 m / min, 30 m / min, 35 m / min, 40 m / min, 45 m / min, 50 m / min, 60 m / min, 70 m / min, or a range consisting of any two of the above numerical values.

[0046] Since the photosensitive paste is a flowable liquid, it is generally necessary to heat treat it in order to harden it, for example, the photosensitive paste is baked in an oven, and optionally, the hardening temperature is 60°C to 90°C, and / or the hardening time is 60s to 90s. Exemplarily, the hardening temperature may be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or a range consisting of any two of the above values. The hardening time may be 60s, 65s, 70s, 75s, 80s, 85s, 90s, or a range consisting of any two of the above values. The hardening temperature and time may be arbitrarily combined, for example, the hardening temperature may be 60°C, and the hardening time may be 90s.

[0047] Optionally, the photosensitive layer 5214 has a thickness T1 μm, the negative electrode film layer 5212 has a thickness T2 μm, and 1.0≦T1 / T2≦1.5.

[0048] The thickness of the photosensitive layer 5214 should be close to that of the negative electrode film layer 5212, which is advantageous for transferring a preset pattern to the negative electrode film layer 5212 and assists in forming holes in the negative electrode film layer 5212. Exemplarily, T1 / T2 may be 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, or a range consisting of any two of the above values.

[0049] Step S300 is a process of exposing the photosensitive layer 5214, and the preset pattern is the light incidence area controlled according to the distribution form of the holes that need to be set in the negative electrode film layer 5212. Considering that the photosensitive paste includes positive photosensitive paste and negative photosensitive paste, when the positive photosensitive paste is adopted, the preset pattern can be the same as the exposure area, and when the negative photosensitive paste is adopted, the preset pattern can be the same as the non-exposure area. Figure 2 shows the exposure process, and the arrow in Figure 2 indicates the light incidence direction.

[0050] This is because the exposure distinguishes between exposed and unexposed areas in the photosensitive paste, which is useful for subsequent development. The exposure time not only determines the degree of cross-linking in the exposed area and the development effect, but also affects the clarity of the pattern formed in the photosensitive paste. This is because if the exposure time is too long, excessive cross-linking of the photosensitive paste in the exposed area may occur, causing cross-linking of the photosensitive paste at the boundary between the exposed and unexposed areas, and if the exposure time is too short, the degree of cross-linking of the photosensitive paste in the exposed area may be insufficient. Optionally, the exposure time may be 1s to 10s. Exemplarily, the exposure time may be 1s, 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, or a range consisting of any two of the above values.

[0051] In some embodiments, there are multiple types of exposure light sources, such as full spectrum ultraviolet (300 nm to 450 nm), G-line (436 nm), I-line (365 nm), deep ultraviolet (DUV, including 248 nm and 193 nm), and extreme ultraviolet (EUV). Based on the type of photosensitive paste, a light source for the corresponding photosensitive paste is selected. For example, if the photosensitive paste is a G-line photosensitive paste, a G-line light source is selected accordingly as the exposure light source. Also, for example, if the photosensitive paste is a KrF photosensitive paste, a deep ultraviolet light source is selected accordingly as the exposure light source. The integrated light amount is 40 mj / cm. 2 ~75mj / cm 2 For example, the integrated light amount may be 40 mj / cm2 , 45 mJ / cm 2 , 50 mJ / cm 2 , 55 mJ / cm 2 , 60 mJ / cm 2 , 65 mJ / cm 2 , 70 mJ / cm 2 , 75 mJ / cm 2 Alternatively, the range may be any two of the above values. The exposure time and the integrated amount of light of the exposure can be coordinated to control the clarity of the pattern formed in the photosensitive paste.

[0052] To facilitate the exposure process, a mask plate 5215 is generally used in combination with the mask plate 5215, for example a metal template having through holes, the diameter of which may be 10 μm-2500 μm, and the distance between the mask plate 5215 and the photosensitive layer 5214 may be 0-400 μm, optionally 0-200 μm. By adjusting the distance between the mask plate 5215 and the photosensitive layer 5214, the pattern on the mask plate 5215 can be proportionally scaled and enlarged before being transferred to the photosensitive layer 5214.

[0053] The setting of the mask plate 5215 is related to a preset pattern, and selects an appropriate mask plate 5215 based on the required preset pattern. Optionally, the type of holes in the mask plate 5215 has multiple forms, such as regular polygon holes, irregular polygon holes, circular holes, elliptical holes, etc., specifically, the holes may be diamond holes, rectangular holes, triangular holes, or elliptical holes, etc.

[0054] Step S400 is a developing process, in which the photosensitive layer 5214 after exposure reacts with the developer to obtain the photosensitive layer 5214 having the recess 52141. Specifically, the exposed area of ​​the positive photosensitive paste can react with the developer, dissolve and be washed away, and the non-exposed area of ​​the negative photosensitive paste can react with the developer, dissolve and be washed away, thereby leaving the corresponding groove or through hole in the photosensitive layer 5214. Exemplarily, the developer may include tetramethylammonium hydroxide, n-butyl acetate or 0.4% KOH solution. FIG. 3 shows the developing process using the positive photosensitive paste, and FIG. 4 shows the developing process using the negative photosensitive paste.

[0055] The method may further include S700 after step S400, in which the developed photosensitive layer 5214 is heat-treated. By further heat-treating the developed photosensitive layer 5214, further cross-linking occurs inside the photosensitive layer 5214, and the adhesive performance of the photosensitive layer 5214 can be improved, thereby improving the bonding strength between the photosensitive layer 5214 and the negative electrode current collector 5211. Optionally, the temperature of the heat treatment is 200°C to 250°C, and / or the time of the heat treatment is 10 min to 20 min. Exemplarily, the temperature of the heat treatment may be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, or a range consisting of any two of the above values. The heat treatment time may be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, or a range consisting of any two of the above values. The heat treatment temperature and time may be arbitrarily combined, for example, the heat treatment temperature may be 200° C. and the heat treatment time may be 20 min.

[0056] Step S500 is the manufacturing process of the negative electrode film layer 5212. The photosensitive layer 5214 is coated with the negative electrode slurry, and the negative electrode film layer 5212 is formed through a curing process such as drying and cold pressing, and the negative electrode slurry is filled into the recess 52141, and the negative electrode slurry is dried to form the negative electrode film layer 5212. FIG. 5 shows the manufacturing process of the negative electrode film layer 5212, which is only a schematic of the manufacturing process, and the thickness ratio between layers does not represent the structure of the negative electrode plate 521.

[0057] Step S600 is a glue removal process, which removes the photosensitive paste that has not reacted with the developer to expose the negative electrode current collector 5211. Of course, the photosensitive paste may not be completely removed, and some of the photosensitive paste may remain on the surface of the negative electrode current collector 5211, which corresponds to removing a portion of the photosensitive layer 5214 along the thickness direction of the negative electrode plate 521. In some embodiments, the removal of the photosensitive paste may be performed by wet glue removal or dry glue removal, for example, by using a remover such as O2 / N2 plasma, Cl2 / HBr, hydroxylamine compound, or HF / HNO3 solution buffered with H2O to react with the photosensitive layer 5214 in the negative electrode plate 521 and dissolve or incinerate the photosensitive paste without reacting with the negative electrode active material. Through the above process, the photosensitive layer 5214 may be completely removed, or the photosensitive layer 5214 may be partially removed and the other part may be retained. Optionally, the processing time may be 10s-60s, and the degree of removal of the photosensitive paste may be adjusted by controlling the processing time. The degree of removal of the photosensitive paste may be adjusted by controlling the concentration of the remover. FIG. 6 shows a process of glue removal, in which the glue is not completely removed, but some photosensitive layer 5214 is retained, and the first hole 5213 is a blind hole. FIG. 7 shows another process of glue removal, in which the glue is completely removed, and the first hole 5213 is a straight through hole.

[0058] In this application, a straight through hole refers to a through hole that penetrates the negative electrode film layer 5212 along the thickness direction of the negative electrode plate 521, where almost no photosensitive layer 5214 remains on the negative electrode plate 521, and a blind hole refers to a hole structure that does not penetrate the negative electrode film layer 5212.

[0059] The presence of the first holes 5213 in the negative electrode membrane layer 5212 is advantageous in that the electrolyte can be absorbed into the negative electrode membrane layer 5212 through the first holes 5213, thereby improving the amount of liquid absorbed by the negative electrode plate 521 and accelerating the liquid phase transport speed of the active ions, so that the active ions can be more quickly desolvated and introduced into the negative electrode active material of the negative electrode membrane layer 5212, thereby improving the transport speed of the active ions in the system, improving the dynamic performance of the negative electrode plate 521, reducing the risk of concentration polarization occurrence, improving the safety performance of the secondary battery using the negative electrode plate 521, and improving the rapid charging performance of the secondary battery.

[0060] In some embodiments, the negative electrode slurry includes a negative electrode active material, and the negative electrode active material may be a negative electrode active material for batteries well known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a 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 silicon 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. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for a battery may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0061] In some embodiments, the negative electrode slurry optionally further comprises a negative electrode 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).

[0062] In some embodiments, the anode slurry 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.

[0063] In some embodiments, the negative electrode slurry optionally further comprises other auxiliary agents, such as a thickening agent (eg, sodium carboxymethylcellulose (CMC-Na)).

[0064] Negative plate 521

[0065] The second aspect of the present application further provides a negative plate 521, which may be manufactured by the method of any one of the embodiments in the first aspect of the present application.

[0066] In some embodiments, the negative electrode plate 521 includes a negative electrode current collector 5211 and a negative electrode membrane layer 5212 disposed on at least one surface of the negative electrode current collector 5211, the negative electrode membrane layer 5212 includes a first hole 5213, the size of the first hole 5213 along the thickness direction of the negative electrode plate 521 is H1 μm, and the size of the negative electrode membrane layer 5212 along the thickness direction of the negative electrode plate 521 is H μm, where 0.2≦H1 / H≦1.0, and optionally 0.5≦H1 / H≦1.0.

[0067] H1 / H=1 indicates that the first hole 5213 is a straight through hole penetrating the negative electrode film layer 5212. H1 / H<1 indicates that the first hole 5213 does not completely penetrate the negative electrode film layer 5212. In this case, it may be considered that the photosensitive layer 5214 remains between the first hole 5213 and the negative electrode current collector 5211, and the photosensitive layer 5214 is located in the negative electrode film layer 5212 and is disposed on the surface of the negative electrode current collector 5211. Exemplarily, H1 / H may be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a range consisting of any two of the above values.

[0068] In the present application, the first hole 5213 is provided in the negative electrode membrane layer 5212, and the electrolyte is absorbed into the negative electrode membrane layer 5212 through the first hole 5213, thereby improving the transport speed of the active ions in the liquid phase and the speed at which the active ions are desolvated and introduced into the negative electrode active material. This can further improve the dynamic performance of the negative electrode plate 521, and improve the fast charging performance and safety performance of the secondary battery using the negative electrode plate 521. When the above range is satisfied, the present application can ensure the occupied space of the negative electrode active material under the condition of improving the liquid absorption ability, thereby ensuring the gram capacity of the negative electrode plate 521.

[0069] Through research, the inventors have found that the pore size and distribution pattern of the first pores 5213 and the negative electrode membrane layer 5212 have certain effects on the liquid phase transport of active ions, and the dynamic performance of the negative electrode plate 521 can be further improved when at least one of the following conditions is met:

[0070] In some embodiments, 50≦H≦300. Exemplarily, the size of the negative electrode film layer 5212 along the thickness direction, i.e., the size of the depth of the first hole 5213, may be 50 μm, 60 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 250 μm, 300 μm, or a range consisting of any two of the above numerical values.

[0071] When the size of the negative electrode film layer 5212 along the thickness direction is within the above range, the gram capacity of the negative electrode plate 521 can be guaranteed.

[0072] In some embodiments, 10≦H1≦300. Exemplarily, the size of the first hole 5213 along the thickness direction, i.e., the size of the depth of the first hole 5213, may be 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 250 μm, 300 μm, or a range consisting of any two of the above values. In the present application, the depth of the first hole 5213 is equal to or less than the thickness of the negative electrode film layer 5212.

[0073] If the hole depth of the first hole 5213 is too small, it is disadvantageous for absorbing the electrolyte, and if the hole depth is too large, the active ions may be directly deposited on the negative electrode current collector 5211. Therefore, when the hole depth of the first hole 5213 is within an appropriate range, it is advantageous for absorbing the electrolyte and improving the dynamic performance of the negative electrode plate 521.

[0074] In some embodiments, the diameter of the first holes 5213 is D μm, where 10≦D≦500, and optionally, 10≦D≦100. Exemplarily, the diameter of the first holes 5213 may be 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 300 μm, 400 μm, 500 μm, or a range consisting of any two of the above numerical values.

[0075] If the pore size of the first hole 5213 is too small, it is disadvantageous for liquid absorption, and if the pore size is too large, the space occupied by the negative electrode active material becomes too small, which is disadvantageous for ensuring the gram capacity of the negative electrode plate 521. When the pore size is within an appropriate range, it is advantageous for absorbing the electrolyte and improving the dynamic performance of the negative electrode plate 521, and the gram capacity of the negative electrode plate 521 can be guaranteed.

[0076] In some embodiments, the first holes 5213 are provided in a plurality, and the plurality of first holes 5213 are provided at intervals, with the interval between two adjacent first holes being W μm, where 100≦W≦1000, and optionally 100≦W≦200. Exemplarily, three adjacent holes may form an equilateral triangle, and the interval between two adjacent holes may be adjusted to W μm≧100 μm. Exemplarily, the interval between two adjacent holes may be 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 400 μm, 450 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, or a range consisting of any two of the above values.

[0077] When the spacing between two adjacent holes is within the above range, the porosity of the entire negative electrode membrane layer 5212 can be guaranteed, and in addition to improving the dynamic performance of the negative electrode plate 521, the gram capacity of the negative electrode plate 521 can be guaranteed.

[0078] secondary battery

[0079] According to a third aspect, the present application provides a secondary battery, the secondary battery 5 including a negative electrode plate 521 according to any one of the embodiments of the second aspect of the present application, which can improve the fast charging performance and safety performance of the secondary battery.

[0080] [Positive plate]

[0081] The secondary battery 5 further includes a positive electrode plate 522 .

[0082] In some embodiments, the positive plate 522 includes a positive current collector and a positive film layer disposed on at least one surface of the positive current collector. For example, the positive current collector has two surfaces facing each other in the thickness direction of the positive current collector, and the positive film layer is disposed on either or both of the two facing surfaces of the positive current collector.

[0083] The positive electrode film layer includes a positive electrode active material, which may be a positive electrode active material for secondary batteries well known in the art. For example, the positive electrode active material may include at least one of a layered structure positive electrode active material (such as ternary, lithium / sodium nickelate, lithium / sodium cobaltate, lithium / sodium manganate, lithium / sodium rich layered and rock salt phase layered materials), an olivine type phosphate active material, and a spinel structure positive electrode active material (such as spinel lithium manganate, spinel lithium nickel manganate, lithium rich spinel lithium manganate and lithium nickel manganate).

[0084] For example, the general formula of the layered positive electrode active material is Li x A y Ni a Co b Mn c M (1-a-b-c) Y z Wherein, 0≦x≦2.1, 0≦y≦2.1, and 0.9≦x+y≦2.1, 0≦a≦1, 0≦b≦1, 0≦c≦1, and 0.1≦a+b+c≦1, and 1.8≦z≦3.5, A is selected from one or more of Na, K, and Mg, M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce, and Y is selected from one or more of O and F. Optionally, y=0. Specifically, the layered structure positive electrode active material is lithium cobalt oxide LCO, lithium nickel oxide LNO, lithium manganese oxide LMO, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811) and LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523) may be included.

[0085] For example, the general formula of the olivine-type phosphate active material is Li x A y Me a M b P 1-c X c Y z wherein 0≦x≦1.3, 0≦y≦1.3, and 0.9≦x+y≦1.3; 0.9≦a≦1.5, 0≦b≦0.5, and 0.9≦a+b≦1.5; 0≦c≦0.5; and 3≦z≦5; A is selected from one or more of Na, K, and Mg; Me is selected from one or more of Mn, Fe, Co, and Ni; M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X is selected from one or more of S, Si, Cl, B, C, and N; and Y is selected from one or more of O and F. Specifically, the olivine-type phosphate active material includes one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0086] For example, the general formula of the positive electrode active material having a spinel structure is Li x A y Mn a M 2-a Y z where 0≦x≦2, 0≦y≦1, and 0.9≦x+y≦2, 0.5≦a≦2, and 3≦z≦5; A is selected from one or more of Na, K, and Mg; M is selected from one or more of Ni, Co, B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y is selected from one or more of O and F. Specifically, the positive electrode active material having a spinel structure is LiMn2O4, LiNi 0.5 Mn 1.5 O4, LiCr 0.3 Mn 1.7 O4, Li 1.1 Al 0.1 Mn 1.9O4, Li2Mn2O4 and Li 1.5 Contains one or more of Mn2O4.

[0087] In some embodiments, the positive electrode membrane layer optionally further includes a positive electrode conductive agent. The present application is not particularly limited to the type of the positive electrode conductive agent, and for example, the positive electrode conductive agent includes one or more combinations selected from superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, based on the total mass of the positive electrode membrane layer, the mass percentage of the positive electrode conductive agent is 5% or less.

[0088] In some embodiments, the positive electrode membrane layer optionally further includes a positive electrode adhesive. The present application is not particularly limited to the type of the positive electrode adhesive, and as an example, the positive electrode adhesive may include one or more combinations selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. In some embodiments, based on the total mass of the positive electrode membrane layer, the mass percentage of the positive electrode adhesive is 5% or less.

[0089] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. An example of the metal foil sheet may be an aluminum foil or an aluminum alloy foil. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric material base layer. For example, the metal material may include one or more combinations selected from aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, and the polymeric material base layer may include one or more combinations selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).

[0090] The positive electrode membrane layer is generally formed by applying a positive electrode slurry onto a positive electrode current collector, drying, and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, an optional conductive agent, an optional adhesive, and any other components in a solvent and stirring the mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

[0091] [Electrolyte]

[0092] The secondary battery 5 further includes an electrolyte.

[0093] The electrolyte serves to conduct ions between the positive plate 522 and the negative plate 521. The present application is not specifically limited to the type of electrolyte, which can be selected according to needs. For example, the electrolyte may be liquid, gel, or all solid.

[0094] In some embodiments, the electrolyte employs an electrolyte solution, the electrolyte solution including an electrolyte salt and a solvent.

[0095] In some embodiments, the electrolyte employs an electrolyte solution, the electrolyte solution including an electrolyte salt and a solvent.

[0096] By way of example, the lithium salt may include one or a combination of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0097] By way of example, the organic solvent may comprise one or a combination of more selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), diethyl sulfone (ESE).

[0098] In some embodiments, the electrolyte solution optionally further includes additives. For example, the additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some performance of the battery, such as an additive that improves the overcharge performance of the battery, an additive that improves the high temperature or low temperature performance of the battery, etc.

[0099] [Separator]

[0100] The secondary battery further includes a separator 523 .

[0101] In some embodiments, the secondary battery 5 further includes a separator 523. The present application is not particularly limited to the type of the separator 523, and any known separator 523 with a porous structure having good chemical stability and mechanical stability may be selected.

[0102] In some embodiments, the material of the separator 523 may be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator 523 may be a single-layer film or a multi-layer composite film, and there is no particular limitation. When the separator 523 is a multi-layer composite film, the materials of each layer may be the same or different, and there is no particular limitation.

[0103] As shown in FIG. 8, in some embodiments, the positive plate 522, the negative plate 521 and the separator 523 may be fabricated into an electrode assembly 52 by a winding process or a lamination process.

[0104] The present application is not particularly limited to the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, FIG. 9 shows a secondary battery 5 having a rectangular structure as an example.

[0105] In some embodiments, as shown in FIG. 9 and FIG. 10, the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected on the bottom plate, and the bottom plate and the side plate surround the case 51 to form a receiving cavity. The case 51 has an opening communicating with the receiving cavity, and the cover plate 53 is provided to cover the opening and close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator may form an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is permeated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and may be adjusted according to demand.

[0106] The method for manufacturing the secondary battery 5 of the present application is known. In some embodiments, the secondary battery 5 may be formed by assembling a positive electrode plate, a separator, a negative electrode plate, and an electrolyte. For example, an electrode assembly may be formed by a winding process or a lamination process using a positive electrode plate, a separator, and a negative electrode plate, and the electrode assembly is placed in an outer casing, dried, and then injected with an electrolyte, followed by vacuum packaging, standing, chemical conversion, shaping, and other processes to obtain the secondary battery 5.

[0107] In some embodiments of the present application, the secondary battery 5 according to the present application may be assembled into a battery module, and the number of secondary batteries 5 included in the battery module may be multiple, and the specific number can be adjusted based on the application and capacity of the battery module.

[0108] Fig. 11 is a schematic diagram of an example battery module 4. As shown in Fig. 11, in the battery module 4, the multiple secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the multiple secondary batteries 5 may be fixed with fasteners.

[0109] Optionally, the battery module 4 may further include a housing having an accommodating space, and the multiple secondary batteries 5 are accommodated in the accommodating space.

[0110] In some embodiments, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted based on the application and capacity of the battery pack.

[0111] 12 and 13 are schematic diagrams of an example battery pack 1. As shown in FIGS. 12 and 13, 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 is provided to cover the lower housing 3 and is used to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box according to any manner.

[0112] power consumption equipment

[0113] According to a fourth aspect, the present application provides a power consumption device, the power consumption device includes at least one of the secondary battery, the battery module, and the battery pack of the present application. The secondary battery, the battery module, and the battery pack may be used as a power source for the power consumption device, or may be used as an energy storage unit for the power consumption device. The power consumption device may be, but is not limited to, a mobile device (e.g., a mobile phone, a laptop, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0114] As the power consuming device, a secondary battery, a battery module, or a battery pack can be selected according to the demands of the usage.

[0115] 14 is a schematic diagram of an example power consuming device 6, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. A battery pack 1 or a battery module can be employed to meet the high power and high energy density demands of the power consuming device.

[0116] Another example of the power consuming device may be a mobile phone, a tablet computer, a notebook computer, etc. The power consuming device is generally required to be lightweight and may employ a secondary battery as a power source.

[0117] Working Example

[0118] The following describes the embodiments of the present application. The embodiments described below are illustrative and are merely for interpreting the present application, and should not be understood as limitations on the present application. If no specific techniques or conditions are specified in the embodiments, they will be performed according to the techniques or conditions described in the technical literature or the product instructions. Reagents or instruments used that do not specify the manufacturer are all common products that can be purchased commercially.

[0119] Example 1

[0120] 1. Manufacturing of positive electrodes

[0121] An aluminum foil with a thickness of 12 μm was used as the positive electrode current collector.

[0122] The positive electrode active material, the conductive agent carbon black, and the adhesive polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:1.4:1.1 in an appropriate amount of NMP solvent with sufficient stirring to form a uniform positive electrode slurry. The positive electrode slurry was then evenly coated on the surface of the aluminum foil positive electrode current collector, dried, and cold pressed to obtain a positive electrode plate.

[0123] 2. Manufacturing of negative electrodes

[0124] A copper foil with a thickness of 8 μm was used as the negative electrode current collector.

[0125] A positive photosensitive paste (specific components include epoxy resin DER331J, polyurethane modified epoxy resin EPU-10, acrylic acid, oxalic anhydride, benzyltriethylammonium chloride, hydroquinone, phthalic anhydride and benzoin ethyl ether) was coated on the negative electrode current collector at a coating speed of 50 m / min. After coating, the paste was baked in an oven at a baking temperature of 60°C for a baking time of 120 s. The photosensitive paste was hardened to obtain a photosensitive layer.

[0126] Cover with a mask plate, and the total light quantity is 65mj / cm 2 The photosensitive layer was irradiated with ultraviolet light (wavelength 365 nm) for 5 s. The mask plate was a metal template with a circular hole, the hole diameter was 2 mm.

[0127] The exposed photosensitive paste was sprayed with a developer, tetramethylammonium hydroxide, at a spray speed of 20-70 m / min and a flow rate of 0.1-1 L / min, to dissolve and wash away the exposed areas of the positive photosensitive paste, leaving behind an array of cylinders in the photosensitive layer.

[0128] The developed photosensitive layer was heat-treated at a temperature of 250° C. for a time of 10 minutes.

[0129] The negative electrode active material, artificial graphite, the conductive agent, carbon black, the adhesive, styrene butadiene rubber (SBR), and the thickener, sodium carboxymethylcellulose (CMC), were mixed in a weight ratio of 96.8:0.7:1.3:1.2 in an appropriate amount of deionized water as a solvent and thoroughly stirred to form a uniform negative electrode slurry. The negative electrode slurry was then applied into the pores of the photosensitive layer, and the negative electrode film layer was formed through drying and cold pressing.

[0130] An HF / HNO3 solution (with a concentration of 3 wt% / 20 wt%) buffered with H2O was used, which reacted with the photosensitive paste in the negative plate for 50 s to dissolve the photosensitive paste. After the treatment, a first hole was present in the negative electrode film layer, and the negative electrode film layer with the first hole and the negative electrode current collector formed a negative electrode plate.

[0131] 3. Separator

[0132] A porous polyethylene (PE) membrane was used as the separator.

[0133] 4. Electrolyte production

[0134] In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate (EC) and diethyl carbonate (DMC) were mixed in a volume ratio of 1:1 to obtain an electrolyte solvent, and then a lithium salt was mixed with the mixed solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0135] 5. Manufacturing of secondary batteries

[0136] A positive electrode plate, a separator, and a negative electrode plate are stacked in this order, with the separator positioned between the positive electrode plate and the negative electrode plate to perform an isolating function, and then wound to obtain an electrode assembly. The electrode assembly is placed in an outer casing, dried, and then an electrolyte is injected. After vacuum packaging, standing, chemical formation, shaping, and other processes, a lithium-ion battery is obtained.

[0137] Example 2

[0138] Lithium ion batteries were manufactured using a method similar to that of Example 1. The difference from Example 1 is that in Examples 2-1 to 2-3, in the process of manufacturing the negative electrode plate, the depth of the holes was adjusted by adjusting the reaction time between the HF / HNO3 solution buffered with H2O and the photosensitive layer in the negative electrode plate.

[0139] Comparative Example 1

[0140] In Comparative Example 1, a lithium ion battery was manufactured using a method similar to that of Example 1, but the difference from Example 1 was that in Comparative Example 1, the manufacturing process of the negative plate was adjusted as follows.

[0141] A copper foil with a thickness of 8 μm was used as the negative electrode current collector.

[0142] The negative electrode active material, artificial graphite, the conductive agent, carbon black, the adhesive, styrene butadiene rubber (SBR), and the thickener, sodium carboxymethylcellulose (CMC), were mixed in a weight ratio of 96.8:0.7:1.3:1.2 in an appropriate amount of deionized water as a solvent and stirred thoroughly to form a uniform negative electrode slurry. The negative electrode slurry was applied onto the surface of the negative electrode current collector, dried, and cold pressed to form a negative electrode film layer.

[0143] The relevant parameters of Example 1, Example 2 and Comparative Example 1 are as shown in Table 1.

[0144] [Table 1]

[0145] In Table 1, glue removal time is the reaction time between the HF / HNO3 solution buffered with H2O and the photosensitive layer on the negative plate. H1 represents the size of the first hole along the thickness direction of the negative plate (depth of H1). H represents the size of the negative film layer along the thickness direction of the negative plate (thickness of H).

[0146] As can be seen from Table 1, the negative electrode membrane layer of Comparative Example 1 is not artificially pore-formed, which has the risk of concentration polarization, poor dynamic performance, and poor fast charging performance. Compared with Comparative Example 1, the embodiment of the present application forms holes through an etching process, which can reduce the risk of concentration polarization and improve the dynamic performance, thereby improving the fast charging performance and safety performance.

[0147] Example 3

[0148] Example 3 employs a method similar to that of Example 1 to manufacture a lithium ion battery, and is different from Example 1 in that Examples 3-1 to 3-6 adjust the specifications of the mask plate, which affects the hole diameter parameters of the first hole.

[0149] The relevant parameters for Examples 1 and 3 are shown in Table 2.

[0150] [Table 2]

[0151] As can be seen from Table 2, by adjusting the specifications of the mask plate, the pore structure in the negative electrode film layer can be adjusted, thereby adjusting the fast charging ability and safety performance of the secondary battery.

[0152] Example 4

[0153] In Example 4, a lithium ion battery is manufactured by a method similar to that of Example 1. The difference from Example 1 is that in the process of manufacturing the negative electrode plate in Example 4, no heat treatment is performed after development. The specific manufacturing process of the negative electrode plate is as follows:

[0154] A copper foil with a thickness of 8 μm was used as the negative electrode current collector.

[0155] A positive photosensitive paste (specific components include epoxy resin DER331J, polyurethane modified epoxy resin EPU-10, acrylic acid, oxalic anhydride, benzyltriethylammonium chloride, hydroquinone, phthalic anhydride and benzoin ethyl ether) was coated on the negative electrode current collector at a coating speed of 50 m / min. After coating, the paste was baked in an oven at a baking temperature of 60°C for a baking time of 120 s. The photosensitive paste was hardened to obtain a photosensitive layer.

[0156] Cover with a mask plate, light intensity 65mj / cm 2The photosensitive layer was irradiated with ultraviolet light (wavelength 365 nm) for 5 s. The mask plate was a metal template with a circular hole, the hole diameter was 2 mm.

[0157] The exposed photosensitive paste was sprayed with a developer, tetramethylammonium hydroxide, at a spray speed of 20-70 m / min and a flow rate of 0.1-1 L / min, to dissolve and wash away the exposed areas of the positive photosensitive paste, leaving behind an array of cylinders in the photosensitive layer.

[0158] The negative electrode active material, artificial graphite, the conductive agent, carbon black, the adhesive, styrene butadiene rubber (SBR), and the thickener, sodium carboxymethylcellulose (CMC), were mixed in a weight ratio of 96.8:0.7:1.3:1.2 in an appropriate amount of deionized water as a solvent and thoroughly stirred to form a uniform negative electrode slurry. The negative electrode slurry was then applied into the pores of the photosensitive layer, and the negative electrode film layer was formed through drying and cold pressing.

[0159] An HF / HNO3 solution (with a concentration of 3 wt% / 20 wt%) buffered with H2O was used, which reacted with the photosensitive layer in the negative plate for 60 s to dissolve the photosensitive paste, and after the treatment, a first hole was present in the negative electrode film layer. The negative electrode film layer with the first hole and the negative electrode current collector formed a negative electrode plate.

[0160] The relevant parameters of Examples 1 and 4 are shown in Table 3.

[0161] [Table 3]

[0162] As can be seen from Table 3, in Example 4, no heat treatment was performed after the photosensitive layer was formed, whereas in Example 1, heat treatment was performed, which caused further cross-linking in the photosensitive layer and improved the bonding strength between the negative electrode current collector and the photosensitive layer, thereby increasing the structural stability inside the negative electrode plate and making interlayer delamination less likely to occur, which is advantageous for improving the rapid charging performance of the secondary battery.

[0163] Test part

[0164] 1. Negative plate parameter test

[0165] 1. The thickness H of the negative electrode film layer and the depth H1 of the first hole

[0166] A micrometer was used to measure the thickness of the negative plate at at least 12 different positions along the thickness direction of the negative plate, and the average value was taken as the thickness h1 of the negative plate, and the thickness of the negative current collector was subtracted to obtain the thickness of the negative film layer.

[0167] 2. The diameter, depth H1 and distance between two adjacent first holes of the first hole

[0168] A scanning electron microscope SEM (the model number of the SEM is Thermo Scientific Apreo 2) may be employed for observation.

[0169] Second, secondary battery parameter test

[0170] 1. Secondary battery fast charging performance test

[0171] At 25°C, the secondary battery prepared above was charged at a constant current of 0.33C up to a charge cut-off voltage of 4.4V, then charged at a constant voltage until the current reached 0.05C, allowed to stand for 5 minutes, and further discharged at a constant current of 0.33C up to a discharge cut-off voltage of 2.8V, and the actual capacity was recorded as C0.

[0172] Then, the secondary battery was charged at constant currents of 0.5C0, 1C0, 1.5C0, 2C0, 2.5C0, 3C0, 3.5C0, 4C0, and 4.5C0 in sequence up to a full battery charge cut-off voltage of 4.4V, and each time charging was completed, it was discharged at 1C0 down to a full battery discharge cut-off voltage of 2.8V, and discharged at different charge rates of 10%, 20%, 30%……80% SOC (State of Charge). The negative electrode potential corresponding to the charging up to 10% SOC (charge, charged state) was recorded, rate-negative electrode potential curves were created at different SOC states, and linear approximation was performed to obtain the charge rate corresponding to the negative electrode potential of 0V at different SOC states. The charge rate is the charge window at the SOC state, which is C10% SOC, C20% SOC, C30% SOC, C40% SOC, C50% SOC, C60% SOC, C70% SOC, and C80% SOC, respectively. The charging time T for charging the secondary battery from 10% SOC to 80% SOC was calculated according to the formula (60 / C20% SOC+60 / C30% SOC+60 / C40% SOC+60 / C50% SOC+60 / C60% SOC+60 / C70% SOC+60 / C80% SOC)×10%. The shorter the charging time T, the better the rapid charging performance of the secondary battery.

[0173] Although the present application has been described with reference to the preferred embodiments, various improvements may be made thereto and the elements therein may be replaced with equivalents without departing from the scope of the present application. In particular, the respective technical features mentioned in each embodiment may be combined in any manner, as long as there is no structural contradiction. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions included in the claims.

[0174] The explanation of the symbols is as follows: 1, battery pack, 2, upper housing, 3, lower housing, 4, battery module, 5, secondary battery, 51, case, 52, electrode assembly, 521, negative electrode plate, 5211, negative electrode current collector, 5212, negative electrode film layer, 5213, first hole, 5214, photosensitive layer, 52141, recess, 5215, mask plate, 522, positive electrode plate, 523, separator, 53, cover plate, 6, power consumption equipment.

Claims

1. A method for manufacturing a negative electrode plate, comprising: Providing a negative electrode current collector; applying a photosensitive paste onto at least one surface of the negative electrode current collector and curing the paste to form a photosensitive layer; patterning light into a predetermined pattern and directing the light to enter the photosensitive layer from a surface of the photosensitive layer remote from the negative electrode current collector to expose the photosensitive layer; developing the exposed photosensitive layer to obtain a photosensitive layer having recesses; filling the recess with an anode slurry and hardening the anode slurry to form an anode film layer; and removing at least a portion of the photosensitive layer to obtain the negative electrode plate.

2. The method of claim 1 , wherein the step of removing at least a portion of the photosensitive layer comprises removing the photosensitive layer for a time period between 10 s and 60 s.

3. The method further includes, after the step of developing the photosensitive layer, heat treating the developed photosensitive layer; 3. The method of claim 1 or 2, optionally wherein the temperature of the heat treatment is between 200° C. and 250° C., and / or the time of the heat treatment is between 10 min and 20 min.

4. In the step of applying a photosensitive paste onto at least one surface of the negative electrode current collector and curing the paste to form a photosensitive layer, (1) the coating speed is 20 m / min to 70 m / min; (2) The curing temperature is 60°C to 90°C; (3) The curing time is 60 s to 90 s; (4) The method according to any one of claims 1 to 3, wherein the photosensitive layer contains a positive-type photosensitive paste or a negative-type photosensitive paste.

5. The thickness of the photosensitive layer is T1 μm, the thickness of the negative electrode film layer is T2 μm, The method according to any one of claims 1 to 4, wherein 1.0≦T1 / T2≦1.

5.

6. The step of patterning light into a predetermined pattern and exposing the photosensitive layer by making the light incident on the photosensitive layer from a surface of the photosensitive layer remote from the negative electrode current collector includes: using a mask plate to direct light to the photosensitive layer from a surface of the photosensitive layer remote from the negative electrode current collector to expose the photosensitive layer; Optionally, the method further comprises: (I) the exposure time is 1 s to 10 s; (II) the mask plate includes a plurality of holes, and the holes have a diameter of 10 μm to 2500 μm; (III) The method according to any one of claims 1 to 5, wherein at least one of the following conditions is satisfied: a distance between the mask plate and the photosensitive layer is 0 to 400 μm, and optionally 0 to 200 μm.

7. The method according to any one of claims 1 to 6, wherein the anode slurry comprises an anode active material, and the anode active material comprises one or more of artificial graphite, natural graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate.

8. A negative electrode plate manufactured by the method according to any one of claims 1 to 7, A negative electrode current collector; a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a first hole; Where: The size of the first hole along the thickness direction of the negative electrode plate is H 1 μm; The size of the negative electrode film layer along the thickness direction of the negative electrode plate is H μm; Optionally, 0.2≦H1 / H≦1.0, and further optionally, 0.5≦H1 / H≦1.

0.

9. The negative electrode plate is (a) a diameter of the first hole is D μm, 10≦D≦500, and optionally, 10≦D≦100; (b) 10≦H1≦300; and (c) 50≦H≦300. The negative electrode plate according to claim 8 .

10. The negative electrode plate according to claim 8 or 9, wherein a plurality of the first holes are provided, the plurality of first holes are provided at intervals, and the interval between two adjacent first holes is W μm, where 100≦W≦1000, and optionally 100≦W≦200.

11. A secondary battery comprising the negative electrode plate according to any one of claims 8 to 10.

12. A power consuming device comprising the secondary battery of claim 11.

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