CN116759531A

CN116759531A - Negative electrode plate, battery cell, battery and electricity utilization device

Info

Publication number: CN116759531A
Application number: CN202310028114.6A
Authority: CN
Inventors: 任莹莹; 王曦童; 唐代春; 杜鑫鑫
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-01-09
Filing date: 2023-01-09
Publication date: 2023-09-15

Abstract

The application provides a negative electrode plate, a battery cell, a battery and an electric device. The negative electrode plate comprises a negative electrode current collector and a film layer arranged on at least one surface of the negative electrode current collector, wherein the film layer comprises pores, and the pore diameter of the pores on the upper surface of the film layer is larger than the pore diameter of the pores on the lower surface of the film layer. The application can accelerate the lithium ion in the electrolyte to be inserted into the anode material and rapidly transmitted to the deep part of the pore, thereby obviously improving the rapid charging performance and the cycle performance of the anode pole piece and the battery.

Description

Negative electrode plate, battery cell, battery and electricity utilization device

Technical Field

The application relates to the technical field of batteries, in particular to a negative electrode plate, a battery cell, a battery and an electric device.

Background

In recent years, with increasing demands for clean energy and rapid development of new energy fields, batteries are widely applied to energy storage power supply systems of hydraulic power, firepower, wind power, solar power stations and the like, and various fields of electric tools, electric bicycles, electric motorcycles, electric automobiles, military equipment, aerospace and the like. As batteries have evolved greatly, higher demands are also being made on their performance.

In order to further improve the user experience, how to improve the quick charge performance and the cycle performance of the battery, shorten the charge time and prolong the service life of the battery has become a technical problem to be solved.

Disclosure of Invention

The present application has been made in view of the above problems, and an object thereof is to provide a negative electrode tab, a battery cell, a battery, and an electric device having significantly improved quick charge performance and cycle performance.

In order to achieve the above object, according to a first aspect, some embodiments of the present application provide a negative electrode tab, including a negative electrode current collector and a membrane layer disposed on at least one surface of the negative electrode current collector, wherein the membrane layer includes pores, and a pore diameter of the pores on an upper surface of the membrane layer is larger than a pore diameter of the pores on a lower surface of the membrane layer.

The pore diameter of the pore on the upper surface of the film layer is larger than that of the pore on the lower surface of the film layer, so that lithium ions in the electrolyte can be accelerated to be embedded into the anode material and rapidly transmitted to the deep part of the pore, the lithium embedding amount of the anode plate is more uniform, the utilization rate of lithium is improved, and the quick charge performance and the cycle performance of the battery cell are improved.

In some embodiments, the pore diameter D2 at 3/4 of the thickness of the membrane layer from the anode current collector surface is greater than the pore diameter D1 at 1/4 of the thickness of the membrane layer from the anode current collector surface.

D2 is larger than D1, can improve lithium ion transmission rate, reduce the emergence of negative pole piece "lithium evolution" to a great extent, be favorable to the quick charge performance and the cycle performance of battery.

In some embodiments, the ratio of D2 to D1 is 1.2:1-3.5:1, alternatively 1.5:1-3.0:1.

the D2/D1 satisfies the relation of the pore diameter ratio, so that the efficiency of lithium ion transmission to the deep part of the pore can be further improved, the utilization rate of lithium is improved, and the performances of the negative electrode plate and the battery are further improved.

In some embodiments, D2 is 48-140 μm, optionally 60-120 μm.

In some embodiments, D1 is 5-60 μm, optionally 30-60 μm.

When the pore diameters D2 and D1 are respectively in the above ranges, the lithium intercalation amount of the negative electrode plate can be more uniform, and the utilization rate of lithium is higher, so that the quick charge performance and the cycle performance of the negative electrode plate and the battery cell are improved, and the problems of 'lithium precipitation' and the like are avoided or alleviated.

In some embodiments, the adjacent pores have a pore spacing between the upper surface of the membrane layer of 100-300 μm.

When the hole spacing is in the range, the transmission efficiency of lithium ions can be improved, and electrolyte is facilitated to infiltrate the negative electrode plate, so that the quick charging performance and the cycle performance of the battery are improved.

In some embodiments, the thickness M0 of the film layer is 50-280 μm, optionally 80-180 μm.

When the thickness of the film layer is within the above range, the battery quick charge performance and cycle performance can be improved while satisfying the existing process feasibility.

In some embodiments, the aperture is inverted conical or inverted frustoconical.

When the pore is in an inverted conical shape or an inverted truncated cone shape, the rapid charging capability and the cycle performance of the battery can be improved, and meanwhile, the processing is convenient.

In some embodiments, the membrane layer includes a first anode material layer disposed on at least one surface of the anode current collector and a second anode material layer disposed on a surface of the first anode material layer.

In some embodiments, the film layer includes a negative electrode active material including at least one of soft carbon, hard carbon, graphite, silicon, a silicon oxygen compound, a silicon carbon composite, and a metal capable of forming an alloy with lithium.

The adoption of the negative electrode active material in the range can be beneficial to improving the quick charge performance and the cycle performance of the battery while meeting the capacity of the battery.

In a second aspect, some embodiments of the present application provide a battery cell including the negative electrode tab of the above embodiment.

In a third aspect, some embodiments of the present application provide a battery comprising the battery cells of the above embodiments.

In a fourth aspect, some embodiments of the present application provide an electrical device comprising a battery cell as in the above embodiment or a battery as in the above embodiment.

The foregoing description is only an overview of the present application, and is intended to provide a better understanding of the technical means of the present application, as it is embodied in accordance with the present application, and is intended to provide a better understanding of the above and other objects, features and advantages of the present application, as it is embodied in the following specific examples.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of a first negative electrode tab provided in some embodiments of the application;

FIG. 2 is a schematic illustration of a second negative electrode tab provided in some embodiments of the application;

FIG. 3 is a schematic view of a third negative electrode tab provided in some embodiments of the application;

FIG. 4 is a schematic illustration of an electrode assembly provided in some embodiments of the application;

FIG. 5 is a schematic illustration of a battery cell provided in some embodiments of the application;

fig. 6 is an exploded view of a battery cell provided in some embodiments of the application shown in fig. 5;

fig. 7 is a schematic view of a battery module provided in some embodiments of the application;

FIG. 8 is a schematic illustration of a battery pack provided in some embodiments of the application;

fig. 9 is an exploded view of a battery pack provided in some embodiments of the application shown in fig. 8;

fig. 10 is a schematic diagram of an electric device according to some embodiments of the present application.

Reference numerals illustrate:

1, a battery pack; 2, upper box body; 3, lower box body; 4, a battery module; 5, a battery cell; 51 a housing; 52 electrode assembly; 53 cover plates; 521 negative pole piece; 522 a separator; 523 positive pole piece; 5211 negative electrode current collector; 5212 film layer; 5213 pores; 52121 a first layer of negative electrode material; 52122 a second layer of negative electrode material.

Detailed Description

Hereinafter, embodiments of the negative electrode tab, the battery cell, the battery and the power utilization device of the present application are specifically disclosed with reference to the accompanying drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.

The "range" disclosed herein is defined in terms of lower and upper limits, with the given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can 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 contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.

All embodiments of the application and alternative embodiments may be combined with each other to form new solutions, unless otherwise specified.

All technical features and optional technical features of the application may be combined with each other to form new technical solutions, unless specified otherwise.

All the steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise specified. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which 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), and the like.

The terms "comprising" and "including" as used herein mean open ended or closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.

The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).

The more widely the application of power cells is seen from the development of market situation. The power battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles, and the like, and a plurality of fields such as military equipment, aerospace, and the like. With the continuous expansion of the application field of the power battery, the market demand of the power battery is also continuously expanding.

At present, after batteries are widely applied to new energy automobiles, people put forward higher demands on the charging duration and service life of the new energy automobiles. This requirement translates into a requirement for battery fast charge performance and cycle performance. High battery capacity can employ a negative electrode active material having high battery capacity, but in most cases the quick charge performance and cycle performance of the battery are not improved so much.

Therefore, how to design a negative electrode plate can significantly improve the quick charge performance and the cycle performance of the battery is a problem to be solved in the field of batteries.

Based on the above, the application provides a negative electrode plate, and a battery cell, a battery and an electric device comprising the negative electrode plate.

[ negative electrode sheet ]

Referring to fig. 1, the negative electrode tab 521 includes a negative electrode current collector 5211 and a negative electrode film layer 5212 disposed on at least one surface of the negative electrode current collector 5211, the negative electrode film layer 5212 including a negative electrode active material.

As an example, the anode current collector 5211 has two surfaces opposing in its own thickness direction, and the anode film layer 5212 is provided on either or both of the two opposing surfaces of the anode current collector 5211.

In some embodiments, the negative current collector 5211 may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. 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 base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the negative active material may employ a negative active material for a battery, which is well known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like. The silicon-based material may be at least one selected from elemental silicon, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based material may be at least one selected from elemental tin, tin oxide, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments, the negative electrode film layer 5212 also optionally includes a binder. The binder may be at least one selected from 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).

In some embodiments, the negative electrode film layer 5212 can also optionally include a conductive agent. The conductive agent is at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

In some embodiments, the negative electrode film layer 5212 can optionally also include other adjuvants, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

In some embodiments, the negative electrode tab 521 may be prepared by: dispersing the above components for preparing the negative electrode tab 521, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on a negative electrode current collector 5211, and the negative electrode plate 521 is obtained after the processes such as drying and cold pressing.

Referring to fig. 1, in a first aspect, some embodiments of the present application provide a negative electrode tab 521, including a negative electrode current collector 5211 and a membrane layer 5212 disposed on at least one surface of the negative electrode current collector 5211, the membrane layer 5212 including an aperture 5213, wherein a diameter of the aperture 5213 on an upper surface of the membrane layer 5212 is greater than a diameter of the aperture 5213 on a lower surface of the membrane layer 5212.

The upper and lower surfaces of the membrane layer 5212 are divided into an upper surface of the membrane layer 5212 and a lower surface of the membrane layer 5212 according to the relative length from the surface of the membrane layer 5212 in contact with the negative electrode current collector 5211. The pores 5213 form a three-dimensional structure having a certain space inside the membrane layer 5212. The aperture 5213 extends through the upper and lower surfaces of the membrane layer 5212 as a unit. The diameter of the aperture 5213 at the upper surface of the membrane layer 5212 refers to the diameter of the cross-sectional circle of the aperture 5213 at the upper surface of the membrane layer 5212 in μm. The diameter of the aperture 5213 at the lower surface of the membrane layer 5212 refers to the diameter of the cross-sectional circle of the aperture 5213 at the lower surface of the membrane layer 5212 in μm. Pore diameter was measured using test methods well known in the art. For example, reference is made to national standard JY/T010-1996, which was tested using an analytical scanning electron microscope.

The pore diameter of the pore 5213 on the upper surface of the membrane layer 5212 is larger than that of the pore 5213 on the lower surface of the membrane layer 5212, so that lithium ions in the electrolyte can be accelerated to be embedded into a negative electrode material and rapidly transferred to the depth of the pore 5213, the lithium embedding amount of the negative electrode plate 521 is more uniform, the utilization rate of lithium is improved, and the quick charging performance and the cycle performance of the battery cell 5 are improved.

In some embodiments, the pore diameter D2 of the membrane layer 5212 at 3/4 of the membrane layer thickness from the surface of the negative electrode current collector 5211 is greater than the pore diameter D1 of the membrane layer 5212 at 1/4 of the membrane layer thickness from the surface of the negative electrode current collector 5211. D2 is the diameter of the cross-sectional circle where the height of the aperture 5213 parallel to the surface of the negative current collector 5211 is 3/4 of the thickness of the membrane layer in μm. D1 is the diameter of the cross-sectional circle where the height of the aperture 5213 parallel to the surface of the negative current collector 5211 is 1/4 of the thickness of the membrane layer in μm.

D2 is larger than D1, which can improve the lithium ion transmission rate, greatly reduce the occurrence of lithium precipitation of the negative electrode plate 521, and is beneficial to the quick charge performance and the cycle performance of the battery.

In some embodiments, the ratio of D2 to D1 is 1.2:1-3.5:1, alternatively 1.5:1-3.0:1. as an example, the value of D1/D2 may be 1.2: 1. 1.5: 1. 2.0: 1. 2.5: 1. 3.0:1. 3.5:1 or any value within the numerical range of any two compositions.

The D2/D1 satisfies the relationship of the pore diameter ratio, so that the efficiency of lithium ion transmission to the deep part of the pore 5213 can be further improved, the utilization rate of lithium is improved, and the performances of the negative electrode plate 521 and the battery are further improved. The D2/D1 is smaller than 1.2, and the transmission efficiency of lithium ions is slower. The D2/D1 is larger than 3.5, D2 is larger, the space occupied by the pore 5213 in the film 5212 is larger, and the capacity of the negative electrode plate 521 is reduced.

In some embodiments, D2 is 48-140 μm, optionally 60-120 μm. By way of example, the value of D2 may be any value within a range of values consisting of 48 μm, 60 μm, 80 μm, 90 μm, 120 μm, 140 μm, or any two.

When D2 is less than 48 μm, the transmission rate of lithium ions upon charging becomes lower by the influence thereof, affecting the rapid charging performance and cycle performance of the battery cell 5; when D2 is greater than 140 μm, the negative electrode active material is less, and the battery capacity is affected.

In some embodiments, D1 is 5-60 μm, optionally 30-60 μm. By way of example, the value of D1 may be any value within a range of values consisting of 5 μm, 16 μm, 24 μm, 30 μm, 32 μm, 40 μm, 60 μm, or any two.

When D1 is smaller than 5 μm, lithium ions are difficult to transmit to the deep part of the pores 5213, and the lower surface of the membrane layer 5212 cannot be rapidly charged; when D1 is larger than 60 μm, the negative electrode tab 521 is liable to "lithium precipitation", and the charge rate and cycle number of the battery cell 5 become small.

When the pore diameters D2 and D1 are respectively within the above ranges, the lithium intercalation amount of the negative electrode plate 521 can be more uniform, and the utilization rate of lithium is higher, so that the quick charge performance and the cycle performance of the negative electrode plate 521 and the battery cell 5 are improved, and the problems of 'lithium precipitation' and the like are avoided or alleviated.

In some embodiments, the pore spacing between adjacent pores 5213 between the upper surfaces of the membrane layers 5212 is from 100 to 300 μm. Adjacent apertures 5213 are any one aperture 5213 and another aperture 5213 on the upper surface of the membrane layer 5212 closest to the aperture 5213. The hole spacing is the distance in μm between the centers of two holes of two adjacent holes 5213 on the upper surface of the membrane layer 5212. The hole spacing may be measured using test methods known in the art. For example, reference is made to national standard JY/T010-1996, which was tested using an analytical scanning electron microscope. As an example, the value of the hole spacing may be any value within a numerical range of 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, or any two of the compositions.

When the hole spacing is larger than 300 mu m, the distance interval between the centers of adjacent holes on the upper surface of the film 5212 is far, the number of holes per unit area is small, and the rate of transmitting lithium ions to the bottom of the film is influenced, so that the quick charge performance and the cycle performance of the battery are reduced; when the hole pitch is less than 100 μm, the negative electrode tab 521 is liable to be problematic in "lithium precipitation" or the like, thereby having a small charge rate and cycle number. In addition, when the hole spacing is within the scope of the application, the difficulty of the electrolyte to infiltrate the negative electrode plate 521 is improved, and the quick charge performance and the cycle performance of the battery are improved.

In some embodiments, the thickness M0 of the membrane layer 5212 is 50-280 μm, alternatively 80-180 μm. The thickness of the membrane layer 5212 is the distance from the upper surface of the membrane layer 5212 to the surface of the negative electrode current collector 5211 in μm. The thickness of the membrane layer 5212 is measured using test methods known in the art. As an example, the test measurement was performed using a laser thickness gauge. As an example, the thickness of the film layer 5212 can be any value within a numerical range of 50 μm, 80 μm, 100 μm, 150 μm, 180 μm, 200 μm, 250 μm, 280 μm, or any two of the above.

When the thickness M0 of the film 5212 is less than 50 μm, problems such as wrinkling and metal leakage easily occur in the process of preparation by the existing process. When the thickness M0 of the membrane layer is greater than 280 μm, lithium ions on the surface of the membrane layer 5212 are difficult to be inserted into the bottom, reducing the rapid charge performance and cycle performance of the battery cell 5. When the thickness of the film layer 5212 is within the above range, the quick charge property and the cycle property can be improved while satisfying the existing process feasibility.

In some embodiments, the aperture 5213 is inverted conical or frustoconical. Referring to fig. 1 and 2, the aperture 5213 is of an inverted conical shape, which is of an inverted vertical conical shape. Referring to fig. 3, the aperture 5213 is inverted truncated cone shaped and the inverted truncated cone shaped is vertically inverted.

The reverse conical shape or the reverse round table shape is convenient to process, and meanwhile, the quick charge performance and the circulation performance of the battery cell 5 are improved. The shape of the aperture 5213 is measured by an analytical Scanning Electron Microscope (SEM), specifically, as seen in an electron microscope image taken by the SEM.

Referring to fig. 2 and 3, in some embodiments, the film layer 5212 includes a first anode material layer 52121 disposed on at least one surface of the anode current collector 5211 and a second anode material layer 52122 disposed on a surface of the first anode material layer 52121.

In some embodiments, the membrane layer 5212 includes a negative electrode active material including at least one of soft carbon, hard carbon, graphite, silicon, a silicon oxygen compound, a silicon carbon composite, and a metal capable of forming an alloy with lithium.

The adoption of the negative electrode active material in the range is beneficial to improving the quick charge performance and the cycle performance of the battery while meeting the capacity of the battery.

In addition, the inventors of the present application have found through a large number of experiments that setting D2/D1, D2, and D1 within the above ranges, respectively, can further improve the quick charge performance and the cycle performance of the negative electrode tab 521 and the battery cell 5.

In a second aspect, some embodiments of the present application provide a battery cell 5 comprising a negative electrode tab 521 as in the previous embodiments.

In a third aspect, some embodiments of the present application provide a battery comprising a battery cell 5 as in the above embodiments.

In a fourth aspect, some embodiments of the present application provide an electrical device comprising a battery cell 5 as in the above embodiment or a battery as in the above embodiment.

In addition, the battery cell 5, the battery, and the electric device provided in the embodiment of the application are described below with appropriate reference to the drawings.

Referring to fig. 4, the electrode assembly 52 includes a negative electrode tab 521, a separator 522, and a positive electrode tab 523. The electrode assembly 52 is manufactured through a winding process, a lamination process, or the like.

[ Positive electrode sheet ]

The positive electrode tab 523 includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode film layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.

In some embodiments, the positive current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. 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 base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, when the battery cell 5 is a lithium ion battery, the positive electrode active material may be a positive electrode active material for lithium ion batteries, which is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Wherein, the liquid crystal display device comprises a liquid crystal display device, examples of the lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (e.g., liCoO 2), lithium nickel oxide (e.g., liNiO 2), lithium manganese oxide (e.g., liMnO2, liMn2O 4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel cobalt manganese oxide (e.g., liNi1/3Co1/3Mn1/3O2 (may also be abbreviated as NCM 333), lini0.5co0.2mn0.3o2 (may also be abbreviated as NCM 523), lini0.5co0.25mn0.25o2 (may also be abbreviated as NCM 211), lini0.6co0.2mn0.2o2 (may also be abbreviated as NCM 622), lini0.8co0.1mn0.1o2 (may also be abbreviated as NCM 811), lithium nickel cobalt aluminum oxide (e.g., lini0.85co0.15al0.15o2), and modified compounds thereof, and the like, and lithium phosphate may include, but are not limited to lithium iron phosphate (e.g., lithium iron phosphate, lithium carbonate, lithium phosphate, and the like, and lithium phosphate, lithium iron phosphate, lithium phosphate, and the like.

In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluoroacrylate resin.

In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an 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.

In some embodiments, the positive electrode sheet 523 may be prepared by: the above-described components for preparing the positive electrode sheet 523, such as the positive electrode active material, the conductive agent, the binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on a positive electrode current collector, and the positive electrode plate 523 can be obtained after procedures such as drying, cold pressing and the like.

[ isolation Membrane ]

In some embodiments, separator 522 is also included in electrode assembly 52. The type of the separator 522 is not particularly limited, and any known porous separator 522 having good chemical stability and mechanical stability may be used.

In some embodiments, the material of the isolation film 522 may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator 522 may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator 522 is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.

In some embodiments of the present application, a battery cell 5 is provided.

The battery cell 5 includes the above-described electrode assembly 52 and an electrolyte. The battery cells include, but are not limited to, lithium ion secondary batteries, lithium ion primary batteries, lithium sulfur batteries, sodium lithium ion batteries, sodium ion batteries, magnesium ion batteries, and the like.

Electrolyte the electrolyte acts to conduct ions between the positive pole piece 523 and the negative pole piece 521. The application is not particularly limited in the kind of electrolyte, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.

In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.

Taking lithium ion batteries as an example, 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 difluorooxalato borate, lithium difluorooxalato phosphate, and lithium tetrafluorooxalato phosphate.

In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl 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, methyl sulfone, and diethyl sulfone.

In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.

In some embodiments, the battery cell 5 may include an outer package. The overwrap may be used to encapsulate the electrode assembly 52 and electrolyte.

In some embodiments, the exterior packaging of the battery cell 5 may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The exterior package of the battery cell 5 may also be a pouch, such as a pouch-type pouch. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

The shape of the battery cell 5 is not particularly limited in the present application, and may be cylindrical, square, or any other shape. For example, fig. 5 is a square-structured battery cell 5 as one example.

In some embodiments, referring to fig. 6, the overpack may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 51 has an opening communicating with the accommodation chamber, and the cover plate 53 can be provided to cover the opening to close the accommodation chamber. The electrode assembly 52 is enclosed in the accommodating chamber. The electrolyte is impregnated in the electrode assembly 52. The number of the electrode assemblies 52 included in the battery cell 5 is one or more, and one skilled in the art may select according to specific practical requirements.

In some embodiments of the present application, a battery is provided.

A battery is a single physical module that includes one or more battery cells to meet the capacity requirements of the battery. For example, the battery mentioned in the embodiment of the present application includes the battery module 4 or the battery pack 1, or the like. The battery generally comprises a housing for enclosing one or more battery cells 5. The case can prevent liquid or other foreign matter from affecting the charge or discharge of the battery cell 5.

In some embodiments, the battery cells 5 are assembled into a battery module 4, and the number of battery cells included in the battery module is one or more, and the specific number can be selected by one skilled in the art according to the application and capacity of the battery module.

Fig. 7 is a battery module 4 as an example. Referring to fig. 7, in the battery module 4, a plurality of battery cells 5 may be sequentially arranged in the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of battery cells 5 may be further fixed by fasteners.

Alternatively, the battery module 4 may further include a housing having an accommodating space in which the plurality of battery cells 5 are accommodated.

In some embodiments, the battery modules may also be assembled into a battery pack that contains one or more battery modules. The battery cells can also be directly assembled into a battery pack, and the number of the battery cells contained in the battery pack is one or more. The specific number of battery modules or cells that a battery pack contains can be selected by one skilled in the art depending on the application and capacity of the battery pack.

Fig. 8 and 9 are battery packs 1 as an example. Referring to fig. 8 and 9, a battery case and a plurality of battery modules 4 disposed in the battery case are included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

In addition, in some embodiments of the present application, an electrical device is also provided.

The electricity utilization device comprises the battery monomer or the battery provided by the application. The battery cell or battery may be used as a power source for the power device and may also be used as an energy storage unit for the power device. The electric device includes mobile equipment (such as a mobile phone, a notebook computer, etc.), electric vehicles (such as 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.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

As the electricity consumption device, a battery cell or a battery is selected according to the use requirement thereof.

Fig. 10 is an electric device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. To meet the high power and high energy density requirements of the power device for the battery, a battery pack or battery module may be employed.

As another example, the device may be a cell phone, tablet computer, notebook computer, or the like. The device is generally required to be light and thin, and a battery cell can be used as a power supply.

Examples

Hereinafter, embodiments of the present application are described. The following examples are illustrative only and are not to be construed as limiting the application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

1. Preparation of Battery cell

[ preparation of negative electrode sheet ]

Mixing graphite serving as a first anode active material, carbon black serving as a conductive agent, sodium carboxymethyl cellulose (CMC-Na) serving as a dispersing agent and styrene-butadiene rubber (SBR) serving as a binder according to the mass ratio of 96.8:0.5:1.0:1.7, adding deionized water into the mixture, and uniformly mixing to obtain first anode material slurry with the solid content of 50% and the viscosity of 9000 mPa.s;

mixing the second anode active material graphite, the conductive agent carbon black, the dispersing agent sodium carboxymethyl cellulose and the adhesive styrene-butadiene rubber according to the mass ratio of 96.7:0.6:1.0:1.7, adding deionized water into the mixture, and uniformly mixing to obtain second anode material slurry with the solid content of 50% and the viscosity of 9000 mPa.s;

coating a first negative electrode material slurry on one surface of a negative electrode current collector copper foil (thickness 6 μm) by using a coater to prepare a first negative electrode material layer; and then coating a second anode material layer on the first anode material layer, wherein the coating weight of the first anode material layer and the second anode material layer is 0.066g/1540.25mm < 2 > (namely, the weight ratio of the second anode material layer to the first anode material layer is 1:1). The slurry was then coated on the other surface of the negative electrode current collector in the same order and method. After drying, the mixture is placed between two counter-rotating rollers for cold pressing, wherein conical protruding points are arranged on the surfaces of the two rollers. And then cutting to obtain the negative electrode plate with the inverted conical pore.

Fig. 2 is a schematic diagram of an anode piece according to an embodiment of the present application, where the film layer includes a first anode material layer and a second anode material layer, and the pore is in an inverted cone shape, and the pore diameter of the pore on the upper surface of the film layer is greater than the pore diameter of the pore on the lower surface of the film layer.

[ preparation of Positive electrode sheet ]

Active material ternary lithium NCM811, conductive agent carbon black and adhesive polyvinylidene fluoride (PVDF) are prepared according to the mass ratio of 97.5:1.0:0.5:1.0, dissolved in N-methyl pyrrolidone (NMP), stirred for 4 hours, the viscosity of the mixture is regulated to 10000 mPa.s by using NMP, and the mixture is uniformly stirred to obtain positive electrode slurry. And coating the positive electrode slurry on an aluminum foil, drying at 90 ℃, and then carrying out cold pressing and slitting to obtain the positive electrode plate.

[ electrolyte ]

Mixing Ethylene Carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) according to a volume ratio of 5:2:3, and preparing the mixture to be at a temperature of 25 ℃; then adding lithium hexafluorophosphate into the solution to prepare 1.0mol/L solution, thus obtaining the electrolyte.

[ isolation Membrane ]

Polyethylene film was used as the separator film.

[ preparation of lithium ion Battery monomer ]

And sequentially stacking the positive electrode plate, the isolating film and the negative electrode plate, enabling the isolating film to be positioned between the positive electrode plate and the negative electrode plate to play a role of isolation, then winding, welding the electrode lugs, loading the electrode lugs into an aluminum shell, baking at 105 ℃ for dewatering, injecting electrolyte and sealing to obtain the uncharged battery cell. And sequentially carrying out the working procedures of standing, hot and cold pressing, formation, shaping, capacity testing and the like on the uncharged battery monomer to obtain the lithium ion battery monomer.

2. Test method

[ pore diameter test ]

Referring to the national standard JY/T010-1996, the test was performed by using an analytical scanning electron microscope. The specific test steps are as follows:

(1) Sample preparation: a. and cutting the negative electrode plate into 6mm or 6mm by using ceramic scissors, attaching the negative electrode plate to a sample table smeared with paraffin, and slightly protruding the sample (< 1 mm) from the edge of the sample table. b. The polishing voltage (7.5 kV) and the polishing time (90 min) were set.

(2) Parameter setting: mode: in-lens; voltage: 10kV; a diaphragm: 30 μm; working distance: 4.5mm.

(3) And (3) testing: photographing 3 sheets under the magnification of 500 times (the field of view comprises a negative current collector and a film layer); the negative current collector is taken 5 places under the condition of taking the picture with the center and the magnification of 2000 times. Pore diameters were measured at 1/4 and 3/4 of the thickness of the membrane layer from the negative electrode current collector.

[ hole Interval test ]

(1) Sample preparation: and cutting a 5 mm-sized negative electrode plate sample by using a ceramic scissors, and pasting the negative electrode plate sample on a sample table adhered with conductive adhesive.

(3) And (3) testing: and (3) moving the negative electrode plate sample left and right under the magnification of 100 times, after confirming that the whole sample is not obviously abnormal, selecting two visual fields, taking 2 groups under the surface focusing magnification of 10k, 5k, 3k, 1k and 500 times, and measuring the hole spacing between the adjacent holes on the upper surface of the film layer.

[ test of thickness of film ]

During coating, alignment marks are arranged at the two ends of the upper surface and the lower surface of the film layer, and an on-line thickness measuring system (such as a laser thickness meter) is adopted to measure the thickness of the film layer.

[ test of the Charge Rate of Battery cell ]

And (3) fully charging the lithium ion battery monomer at the charging multiplying power of xC at 25 ℃, fully discharging the lithium ion battery monomer at the multiplying power of 1C for 10 times, fully charging the battery monomer at the charging multiplying power of xC, disassembling the negative electrode plate, and observing the lithium precipitation condition on the surface of the negative electrode plate. And if the lithium is not separated from the surface of the negative electrode plate, the charging multiplying power xC is gradually increased by 0.1C to carry out the test again until the lithium is separated from the surface of the negative electrode. At this time, the charging rate= (x-0.1) C is the maximum charging capacity of the battery cell at 25 ℃.

[ cycle number test of Battery cell ]

And (3) at 25 ℃, the lithium ion battery monomer is charged to a charge cut-off voltage V1 at a constant current of 1C, then is charged to a current of less than or equal to 0.05C at a constant voltage, is kept stand for 5min, is discharged to a discharge cut-off voltage V2 at a constant current of 0.33C, and is kept stand for 5min, so that the lithium ion battery is a charge-discharge cycle. And carrying out cyclic charge and discharge test on the battery cell according to the method until the capacity of the battery cell is attenuated to 80%. The cycle number at this time is the cycle life of the battery cell at 25 ℃.

3. Experimental conditions and test results

The parameters of the negative electrode tab and the electrochemical performance test results of the battery cells used in each experimental group are shown in table 1.

TABLE 1

The negative electrode sheet film thickness M0 of examples 1-15 and comparative examples 1, 2 was 120. Mu.m.

As can be seen from table 1:

the pore diameters of the pores on the upper surface of the membrane layer in examples 1-15 are larger than the pore diameters of the pores on the lower surface of the membrane layer, and compared with the pore diameters of the upper surface of the membrane layer equal to or smaller than the pore diameters of the lower surface of the membrane layer in comparative examples 1 and 2, the charging rate and the cycle number of the prepared battery monomer are obviously improved, which indicates that the battery monomers in examples 1-15 have better quick charge performance and cycle performance.

In examples 1 to 6, when the ratio of D2 to D1 was within a certain range, the charge rate and the number of cycles of the prepared battery cell were gradually increased as the ratio was gradually increased.

In examples 6, 11-14, when the hole spacing was in the range of 100-300 μm (examples 6, 11, 12), the prepared battery cell had better quick charge performance and cycle performance.

The anode electrode plate film layer of example 6 includes a first anode material layer and a second anode material layer, and compared with the single-layer anode material layer of example 15, the prepared battery cell has better quick charge performance and cycle performance.

The present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same constitution and exhibiting the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Further, various modifications that can be made to the embodiments and other modes of combining some of the constituent elements in the embodiments, which are conceivable to those skilled in the art, are also included in the scope of the present application within the scope not departing from the gist of the present application.

Claims

1. A negative electrode tab, comprising:

a negative electrode current collector;

and the membrane layer is arranged on at least one surface of the negative electrode current collector, and comprises pores, wherein the pore diameter of the pores on the upper surface of the membrane layer is larger than the pore diameter of the pores on the lower surface of the membrane layer.

2. The negative electrode tab of claim 1, wherein,

the pore diameter D2 of the film layer at a position 3/4 of the film layer thickness from the surface of the negative electrode current collector is larger than the pore diameter D1 of the film layer at a position 1/4 of the film layer thickness from the surface of the negative electrode current collector.

3. The negative electrode tab of claim 2, wherein,

the ratio of D2 to D1 is 1.2:1-3.5:1, alternatively 1.5:1-3.0:1.

4. the negative electrode tab of claim 2 or 3, wherein,

the D2 is 48-140 μm, optionally 60-120 μm.

5. The negative electrode tab of claim 2 or 3, wherein,

the D1 is 5-60 μm, optionally 30-60 μm.

6. The negative electrode sheet according to any one of claims 1 to 5, wherein,

the spacing between adjacent pores on the upper surface of the film layer is 100-300 mu m.

7. The negative electrode sheet according to any one of claims 1 to 6, wherein,

the thickness M0 of the film layer is 50-280 μm, optionally 80-180 μm.

8. The negative electrode sheet according to any one of claims 1 to 7, characterized in that,

the pore is in an inverted cone shape or an inverted truncated cone shape.

9. The negative electrode sheet according to any one of claims 1 to 8, wherein,

the membrane layer comprises a first negative electrode material layer arranged on at least one surface of the negative electrode current collector and a second negative electrode material layer arranged on the surface of the first negative electrode material layer.

10. The negative electrode sheet according to any one of claims 1 to 9, characterized in that,

the film layer includes a negative active material including at least one of soft carbon, hard carbon, graphite, silicon, a silicon oxygen compound, a silicon carbon composite, and a metal capable of forming an alloy with lithium.

11. A battery cell comprising a negative electrode sheet according to any one of claims 1-10.

12. A battery comprising the battery cell of claim 11.

13. An electrical device comprising a battery cell according to claim 11 or a battery according to claim 12.