CN215266366U

CN215266366U - Lithium ion battery pole piece and lithium ion battery

Info

Publication number: CN215266366U
Application number: CN202120562820.5U
Authority: CN
Inventors: 刘超; 吴志亮; 贺梦江; 张耀
Original assignee: Sunwoda Electric Vehicle Battery Co Ltd
Current assignee: Xinwangda Power Technology Co ltd
Priority date: 2021-03-18
Filing date: 2021-03-18
Publication date: 2021-12-21
Anticipated expiration: 2031-03-18

Abstract

The application discloses lithium ion battery pole piece and lithium ion battery. The lithium ion battery pole piece comprises a base material, an active material layer and an adhesive layer, wherein the active material layer is arranged on the surface of the base material and arranged along the length direction of the base material. The glue layer is arranged on the base material and arranged along the length direction of the base material, and the glue layer is positioned on at least one side of the active material layer. Because the adhesive layer is arranged on at least one side of the active material layer of the lithium ion battery pole piece, the adhesive layer can effectively improve the free energy of the surface of the base material, so that the expansion of cracks can be effectively blocked, and the risk that the base material is fractured due to the crack expansion when the lithium ion battery pole piece is rolled and flattened is reduced, thereby providing effective process guarantee for preparing the pole piece by adopting a thinner base material as a current collector.

Description

Lithium ion battery pole piece and lithium ion battery

Technical Field

The application relates to the technical field of lithium ion batteries, in particular to a lithium ion battery pole piece and a lithium ion battery.

Background

In the related art, when a lithium ion battery pole piece is manufactured, an aluminum foil is generally used as a substrate for a positive pole piece, and a copper foil is generally used as a substrate for a negative pole piece. The base material is provided with a coating area for coating anode or cathode slurry and a hollow foil area positioned on at least one side edge of the base material, the hollow foil area is used for forming a tab in the subsequent process, after the slurry coating is finished, the obtained lithium ion battery pole piece is required to be subjected to rolling treatment to enhance the bonding strength of the active material layer and the base material so as to prevent the active material layer from being peeled off in the processes of electrolyte soaking and subsequent use, and meanwhile, flattening treatment is required to eliminate the wrinkle phenomenon of the hollow foil area in the rolling process. As the demand for energy density of lithium ion batteries is increasing, more manufacturers have started to use a substrate with a small thickness, for example, a substrate with a thickness of 10 μm or less, as one of effective measures, however, if the substrate is too thin, the risk of fracture of the substrate due to crack propagation is high when the lithium ion battery pole piece is rolled and flattened.

SUMMERY OF THE UTILITY MODEL

The present application is directed to solving at least one of the problems in the prior art. Therefore, the application provides a lithium ion battery pole piece, which has lower risk of substrate fracture.

The application also provides a lithium ion battery with the lithium ion battery pole piece.

According to this application first aspect embodiment's lithium ion battery pole piece includes: a substrate; an active material layer disposed on a surface of the substrate along a length direction of the substrate; the glue layer is arranged on the substrate along the length direction of the substrate, and the glue layer is positioned on at least one side of the active material layer.

The lithium ion battery pole piece according to the embodiment of the application at least has the following technical effects: because the adhesive layer is arranged on at least one side of the active material layer of the lithium ion battery pole piece, the adhesive layer can effectively improve the free energy of the surface of the base material, so that the expansion of cracks can be effectively blocked, and the risk that the base material is fractured due to the crack expansion when the lithium ion battery pole piece is rolled and flattened is reduced, thereby providing effective process guarantee for preparing the pole piece by adopting a thinner base material as a current collector.

In addition, the lithium ion battery pole piece according to the embodiment of the application also has the following additional technical characteristics:

according to some of the embodiments of the present application, the glue layer abuts the active material layer in a width direction of the substrate.

According to some of the embodiments of the present application, the adhesive layer partially overlaps with the active material layer in a width direction of the substrate, and a width of an overlapping portion between the adhesive layer and the active material layer is 3mm or less.

Some of the embodiments according to the present application further include a mixed layer between the glue layer and the active material layer.

According to some of the embodiments of the present application, the adhesive layer further includes a primer layer, the primer layer being located between the substrate and the active material layer, and the primer layer being integrally formed with the adhesive layer.

According to some of the embodiments of the present application, the adhesive layer has a thickness of 1 μm to 100 μm.

According to some of the embodiments of the present application, the size layer is a long fiber based size layer.

According to some of the embodiments of the present application, the elongation of the glue layer is greater than or equal to 0.5%.

According to some of the embodiments of the present application, the bondline and the substrate have equal elongation.

According to the lithium ion battery of the embodiment of the second aspect of the present application, the lithium ion battery includes the lithium ion battery pole piece described in the embodiment of the first aspect.

The lithium ion battery according to the embodiment of the application has at least the following technical effects: because the adhesive layer is arranged on at least one side of the active material layer of the lithium ion battery pole piece of the lithium ion battery, the adhesive layer can effectively improve the free energy of the surface of the base material, so that the expansion of cracks can be effectively blocked, and the risk that the base material is fractured due to the expansion of the cracks when the lithium ion battery pole piece is rolled and flattened is reduced, thereby providing effective process guarantee for preparing the pole piece by adopting a thinner base material as a current collector.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

The above and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of a lithium ion battery pole piece according to an embodiment of the present application along a length direction;

FIG. 2 is a schematic cross-sectional structure diagram of the lithium ion battery pole piece in FIG. 1;

FIG. 3 is a schematic cross-sectional view of a lithium ion battery electrode piece according to yet another embodiment of the present disclosure;

FIG. 4 is a schematic cross-sectional structure diagram of a lithium ion battery pole piece according to yet another embodiment of the present application;

FIG. 5 is an exploded view of the structure of a cross-section of a lithium ion battery pole piece of yet another embodiment of the present application;

FIG. 6 is a schematic cross-sectional structure of an anilox roller used in coating a subbing layer on the lithium ion battery pole piece in FIG. 4;

FIG. 7 is a flow chart of a method of making a lithium ion battery pole piece according to one embodiment of the present application;

fig. 8 is a schematic process diagram of attaching a PP adhesive in the method for manufacturing a lithium ion battery electrode plate according to an embodiment of the present application;

fig. 9 is a schematic view of a process for attaching PP glue in a method for manufacturing a lithium ion battery electrode plate according to yet another embodiment of the present application.

Detailed Description

The conception and the resulting technical effects of the present application will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all embodiments, and other embodiments obtained by those skilled in the art without inventive efforts based on the embodiments of the present application belong to the protection scope of the present application.

In the description of the embodiments of the present application, if an orientation description is referred to, for example, the directions or positional relationships indicated by "upper", "lower", "left", "right", etc. are based on the directions or positional relationships shown in the drawings, it is only for convenience of description and simplification of description, and it is not intended to indicate or imply that the referred device or element must have a specific orientation, be configured and operated in a specific orientation, and thus, should not be interpreted as limiting the present application.

In the description of the embodiments of the present application, if a feature is referred to as being "disposed", "connected", or "mounted" to another feature, it can be directly disposed, fixed, or connected to the other feature or indirectly disposed, fixed, or connected to the other feature.

It should be understood that the thin substrate is one of the effective means for increasing the energy density of the lithium ion battery, wherein, taking the aluminum foil as the substrate of the positive electrode plate as an example, after the thickness of the aluminum foil is reduced from 12 μm to 10 μm, the energy density of the battery can be increased by more than 2%, and therefore, more manufacturers start to adopt the substrate with a thinner thickness. When the lithium ion battery pole piece prepared based on the thin substrate is subjected to the effects of flattening tension, traction tension and the like in the processes of rolling and flattening, the substrate is subjected to flattening tension, traction tension and the like in the processes of rolling and tape-feeding, the risk of fracture of the substrate due to crack propagation is high, the cracks can be defects of the substrate or cracks can be generated in the empty foil area due to rolling process wrinkles, and particularly, the possibility of cracking of the substrate at the edge position of the empty foil area or the junction position of the empty foil area and the coating area is highest in the rolling or flattening process.

Although the above-mentioned fracture problem can be solved to a certain extent by a process of multiple stretching and heating for a substrate with a thickness of 10 μm or less in order to ensure a good process yield and a throughput, it is necessary to develop equipment for the multiple stretching process, which has a complicated structure and a large occupied space, and requires precise temperature control, thus causing great difficulties in engineering practice.

Therefore, the embodiment of the application provides a solution, and the preparation method of the lithium battery positive pole piece or negative pole piece is improved, specifically, the surface free energy of the base material is improved in a mode of forming an adhesive layer on an aluminum foil or copper foil base material, so that cracks existing in the base material are not easy to expand, and therefore the base material is not easy to break in the process, and effective process guarantee is provided for preparing the pole piece by using a thin base material as a current collector.

Meanwhile, the glue layer can block the migration of lithium ions and has strong puncture resistance, so that the scheme of coating ceramic glue on the edge of the base material can be replaced by forming the glue layer at a proper position, and the safety of the battery is improved.

Referring to fig. 1, and fig. 2 to 5, the longitudinal direction of the base material 101 is the front-back direction in fig. 1, and the width direction of the base material 101 is the left-right direction in fig. 2. The lithium ion battery pole piece 100 according to the embodiment of the application comprises a substrate 101, an active material layer 103 and a glue layer 102. The active material layer 103 is disposed on the surface of the substrate 101 along the length direction of the substrate 101, the glue layer 102 is disposed on the substrate 101 along the length direction of the substrate 101, and the glue layer 102 is located on at least one side of the active material layer 103.

Therefore, the glue layer 102 is formed on at least one side of the active material layer 103, and the glue layer 102 can effectively improve the free energy of the surface of the base material 101, so that the expansion of cracks can be effectively blocked, the risk of breakage of the base material 101 in the process is reduced, and effective process guarantee can be provided for preparing the pole piece by using the thin base material 101 as a current collector.

Specifically, as shown in fig. 3, the base material 101 has a coating area 201 at a middle position on one surface thereof in a length direction and empty foil areas 202 at both sides of the coating area 201, and the empty foil areas 202 at both sides may be cut out of the tab by a die cutting process later. The active material layer 103 is formed of a positive electrode material slurry or a negative electrode material slurry, and is disposed in the coating region 201. The glue layers 102 have two, wherein one glue layer 102 is at least partially located in the left empty foil area 202, and the other glue layer 102 is at least partially located in the right empty foil area 202, so as to reduce the risk of the substrate 101 breaking in the left and right empty foil area 202 areas.

It is understood that the substrate 101 may be an aluminum foil as a current collector of the positive electrode tab, or a copper foil as a current collector of the negative electrode tab.

It is understood that the active material layer 103 is a functional layer formed by coating the positive electrode material slurry or the negative electrode material slurry on the coating region 201 of the substrate 101. The anode material slurry or the cathode material slurry is prepared from different active materials, conductive agents and binders according to different formulas.

It is understood that the active material layer 103 may be formed by a single-sided continuous coating, a double-sided continuous coating, or a single-sided intermittent coating or a double-sided intermittent coating, which is not described herein again.

It can be understood that the substrate 101 has a high possibility of cracking at the boundary position of the empty foil area 202 and the coating area 201, and therefore, in order to ensure that the gel layer 102 can prevent cracks and crack propagation at the boundary position, in some embodiments, in the width direction of the substrate 101, the gel layer 102 abuts against the active material layer 103, and therefore, the gel layer 102 and the active material layer 103 can completely cover the boundary position of the empty foil area 202 and the coating area 201 on the side surface of the active material layer 103, and meanwhile, since only abutting contact is provided between the gel layer 102 and the active material layer 103, the gel layer 102 does not have an adverse effect on the active material layer 103, so that the lithium battery pole piece 100 in this embodiment can prevent cracks and crack propagation of the substrate 101, and at the same time, the gel layer 102 does not have an adverse effect on the active material layer 103.

Referring to fig. 2, in order to prevent the substrate 101 from being cracked by rolling, flattening, and running as much as possible while ensuring that the active material layer 103 is not excessively affected, in some embodiments, the glue layer 102 and the active material layer 103 are partially overlapped in the width direction of the substrate 101, and the width of the overlapped portion between the glue layer 102 and the active material layer 103 is 3mm or less. At least part of the glue layer 102 is disposed in the empty foil region 202, and extends from one end of the empty foil region 202 away from the active material layer 103 in the width direction of the substrate 101 to above or below the active material layer 103 to partially overlap with the active material layer 103. The width of the overlapping portion of the glue layer 102 and the active material layer 103 is 3mm or less.

Therefore, firstly, one side edge of the glue layer 102 covers the first edge 203 of the empty foil area 202, so that the crack existing due to the material defect does not expand to cause the substrate to break, and the possibility of the crack occurring at the edge of the lithium ion battery pole piece 100 in the process of passing through a roller or being pulled is greatly reduced. Next, the glue layer 102 extends from the first edge 203 to cover the second edge 204 at the boundary between the empty foil area 202 and the coating area 201, so that the second edge 204 is not prone to generate cracks and propagation of cracks to cause fracture of the substrate 101 due to the glue layer 102 during the process of rolling or pulling the lithium ion battery electrode sheet 100, for example, during the processes of rolling, flattening, and the like. Meanwhile, the adhesive layer 102 can prevent the lithium ion battery pole piece 100 from appearance problems. It is conceivable that since the width of the overlapping portion between the glue layer 102 and the active material layer 103 is 3mm or less, too much influence is not exerted on the active material layer 103.

It should be understood that the width of the overlapping portion between here and the active material layer 103 is below 3mm, including both the case where the glue layer 102 is located at the bottom of the active material layer 103 and the case where the glue layer 102 is located at the top of the active material layer 103. In the case where the gel layer 102 is located at the bottom of the active material layer 103, a conductive agent may be added to the gel layer to enable the overlapping portion of the gel layer 102 and the active material layer 103 to conduct electricity.

Of course, it is understood that the adhesive layer 102 may not cover the entire empty foil area 202, in which case, if there is a crack in the lithium ion battery electrode sheet 100, the crack is blocked after propagating to the area covered by the adhesive layer 102, so as to avoid the substrate 101 from being broken.

To further reduce the likelihood of the substrate 101 cracking or crack propagation at the location of the second edge 204 where the empty foil region 202 interfaces with the coating region 201, in some embodiments, the lithium ion battery electrode sheet 100 further includes a hybrid layer 120, the hybrid layer 120 being located between the subbing layer 102 and the active material layer 103. Specifically, the gel layer 102 is mixed with the active material layer 103 at the intersection to form the mixed layer 120, and the composition of the mixed layer 120 includes the gel layer 102 and the active material layer 103. Therefore, the lithium ion battery pole pieces 100 are bonded on the surface of the base material 101 together, and when the lithium ion battery pole pieces 100 are subjected to the rolling and belt traction forces, the lithium ion battery pole pieces 100 are only abutted against the lithium ion battery pole pieces 100 in contact with the active material layer 103 relative to the adhesive layer 102, and the lithium ion battery pole pieces 100 in the embodiment can avoid the separation of the contact parts of the adhesive layer 102 and the active material layer 103, so that the stress of the base material 101 at each position is uniform, and the possibility of substrate cracking is reduced.

It is understood that the glue layer 102 may be formed in a coating manner. For example, the glue layer 102 may be formed by coating the empty foil area 202 by gravure coating, double coating, or spraying. Thereby, it is also facilitated to achieve intermixing of the glue layer 102 and the active material layer 103 at the interface.

The glue can be quick-drying glue, hot melt glue and other common glue solutions, and various binders commonly used in the lithium ion battery coating process, such as water-based acrylate, styrene butadiene rubber, polyvinylidene fluoride, acrylonitrile, polyvinyl alcohol, polytetrafluoroethylene, polyethylene oxide and the like, and can be a single binder or a mixture of several binders, such as styrene butadiene rubber and acrylic acid, wherein the acrylic acid has strong binding property with a base material, and the styrene butadiene rubber enables the glue layer to have excellent flexibility and not to be easily broken.

In addition, the formation of the adhesive layer 102 by coating can be performed before, after or simultaneously with one of the processes of the preparation of the lithium ion battery electrode sheet 100, for example, the adhesive layer 102 is coated in advance before the coating of the active material layer 103, or the adhesive layer 102 is formed by coating simultaneously with the active material layer 103, or the adhesive layer 102 can be coated before rolling or before flattening. It is understood that the adhesive layer 102 is formed by coating in different processes, and the adhesive layer 102 can reduce the possibility of cracks or crack propagation in the lithium ion battery pole piece 100 in subsequent processes.

Referring to fig. 3, it can be appreciated that, in some embodiments, the paste coating is simultaneously performed on the empty foil region 202 of the substrate 101 while the cathode material or anode material slurry is coated, and thus, the paste layer 102 and the active material layer 103 may be simultaneously formed. Therefore, the glue layer 102 is coated on the empty foil area 202, and the ceramic coating can be replaced, so that the obtained lithium ion battery pole piece can prevent crack propagation, and meanwhile, migration of lithium ions can be hindered, and the safety of the battery can be improved.

Referring to fig. 4, it can be understood that the lithium ion battery pole piece 100 further includes an undercoat layer 104, the undercoat layer 104 being located between the substrate 101 and the active material layer 103, and the undercoat layer 104 being integrally formed with the adhesive layer 102. For example, in the preparation of an electrode sheet of, for example, an LFP system, the primer layer 104 containing a conductive agent may be formed on the substrate 101, and the active material layer 103 may be formed on the outer surface of the primer layer 104, so that, in order to save the process, in some embodiments, the primer layer 104 may be applied and the glue layer 102 may be simultaneously formed on the empty foil region 202, and thus, since the glue layer 102 and the primer layer 104 are integrally formed, the glue layer 102 may completely cover the boundary region between the empty foil region 202 and the coating region 201, so that the possibility of the substrate 101 breaking at this position is greatly reduced.

In some embodiments, in the manner described above, the thickness of the glue layer 102 formed in the empty foil region 202 is greater than the thickness of the primer layer 104 formed in the coating region 201. Therefore, the primer layer 104 located in the coating region 201 is thin, and does not affect the ultimate compaction of the positive electrode, and the glue layer 102 located in the blank foil region 202 has a certain thickness, so that the effect of preventing the crack propagation of the substrate 101 can be effectively achieved. It is easy to understand that the gluing mode is more suitable for the wide pole ear pole piece with thicker thickness.

It is understood that the priming in the above manner can be achieved by using a stepped anilox roller 200, and specifically, as shown in fig. 6, the stepped anilox roller 200 has a mesh depth a corresponding to the empty foil area 202 of the substrate 101 and a mesh depth B corresponding to the coating area 201 of the substrate 101, and the depth a and the depth B are not equal in size.

It is understood that in order to prevent the formed adhesive layer 102 from sticking to the roll, in some embodiments, the surface of the adhesive layer 102 is further treated with silicone oil, or coated with a PP layer.

It is further understood that the thicker the thickness of the glue layer 102 is, the better the effect of improving the fracture of the substrate 101, but the overall thickness and cost of the lithium ion battery pole piece 100 should be considered at the same time. In some embodiments, the thickness of the adhesive layer 102 is between 1 μm and 100 μm, and when the thickness of the adhesive layer 102 is 60 μm, the adhesive layer 102 can keep the overall thickness and cost of the lithium ion battery pole piece 100 low, and improve the easy fracture of the substrate 101.

In some embodiments, the bondline 102 comprises one or more of the following adhesives: water-based acrylate, water-based acrylic acid, styrene-butadiene rubber, polyvinylidene fluoride, acrylonitrile, polyvinyl alcohol, polytetrafluoroethylene and polyethylene oxide. It will be appreciated that in order to enhance the crack stop effect of the bondline 102 coated with these adhesives.

In some embodiments, the bondline 102 is a long fiber-based bondline. The long fiber-based glue layer is a glue layer containing a long fiber composite material, so that the glue layer 102 has the characteristics of high toughness and high strength, and the crack arrest effect is better. The long fiber composite material can be any one or combination of a plurality of carbon fibers, glass fibers, attapulgite and the like.

It is also understood that the glue layer 102 may be formed in a taping manner. Specifically, the adhesive layer 102 is formed by attaching an adhesive tape to the empty foil area 202. The adhesive tape can be termination adhesive, tab adhesive, insulating adhesive or the like, and can also be adhesive tapes commonly used by lithium ion batteries, such as blue adhesive, green adhesive, transparent adhesive and the like. The adhesive tapes have stable electrochemical performance and almost have no influence on the lithium ion battery. As before, the formation of the adhesive layer 102 by taping can be performed before, after, or simultaneously with one of the processes of the preparation of the lithium ion battery electrode sheet 100, for example, taping the empty foil region 202 in advance before the coating of the active material layer 103, or taping the empty foil region 202 before rolling or flattening. It is understood that if the adhesive layer 102 is formed by taping in different processes, the adhesive layer 102 can reduce the possibility of cracks or crack propagation in the lithium ion battery pole piece 100 in subsequent processes.

It can be understood that the base 101 has a certain ductility, and therefore, in order to have a good crack-stopping effect, in some embodiments, the elongation of the adhesive layer 102 is greater than or equal to 0.5%, and thus, the adhesive layer 102 can have a certain plastic deformation capability, and the adhesive layer 102 can be prevented from being stretched together with the base 101 when the lithium ion battery pole piece 100 is rolled, flattened, and the like, so that the adhesive layer 102 is prevented from falling off the base 101 due to the stretching of the base 101 and the non-stretching of the adhesive layer 102.

In some embodiments, the elongation of the bondline 102 is consistent with the elongation of the substrate 101, and the bondline 102 may be stretched simultaneously with the substrate 101. Therefore, when the lithium ion battery pole piece 100 is rolled and flattened, the adhesive layer 102 has the ability of effectively preventing cracks from generating or expanding because the elongation of the adhesive layer 102 is consistent with that of the base material 101.

According to the lithium ion battery in the second aspect of the present application, the lithium ion battery includes the lithium ion battery pole piece in the first aspect of the present application. Because the adhesive layer is arranged on at least one side of the active material layer of the lithium ion battery pole piece of the lithium ion battery, the adhesive layer can effectively improve the free energy of the surface of the base material, so that the expansion of cracks can be effectively blocked, and the risk that the base material is fractured due to the expansion of the cracks when the lithium ion battery pole piece is rolled and flattened is reduced, thereby providing effective process guarantee for preparing the pole piece by adopting a thinner base material as a current collector.

The following describes a method for manufacturing a lithium ion battery pole piece according to an embodiment of the present application with reference to fig. 7 to 9.

Referring to fig. 7, the method for manufacturing a lithium ion battery pole piece according to the embodiment of the present application includes the following steps:

s10: preparing a substrate, positive electrode material slurry or negative electrode material slurry, wherein the substrate is provided with two opposite surfaces, and at least one surface is provided with a coating area and a hollow foil area positioned on at least one side of the coating area along the length direction;

s20: coating the positive electrode material slurry or the negative electrode material slurry on a coating area to form an active material layer, so as to obtain a lithium ion battery pole piece;

s30: and forming a glue layer in the empty foil area.

Therefore, the adhesive layer is formed in the empty foil area, and the adhesive layer can effectively improve the free energy of the surface of the base material, so that the lithium ion battery pole piece obtained by the method is not easy to break when being rolled and flattened subsequently, and has the characteristic of high yield.

It is understood that, in step S10, the substrate may be an aluminum foil as the positive electrode sheet current collector or a copper foil as the negative electrode sheet current collector, and generally, the substrate is usually supplied in a roll form, and the processes are completed by unwinding and tape-feeding. Further, it is easily understood that the substrate has a coating region for coating the positive electrode material slurry or the negative electrode material slurry in the length direction thereof, and on both sides of the coating region, there are also left empty foil regions which can cut out tabs in a subsequent process.

It is understood that the positive electrode material slurry or the negative electrode material slurry is prepared according to a suitable formulation. For example, taking a positive electrode material slurry as an example, for different systems, such as an LFP system, an NCM system, and the like, a corresponding active material is prepared and stirred together with a conductive agent, a binder, and the like to obtain a positive electrode slurry. Of course, the anode material slurry can also be prepared according to a known manner, and will not be described in detail herein.

It is to be understood that the slurry coating may be performed in various known manners, such as knife coating, roll transfer coating, and extrusion coating, in step S20. The form of the active material layer may be a single-side continuous coating, a double-side continuous coating, a single-side intermittent coating, or a double-side intermittent coating, which is not described herein again. It is conceivable that, in general, after the active material layer is formed by coating, the active material layer needs to be dried, and therefore, in step S30, a drying step is usually further provided to form a lithium ion battery electrode sheet.

It can be understood that after the lithium ion battery pole piece is prepared, a rolling treatment is also needed to enhance the bonding strength of the active material layer and the substrate so as to prevent the active material layer from peeling off during electrolyte soaking and subsequent use. Meanwhile, through rolling, the porosity among the active substances, the conductive agent and the binding agent in the active material layer can be reduced, so that the volume of the battery cell can be compressed, the energy density of the battery cell can be improved, the resistance of the battery can be reduced, and the performance of the lithium ion battery can be improved.

It can be understood that, in the process of rolling the lithium ion battery pole piece, the hollow foil area of the lithium ion battery pole piece can be wrinkled, so that after the rolling process, the method further comprises the step of flattening, wherein the lithium ion battery pole piece is flattened, so that the base material is stretched and extended in the hollow foil area to eliminate wrinkles.

It can be understood that after the lithium ion battery pole piece is flattened, subsequent processes such as die cutting, slitting and winding are performed, and are not described in detail herein.

It is understood that the glue layer may be formed by coating or taping.

Example 1:

before the coating area 201 of the substrate 101 is coated with the positive electrode material or the negative electrode material slurry, polyvinylidene fluoride is sprayed on the empty foil area 202 as a binder, and drying treatment is performed. Wherein the glue layer 102 enters the coating area 201 for 2mm, the thickness of the glue layer 102 is 15 μm, and then the coating area 201 is coated with slurry of positive electrode material or negative electrode material to form the active material layer 103, and the thickness of the active material layer 103 is 200 μm.

Example 2:

before the coating area 201 of the substrate 101 is coated with the positive electrode material or the negative electrode material slurry, acrylic is coated on the empty foil area 202 in a gravure primer coating manner as a binder, and drying treatment is performed. Wherein the glue layer 102 enters the coating area 201 for 3mm, the thickness of the glue layer 102 is 60 μm, and then the coating area 201 is coated with slurry of positive electrode material or negative electrode material to form the active material layer 103, and the thickness of the active material layer 103 is 250 μm.

Example 3:

the lithium ion battery pole piece 100 is an LFP system positive pole piece, before the coating area 201 of the substrate 101 is coated with slurry, styrene-butadiene rubber and acrylic acid are mixed with a conductive agent SP by adopting a step-shaped anilox roller, and the whole coating is carried out in a gravure priming manner, so that a priming layer 104 is formed in the coating area 201, the thickness of an active material layer 103 is 150 μm, and a glue layer 102 is formed in an empty foil area 202, wherein the thickness of the priming layer 104 is 10 μm, and the thickness of the glue layer 102 is 50 μm.

Example 4:

while coating the positive electrode material or negative electrode material slurry in the coating area 201 of the substrate 101, simultaneously coating the adhesive in the empty foil area 202 by using a conventional die head with oily PVDF as a binder, wherein the thickness of the adhesive layer 102 and the thickness of the active material layer 103 are both 100 μm.

Example 5:

after the coating of the positive electrode material or negative electrode material slurry was completed, the coating was performed with styrene-butadiene rubber and acrylic acid in the empty foil region 202, the gel layer 102 was not coated on the active material layer 103, the thickness of the active material layer 103 was 200 μm, and the thickness of the gel layer 102 was 70 μm.

Example 6:

after the coating of the positive electrode material or the negative electrode material slurry is completed, referring to fig. 8 and 9, the lithium ion battery pole piece continues to be transported along the X direction, and the tape sticking mechanism 105 is arranged in the direction to stick the tape on the empty foil area 202, so as to form the glue layer 102. The tape sticking mechanism 105 includes a tape unwinding mechanism 106, a deviation correcting mechanism 107, a heating press roller 108, a back roller 109, and a CCD. The tape unwinding mechanism 106 includes a PP glue placing roller 110 and a tension roller 111. The unwinding speed of the adhesive tape unwinding mechanism 106 is matched with the tape running speed of the lithium ion battery pole piece, the distance between the CCD detection adhesive layer 102 and the edge of the empty foil area 202 is fed back to an automatic control system of the device, and the deviation rectifying mechanism 107 rectifies the deviation through a feedback signal of the CCD to ensure that the edge distances are consistent. The gap between the heated pressing roller 108 and the back roller 109 is adjusted to melt and thin the PP glue, and finally the PP glue is stuck to the empty foil area 202. The thickness of the rubberized adhesive layer 102 can be controlled by adjusting the cylinder pressure of the heating press roller 108 and the gap between the back roller 109. The heating mode is mainly electric heating. It is understood that in the embodiment 6, the rubberizing mechanism 105 may be disposed at a position between the nip roller 112 and the nip roller 113, or may be disposed before the nip roller 112.

The lithium ion battery pole piece 100 prepared in the above example is verified in the rolling process, and the results are shown in table 1.

Table 1: roll-in strip breakage data:

referring to table 1, by disposing the adhesive layer 102 on the empty foil area 202 of the substrate of the lithium ion battery electrode sheet 100, the fracture phenomenon of the substrate 101 can be greatly improved.

In the description herein, references to the description of "some embodiments" mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the application, the scope of which is defined by the claims and their equivalents.

Claims

1. Lithium ion battery pole piece, its characterized in that includes:

a substrate;

an active material layer disposed on a surface of the substrate along a length direction of the substrate;

the glue layer is arranged on the substrate along the length direction of the substrate, and the glue layer is positioned on at least one side of the active material layer.

2. The lithium ion battery pole piece of claim 1, wherein the glue layer abuts the active material layer in a width direction of the substrate.

3. The lithium ion battery electrode sheet according to claim 1, wherein the adhesive layer partially overlaps with the active material layer in a width direction of the substrate, and a width of an overlapping portion between the adhesive layer and the active material layer is 3mm or less.

4. The lithium ion battery pole piece of claim 1, further comprising a mixed layer between the glue layer and the active material layer.

5. The lithium ion battery pole piece of claim 1, further comprising an undercoat layer, wherein the undercoat layer is located between the substrate and the active material layer, and wherein the undercoat layer is integrally formed with the adhesive layer.

6. The lithium ion battery pole piece of claim 1, wherein the adhesive layer has a thickness of 1 μm to 100 μm.

7. The lithium ion battery pole piece of claim 6, wherein the glue layer is a long fiber based glue layer.

8. The lithium ion battery pole piece of claim 1, wherein the elongation of the glue layer is greater than or equal to 0.5%.

9. The lithium ion battery pole piece of claim 1, wherein the adhesive layer has an elongation equal to that of the substrate.

10. A lithium ion battery, comprising: the lithium ion battery pole piece of any one of claims 1 to 9.