WO2023142661A1 - Winding device and winding method - Google Patents

Abstract

The present application relates to the technical field of battery manufacturing, and relates to a winding device and a winding method. The present application provides a winding device, comprising: a winding component for winding a first separator, a negative electrode plate, a second separator, a positive electrode plate, and a third separator; and a traction mechanism configured to pull a roll-in end of the third separator to the winding component before a roll-in end of the positive electrode plate enters the winding component, such that the roll-in end of the third separator enters the winding component earlier than the roll-in end of the positive electrode plate. The present application further provides a winding method. The winding device and the winding method are used for performing winding forming on a high-safety electrode assembly, can implement industrial production of the electrode assembly, and improve the manufacturing efficiency of the electrode assembly.

Description

Winding equipment and winding method

Cross References to Related Applications

This application claims priority to the Chinese patent application (202210109134.1) filed on January 28, 2022, entitled "Winding Equipment and Winding Method", the entire content of which is incorporated herein by reference.

technical field

The present application relates to the technical field of battery manufacturing, in particular, to a winding device and a winding method.

Background technique

With the rapid development of the new energy vehicle industry, the technical level of power batteries is becoming more and more mature, and the safety performance of power batteries has become one of the important indicators to measure its performance. The wound electrode assembly is an important part inside the battery cell, and the safety performance of the electrode assembly plays a decisive role in the safety performance of the battery cell. However, even if the structure of the electrode assembly is improved to improve the safety performance of the battery cell, there is currently no corresponding winding equipment, resulting in the impossibility of industrial production even after the structure of the electrode assembly is improved.

Contents of the invention

For this reason, the present application proposes a winding device and a winding method for winding and forming an electrode assembly with high safety performance, which can realize the industrial production of the electrode assembly and improve the manufacturing efficiency of the electrode assembly.

Some embodiments of the present application propose a winding device for winding and forming an electrode assembly. The electrode assembly includes a first separator, a negative electrode sheet, a second separator, a positive electrode sheet, and a third layer stacked in sequence. The separation film, the length of the third separation film is shorter than that of the first separation film and the second separation film, and the winding device includes: a winding part for winding the first separation film, the Negative electrode sheet, the second separator, the positive electrode sheet and the third separator; a traction mechanism configured to draw the positive electrode sheet before the roll-in end of the positive electrode sheet enters the winding part The winding end of the third separator is pulled to the winding part, so that the winding end of the third separator enters the winding part before the winding end of the positive pole piece.

The winding device of some embodiments of the present application includes a pulling mechanism, which can pull the winding end of the third separator to the winding part before the winding end of the positive pole piece enters the winding part, so that the third separator The roll-in end of the film enters the winding part before the roll-in end of the positive electrode sheet, and the third separator and the second separator are stacked between the innermost ring of the positive electrode sheet and the negative electrode sheet inside it. When the lithium precipitation phenomenon occurs, the lithium dendrites are not easy to pierce the separator, resulting in the contact between the negative pole piece and the positive pole piece, thereby causing an internal short circuit of the electrode assembly. The electrode assembly wound and formed by using the winding device has high safety performance, and the winding device can realize the industrial production of the electrode assembly and improve the manufacturing efficiency of the electrode assembly.

According to some embodiments of the present application, the winding device further includes: a glue application mechanism configured to apply a glue layer to the winding-in end of the third isolation film; wherein, the third isolation film and the The second separation film is adjacently arranged, and the pulling mechanism is configured to pull the roll-in end of the third separation film coated with the glue layer to the winding part, so that the third separation film The roll-in end and the second isolation film are bonded by the adhesive layer.

In the above scheme, first apply the glue layer to the roll-in end of the third separator through the glue-applying mechanism, then pull the roll-in end of the third separator to the winding part, and connect the roll-in end of the third separator to the winding part. The second separator is bonded by an adhesive layer, not only can the third separator be introduced into the winding part through the second separator, but also the position of the winding end of the third separator on the second separator can be fixed, ensuring that the electrode assembly After winding and forming, the winding-in end of the third separator exceeds the winding-in end of the positive pole piece.

According to some embodiments of the present application, the gluing mechanism is configured to switch between a working position and a non-working position, wherein: when the gluing mechanism is in the working position, the gluing mechanism is used to The roll-in end of the third isolation film is coated with the glue layer; when the glue application mechanism is in the non-working position, the roll-in end of the glue application mechanism away from the third isolation film is on the The path of movement under the traction of the traction mechanism.

In the above scheme, the gluing mechanism can move to the non-working position after applying the glue layer to the roll-in end of the third separator, so as to stay away from the moving path of the roll-in end of the third separator, so that the roll-in end of the third separator can The winding end moves smoothly to the winding part under the traction of the traction mechanism.

According to some embodiments of the present application, the winding device further includes: a support member disposed on a side of the second separator close to the negative electrode sheet; wherein the pulling mechanism is configured to pull the The roll-in end of the third isolation film and the second isolation film are pressed against the support member, so that the roll-in end of the third isolation film and the second isolation film are bonded by the adhesive layer.

In the above solution, after the pulling mechanism pulls the rolling-in end of the third separator to the winding part, the pulling mechanism presses the rolling-in end of the third separator and the second separator to the support member, so that the third separator The roll-in end of the film and the two sides of the second isolation film are pressed, and the roll-in end of the third isolation film and the second isolation film are reliably bonded through the adhesive layer.

According to some embodiments of the present application, the traction mechanism includes a driving member and a pick-up member, the drive member is used to drive the pick-up member to switch between the first position and the second position, when the pick-up member is in the At the first position, the pick-up member picks up the roll-in end of the third separator, and when the pick-up member is in the second position, the pick-up member picks up the roll-in end of the third separator and The second separator is pressed toward the support.

In the above solution, the driving member can automatically drive the pick-up member to switch between the first position and the second position, so as to realize the automatic execution of the action of pulling the roll-in end of the third separator to the winding part, thereby realizing the winding device The electrode assembly of this structure is automatically wound and formed.

According to some embodiments of the present application, the pick-up member includes a pair of clamping parts, and the pair of clamping parts are used to clamp the third isolation film.

In the above scheme, a pair of clamping parts are used to clamp the third separator to pull the roll-in end of the third separator to move, and the process of pulling the roll-in end of the third separator to move is stable and reliable, and the third separator The roll-in end of the film is not easily separated from the pick-up piece.

According to some embodiments of the present application, the pick-up member is rotatably mounted on the output end of the drive member so as to have different postures at the first position and the second position respectively.

In the above solution, since the pick-up member can be switched between two states by rotating, one state is used to clamp and pull the rolling end of the third separator to move, and the other state is used to clamp the third separator. The rolled-in end of the isolation film presses the rolled-in end of the third isolation film and the second isolation film against the support. The action of pulling the roll-in end of the third separator to move and the action of pressing the roll-in end of the third separator and the second separator to the support is completed by using a pick-up member, thereby reducing the number of parts of the winding device, The construction of the winding device is simplified.

According to some embodiments of the present application, the winding device further includes: a cutting mechanism for cutting the third separator.

In the above scheme, by setting the cutting mechanism, the third separator can be cut in time, so that the third separator can only be involved in the innermost circles of the electrode assembly, which not only overcomes the problem of lithium deposition in the inner ring of the electrode assembly. The problem of crystal piercing through the separator is improved to improve the safety performance of the electrode assembly, and it also saves the amount of the third separator and improves the energy density of the electrode assembly.

According to some embodiments of the present application, the winding device further includes: a roll for carrying the third separator.

In the above solution, by setting the reel to carry the third isolation film, the third isolation film is supplied in the form of roll material, which has a simple structure and is easy to implement.

Some embodiments of the present application propose a winding method for winding and forming an electrode assembly. The electrode assembly includes a first separator, a negative electrode sheet, a second separator, a positive electrode sheet, and a third layer stacked in sequence. The isolation film, the length of the third isolation film is smaller than the first isolation film and the second isolation film, and the winding method includes:

Before the roll-in end of the positive pole piece enters the roll-up part, the roll-in end of the third separator is drawn to the roll-up part, so that the roll-in end of the third separator is ahead of the roll-in end of the third separator. The winding end of the positive pole piece enters the winding part.

Using the winding method of the embodiment of the present application to wind and form the electrode assembly, the winding end of the third separator can enter the winding part before the winding end of the positive electrode sheet, and the third separator and the second separator are stacked. Between the innermost ring of the positive pole piece and the negative pole piece inside it. When the lithium precipitation phenomenon occurs, the lithium dendrites are not easy to pierce the separator, resulting in the contact between the negative pole piece and the positive pole piece, thereby causing an internal short circuit of the electrode assembly. The electrode assembly wound and formed by the winding method has high safety performance.

According to some embodiments of the present application, the third isolation film is disposed adjacent to the second isolation film, and the winding method further includes:

Paste or thermally fuse the roll-in end of the third isolation film to the second isolation film.

In the above solution, the winding end of the third separator and the second separator are connected by pasting or hot-melting, so that not only the third separator can be introduced into the winding part through the second separator, but also the third separator can be fixed. The position of the roll-in end of the film on the second separator ensures that the roll-in end of the third separator exceeds the roll-in end of the positive pole piece after the electrode assembly is wound and formed.

According to some embodiments of the present application, the winding method further includes:

After the third separator is wound at least one turn, the third separator is cut.

In the above solution, after the third separator is wound for at least one turn, two layers of separators are stacked between the innermost ring of the positive pole piece and the negative pole piece inside it, thereby avoiding the innermost circle of the positive pole piece. Lithium crystallization pierces the separator when lithium crystallization occurs on the inner side of the ring, which can significantly improve the safety performance of the electrode assembly, save the amount of the third separator, and increase the energy density of the electrode assembly.

Additional aspects and advantages of the 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 application.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings that are required in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

What Fig. 1 shows is the structural representation of the winding equipment of some embodiments of the present application;

Figure 2 shows a cross-sectional view of an electrode assembly wound and formed by a winding device according to some embodiments of the present application;

Figure 3 shows a schematic structural view of the gluing mechanism of the winding device in some embodiments of the present application in a working position;

FIG. 4 shows a schematic diagram of a state in which the gluing mechanism of the winding device of some embodiments of the present application is in a non-working position;

Fig. 5 shows a schematic diagram of the state of cooperation between the traction mechanism and the support in the winding device of some embodiments of the present application;

Fig. 6 shows a schematic diagram of the pick-up part of the traction mechanism of the winding device picking up the roll-in end of the third separator in some embodiments of the present application;

Fig. 7 is a schematic diagram showing the state of cutting the third separator by the cutting mechanism of the winding device according to some embodiments of the present application;

What Fig. 8 shows is the process flow chart of the winding method of some embodiments of the present application;

In the drawings, the drawings are not drawn to scale.

Marking description: 100-winding equipment; 110-winding parts; 111-winding needle; 120-traction mechanism; 121-pickup; 1211-clamping part; 150-cutting mechanism; 160-reel; 200-electrode assembly; 210-negative pole piece; 220-positive pole piece; 241-the first side; 242-the second side; 250-the third separation film; 251-the roll-in end of the third separation film; 252-the ending end of the third separation film.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the technical field of this application; the terms used in this application in the description of the application are only to describe specific implementations The purpose of the example is not intended to limit the present application; the terms "comprising" and "having" in the specification and claims of the present application and the description of the above drawings, as well as any variations thereof, are intended to cover non-exclusive inclusion. The terms "first" and "second" in the description and claims of the present application or the above drawings are used to distinguish different objects, rather than to describe a specific sequence or primary-subordinate relationship.

Reference in this application to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The occurrences of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is understood explicitly and implicitly by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

What needs to be explained in the description of this application is that the terms "installation", "connection", "connection" and "attachment" should be understood in a broad sense unless otherwise clearly specified and limited, for example, it can be a fixed connection or a Detachable connection, or integral connection; can be directly connected, can also be indirectly connected through an intermediary, and can be internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations.

"Plurality" in this application refers to two or more (including two).

The electrode assembly mentioned in the embodiments of the present application is an important part of a battery cell in a lithium-ion battery. The electrode assembly is formed by stacking and winding the positive pole piece, the negative pole piece and the separator, and the battery cell mainly relies on lithium ions to move between the positive pole piece and the negative pole piece to work. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode current collector. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode current collector. surface.

In the related technology, after the electrode assembly is wound and formed, there is an area difference between the positive pole piece and the negative pole piece in the bending area of the innermost circles of the electrode assembly within the same angle range, which is prone to lithium precipitation and lithium crystallization. It is easy to pierce the separator and cause the positive pole piece and the negative pole piece to be short-circuited, resulting in a short circuit inside the electrode assembly. At present, there is an improvement idea of the electrode assembly. At least one more layer of isolation film is provided between the positive pole piece and the negative pole piece of the innermost circle of the electrode assembly. Even if lithium precipitation occurs, lithium crystallization is not easy to pierce the isolation. Membrane, so as to overcome the above defects, so that the electrode assembly also has better safety performance when lithium precipitation occurs in the innermost ring. However, there is currently no corresponding winding equipment and winding method that can realize the industrial production of this kind of electrode assembly.

The inventor found through research that in the existing process of winding and forming the electrode assembly, the winding part rotates once and is respectively involved in the stacked first separator, negative pole piece, second separator and positive pole piece, wherein, The positive pole piece finally enters the winding unit. If another layer of separator is added after the first separator, the negative electrode sheet and the second separator are stacked and wound on the winding part and before the positive electrode sheet is wound on the winding part, the newly added separator After entering the winding part, it is located between the positive pole piece and the first separator of the inner ring, and it will be possible to have the first separator and the newly added isolation between the innermost positive pole piece and the negative pole piece inside it. Membrane, that is, two layers of isolation film, thus providing a new winding idea for winding and forming the above-mentioned electrode assembly, which can realize the industrial production of the above-mentioned electrode assembly, and reduce the improvement range and cost of the existing winding equipment.

Based on the above ideas, the inventors of the present application proposed a technical solution to introduce a new separator (i.e. the third separator described below) into the winding component before the roll-in end of the positive pole piece enters the winding component, so that The roll-in end of the new separator enters the winding part before the roll-in end of the positive pole piece, so that there are two layers of separator between the innermost ring of the positive pole piece and the negative pole piece inside it, using winding forming The electrode assembly has high safety performance, and can realize the industrial production of the electrode assembly, and improve the manufacturing efficiency of the electrode assembly.

FIG. 1 shows a schematic structural view of a winding device according to some embodiments of the present application; FIG. 2 shows a cross-sectional view of an electrode assembly wound and formed by the winding device according to some embodiments of the present application.

As shown in Figures 1 and 2, some embodiments of the present application propose a winding device 100 for winding and forming an electrode assembly 200. The winding device 100 includes a winding part 110 and four feeding mechanisms (in the figure not shown).

The applicable battery cells for the electrode assembly 200 described in the embodiments of this application may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries. Examples are not limited to this. However, for brevity of description, the following embodiments all take the winding process of the electrode assembly 200 in a lithium-ion battery as an example for illustration.

As shown in FIGS. 1 and 2 , the electrode assembly 200 includes a first separator 230 , a negative electrode sheet 210 , a second separator 240 , a positive electrode sheet 220 and a third separator 250 that are stacked and wound. The first separator 230 and the second separator 240 are rolled into the winding member 110 before the negative electrode sheet 210 and the positive electrode sheet 220, and the first separator 230 that is rolled in by the winding member 110 for one turn is stacked. and the second isolation film 240 , the second isolation film 240 is located on the inner side of the first isolation film 230 (that is, on the side close to the winding axis). The negative pole piece 210 enters between the first separator 230 and the second separator 240 after the separator is wound at least one turn, so as to be rolled into the winding part 110 . The length of the third separator 250 is shorter than the first separator 230 and the second separator 240, and the third separator 250 is separated from the second separator 240 from a side of the second separator 240 far away from the negative electrode sheet 210 before the positive electrode sheet 220 enters the winding part 110. The side enters the winding part 110. After the third separator 250 enters the winding part 110 , the positive electrode tab 220 is inserted between the second separator 240 and the third separator 250 to enter the winding part 110 .

It can be understood that a circle in this application refers to starting from a certain point of the electrode assembly 200 and going around in the winding direction to another point, and the line connecting the other point and the starting point is along the radial extension. The half circle in the present application refers to half of one circle, and those skilled in the art should understand the meaning of other circle numbers, and no further details are given here.

As shown in FIG. 1, the winding part 110 is used for winding and forming the electrode assembly 200, and four feeding mechanisms (not shown in the figure) are arranged on the incoming side of the winding part 110, and the four feeding mechanisms are respectively used for A negative electrode tab 210 , a positive electrode tab 220 , a first separator 230 and a second separator 240 are provided to the wound member 110 .

As shown in Figure 1, the winding part 110 includes a pair of winding needles 111, each winding needle 111 is in the shape of a semi-cylindrical or semi-elliptical cylinder, and the pair of rolling needles 111 are combined to form a cylindrical or elliptical cylindrical outer peripheral surface. The winding part 110 and a pair of winding needles 111 rotate together to stack and wind the first separator 230, the negative electrode sheet 210, the second separator 240, the positive electrode sheet 220 and the third separator 250 on the winding part 110 peripheral surface. Wherein, the rotation direction of the winding component 110 is the first direction P.

Some embodiments of the present application propose a winding device 100 for winding and forming an electrode assembly 200 . The winding device 100 includes a winding part 110 and a pulling mechanism 120 . The winding part 110 is used to wind the first separator 230, the negative electrode sheet 210, the second separator 240, the positive electrode sheet 220 and the third separator 250; the traction mechanism 120 is configured to roll in the positive electrode sheet Before the end 221 enters the winding part 110, the winding-in end 251 of the third separator is pulled to the winding part 110, so that the winding-in end 251 of the third separator enters the winding before the winding-in end 221 of the positive pole piece. Part 110.

It can be understood that the winding-in end 221 of the positive pole piece refers to the end of the positive pole piece 220 close to the winding axis, that is, the end of the positive pole piece 220 that first enters the winding part 110 . Similarly, the rolling-in end 251 of the third isolation film refers to the end of the third isolation film 250 close to the winding axis, that is, the end of the third isolation film 250 that first enters the winding component 110 .

There are many ways for the pulling mechanism 120 to pull the roll-in end 251 of the third separator to the winding part 110 . The traction mechanism 120 can drive the roll-in end 251 of the third isolation film to move by clamping, or can drive the roll-in end 251 of the third isolation film to move by vacuum suction.

The length of the roll-in end 251 of the third separator prior to the roll-in end 221 of the positive pole piece is not limited, as long as the third separator 250 has been wound around the roll-up component 110 when the positive pole piece 220 enters the roll-up component 110. Can.

The number of layers of the third separator 250 can be one layer; the number of layers of the separator between the innermost circle of the positive electrode sheet 220 and the inner negative electrode sheet 210 of the wound electrode assembly 200 is two layers. The number of layers of the third isolation film 250 can also be multi-layer. When the number of the third isolation film 250 is multi-layer, the multi-layer third isolation film 250 is stacked to form the third isolation film group. The third isolation film group The winding end is pulled by the traction mechanism 120 to enter the winding part 110 before the winding end 221 of the positive pole piece, which can further increase the layer of the separator between the innermost circle of the positive pole piece 220 and the inner negative pole piece 210 number, further improving the safety performance of the electrode assembly 200. For example, when the number of the third separator 250 is three layers, the number of separator layers between the innermost circle of the positive electrode sheet 220 and the inner negative electrode sheet 210 of the wound electrode assembly 200 is four layers.

The roll-in end 251 of the third isolation film can enter the winding part 110 in an entrained manner; the roll-in end 251 of the third separation film can also be bonded or hot-melt connected with the second isolation film 240 before entering the winding part 110 , and enter the winding part 110 synchronously with the second isolation film 240 .

After the winding end 251 of the third separator enters the winding part 110, the winding part 110 rotates to continue winding and forming the electrode assembly 200, and the third separator 250 is cut after the winding part 110 rotates several times to form the first Three ends 252 of the isolation membrane. The third separator 250 can be cut after the winding part 110 rotates one turn, so that the third separator 250 corresponds to the innermost circle of the positive pole piece 220, so as to protect the innermost circle of the positive pole piece 220. The two bending areas are not affected by lithium analysis; the third separator 250 can be cut after the winding part 110 rotates twice, so that the third separator 250 corresponds to the innermost ring and the positive pole piece 220 of the second inner ring , to protect the two bending areas of the positive pole piece 220 of the innermost circle and the second inner circle from the third separator 250 affected by lithium precipitation; it can also be cut after the winding part 110 rotates half a circle, only with the positive pole The first bending area on the side of the roll-in end 221 of the pole piece corresponds to that, and only the first bending area of the innermost positive pole piece 220 is protected from the influence of lithium precipitation.

The winding device 100 of some embodiments of the present application includes a pulling mechanism 120, and the pulling mechanism 120 can pull the winding end 251 of the third separator to the winding part before the winding end 221 of the positive pole piece enters the winding part 110 110, so that the roll-in end 251 of the third separator enters the winding part 110 prior to the roll-in end 221 of the positive electrode sheet, and the third separator 250 and the second separator 240 are stacked on the innermost of the positive electrode sheet 220 Between the ring and the negative pole piece 210 inside it. When the lithium precipitation phenomenon occurs, the lithium dendrites are not easy to pierce the separator to cause the contact between the negative pole piece 210 and the positive pole piece 220 , thereby causing an internal short circuit of the electrode assembly 200 . The electrode assembly 200 wound and formed by using the winding device 100 has high safety performance, and the winding device 100 can realize the industrial production of the electrode assembly 200 and improve the manufacturing efficiency of the electrode assembly 200 .

Fig. 3 shows a schematic structural view of the gluing mechanism of the winding device in a working position according to some embodiments of the present application.

In some embodiments of the present application, the winding device 100 further includes a glue application mechanism 130, and the glue application mechanism 130 is configured to apply a glue layer to the winding end 251 of the third isolation film; wherein, the third isolation film 250 and The second isolation film 240 is adjacently arranged, and the pulling mechanism 120 is configured to pull the roll-in end 251 of the third isolation film coated with an adhesive layer to the winding part 110, so that the roll-in end 251 of the third isolation film is in contact with the winding part 110. The second isolation film 240 is bonded by an adhesive layer.

Adjacent arrangement of the third isolation film 250 and the second isolation film 240 means that before entering the winding part 110 , the roll-in end 251 of the third isolation film is adjacent to the second isolation film 240 .

The glue application mechanism 130 can apply a glue layer to the winding end 251 of the third isolation film in the manner of spraying, pressing, or rolling. The gluing mechanism 130 can be fixedly installed, and the gluing mechanism 130 passes through the gluing mechanism 130 when the traction mechanism 120 pulls the third separator 250 to move, and the gluing mechanism 130 applies a glue layer to the roll-in end 251 of the third separator; 130 can also actively approach the third isolation film 250 to apply a glue layer to the roll-in end 251 of the third isolation film.

In the above scheme, the glue layer is first applied to the roll-in end 251 of the third separator by the glue application mechanism 130, and then the roll-in end 251 of the third separator is pulled to the winding part 110, and the roll-in end 251 of the third separator is pulled The roll-in end 251 and the second separator 240 are bonded by an adhesive layer, so that the third separator 250 can not only be introduced into the winding part 110 through the second separator 240, but also the roll-in end 251 of the third separator can be fixed on the second separator. The position on the second separator 240 ensures that the roll-in end 251 of the third separator exceeds the roll-in end 221 of the positive pole piece after the electrode assembly 200 is wound.

In other embodiments, the glue application mechanism 130 can also be configured to apply a glue layer to the surface of the second isolation film 240, the pulling mechanism 120 pulls the roll-in end 251 of the third isolation film to the winding part 110, and then The roll-in end 251 of the third isolation film is bonded to the second isolation film 240 through an adhesive layer.

Fig. 4 is a schematic diagram showing a state in which the gluing mechanism of the winding device is in a non-working position according to some embodiments of the present application.

As shown in Figures 3 and 4, in some embodiments of the present application, the gluing mechanism 130 is configured to switch between a working position and a non-working position, wherein, when the gluing mechanism 130 is in the working position, the gluing mechanism 130 is configured to switch between the working position and the non-working position. The mechanism 130 is used to apply a glue layer to the roll-in end 251 of the third separator; when the glue-applying mechanism 130 is in the non-working position, the roll-in end 251 of the glue-applying mechanism 130 away from the third separator is pulled by the traction mechanism 120 path of movement.

As shown in FIG. 3 , the working position is the position where the gluing mechanism 130 applies glue to the roll-in end 251 of the third separator; as shown in FIG. 4 , the non-working position is the initial position of the gluing mechanism 130 .

The moving path of the gluing mechanism 130 between the working position and the non-working position can be a straight line or a curve.

For example, as shown in FIG. 4 , in some embodiments of the present application, the gluing mechanism 130 moves from the non-working position to the working position along the second direction Q, and the moving path of the gluing mechanism 130 is a curve.

The gluing mechanism 130 can move between the working position and the non-working position in a manual manner, and can also move between the working position and the non-working position in an automated manner.

The winding device 100 also includes a guide rail assembly for guiding the gluing mechanism 130 to move between the working position and the non-working position. The gluing mechanism 130 is slidably mounted on the guide rail assembly to limit the movement path of the gluing mechanism 130 . The winding device 100 also includes a driving mechanism (not shown) for driving the gluing mechanism 130 to move between the working position and the non-position, so as to realize automatic driving of the gluing mechanism 130 to move

In the above scheme, the glue applying mechanism 130 can move to the non-working position after applying the glue layer to the roll-in end 251 of the third separator, so as to stay away from the moving path of the roll-in end 251 of the third separator, so that the third separator The roll-in end 251 of the separator moves smoothly to the winding part 110 under the traction of the traction mechanism 120 .

Fig. 5 is a schematic diagram showing the cooperation state of the traction mechanism and the support member in the winding device according to some embodiments of the present application.

As shown in FIG. 5 , in some embodiments of the present application, the winding device 100 further includes a support member 140, and the support member 140 is arranged on a side of the second separator 240 close to the negative pole piece 210; wherein, the traction mechanism 120 It is configured to press the roll-in end 251 of the third isolation film and the second isolation film 240 against the support member 140 so that the roll-in end 251 of the third isolation film and the second isolation film 240 are bonded by an adhesive layer.

Specifically, the side of the second separator 240 close to the negative electrode sheet 210 is the first side 241, and the side away from the negative electrode sheet 210 is the second side 242, and the support member 140 is arranged on the second side of the second separator 240. On one side 241 , the roll-in end 251 of the third isolation film is bonded to the second isolation film 240 from the second side 242 of the second isolation film 240 . The side of the support member 140 facing the first side 241 of the second isolation membrane 240 has a support surface 141, and the support surface 141 abuts against the first side 241 of the second isolation membrane 240 for receiving the pressing force exerted by the traction mechanism 120 .

In the above solution, after the pulling mechanism 120 pulls the rolling-in end 251 of the third separator to the winding part 110, the pulling mechanism 120 presses the rolling-in end 251 of the third separator and the second separator 240 to the support 140, to squeeze it from both sides of the roll-in end 251 of the third isolation film and the second isolation film 240, and reliably bond the roll-in end 251 of the third isolation film and the second isolation film 240 through the glue layer .

In other embodiments, another pressing mechanism can also be provided. After the pulling mechanism 120 pulls the roll-in end 251 of the third isolation membrane to the second side 242 of the second isolation membrane 240, the pressing mechanism acts on the third isolation membrane. The roll-in end 251 of the third isolation film is pressed against the support member 140 by the roll-in end 251 of the third isolation film and the second isolation film 240 .

Fig. 6 shows a schematic diagram of the pick-up part of the traction mechanism of the winding device picking up the roll-in end of the third separator according to some embodiments of the present application.

As shown in Fig. 4, Fig. 5 and Fig. 6, in some embodiments of the present application, the traction mechanism 120 includes a driving member (not shown in the figure) and a pick-up member 121, and the drive member is used to drive the pick-up member 121 in the first switch between position and second position. When the pick-up member 121 is at the first position, the pick-up member 121 picks up the roll-in end 251 of the third separator; The isolation film 240 is pressed toward the support 140 .

The moving path of the picker 121 between the first position and the second position may be a straight line or a curved line. In some embodiments of the present application, the picker 121 moves from the first position to the second position along the third direction N, the moving path of the picker 121 is a straight line, and the drive is a linear drive such as a linear cylinder or an electric push rod. . In other embodiments, the moving path of the picking member 121 is a curve, and the driving member is a driving mechanism such as a crank linkage mechanism or a cam mechanism.

The pick-up piece 121 can be a part of the claw type, which clamps the roll-in end 251 of the third separation film 250 from both sides in the thickness direction of the third separation film 250; One side of the thickness direction of the third separator 250 is adsorbed to the roll-in end 251 of the third separator.

Please refer to Fig. 4, the first position is the position where the pick-up member 121 picks up the roll-in end 251 of the third separator, and picks up the third separator before the glue application mechanism 130 applies glue to the roll-in end 251 of the third separator. The roll-in end 251; please refer to FIG. 5, the second position is that the pick-up part 121 pulls the roll-in end 251 of the third isolation film to reach the second isolation film 240, so that the adhesive layer on the surface of the third isolation film 250 and the second isolation film The position when the second side 242 of 240 is in contact.

When the pick-up member 121 moves to the second position, the pick-up member 121 can vacuum-adsorb the roll-in end 251 of the third separator 250 from the side of the third separator 250 away from the second separator 240, and roll the roll-in end 251 of the third separator 250. The end 251 is directly pressed against the support member 140 after being in contact with the second isolation film 240; the pick-up member 121 may also have a Two states.

In the above solution, the driving member can automatically drive the pick-up member 121 to switch between the first position and the second position, so as to automatically execute the action of pulling the roll-in end 251 of the third separator to the winding part 110, thereby realizing The winding equipment 100 automatically winds and forms the electrode assembly 200 of this structure.

As shown in FIG. 6 , in some embodiments of the present application, the picker 121 includes a pair of clamping parts 1211 for clamping the third isolation film 250 .

The pair of clamping parts 1211 can be cylinder jaws or electric jaws, and the pair of clamping parts 1211 are used to clamp the roll-in end 251 of the third isolation film 250 from both sides in the thickness direction of the third isolation film 250 .

In the above scheme, a pair of clamping parts 1211 are used to clamp the third separator 250 to pull the roll-in end 251 of the third separator to move, and the process of pulling the roll-in end 251 of the third separator to move is stable and reliable. , the roll-in end 251 of the third isolation film is not easily separated from the pick-up member 121 .

As shown in FIG. 4 and FIG. 5 , in some embodiments of the present application, the pickup member 121 is rotatably mounted on the output end of the driving member, so as to have different postures at the first position and the second position respectively.

Specifically, the picker 121 has a first state and a second state. As shown in FIG. 4 , the pick-up member 121 is in the first state when it is at the first position; as shown in FIG. 5 , it is in the second state when the pick-up member 121 is at the second position. The picker 121 may be in the second state during the process of picking up the roll-in end 251 of the third separator and pulling the roll-in end 251 of the third separator. Turn to the second state after the second position, and press the roll-in end 251 of the third separator; The roll-in end 251 of the film rotates from the first state to the second state during the movement, and is already in the second state before reaching the second position, and directly presses the roll-in end 251 of the third isolation film after reaching the second position .

In the above solution, since the pick-up member 121 can be switched between two states by rotating, one state is used to clamp and pull the rolling end 251 of the third separator to move, and the other state is used to clamp The rolled-in end 251 of the third isolation film presses the rolled-in end 251 of the third isolation film and the second isolation film 240 toward the supporting member 140 . The action of pulling the roll-in end 251 of the third separator to move and the action of pressing the roll-in end 251 of the third separator and the second separator 240 to the support 140 are completed by using a pick-up member 121, which reduces winding The number of parts of the device 100 simplifies the construction of the winding device 100 .

Fig. 7 is a schematic diagram showing a state of cutting a third separator by a cutting mechanism of a winding device according to some embodiments of the present application.

As shown in FIG. 7 , in some embodiments of the present application, the winding device 100 further includes a cutting mechanism 150 for cutting the third isolation film 250 .

After the cutting mechanism 150 cuts the third isolation film 250, a tail end 252 of the third isolation film is formed (as shown in FIG. 2 ). The cutting mechanism 150 is disposed between the feeding mechanism of the third isolation film 250 and the winding component 110 , that is, on the traveling path of the third isolation film 250 . The cutting mechanism 150 can be a knife assembly including a fixed knife and a moving knife set opposite to each other, or a knife assembly including two moving knives set opposite to each other.

In the above scheme, by setting the cutting mechanism 150, the third separator 250 can be cut in time, so that the third separator 250 can be entangled only in the innermost circles of the electrode assembly 200, which not only overcomes the inner circle of the electrode assembly 200. The problem of lithium crystallization piercing the isolation film during lithium analysis can improve the safety performance of the electrode assembly 200, save the amount of the third isolation film 250, and improve the energy density of the electrode assembly 200.

As shown in FIGS. 6 and 7 , in some embodiments of the present application, the winding device 100 further includes a roll 160 for carrying the third isolation film 250 .

The roll 160 is a feeding mechanism for the third isolation film 250 and is used to provide the third isolation film 250 in roll form.

As shown in FIG. 6, when the pick-up piece 121 is in the first position, the pick-up piece 121 is located on the lower side of the reel 160, and the roll-in end 251 of the third separator hangs down by gravity, so that the pick-up piece 121 can accurately pick up the entry point of the separator. roll end.

In the above solution, the third isolation film 250 is supplied in the form of roll material by setting the roll 160 to carry the third isolation film 250 , which has a simple structure and is easy to implement.

FIG. 8 shows a process flow diagram of a winding method according to some embodiments of the present application.

Some embodiments of the present application propose a winding method for winding and forming an electrode assembly 200. The electrode assembly 200 includes a first separator 230, a negative electrode sheet 210, a second separator 240, and a positive electrode sheet that are sequentially stacked. 220 and the third isolation film 250 , the length of the third isolation film 250 is smaller than that of the first isolation film 230 and the second isolation film 240 .

As shown in Figure 8, the winding method includes:

S100: Before the roll-in end 221 of the positive pole piece enters the roll-up part 110, draw the roll-in end 251 of the third separator to the roll-up part 110, so that the roll-in end 251 of the third separator is ahead of the positive electrode. The roll-in end 221 of the sheet enters the winding part 110 .

It can be understood that, the winding method in the embodiment of the present application includes but is not limited to implementing by using the winding device 100 in the embodiment of the present application.

Specifically, S100: before the winding end 221 of the positive pole piece enters the winding part 110, pull the winding end 251 of the third separator to the winding part 110, so that the winding end 251 of the third separator Before the roll-in end 221 of the positive pole piece enters the winding part 110, it includes:

S110: Pull the roll-in end 251 of the third separator to the winding part 110, and position it on the side of the second separator 240 away from the negative electrode assembly;

S120: Make the roll-in end 251 of the third isolation film enter the winding part 110;

S130 : the roll-in end 221 of the positive pole piece is inserted between the second separator 240 and the third separator 250 to enter the winding part 110 .

Using the winding method of the embodiment of the present application to wind and form the electrode assembly 200, the winding end 251 of the third separator can enter the winding part 110 before the winding end 221 of the positive electrode sheet, and the third separator 250 and the first The two separators 240 are stacked between the innermost ring of the positive electrode sheet 220 and the inner negative electrode sheet 210 . When the lithium precipitation phenomenon occurs, the lithium dendrites are not easy to pierce the separator to cause the contact between the negative pole piece 210 and the positive pole piece 220 , thereby causing an internal short circuit of the electrode assembly 200 . The electrode assembly 200 wound and formed by this winding method has high safety performance.

As shown in FIG. 8, in some embodiments of the present application, the third isolation film 250 is arranged adjacent to the second isolation film 240, and the winding method further includes:

S200: Paste or thermally fuse the roll-in end 251 of the third isolation film to the second isolation film 240 .

In some embodiments of the present application, S200: Paste or thermally fuse the roll-in end 251 of the third isolation film to the second isolation film 240, including:

S210: Apply an adhesive layer to the roll-in end 251 of the third isolation film;

S220: Pull the roll-in end 251 of the third separator to the winding part 110, so that the roll-in end 251 of the third separator is adjacent to the second separator 240;

S230: Bond the roll-in end 251 of the third isolation film to the second isolation film 240 through an adhesive layer.

In other embodiments of the present application, S200: Paste or thermally fuse the roll-in end 251 of the third isolation film to the second isolation film 240, including:

S240: Pull the roll-in end 251 of the third separator to the winding part 110, so that the roll-in end 251 of the third separator is adjacent to the second separator 240;

S250: bonding the roll-in end 251 of the third isolation film to the second isolation film 240 by hot-melt bonding.

In some embodiments of the present application, S200: Paste or thermally fuse the roll-in end 251 of the third isolation film to the second isolation film 240, including:

S260: the picker 121 moves from the first position to the second position in the first state, and pulls the roll-in end 251 of the third separator to the winding part 110;

S270: The picker 121 presses the roll-in end 251 of the third isolation film and the second isolation film 240 against the support member 140 in the second state, so that the roll-in end 251 of the third isolation film and the second isolation film 240 pass through the glue Layer bonding or hot melt joining.

In the above solution, the winding-in end 251 of the third separator and the second separator 240 are connected by pasting or hot-melting, so that not only the third separator 250 can be introduced into the winding part 110 through the second separator 240, but also The position of the roll-in end 251 of the third separator on the second separator 240 can be fixed to ensure that the roll-in end 251 of the third separator exceeds the roll-in end 221 of the positive pole piece after the electrode assembly 200 is wound.

As shown in Figure 8, in some embodiments of the present application, the winding method also includes:

S300: Cut the third isolation film 250 after the third isolation film 250 is wound at least one turn.

In the above scheme, after the third separator 250 is wound at least one turn, two layers of separators are stacked between the innermost circle of the positive electrode sheet 220 and the inner negative electrode sheet 210, thereby avoiding the positive electrode sheet Lithium crystallization pierces the separator when lithium is deposited inside the innermost circle of 220 , which can significantly improve the safety performance of the electrode assembly 200 , save the amount of the third separator 250 , and increase the energy density of the electrode assembly 200 .

As shown in FIGS. 1 to 8 , some embodiments of the present application provide a winding device 100 for winding and forming an electrode assembly 200 . The winding device includes a winding component 110 , a pulling mechanism 120 , a gluing mechanism 130 , a support 140 , a cutting mechanism 150 and a reel 160 . The traction mechanism 120 includes a pick-up member 121 , and the pick-up member 121 includes a pair of clamping portions 1211 . The picker 121 switches between the first position and the second position. When the picker 121 is in the first position, the picker is in the first state; when the picker 121 is in the second position, the picker 121 is in the second state. The gluing mechanism 130 is switched between the working position and the non-working position. The roll 160 is used to carry the third isolation film 250 in roll form.

The winding process of the winding device 100 is as follows:

The winding part 110 rotates along the first direction P, and rolls in the first isolation film 230 and the second isolation film 240 at least one turn;

The negative pole piece 210 enters the winding part 110 from between the first separator 230 and the second separator 240, and is wound at least once;

The picker 121 clamps the roll-in end 251 of the third separator at the first position, and the glue application mechanism 130 moves from the non-working position to the working position along the second direction Q, and applies glue to the roll-in end 251 of the third separator. layer, after the action of coating the glue layer is completed, the glue applying mechanism 130 is reset to the non-working position;

The picker 121 moves from the first position to the second position along the third direction N, and switches from the first state to the second state, moving the roll-in end 251 of the third isolation film to the second side of the second isolation film 240 242;

The pick-up part 121 presses the roll-in end 251 of the third separator and the second separator 240 against the support member 140, so that the roll-in end 251 of the third separator and the second separator 240 are bonded by an adhesive layer;

The picker 121 releases the roll-in end 251 of the third separator and resets to the first position;

The winding part 110 continues to wind, so as to drive the roll-in end 251 of the third separating film through the second separating film 240 to enter the winding part 110;

After the negative pole piece 210 is wound once, the positive pole piece 220 enters the winding part 110 from between the second separator 240 and the third separator 250;

The positive pole piece 220 continues to be wound, and the cutting mechanism 150 cuts the third separator 250 to form the ending end 252 of the third separator, and the length of the third separator 250 is at least one time the circumference of the winding part 110;

The winding part 110 continues to be wound to shape the electrode assembly 200 .

The winding device 100 and the winding method of the embodiment of the present application can form an electrode assembly 200 with a special structure. The structure of the winding device 100 is simple, and the winding method is easy to implement. The inner ring of the electrode assembly 200 has a multi-layer separator , can prevent short-circuiting of cathode and anode due to lithium precipitation due to the imbalance between the positive electrode active material capacity of the positive electrode sheet 220 and the negative electrode active material capacity of the corresponding negative electrode sheet 210 .

While the application has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the application. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims (12)

1. A winding device for winding and forming an electrode assembly. The electrode assembly includes a first separator, a negative electrode sheet, a second separator, a positive electrode sheet, and a third separator that are sequentially stacked. The length of the isolation film is shorter than the first isolation film and the second isolation film, and the winding device includes:

   a winding part for winding the first separator, the negative electrode sheet, the second separator, the positive electrode sheet, and the third separator;

   a pulling mechanism configured to pull the rolled-in end of the third separator to the winding part before the rolling-in end of the positive pole piece enters the winding part, so that the third separator The roll-in end of the film enters the winding part before the roll-in end of the positive pole piece.
2. The winding device according to claim 1, wherein said winding device further comprises:

   a glue application mechanism configured to apply a glue layer to the roll-in end of the third separator;

   Wherein, the third isolating film is arranged adjacent to the second isolating film, and the pulling mechanism is configured to pull the roll-in end of the third isolating film coated with the adhesive layer to the roll Winding parts, so that the roll-in end of the third isolation film is bonded to the second isolation film through the adhesive layer.
3. The winding device according to claim 2, wherein the gluing mechanism is configured to switch between a working position and a non-working position, wherein:

   When the gluing mechanism is at the working position, the gluing mechanism is used to apply the adhesive layer to the roll-in end of the third separator;

   When the gluing mechanism is at the non-working position, the gluing mechanism is far away from the movement path of the roll-in end of the third separator under the traction of the traction mechanism.
4. The winding device according to claim 2 or 3, wherein the winding device further comprises:

   a support member disposed on a side of the second separator close to the negative electrode sheet;

   Wherein, the traction mechanism is configured to press the rolled-in end of the third separator and the second separator to the support member, so that the rolled-in end of the third separator and the second separator The films are bonded by the adhesive layer.
5. The winding device according to claim 4, wherein the traction mechanism comprises a driving member and a pick-up member, the drive member is used to drive the pick-up member to switch between the first position and the second position, when the When the pick-up is at the first position, the pick-up picks up the roll-in end of the third separator, and when the pick-up is at the second position, the pick-up takes the third separator The rolling end of and the second separator are pressed against the support.
6. The winding apparatus according to claim 5, wherein the pick-up member includes a pair of clamping portions for clamping the third separator.
7. The winding device according to claim 5 or 6, wherein the pick-up member is rotatably mounted on the output end of the drive member to have different postures in the first position and the second position, respectively .
8. The winding device according to any one of claims 1-7, wherein the winding device further comprises:

   The cutting mechanism is used for cutting the third isolation film.
9. The winding device according to any one of claims 1-8, wherein the winding device further comprises:

   The roll is used to carry the third isolation film.
10. A winding method for winding and forming an electrode assembly. The electrode assembly includes a first separator, a negative electrode sheet, a second separator, a positive electrode sheet, and a third separator that are sequentially stacked. The length of the isolation film is shorter than the first isolation film and the second isolation film, and the winding method includes:

    Before the roll-in end of the positive pole piece enters the roll-up part, the roll-in end of the third separator is drawn to the roll-up part, so that the roll-in end of the third separator is ahead of the roll-in end of the third separator. The winding end of the positive pole piece enters the winding part.
11. The winding method according to claim 10, wherein the third isolation film is disposed adjacent to the second isolation film, and the winding method further comprises:

    Paste or thermally fuse the roll-in end of the third isolation film to the second isolation film.
12. The winding method according to claim 10 or 11, wherein the winding method further comprises:

    After the third separator is wound at least one turn, the third separator is cut.

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