Pole-lug-free cylindrical battery and preparation method thereof

Abstract

The invention belongs to the technical field of cylindrical battery structures, and particularly relates to a tab-free cylindrical battery and a preparation method thereof. Comprising an upper cover, a shell, a roll core and a composite current collector, the roll core and the composite current collector are arranged in the shell, the upper cover is located at the top of the shell, and an upper pole is arranged on the upper cover; the composite current collectors are respectively arranged at two ends of the roll core, the composite current collector positioned at the top end of the roll core is connected with a contact surface of an upper pole on the upper cover, and the composite current collector positioned at the bottom end of the roll core is connected with the bottom of the shell; the roll core is formed by winding a positive plate, a negative plate and a roll core diaphragm; each of the positive plate and the negative plate is composed of a conductive adhesive, an active substance material layer and a composite current collector, and the composite current collector is composed of a high polymer material layer and conductive metal material layers located on the two sides of the high polymer material layer; the problems that the composite current collector is broken, layered, warped and difficult to weld in the rubbing process of the cylindrical battery composite current collector can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of cylindrical battery structures, and in particular relates to a tab-free cylindrical battery and a preparation method thereof. Background Art

[0002] In recent years, cylindrical batteries have been widely used in power vehicles, power tools, household energy storage and other fields due to their high energy density and long driving range. Traditional cylindrical lithium batteries use aluminum foil and copper foil as current collectors, which have poor safety and may cause fire and explosion under extreme conditions such as puncture. For this reason, the industry has introduced a composite current collector, in which metal layers such as copper and aluminum are plated on both sides of the polymer layer. The introduction of the polymer layer is beneficial to improving the energy density and safety performance of the battery. However, the bonding between polymer materials and metals is poor. Commonly used polymer materials are generally straight chains and tend to show elasticity to the outside. Therefore, the use of traditional tab-free flattening process is prone to rupture, delamination, warping and other problems of the composite current collector, affecting the subsequent connection with the metal shell, increasing the internal resistance of the battery, and even bringing safety hazards. In addition, the metal layer is thin, and the use of traditional welding methods is prone to poor welding. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a tab-free cylindrical battery and a preparation method thereof, so as to solve the problems of composite current collector rupture, stratification, warping and difficulty in welding during the flattening process of the composite current collector of the cylindrical battery.

[0004] The object of the present invention is achieved as follows: A tab-free cylindrical battery comprises an upper cover, a shell, a winding core and a composite current collector, wherein the winding core and the composite current collector are both arranged in the shell, the upper cover is located on the top of the shell, and an upper pole is arranged on the upper cover; The composite current collectors are respectively arranged at both ends of the winding core, the composite current collector located at the top of the winding core is connected to the contact surface of the upper pole on the upper cover, and the composite current collector located at the bottom of the winding core is connected to the bottom of the shell; the winding core is wound by the positive electrode sheet, the negative electrode sheet and the winding core separator; The positive electrode sheet and the negative electrode sheet are both composed of a conductive glue, an active material layer and the composite current collector, and the composite current collector is composed of a polymer material layer and conductive metal material layers located on both sides of the polymer material layer.

[0005] Furthermore, the core is formed by winding the positive electrode sheet, the negative electrode sheet and the core separator by a winding machine, and the core separator includes a first separator and a second separator.

[0006] Furthermore, the active material layer is composed of active material coated and bonded to both sides of the composite current collector.

[0007] Furthermore, there is an area on the surface of the composite current collector where the active material is not coated, and the conductive adhesive is coated on the side and end surfaces of the composite current collector where the active material is not coated.

[0008] Furthermore, the conductive metal material layer is made of a surface-coated metal foil, nickel foam or stainless steel.

[0009] Furthermore, the conductive adhesive is a homogeneous conductive adhesive liquid formed by mixing a conductor and an adhesive.

[0010] Furthermore, the conductor is a mixture of one or more of low-resistance metal powder, graphene and other carbon materials with good conductivity, and the adhesive is a viscous liquid composed of a mixture of polymer materials resistant to electrolyte corrosion such as epoxy resin.

[0011] A method for preparing a tab-free cylindrical battery comprises the following steps: S1, coating the active material on both sides of the composite current collector, leaving an uncoated area on the composite current collector, and rolling and compacting after drying to form a negative electrode sheet or a positive electrode sheet with close contact and strong adhesion, and coating the conductive glue on the side and end surface of the composite current collector where the active material is not coated, while coating the active material, wherein the thickness of the conductive glue layer is less than the thickness of the electrode material; S2, winding the positive electrode sheet, the negative electrode sheet, the first separator, and the second separator into a winding core by a winding machine, wherein the uncoated active material area of ​​the composite current collector in the positive and negative electrode sheets is located outside the winding core separator and is respectively located at both ends of the winding core separator and extends out of the winding core separator by a certain length; S3. Flatten the uncoated active material area of ​​the composite current collector extending out of the core diaphragm, then place the core into the shell and close the upper cover, the upper end of the core contacts the contact surface of the pole through the conductive glue, the lower end of the core contacts the bottom of the shell through the conductive glue, and achieve tight bonding through curing methods such as pressurization and heating.

[0012] Furthermore, in the step S1, when the conductive adhesive is coated on the side and end surfaces of the composite current collector where no active material is coated, the conductive adhesive is coated on part of the side and end surfaces of the composite current collector where no active material is coated.

[0013] Beneficial effects of the present invention: The present invention adopts a tab-free cylindrical battery, through structural optimization, so that the composite current collectors of the positive and negative electrode sheets of the winding core are leaked out for a certain length and are directly electrically connected to the bottom of the shell and the pole respectively, reducing the positive and negative pole column components, eliminating the positive and negative busbars, simplifying the production process and reducing the production cost; the present invention adopts an adhesive conductive adhesive to replace the tab welding method, eliminating the welding process, not only solving the risks of temperature rise, welding slag, welding penetration and other risks that affect the safety of the battery cell, but also reducing the purchase and maintenance costs of welding equipment; the conductive adhesive is located at the same The conductive adhesive of the present invention is composed of a conductive body and an adhesive body at the layer, has a simple structure, is efficient and convenient to bond, has good conductivity, adhesion and flexibility, and ensures that the positive and negative current collectors are firmly bonded to the bottom of the shell and the pole and that they are electrically connected reliably; after the conductive adhesive of the present invention is applied, the problems of collector delamination, metal layer rupture and flattening interface warping during the flattening process of the positive and negative current collectors can be significantly reduced, thereby improving the product yield and reducing the local internal resistance of the battery; the conductive adhesive of the present invention melts at a high temperature, and when a short circuit occurs in the battery cell, the connection between the positive and negative electrodes and the pole or the bottom of the shell can be disconnected in time, thereby breaking the circuit and enhancing safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic diagram of the structure of a composite current collector in one embodiment of the present invention; Figure 2 for Figure 1 Schematic diagram of the planar structure of the composite current collector in the embodiment; Figure 3 for Figure 1 A schematic diagram of the winding core structure in the embodiment; Figure 4 for Figure 1 A schematic diagram of the structure of a cylindrical battery in an embodiment; Figure 5 A schematic diagram of the structure of a composite current collector in another embodiment of the present invention; Figure 6 for Figure 5 Schematic diagram of the planar structure of the composite current collector in the embodiment; Figure 7 for Figure 5 A schematic diagram of the winding core structure in the embodiment; Figure 8 for Figure 5 A schematic structural diagram of a cylindrical battery in an embodiment. DETAILED DESCRIPTION

[0015] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] It should be noted that all directional indications in the embodiments of the present invention (such as up-down-left-right-front-back...) are only used to explain the relative position relationship - movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. The connection can be a direct connection or an indirect connection.

[0018] like Figure 1-8 As shown, a tab-free cylindrical battery comprises an upper cover 8, a shell 9, a winding core 10 and a composite current collector 3, wherein the winding core 10 and the composite current collector 3 are both arranged in the shell 9, the upper cover 8 is located on the top of the shell 9, and an upper pole 7 is arranged on the upper cover 8; The composite current collector 3 is respectively arranged at both ends of the winding core 10, the composite current collector 3 located at the top of the winding core 10 is connected to the contact surface of the upper pole 7 on the upper cover 8, and the composite current collector 3 located at the bottom of the winding core 10 is connected to the bottom of the shell 9, which can reduce the positive and negative pole column components and eliminate the positive and negative busbars, thereby simplifying the production process and reducing the production cost; the winding core 10 is wound by the positive electrode sheet, the negative electrode sheet and the winding core separator 6; The positive electrode sheet and the negative electrode sheet are both composed of a conductive glue 1 , an active material layer 2 and the composite current collector 3 . The composite current collector 3 is composed of a polymer material layer 4 and conductive metal material layers 5 located on both sides of the polymer material layer 4 .

[0019] Furthermore, in one embodiment, the core 10 is formed by winding the positive electrode sheet, the negative electrode sheet and the core separator by a winding machine, and the core separator includes a first separator and a second separator.

[0020] Furthermore, in one embodiment, the active material layer 2 is composed of active material coated and bonded to both sides of the composite current collector 3 .

[0021] Furthermore, in one embodiment, there is an area on the surface of the composite current collector 3 where the active material is not coated, and the conductive adhesive 1 is coated on the side and end surfaces of the composite current collector 3 where the active material is not coated. Adhesive conductive adhesive 1 is used to replace the tab welding method, eliminating the welding process, which not only solves the risks of temperature rise, welding slag, welding penetration, etc. that affect the safety of the battery cell, but also reduces the procurement and maintenance costs of welding equipment.

[0022] Furthermore, in one embodiment, the conductive metal material layer 5 is made of a surface-coated metal foil, nickel foam or stainless steel.

[0023] Furthermore, in one embodiment, the conductive adhesive 1 is a homogeneous conductive adhesive liquid mixed with a conductor and an adhesive, which has a simple structure, efficient and convenient bonding, good conductivity, adhesion and flexibility, and ensures that the positive and negative current collectors are firmly bonded to the bottom of the shell 9 and the pole 7 and have reliable electrical connection.

[0024] Furthermore, in one embodiment, the conductor is a mixture of one or more of low-resistance metal powder, graphene and other carbon materials with good conductivity, and the adhesive is a viscous liquid composed of a mixture of polymer materials resistant to electrolyte corrosion such as epoxy resin. After the conductive adhesive 1 is applied, the problems of current collector delamination, metal layer rupture, and flattening interface warping during the flattening process of the positive and negative current collectors can be significantly reduced, the product yield can be improved, and the local internal resistance of the battery can be reduced; the conductive adhesive of the present invention melts at high temperature, and when a short circuit occurs in the battery cell, the connection between the positive and negative electrodes and the pole 7 or the bottom of the shell 9 can be disconnected in time, thereby breaking the circuit and enhancing safety.

[0025] A method for preparing a tab-free cylindrical battery comprises the following steps: S1, coating the active material on both sides of the composite current collector 3, leaving an uncoated area on the composite current collector 3, and rolling and compacting after drying to form a negative electrode sheet or a positive electrode sheet with close contact and strong adhesion, and coating the conductive glue 1 on the side and end surface of the composite current collector 3 where the active material is not coated, while coating the active material. The thickness of the conductive glue 1 layer is less than the thickness of the electrode material; S2, the positive electrode sheet, the negative electrode sheet, the first separator, and the second separator are wound into a winding core 10 by a winding machine, and the uncoated active material area of ​​the composite current collector 3 in the positive and negative electrode sheets is located outside the winding core separator 6 and respectively located at the two ends of the winding core separator 6 and extends out of the winding core separator 6 by a certain length; when winding, the first separator and the second separator are first fed into the winding needle and rolled for a certain length, and then the negative electrode sheet is fed into the winding needle, and the positive electrode sheet is fed into the winding needle after the negative electrode sheet reaches a certain feeding length. Under the continuous rotation of the winding needle, the positive and negative electrode lengths reach the set value and are cut off. The negative electrode sheet at the cutting point exceeds a certain length compared with the positive electrode sheet, and finally the first separator and the second separator continue to be wound to a set length and then cut off; S3. Flatten the uncoated active material area of ​​the composite current collector 3 extending out of the core separator 6, then place the core 10 into the shell 9 and close the upper cover 8. The upper end of the core 10 contacts the contact surface of the pole 7 through the conductive adhesive 1, and the lower end of the core 10 contacts the bottom of the shell 9 through the conductive adhesive 1, and achieves tight bonding through curing methods such as pressurization and heating.

[0026] Furthermore, in one embodiment, in the step S1, when the conductive adhesive 1 is coated on the side and end surfaces of the composite current collector 3 where the active material is not coated, the conductive adhesive 1 is coated on part of the side and end surfaces of the composite current collector 3 where the active material is not coated.

[0027] In summary, the present invention adopts a tab-free cylindrical battery, through structural optimization, so that the composite current collectors of the positive and negative electrode sheets of the winding core 10 are leaked out for a certain length and are directly electrically connected to the bottom of the shell 9 and the pole 7 respectively, reducing the positive and negative pole column components, eliminating the positive and negative busbars, simplifying the production process and reducing the production cost; the present invention adopts an adhesive conductive adhesive 1 to replace the tab welding method, eliminating the welding process, not only solving the risks of temperature rise, welding slag, welding penetration and other risks that affect the safety of the battery cell, but also reducing the purchase and maintenance costs of welding equipment; the conductive adhesive is located at the same level The conductive adhesive 1 is composed of a conductor and an adhesive, has a simple structure, is efficient and convenient to bond, has good conductivity, adhesion and flexibility, and ensures that the positive and negative current collectors are firmly bonded to the bottom of the shell 9 and the pole 7 and are reliably electrically connected. After the conductive adhesive 1 of the present invention is applied, the problems of collector stratification, metal layer rupture, and flattening interface warping during the flattening process of the positive and negative current collectors can be significantly reduced, thereby improving the product yield and reducing the local internal resistance of the battery. The conductive adhesive of the present invention melts at high temperatures, and can promptly disconnect the connection between the positive and negative electrodes and the pole 7 or the bottom of the shell 9 when a short circuit occurs in the battery cell, thereby breaking the circuit and enhancing safety.

[0028] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0029] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A tab-free cylindrical battery, comprising an upper cover (8), a housing (9), a winding core (10) and a composite current collector (3), characterized in that: The winding core (10) and the composite current collector (3) are both arranged in the shell (9), the upper cover (8) is located on the top of the shell (9), and an upper pole (7) is arranged on the upper cover (8); The composite current collector (3) is respectively arranged at both ends of the winding core (10); the composite current collector (3) located at the top end of the winding core (10) is connected to the contact surface of the upper pole (7) on the upper cover (8); and the composite current collector (3) located at the bottom end of the winding core (10) is connected to the bottom of the shell (9); the winding core (10) is formed by winding a positive electrode sheet, a negative electrode sheet and a winding core separator (6); The positive electrode sheet and the negative electrode sheet are both composed of a conductive glue (1), an active material layer (2) and the composite current collector (3); the composite current collector (3) is composed of a polymer material layer (4) and conductive metal material layers (5) located on both sides of the polymer material layer (4).

2. A tab-free cylindrical battery as claimed in claim 1, characterized in that: The winding core (10) is formed by winding the positive electrode sheet, the negative electrode sheet and the winding core separator by a winding machine, and the winding core separator includes a first separator and a second separator.

3. The tab-free cylindrical battery according to claim 1, characterized in that: The active material layer (2) is composed of active material coated and bonded to both sides of the composite current collector (3).

4. A tab-free cylindrical battery as claimed in claim 3, characterized in that: There is an area on the surface of the composite current collector (3) that is not coated with the active material, and the conductive glue (1) is coated on the side and end surfaces of the area on the composite current collector (3) that is not coated with the active material.

5. The tab-free cylindrical battery according to claim 1, characterized in that: The conductive metal material layer (5) is made of a surface-coated metal foil, nickel foam or stainless steel.

6. The tab-free cylindrical battery according to claim 1, characterized in that: The conductive adhesive (1) is a homogeneous conductive adhesive liquid formed by mixing a conductor and an adhesive.

7. The tab-free cylindrical battery according to claim 6, characterized in that: The conductor is a mixture of one or more of low-resistance metal powder, graphene and other carbon materials with good conductivity, and the adhesive is a viscous liquid composed of a mixture of polymer materials resistant to electrolyte corrosion such as epoxy resin.

8. A method for preparing a tab-free cylindrical battery according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, coating the active material on both sides of the composite current collector (3), leaving an uncoated area on the composite current collector (3), drying and rolling and compacting, and coating the conductive glue (1) on the side and end surfaces of the composite current collector (3) where the active material is not coated, while coating the active material, wherein the thickness of the conductive glue (1) layer is less than the thickness of the electrode material; S2, winding the positive electrode sheet, the negative electrode sheet, the first separator, and the second separator into a winding core (10) by a winding machine, wherein the uncoated active material area of ​​the composite current collector (3) in the positive and negative electrode sheets is located outside the winding core separator (6) and is respectively located at two ends of the winding core separator (6) and extends out of the winding core separator (6) by a certain length; S3. The uncoated active material area of ​​the composite current collector (3) extending out of the winding core separator (6) is flattened, and then the winding core (10) is placed in the shell (9) and the upper cover (8) is closed, the upper end of the winding core (10) contacts the contact surface of the pole (7) through the conductive glue (1), and the lower end of the winding core (10) contacts the bottom of the shell (9) through the conductive glue (1).

9. The method for preparing a tab-free cylindrical battery according to claim 8, characterized in that: In the step S(1), when the conductive adhesive (1) is applied to the side and end surfaces of the composite current collector (3) in the area not coated with the active material, the conductive adhesive (1) is applied to part of the side and end surfaces of the composite current collector (3) in the area not coated with the active material.

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