CN214477802U

CN214477802U - Positive electrode sheet assembly, wound product, and press molding apparatus

Info

Publication number: CN214477802U
Application number: CN202120789052.7U
Authority: CN
Inventors: 谢红卫; 马祖华
Original assignee: NINGBO GP ENERGY CO Ltd
Current assignee: NINGBO GP ENERGY CO Ltd
Priority date: 2021-04-13
Filing date: 2021-04-13
Publication date: 2021-10-22
Anticipated expiration: 2031-04-13

Abstract

The utility model discloses an anode plate assembly, a winding product and punch forming equipment, wherein an anode tab with a rectangular cross section is selected and welded on one side surface of the anode plate; manufacturing a positive plate assembly; stamping a welding section on a positive pole lug of the positive pole piece assembly by utilizing a stamping process, so that the welding section of the positive pole lug and a corresponding positive pole piece part are formed into a bent structure; the punched positive plate component, the diaphragm and the punched negative plate are sequentially superposed and then subjected to winding process treatment; the bending curvature of the positive plate where the positive pole lug is located after winding is consistent with the bending curvature formed by punching the welding section, and a wound product is finally formed; the advantage has prevented the injury of positive plate by anodal utmost point ear limit portion, and the anodal piece laminating degree of anodal utmost point ear both sides is better, and the circularity of whole coiling article is better, is favorable to improving the electrical property of lithium cell.

Description

Positive electrode sheet assembly, wound product, and press molding apparatus

Technical Field

The utility model relates to a lithium metal battery field especially relates to the coiling article forming method of lithium cell.

Background

The lithium battery is mainly applied to the fields of electric appliances such as cameras, smoke alarm, gas meters, electricity meters and water meters, which require large capacity, long storage time and wide working temperature range.

The traditional lithium battery comprises a metal shell, a winding product and a sealing body; the winding product comprises a positive plate, first diaphragm paper, a negative plate and second diaphragm paper, and the positive plate, the first diaphragm paper, the negative plate and the second diaphragm paper are curled, so that the effect of isolating the positive plate from the negative plate can be met; the windings are then taped to prevent the windings from spreading. The negative pole tab is led out from the negative pole piece and connected with the bottom of the steel shell, and the positive pole tab is led out from the positive pole piece and connected with the positive pole terminal.

Related literature, negative electrode sheet for lithium battery with publication number CN 208045606U;

a battery roll product of publication No. CN 106229527B;

a battery roll product of publication No. CN 209709085U;

as shown in fig. 1, the cross section of the conventional whole positive electrode tab a is rectangular, the welding surface of the positive electrode tab a and the positive electrode sheet B has two right angles, and after a wound product is wound, as shown in fig. 2; there are the following problems: 1. the right-angle edge part of the positive electrode tab A can cause damage such as puncture, fracture and the like to the positive electrode tab B; the wound battery cell has a gap generated by supporting at the right-angle edge part of the lug, which can influence the contact between the positive plate B and the negative plate C of the battery cell, thereby weakening the electrical property of the lithium battery.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a coiling article forming method of coiling problem is provided to improve.

The utility model provides a technical scheme that above-mentioned technical problem adopted does: the positive plate assembly comprises a positive plate and a positive pole lug, wherein the positive pole lug is welded on one side surface of the positive plate, so that the positive pole lug forms a welding section connected with the positive plate and an excess section used for connecting a sealing body;

the welding section of the positive pole lug and the corresponding positive pole piece part are formed into a bent structure; the welding section of the positive pole lug and the positive pole piece at the corresponding position are provided with a front curved surface and a back curved surface which are concave inwards.

The utility model provides a further preferred technical scheme who above-mentioned technical problem adopted is: the neck part outside the welding section of the positive electrode lug is also formed into a bent structure, and the front end of the exceeding section is kept as an initial rectangular structure.

The utility model provides a further preferred technical scheme who above-mentioned technical problem adopted is: the inner end of the curved structure of the neck has a smaller curvature than the outer end.

The utility model discloses a another protection topic does: the winding product comprises the positive plate assembly, the diaphragm and the negative plate, and the positive plate assembly, the diaphragm and the negative plate are sequentially superposed and then wound; the bending curvature of the positive plate on which the positive pole tab is positioned after being wound is consistent with the bending curvature formed by punching the welding section.

The utility model provides a further preferred technical scheme who above-mentioned technical problem adopted is: and winding the positive plate on a winding mandrel in the inward direction.

The utility model discloses a another protection topic does: the stamping forming equipment comprises a stamping head capable of moving up and down and a fixed base with a stamping groove, wherein the stamping groove is provided with an arc-shaped bottom surface; the punching head comprises an arc pressing surface matched with the arc bottom surface, and the curvature of the arc bottom surface is consistent with that of the arc pressing surface.

The stamping forming equipment comprises a stamping head capable of moving up and down and a fixed base with a stamping groove, wherein the stamping groove is provided with an arc-shaped bottom surface; the punching head comprises an arc pressing surface matched with the arc bottom surface, and the curvature of the arc bottom surface is consistent with that of the arc pressing surface.

The utility model provides a further preferred technical scheme who above-mentioned technical problem adopted is: the fixed base comprises a placing plane used for flatly laying the positive plate, and the stamping groove is inwards concave to the placing plane.

The utility model provides a further preferred technical scheme who above-mentioned technical problem adopted is: the stamping groove extends along the width direction of the fixed base, and the edge of the stamping groove extends to two side faces of the fixed base in the width direction.

The utility model provides a further preferred technical scheme who above-mentioned technical problem adopted is: the punching head is of a plate-shaped structure, the punching groove is of a strip shape, and the lengths of the punching head and the punching groove are consistent with the length of a bent structure to be punched of the positive pole lug.

The utility model provides a further preferred technical scheme who above-mentioned technical problem adopted is: the length of the fixing base is equal to or greater than that of the positive plate, and the width of the fixing base is smaller than the total width of the positive plate assembly but greater than that of the positive plate.

Compared with the prior art, the utility model has the advantages that the welding section of the positive pole ear is transversely bent and shaped, so that the two sides of the welding section are in arc surface contact with the positive pole piece, the damage of the edge part of the positive pole ear to the positive pole piece during winding is prevented, and the positive pole piece is prevented from being punctured or cracked; after the winding forming, the fitting degree of the positive plates on the two surfaces of the positive pole lug is better, the roundness of the whole winding product is better, the subsequent assembly of the battery core and the battery shell is more facilitated, the supporting gap of the winding product after winding on the edge of the positive pole lug is smaller, the pole pieces on the two sides are in contact with each other more closely, and the electrical property of the lithium battery is improved.

Drawings

The present invention will be described in further detail below with reference to the drawings and preferred embodiments, but those skilled in the art will appreciate that the drawings are only drawn for the purpose of explaining the preferred embodiments, and therefore should not be taken as limiting the scope of the present invention. Furthermore, unless specifically stated otherwise, the drawings are merely schematic representations based on conceptual representations of elements or structures depicted and may contain exaggerated displays and are not necessarily drawn to scale.

Fig. 1 is a schematic view of a battery wound product according to the background art of the present invention;

fig. 2 is a schematic view of the connection between the positive plate and the positive tab in the background art of the present invention;

fig. 3 is a schematic view of a wound electrical core according to a first embodiment of the present invention;

fig. 4 is a schematic view of a first step of a wound product molding method according to a first embodiment of the present invention;

fig. 5 is a schematic view of a second step of the wound product molding method according to the first embodiment of the present invention;

fig. 6 is a schematic diagram of forming a positive electrode sheet assembly in two steps according to a first embodiment of the present invention;

fig. 7 is a first schematic view illustrating a stamping process of a stamping forming apparatus according to a first embodiment of the present invention;

fig. 8 is a second schematic view of a stamping process of the stamping and forming apparatus according to the first embodiment of the present invention;

fig. 9 is a schematic view of the positive electrode tab after being subjected to the punch forming according to the first embodiment of the present invention;

fig. 10 is a cross-sectional view of the front end of the protruding section of the positive electrode tab according to the first embodiment of the present invention;

fig. 11 is a cross-sectional view of the neck of the protruding section of the positive electrode tab according to the first embodiment of the present invention;

fig. 12 is a cross-sectional view of a welding section of a positive electrode tab according to a first embodiment of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Those skilled in the art will appreciate that the description is illustrative only, and is not to be construed as limiting the scope of the invention.

It should be noted that: like reference numerals refer to like items in the following figures, and thus, once an item is defined in one figure, it may not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "upper" and "lower" are used for indicating the position or positional relationship based on the position or positional relationship shown in the drawings, or the position or positional relationship which is usually placed when the product of the present invention is used, and are only for convenience of describing the present invention and simplifying the description, but not for indicating or implying that the indicated device or element must have a specific position, be constructed and operated in a specific position, and thus should not be construed as limiting the present invention.

The winding type battery comprises a positive electrode shell, a negative electrode shell and a battery cell, wherein the battery cell comprises a diaphragm 11, a positive electrode sheet 9 and a negative electrode sheet 10 as shown in fig. 3. The battery cell is a winding product. The positive plate 9, the diaphragm 11 and the negative plate 10 are sequentially stacked to form a battery core to be wound, and the diaphragm 11 is arranged between the positive plate 9 and the negative plate 10 to separate the two plates; the cell to be wound is wound on a winding mandrel 16 in the direction in which the positive electrode sheet 9 faces inward, so as to form a wound cell. The positive plate 9 is welded with a positive pole tab 3, and the positive pole tab 3 is connected with a positive pole terminal so as to lead current out of the battery core to the battery shell.

The positive electrode plate 9 and the negative electrode plate 10 are formed by mixing corresponding active materials, conductive agents, binders and necessary dispersing agents and then tabletting or coating. Preferably, the active material of the positive electrode is lithium cobaltate, and the active material of the negative electrode is a silicon carbon material.

In the embodiment, a winding product forming method is provided, and the method can solve the problem that the positive pole tab 3 damages the positive pole piece 9 in the winding and using processes. The method for forming the wound product will be specifically explained below with reference to the drawings, and the method at least includes the following steps.

As shown in fig. 4, step one: a positive electrode tab 3 having a rectangular cross section is selected and welded to one side surface of the positive electrode tab 9 to produce a positive electrode tab assembly.

Preferably, the positive electrode tab 9 has a rectangular sheet structure, the positive electrode tab 3 is provided on one side of the long side of the positive electrode tab 9, and the positive electrode tab 3 extends in a direction perpendicular to the long side of the positive electrode tab 9.

The inner end of the positive pole tab 3 is positioned in the positive pole piece 9, and the outer end of the positive pole tab exceeds the positive pole piece 9. Therefore, the positive electrode tab 3 is divided into a welding segment 1 connected to the positive electrode sheet 9 and an excess segment 2 for connecting the sealing member.

As shown in fig. 5-8, step two: stamping a welding section 1 on a positive pole lug 3 of the positive pole piece assembly by using a stamping process, so that the welding section 1 of the positive pole lug 3 and a corresponding positive pole piece 9 part are formed into a bent structure; the welding section 1 of the positive pole lug 3 and the positive pole piece 9 at the corresponding position are provided with a front curved surface and a back curved surface which are concave inwards.

It should be noted that the forward curved surface and the backward curved surface are straight cylindrical surfaces, a generatrix of the straight cylindrical surfaces is perpendicular to the long side of the positive electrode tab 9, and a collimation line of the straight cylindrical surfaces is parallel to the long side of the positive electrode tab 9.

It should be noted that the curvature of the directrix of the straight cylindrical surface should be equivalent to the curvature of the cell at the position of the positive electrode tab 3 after winding the cell.

Step three: the positive plate assembly, the diaphragm 11 and the negative plate 10 which are punched in the step 2) are sequentially superposed and then are subjected to winding process treatment; the bending curvature of the positive plate 9 where the positive pole tab 3 is located after winding is kept consistent with the bending curvature formed by punching the welding section 1, and finally a wound product is formed.

As shown in fig. 3, the welding section 1 of the positive electrode tab 3 is transversely bent and shaped in the winding process, so that both sides of the welding section are in arc contact with the positive electrode plate 9, the first edge portion 12 and the second edge portion 13 of the positive electrode tab 3 are prevented from damaging the positive electrode plate 9 during winding, and the positive electrode plate 9 is prevented from being punctured or cracked.

Further, when the positive electrode sheet 9 is bent in the lateral direction, the strength of the portion is enhanced, and the tab collision deformation caused in the subsequent production process can be prevented.

And after winding forming, the fitting degree of the positive plates 9 on the two surfaces of the positive electrode tab 3 is better, and the roundness of the whole wound product is better, so that the subsequent assembly of the battery cell and the battery shell is more facilitated. And the wrinkling phenomenon of the positive plate 9 can be reduced, the falling of an active material layer of the positive plate can be reduced, and the attenuation speed of the cyclic utilization of the battery cell is reduced.

In addition, the bending curvature of the positive plate 9 where the positive electrode tab 3 is located after winding is consistent with the bending curvature formed by stamping the welding section 1, so that the first supporting gap 14 and the second supporting gap 15 of the wound battery cell at the edge of the positive electrode tab 3 are smaller, the positive plate 9 is in closer contact with the negative plate 10, and the electrical performance of the lithium battery is improved.

As shown in fig. 9 to 12, it is preferable that the neck portion M outside the welded section 1 of the positive electrode tab 3 is also formed in a bent-like structure, leaving the front end Y of the excess section 2 in an initial rectangular structure. More preferably, the inner end of the curved structure of the neck M has a smaller curvature than the outer end and assumes a gradually flattened position from the inside towards the outside. So make welding section 1 of anodal utmost point ear 3 with surpass the higher joint strength that keeps between the section 2, avoid welding section 1 crooked to lead to whole anodal utmost point ear 3's mechanical strength to receive the damage.

As shown in fig. 5, 7, and 8, as one embodiment of the press forming apparatus used in step 2), the press forming apparatus includes a press head 6 and a fixed base 7 that can move up and down.

The fixing base 7 comprises a placing plane 4 capable of being used for flatly laying the positive plates 9 and a stamping groove 5 which is concave in the placing plane 4, the stamping groove 5 extends along the width direction of the fixing base 7, and the edge of the stamping groove 5 extends to two side faces of the fixing base 7 in the width direction.

Preferably, the stamping head 6 is of a plate-shaped structure, the stamping groove 5 is of a strip shape, and the lengths of the stamping head 6 and the stamping groove 5 are consistent with the length of the bent structure to be stamped of the positive electrode tab 3.

Preferably, the length of the fixing base 7 is equal to or greater than the length of the positive electrode tab 9, and the width of the fixing base 7 is smaller than the total width of the positive electrode tab assembly, but greater than the width of the positive electrode tab 9.

Furthermore, the punching groove 5 has an arc-shaped bottom surface 51, which includes a straight cylindrical surface matching with the curved back surface of the positive electrode tab 9 after punch forming and a curved surface matching with the curved structure of the neck M of the positive electrode tab 3 after punch forming.

The punch head 6 comprises an arcuate pressing surface 61 which is matched with the arcuate bottom surface, the curvature of the arcuate bottom surface corresponding to the curvature of the arcuate pressing surface.

In the processing process, the positive plate 9 is laid on the laying plane 4 along the length direction of the fixed base 7, so that the long edge of the positive plate 9 is perpendicular to the stamping groove 5. The projection position of the positive pole lug 3 just falls on the stamping groove 5, and the central axis of the positive pole lug 3 is aligned with the central axis of the stamping groove 5. The punching head 6 is pressed down on the positive pole tab 3, so that the welding part and the neck part M of the positive pole tab 3 are bent.

The above description is made in detail on the winding product forming method, the positive plate assembly, the winding product and the punch forming equipment provided by the present invention, and of course, the above processing method for the positive electrode tab can also be used for the negative electrode tab.

The principles and embodiments of the present invention have been explained herein using specific examples, and the above descriptions of the embodiments are only used to help understand the present invention and the core ideas. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.

Claims

1. The positive plate assembly is characterized by comprising a positive plate and a positive pole lug, wherein the positive pole lug is welded on one side surface of the positive plate, so that the positive pole lug forms a welding section connected with the positive plate and an excess section used for connecting a sealing body; the welding section of the positive pole lug and the corresponding positive pole piece part are formed into a bent structure; the welding section of the positive pole lug and the positive pole piece at the corresponding position are provided with a front curved surface and a back curved surface which are concave inwards.

2. The positive plate assembly according to claim 1, wherein the neck portion of the positive tab except the welded portion is also formed into a curved structure, leaving the front end of the excess portion in an initial rectangular structure.

3. The positive electrode tab assembly of claim 2, wherein the curved configuration of the neck has an inner end with a lesser curvature than an outer end.

4. A wound product, comprising the positive electrode sheet assembly, the separator and the negative electrode sheet according to any one of claims 1 to 2, wherein the positive electrode sheet assembly, the separator and the negative electrode sheet are sequentially stacked and then wound; the bending curvature of the positive plate on which the positive pole tab is positioned after being wound is consistent with the bending curvature formed by punching the welding section.

5. The wound product according to claim 4, wherein the positive electrode sheet is wound on a winding mandrel in an inward direction.

6. The stamping forming equipment is characterized by comprising a stamping head capable of moving up and down and a fixed base with a stamping groove, wherein the stamping groove is provided with an arc-shaped bottom surface; the punching head comprises an arc pressing surface matched with the arc bottom surface, and the curvature of the arc bottom surface is consistent with that of the arc pressing surface.

7. The apparatus of claim 6, wherein said mounting base includes a planar surface for laying said positive plates, and said stamping groove is recessed within said planar surface.

8. The press-forming apparatus according to claim 7, wherein the punching groove extends in a width direction of the fixed base, and edges of the punching groove extend to both side surfaces in the width direction of the fixed base.

9. The punch forming device according to claim 6, wherein the punch is of a plate-shaped structure, the punch groove is of a strip shape, and the lengths of the punch and the punch groove are consistent with the length of the curved structure to be punched of the positive electrode tab.

10. The press-forming apparatus according to claim 8, wherein the fixing base has a length equal to or greater than that of the positive electrode tab, and the width of the fixing base is smaller than the total width of the positive electrode tab assembly but greater than that of the positive electrode tab.