CN109546077B

CN109546077B - Electrode pole piece, manufacturing method thereof and lithium ion battery

Info

Publication number: CN109546077B
Application number: CN201811600980.3A
Authority: CN
Inventors: 李佳佳; 史童男; 马小小
Original assignee: Svolt Energy Technology Co Ltd
Current assignee: Svolt Energy Technology Co Ltd
Priority date: 2018-12-26
Filing date: 2018-12-26
Publication date: 2021-09-21
Anticipated expiration: 2038-12-26
Also published as: CN109546077A

Abstract

The invention provides an electrode plate, a manufacturing method thereof and a lithium ion battery. The method for manufacturing the electrode plate comprises the following steps: intermittently coating a discharging area and an empty foil area on the surface of the foil, wherein the discharging area and the empty foil area are arranged at intervals along the longitudinal direction; rolling the intermittently coated pole rolls; cutting the rolled pole roll along the long edge of the electrode pole piece; and die cutting is carried out on the cut electrode roll to obtain an electrode lead of the electrode pole piece, and the die cutting is along the short edge of the electrode pole piece. According to the manufacturing method provided by the invention, the coating process adopts intermittent coating, and the empty foil area is formed between the two longitudinally-distributed material areas, so that the deformation of the die-cut electrode lead is avoided, and the die-cut edge occupation ratio is small, so that the burrs can be better controlled, and the yield of the manufactured electrode pole piece is higher.

Description

Electrode pole piece, manufacturing method thereof and lithium ion battery

Technical Field

The invention relates to the technical field of lithium ion battery manufacturing, in particular to an electrode plate, a manufacturing method thereof and a lithium ion battery.

Background

With the development of new energy automobiles, lithium ion batteries are widely used in energy storage devices of electric automobiles. With this, there is a problem that the size of the battery and the structural design thereof become various. Batteries can be classified into square batteries, pouch batteries, and cylindrical batteries according to their outer packages. The structure according to inside electric core can be divided into two kinds of coiling formula and lamination formula, and wherein, lamination formula electric core is by wide application in square-shell battery and laminate polymer battery.

The current cell designs tend to be large size, high aspect ratio designs, so the lamination process is more suitable for the production of such cells. The production steps of the existing battery pole piece mainly comprise the working procedures of homogenizing, coating, rolling, slitting, die cutting, winding/laminating, assembling, forming and the like. In the slitting process, because a transverse gap is not formed between the two slitting cutters, the pole piece is not torn, and burrs are not easy to generate in the normal production process; in the die cutting process, a transverse gap exists between the two die cutting cutters, so that the foil is easily torn and rolled to form burrs. The cutting device is not easy to generate burrs in the cutting process, so that the burrs are easy to control, and the burrs are easy to generate in the die cutting process, so that the burrs are not easy to control. Pole pieces produced when burrs are uncontrolled can puncture the separator due to excessive burrs, shorting the cell. And compared with the lamination process, the winding process is mainly slitting, and the lamination needs die cutting, so the burr of the winding process is easier to control than the lamination process.

Therefore, the lamination process of the electrode pole piece at the present stage still needs to be improved.

Disclosure of Invention

The present invention has been completed based on the following findings of the inventors:

in the research process, the inventor finds that, referring to fig. 1, the existing coating process of the electrode plate in the laminated battery adopts continuous coating, firstly coats the slurry on the foil 100 (step S100, not shown in the figure), then rolls (step S200, not shown in the figure), and finally cuts (step S300) and die-cuts (step S400) the electrode plate into the electrode plate 400 with the required size. Wherein the rolling machine of the rolling step has upper and lower two rollers with a certain gap therebetween, and the material region 200 is rolled to a designated thickness after passing through the rolling machine. However, since the thickness of the stock region 200 is much greater than the thickness of the edges of the foils 100, the foils 100 of the stock region 200 are easily deformed in the longitudinal direction during the rolling process, and the thickness of the foils 100 of the empty foil region 200 is smaller than the gap between the upper and lower rollers and is not expanded. Therefore, after rolling, the length of the material region 100 is greater than that of the empty foil region 200, which easily causes deformation of the empty foil region 200, and thus causes deformation of the cut electrode lead 420, and finally causes poor welding of the electrode lead 420 during welding, thereby affecting the yield of the electrode sheet 400.

The inventor of the invention has conducted extensive research and provides a novel coating process, namely, intermittent coating is adopted, and a blank foil area is arranged between two longitudinally arranged material areas, so that longitudinal extension of the material areas after rolling does not affect the blank foil area, and deformation of a die-cut electrode lead is avoided. And the material is distinguished and cut into the long side of the electrode plate, and the die-cut is the short side of the electrode plate, so that the die-cut side has a small occupation ratio, burrs can be better controlled, and the manufactured electrode plate has higher yield and is not easy to cause safety problems.

In view of the above, an object of the present invention is to provide a method for manufacturing an electrode plate, which has better control of the die-cut burr and higher yield.

In a first aspect of the invention, a method of making an electrode sheet is provided.

According to an embodiment of the invention, the method comprises: intermittently coating a discharging area and an empty foil area on the surface of the foil, wherein the discharging area and the empty foil area are arranged at intervals along the longitudinal direction; rolling the intermittently coated pole roll; cutting the rolled pole piece roll along the long edge of the electrode pole piece; and die cutting is carried out on the cut pole roll to obtain an electrode lead of the electrode pole piece, and the die cutting is along the short side of the electrode pole piece.

The inventor finds that by adopting the method for manufacturing the electrode plate, the coating process adopts intermittent coating, and the empty foil area is formed between the two longitudinally-arranged material areas, so that the longitudinal extension of the material areas after rolling does not influence the empty foil area, and the deformation of the electrode lead cut by a die is avoided. And the material is distinguished and cut out to be the long side of electrode sheet, and the mould is cut out to be the minor face of electrode sheet, and such mould side cut accounts for than little to can control the burr better, and then make the yields of the electrode sheet of making higher, be difficult to cause the security problem.

In addition, the manufacturing method according to the above embodiment of the present invention may further have the following additional technical features:

according to the embodiment of the invention, the length of the material area is the length of the electrode pole piece, and the width of the material area is integral multiple of the width of the electrode pole piece.

According to an embodiment of the invention, the width of the material area is twice the width of the electrode sheet.

According to an embodiment of the present invention, the minimum unit width of the intermittent coating is a width of the electrode tab.

According to an embodiment of the invention, the lateral distance between the edge of the material area and the edge of the foil is not less than 3 mm.

According to the embodiment of the invention, four corners of the die-cut electrode pole piece are arc-shaped.

In a second aspect of the invention, the invention provides an electrode plate.

According to the embodiment of the invention, the electrode pole piece is manufactured by the method.

The inventor finds that the burrs die-cut on the electrode plate in the embodiment of the invention are better controlled, the electrode lead is not deformed, and the yield is higher, so that the poor welding is less when the electrode lead is welded, the probability that the burrs of the electrode plate pierce the diaphragm is reduced, the service life of the lithium ion battery is longer, and the safety performance is better. It will be understood by those skilled in the art that the features and advantages described above with respect to the method of making an electrode pad are still applicable to the electrode pad and will not be described herein again.

In addition, the electrode sheet according to the above embodiment of the present invention may further have the following additional technical features:

according to the embodiment of the invention, four corners of the electrode pole piece are convex arcs.

According to an embodiment of the present invention, the electrode leads of the electrode pad are disposed at a middle position of the short side of the electrode pad, or disposed at both side portions of the short side of the electrode pad.

In a third aspect of the invention, a lithium ion battery is presented.

According to an embodiment of the present invention, the lithium ion battery includes a positive electrode plate, a separator, and a negative electrode plate, wherein at least one of the positive electrode plate and the negative electrode plate is the electrode plate.

The inventor finds that the lithium ion battery provided by the embodiment of the invention has the advantages that the burrs of the positive pole piece or the negative pole piece are less, the electrode lead is not deformed, and the yield is higher, so that the lithium ion battery has longer service life and better safety performance. It will be understood by those skilled in the art that the features and advantages described above with respect to the electrode pads are still applicable to the lithium ion battery and will not be described in detail herein.

Additional aspects and advantages of the invention 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 invention.

Drawings

The foregoing aspects of the invention are explained in the description of the embodiments with reference to the following drawings, in which:

FIG. 1 is a flow chart of a prior art electrode tab fabrication process;

FIG. 2 is a schematic flow chart of a method for manufacturing an electrode sheet according to an embodiment of the present invention;

FIG. 3 is a flow chart of a process for making an electrode pad of one embodiment of the present invention;

FIG. 4 is an enlarged partial view of one of the four corners of an electrode sheet of the prior art;

FIG. 5 is an enlarged partial view of one of the four corners of an electrode pad of one embodiment of the present invention;

fig. 6 is a schematic diagram of the arrangement positions of the electrode leads of the electrode sheet according to three embodiments of the present invention.

Reference numerals

100 foil

200 material area

300 empty foil area

400 electrode pole piece

410 electrode lead

420 material layer

Detailed Description

The following examples of the present invention are described in detail, and it will be understood by those skilled in the art that the following examples are intended to illustrate the present invention, but should not be construed as limiting the present invention. Unless otherwise indicated, specific techniques or conditions are not explicitly described in the following examples, and those skilled in the art may follow techniques or conditions commonly employed in the art or in accordance with the product specifications.

In one aspect of the invention, a method of making an electrode sheet is provided.

According to an embodiment of the present invention, referring to fig. 2, the manufacturing method includes:

s100: and intermittently coating a discharging area and an empty foil area on the surface of the foil.

In this step, referring to fig. 3, the discharging regions 200 and the empty foil regions 300 are intermittently coated on the surface of the foil sheet 100, and the discharging regions 200 and the empty foil regions 300 are alternately arranged in the longitudinal direction.

The inventor of the present invention has found through research that in the existing coating process, the electrode leads 410 are disposed at two lateral edges of the material area 200, the material area 200 is easily extended and lengthened in the longitudinal direction in the subsequent rolling process, and the empty foil area 300 is not extended and lengthened due to not contacting the rolling roller, so that a length difference occurs between the empty foil area 300 and the material area 200, and the empty foil area 300 is deformed, so that the pole piece lead cut by a subsequent die is easily deformed, and further poor welding is easily generated when the pole piece lead is welded. Therefore, the inventors formed the empty foil region 300 between two longitudinally arranged material regions 200, so that the empty foil region 200 is not affected even if the subsequent rolled material regions 200 extend in the longitudinal direction, thereby effectively preventing the electrode leads 410 cut by the subsequent die from being deformed.

According to an embodiment of the present invention, the length of the material region 200 may be the length of the electrode tab 400, and meanwhile, the width of the material region 200 may be an integral multiple of the width of the electrode tab 400. It should be noted that, herein, the "length" of the material section 200 refers to the dimension in the longitudinal direction, and the "width" of the material section 200 refers to the dimension in the transverse direction.

The inventor of the invention discovers through research that in the existing coating process, the short edge of the electrode pole piece is used as a sub-trimming edge, and the long edge of the electrode pole piece is used as a die trimming edge, so that the die trimming edge of the produced pole piece is large in proportion, and the control of burrs is difficult. Therefore, the inventor adopts the gap type coating process, the length of the coated material area 200 is the length of the electrode pole piece, the width of the coated material area 200 is integral multiple of the width of the electrode pole piece, in this way, the long side of the electrode pole piece is cut, the short side of the pole piece is cut by die, the die cutting ratio is small, and burrs are easier to control than the existing process.

In some embodiments of the present invention, the width of the material region 200 may be twice the width of the electrode tab 400. The inventor of the invention discovers, through research, that the coating width in the existing coating process is twice of the length of the electrode pole piece, the electrode pole piece is manufactured by cutting the electrode pole piece into a pole roll with single pole piece length and then die cutting, and the process not only needs to adjust the coating width but also needs to manufacture a die cutting tool again when the size of the electrode pole piece changes. Therefore, the inventor sets the length of the material area 200 coated in the gap to be the length of the electrode plate 400, so that the length of the coating can be adjusted by adjusting the parameters of the equipment, the length of the manufactured electrode plate 400 can be adjusted, and the width of the electrode plate 400 can be controlled by adjusting the slitting size of the slitting equipment, so that the production of the electrode plates with different sizes can be quickly converted under the condition of not replacing any equipment and tooling, and the adjustment period is shorter and the investment is less.

In other embodiments of the present invention, the minimum unit width of the intermittent coating may be the width of the electrode tab 400. The inventor of the present invention has found through research that, for a foil 100 with a fixed width, the greater the minimum unit width of coating, the poorer the compatibility of the foil, and the more likely a large amount of useless waste materials will appear; the "minimum unit width of coating" specifically means the minimum width of the coated material region 200, that is, the minimum width of the material region 200 is the width of the electrode sheet 400. The minimum unit width of coating in the prior art is the length of the electrode plate plus the length of the lead of the electrode plate, but the minimum unit of coating in the invention is the width of the electrode plate, so that the coating provided by the invention has better compatibility with foil and higher utilization rate of the foil.

According to the embodiment of the invention, the transverse distance from the edge of the material area 200 to the edge of the foil 100 is not less than 3mm, so that the alignment degree of the material areas 200 on the two sides of the foil 100 is ensured, and the edge area can be cut off in the subsequent cutting process without affecting the dimensional accuracy of the cut electrode pole piece 400.

S200: and rolling the pole roll after intermittent coating.

In this step, the rolling is continued on the pole roll of the intermittent coating number in step S100, and thus, since the empty foil region 300 is formed between the two longitudinally arranged material regions 200, the empty foil region 200 is not affected by the longitudinal extension of the rolled material regions 200, and thus the deformation of the electrode lead 410 cut by the subsequent die can be effectively avoided.

S300: and cutting the rolled pole rolls.

In this step, the rolled electrode roll of step S200 is slit, and referring to fig. 3, the slit is along the long side of the electrode sheet 400, so the slit range is wider, and the generated burrs are easier to control, so that the final manufactured electrode sheet has fewer burrs.

S400: and die cutting is carried out on the slit electrode roll to obtain an electrode lead of the electrode pole piece.

In this step, the pole roll slit in step S300 is continuously die-cut to obtain the electrode lead 410 of the electrode tab 400, and the die-cut is along the short side of the electrode tab 400.

In some embodiments of the present invention, the four corners of the die-cut electrode sheet 400 may be convex arcs. The inventor of the present invention finds, through research, that, in the electrode sheet with a high aspect ratio produced by the prior art, referring to fig. 4 (fig. 4 is a partial enlarged view of an area a in fig. 1), four corners are processed to be concave arcs, so that the cut-off area of the produced electrode sheet is large, the capacity loss is large, and the concave chamfer design makes the electrode sheet chamfer sharp, so that the electrode sheet is easy to pierce through a diaphragm to generate a short circuit, thereby causing a safety risk. Therefore, the inventor designs the four corners to be convex arcs, and referring to fig. 5 (fig. 5 is a partial enlarged view of the area B in fig. 3), the loss of the pole piece area can be reduced, and the capacity loss can be reduced, and the convex arcs have no sharp chamfer, so that the risk of short circuit caused by the chamfer penetrating through the diaphragm can be avoided.

According to the embodiment of the present invention, the method for manufacturing an electrode plate may further include other steps, such as homogenizing, winding or laminating, assembling, etc., in addition to the above steps S100, S200, S300 and S400, and those skilled in the art may make corresponding additions and adjustments according to the specific design of the electrode plate, which is not described herein again.

In summary, according to the embodiments of the present invention, the present invention provides a method for manufacturing an electrode sheet, wherein the coating process employs intermittent coating, and the empty foil region is formed between two longitudinally arranged material regions, so that the longitudinal extension of the material regions after being rolled does not affect the empty foil region, thereby preventing the deformation of the electrode lead cut by the die. And the material is distinguished and cut out to be the long side of electrode sheet, and the mould is cut out to be the minor face of electrode sheet, and such mould side cut accounts for than little to can control the burr better, and then make the yields of the electrode sheet of making higher.

In another aspect of the invention, the invention provides an electrode plate. According to the embodiment of the invention, the electrode pole piece is manufactured by the method.

According to the embodiment of the present invention, the specific type of the battery pole piece is not particularly limited, specifically, for example, the positive pole piece or the negative pole piece, and the like, and those skilled in the art can correspondingly select the type according to the specific function of the electrode pole piece, and details are not repeated herein.

According to the embodiment of the invention, referring to fig. 5, four corners of the electrode plate can be convex arcs, so that the loss of the area of the electrode plate can be reduced, the capacity loss can be reduced, and the convex arcs have no sharp chamfer, so that the short circuit risk caused by the fact that the chamfer pierces the diaphragm can be avoided.

In some embodiments of the present invention, referring to fig. 6 (b), the electrode leads of the electrode pad may be disposed at a middle position of the short side of the electrode pad, so that the shape of the die-cut electrode leads is more symmetrical. In other embodiments of the present invention, referring to (a) and (c) of fig. 6, the electrode leads of the electrode plate may also be disposed at two side portions of the short side of the electrode plate, so that the electrode lead of the positive electrode plate may be disposed at the left side, and the electrode lead of the negative electrode plate may be disposed at the right side, which is beneficial to convenience in cell welding.

In summary, according to the embodiments of the present invention, the invention provides an electrode sheet, in which the burrs die-cut are better controlled, the electrode lead is not deformed, and the yield is higher, so that the poor welding during welding the electrode lead is less, the probability that the burrs of the electrode sheet pierce the diaphragm is reduced, and further, the service life of the lithium ion battery is longer, and the safety performance is better. It will be understood by those skilled in the art that the features and advantages described above with respect to the method of making an electrode pad are still applicable to the electrode pad and will not be described herein again.

In another aspect of the invention, a lithium ion battery is provided.

According to the embodiment of the invention, the lithium ion battery comprises a positive pole piece, a diaphragm and a negative pole piece, wherein at least one of the positive pole piece and the negative pole piece is the electrode pole piece.

According to the embodiment of the present invention, the specific type of the lithium ion battery is not particularly limited, and specifically, for example, a liquid lithium ion battery or a polymer lithium ion battery, etc., and those skilled in the art can select the type according to the specific use requirement and the actual use environment of the lithium ion battery. It should be noted that the lithium ion battery includes other necessary components and structures besides the positive electrode plate, the separator, and the negative electrode plate, taking a liquid lithium ion battery as an example, specifically, such as an electrolyte, a housing, a circuit, and the like, and those skilled in the art can design and supplement the lithium ion battery according to the specific type of the lithium ion battery, and details are not described herein.

In summary, according to the embodiments of the present invention, the present invention provides a lithium ion battery, which has fewer burrs on a positive electrode plate or a negative electrode plate, no deformation of an electrode lead, and a higher yield, so that the lithium ion battery has a longer service life and a better safety performance. It will be understood by those skilled in the art that the features and advantages described above with respect to the electrode pads are still applicable to the lithium ion battery and will not be described in detail herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A method of making an electrode sheet comprising:

intermittently coating a discharging area and an empty foil area on the surface of the foil, wherein the discharging area and the empty foil area are arranged at intervals along the longitudinal direction;

rolling the intermittently coated pole roll;

cutting the rolled pole piece roll along the long edge of the electrode pole piece;

die cutting is carried out on the cut pole roll to obtain an electrode lead of the electrode pole piece, and the die cutting is carried out along the short side of the electrode pole piece;

the length of the material area is the length of the electrode pole piece, and the width of the material area is integral multiple of the width of the electrode pole piece;

the minimum unit width of the intermittent coating is the width of the electrode pole piece;

the transverse distance between the edge of the material area and the edge of the foil is not less than 3 mm;

and four corners of the die-cut electrode plate are arc-shaped.

2. The method of claim 1, wherein the width of the material zone is twice the width of the electrode sheet.

3. An electrode sheet produced by the method of claim 1 or 2.

4. The electrode tab according to claim 3, wherein the electrode lead of the electrode tab is disposed at a middle position of the short side of the electrode tab or at both side portions of the short side of the electrode tab.

5. A lithium ion battery, characterized by comprising a positive electrode plate, a diaphragm and a negative electrode plate, wherein at least one of the positive electrode plate and the negative electrode plate is the electrode plate of claim 3 or 4.