CN204905336U - Electrode pole piece and adopt electric core of this pole piece - Google Patents

Abstract

The present application relates to the field of energy storage devices, in particular to an electrode pole piece and an electric core using the pole piece. In the area coated with the active material layer, and corresponding to the positions of the tabs of the positive and/or negative electrodes, the size of the slot is not smaller than the corresponding size of the connection area between the corresponding tab and the uncoated area . The cell includes a positive pole piece and/or a negative pole piece composed of a separator and an electrode pole piece. The positive pole piece, the negative pole piece and the separator form a winding battery core. The total number of slots on the positive pole piece and the negative pole piece is Two, and the positions of the two slots correspond to the positions of the tabs of the positive pole and the negative pole one by one. In the cell provided by the present application, the protruding part of the tab welding area can be absorbed by the slot, thereby reducing the influence of the welding tab on the thickness of the cell and increasing the volumetric energy density of the battery.

Description

Electrode pole piece and cell using the pole piece

technical field

The present application relates to the field of energy storage devices, in particular to an electrode pole piece and a cell using the pole piece.

Background technique

In the related art, both the positive pole piece and the negative pole piece of the lithium-ion battery include a current collector, an active material layer and tabs, and the active material layer is coated on the surface of the current collector, and at both ends of the current collector in the length direction There is an uncoated area, and the tab welding is in an uncoated area.

Due to the existence of tabs, after the battery core is wound by this process, the thickest part of the battery core is usually where the tabs are welded, thus reducing the volumetric energy density of the battery.

Utility model content

The present application provides an electrode pole piece and a battery cell using the pole piece, which can reduce the problem of thickening of the battery cell caused by welding tabs, and improve the volumetric energy density of the battery.

The first aspect of the present application provides an electrode sheet, including a current collector, an active material layer, and a tab, the active material layer is coated on the surface of the current collector, and in the length direction of the current collector An uncoated area is left at both ends, and the tab is arranged in one of the uncoated areas, and also includes a slot, and the slot is opened in the area where the current collector is coated with the active material layer Inside, and when the electrode pole piece is wound to form a battery core, the position of the slot corresponds to the position of the tab of the positive electrode and/or negative electrode one by one, and the slot is closed on three sides and open on one side configuration, including a wide side and two opposite long sides, the size of the long side and the size of the wide side are not smaller than the corresponding connection area between the tab and the uncoated area corresponding size.

Preferably, both sides of the slot are provided with insulating glue, and the insulating glue is at least bonded to the outer sides of the two long sides of the slot, and spans the slot along the extending direction of the wide side bit.

Preferably, the insulating glue completely covers the slot, and is bonded to the outer sides of the two long sides and one of the wide sides of the slot.

Preferably, both sides of the current collector are coated with the active material layer, and the active material layer on one side of the current collector is connected to the active material layer on the other side of the current collector. The projections of the active material layer on the current collector overlap,

The slots are opened in the overlapping area, and the slots are also located in the areas of the active material layer on both sides of the current collector.

Preferably, both sides of the current collector are coated with the active material layer, and the uncoated area on one side of the current collector is connected to the active material layer on the other side of the current collector. The projections of the active material layer on the current collector overlap,

The slots are opened in the overlapping area, and the slots are located in the area of the active material layer on one side of the current collector and in the uncoated area on the other side of the current collector.

The second aspect of the present application provides an electric core, including a separator and a positive pole piece and/or a negative pole piece composed of the above-mentioned electrode pole piece, the positive pole piece, the negative pole piece and the The separator forms a winding cell, the sum of the number of slots on the positive pole piece and the negative pole piece is two, and the positions of the two slots are the same as the positions of the tabs of the positive pole and the negative pole. One to one correspondence.

Preferably, both of the slots are arranged on the positive pole piece.

Preferably, at least one of the slots is provided on the negative pole piece, and the area on the positive pole piece opposite to the slot provided on the negative pole piece through a layer of the separator is not exposed the active material layer.

Preferably, the active material layer is not coated on a region of the positive electrode sheet opposite to the slot provided on the negative electrode sheet via a layer of the separator.

Preferably, the outer side of the active material layer is covered with a shielding layer in the area opposite to the groove on the negative electrode sheet and the slot provided on the negative electrode sheet via a layer of the separator.

The technical solution provided by the application can achieve the following beneficial effects:

Since the cell provided by this application has a slot corresponding to the tab on the electrode pole piece, the protruding part of the tab welding area can be absorbed by the slot, thereby reducing the influence of the welding tab on the thickness of the cell. The volumetric energy density of the battery is improved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary only and are not restrictive of the application.

Description of drawings

Fig. 1 is the structural representation of the electrode pole piece provided by the embodiment of the present application;

Fig. 2 is a schematic structural view of the cell structure provided by the embodiment of the present application in which the slot is located on the positive pole piece;

Fig. 3 is a schematic structural view of the battery cell with the slot provided on the negative pole piece provided by the embodiment of the present application;

Fig. 4 is the electric core structural diagram of comparative example 1 provided by the embodiment of the present application;

Fig. 5 is the structural diagram of the electrode pad of Comparative Example 2 provided by the embodiment of the present application;

FIG. 6 is a schematic view of the cell structure of Comparative Example 2 provided by the embodiment of the present application.

Description of drawings:

1-electrode pole piece; 10-collector; 100-uncoated area; 12-active material layer; 14-tab; 16-slot; 18-insulating glue;

2- Isolation film.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description serve to explain the principles of the application.

Detailed ways

The present application will be described in further detail below through specific embodiments and in conjunction with the accompanying drawings. The "front", "rear", "left", "right", "upper" and "lower" mentioned in the text are all referred to the placement state of the electrode pole piece and the battery cell using the pole piece in the drawings.

As shown in FIG. 1 , Embodiment 1 of the present application provides an electrode sheet 1 , including a current collector 10 , an active material layer 12 , tabs 14 , slots 16 and insulating glue 18 . The active material layer 12 is coated on the surface of the current collector 10, most of the surfaces on both sides of the current collector 10 are coated with the active material layer 12, and an uncoated area 100 is left at both ends of the current collector 10 in the length direction. .

When winding to form an electric core, due to the different polarity of the electrode pole piece 1 and the different winding methods, the difference in the position of the active material layer 12 on both sides of the current collector 10 and other factors, the active material layer 12 on both sides of the current collector 10 Most of the projections on the current collector 10 overlap, but near the two ends, the starting position and the ending position of the active material layer 12 on both sides may be different, which may make the uncoated layer on one side of the current collector 10 The region 100 overlaps with the projection of the coating area of the active material layer 12 on the other side of the current collector 10 on the current collector 10 .

The slot 16 is opened in the area where the current collector 10 is coated with the active material layer 12, and when the electrode sheet 1 is wound to form a battery cell, the position of the slot 16 should be the same as the position of the tab 14 of the positive or negative pole. One to one correspondence. Generally, a part of the tab 14 is fixedly connected to one of the uncoated regions 100 by welding. The slot 16 is a configuration with three sides closed and one side open, including a wide side 160 and two opposite long sides 162, the size of the long side 162 and the size of the wide side 160 are not smaller than the corresponding tab 14 and The corresponding dimensions of the connection area of the uncoated area 100 .

Wherein, the slot 16 can be located in the area of the active material layer 12 on both sides of the current collector 10 at the same time, that is, in the area where the projections of the active material layers 12 on both sides overlap. But this way of opening the slot 16 is compared with the mode of not opening the slot 16 in the related art, because the slot 16 is opened in the overlapping area, it will cause the coating area of the active material layer 12 on both sides of the electrode pole piece 1 to be coated at the same time. The reduction has a greater impact on the total amount of active materials in the battery.

In this embodiment, the opening position of the slot 16 can also be in the area where the active material layer 12 on one side of the current collector 10 overlaps with the uncoated region 100 on the other side, so that the opening of the slot 16 only affects to the active material layer 12 on one side, so it has little influence on the total amount of active material in the cell.

During processing, the active material layer 12 can be coated on both sides of the current collector 10 in a general manner, and then die-cut at the corresponding position by die-cutting technology, and the active material layer 12 and the current collector 10 are punched off together to form grooves. Bit 16.

After punching the slot 16 formed, the strength of the electrode pole piece 1 there will be reduced, and the electrode pole piece 1 is likely to be broken during the process of winding to form the battery core. As shown in FIG. 1 , in this embodiment, in order to prevent the electrode sheet 1 from breaking when it is wound, insulating glue 18 is bonded to both sides of the slot 16 for structural reinforcement. The insulating glue 18 (such as green glue, etc.) spans the slot 16 along the extending direction of the wide side 160 and adheres to the outer sides of the two long sides 162 . In this way, the insulating glue 18 can provide a strong pulling force to prevent the electrode sheet from being broken by the slot 16 .

After opening the slot 16 on the electrode pole piece 1, not only will the pole piece be easily broken, but the exposed edge of the slot 16 may also cause a short circuit of the battery or lithium deposition. Therefore, in a more preferred manner, it is best to use insulating glue 18 to completely cover the slot 16 , and the insulating glue 18 is bonded to the outside of the two long sides 162 and one wide side 160 of the slot 16 . In this way, the slot 16 can be completely sealed by the insulating glue 18 on both sides, which reduces the risk of battery short circuit and lithium deposition.

The size of the bonding between the insulating glue 18 and the outside of the wide side 160 and the long side 162 of the slot 16 is basically about 5% of the corresponding width or length of the insulating glue 18 to ensure firm bonding.

As shown in FIG. 2 and FIG. 3 , Embodiment 2 of the present application provides a battery cell, including the electrode tab 1 and separator 2 provided in Embodiment 1. Among them, the electrode pole piece 1 provided in the first embodiment can be used as the positive pole piece of the battery cell, or can be used as the negative pole piece of the battery cell, or the positive pole and the negative pole piece of the battery core can use the electrode provided by the embodiment of the present application at the same time. The pole piece 1, the positive pole piece, the negative pole piece and the separator 2 constitute a winding cell. It should be noted that no matter how many electrode pads 1 provided by Embodiment 1 are used in the cell, the total number of slots 16 in the cell is two, and the positions of the two slots 16 must be aligned with the positive electrode. There is a one-to-one correspondence with the position of the tab 14 of the negative pole. The two slots 16 can be in the same layer of the battery core, or in different layers of the battery core. In this way, the protruding part of the welding area of the tab 14 can be absorbed by the slot 16, thereby reducing the influence of welding the tab 14 on the thickness of the battery cell, and increasing the volumetric energy density of the battery.

In the related art, in order to improve the performance of the battery cell, the amount of the negative electrode active material inside the battery cell generally requires an excess amount of the positive electrode active material. In this embodiment, the slot 16 can be set on the positive pole piece (see Figure 2), or it can be set on the negative pole piece (see Figure 3), but when the slot 16 is opened on the negative pole piece, the activity of the negative pole The amount of matter is reduced, thus reducing the performance of the cell. For this reason, in the present embodiment, corresponding to the groove position 16 that offers on the negative pole piece, process is carried out on the region opposite to this groove position 16 across a layer of separator 2 on the positive pole piece, so that the active material layer 12 is not exposed in this region. . This also reduces the amount of positive active material, thereby improving the performance of the battery. The non-exposed area of the active material layer 12 on the positive electrode sheet is preferably not smaller than the area of the insulating glue 18 covered by the slot 16 on the negative electrode sheet.

There are many ways to prevent the active material layer 12 from being exposed in the corresponding area of the positive electrode sheet, for example, laser or other mechanical cleaning methods are used to remove the active material in the corresponding area of the positive electrode sheet. It is also possible to use insulating glue 18 or the like to cover the active material in the corresponding area of the positive pole piece, so that the active material in this area cannot participate in the reaction.

However, no matter how it is handled, disposing the slot 16 on the negative electrode sheet will result in a simultaneous reduction of the positive active material and negative active material, greatly reducing the volumetric energy density of the cell. Therefore, it is the most preferred solution to arrange the two slots 16 on the positive electrode sheet.

The effect of the electrode pad provided by this application is verified through specific experiments as follows:

Experimental example 1

Taking the square battery of model 354798 (the thickness of the finished battery is 3.5 mm, the width is 47 mm, the length is 98 mm, and the number of winding layers is 10 layers) as an example, the preparation steps of the lithium-ion battery in this experimental example are as follows:

As shown in Figure 1, the preparation of the positive electrode sheet: using NMP as the solvent, add 95%wt% of the positive electrode active material lithium cobaltate, 2wt% of the binder PVDF, and 3%wt of the conductive agent graphite into the NMO in proportion and stirred to form a positive electrode active material with a viscosity in the range of 2500-8000 Pa·s. The positive electrode active material was coated on the positive electrode current collector aluminum foil to form a positive electrode active material layer, and uncoated regions were formed at both ends. After drying and cold pressing, the compacted density is 4.15g/cc. Die-cutting is used to die-cut the positive pole piece in the area corresponding to the positive tab on the first layer of the winding layer of the battery core to make the slot corresponding to the positive pole. The slot is in the active material layer on both sides at the same time, the size of the slot is 25 (long side size) * 11 (wide side size) mm, and green glue is pasted; then, the negative electrode is also die-cut The area corresponding to the ear is punched to make a slot corresponding to the negative electrode. The size of the negative electrode slot is 25*11 mm, and it is pasted with green glue. Weld the positive pole tab in the uncoated area, the width of the positive pole tab is 6.0 mm, the thickness is 0.06 mm, and the length is 40.0 mm.

Preparation of the negative electrode sheet: with deionized water as solvent, add 95wt% negative electrode active material graphite, 2wt% binder SBR, 2wt% conductive agent graphite and 1wt% thickener CMC to deionized water, stir A negative electrode active material with a viscosity ranging from 1000 to 3500 Pa·s. The negative electrode active material was coated on the negative electrode current collector copper foil, dried, and cold pressed to obtain a compacted density of 1.65 g/cc. The negative pole piece is not die-cut, and the negative tab is directly welded in the uncoated area 100. The width of the negative tab is 6.0 mm, the thickness is 0.06 mm, and the length is 40.0 mm.

The used separator is a PP/PE/PP three-layer composite porous separator with a thickness of 11 μm.

The electrolyte is a LiPF ₆ solution with a concentration of 1mol/L. The solvent is a mixed solvent of EC, PC and DEC, and the ratio of the three is 1:1:1.

Battery assembly: After winding the positive pole piece, separator and negative pole piece into the cell structure shown in Figure 2, a battery core with a model number of 354798 is formed, which is packaged, liquid injected, chemically formed, and pumped to form a high-efficiency battery. Energy density secondary battery.

Experimental example 2:

The difference from Experimental Example 1 is:

Both the positive electrode slot and the negative electrode slot are located on the 8th layer of the battery winding layer.

Experimental example 3:

The difference from Experimental Example 1 is:

Both the positive electrode slot and the negative electrode slot are located in the 10th layer (the outermost layer) of the winding layer of the battery core, and the coated area of the active material layer on the inner side of the positive electrode slot and the negative electrode slot overlaps with the uncoated area on the outer side. within the area.

Experimental example 4:

The difference from Experimental Example 1 is:

The long side dimension of the positive electrode slot and the negative electrode slot is 15 mm, the width of the positive electrode and the negative electrode lug is 6.0 mm, the thickness is 0.06 mm, and the length is 30 mm.

Experimental example 5:

The difference from Experimental Example 1 is:

The long side dimension of the positive electrode slot and the negative electrode slot is 10 mm, the width of the positive electrode and the negative electrode lug is 6.0 mm, the thickness is 0.06 mm, and the length is 25 mm.

Experimental example 6:

The difference from Experimental Example 1 is:

The wide side dimension of the positive electrode slot and the negative electrode slot is 9 mm.

Experimental example 7:

The difference from Experimental Example 1 is:

The wide side dimension of the positive electrode slot and the negative electrode slot is 7 mm.

Comparative example 1:

The difference from Experimental Example 1 is:

No die-cutting process was performed on the positive electrode sheet, that is, the slots 16 for the positive electrode and the negative electrode were not prepared, and the winding was completed according to FIG. 4 .

Comparative example 2:

The difference from Experimental Example 1 is:

The positive pole piece is not die-cut. According to the technical solution provided by the patent number 201420030319.4, the active material in a certain area on the positive pole piece and the negative pole piece is removed by laser or other mechanical cleaning methods, and the positive pole piece and the negative pole piece are cleaned. The ear 14 adopts laser welding in the area vacated after the active material is removed on each pole piece (refer to FIG. 5 ) and pastes insulating glue 18 on both sides of the welding place of the pole piece 14, and, when winding to form a battery core, no longer An uncoated area for connecting tabs 14 is reserved at the center of the cell, and the structure of the cell is shown in FIG. 6 .

Performance comparisons were made for Experimental Examples 1 to 7 and Comparative Examples 1 and 2. The results are shown in the table below:

Comparing Experimental Example 1 and Comparative Example 1, the cell structure corresponding to Experimental Example 1 improves the effective use of space for the battery, thereby improving the energy density of the battery.

Comparing Example 1 and Comparative Example 2, after 200 cls, the cell structure corresponding to Experimental Example 1 can improve the deformation problem during the battery cycle.

Comparing Experimental Example 1 and Experimental Example 3, the structure in which the groove position 16 is in the area where the uncoated region 100 overlaps with the active material layer 12 is compared with the structure in which the groove position 16 is in the area where the active material layers 12 on both sides overlap, the battery The energy density can be higher.

Comparing Experimental Examples 1, 4, 5, 6, and 7, the size of the slot 16 is optimized, the smaller the size of the slot 16, the higher the energy density of the battery.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, various modifications and changes may be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (10)

1. an electrode plates, comprise collector, active material layer and lug, described active material layer is coated on the surface of described collector, and all leave uncoated district at the two ends of the length direction of described collector, described lug is arranged in a described uncoated district, it is characterized in that, also comprise slot

Described slot is opened in described collector and is coated with in the region of described active material layer, and when described electrode plates winding forms battery core, the position one_to_one corresponding of the described lug of the position of described slot and positive pole and/or negative pole,

Described slot is the configuration that three bandings close openings at one side, comprises a broadside and two relative long limits, and the size on described long limit and the size of described broadside are all not less than the corresponding size of the join domain in described lug corresponding to it and described uncoated district.

2. electrode plates according to claim 1, is characterized in that, the two sides of described slot is provided with insulating cement, described insulating cement at least with the outer side bonds on two described long limits of described slot, and cross over described slot along the bearing of trend of described broadside.

3. electrode plates according to claim 1, is characterized in that, described insulating cement covers described slot completely, and with two described long limits of described slot and the outside of a described broadside all bonding.

4. electrode plates according to claim 1, it is characterized in that, the both side surface of described collector is coated with described active material layer, and the described active material layer being positioned at a side surface of described collector exists overlapping with the projection of described active material layer on described collector being positioned at described collector opposite side surface

Described slot is opened in this overlapping region, and described slot is in the region of the described active material layer of described collector both sides simultaneously.

5. electrode plates according to claim 1, it is characterized in that, the both side surface of described collector is coated with described active material layer, and the described uncoated district being positioned at a side surface of described collector exists overlapping with the projection of described active material layer on described collector being positioned at described collector opposite side surface

Described slot is opened in this overlapping region, and described slot is in the region of the described collector wherein described active material layer of side, and is in the described uncoated district of described collector opposite side.

6. a battery core, it is characterized in that, the anode pole piece comprising barrier film and be made up of the electrode plates described in any one of claim 1 to 5 and/or cathode pole piece, described anode pole piece, described cathode pole piece and described barrier film form winding battery core, described slot quantity summation on described anode pole piece and described cathode pole piece is two, and the position one_to_one corresponding of the described lug of the position of two described slots and positive pole and negative pole.

7. battery core according to claim 6, is characterized in that, two described slots are all arranged on described anode pole piece.

8. battery core according to claim 6, it is characterized in that, slot described at least one is arranged on described cathode pole piece, and described active material layer is not exposed across the region that barrier film described in one deck is relative in the described slot described anode pole piece is arranged on this on described cathode pole piece.

9. battery core according to claim 8, is characterized in that, the described slot described anode pole piece is arranged on this on described cathode pole piece does not apply described active material layer across the region that barrier film described in one deck is relative.

10. battery core according to claim 8, is characterized in that, described anode pole piece being arranged on described slot on described cathode pole piece across the outer side covers of the described active material layer in the relative region of barrier film described in one deck with this has shielding layer.