Composite current collector, pole piece, battery cell and lithium battery
By setting blind holes on the polymer matrix and filling conductive parts, the problem of insolid welding of composite fluid collector electrodes is solved, and a higher welding success rate and improved production efficiency of lithium-ion batteries are achieved.
Patent Information
- Application Number
- CN202421432908.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-20
- Publication Date
- 2025-08-19
- Estimated Expiration
- 2034-06-20
AI Technical Summary
The existing composite liquid collectors are prone to insolid welding during the electrode welding process, affecting the performance and production efficiency of lithium batteries.
Blind holes are provided on the polymer matrix and conductive parts are filled. When the welding part of the conductive layer melts or breaks, the conductive parts flow to the conductive layer for replenishment, preventing the phenomenon of dummy welding and improving welding quality.
It improves the success rate of the electrode welding and the production efficiency of lithium-ion batteries, enhances the stability of welding and the conductivity of the battery.
Smart Images
Figure CN223245634U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of lithium-ion batteries, and in particular to a composite current collector, a pole piece, a battery core and a lithium battery. Background Art
[0002] With the strategic measures to address climate change and promote green development, lithium batteries as an important energy storage device have been widely studied. Achieving high capacity and lightweight lithium batteries while ensuring their safety has always been the industry's goal.
[0003] Traditional current collectors use metal foil, which has good conductivity. To adapt to the development trend of lithium batteries, its thickness has been reduced. However, this is accompanied by a decline in mechanical properties. During the coating and roll-pressing process of the battery, it is prone to defects such as protrusions, holes, and even fractures. This not only affects the safety performance of the battery, but also increases the manufacturing cost. This has led to the development of composite current collectors, which are based on polymer materials with good insulation, low density, and low cost.
[0004] However, since the copper foil in the composite current collector is relatively thin, the heat generated during the welding process of the tabs can easily melt the copper foil and expand the polymer layer in the composite current collector, thereby causing the melted copper foil to flow and become disconnected and wrinkled, resulting in the tabs being connected to the polymer matrix. The bonding force between the tabs and the copper foil is poor, which ultimately has a negative impact on the performance of the composite current collector and the lithium-ion battery. Utility Model Content
[0005] The main purpose of the utility model is to provide a composite current collector, aiming to solve the problem that the welding of the existing composite current collector tabs easily leads to loose welding.
[0006] To achieve the above objectives, the present invention provides a composite current collector, which comprises:
[0007] A polymer matrix having a first surface and a second surface disposed opposite to each other, and further having a first blind hole extending from the first surface toward the second surface;
[0008] a first conductive member, wherein the first conductive member is filled in the first blind hole;
[0009] a first conductive layer, the first conductive layer being disposed on the first surface;
[0010] The first conductive layer includes a first welding portion for welding the tab, and the first welding portion at least covers the first blind hole and is connected to the first conductive member.
[0011] In some embodiments, the polymer matrix has a first region, a second region, and a third region, the first region or the third region is arranged corresponding to the first welding portion, and the second region is located between the first region and the third region;
[0012] There are a plurality of first blind holes, some of which extend from the first surface of the first region toward the second surface, and another portion of which extend from the first surface of the third region toward the second surface.
[0013] In some embodiments, the polymer matrix further has a second blind hole extending from the second surface toward the first surface, and a second conductive member is disposed in the second blind hole;
[0014] The composite current collector also includes a second conductive layer, which is arranged on the second surface; there are multiple second blind holes, some of which extend from the second surface toward the first surface of the first region, and another part of the second blind holes extend from the second surface toward the first surface of the third region.
[0015] In some embodiments, the first region includes a first edge and a second edge disposed opposite to each other, the third region includes a third edge and a fourth edge disposed opposite to each other, the second region is connected to the second edge and the third edge respectively, the distance between the first edge and the second edge is a, the distance between the third edge and the fourth edge is b, and the distance between the first edge and the fourth edge is c, where the range of (a+b) / c is 0.2 to 0.25.
[0016] In some embodiments, the polymer matrix further has a through hole extending from the first surface of the second region to the second surface, the composite current collector further includes a third conductive member, the third conductive member is filled in the through hole, and the two ends of the third conductive member are respectively connected to the first conductive layer and the second conductive layer; and / or,
[0017] The second conductive member is a copper column deposited and formed in the second blind hole or an aluminum column deposited and formed in the second blind hole.
[0018] In some embodiments, the porosity of the first region and the porosity of the third region are both greater than the porosity of the second region.
[0019] In some embodiments, the first conductive member is a copper column deposited and formed in the first blind hole, or an aluminum column deposited and formed in the first blind hole.
[0020] The utility model further discloses a pole piece, comprising an active material layer and the composite current collector described in the aforementioned embodiment, wherein the active material layer is arranged on the first conductive layer.
[0021] The present invention further discloses a battery cell, comprising a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet, and at least one of the positive electrode sheet and the negative electrode sheet is the electrode sheet described in the aforementioned embodiment.
[0022] The utility model further discloses a lithium battery, comprising a shell and the battery core described in the above embodiment, wherein the battery core is arranged in the shell.
[0023] The utility model provides a first blind hole on the polymer matrix and fills the first conductive member in the first blind hole, so that when welding the tab, if the welding area, that is, the first welding portion of the first conductive layer, melts, wrinkles, or breaks, the first conductive member will also melt and flow to the first conductive layer to replenish the first conductive layer, thereby better preventing the occurrence of cold welding between the tab and the first conductive layer, improving the welding quality, and further improving the success rate of the tab welding and the production efficiency of the lithium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a cross-sectional view of a polymer matrix in an embodiment of the composite current collector of the present invention;
[0025] Figure 2 This is a schematic structural diagram of the first conductive layer in an embodiment of the composite current collector of the present invention;
[0026] Figure 3 This is a top view of the polymer matrix in another embodiment of the composite current collector of the present invention;
[0027] Figure 4 This is a schematic structural diagram of an embodiment of the composite current collector of the present utility model;
[0028] Figure 5 This is a cross-sectional view of the polymer matrix in another embodiment of the composite current collector of the present invention. Description of the drawings:
[0030] 100, polymer matrix; 110, first surface; 120, second surface; 111, first region; 112, second region; 113, third region; 130, first blind hole; 140, second blind hole; 150, through hole; 200, first conductive layer; 210, first welding portion; 300, second conductive layer. DETAILED DESCRIPTION
[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the schemes in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts are within the scope of protection of the present invention.
[0032] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.
[0033] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element.
[0034] In addition, the descriptions of "first," "second," etc. in this utility model are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this utility model.
[0035] The utility model proposes a composite current collector, referring to Figure 1 and Figure 2 , the composite current collector comprises:
[0036] The polymer matrix 100 has a first surface 110 and a second surface 120 disposed opposite to each other, and the polymer matrix 100 further has a first blind hole 130 extending from the first surface 110 toward the second surface 120;
[0037] A first conductive member, the first conductive member is filled in the first blind hole 130;
[0038] A first conductive layer 200 , the first conductive layer 200 is disposed on the first surface 110 ;
[0039] The first conductive layer 200 includes a first welding portion 210 for welding the tab. The first welding portion 210 at least covers the first blind hole 130 and is connected to the first conductive member.
[0040] The composite current collector comprises a polymer matrix 100 and a first conductive layer 200 disposed thereon. The dimensions of the first conductive layer 200 can be selected as needed and are not limited in this embodiment. The first conductive layer 200 exhibits excellent electrical conductivity, ensuring efficient current transmission within the battery. For example, it can be made of a carbon-based conductive material or a metal conductive material. The metal conductive material can be at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, and aluminum-zirconium alloy. The carbon-based conductive material can be at least one of graphite, acetylene black, graphene, and carbon nanotubes. The first conductive layer 200 includes a first welding portion 210 for welding the tab. Since multiple tabs may need to be welded to the composite current collector, the first welding portions 210 can be a continuous, integral piece or dispersed. Their number, size, shape, and location can be selected as needed. It is understood that the area of the first welding portion 210 is controlled to be larger than the actual tab welding area to improve the tolerance for tab welding and prevent errors that could result in the tab being welded to other parts of the first conductive layer 200. Preferably, the thickness of the first welding portion 210 is greater than the thickness of other portions of the first conductive layer 200 , so that the tab is more firmly welded to the first welding portion 210 .
[0041] The polymer matrix 100 can be selected from polymer materials used in conventional composite current collectors, such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyetheretherketone, polyimide, polyamide, polyethylene glycol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, polyvinylidene fluoride-hexafluoropropylene, poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, polyethylene, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester and polysulfone and at least one of their derivatives.
[0042] First blind holes 130 are formed in the polymer matrix 100. These blind holes are pores that do not penetrate the entire thickness of the material. Various methods exist for creating the first blind holes 130, including laser drilling, mechanical drilling, chemical etching, and plasma etching. This embodiment typically utilizes laser drilling, which offers high precision and can produce first blind holes 130 with smaller diameters, allowing them to be more evenly distributed throughout the polymer matrix 100. The first conductive member can be connected to the first blind hole 130 by first processing it to a suitable size and then inserting it into the first blind hole 130. Alternatively, the conductive material (such as aluminum or copper) can be heated to an evaporation temperature in a high vacuum environment to release its atoms or molecules, and then deposited on the first surface 110 of the polymer matrix 100 and in the first blind hole 130. It should be noted that in this case, the material of the first conductive member and the first conductive layer 200 is the same. However, when other connection methods are used, the materials of the first conductive member and the first conductive layer 200 can be different. For example, the first conductive member can be a copper column and the first conductive layer 200 can be a nickel metal layer. This is not limited in the present invention.
[0043] The present invention provides a first blind hole 130 on the polymer matrix 100 and fills the first blind hole 130 with a first conductive member. When welding the tab, if the welding area, that is, the first welding portion 210 of the first conductive layer 200, melts, wrinkles, or breaks, the first conductive member will also melt and flow to the first conductive layer 200 to replenish the first conductive layer 200, thereby better preventing the occurrence of cold welding between the tab and the first conductive layer 200, improving the welding quality, and thereby improving the yield rate and production efficiency of the lithium-ion battery.
[0044] like Figure 3 As shown, in some embodiments, the polymer matrix 100 has a first region 111, a second region 112 and a third region 113, the first region 111 or the third region 113 is arranged corresponding to the first welding portion 210, and the second region 112 is located between the first region 111 and the third region 113;
[0045] There are multiple first blind holes 130 , some of which extend from the first surface 110 of the first region 111 toward the second surface 120 , and another portion of which extends from the first surface 110 of the third region 113 toward the second surface 120 .
[0046] The first region 111 and the third region 113 are usually arranged at the upper and lower ends of the composite current collector and correspond to the first welding portion 210, that is, the welding area of the tab, so that tabs can be welded on both sides of the composite current collector to increase the conductive path and improve the current carrying capacity.
[0047] The first blind holes 130 extend from the first region 111 toward the second surface 120. The extension direction can be perpendicular to the first surface 110 or at an angle to the first surface 110. It is sufficient that the openings of the first blind holes 130 are located in the first region 111. The presence of multiple first blind holes 130 allows the first conductive member within the first blind holes 130 to flow more evenly to the first conductive layer 200, thereby improving the welding strength of the tab.
[0048] like Figure 3-Figure 5 As shown, in some embodiments, the polymer matrix 100 further has a second blind hole 140 extending from the second surface 120 toward the first surface 110, and a second conductive member is disposed in the second blind hole 140;
[0049] The composite current collector also includes a second conductive layer 300, which is disposed on the second surface 120; there are multiple second blind holes 140, some of which extend from the second surface 120 toward the first surface 110 of the first region 111, and another portion of the second blind holes 140 extends from the second surface 120 toward the first surface 110 of the third region 113.
[0050] Conductive layers are provided on both the first surface 110 and the second surface 120 of the composite current collector to improve the conductivity of the composite current collector, reduce resistance, and reduce the heat that may be generated by the single-sided conductive layer due to current concentration. The double-sided conductive layer can also increase the overall strength and rigidity of the composite current collector, improve its mechanical properties, and reduce the risk of deformation during use. The second blind hole 140 is set in a similar manner to the first blind hole 130 and will not be repeated here. It should be noted that in order to prevent the second blind hole 140 from being connected to the first blind hole 130, the positions of the two can be set in a staggered manner, or the depths of the second blind hole 140 and the first blind hole 130 can be controlled to be less than half the thickness of the polymer matrix 100.
[0051] It is understandable that the second conductive layer 300 is provided on the composite current collector, and the second surface 120 of the polymer matrix 100 can also be divided into a fourth region, a fifth region and a sixth region with reference to the first surface 110 , which will not be repeated here.
[0052] like Figure 3 As shown, in some embodiments, the first region 111 includes a first edge and a second edge disposed opposite to each other, the third region 113 includes a third edge and a fourth edge disposed opposite to each other, the second region 112 is connected to the second edge and the third edge respectively, the distance between the first edge and the second edge is a, the distance between the third edge and the fourth edge is b, and the distance between the first edge and the fourth edge is c, where the range of (a+b) / c is 0.2 to 0.25.
[0053] That is, the first region 111, the second region 112 and the third region 113 are long strips, and the first region 111 and the second region 112 occupy 20% to 25% of the entire first surface 110, corresponding to the first welding portion 210 and other parts of the first conductive layer 200. This can not only firmly weld the tabs, but also avoid occupying too much space as much as possible, ensuring that a sufficiently large active material layer can be set on the first conductive layer 200.
[0054] Preferably, the first region 111 and the second region 112 are symmetrically arranged, which not only facilitates drilling but also increases the accuracy of tab welding, thereby evenly distributing current and heat on the current collector and reducing the risk of short circuit and thermal runaway.
[0055] like Figure 3 As shown, in some embodiments, the polymer matrix 100 further has a through hole 150 extending from the first surface 110 of the second region 112 to the second surface 120, and the composite current collector further includes a third conductive member, the third conductive member is filled in the through hole 150, and the two ends of the third conductive member are respectively connected to the first conductive layer 200 and the second conductive layer 300; and / or, the second conductive member is a copper column deposited and formed in the second blind hole 140 or an aluminum column deposited and formed in the second blind hole 140.
[0056] A through hole 150 is opened in the second region 112 , and the first conductive layer 200 and the second conductive layer 300 are connected via a third conductive member, thereby improving the conductivity of the composite current collector, reducing resistance, and thereby improving the charge and discharge performance of the lithium-ion battery.
[0057] Copper and aluminum have excellent electrical conductivity and are relatively low in cost, making them ideal raw materials for the second conductive element. Their regular columnar shape also makes them easier to process. Preferably, the second conductive element and the second conductive layer 300 can be made of the same material. For example, if the second conductive adhesive is a copper column, the second conductive layer 300 can also be made of a copper metal layer. This same material allows the second conductive element to be better integrated into the second conductive layer 300 and can significantly reduce the risk of excessively high resistance in certain areas of the second conductive layer 300, minimizing safety risks.
[0058] like Figure 3 As shown, in some embodiments, the porosity of the first region 111 and the porosity of the third region 113 are both greater than the porosity of the second region 112 .
[0059] By controlling the porosity of the first region 111 and the third region 113 to be larger, the first conductive member and the second conductive member are made relatively denser, which can greatly improve the strength of the tab welding area, thereby making the tab welding more stable and firm.
[0060] Preferably, the porosity of the first region 111 and the third region 113 is controlled to be 60%-65%, and the porosity of the second region 112 is controlled to be 40%-45%.
[0061] In some embodiments, the first conductive member is a copper column deposited and formed in the first blind hole 130 or an aluminum column deposited and formed in the first blind hole 130. The configuration of the first conductive member is similar to that of the second conductive member and will not be repeated here.
[0062] The present invention further proposes a pole piece, comprising an active material layer and a composite current collector. The specific structure of the composite current collector refers to the above-mentioned embodiment. Since this pole piece adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the technical effects brought about by the technical solutions of the above-mentioned embodiments, which will not be described in detail here. The active material layer is provided on the first conductive layer 200. It can be understood that when the composite current collector is provided with the first conductive layer 200 and the second conductive layer 300, the active material layer is provided on the first conductive layer 200 and the second conductive layer 300, respectively.
[0063] The present invention further proposes a battery cell comprising a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet, and at least one of the positive electrode sheet and the negative electrode sheet adopts the electrode sheet of the aforementioned embodiment.
[0064] Since this battery cell adopts all the technical solutions of all the above embodiments, it has at least all the technical effects brought by the technical solutions of the above embodiments, which will not be described in detail here. It is worth mentioning that the battery cell in this embodiment can be a wound core or a laminated cell.
[0065] The present invention further provides a lithium battery comprising a housing and the battery cell of the aforementioned embodiment, the battery cell being disposed within the housing. The specific structure of this lithium battery is similar to that of the aforementioned embodiment. Since all technical solutions of all of the aforementioned embodiments are employed, this battery exhibits at least all the technical effects of the aforementioned embodiments, and therefore will not be further detailed here.
[0066] The above description is only part or preferred embodiments of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural transformations made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.
Claims
1. A composite current collector, characterized in that: include: A polymer matrix having a first surface and a second surface disposed opposite to each other, and further having a first blind hole extending from the first surface toward the second surface; a first conductive member, wherein the first conductive member is filled in the first blind hole; a first conductive layer, the first conductive layer being disposed on the first surface; The first conductive layer includes a first welding portion for welding the tab, and the first welding portion at least covers the first blind hole and is connected to the first conductive member.
2. The composite current collector according to claim 1, characterized in that The polymer matrix has a first region, a second region and a third region, the first region or the third region is arranged corresponding to the first welding portion, and the second region is located between the first region and the third region; There are a plurality of first blind holes, some of which extend from the first surface of the first region toward the second surface, and another portion of which extend from the first surface of the third region toward the second surface.
3. The composite current collector according to claim 2, characterized in that: The polymer matrix further has a second blind hole extending from the second surface toward the first surface, and a second conductive member is disposed in the second blind hole; The composite current collector also includes a second conductive layer, which is arranged on the second surface; there are multiple second blind holes, some of which extend from the second surface toward the first surface of the first region, and another part of the second blind holes extend from the second surface toward the first surface of the third region.
4. The composite current collector according to claim 2 or 3, characterized in that: The first area includes a first edge and a second edge arranged opposite to each other, the third area includes a third edge and a fourth edge arranged opposite to each other, the second area is connected to the second edge and the third edge respectively, the distance between the first edge and the second edge is a, the distance between the third edge and the fourth edge is b, and the distance between the first edge and the fourth edge is c, where the range of (a+b) / c is 0.2 to 0.
25.
5. The composite current collector according to claim 3, characterized in that: The polymer matrix further has a through hole extending from the first surface of the second region to the second surface, the composite current collector further includes a third conductive member, the third conductive member is filled in the through hole, and two ends of the third conductive member are respectively connected to the first conductive layer and the second conductive layer; and / or, The second conductive member is a copper column deposited and formed in the second blind hole or an aluminum column deposited and formed in the second blind hole.
6. The composite current collector according to claim 2 or 3, characterized in that: The porosity of the first region and the porosity of the third region are both greater than the porosity of the second region.
7. The composite current collector according to any one of claims 1 to 3, characterized in that: The first conductive member is a copper column deposited and formed in the first blind hole or an aluminum column deposited and formed in the first blind hole.
8. A pole piece, characterized in that: The composite current collector comprises an active material layer and the composite current collector according to any one of claims 1 to 7, wherein the active material layer is provided on the first conductive layer.
9. A battery cell, characterized in that: The invention comprises a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet, and at least one of the positive electrode sheet and the negative electrode sheet is the electrode sheet described in claim 8.
10. A lithium battery, characterized in that: The invention comprises a shell and the battery core as claimed in claim 9, wherein the battery core is arranged in the shell.