Composite current collector and battery with same

Abstract

The utility model provides a composite current collector and a battery with the composite current collector, and the composite current collector comprises a polymer base material which is provided with two oppositely arranged bonding surfaces; the two confluence metal layers are respectively arranged on the two bonding surfaces; and the active metal layer is arranged on the outer surface of the confluence metal layer. Through the technical scheme provided by the invention, the problem that the improvement effect of the energy density of the battery cell is limited in the related technology can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a composite current collector and a battery having the same. Background Art

[0002] With the country's strong support for green energy and new energy vehicles, lithium-ion batteries have been widely used as a key link. At present, the two biggest considerations for new energy vehicles are the vehicle's mileage and the safety of new energy vehicles. Based on this, the design and manufacture of high-energy density and high-safety batteries have become the focus of attention.

[0003] In related technologies, in order to improve the energy density and safety of batteries, people pay more and more attention to the lightweight design and safety design of batteries. In addition to developing battery materials with high specific capacity, reducing the quality of various auxiliary materials inside the battery has also become one of the better strategies to improve the energy density of batteries. Among them, the use of current collectors is indispensable in commercial lithium batteries, and the current collectors account for a large proportion of the mass of the battery cell.

[0004] At present, the main idea of ​​improving the current collector technology is to reduce the quality of the current collector, and the main means include thinning the thickness of the current collector, perforated foil, etc. At present, these technologies have relatively simple ideas for improving the energy density of the battery cell, and the effect of improving the energy density of the battery cell is also limited. Utility Model Content

[0005] The utility model provides a composite current collector and a battery having the same, so as to solve the problem that the improvement effect of the energy density of the battery core in the related art is limited.

[0006] According to one aspect of the utility model, a composite current collector is provided, which includes: a polymer substrate having two oppositely arranged bonding surfaces; two bus metal layers, which are respectively arranged on the two bonding surfaces; and an active metal layer, which is arranged on the outer surface of the bus metal layer.

[0007] Furthermore, the bus metal layer includes a vacuum-plated layer and an electroplated layer, the vacuum-plated layer is arranged on the bonding surface, and the electroplated layer is arranged on the outer surface of the vacuum-plated layer.

[0008] Furthermore, the thickness of the vacuum coating is between 100 nm and 300 nm.

[0009] Furthermore, the thickness of the bus metal layer is between 900 nm and 2 μm.

[0010] Furthermore, the composite current collector includes two active metal layers, and the two active metal layers are respectively arranged on the outer surfaces of the two bus metal layers.

[0011] Furthermore, the active metal layer is an active coating layer arranged on the outer surface of the bus metal layer.

[0012] Furthermore, the material of the bus metal layer includes copper; and / or the material of the active metal layer includes lithium.

[0013] Furthermore, the material of the polymer substrate includes one or more of polyethylene, polypropylene, polyethylene terephthalate, and polyethylene terephthalate; and / or the thickness of the polymer substrate is between 2.5 μm and 12 μm.

[0014] Furthermore, the surface density of the composite current collector is 18 g / m 2 Up to 27g / m 2 between.

[0015] According to another aspect of the present invention, a battery is provided. The battery includes a positive electrode and a negative electrode. The negative electrode includes the composite current collector provided above.

[0016] The technical solution of the utility model is applied, and the composite current collector includes a polymer substrate, two bus metal layers and an active metal layer. The two bus metal layers are respectively arranged on two bonding surfaces of the polymer substrate, and the active metal layer is arranged on the outer surface of the bus metal layer. Among them, the composite current collector uses a polymer substrate as the substrate of the current collector, so that the mass of the battery cell is greatly reduced and the energy density is improved to a certain extent. Moreover, on this basis, the active metal layer on the outer surface of the bus metal layer can also be used to supplement the battery cell (for example, if the battery is a lithium battery, the active metal layer is lithium, and the active metal layer can supplement lithium to the battery cell), which can further improve the energy density of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0018] Figure 1 A schematic structural diagram of a composite current collector provided in an embodiment of the utility model is shown.

[0019] The above drawings include the following reference numerals:

[0020] 10. polymer substrate; 11. bonding surface;

[0021] 20. Bus metal layer;

[0022] 30. Active metal layer. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the utility model and its application or use. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0024] like Figure 1 As shown, the embodiment of the utility model provides a composite current collector, which includes a polymer substrate 10, two bus metal layers 20 and an active metal layer 30. The polymer substrate 10 has two oppositely arranged bonding surfaces 11, the two bus metal layers 20 are respectively arranged on the two bonding surfaces 11, and the active metal layer 30 is arranged on the outer surface of the bus metal layer 20.

[0025] By using the composite current collector provided in this embodiment, since the composite current collector uses the polymer substrate 10 as the substrate of the current collector, the mass of the battery cell is greatly reduced, and the energy density is improved to a certain extent. Moreover, on this basis, the active metal layer 30 on the outer surface of the bus metal layer 20 can also be used to supplement the battery cell (for example, if the battery is a lithium battery, the active metal layer 30 is lithium, and the active metal layer 30 can supplement lithium for the battery cell), which can further improve the energy density of the battery cell.

[0026] In addition, the efficient combination of current collector weight reduction technology and lithium replenishment technology can greatly improve the energy density of the battery cell, while greatly reducing the process cost and time cost of additional lithium replenishment of the battery cell.

[0027] In this embodiment, the bus metal layer 20 includes a vacuum-plated layer and an electroplated layer. The vacuum-plated layer is disposed on the bonding surface 11 , and the electroplated layer is disposed on the outer surface of the vacuum-plated layer.

[0028] Specifically, the bus metal layer 20 located on both sides of the polymer substrate 10 is vacuum plated at a temperature not higher than 10 - 4 The vacuum environment of Pa is plated on both sides of the polymer substrate 10 in a coating manner (vacuum coating process), so that the bus metal layer 20 is easily combined with the polymer substrate 10. The bus metal layer 20 is thickened by electroplating to have better conductivity and certain mechanical strength (electroplating process).

[0029] The thickness of the vacuum coating is between 100nm and 300nm, which is convenient for combining the bus metal layer 20 with the polymer substrate 10. The thickness of the bus metal layer 20 is between 900nm and 2μm, and the bus metal layer 20 has better conductivity and certain mechanical strength.

[0030] like Figure 1 As shown, the composite current collector includes two active metal layers 30 , and the two active metal layers 30 are respectively arranged on the outer surfaces of the two bus metal layers 20 , which is more convenient for reducing the weight of the composite current collector.

[0031] In this embodiment, the active metal layer 30 is an active coating layer disposed on the outer surface of the bus metal layer 20. -4 The active metal layer 30 is plated onto the outer surface of the bus metal layer 20 in a vacuum environment of Pa by means of film coating, so as to facilitate the combination of the active metal layer 30 and the bus metal layer 20 .

[0032] The material of the bus metal layer 20 includes copper, and the material of the active metal layer 30 includes lithium. Specifically, the purity of copper is ≥99.8%.

[0033] In this embodiment, the active metal lithium layer is evenly distributed on both sides of the bus metal layer 20 , and the thickness of the active metal layer 30 can be controlled according to different requirements.

[0034] The composite structure composed of the polymer substrate 10 and the bus metal layer 20 acts as the negative electrode current collector of the battery cell, which can reduce the weight of the current collector. The active metal lithium layer located outside the bus metal layer 20 can replenish lithium to the negative electrode of the battery cell later.

[0035] In other embodiments, the material of the active metal layer 30 can be selected according to the type of battery. For example, if the battery is a sodium ion battery, the material of the active metal layer 30 is sodium.

[0036] The material of the polymer substrate 10 includes one or more of polyethylene, polypropylene, polyethylene terephthalate, and polyethylene terephthalate. The thickness of the polymer substrate 10 is between 2.5 μm and 12 μm, which can reduce the weight of the composite current collector.

[0037] In this embodiment, the surface density of the composite current collector is 18 g / m 2 Up to 27g / m 2 It has the advantage of good lightweight effect, which is convenient for improving the energy density of the battery cell.

[0038] Another embodiment of the utility model provides a battery, the battery includes a positive electrode and a negative electrode, the negative electrode includes the composite current collector provided above. Therefore, the battery can also use the polymer substrate 10 to greatly reduce the mass of the battery core, improve the energy density to a certain extent, and use the active metal layer 30 on the outer surface of the bus metal layer 20 to supplement the battery core, further improving the energy density of the battery core.

[0039] In this embodiment, the battery is a lithium-ion battery, which includes a positive electrode, a negative electrode, a separator and an electrolyte, and the negative electrode includes the composite current collector provided above.

[0040] Among them, the mass percentage of negative electrode active material, conductive agent, binder and thickener is (92%~97%): (0.3%~0.6%): (1.8%~3.4%): (0.8%~1.7%); the mass ratio of positive electrode active material, conductive agent and binder is (92%~97%): (1.0%~3.2%): (1.5%~3.5%).

[0041] In other embodiments, the battery may also be other types of batteries, such as a sodium ion battery.

[0042] In order to facilitate understanding of the device provided in this embodiment, the following is an explanation in combination with a composite current collector and a method for manufacturing a battery having the same:

[0043] Embodiment 1:

[0044] A method for manufacturing a composite current collector and a battery having the same (polymer substrate + metal copper layer + metal lithium layer 50nm), comprising the following steps:

[0045] (1) Preparation of polymer substrate 10: Polypropylene is used as raw material to make polymer and materials with a thickness of 4um; (2) Vacuum plating + electroplating: -4 Pa vacuum environment, copper is plated onto the polymer substrate 10 to form a metal coating of about 200 nm, and then electroplating is used to thicken the metal layer, and finally a bus metal layer 20 with a total thickness of 1.0 μm on one side is obtained; (3) vacuum coating is used in a vacuum environment of not more than 10 -4 Pa vacuum environment, the active metal lithium layer is plated on both sides of the above-mentioned metal copper layer by coating, so that the thickness of the metal lithium layer on one side is 50nm; (4) Cell production: the positive electrode current collector is a commercial 12μm aluminum foil, the positive electrode uses lithium iron phosphate as the active material, and the slurry is prepared by oil-based wet mixing. The designed surface density of the positive electrode sheet is 424g / m 2The negative electrode uses graphite as the active material of the electrode, and the foil uses the composite current collector prepared by the above method. The mixed powder containing graphite, adhesive and conductive agent is directly rolled and bonded to the composite current collector prepared by the above method by a dry process. The pole piece design surface density is 194g / m 2 Finally, the finished battery cell is made through processes such as rolling, electrode slitting, cutting, lamination, welding and packaging, liquid injection, and chemical composition and capacity.

[0046] Embodiment 2:

[0047] A method for manufacturing a composite current collector and a battery having the same (polymer substrate + metal copper layer + metal lithium layer 100nm), comprising the following steps:

[0048] (1) Preparation of polymer substrate 10: Polypropylene is used as raw material to make polymer and materials with a thickness of 4um; (2) Vacuum plating + electroplating: -4 Pa vacuum environment, copper is plated onto the polymer substrate 10 to form a metal coating of about 200 nm, and then electroplating is used to thicken the metal layer, and finally a bus metal layer 20 with a total thickness of 1.0 μm on one side is obtained; (3) vacuum coating is used in a vacuum environment of not more than 10 -4 Pa vacuum environment, the active metal lithium layer is plated on both sides of the above-mentioned metal copper layer by coating, so that the thickness of the metal lithium layer on one side is 100nm; (4) Cell production: the positive electrode current collector is a commercial 12μm aluminum foil, the positive electrode uses lithium iron phosphate as the active material, and the slurry is prepared by oil-based wet mixing. The designed surface density of the positive electrode sheet is 424g / m 2 , compaction density 2.35g / cc; the negative electrode uses graphite as the active material of the electrode, and the foil uses the composite current collector prepared by the above method. A dry process is adopted to directly roll and bond the mixed powder containing graphite, adhesive and conductive agent through the equipment on the composite current collector prepared above. The designed surface density of the pole piece is 194g / m2. Finally, the finished battery cell is made through the processes of rolling, pole piece slitting, cutting, lamination, welding packaging, liquid injection, chemical composition and capacity.

[0049] Comparative Example 1:

[0050] A method for manufacturing a current collector and a battery having the same (polymer substrate + metal copper layer + inactive metal layer), comprising the following steps:

[0051] (1) Preparation of polymer substrate 10: Polypropylene is used as raw material to make polymer and materials with a thickness of 4um; (2) Vacuum plating + electroplating: -4Pa vacuum environment, copper is plated onto the polymer substrate 10 by coating to form a metal coating of about 200 nm, and then thickened by electroplating to finally obtain a bus metal layer 20 with a total thickness of 1.0 μm on one side; (3) Cell production: The positive electrode current collector is a commercial 12 μm aluminum foil, the positive electrode uses lithium iron phosphate as the active material, and the slurry is prepared by oil-based wet mixing. The designed surface density of the positive electrode sheet is 424 g / m 2 The negative electrode uses graphite as the active material of the electrode, and the foil uses the current collector prepared by the above method. The mixed powder containing graphite, adhesive and conductive agent is directly rolled and bonded to the composite current collector prepared by the above method through the equipment by dry process. The pole piece design surface density is 194g / m 2 Finally, the finished battery cell is made through processes such as rolling, electrode slitting, cutting, lamination, welding and packaging, liquid injection, and chemical composition and capacity.

[0052] Comparative Example 2:

[0053] A method for manufacturing a conventional current collector and a battery using the same (conventional current collector) comprises the following steps:

[0054] (1) The positive electrode current collector uses 12μm commercial aluminum foil, and the negative electrode uses 4.5μm commercial copper foil; (2) The positive electrode uses lithium iron phosphate as the active material, and the slurry is made by oil-based wet mixing. The designed surface density of the positive electrode sheet is 424g / m 2 The negative electrode uses graphite as the active material of the electrode, and the foil uses the above-mentioned 4.5um copper foil. The mixed powder containing graphite, adhesive and conductive agent is directly rolled and bonded to the composite current collector prepared above by a dry process. The pole piece design surface density is 194g / m 2 Finally, the finished battery cell is made through processes such as rolling, electrode slitting, cutting, lamination, welding and packaging, liquid injection, and chemical composition and capacity.

[0055] In particular, the battery cells of the above two groups of embodiments and two groups of comparative examples are exactly the same in design except that the current collectors used in the negative electrodes are different, including the positive and negative electrode formulations, surface density, compaction density, number of stacking layers, chemical composition and capacity processing, etc.

[0056] The performance of the current collectors prepared in Examples 1 and 2 and Comparative Examples 1 and 2 and the batteries using the current collectors were tested respectively, and the test data are shown in Table 1:

[0057]

[0058] As can be seen from Table 1, Comparative Example 1 uses a polymer as the base material of the current collector relative to the current collector in Comparative Example 2, which greatly reduces the weight of the battery cell and improves the energy density to a certain extent. Further, Example 1 uses a composite current collector on the basis of Comparative Example 2, which not only reduces the weight of the battery cell, but also replenishes the lithium of the graphite negative electrode, thereby significantly improving the capacity and energy density of the battery cell. Further, Example 2 further improves the capacity and energy density of the battery cell by adjusting the thickness of the active metal lithium layer on the composite current collector on the basis of Example 1.

[0059] The device provided by the embodiment has the following beneficial effects:

[0060] (1) The composite current collector has a unique structure, which efficiently combines the current collector weight reduction technology with the lithium replenishment technology, which can greatly increase the energy density of the battery cell and greatly reduce the process cost and time cost of additional lithium replenishment of the battery cell;

[0061] (2) The deposition of metallic lithium is directly achieved on the surface of the composite current collector by vacuum plating, which is easy to form an industrial scale;

[0062] (3) The thickness of the active metal lithium plating layer in the composite current collector can be controlled according to the requirements of different battery cells to achieve the desired lithium replenishment effect;

[0063] (4) This functional current collector can be used in batches in the electrode sheets of dry-process negative electrodes.

[0064] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0065] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the utility model. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0066] In the description of the present utility model, it needs to be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present utility model; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0067] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0068] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the utility model.

[0069] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A composite current collector, characterized in that: The composite current collector comprises: A polymer substrate (10) having two bonding surfaces (11) disposed opposite to each other; Two bus metal layers (20), the two bus metal layers (20) being respectively arranged on the two bonding surfaces (11); An active metal layer (30) is arranged on the outer surface of the bus metal layer (20).

2. The composite current collector according to claim 1, characterized in that: The bus metal layer (20) comprises a vacuum-plated layer and an electroplated layer, the vacuum-plated layer being arranged on the bonding surface (11), and the electroplated layer being arranged on the outer surface of the vacuum-plated layer.

3. The composite current collector according to claim 2, characterized in that: The thickness of the vacuum coating is between 100nm and 300nm.

4. The composite current collector according to any one of claims 1 to 3, characterized in that: The thickness of the bus metal layer (20) is between 900 nm and 2 μm.

5. The composite current collector according to any one of claims 1 to 3, characterized in that: The composite current collector comprises two active metal layers (30), and the two active metal layers (30) are respectively arranged on the outer surfaces of the two bus metal layers (20).

6. The composite current collector according to any one of claims 1 to 3, characterized in that: The active metal layer (30) is an active coating layer arranged on the outer surface of the bus metal layer (20).

7. The composite current collector according to any one of claims 1 to 3, characterized in that: The material of the bus metal layer (20) includes copper; and / or, The material of the active metal layer (30) includes lithium.

8. The composite current collector according to any one of claims 1 to 3, characterized in that: The material of the polymer substrate (10) includes one or more of polyethylene, polypropylene, polyethylene terephthalate, and polyethylene terephthalate; and / or, The thickness of the polymer substrate (10) is between 2.5 μm and 12 μm.

9. The composite current collector according to any one of claims 1 to 3, characterized in that: The surface density of the composite current collector is 18 g / m 2 Up to 27g / m 2 between.

10. A battery, characterized in that: The battery comprises a positive electrode and a negative electrode, and the negative electrode comprises the composite current collector according to any one of claims 1 to 9.

Images