Composite current collector, secondary battery and electronic equipment

Abstract

The utility model provides a composite current collector, a secondary battery and electronic equipment, at least comprising: a base material having a porous structure; the conductive polymer penetrates through the porous structure and is arranged on the two sides of the base material; and the metal layer is arranged on the other side of the composite side of the conductive polymer and the base material. According to the composite current collector, the secondary battery and the electronic equipment provided by the utility model, the two surfaces of the composite current collector can be conducted, and the composite current collector has good metal layer stripping force, conductivity and mechanical strength.

Description

TECHNICAL FIELD

[0001] The utility model relates to power battery technical field, concretely relates to a kind of composite current collector, secondary battery and electronic equipment. BACKGROUND

[0002] Under low-carbon economy, the competitiveness of new energy electric car gradually strengthens, but safety and "mileage anxiety" are the biggest resistance limiting its development. Among them, by introducing composite current collector, the energy density and safety of battery can be effectively improved, but composite current collector is mostly two-sided metalized non-polar polymer film, needs additional welding process to make its two sides conductive, so as to lead to complicated manufacturing process and increased manufacturing cost. At the same time, since non-polar polymer does not contain polar group, the adhesion of metal on non-polar polymer film is often low, and is easy to fall off. Moreover, the ductility of non-polar polymer is poor, and it is difficult to prepare composite current collector alone. SUMMARY

[0003] The utility model provides a kind of composite current collector, secondary battery and electronic equipment, can make the two sides of composite current collector conductive, and have good metal layer peel strength, conductivity and mechanical strength.

[0004] To solve the above technical problems, the utility model provides a kind of composite current collector, at least includes:

[0005] Base material, the base material has porous structure;

[0006] Conductive polymer, is arranged on the two sides of the base material through the porous structure;And

[0007] Metal layer, is arranged on the other side of the conductive polymer and the base material composite side.

[0008] In an embodiment of the utility model, the porosity of the base material is 30%-50%, and the tensile strength of the base material is >50MPa.

[0009] In an embodiment of the utility model, in the base material, the pore size of the porous structure is 3 μm-100 μm.

[0010] In an embodiment of the utility model, the total area of the porous structure is 100%, and the sum of the area of the pore with pore size >5 μm is accounted for >50%.

[0011] In an embodiment of the utility model, the thickness of the base material is <10 μm.

[0012] In an embodiment of the utility model, the thickness of the conductive polymer is 2 μm-5 μm.

[0013] In an embodiment of the present application, the thickness of the metal layer is 0.5-3 microns.

[0014] In an embodiment of the present application, the material of the conductive polymer includes at least one of poly 3,4-ethylenedioxythiophene and polystyrene sulfonic acid.

[0015] The present application also provides a secondary battery including the composite current collector.

[0016] The present application also provides an electronic device including the secondary battery.

[0017] In summary, the present application provides a composite current collector, a secondary battery and an electronic device, which can realize the two-side conduction of the composite current collector, thereby omitting the subsequent welding process and reducing the preparation process and cost of the composite current collector. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description.

[0019] Figure 1 Figure 1 is a structural diagram of the composite current collector in an embodiment of the present application.

[0020] Figure 2 Figure 2 is a sectional view of the conductive polymer and the substrate in an embodiment of the present application. Figure 1 Figure 3 is an enlarged view of the conductive polymer and the substrate in an embodiment of the present application.

[0021] Label Description:

[0022] 11, substrate; 12, conductive polymer; 13, metal layer. DETAILED DESCRIPTION

[0023] The embodiments of the present application will be described below through specific concrete examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the present specification.

[0024] It is to be understood that the present application can be carried out in various forms and should not be construed to be limited to the examples set forth herein. Rather, these examples are provided so that this disclosure will be complete and fully convey the scope of the application to those skilled in the art.

[0025] The technical solutions of the present application will be further described in detail below in conjunction with the examples. Obviously, the described examples are only a part of the examples of the present application, rather than all the examples. Based on the examples in the present application, all the other examples obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0026] Please refer to Figures 1 to 2 As shown in the drawings, the present application provides a composite current collector, at least comprising a base material 11, a conductive polymer 12 and a metal layer 13, wherein the base material 11 has a porous structure, the conductive polymer 12 is arranged on both sides of the base material 11 through the porous structure, and the metal layer 13 is arranged on the other side of the conductive polymer 12 combined with the base material 11. In the composite current collector provided by the present application, by arranging the conductive polymer 12 through the porous structure in the base material 11, the two surfaces of the composite current collector can be realized to be conductive, so that the subsequent welding process can be omitted, and the preparation process and preparation cost of the composite current collector can be reduced. Moreover, the conductive polymer 12 can make up for the reduction of the mechanical strength of the base material 11 due to the porous structure, and can also neutralize the huge surface energy difference between the metal layer 13 and the base material 11, improve the adhesion of the metal layer 13 on the surface of the composite current collector, so that the composite current collector has good metal layer peeling force, conductive performance and mechanical strength.

[0027] Please refer to Figures 1 to 2As shown in the utility model one embodiment, the thickness of the substrate 11 is for example less than 10 microns, and the material includes for example at least one of non-polar polymers such as polypropylene (PP), polyethylene terephthalate (PET) and polyethylene (PE), so that the substrate 11 has insulation properties and can generate an open circuit effect, thereby preventing the puncture of the diaphragm, reducing thermal runaway and improving safety. The substrate 11 has a porous structure, and each porous structure penetrates the substrate 11 to serve as a channel for the subsequent conductive polymer 12 to communicate between the two sides of the substrate 11. Specifically, the porosity of the substrate 11 is for example 30%-50%, and the tensile strength is for example > 50 MPa, so as to improve the forming ability, bending resistance and flexibility of the substrate 11 and avoid excessive deformation of the substrate 11. The ratio of the volume of the porous structure in the substrate 11 to the total volume of the substrate 11 is defined as the porosity, and the maximum stress per unit area of the substrate 11 can withstand during stretching is defined as the tensile strength. In the porous structure of the substrate 11, the pore size is for example 3 microns to 100 microns, so that when the conductive polymer 12 is subsequently formed, the polymer solution can be infiltrated onto the surface of the substrate 11 through the porous structure. Furthermore, the total area of the porous structure is 100%, and the sum of the areas of the pores with a pore size > 5 microns accounts for > 50%. If the proportion is ≤ 50%, the polymer solution is not easy to infiltrate into the porous structure of the substrate 11 when the conductive polymer 12 is subsequently formed, thereby affecting the formation of the conductive polymer 12 and the processing rate of the composite current collector.

[0028] Please refer to Figures 1 to 2 As shown in the utility model one embodiment, when the substrate 11 is obtained, a non-polar polymer film is first formed for example by melt extrusion, and then the non-polar polymer film is stretched to form a porous structure in the non-polar polymer film. Next, the non-polar polymer film is subjected to corona treatment to form the substrate 11. In the process of melt extrusion, the linear speed affects the tensile strength of the non-polar polymer film, and the linear speed is for example 5 m / min to 30 m / min, so as to control the tensile strength of the non-polar polymer film to be > 50 MPa, thereby facilitating the subsequent stretching of the non-polar polymer film without breaking, and the porous structure can be formed. In the process of stretching the non-polar polymer film, the temperature of the non-polar polymer film is for example 100°C to 150°C, and the linear speed during stretching is for example 10 m / min to 50 m / min, so as to control the porosity and pore size distribution of the porous structure in the non-polar polymer film. In the corona process, the gradient of the electric field strength is for example 5000 V / m² to 20000 V / m².

[0029] Please refer to Figures 1 to 2As shown in the embodiment of the present application, the conductive polymer 12 is arranged through the porous structure on both sides of the substrate 11. The material of the conductive polymer 12 includes at least one of poly 3,4-ethylenedioxythiophene and polystyrene sulfonic acid (PSS), and the thickness is, for example, 2-5 μm. By arranging the conductive polymer 12 to connect both sides of the substrate 11, the two sides of the composite current collector can be made conductive, thereby omitting the welding process and reducing the preparation process and cost of the composite current collector. Moreover, the conductive polymer 12 can compensate for the reduction of the mechanical strength of the substrate 11 caused by the porous structure, thereby improving the overall mechanical strength of the composite current collector.

[0030] Referring to Figures 1 to 2 As shown in the embodiment of the present application, when the conductive polymer 12 is obtained, first, the polymer material and the solvent are mixed to obtain a polymer solution, and then the polymer solution is sprayed on both sides of the substrate 11 to fill the porous structure in the substrate 11 and infiltrate onto the surfaces of both sides of the substrate 11, and then the substrate 11 coated with the polymer solution is dried to form the conductive polymer 12 on both sides of the substrate 11. The solvent can be any component that does not corrode or dissolve the substrate 11, for example, at least one of water or acetone, and the polymer material includes at least one of poly 3,4-ethylenedioxythiophene and PSS, and the drying temperature is, for example, 50-100 °C. Specifically, in the embodiment, the polymer material includes, for example, poly 3,4-ethylenedioxythiophene and PSS, and the mass ratio of poly 3,4-ethylenedioxythiophene to PSS is, for example, (2-5):1.

[0031] Referring to Figures 1 to 2 As shown in the embodiment of the present application, the metal layer 13 is arranged on the other side of the composite side of the conductive polymer 12 and the substrate 11. The thickness of the metal layer 13 is, for example, 0.5-3 μm, and the material includes at least one of conductive metals such as copper and aluminum, and the metal layer 13 is obtained by, for example, evaporation or magnetron sputtering. Since the material of the substrate 11 is a non-polar polymer without polar groups, the adhesion of the metal layer 13 to the substrate 11 is low and easy to separate. Therefore, in the embodiment, the conductive polymer 12 is arranged between the metal layer 13 and the substrate 11, and the material of the conductive polymer 12 contains polar groups, which can neutralize the large difference in surface energy between the metal layer 13 and the substrate 11, so that the metal layer 13 is not easy to separate from the substrate 11 and the conductive polymer 12, and the adhesion of the metal layer 13 to the substrate 11 and the conductive polymer 12 is improved, thereby making the composite current collector have good metal layer peeling force and conductivity.

[0032] Referring to Figures 1 to 2As shown, the utility model also provides a kind of secondary battery, at least including the composite current collector of above-mentioned. Among them, secondary battery is for example lithium ion battery, sodium ion battery, magnesium ion battery, calcium ion battery or potassium ion battery etc., secondary battery is also for example soft package battery, hard-shell battery or cylindrical battery etc., the kind of secondary battery is not specifically limited in the utility model. In the embodiment, lithium ion soft package battery is taken as an example, and secondary battery is described. Specifically, secondary battery is for example including positive pole sheet, negative pole sheet, diaphragm and electrolyte etc., diaphragm is arranged between positive pole sheet and negative pole sheet, and electrolyte is filled between positive pole sheet, negative pole sheet and diaphragm.

[0033] As shown in the drawings, Figures 1 to 2 As shown, in the utility model an embodiment, positive pole sheet includes positive pole current collector and at least the positive pole active layer coated on the one side surface of positive pole current collector, and negative pole sheet includes negative pole current collector and at least the negative pole active layer coated on the one side surface of negative pole current collector. Among them, positive pole current collector and / or negative pole current collector are the composite current collector described above.

[0034] As shown in the drawings, Figures 1 to 2 As shown, the utility model also provides a kind of electronic equipment, and electronic equipment includes at least one above-mentioned secondary battery, and secondary battery is used to provide electric energy. Among them, electronic equipment can be vehicle, mobile phone, portable device, notebook computer, ship, spacecraft, electric toy and electric tool etc. In the utility model an embodiment, vehicle is for example new energy vehicle, and new energy vehicle can be pure electric vehicle, hybrid electric vehicle or range extended vehicle etc. Spacecraft includes aircraft, rocket, space shuttle and spacecraft etc., and electric toy includes fixed or mobile electric toy, for example including game machine, electric car toy, electric ship toy and electric aircraft toy etc. Electric tool includes metal cutting electric tool, grinding electric tool, assembly electric tool and railway electric tool, for example including electric drill, electric grinder, electric wrench, electric screwdriver, electric hammer, impact drill, concrete vibrator and electric planer etc. Electronic equipment includes above-mentioned secondary battery, so it includes the advantages of above-mentioned secondary battery, and here is not more elaborated.

[0035] The utility model will be explained more specifically below by referring to the embodiments, which should not be understood as limiting. In the range consistent with the main idea of the utility model, appropriate modifications can be made, which all fall within the technical scope of the utility model.

[0036] Embodiment 1

[0037] The PP is melt-extruded at a line speed of 10 m / min to obtain a PP film, and then the PP film is stretched at a stretching zone at 140°C at a line speed of 30 m / min, and a porous structure is generated in the PP film, and then the PP film is subjected to corona treatment under the condition of 10,000 V / m2 to obtain a substrate. The porosity of the substrate is 30%, the thickness is 5 μm, the tensile strength is 60 MPa, the pore size of the porous structure is 3 μm-100 μm, and the proportion of the sum of the areas of the pores with a pore size >5 μm in the total area of the porous structure is 55%.

[0038] An aqueous solution of poly 3,4-ethylenedioxythiophene and PSS with a mass ratio of 2.5:1 is sprayed on the substrate, and then dried in a drying zone at 70°C to form a conductive polymer on both sides of the substrate. The thickness of the conductive polymer is 3 μm.

[0039] An aluminum layer with a thickness of 1 μm is evaporated on the conductive polymer to obtain a composite current collector.

[0040] Example 2

[0041] The line speed of melt extrusion is adjusted so that the tensile strength of the substrate is 70 MPa, and the other steps are the same as in Example 1.

[0042] Example 3

[0043] The line speed of melt extrusion is adjusted so that the tensile strength of the substrate is 80 MPa, and the other steps are the same as in Example 1.

[0044] Example 4

[0045] The line speed and the temperature of the PP film during stretching are adjusted so that the porosity of the substrate is 40%, and the other steps are the same as in Example 1.

[0046] Example 5

[0047] The line speed and the temperature of the PP film during stretching are adjusted so that the porosity of the substrate is 50%, and the other steps are the same as in Example 1.

[0048] Example 6

[0049] The line speed and the temperature of the PP film during stretching are adjusted so that the proportion of the sum of the areas of the pores with a pore size >5 μm in the total area of the porous structure of the substrate is 60%, and the other steps are the same as in Example 1.

[0050] Example 7

[0051] The line speed and the temperature of the PP film during stretching are adjusted so that the proportion of the sum of the areas of the pores with a pore size >5 μm in the total area of the porous structure of the substrate is 70%, and the other steps are the same as in Example 1.

[0052] Example 8

[0053] The line speed of melt extrusion was adjusted so that the tensile strength of the substrate was 40 MPa, and the other steps were the same as in Example 1.

[0054] Example 9

[0055] The line speed during stretching and the temperature of the PP film were adjusted so that the porosity of the substrate was 20%, and the other steps were the same as in Example 1.

[0056] Example 10

[0057] The line speed during stretching and the temperature of the PP film were adjusted so that the porosity of the substrate was 60%, and the other steps were the same as in Example 1.

[0058] Example 11

[0059] The line speed during stretching and the temperature of the PP film were adjusted so that the ratio of the sum of the areas of the pores with a diameter > 5 μιη to the total area of the porous structure of the substrate was 40%, and the other steps were the same as in Example 1.

[0060] Comparative Example 1

[0061] There was no conductive polymer in the composite current collector, and the other steps were the same as in Example 1.

[0062] Comparative Example 2

[0063] There was no conductive polymer in the composite current collector, and there was no porous structure in the substrate, and the other steps were the same as in Example 1.

[0064] Comparative Example 3

[0065] There was no porous structure in the substrate, and the other steps were the same as in Example 1.

[0066] The parameters of the composite current collector in each example and comparative example are shown in Table 1.

[0067] Table 1, Parameters of the Composite Current Collector in Examples 1-11 and Comparative Examples 1-3

[0068]

[0069] As shown in Table 1, when testing the tensile strength of the substrate, the substrate was stretched using a tensile machine until the substrate broke, and the tensile strength at which the substrate broke was recorded.

[0070] As shown in Table 1, the porosity of the substrate was tested, for example, by the density method. Specifically, the substrate was immersed in a liquid with a known density, and the true density of the substrate was calculated by the liquid displacement method. Next, the mass and volume of the substrate were measured, and the apparent density of the substrate was calculated. Finally, the porosity was calculated according to the formula: porosity = (1 - apparent density / true density) x 100.

[0071] As shown in Table 1, the pore size and pore size distribution of the porous structure in the substrate are measured by a scanning electron microscope (SEM), for example. Specifically, the SEM is used to observe and take images of the surface of the substrate, and then an image analysis software is used to analyze the pore size and pore size distribution in the images, and the area ratio of the pores with a specific pore size in the total area of the porous structure is obtained by using the pore size distribution. The image analysis software is ImageJ, Fiji or Gwyddion, for example.

[0072] As shown in Table 1, the thickness of the conductive polymer is measured by a micrometer, for example, and the thickness of the metal layer is measured by scanning the cross section of the substrate by the SEM, for example.

[0073] In the utility model, the composite current collector prepared in examples 1-11 and comparative examples 1-3 is subjected to performance testing, and the test results are shown in Table 2.

[0074] In an embodiment of the utility model, the metal layer on the surface of the composite current collector is subjected to peel strength testing, for example. Specifically, an adhesive tape is pasted on the metal layer, and the adhesive tape is stretched at a speed of 300 mm / min until the adhesive tape is separated from the metal layer, and the peel strength when the adhesive tape is separated is recorded. The peel strength between the adhesive tape and the metal layer is greater than the peel strength between the metal layer and the conductive polymer, so as to ensure that the adhesive tape will not be torn from the surface of the metal layer. Specifically, the peel strength between the adhesive tape and the metal layer is greater than 5 N / cm.

[0075] In an embodiment of the utility model, the composite current collector is subjected to tensile strength testing, for example. Specifically, a tensile machine is used to stretch the composite current collector at a speed of 30 mm / min until the composite current collector is broken, and the tensile strength when the composite current collector is broken is recorded.

[0076] In an embodiment of the utility model, the composite current collector is subjected to resistance testing, for example. Specifically, a voltage is applied to both sides of the composite current collector, and the resistance of the composite current collector is tested.

[0077] Table 2, performance test results of the composite current collector in examples 1-11 and comparative examples 1-3

[0078]

[0079] As shown in Table 1 and Table 2, it can be seen from Comparative Example 2-3 that when the substrate has no porous structure, the peeling strength and tensile strength of the composite current collector are higher after the conductive polymer is arranged between the substrate and the metal layer, but the resistance is too large, which indicates that the conductive polymer can neutralize the large difference in surface energy between the metal layer and the substrate, so that the metal layer is not easy to separate from the substrate and the conductive polymer, and the adhesion of the metal layer on the substrate and the conductive polymer is improved, so that the composite current collector has good metal layer peeling force and mechanical strength, but the conductive performance of the composite current collector is not improved. However, it can be seen from Comparative Example 1 and Comparative Example 3 that when the substrate has a porous structure, after the conductive polymer is arranged between the substrate and the metal layer, although the tensile strength of the composite current collector is reduced, the resistance is small, which indicates that the conductive polymer can improve the conductive performance of the composite current collector by infiltrating into both sides of the substrate through the porous structure.

[0080] As shown in Table 1 and Table 2, it can be seen from Comparative Example 1 and Comparative Example 1-2 that when the substrate has a porous structure, the tensile strength of the composite current collector is reduced, but after the conductive polymer is arranged on both sides of the substrate with a porous structure, the tensile strength of the composite current collector is improved, which indicates that although the porous structure in the substrate will affect the mechanical strength of the composite current collector, the presence of the conductive polymer can make up for the loss of the mechanical strength of the composite current collector, so that the composite current collector still has good mechanical strength.

[0081] As shown in Table 1 and Table 2, it can be seen from Comparative Example 1-3 and Example 8 that as the tensile strength of the substrate increases from 40 MPa to 80 MPa, the tensile strength of the composite current collector gradually increases, which indicates that by controlling the tensile strength of the substrate, the mechanical strength of the composite current collector can be improved.

[0082] As shown in Table 1 and Table 2, it can be seen from Comparative Example 1, Example 4-5 and Example 9-10 that as the porosity of the porous structure in the substrate increases from 20% to 60%, the tensile strength and resistance of the composite current collector gradually decrease, which indicates that the increase of the porosity can improve the conductive performance of the composite current collector, but affect the mechanical strength of the composite current collector. Therefore, by controlling the porosity of the porous structure in the substrate, the conductive performance and mechanical strength of the composite current collector can be considered.

[0083] As shown in Table 1 and Table 2, it can be seen from Comparative Example 1, Example 6-7 and Example 11 that when the proportion of the sum of the pore area with a pore diameter > 5 μm in the total area of the porous structure of the substrate increases from 40% to 70%, the tensile strength and the resistance of the composite current collector gradually decrease, thereby indicating that increasing the proportion of the sum of the pore area with a pore diameter > 5 μm can improve the conductivity of the composite current collector, but affects the mechanical strength of the composite current collector. Therefore, by controlling the proportion of the sum of the pore area with a pore diameter > 5 μm in the total area of the porous structure of the substrate, the conductivity and the mechanical strength of the composite current collector can be considered.

[0084] In summary, the utility model provides a kind of composite current collector, secondary battery and electronic equipment, by being provided with conductive polymer in the both sides of substrate, through the porous structure in substrate, the both sides of composite current collector can be realized to be conducted, to be able to omit subsequent welding process, reduce the preparation process and preparation cost of composite current collector.And, conductive polymer is located between substrate and metal layer, can neutralize the huge surface energy difference between metal layer and substrate, improve the adhesion of metal layer on the surface of composite current collector, make composite current collector have good metal layer peeling force, conductivity and mechanical strength.

[0085] The above description is merely preferred embodiments of the present application and a description of the principles of the technology used, and those skilled in the art should understand that the utility model range involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and also covers other technical solutions formed by any combination of the above technical features or equivalent features without departing from the utility model concept, for example, the technical solutions formed by replacing the above features with the technical features disclosed in the present application (but not limited to) having similar functions.

[0086] In addition to the technical features described in the specification, the remaining technical features are known to those skilled in the art, and to highlight the innovative features of the utility model, the remaining technical features will not be described here.

Claims

1. A composite current collector, characterized in that, At least including: A substrate having a porous structure; A conductive polymer is disposed on both sides of the substrate, penetrating the porous structure; as well as A metal layer is disposed on the other side of the conductive polymer and the substrate composite side.

2. The composite current collector according to claim 1, characterized in that, The porosity of the substrate is 30%-50%, and the tensile strength of the substrate is >50MPa.

3. The composite current collector according to claim 1, characterized in that, In the substrate, the pore size of the porous structure is 3μm-100μm.

4. The composite current collector according to claim 3, characterized in that, With the total area of ​​the porous structure being 100%, the sum of the areas of pores with a diameter > 5 μm accounts for > 50%.

5. The composite current collector according to claim 1, characterized in that, The thickness of the substrate is <10μm.

6. The composite current collector according to claim 1, characterized in that, The thickness of the conductive polymer is 2μm-5μm.

7. The composite current collector according to claim 1, characterized in that, The thickness of the metal layer is 0.5μm-3μm.

8. A secondary battery, characterized in that, Includes the composite current collector as described in any one of claims 1-7.

9. An electronic device, characterized in that, Includes the secondary battery as described in claim 8.

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