Cathode electrode comprising multiple particle size distributions manufactured using solvent-free process

Abstract

A cathode electrode for a battery cell includes a cathode current collector and a cathode active material layer disposed on the cathode current collector. The cathode active material layer includes a first cathode active material having a first secondary particle size distribution, a second cathode active material having a second secondary particle size distribution different from the first secondary particle size distribution, a conductive additive, and a fibril binder.

Description

Technical Field

[0001] The present disclosure relates to battery pack cells, and more particularly to cathode electrodes having a mixed particle size for a cathode electrode fabricated using a solventless method. Background Art

[0002] The information provided in this section is intended to generally introduce the background of the present disclosure. To the extent that the work currently attributed to the inventors is described in this section, and aspects of the specification that may not otherwise be determined to be prior art at the time of filing, are not admitted to be prior art for the present disclosure, either expressly or by implication.

[0003] The present disclosure relates to battery pack cells, and more particularly to cathode electrodes having a mixed particle size for a cathode electrode fabricated using a solventless method.

[0004] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, include one or more electric motors and a battery pack system including one or more battery pack cells, modules, and / or battery packs. A power control system is used to control the charging and / or discharging of the battery pack system during charging and / or driving.

[0005] A battery pack cell includes a cathode electrode, an anode electrode, and a separator. The cathode electrode includes a cathode active material layer disposed on a cathode current collector. The anode electrode includes an anode active material layer disposed on an anode current collector. Summary of the Invention

[0006] A cathode electrode for a battery pack cell includes a cathode current collector and a cathode active material layer disposed on the cathode current collector. The cathode active material layer includes a first cathode active material having a first secondary particle size distribution, a second cathode active material having a second secondary particle size distribution different from the first secondary particle size distribution, a conductive additive, and a fibrillating binder.

[0007] In other features, the first secondary particle size distribution includes a D50 secondary particle size in the range of 10 μm to 20 μm. The first secondary particle size distribution includes a D90 secondary particle size in the range of 15 μm to 30 μm. The first cathode active material and the second cathode active material include secondary particles.

[0008] In other features, the first cathode active material includes secondary particles and the second cathode active material includes single crystals. The second secondary particle size distribution includes a D50 secondary particle size in the range of 2 μm to 8 μm. The second cathode active material accounts for 5 wt% to 40 wt% of the cathode active material in the cathode active material layer.

[0009] Among other features, the cathode active material layer comprises a cathode active material in the range of 90 wt% to 96.5 wt%, a conductive additive in the range of 2 wt% to 5 wt%, and a fibril binder in the range of 1.5 wt% to 5 wt%. Second active material particles fill the spaces between the first active material particles, and more than 90 wt% of the second active material particles are connected to clusters comprising the fibril binder and the conductive additive.

[0010] Among other features, the fibril binder comprises polytetrafluoroethylene (PTFE). The cathode active material layer has a D50 particle size in the range of 6 μm to 16 μm, a D90 particle size in the range of 20 μm to 30 μm, and a specific surface area in the range of 0.6 to 1.3 m 2 / g.

[0011] A method for manufacturing a cathode electrode for a battery pack cell, comprising a) generating a mixture by mixing a first cathode active material having a first particle size distribution, a second cathode active material having a second particle size distribution different from the first particle size distribution, and a conductive additive; b) adding a fibril binder to the mixture; c) subjecting the mixture to high shear forces to fibrillate the fibril binder; d) calendering the mixture to produce a cathode active material layer; and e) laminating the cathode active material layer onto a cathode current collector to form a cathode electrode.

[0012] Among other features, a) comprises a1) mixing the first cathode active material and the second cathode active material; and a2) adding the conductive additive to the first cathode active material and the second cathode active material.

[0013] Among other features, a) comprises a1) mixing the first cathode active material with the conductive additive; a2) mixing the second cathode active material with the conductive additive; and a3) mixing the first cathode active material with the conductive additive and the second cathode active material with the conductive additive.

[0014] Among other features, the first secondary particle size distribution comprises a D50 particle size in the range of 10 μm to 20 μm. The first secondary particle size distribution comprises a D90 particle size in the range of 15 μm to 30 μm. The first cathode active material and the second cathode active material comprise secondary particles.

[0015] Among other features, the first cathode active material comprises secondary particles and the second cathode active material comprises single crystals.

[0016] Among other features, the second secondary particle size distribution comprises a D50 particle size in the range of 2 μm to 8 μm, and the second secondary particle size distribution comprises a D90 particle size in the range of 5 μm to 10 μm.

[0017] Among other features, the second cathode active material accounts for 5 wt% to 40 wt% of the cathode active material in the cathode active material layer.

[0018] Among other features, the cathode active material layer contains a cathode active material in the range of 90 wt% to 96.5 wt%, a conductive additive in the range of 2 wt% to 5 wt%, and a fibrillar binder in the range of 1.5 wt% to 5 wt%. The cathode active material layer has a D50 particle size in the range of 6 μm to 16 μm, a D90 particle size in the range of 20 μm to 30 μm, and a specific surface area in the range of 0.6 to 1.3 m 2 / g.

[0019] The present invention discloses the following solutions:

[0020] Solution 1. A cathode electrode for a battery pack cell, comprising:

[0021] a cathode current collector; and

[0022] a cathode active material layer disposed on the cathode current collector,

[0023] wherein the cathode active material layer contains a first cathode active material having a first secondary particle size distribution, a second cathode active material having a second secondary particle size distribution different from the first secondary particle size distribution, a conductive additive, and a fibrillar binder.

[0024] Solution 2. The cathode electrode according to Solution 1, wherein the first secondary particle size distribution includes a D50 secondary particle size in the range of 10 μm to 20 μm.

[0025] Solution 3. The cathode electrode according to Solution 2, wherein the first secondary particle size distribution includes a D90 secondary particle size in the range of 15 μm to 30 μm.

[0026] Solution 4. The cathode electrode according to Solution 1, wherein the first cathode active material and the second cathode active material comprise secondary particles.

[0027] Solution 5. The cathode electrode according to Solution 1, wherein the first cathode active material comprises secondary particles, and the second cathode active material comprises single crystals.

[0028] Solution 6. The cathode electrode according to Solution 2, wherein the second secondary particle size distribution includes a D50 secondary particle size in the range of 2 μm to 8 μm.

[0029] Solution 7. The cathode electrode according to Solution 1, wherein the second cathode active material accounts for 5 wt% to 40 wt% of the cathode active material in the cathode active material layer.

[0030] Embodiment 8. The cathode electrode according to Embodiment 1, wherein the cathode active material layer comprises a cathode active material in the range of 90 wt% to 96.5 wt%, a conductive additive in the range of 2 wt% to 5 wt%, and a fibril binder in the range of 1.5 wt% to 5 wt%.

[0031] Embodiment 9. The cathode electrode according to Embodiment 1, wherein the second active material particles fill the space between the first active material particles, and more than 90 wt% of the second active material particles are connected to clusters comprising the fibril binder and the conductive additive.

[0032] Embodiment 10. The cathode electrode according to Embodiment 1, wherein the fibril binder comprises polytetrafluoroethylene (PTFE).

[0033] Embodiment 11. The cathode electrode according to Embodiment 1, wherein the cathode active material layer has a D50 particle size in the range of 6 μm to 16 μm, a D90 particle size in the range of 20 μm to 30 μm, and a specific surface area in the range of 0.6 to 1.3 m 2 / g.

[0034] Embodiment 12. A method for manufacturing a cathode electrode for a battery pack cell, comprising:

[0035] a) generating a mixture by mixing a first cathode active material having a first particle size distribution, a second cathode active material having a second particle size distribution different from the first particle size distribution, and a conductive additive,

[0036] b) adding a fibril binder to the mixture;

[0037] c) applying high shear force to the mixture to fibrillate the fibril binder;

[0038] d) calendering the mixture to produce a cathode active material layer; and

[0039] e) laminating the cathode active material layer onto a cathode current collector to form a cathode electrode.

[0040] Embodiment 13. The method according to Embodiment 12, wherein a) comprises:

[0041] a1) mixing the first cathode active material and the second cathode active material; and

[0042] a2) adding the conductive additive to the first cathode active material and the second cathode active material.

[0043] Embodiment 14. The method according to Embodiment 12, wherein a) comprises:

[0044] a1) mixing the first cathode active material with the conductive additive;

[0045] a2) Mix the second cathode active material with a conductive additive; and

[0046] a3) Mix the first cathode active material with a conductive additive and the second cathode active material with a conductive additive.

[0047] Aspect 15. The method according to Aspect 12, wherein:

[0048] The first secondary particle size distribution includes a D50 particle size in the range of 10 μm to 20 μm, and

[0049] The first secondary particle size distribution includes a D90 particle size in the range of 15 μm to 30 μm.

[0050] Aspect 16. The method according to Aspect 12, wherein the first cathode active material and the second cathode active material comprise secondary particles.

[0051] Aspect 17. The method according to Aspect 12, wherein the first cathode active material comprises secondary particles and the second cathode active material comprises single crystals.

[0052] Aspect 18. The method according to Aspect 15, wherein:

[0053] The second secondary particle size distribution includes a D50 particle size in the range of 2 μm to 8 μm, and

[0054] The second secondary particle size distribution includes a D90 particle size in the range of 5 μm to 10 μm.

[0055] Aspect 19. The method according to Aspect 12, wherein the second cathode active material accounts for 5 wt% to 40 wt% of the cathode active material in the cathode active material layer.

[0056] Aspect 20. The method according to Aspect 12, wherein:

[0057] The cathode active material layer comprises a cathode active material in the range of 90 wt% to 96.5 wt%, a conductive additive in the range of 2 wt% to 5 wt%, and a fibrillar binder in the range of 1.5 wt% to 5 wt%, and

[0058] The cathode active material layer has a D50 particle size in the range of 6 μm to 16 μm, a D90 particle size in the range of 20 μm to 30 μm, and a specific surface area in the range of 0.6 to 1.3 m 2 / g.

[0059] From the detailed description, the claims, and the drawings, further applicable fields of the present disclosure will become apparent. The detailed description and specific examples are only intended to illustrate and are not intended to limit the scope of the present disclosure. Description of the Drawings

[0060] The present disclosure will be more fully understood through the detailed description and the drawings, wherein:

[0061] Figure 1 is a side cross-sectional view of an example of a battery cell of a battery pack including a cathode electrode, an anode electrode, and a separator according to the present disclosure;

[0062] Figure 2 is a side cross-sectional view of an example of a cathode electrode according to the present disclosure;

[0063] Figures 3A to 5B is a scanning electron microscope image of an example of various cathode active material layers;

[0064] Figure 6A and Figure 6B illustrates an example of a cathode active material layer including cathode active materials having different particle size distributions according to the present disclosure;

[0065] Figures 7 to 9 is a flowchart of an example of a method for manufacturing a cathode electrode having different particle size distributions according to the present disclosure;

[0066] Figure 10A and Figure 10B are scanning electron microscope images of examples of cathode active material layers having large and small secondary particle size distributions according to the present disclosure;

[0067] Figure 11 shows Figure 12A and Figure 12B a graph of the percentage of density distribution changing with the secondary particle size in the examples of

[0068] Figure 12A and Figure 12B are scanning electron microscope images of an example of a cathode active material layer having large secondary particles and small single crystals according to the present disclosure; and

[0069] Figure 13 shows Figure 12A and Figure 12B a graph of the percentage of density distribution changing with the secondary particle size in the examples of

[0070] In the drawings, reference numerals may be reused to identify similar and / or identical elements. Detailed Description

[0071] Although the battery cells according to the present disclosure are shown in the context of an electric vehicle, the battery cells can be used in stationary applications and / or other applications.

[0072] The present disclosure relates to a cathode electrode and a method of manufacturing a cathode electrode using a solvent-free manufacturing method. The present disclosure relates to the adhesion mechanism of a cathode electrode based on fibrillar binders and the particle size distribution of cathode active materials used in a cathode active material layer.

[0073] When using a solvent-free manufacturing method, a cathode active material having a polydisperse particle size distribution is optimal. The cathode electrodes described herein use a cathode active material having at least two different mixed particle size distributions. More specifically, the cathode active material of the cathode electrode includes large secondary particles combined with small secondary particles or single crystals.

[0074] The binder fibrillates to produce a fibril network. The combination of the fibril network and the particle size variation improves the performance of the cathode electrode (e.g., carbon distribution uniformity and mechanical properties). The large secondary particles combined with small secondary particles and / or single crystals can be prepared using the same type of cathode active material or a blend including two or more types of cathode active materials.

[0075] Now referring to Figure 1 , the battery cell 10 includes C cathode electrodes 20, A anode electrodes 40, and S separators 32 arranged in a battery cell stack 12 in a predetermined order, where C, S, and A are integers greater than zero. The battery cell stack 12 is arranged in a housing 50. The C cathode electrodes 20-1, 20-2,... and 20-C include a cathode active material layer 24 arranged on one or both sides of a cathode current collector 26.

[0076] The A anode electrodes 40-1, 40-2,... and 40-A include an anode active material layer 42 arranged on one or both sides of an anode current collector 46. In some examples, the cathode active material layer 24 and / or the anode active material layer 42 contains a mixture of one or more active materials, one or more conductive additives, and / or one or more binder materials applied to the current collector. During the charge / discharge process, the A anode electrodes 40 and the C cathode electrodes 20 exchange lithium ions.

[0077] In some instances, the cathode current collector 26 and / or the anode current collector 46 includes a metal foil, a metal mesh, a perforated metal, a three-dimensional (3D) metal foam, and / or an expanded metal. In some instances, the current collector is made of one or more materials selected from copper, stainless steel, brass, bronze, zinc, aluminum, and / or their alloys. The external tabs 28 and 48 are connected to the current collectors of the cathode electrode and the anode electrode, respectively, and may be disposed on the same side or different sides of the battery module stack 12. The external tabs 28 and 48 are connected to the terminals of the battery module battery. In some instances, the battery module batteries are stacked or wound. In some instances, the housing includes a prismatic housing, a pouch housing, or a cylindrical housing.

[0078] Now referring to Figure 2 , C cathode electrodes 20 are shown in more detail. The cathode active material layer 24 of the C cathode electrodes 20 includes a cathode active material 62, a conductive additive 64, and a binder 66. The large secondary particles and small secondary particles and / or single crystals may include the same cathode active material or two or more types of cathode active materials.

[0079] When using the wet method, the binder is uniform and coats the cathode active material. The binder typically accounts for 2 wt% to 5 wt% of the cathode active material layer. The wet method produces a cathode electrode with blocked ion conduction, blocked electron conduction, and / or high conduction tortuosity.

[0080] When using the dry method, the binder is fibrillated and does not necessarily coat the surface of the cathode active material. The binder typically accounts for no more than 2 wt% of the cathode active material layer. The dry method results in good ion and electron conductivity and low conduction tortuosity.

[0081] Now referring to Figures 3A to 5B , scanning electron microscope images of different types of cathode active material layers are shown. In Figure 3A and Figure 3B , the cathode active material layer contains only large secondary particles of the cathode active material. When using large secondary particles, the cathode electrode film is soft due to the long fibrils, but the distribution of the conductive additive is poor.

[0082] In Figure 4A and Figure 4B , the cathode electrode includes only small secondary particles of the cathode active material. When using small secondary particles, the cathode electrode film is brittle due to the short fibrils, and the distribution of the conductive additive is good.

[0083] In Figure 5A and Figure 5BAmong them, the cathode electrode includes large secondary particles and small secondary particles or single crystal particles of the cathode active material. When using bimodal secondary particles of the cathode active material, the cathode electrode film has good film-forming processing performance and good distribution of conductive additives. It can be seen from the above that the particle size affects the PTFE fibril network and the uniformity of carbon distribution.

[0084] Now refer to Figure 6A and Figure 6B , the cathode active material includes N different particle size distributions (where N≥2). The smaller active material particles fill the space between the larger secondary particles. In some examples, >90 wt% of the smaller active material particles are tightly connected to the PTFE / conductive additive clusters to form a fibril structure. In Figure 6A Among them, the larger cathode active material particles include secondary particles, and the smaller cathode active material includes smaller secondary particles. In Figure 6B Among them, the larger cathode active material particles include secondary particles, and the smaller cathode active material includes single crystals.

[0085] The cathode electrode contains a first cathode active material (having a first particle size distribution), a second cathode active material (having a second particle size distribution), a conductive additive (e.g., conductive carbon), and a PTFE binder. In some examples, the D50 particle size of the first cathode active material is in the range of 10 μm to 20 μm. In some examples, the D90 particle size of the first cathode active material is in the range of 15 μm to 30 μm.

[0086] In some examples, the second cathode active material has a second particle size distribution. The second cathode active material contains at least one of secondary particles and single crystals. In some examples, the D50 particle size of the second cathode active material is in the range of 2 μm to 8 μm. In some examples, the D90 particle size of the second cathode active material is in the range of 5 μm to 10 μm.

[0087] In some examples, the second cathode active material accounts for 5 wt% to 40 wt% of the cathode active material. In some examples, the dry electrode contains 90 wt% to 96.5 wt% of the cathode active material, 2 wt% to 5 wt% of the conductive additive, and 1.5 wt% to 5 wt% of the fibril binder. The electrode material mixture (active material, conductive filler, and binder) has a D50 particle size in the range of 6 μm to 16 μm, a D90 particle size in the range of 20 μm to 30 μm, and a specific surface area in the range of 0.6 to 1.3 m 2 / g.

[0088] In some instances, the first cathode active material and the second cathode active material include the same cathode active material. In some instances, the first cathode active material and / or the second cathode active material include different cathode active materials. In some instances, the first cathode active material includes a blend of cathode active materials (or a single type of cathode active material), and the second cathode active material includes a blend of cathode active materials (or a single type of cathode active material). In some instances, the first cathode active material includes a first type of cathode active material and the second cathode active material includes a second type of cathode active material.

[0089] Now referring to Figures 7 to 9 , various examples of a method for manufacturing a cathode electrode are shown. In Figure 7 , at 210, a first cathode active material having a first particle size distribution, a second cathode active material having a second particle size distribution, and a conductive additive are mixed. At 214, PTFE powder is added. At 218, high-shear fibrillation is performed to fibrillate the binder. At 222, the cathode active material is calendered (pressed and / or heated one or more times) to form a self-standing cathode active material layer. At 226, the cathode active material layer is laminated onto a cathode current collector.

[0090] In Figure 8 , at 230, a first cathode active material having a first particle size distribution and a second cathode active material having a second particle size distribution are mixed. At 234, a conductive additive is added to the mixture, and then the method proceeds to steps 214 to 226.

[0091] In Figure 9 , at 240, a first cathode active material having a first particle size distribution is mixed with a conductive additive. At 244, a second cathode active material having a first secondary particle size distribution is mixed with a conductive additive at 244. At 248, the first and second cathode active material mixtures (including the conductive additive) are mixed, and then the method proceeds to steps 214 to 226.

[0092] Now referring to Figures 10A to 11 , an example including a cathode active material having larger secondary particles and smaller secondary particles is shown. In this example, the first cathode active material having a first particle size distribution accounts for 80 wt% of the cathode active material. In this example, the second cathode active material having a second particle size distribution accounts for 20 wt% of the cathode active material. The surface area is 0.789 m 2 / g. The secondary particle size includes D v (0) = 0.216 μm, D v (5) = 2.91 μm, D v ( 10 ) = 5.94 μm, Dv D(50) = 12.6 μm v D(90) = 21.8 μm, and D v D(100) = 143 μm.

[0093] Now referring to Figures 12A to 13 , an example including a cathode active material having larger secondary particles and single crystals is shown. The surface area is 1.06 m 2 / g. The secondary particle size and single crystals include D v D(0) = 0.280 μm, D v D(5) = 1.73 μm, D v D(10) = 2.97 μm, D v D(50) = 11.1 μm, D v D(90) = 22.9 μm, and D v D(100) = 97.6 μm.

[0094] The foregoing description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure may be implemented in a variety of forms. Thus, although the disclosure includes specific examples, the true scope of the disclosure should not be so limited because other modifications will become apparent upon study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be performed in a different order (or concurrently) without altering the principles of the disclosure. Additionally, although the embodiments are described above as having certain features, any one or more of the features described with respect to any one embodiment of the disclosure may be implemented in any other embodiment and / or combined with the features of any other embodiment, even if not explicitly described in combination. In other words, the described embodiments are not mutually exclusive, and the interchanging of one or more of the embodiments is still within the scope of the disclosure.

[0095] Various terms are used to describe the spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.), including "connected", "joined", "coupled", "adjacent", "next to", "on top of", "on", "under", and "disposed". Unless explicitly described as "direct", when the relationship between a first element and a second element is described in the foregoing disclosure, the relationship can be a direct relationship in which no other intermediate element exists between the first element and the second element, or an indirect relationship in which one or more intermediate elements exist between the first element and the second element (spatially or functionally). The phrase "at least one of A, B, and C" as used herein should be construed to mean a logical (A or B or C) using non-exclusive logical OR and should not be construed to mean "at least one of A, at least one of B, and at least one of C".

[0096] In the drawings, the direction of the arrow indicated by the arrow generally demonstrates the flow of information (such as data or explanations) related to the illustration. For example, when component A and component B exchange various information but the information transmitted from component A to component B is related to the illustration, the arrow can point from component A to component B. Such a one-way arrow does not mean that no other information is transmitted from component B to component A. In addition, for the information transmitted from component A to component B, component B can send a request for that information or receive an acknowledgment from component A.

Claims

1. A cathode electrode for a battery cell of a battery pack, comprising: A cathode current collector; And A cathode active material layer disposed on the cathode current collector, Wherein the cathode active material layer comprises a first cathode active material having a first secondary particle size distribution, a second cathode active material having a second secondary particle size distribution different from the first secondary particle size distribution, a conductive additive, and a fibrillar binder.

2. The cathode electrode according to claim 1, wherein the first secondary particle size distribution comprises a D50 secondary particle size in the range of 10 μm to 20 μm.

3. The cathode electrode according to claim 2, wherein the first secondary particle size distribution comprises a D90 secondary particle size in the range of 15 μm to 30 μm.

4. The cathode electrode according to claim 1, wherein the first cathode active material and the second cathode active material comprise secondary particles.

5. The cathode electrode according to claim 1, wherein the first cathode active material comprises secondary particles and the second cathode active material comprises single crystals.

6. The cathode electrode according to claim 2, wherein the second secondary particle size distribution comprises a D50 secondary particle size in the range of 2 μm to 8 μm.

7. The cathode electrode according to claim 1, wherein the second cathode active material accounts for 5 wt% to 40 wt% of the cathode active material in the cathode active material layer.

8. The cathode electrode according to claim 1, wherein the cathode active material layer comprises a cathode active material in the range of 90 wt% to 96.5 wt%, a conductive additive in the range of 2 wt% to 5 wt%, and a fibrillar binder in the range of 1.5 wt% to 5 wt%.

9. The cathode electrode according to claim 1, wherein the second active material particles fill the spaces between the first active material particles, and more than 90 wt% of the second active material particles are connected to clusters comprising the fibrillar binder and the conductive additive.

10. The cathode electrode according to claim 1, wherein the fibrillar binder comprises polytetrafluoroethylene (PTFE).

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