METHOD FOR PRODUCING AN ACTIVE MATERIAL LAYER FOR A BATTERY, ACTIVE MATERIAL LAYER FOR A BATTERY, AND BATTERY

Abstract

A method for producing an active material layer for a battery, comprising: producing an active material layer, the active material layer containing a binder and an active material; and irradiating the active material layer with a pulsed nanosecond laser, provided that the amount of heat supplied is greater than or equal to 0.005 J / mm² 2 and less than or equal to 0.050 J / mm 2 is.

Description

BACKGROUNDTechnical area

[0001] The present disclosure relates to a method for producing an active material layer for a battery, an active material layer for a battery and a battery. State of the art

[0002] Liquid batteries that use an electrolyte solution typically employ an active material layer containing a binder and an active material.

[0003] For example, Japanese patent application Publication (JP-A) No. 2011-171020 discloses a battery with a non-aqueous electrolyte solution comprising an electrode assembly, an outer material, and a non-aqueous electrolyte solution. The electrode assembly has a positive electrode, a negative electrode, and a separator. The positive electrode has a positive electrode current collector and a positive electrode layer containing a positive electrode active material and a binder, formed on the positive electrode current collector. The negative electrode has a negative electrode current collector and a negative electrode layer containing a negative electrode active material and a binder, formed on the negative electrode current collector. The separator is inserted between the positive electrode layer and the negative electrode layer and is wound onto both the positive and negative electrodes.At least one of the positive electrode layer and the negative electrode layer has several permeation-promoting sections formed on their respective surface sides to connect both longitudinal sides (S), where the amount of binder is less than on the surface sides of other areas (R), and which promote the permeation of the non-aqueous electrolyte solution from the surface sides of the areas (R).

[0004] JP-A No. 2011-171020 discloses a method for creating areas with a low binder content on the surfaces of the electrode layers of a battery using a non-aqueous electrolyte solution, using a CW laser. However, the laser irradiation removes active materials and the like from the electrode layers, and the amount of active materials decreases, resulting in a reduction in the battery's capacity in some cases.

[0005] Furthermore, the ability of the electrolyte solution to penetrate the active material layers of the battery affects the battery's resistance. Therefore, it is desirable to reduce the battery's resistance by improving the electrolyte solution's ability to penetrate the active material layers. SHORT ADVERTISEMENT

[0006] The present disclosure was made in view of the circumstances described above, and one objective of it is to provide a method for producing an active material layer for a battery, an active material layer for a battery and a battery having the active material layer for a battery, which can reduce the resistance of the battery while suppressing a decrease in the battery capacity of the battery.

[0007] The following aspects are considered as means of addressing the issue described above. <1>

[0008] A method for producing an active material layer for a battery, which includes the following: a step in the production of an active material layer containing a binder and an active material; and an irradiation step of irradiating the active material layer with a pulsed nanosecond laser under the condition that the amount of heat supplied is greater than or equal to 0.005 J / mm² 2 and less than or equal to 0.050 J / mm 2 is. <2>

[0009] Method for producing an active material layer for a battery of <1> , wherein the irradiation step is a step of irradiation with a pulsed nanosecond laser under conditions where an output power is greater than or equal to 1.25 W and less than or equal to 5 W, and an overlap ratio is greater than or equal to 0% and less than or equal to 63%. <3>

[0010] Active material layer for a battery, which active material layer contains a binder and an active material, wherein an average particle diameter of the binder in an image of a surface obtained by EPMA mapping, obtained with staining of the binder, is larger than an average particle diameter of the binder in an image of a cross-section with a depth of 20 µm obtained by EPMA mapping. <4>

[0011] Active material layer for a battery, which active material layer contains a binder and an active material, wherein an average particle diameter of the binder in an image of a surface obtained by EPMA mapping with staining of the binder is greater than or equal to 30 µm. <5>

[0012] Battery that provides the active material layer for a battery of <3> or <4> as includes at least one positive electrode active material layer or a negative electrode active material layer.

[0013] According to the present disclosure, a method for producing an active material layer for a battery, an active material layer for a battery and a battery with the active material layer for a battery are provided, which can reduce the resistance of the battery and simultaneously suppress a decrease in the battery capacity of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Exemplary embodiments of the present invention are described in more detail on the basis of the following figures, wherein: Fig.Figure 1 is a diagram showing the results of the mass change measurement (mass loss (%)) of the active material layers before and after irradiation with pulsed nanosecond lasers in the examples and comparison examples; and Fig. Figure 2 is a diagram showing the results of the battery resistance measurement in the examples and a reference example. DETAILED DESCRIPTION

[0015] An embodiment that is an example of the present disclosure is described below. This description and the examples illustrate embodiments and do not limit the scope of the invention.

[0016] In numerical value ranges expressed stepwise in this specification, the maximum or minimum value of a given numerical value range can be substituted by the maximum or minimum value of another numerical value range expressed stepwise. Furthermore, in the numerical value ranges of this specification, the maximum or minimum value of a given numerical value range can be substituted by a value given in the examples.

[0017] Each component can contain several types of the corresponding material. When listing the quantities of the respective components in a composition, in a case where there are several types of materials corresponding to a component in the composition, the quantity of that component means the total quantity of the several types of materials present in the composition, unless otherwise specified. "Step" is not only an independent step and also includes steps that, even if this step cannot be clearly distinguished from another step, achieve the purpose pursued by that step. <Verfahren zur Herstellung einer Aktivmaterialschicht für eine Batterie>

[0018] A method for producing an active material layer for a battery, relating to an embodiment of the present disclosure, includes a step of producing an active material layer containing a binder and an active material, and an irradiation step of irradiating the active material layer with a pulsed nanosecond laser, provided that the amount of heat supplied is greater than or equal to 0.005 J / mm² 2 and less than or equal to 0.050 J / mm 2 is.

[0019] In the method for producing an active material layer for a battery according to the embodiment of the present disclosure, heat is locally applied to the surface of the active material layer by means of a pulsed nanosecond laser, wherein at this time an amount of heat supplied is greater than or equal to 0.005 J / mm². 2This process melts the binder on the surface of the active material layer due to the heat, causing it to flocculate. This ensures a reactive surface on the surface of the active material layer and provides pathways for the electrolyte solution to permeate the active material layer. As a result, the resistance of a battery incorporating this active material layer can be reduced.

[0020] Furthermore, a pulsed nanosecond laser is used as the laser that is beamed onto the surface of the active material layer, and the amount of heat supplied at the time of irradiation by the pulsed nanosecond laser is reduced to less than or equal to 0.050 J / mm². 2This means that the heat is applied locally to the surface of the active material layer by a pulsed nanosecond laser, and the overall amount of heat is suppressed. This suppresses the active material that would otherwise be removed from the layer due to laser irradiation, thus preventing the loss of active material mass. Therefore, a decrease in the battery capacity of a battery containing this active material layer is prevented.

[0021] Furthermore, the use of a pulsed nanosecond laser, which is directed onto the surface of the active material layer, suppresses the removal of the binder from the active material layer. Therefore, the adhesive strength on the active material layer is maintained, and the formation of foreign substances from the active material layer is also suppressed.

[0022] The process for producing an active material layer for a battery according to the embodiment of the present disclosure is described step by step below. - Step of creating the active material layer -

[0023] The method for producing an active material layer for a battery according to the embodiment of the present disclosure comprises a step of producing an active material layer containing a binder and an active material.

[0024] The active material layer can be either a negative electrode or a positive electrode active material layer. Both the negative electrode and positive electrode active material layers can be formed using conventionally known methods. For example, the active material layer can be formed by coating and drying a solution containing the raw materials for the active material layer.

[0025] The active material, the binder and the like are described separately below with regard to the negative electrode active material layer and the positive electrode active material layer. Negative electrode active material layer

[0026] Graphite-based carbon, such as natural graphite, synthetic graphite, amorphous coated graphite, and the like, are examples of negative electrode active materials. The proportion of graphite contained in the graphite-based carbon is greater than or equal to approximately 50 wt% and preferably greater than or equal to 80 wt%.

[0027] Examples of the binder contained in the negative electrode active material are rubbers such as styrene-butadiene copolymer (SBR) and the like, as well as vinyl halide resins such as polyvinylidene fluoride (PVdF) and the like.

[0028] The negative electrode active material layer may also contain other components such as a thickening agent or the like.

[0029] Examples of thickening agents include celluloses such as carboxymethylcellulose (CMC) and the like. Positive electrode active material layer

[0030] Examples of positive electrode active materials are lithium-nickel-cobalt-manganese complex oxides (hereafter occasionally referred to simply as "LNCM"). The simplest LNCM is represented by the general formula LiNi x Co y Mn z O2 expressed (where x, y, z in the formula 0 <x<1, 0<y<1, 0<z<1, und x+y+z=1 sind). Zusätzlich zu Li, Ni, Co und Mn kann LNCM andere additive Elemente enthalten, wie etwa andere Übergangsmetallelemente als Ni, Co, Mn und andere Hauptgruppenelemente als Li und dergleichen. LNCM hat eine geschichtete Kristallstruktur. LNCM übersteigt 50 Massen-% des gesamten Positivelektrodenaktivmaterials, und es ist gut, wenn LNCM in einer Menge von beispielsweise 80 - 100 Massen-% enthalten ist. Das Positivelektrodenaktivmaterial kann allein durch LNCM strukturiert sein.

[0031] Examples of other positive electrode active materials include lithium nickel complex oxides, lithium cobalt complex oxides, lithium nickel manganese complex oxides, and the like.

[0032] Examples of the binder contained in the positive electrode active material layer are vinyl halide resins such as polyvinylidene fluoride (PVdF) and the like.

[0033] The positive electrode active material layer can contain other components such as a conductive material or the like. Examples of conductive materials include carbon that is difficult to graphitize, carbon that is easily graphitized, such as carbon black or the like, graphite, and the like. - Irradiation step -

[0034] In the next irradiation step, a pulsed nanosecond laser is irradiated onto the active material layer, with the amount of heat supplied being greater than or equal to 0.005 J / mm². 2 and less than or equal to 0.050 J / mm 2 is.

[0035] A pulsed nanosecond laser is defined as a pulsed laser whose pulse width is greater than or equal to 1 ns and less than or equal to 500 ns. Preferably, the pulse width of the pulsed nanosecond laser is greater than or equal to 1 ns and less than or equal to 100 ns. Amount of heat supplied

[0036] The amount of heat supplied by the pulsed nanosecond laser, which is directed onto the active material layer in the irradiation step, is greater than or equal to 0.005 J / mm². 2 and less than or equal to 0.050 J / mm 2 .

[0037] By ensuring that the amount of heat supplied is greater than or equal to 0.005 J / mm 2If the binder on the surface of the active material layer melts and flocculates, pathways for the permeation of the electrolyte solution into the active material layer are ensured. This reduces the resistance of the battery to the active material layer. Furthermore, because the amount of heat supplied is less than or equal to 0.050 J / mm², 2 This suppresses the removal of the active material from the active material layer due to laser irradiation and suppresses a decrease in the battery capacity of the battery with the active material layer.

[0038] The minimum value of the supplied heat quantity is preferably greater than or equal to 0.010 J / mm². 2 , and even more strongly preferred to be greater than or equal to 0.015 J / mm² 2 On the other hand, the maximum value of the heat input is preferably less than or equal to 0.040 J / mm². 2 , and even more strongly preferred to be less than or equal to 0.030 J / mm²2 .

[0039] The amount of heat supplied to the pulsed nanosecond laser can be controlled, for example, by adjusting the output power and the overlap ratio. Output power

[0040] From the perspective of reducing battery resistance while simultaneously suppressing a decrease in battery capacity, the output power of the pulsed nanosecond laser is preferably greater than or equal to 1.25 W and less than or equal to 5.00 W, and more preferably greater than or equal to 1.50 W and less than or equal to 4.50 W, and even more preferably greater than or equal to 2.00 W and less than or equal to 3.50 W. overlap ratio

[0041] From the perspective of reducing battery resistance while simultaneously suppressing a decrease in battery capacity, the overlap ratio at the time of irradiation with the pulsed nanosecond laser is preferably greater than or equal to 0% and less than or equal to 63%, and more preferably greater than or equal to 0% and less than or equal to 55%, and even more preferably greater than or equal to 0% and less than or equal to 30%.

[0042] The overlap ratio refers to the proportion of the surface area of ​​the regions where the pulsed nanosecond laser is irradiated in an overlapping manner, and is expressed by the following formula. (Regions where the laser is irradiated overlappingly) / ((Regions where the laser is irradiated overlappingly)+(Regions where the Lasernight is irradiated overlappingly))

[0043] A pulsed nanosecond laser is a pulsed laser with a pulse width in the nanosecond range. Through repeated irradiation within a short period, during which the laser's irradiation position is slightly shifted, the laser irradiates the entire target area. An overlapping irradiation area is one where the laser irradiates in such a way that it overlaps the previously irradiated area because the movement of the irradiation position is minimal during repeated irradiation. For example, if the irradiation is repeated without moving the irradiation position, the overlap ratio is 100%.In a case where irradiation is repeated while the irradiation position is moved in such a way that the area irradiated by the single laser irradiation is missed, the ratio is 0%. The ratio between overlap and irradiation can be controlled, for example, by adjusting the movement distance or similar factors at the time of the repeated laser irradiation. <Aktivmaterialschicht für Batterie> - First active material layer -

[0044] In the present disclosure, an active material layer for a battery, relating to a first embodiment (simply called the "first active material layer"), comprises a binder and an active material, and the average particle diameter of the binder in an image of the surface obtained by EPMA mapping, which is obtained by staining the binder, is larger than the average particle diameter of the binder in an image of a cross-section with a depth of 20 µm, which is obtained by EPMA mapping.

[0045] If the average particle diameter [A] of the binder at the surface of the active material layer is larger than the average particle diameter [B] of the binder in a cross-section at a depth of 20 µm from the surface, this means that the binder flocculates at the surface of the active material layer. This ensures the reaction surface at the surface of the active material layer, guarantees the permeation pathways of the electrolyte solution into the active material layer, and reduces the resistance of the battery with this active material layer.

[0046] It should be noted that the first active material layer can be obtained, for example, by the above-described method for producing an active material layer for a battery according to an embodiment of the present disclosure. - Second active material layer -

[0047] In the present disclosure, an active material layer for a battery, relating to a second embodiment (simply called the "second active material layer"), comprises a binder and an active material, and the average particle diameter of the binder in an image of the surface obtained by EPMA mapping, which is obtained by staining the binder, is greater than or equal to 30 µm.

[0048] If the average particle diameter [A] of the binder at the surface of the active material layer is greater than or equal to 30 µm, this means that the binder flocculates at the surface of the active material layer. This ensures the reaction surface at the surface of the active material layer, guarantees the permeation pathways for the electrolyte solution into the active material layer, and can thereby reduce the resistance of the battery with this active material layer.

[0049] In the second active material layer, the average particle diameter [A] of the binder at the surface is greater than or equal to 30 µm, preferably greater than or equal to 40 µm, and more preferably greater than or equal to 45 µm. Note that the maximum value of the average particle diameter [A] of the binder is, for example, preferably less than or equal to 100 µm, and more preferably less than or equal to 70 µm.

[0050] It should be noted that the second active material layer can be obtained, for example, by the above-described method for producing an active material layer for a battery according to an embodiment of the present disclosure.

[0051] The method for measuring the average particle diameter [A] of the binder at the surface of the active material layer is described here.

[0052] First, the active material layer is stained according to the binder it contains (e.g., with osmium (Os)). An EPMA (electron probe microanalysis) image of the active material layer's surface is then acquired after staining. From the resulting mapping image, the highest luminance data (10%) are calculated, and binarization is performed by setting these luminance data as the threshold. The particle diameters of the binder particles (i.e., the lengths of the longest segments in the image of the target binder particles) are then measured from the post-binarization image. This measurement is performed on 20 binder particles, and the arithmetic mean of these measurements is used as the average particle diameter.

[0053] Note that when measuring the average particle diameter [B] of the binder in a cross-section at a depth of 20 µm from the surface, the cross-section at a depth of 20 µm from the surface is exposed by a method such as cutting or the like, and then the average particle diameter is determined in the same way as the method described above for measuring the average particle diameter [A]. <batterie>

[0054] A battery relating to an embodiment of the present disclosure has the first active material layer or second active material layer described above as at least one of the positive electrode active material layer and negative electrode active material layer. The battery has, for example, a negative electrode, a positive electrode, a separator, and an electrolyte solution. (Electrolyte solution) Solvent

[0055] The electrolyte solution contains a solvent (a non-aqueous solvent) and an electrolyte.

[0056] Examples of the aqueous solvent are N,N-Diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide (DEME), 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI), 1-Ethyl-2,3-dimethylimidazolium bis(fluorosulfonyl)imide (DEMI-FSI) and the like. electrolyte

[0057] Lithium salts are examples of the electrolyte in electrolyte solutions. Examples of lithium salts include lithium bis(fluorosulfonyl)imide (LiFSI), LiPF6 (lithium hexafluorophosphate), lithium tetrafluoroborate (LiBF4), Li[N(CF3SO2)2], and the like.

[0058] The amount of electrolyte can be, for example, 1.0 - 2.0 mol / L, preferably 1.0 - 1.5 mol / L.

[0059] In addition to the solvent and electrolyte, the electrolyte solution may contain various additives such as thickeners, film formers, gas generators, and the like. The electrolyte is typically a non-aqueous solution that is liquid at normal temperatures (e.g., 25 ± 10 °C). The electrolyte solution typically assumes a liquid state in the operating environments of batteries (e.g., at temperatures from -20 to +60 °C). (Negative electrode)

[0060] The negative electrode has, for example, a negative electrode current collector and a negative electrode active material layer attached to the negative electrode current collector. A conductive element made of a highly conductive metal (e.g., copper) is suitable as a negative electrode current collector. For example, the first or second active material layer described above is used as the negative electrode active material layer. (Positive electrode)

[0061] The positive electrode has, for example, a positive electrode current collector and a positive electrode active material layer attached to the positive electrode current collector. A conductive element made of a highly conductive metal (e.g., aluminum) is suitable as the positive electrode current collector. The first or second active material layer described above is used, for example, as the positive electrode active material layer. (Separator)

[0062] The separator is an electrically insulating, porous film. It electrically insulates the positive and negative electrodes. The separator can have a thickness of, for example, 5–30 µm. It can be made of, for example, a porous polyethylene (PE) film, a porous polypropylene (PP) film, or similar materials. The separator can have a multilayer structure. For example, it can consist of a porous PP film, a porous PE film, and another porous PP film layered on top of each other in that order. The separator can have a heat-resistant layer on its surface. This heat-resistant layer contains a heat-resistant material. Examples of heat-resistant materials include metal oxide particles such as aluminum oxide, high-melting-point resins such as polyimide, and similar materials. (Applications)

[0063] Examples of battery applications include, for example, the energy source of a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), an electric vehicle (BEV), or the like. EXAMPLES

[0064] The present disclosure is described below by means of examples, but is in no way limited to these examples. Note that in the following explanation, “parts” and “%” are all based on mass unless otherwise stated. <Beispiele 1 bis 4, Vergleichsbeispiele 1 und 2>

[0065] In the examples and comparative examples, the surfaces of active material layers with the following compositions were irradiated with a laser, whereby the amount of heat supplied was changed by adjusting the output power and the overlap ratio of the irradiated pulsed nanosecond laser according to Table 1. (Irradiation conditions) a) Laser pulse duration: 50 ns, output power: 2.5 W - 5 W, overlap ratio: 0% - 63% b) Composition of the active material layer: Negative electrode active material = graphite, binder = styrene-butadiene copolymer (SBR), thickener = carboxymethylcellulose (CMC), conductive material: carbon nanotubes (CNTs) [Table 1] Example 1 Example 2 Example 3 Example 4 See example 1. See example 2. Output power [W] 2,5 2,5 2,5 2,5 3,75 5 Overlap ratio (%) 0 25 50 63 63 63 Heat supplied [J / mm] 2 0,005 0,01 0,022 0,04 0,06 0,08 <bewertung>(1) Mass loss

[0066] In each of the examples and comparison examples, the mass change (mass loss (%)) of the active material layer was measured before and after irradiation with the pulsed nanosecond laser. The results are presented in Fig. 1 is represented as a diagram.

[0067] As the diagram in Fig. Figure 1 shows that the results in Example 1 (amount of heat supplied: 0.005 J / mm²) were... 2 ), Example 2 (0.01 J / mm²) 2 ), Example 3 (0.022 J / mm²) 2 ) and example 4 (0.04 J / mm²) 2 ) the mass loss of the active material layer was kept to less than or equal to 6%, whereas in comparative example 1 (supplied heat quantity: 0.06 J / mm²) 2 ) and comparison example 2 (0.08 J / mm²) 2 ) the mass loss of the active material layer was significantly above 6%. (2) Battery resistance

[0068] Batteries were fabricated using the active material layers from Example 1 and Example 2, exhibiting low mass losses, and their battery resistances were tested. Additionally, as a reference example (Ref), a battery resistance test was performed in the same manner using an active material layer whose surface had not been irradiated with a pulsed nanosecond laser. The percentages relative to the reference example (Ref) are shown in Fig. 2. The results of the evaluation are graphically presented and illustrated.

[0069] It should be noted that the structure of the batteries in the battery resistance tests is a layered cell battery (positive electrode: 45 mm x 47 mm, negative electrode: 47 mm x 49 mm).

[0070] As shown in the diagram in Fig. As can be seen in Figure 2, the battery resistance in Example 1 and Example 2 could be reduced compared to the reference example (Ref). (3) Average particle diameter of the binder

[0071] With reference to Example 1 and the reference example (Ref) described above, the average particle diameter of the binder was measured in an image of the surface obtained by EPMA mapping with binder staining.

[0072] The active material layers in Example 1 and the reference example were stained with osmium (Os), and EPMA (electron probe microanalysis) mapping images of the active material layer surfaces were generated after staining. From the mapping images, the luminance data for the highest 10% were calculated, and binarization was performed by setting these luminance data as the threshold. The particle diameters (lengths of the longest segments) of the binder particles (SBR) from the post-binarization image were measured on 20 binder particles, and the arithmetic mean of these measurements was used as the average particle diameter. The results are as follows. - Average particle diameter - Example 1: 35 µm Reference example (Ref): 17 µm QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2011-171020 [0003, 0004]< / bewertung> < / batterie>

Claims

[1] A method for producing an active material layer for a battery, the method comprising: Producing an active material layer, wherein the active material layer contains a binder and an active material; and Irradiation of the active material layer with a pulsed nanosecond laser under a condition that the amount of heat supplied is greater than or equal to 0.005 J / mm 2 and less than or equal to 0.050 J / mm 2 is. [2] The method according to claim 1, wherein the irradiating step includes irradiating a pulsed nanosecond laser under conditions where the output power is greater than or equal to 1.25 W and less than or equal to 5 W and an overlap ratio is greater than or equal to 0% and less than or equal to 63%. [3] An active material layer for a battery, the active material layer containing a binder and an active material, wherein an average particle diameter of the binder in an image of a surface obtained by EPMA mapping with coloring of the binder is larger than an average particle diameter of the binder in an image of a cross section with a depth of 20 µm obtained by EPMA mapping. [4] An active material layer for a battery, the active material layer containing a binder and an active material, wherein an average particle diameter of the binder in an image of a surface obtained by EPMA mapping obtained with coloring of the binder is greater than or equal to 30 µm. [5] A battery comprising the active material layer for a battery according to claim 3 or claim 4 as a positive electrode active material layer and / or as a negative electrode active material layer.

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