Electrode for battery, battery, and method for manufacturing electrode

Abstract

To provide an electrode capable of improving a structure efficiency of a battery.SOLUTION: An electrode for a battery, comprises: a lamination body containing an active material layer and a collector; and a sealing part that covers an end part front surface of the lamination body. The lamination body includes: two opposite main surfaces; and an end surface as a front surface of the two main surfaces. The end part front surface is formed by an end surface, and an adjacent contact surface as a part where is adjacent to the end surface in each of the two main surfaces. The adjacent contact surface includes an unevenness. The sealing part is formed by: a first sealing part that covers the end surface; and a second sealing part that covers at least one part of the adjacent contact surface. The second sealing part is existed in a concave part in the unevenness of the adjacent contact surface, and does not have a part that is higher than a highest position in the unevenness, and the first sealing part and the second sealing part are connected.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an electrode for a battery, a battery, and a method for manufacturing the electrode.

Background Art

[0002] Japanese Patent No. 6729236 (Patent Document 1) discloses that in a method for manufacturing a laminated all-solid-state battery, in order to prevent short circuits and the like, an insulating coating liquid is applied to the end portion of a laminate composed of a solid electrolyte layer, an active material layer, and a current collector layer to seal the end portion of the laminate (form an insulating sealing portion at the end portion of the laminate).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for improving the structural efficiency (capacity per unit volume) of a battery. For example, when a sealing portion material (insulating coating liquid) is applied to the end portion of a laminate (i.e., an electrode) composed of an active material layer, a current collector layer, and a solid electrolyte layer, usually, an insulating resin protrusion occurs in the stacking direction. Therefore, in a laminated battery formed by laminating the laminate (electrode), an insulating resin (sealing portion) may be interposed between the electrodes, which may increase the thickness of the battery. An increase in the thickness of the battery results in a decrease in the structural efficiency of the battery.

[0005] An object of the present disclosure is to provide an electrode capable of improving the structural efficiency of a battery.

Means for Solving the Problems

[0006] [1] An electrode for a battery, comprising a laminate including an active material layer and a current collector, and a sealing portion covering an end surface of the laminate. The laminate has two opposing main surfaces and end surfaces that are the surfaces of the two main surfaces, The end surface includes the end face and adjacent faces that are portions adjacent to the end face on each of the two main surfaces, The adjacent faces have irregularities, The sealing portion includes a first sealing portion that covers the end face and a second sealing portion that covers at least a part of the adjacent faces, The second sealing portion is present in the recesses of the irregularities of the adjacent faces and does not have a portion higher than the highest height position of the irregularities, An electrode in which the first sealing portion and the second sealing portion are connected.

[0007] [2] A battery including the electrode according to [1].

[0008] [3] The battery according to [2], which is an all-solid-state battery.

[0009] According to the electrode of [1] above, at the end of the laminate including the active material layer and the current collector layer, there is no overhang of the sealing portion in the stacking direction. Therefore, in a stacked battery formed by stacking electrodes including the laminate, an increase in the thickness of the battery due to the presence of the sealing portion between the electrodes is suppressed. Thus, the structural efficiency of the battery of [2] or [3] can be improved by the electrode of [1] above.

[0010] [4] A method for manufacturing the electrode according to claim 1, A step of preparing the laminate including the active material layer and the current collector, A step of applying a liquid containing the material of the sealing portion to the end surface of the laminate, A step of forming the second sealing portion by pressing the laminate in the stacking direction to push the material of the sealing portion into the recesses of the adjacent faces, A manufacturing method including these steps in this order.

[0011] According to the method for manufacturing the electrode of [4] above, the electrode of [1] above without overhang to the sealing portion in the stacking direction can be manufactured at the end of the laminate including the active material layer and the current collector layer in the stacking direction. Thereby, in the stacked battery formed by stacking the electrodes, an increase in the thickness of the battery due to the presence of the sealing portion between the electrodes is suppressed, and the structural efficiency of the battery of [2] or [3] can be improved.

Brief Description of Drawings

[0012]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present disclosure (hereinafter may be abbreviated as "this embodiment"), and examples of the present disclosure (hereinafter may be abbreviated as "this example") will be described. However, this embodiment and this example do not limit the technical scope of the present disclosure.

[0014] When the compound is represented by a stoichiometric composition formula (for example, "LiCoO2" etc.), the stoichiometric composition formula is only a representative example of the compound. The compound may have a non-stoichiometric composition. For example, when lithium cobaltate is represented as "LiCoO2", unless otherwise specified, lithium cobaltate is not limited to the composition ratio of "Li / Co / O = 1 / 1 / 2", and may contain Li, Co, and O at any composition ratio. Furthermore, doping, substitution, etc. with trace elements may also be allowed.

[0015] <Electrode> The electrode for a battery of this embodiment includes a laminate including an active material layer and a current collector, and a sealing portion covering the end surface of the laminate.

[0016] The laminate may be composed of only the active material layers 13a and 13b and the current collector 11, such as the electrode (laminate) 1 shown in Fig. 2(c). Further, the laminate may further include at least one separator layer (solid electrolyte layer) provided in contact with at least one of the active material layer 13a and the active material layer 13b, in addition to the active material layer and the current collector.

[0017] The laminate has two opposing main surfaces (the upper surface and the lower surface in Fig. 2(c)) and the Composed of the side surface of the laminate end face 1a.

[0018] The end surface covered by the sealing portion consists of the end face 1a and the adjacent face 1b which is a portion adjacent to the end face on each of the two main surfaces. The main surfaces usually have minute irregularities, and the adjacent face 1b has minute irregularities.

[0019] The sealing portion consists of a first sealing portion 5a covering the end face and a second sealing portion 5b covering at least a part of the adjacent face.

[0020] The second sealing portion 5b is present in the recess of the irregularities of the adjacent face 1b and does not have a portion higher than the highest height position H of the irregularities.

[0021] The first sealing portion 5a and the second sealing portion 5b are connected. In the cross-sectional schematic view (two-dimensional view) of Fig. 2(c), the first sealing portion 5a and the second sealing portion 5b are depicted as being separated, but in the actual three-dimensional structure, the first sealing portion 5a and the second sealing portion 5b are connected in the recess of the adjacent face 1b.

[0022] In addition, in order to prevent the protrusion of the sealing portion in the stacking direction, it is also conceivable to apply the coating liquid 5 only to the end face 1a of the electrode (stack) 1 so that the coating liquid 5 is not applied to the adjacent face 1b. In this case, an increase in the thickness of the battery due to the protrusion of the sealing portion in the stacking direction is suppressed. However, the adhesiveness of the sealing portion is weak only by the adhesion between the sealing portion and the end face 1a, and there is a possibility that the insulation guarantee is not sufficient. On the other hand, in the electrode of the present embodiment, while suppressing an increase in the thickness of the battery due to the protrusion of the sealing portion in the stacking direction, furthermore, an anchor effect is exhibited by the second sealing portion that is connected to the first sealing portion and is embedded in the recess of the adjacent face 1b of the electrode (stack) 1, so that the sealing portion can be more firmly held at the end of the electrode (stack) 1. Therefore, the electrode of the present embodiment is also excellent in terms of insulation guarantee.

[0023] <Method for manufacturing electrode> As shown in FIG. 1, the method for manufacturing the electrode of the present embodiment includes at least a laminate preparation step (S1), a coating step (S2), and a pressing step (S3) in this order.

[0024] (Laminate preparation step: S1) In the laminate preparation step (S1), a laminate (single-leaf electrode) including an active material layer and a current collector is prepared. Here, various known laminates (single-leaf electrodes) that are components of the laminated battery can be used. As described above, the laminate may further include a separator layer. The prepared laminate may be pressed in the stacking direction (the vertical direction of the paper surface in FIG. 2) in a state where the constituent members are stacked.

[0025] (Coating step: S2) In the coating step (S2), a liquid (coating liquid 5) containing a material for the sealing portion is applied to the end surface of the laminate (see FIG. 2(a)). The material for the sealing portion is a material that can exhibit functions such as short-circuit prevention, and is, for example, an insulating resin material or the like. The liquid (coating liquid 5) is, for example, a slurry containing the material for the sealing portion. As the liquid (coating liquid 5) containing the material for the sealing portion, various known ones used for battery insulation and the like can be used.

[0026] Note that, after the coating step and before the next pressing step, a step of pre-drying the liquid containing the material of the coated sealing portion may be performed. In this case, it is preferable to adjust the degree of dryness so that the material of the sealing portion (semi-cured product containing the material) is maintained in a soft state in the pressing step to such an extent that the material of the sealing portion is pushed into the recesses on the adjacent surfaces of the laminate in the pressing step.

[0027] (Pressing step: S3) In the pressing step (S3), by pressing the laminate in the stacking direction, the material of the sealing portion is pushed into the recesses in the adjacent surface 1b of the laminate, thereby forming the second sealing portion 5b (see FIGS. 2(b) and 2(c)). Note that the pressing step is performed, for example, by mechanical pressure from pressing members 41, 42, etc.

[0028] The pressing step may be performed on a single electrode (sheet electrode), or may be performed collectively on a plurality of electrodes in a stacked state (for example, a laminated battery). Note that when the pressing step is not performed on a single electrode but is performed collectively on a plurality of electrodes in a stacked state (for example, a laminated battery), when stacking a plurality of electrodes (sheet electrodes) with an overhang of the sealing portion remaining in the stacking direction of the sealing portion, there is a possibility that the position of the electrodes may shift due to the overhang of the sealing portion. However, if the pressing step is performed on a single electrode before assembling the battery, such problems can be avoided.

[0029] Further, after the pressing step, a step of fully drying the material of the sealing portion may be performed. The full drying may be performed on a single electrode, or may be performed collectively on a plurality of electrodes in a stacked state (for example, a laminated battery).

[0030] By the above-described steps, the electrode of the present embodiment can be obtained.

[0031] <Battery> The present disclosure also relates to a battery including the above electrodes. The battery is, for example, a laminated battery in which a plurality of electrodes are laminated. The battery may be an all-solid-state battery. In the battery of the present embodiment, the above electrode (the electrode whose end is covered with a sealing portion) may be a negative electrode, a positive electrode, or both a negative electrode and a positive electrode. Hereinafter, an example of the battery (all-solid-state battery) of the present embodiment will be described.

[0032] The all-solid-state battery includes a power storage element. The power storage element includes a positive electrode, a negative electrode, and a separator layer. The positive electrode includes a positive electrode current collector and a positive electrode layer. The negative electrode includes a negative electrode current collector and a negative electrode layer.

[0033] The all-solid-state battery may include, for example, an exterior body that houses the power storage element. The exterior body may be, for example, a pouch made of a metal foil laminate film or the like.

[0034] 《Negative Electrode》 The negative electrode includes a negative electrode current collector and a negative electrode layer. The negative electrode is layered.

[0035] (Negative Electrode Current Collector) The negative electrode current collector may include, for example, a Cu foil, a Ni foil, or the like. The negative electrode current collector may have a thickness of, for example, 5 to 50 μm. For example, a negative electrode layer may be formed by applying a negative electrode composite material to the surface of the negative electrode current collector.

[0036] (Negative Electrode Layer) The negative electrode layer is in close contact with the separator layer. The negative electrode layer may have a thickness of, for example, 10 to 200 μm.

[0037] The negative electrode layer may include negative electrode active material particles and solid electrolyte particles.

[0038] Examples of the components of the negative electrode active material particles include carbon materials such as graphite, Si, SiO x (0 < x < 2), Li4Ti5O 12 and the like.

[0039] The negative electrode active material particles may be secondary particles (aggregates of primary particles). The negative electrode active material particles (secondary particles) may have, for example, a D50 (average particle diameter) of 1 to 50 μm, or may have a D50 of 1 to 20 μm, or may have a D50 of 5 to 15 μm. The primary particles may have, for example, a maximum Feret diameter of 0.1 to 3 μm. Note that "D50" indicates the particle diameter at which the cumulative frequency from the smaller particle diameter side reaches 50% in the volume-based particle size distribution. D50 can be measured by the laser diffraction method.

[0040] The components of the solid electrolyte particles used in the negative electrode layer may be the same as or different from the components of the solid electrolyte particles used in the separator layer described later.

[0041] The components of the solid electrolyte particles are not particularly limited and may be any of sulfide solid electrolytes, oxide solid electrolytes, hydrogen borohydride solid electrolytes, etc.

[0042] The sulfide solid electrolyte may contain S and P. The sulfide solid electrolyte may further contain Li. The sulfide solid electrolyte may further contain, for example, O, Si, etc. The sulfide solid electrolyte may further contain, for example, halogens such as iodine (I), bromine (Br), etc.

[0043] Examples of the sulfide solid electrolyte include LiI-LiBr-Li3PS4, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2O-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, Li3PS4, LiCl-LiBr-Li3PS 4、 LiCl-LiBr-Li2S-P2S5, LiCl-LiBr-Li2S-SiS2, etc. can be used.

[0044] For example, "LiI-LiBr-Li3PS4" represents a sulfide solid electrolyte formed by mixing LiI, LiBr, and Li3PS4 in any molar ratio. For example, the sulfide solid electrolyte may be formed by a mechanochemical method. "Li2S-P2S5" contains Li3PS4. Li3PS4 can be produced, for example, by mixing Li2S and P2S5 at "Li2S / P2S5 = 75 / 25 (molar ratio)".

[0045] Note that the solid electrolyte may be of any type such as the argyrodite type, perovskite type, glass ceramics type, etc.

[0046] The surface of the negative electrode active material particles may be coated with a coating film, for example, to suppress the reaction with solid electrolyte particles and the like.

[0047] The negative electrode layer may further contain, for example, a conductive material. The conductive material can form an electron conduction path within the negative electrode layer. The conductive material can contain any component. The conductive material may contain, for example, at least one selected from the group consisting of carbon black, vapor grown carbon fiber (VGCF), carbon nanotube (CNT), and graphene flakes. The blending amount of the conductive material may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material particles.

[0048] The negative electrode layer may further contain, for example, a binder. The binder can contain any component. The binder may contain, for example, at least one selected from the group consisting of polyvinylidene fluoride (PVdF), vinylidene fluoride - hexafluoropropylene copolymer (PVdF - HFP), styrene butadiene rubber (SBR), and polytetrafluoroethylene (PTFE). The blending amount of the binder may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material particles.

[0049] 《Positive Electrode》 The positive electrode includes a positive electrode current collector and a positive electrode layer. The positive electrode is layered.

[0050] Examples of the positive electrode current collector include Al foil and the like. The positive electrode current collector may have a thickness of, for example, 5 to 50 μm. For example, a positive electrode layer may be formed by coating a positive electrode composite material on the surface of the positive electrode current collector.

[0051] The positive electrode layer is in close contact with the separator layer. The positive electrode layer may have a thickness of, for example, 10 to 200 μm.

[0052] The positive electrode layer may contain positive electrode active material particles and solid electrolyte particles.

[0053] Examples of the components of the positive electrode active material particles include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li(NiCoMn)O2, Li(NiCoAl)O2, LiFePO4, Li2S, P2S 5、 SiS2 and the like. In addition, for example, in "Li(NiCoMn)O2", "(NiCoMn)" indicates that the total of the composition ratios in the parentheses is 1. As long as the total is 1, the individual component amounts are arbitrary. Li(NiCoMn)O2 may contain, for example, Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O2, Li(Ni 0.5 Co 0.2 Mn 0.3 )O2, Li(Ni 0.8 Co 0.1 Mn 0.1 )O2 and the like.

[0054] The positive electrode active material particles may be secondary particles (aggregates of primary particles). The secondary particles of the positive electrode active material particles may have a D50 of, for example, 1 to 50 μm, or may have a D50 of 1 to 20 μm, or may have a D50 of 5 to 15 μm. The primary particles of the positive electrode active material particles may have a maximum Feret diameter of, for example, 0.1 to 3 μm.

[0055] The surface of the positive electrode active material particles may be coated with a coating film for suppressing reaction with solid electrolyte particles and the like.

[0056] The components of the solid electrolyte particles used in the positive electrode layer may be the same as or different from the components of the solid electrolyte particles used in the separator layer described later.

[0057] The positive electrode layer may further contain, for example, a conductive material and a binder. As the conductive material and the binder, for example, the same conductive material and binder as those used in the negative electrode layer can be used.

[0058] The positive electrode active material particles may be subjected to heat treatment (firing). The heat treatment temperature may be, for example, 150 to 300 °C. The heat treatment time may be, for example, 1 to 10 hours. For example, the heat treatment may be carried out in air or in an inert atmosphere.

[0059] 《Separator Layer》 The separator layer is interposed between the positive electrode and the negative electrode. The separator layer contains solid electrolyte particles. The solid electrolyte (solid electrolyte particles) used in the separator layer may be of the same type as or different from at least one of the negative electrode layer and the positive electrode layer.

[0060] The separator layer may further contain a binder. The blending amount of the binder may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the solid electrolyte particles.

[0061] As shown in FIG. 1 of Patent Document 1, when one of the two types of electrodes (negative electrode and positive electrode) is larger in size than the other, an insulating portion (sealing portion) is provided on the end surface (end face and adjacent face) of the larger-sized electrode to prevent short circuit. In the conventional electrode structure, insulation is ensured with an insulating tape or the like. However, when the sizes of the two types of electrodes are different, the material density inside the battery decreases due to the size difference, and the structural efficiency decreases. On the other hand, when the sizes of the two types of electrodes are made the same in order to improve the structural efficiency, if a sealing portion is provided not only on the end faces of the electrodes but also on the adjacent faces to ensure the adhesion of the sealing portion, since there is no step between the two types of electrodes, the protruding sealing portion (the sealing portion on the adjacent face) in the stacking direction will be interposed between the two types of electrodes, thereby causing a problem that the thickness of the stacked battery increases. Therefore, the electrode of the present embodiment has excellent advantages in that, particularly in a stacked battery in which the sizes of the two types of electrodes (negative electrode and positive electrode) are the same, it is possible to suppress an increase in the thickness of the battery and improve the structural efficiency while ensuring the adhesion (insulation) of the sealing portion.

[0062] The embodiments and examples disclosed this time are illustrative in all respects and not restrictive. The technical scope determined by the description of the claims includes all modifications within the meaning equivalent to the claims.

Explanation of Reference Numerals

[0063] 1 Electrode (stack), 1a End face, 1b Adjacent face, 11 Current collector, 13a, 13b Active material layer, 41, 42 Pressing member, 5 Coating liquid, 5a First sealing portion, 5b Second sealing portion.

Claims

1. An electrode for a battery, comprising a laminate including an active material layer, a current collector, and a separator layer that is a solid electrolyte layer, and a sealing portion that covers an end surface of the laminate. The laminate has two opposing main surfaces and an end surface formed by a side surface of the laminate. The end surface includes the end face and adjacent faces that are portions adjacent to the end face on each of the two main surfaces. The adjacent faces have irregularities. The sealing portion includes a first sealing portion that covers the end face and a second sealing portion that covers at least a part of the adjacent faces. The second sealing portion exists only in the recesses of the irregularities of the adjacent faces and does not have a portion higher than the highest height position of the irregularities. The second sealing portion is not filled up to the inside of the active material layer other than in the recesses of the irregularities of the adjacent faces. The first sealing portion and the second sealing portion are connected. An electrode in which an end portion of the laminate and the first sealing portion are joined by an anchor effect of the second sealing portion filled in the recesses of the adjacent faces.

2. A battery including the electrode according to claim 1.

3. The battery according to claim 2, which is an all-solid-state battery.

4. A method for manufacturing the electrode according to claim 1, including: a step of preparing the laminate including the active material layer, the current collector, and the separator layer; a step of applying a liquid containing a material of the sealing portion to the end surface of the laminate; a step of forming the second sealing portion by pressing the laminate in the lamination direction to push the material of the sealing portion into the recesses of the adjacent faces; The manufacturing method including these steps in this order.

Images