Secondary battery electrode structure, secondary battery and vehicle

Abstract

Suppresses uneven reactions between electrodes in secondary batteries. [Solution] An electrode structure (6) for a secondary battery includes a positive electrode foil (10), a positive electrode active material layer (20) supported on the positive electrode foil (10), a negative electrode foil (40), a negative electrode active material layer (50) supported on the negative electrode foil (40), and a separator (70) interposed between the positive electrode active material layer (20) and the negative electrode active material layer (50). The positive electrode active material layer (20) has positive electrode-side passages (80) extending from the positive electrode foil (10) side to the separator (70) side. The positive electrode-side passages (80) have a higher ionic conductivity (κ) than a positive electrode-side main body portion (23) of the positive electrode active material layer (20) other than the positive electrode-side passages (80).

Description

[Technical Field]

[0001] The present disclosure relates to an electrode structure for a secondary battery, a secondary battery, and a vehicle. [Background technology]

[0002] The secondary battery disclosed in Patent Document 1 includes electrodes (positive and negative electrodes), a separator, and an electrolyte. The positive and negative electrodes are separated by the separator to prevent them from contacting each other.

[0003] When charging a secondary battery, the positive and negative electrodes are connected by a charging circuit including an external power source, and ions (e.g., lithium ions) on the positive electrode side move to the negative electrode side through the electrolyte, creating a potential difference between the two electrodes and charging. When discharging a secondary battery, the positive and negative electrodes are connected by a discharge circuit, and ions stored on the negative electrode side move to the positive electrode side, releasing electrical energy and discharging.

[0004] In Patent Document 1, the electrode includes an electrode foil and an electrode active material layer. The electrode active material layer is a laminate of two or more active material monolayers. A barrier layer is formed between the active material monolayers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2018-507528 Summary of the Invention [Problem to be solved by the invention]

[0006] In the secondary battery according to Patent Document 1, a barrier layer is formed in the electrode active material layer, which reduces the conductivity in the inter-electrode direction (the direction between the positive and negative electrodes), causing uneven reactions and deteriorating cycle characteristics.

[0007] An object of the present disclosure is to suppress uneven reactions between electrodes in a secondary battery. [Means for solving the problem]

[0008] The electrode structure for a secondary battery according to the present disclosure comprises a first electrode foil, a first electrode active material layer supported on the first electrode foil, a second electrode foil, a second electrode active material layer supported on the second electrode foil, and a separator interposed between the first electrode active material layer and the second electrode active material layer, wherein the first electrode active material layer has a first passage extending from the first electrode foil side to the separator side, and the first passage has a higher ionic conductivity than a portion of the first electrode active material layer other than the first passage.

[0009] By providing the first passages with high ion conductivity in the first electrode active material layer, the flow of ions between the first electrode foil side and the separator side in the first electrode active material layer is promoted, and unevenness in the concentration of ions between the first electrode foil side and the separator side in the first electrode active material layer is suppressed.

[0010] This suppresses unevenness in ion concentration in the inter-electrode direction in the secondary battery, thereby suppressing uneven ion reactions in the secondary battery and improving cycle characteristics.

[0011] As described above, it is possible to suppress uneven reactions between electrodes in a secondary battery and improve cycle characteristics.

[0012] In one embodiment, the first passages have a higher porosity than the portion of the first electrode active material layer other than the first passages.

[0013] It is easy to create a first passage with high ionic conductivity.

[0014] In one embodiment, the first passage comprises a through hole.

[0015] By making the porosity of the first passage 100%, it is possible to create a first passage with extremely high ionic conductivity.

[0016] In one embodiment, the first passageway is constructed from the same material as the separator.

[0017] It is easy to create a first passage with high ionic conductivity.

[0018] In one embodiment, the first passages are made of a material having a lower electrical resistivity than the portion of the first electrode active material layer other than the first passages.

[0019] It is easy to create a first passage with high ionic conductivity.

[0020] In one embodiment, the electrode structure for a secondary battery includes a first electrode tab connected to the first electrode foil, and the first passage is disposed in a portion corresponding to the first electrode tab.

[0021] In the portion of the first electrode active material layer corresponding to the first electrode tab, uneven ion concentration is likely to occur between the first electrode foil side and the separator side of the first electrode active material layer. The first passage is preferentially provided in the portion where uneven ion concentration is likely to occur. This is advantageous in suppressing uneven ion concentration between the first electrode foil side and the separator side of the first electrode active material layer.

[0022] In one embodiment, the first passages arranged in the portion corresponding to the first electrode tab have higher ionic conductivity than the first passages arranged in the portion other than the portion corresponding to the first electrode tab.

[0023] The ionic conductivity of the first passages arranged in the portion where the ion concentration tends to be uneven (corresponding to the first electrode tab in the first electrode active material layer) is increased, which is advantageous in suppressing unevenness in the ion concentration between the first electrode foil side and the separator side in the first electrode active material layer.

[0024] In one embodiment, the first passage arranged in the portion corresponding to the first electrode tab has a larger passage area than the first passage arranged in the portion other than the portion corresponding to the first electrode tab.

[0025] The ionic conductivity of the first passage arranged in the portion where the ion concentration tends to be uneven (corresponding to the first electrode tab in the first electrode active material layer) can be easily increased by increasing the passage area.

[0026] In one embodiment, the second electrode active material layer has a second passage extending from the second electrode foil side to the separator side, and the second passage has a higher ionic conductivity than the portion of the second electrode active material layer other than the second passage.

[0027] By providing the second passages with high ion conductivity in the second electrode active material layer, the flow of ions between the second electrode foil side and the separator side in the second electrode active material layer is promoted, and unevenness in the concentration of ions between the second electrode foil side and the separator side in the second electrode active material layer is suppressed.

[0028] A secondary battery according to the present disclosure includes the electrode structure for a secondary battery, an electrolyte, and a case that accommodates the electrode structure for a secondary battery and the electrolyte.

[0029] A vehicle according to the present disclosure includes the secondary battery, an electric motor driven by the secondary battery, and wheels driven by the electric motor. [Effects of the Invention]

[0030] According to the present disclosure, it is possible to suppress uneven reactions between electrodes in a secondary battery and improve cycle characteristics. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 shows a vehicle according to the first embodiment. [Figure 2] FIG. 2 is a perspective view showing the secondary battery according to the first embodiment. [Figure 3] FIG. 3 is a perspective view showing the secondary battery according to the first embodiment during charging. [Figure 4] FIG. 4 is a perspective view showing the secondary battery according to the first embodiment during discharging. [Figure 5] FIG. 5 is a cross-sectional view of the secondary battery according to the first embodiment taken along line V in FIG. [Figure 6] FIG. 6 is a view corresponding to FIG. 5 according to the second embodiment. [Figure 7] FIG. 7 is a view corresponding to FIG. 5 according to the third embodiment. [Figure 8] FIG. 8 is a view corresponding to FIG. 5 according to the fourth embodiment. [Figure 9] FIG. 9 is a view corresponding to FIG. 2 according to the fifth embodiment. [Figure 10] FIG. 10 shows simulation data of the distribution of the concentration of lithium ions according to the first example. [Figure 11] FIG. 11 shows simulation data of the distribution of the concentration of lithium ions according to the second example. [Figure 12] FIG. 12 shows simulation data of the distribution of lithium ion concentration according to the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0033] First Embodiment A secondary battery electrode structure 6, a secondary battery 5, and a vehicle 1 according to a first embodiment will be described.

[0034] (vehicle) 1 shows a vehicle 1 according to a first embodiment. The vehicle 1 is an electric vehicle or a hybrid vehicle. The vehicle 1 includes a battery unit 2, an electric motor 3, and wheels 4.

[0035] The battery unit 2 includes a plurality of secondary batteries 5. In other words, the vehicle 1 is equipped with a plurality of secondary batteries 5. The battery unit 2 is disposed below a floor panel of the vehicle 1. The secondary batteries 5 will be described in detail later.

[0036] The electric motor 3 is disposed in a motor room at the front of the vehicle 1. An engine may be disposed in the motor room together with the electric motor 3. The electric motor 3 is driven by power supplied from the secondary battery 5 of the battery unit 2. In detail, a power control device such as an inverter or a converter is interposed between the battery unit 2 and the electric motor 3.

[0037] The wheels 4 include left and right front wheels and left and right rear wheels. The wheels 4 are driven by the electric motor 3. The wheels 4 rotate when the rotation of the electric motor 3 is transmitted to them. A reducer, a propeller shaft, or the like may be interposed between the electric motor 3 and the wheels 4.

[0038] In vehicles 1 such as electric vehicles and hybrid vehicles, high-rate (rapid) charging and discharging of the secondary battery 5 is often performed. As will be described in detail later, high-rate charging and discharging of the secondary battery 5 causes a bias in ionic conductivity between the electrodes, which ultimately causes uneven reactions between the electrodes and is likely to deteriorate the cycle characteristics.

[0039] (Secondary battery) FIG. 2 is a perspective view of a secondary battery 5. Front, rear, left, right, top, and bottom are indicated in FIG. 2. The secondary battery 5 includes a secondary battery electrode structure 6, an electrolyte 7, and a case 8. The secondary battery 5 is a lithium-ion secondary battery.

[0040] (Electrode structure for secondary batteries) The electrode structure 6 for a secondary battery includes a positive electrode foil 10 as a first electrode foil, a positive electrode active material layer 20 as a first electrode active material layer, a positive electrode tab 30 as a first electrode tab, a negative electrode foil 40 as a second electrode foil, a negative electrode active material layer 50 as a second electrode active material layer, a negative electrode tab 60 as a second electrode tab, and a separator 70.

[0041] The positive electrode foil 10 is made of a thin metal film. The positive electrode foil 10 is made of, for example, aluminum foil. The positive electrode foil 10 is in the form of a sheet that has a thickness in the up-down direction and extends in the front-back and left-right directions. The positive electrode foil 10 is disposed below the electrode structure 6 for a secondary battery.

[0042] The positive electrode active material layer 20 is supported on the upper surface of the positive electrode foil 10. The positive electrode active material layer 20 is in the form of a sheet that has a thickness in the up-down direction and extends in the front-rear and left-right directions.

[0043] The positive electrode active material layer 20 is formed by mixing a positive electrode active material with additives (binder and conductive additive) and applying the mixture to the positive electrode foil 10. The positive electrode active material is preferably a composite metal oxide containing one or more elements selected from the group consisting of cobalt, manganese, and nickel and lithium, a phosphate-based lithium compound, or a silicate-based lithium compound.

[0044] Although details will be described later, the positive electrode active material layer 20 has positive electrode-side passages 80 as first passages.

[0045] The positive electrode tab 30 is connected to the positive electrode foil 10. The positive electrode tab 30 may be integral with or separate from the positive electrode foil 10. The positive electrode tab 30 is made of, for example, aluminum.

[0046] The positive electrode tab 30 extends in the front-rear direction. The rear end of the positive electrode tab 30 is connected to the right end of the front edge of the positive electrode foil 10. The front end of the positive electrode tab 30 is connected to a positive electrode terminal fixed to a sealing plate (not shown) of the case 8 via a positive electrode current collector (not shown) or the like.

[0047] Hereinafter, the positive electrode foil 10, the positive electrode active material layer 20, the positive electrode tab 30, the positive electrode side current collector, and the positive electrode terminal will be collectively referred to as a positive electrode A as a first electrode.

[0048] The negative electrode foil 40 is made of a thin metal film. The negative electrode foil 40 is made of, for example, copper foil. The negative electrode foil 40 is in the form of a sheet that has a thickness in the up-down direction and extends in the front-rear and left-right directions. The negative electrode foil 40 is disposed on top of the secondary battery electrode structure 6.

[0049] The negative electrode active material layer 50 is supported on the lower surface of the negative electrode foil 40. The negative electrode active material layer 50 is in the form of a sheet that has a thickness in the up-down direction and extends in the front-rear and left-right directions.

[0050] The negative electrode active material layer 50 is formed by mixing a negative electrode active material with additives (binder, thickener, and conductive additive) and applying the mixture to the negative electrode foil 40. The negative electrode active material is not particularly limited and may be, for example, a graphite-based carbon material, a lithium transition metal composite oxide such as lithium titanate, a lithium transition metal composite nitride, or a silicon compound containing Si element. Note that graphite-based carbon material is a general term for a carbon material consisting only of graphite and a carbon material in which graphite accounts for 50% by mass or more.

[0051] Although details will be described later, the negative electrode active material layer 50 has negative electrode-side passages 90 as second passages.

[0052] The negative electrode tab 60 is connected to the negative electrode foil 40. The negative electrode tab 60 may be integral with or separate from the negative electrode foil 40. The negative electrode tab 60 is made of, for example, copper.

[0053] The negative electrode tab 60 extends in the front-rear direction. The rear end of the negative electrode tab 60 is connected to the left end of the front edge of the negative electrode foil 40. The front end of the negative electrode tab 60 is connected to a negative electrode terminal fixed to a sealing plate (not shown) of the case 8 via a negative electrode current collector (not shown) or the like.

[0054] Hereinafter, the negative electrode foil 40, the negative electrode active material layer 50, the negative electrode tab 60, the negative electrode-side current collector, and the negative electrode terminal will be collectively referred to as a negative electrode B as a second electrode.

[0055] The separator 70 is interposed between the positive electrode active material layer 20 and the negative electrode active material layer 50. The separator 70 is disposed above the positive electrode active material layer 20 and below the negative electrode active material layer 50. The separator 70 is in the form of a sheet that has a thickness in the up-down direction and extends in the front-rear and left-right directions.

[0056] The separator 70 is formed of a thin film of an insulating material. The separator 70 is porous. The separator 70 is mainly made of a synthetic resin, such as polyethylene or polypropylene. The separator 70 may also contain ceramic.

[0057] (Electrolyte and case) The electrolytic solution 7 is formed by dissolving an electrolyte in a non-aqueous solvent. For example, a carbonate ester solvent is used as the non-aqueous solvent. For example, cyclic carbonate, ethylene carbonate, propylene carbonate, etc. is used as the non-aqueous solvent. For example, a lithium salt is used as the electrolyte. For example, the lithium salt includes LiPF6, LiClO4, and LiBF4.

[0058] The case 8 accommodates the secondary battery electrode structure 6 (positive electrode foil 10, positive electrode active material layer 20, positive electrode tab 30, negative electrode foil 40, negative electrode active material layer 50, negative electrode tab 60, and separator 70) and the electrolyte 7. In the case 8, the secondary battery electrode structure 6 is immersed in the electrolyte 7.

[0059] The case 8 has an opening (not shown). The electrolyte 7 is introduced into the case 8 through the opening. The opening of the case 8 is covered with a sealing plate (not shown). A positive electrode terminal (not shown) and a negative electrode terminal (not shown) are fixed to the sealing plate. The positive electrode terminal is connected to a positive electrode tab 30 via a positive electrode side current collector (not shown) or the like. The negative electrode terminal is connected to a negative electrode tab 60 via a negative electrode side current collector (not shown) or the like. The positive electrode terminal and the negative electrode terminal are connected to external circuits (a discharge circuit and a charge circuit).

[0060] (Positive electrode passage and negative electrode passage) As described above, the positive electrode active material layer 20 has the positive electrode-side passages 80 as first passages. The positive electrode-side passages 80 extend from the positive electrode foil 10 side to the separator 70 side in the positive electrode active material layer 20. In other words, the positive electrode-side passages 80 extend from the lower end of the positive electrode active material layer 20 to the upper end of the positive electrode active material layer 20.

[0061] There are multiple (four in this example) positive electrode-side passages 80. The multiple positive electrode-side passages 80 are aligned at intervals in the left-right direction. The positive electrode-side passages 80 extend in a groove shape from the front end of the positive electrode active material layer 20 to the rear end of the positive electrode active material layer 20.

[0062] The first positive electrode side passage 80 from the right is disposed in a portion 21 (hereinafter referred to as the "positive electrode side tab corresponding portion 21") corresponding to the positive electrode tab 30. In detail, the first positive electrode side passage 80 from the right is disposed in the positive electrode side tab corresponding portion 21 that overlaps with the positive electrode tab 30 in the left-right direction (in which the positive electrode side passages 80 are aligned).

[0063] The second to fourth positive electrode side passages 80 from the right are arranged in portions 22 (hereinafter referred to as "positive electrode side tab non-corresponding portions 22") other than the positive electrode side tab corresponding portions 21. In detail, the second to fourth positive electrode side passages 80 from the right are arranged in positive electrode side tab non-corresponding portions 22 that do not overlap with the positive electrode tab 30 in the left-right direction (where the positive electrode side passages 80 are lined up).

[0064] As described above, the negative electrode active material layer 50 has the negative electrode-side passages 90 as second passages. The negative electrode-side passages 90 extend from the negative electrode foil 40 side to the separator 70 side in the negative electrode active material layer 50. In other words, the negative electrode-side passages 90 extend from the upper end of the negative electrode active material layer 50 to the lower end of the negative electrode active material layer 50.

[0065] There are multiple negative electrode-side passages 90. The multiple negative electrode-side passages 90 are aligned at intervals in the left-right direction. The negative electrode-side passages 90 extend in a groove shape from the front end of the negative electrode active material layer 50 to the rear end of the negative electrode active material layer 50.

[0066] The first negative electrode-side passage 90 from the left is disposed in a portion 51 (hereinafter referred to as the "negative electrode-side tab corresponding portion 51") corresponding to the negative electrode tab 60. In detail, the first negative electrode-side passage 90 from the left is disposed in the negative electrode-side tab corresponding portion 51 that overlaps with the negative electrode tab 60 in the left-right direction (in which the negative electrode-side passages 90 are aligned).

[0067] The second to fourth negative electrode-side passages 90 from the left are arranged in a portion 52 (hereinafter referred to as the "negative electrode-side tab non-corresponding portion 52") other than the negative electrode-side tab corresponding portion 51. In detail, the second to fourth negative electrode-side passages 90 from the left are arranged in the negative electrode-side tab non-corresponding portion 52 that does not overlap with the negative electrode tab 60 in the left-right direction (where the negative electrode-side passages 90 are aligned).

[0068] (Charging and discharging secondary batteries) Fig. 3 is a perspective view of the secondary battery 5 during charging. Fig. 4 is a perspective view of the secondary battery 5 during discharging. For simplicity, the electrolyte 7 and the case 8 are not shown.

[0069] 3, when charging the secondary battery 5, the positive electrode A and negative electrode B (more precisely, the positive electrode terminal and negative electrode terminal) are connected to a charging circuit 101. The charging circuit 101 is provided with an external power supply 101a.

[0070] During charging, negatively charged electrons e- are taken into the negative electrode B through the charging circuit 101. This causes the negative electrode B to become negatively charged, so to eliminate this, positively charged lithium ions Li+ move from the positive electrode A to the negative electrode B. A potential difference is created between the positive electrode A and the negative electrode B, and charging occurs. During charging, the lithium ions Li+ move from the positive electrode active material layer 20 to the negative electrode active material layer 50 through the separator 70.

[0071] 4, when discharging the secondary battery 5, the positive electrode A and negative electrode B (more precisely, the positive electrode terminal and negative electrode terminal) are connected to a discharge circuit 102. The discharge circuit 102 is provided with a resistor 102a.

[0072] Immediately before discharge, negatively charged electrons e- have been stored in the negative electrode B due to charging. During discharge, the negatively charged electrons e- are extracted from the negative electrode B through the discharge circuit 102. Electric power is generated and discharge occurs. As the electrons e- are extracted from the negative electrode B, positively charged lithium ions Li+ move from the negative electrode B to the positive electrode A. During discharge, the lithium ions Li+ move from the negative electrode active material layer 50 through the separator 70 to the positive electrode active material layer 20.

[0073] (ionic conductivity) Fig. 5 shows a cross-sectional view of the secondary battery 5 taken along line V in Fig. 2. For ease of understanding, the space E is illustrated larger than it actually is.

[0074] The positive electrode-side passages 80 have a higher ionic conductivity κ than the portion 23 other than the positive electrode-side passages 80 (hereinafter referred to as the "positive electrode-side main body portion 23") of the positive electrode active material layer 20. The ionic conductivity κ1a of the positive electrode-side passages 80 is higher than the ionic conductivity κ1b of the positive electrode-side main body portion 23.

[0075] The negative electrode-side passages 90 have a higher ionic conductivity κ than the portion 53 other than the negative electrode-side passages 90 (hereinafter referred to as the "negative electrode-side main body portion 53") of the negative electrode active material layer 50. The ionic conductivity κ2a of the negative electrode-side passages 90 is higher than the ionic conductivity κ2b of the negative electrode-side main body portion 53.

[0076] The unit used for ionic conductivity κ is, for example, [S / m] (Siemens per meter). Ionic conductivity κ [S / m] is the reciprocal of electrical resistivity ρ [Ω·m] (κ=1 / ρ). Note that S is the reciprocal of Ω (S=1 / Ω). Ionic conductivity κ indicates the ease with which ions pass through.

[0077] The positive electrode side passages 80 have a higher porosity ε than the positive electrode side main body portion 23 other than the positive electrode side passages 80 in the positive electrode active material layer 20. The negative electrode side passages 90 have a higher porosity ε than the negative electrode side main body portion 53 other than the negative electrode side passages 90 in the negative electrode active material layer 50.

[0078] The porosity ε is the ratio of the volume of space E to the total volume of any part of a substance. The porosity ε ranges from 0% to 100%.

[0079] The porosity ε1a of the positive electrode side passage 80 is the ratio of the volume of the space E to the entire volume of the positive electrode side passage 80. The porosity ε1b of the positive electrode side main body portion 23 is the ratio of the volume of the space E to the entire volume of the positive electrode side main body portion 23. The porosity ε1a of the positive electrode side passage 80 is higher than the porosity ε1b of the positive electrode side main body portion 23 (ε1a>ε1b).

[0080] The porosity ε2a of the negative electrode side passage 90 is the ratio of the volume of the space E to the entire volume of the negative electrode side passage 90. The porosity ε2b of the negative electrode side main body portion 53 is the ratio of the volume of the space E to the entire volume of the negative electrode side main body portion 53. The porosity ε2a of the negative electrode side passage 90 is higher than the porosity ε2b of the negative electrode side main body portion 53 (ε2a > ε2b).

[0081] The porosity ε3 of the separator 70 is the ratio of the volume of the space E to the volume of the separator 70. The separator 70 is porous, and therefore has a high porosity ε3. For example, the porosity ε3 of the separator 70 is higher than the porosity ε1b of the positive electrode side main body portion 23 and the porosity ε2b of the negative electrode side main body portion 53 (ε3>ε1b, ε3>ε2b).

[0082] The chemical composition of the material constituting the positive electrode side passage 80 may be the same as or different from the chemical composition of the material constituting the positive electrode side main body portion 23. The chemical composition of the material constituting the negative electrode side passage 90 may be the same as or different from the chemical composition of the material constituting the negative electrode side passage 90.

[0083] (Action and effect) The provision of the positive electrode-side passages 80 with high ionic conductivity κ in the positive electrode active material layer 20 promotes the flow of lithium ions Li+ between the positive electrode foil 10 side and the separator 70 side in the positive electrode active material layer 20. The bias in the concentration of lithium ions Li+ between the positive electrode foil 10 side and the separator 70 side in the positive electrode active material layer 20 is suppressed.

[0084] Similarly, by providing the anode-side passages 90 with high ionic conductivity κ in the anode active material layer 50, the flow of lithium ions Li+ is promoted between the anode foil 40 side and the separator 70 side in the anode active material layer 50. The bias in the concentration of lithium ions Li+ between the anode foil 40 side and the separator 70 side in the anode active material layer 50 is suppressed.

[0085] This suppresses unevenness in the concentration of lithium ions Li+ in the inter-electrode direction (direction between the positive electrode A and the negative electrode B) in the secondary battery 5. In the secondary battery 5, uneven reaction of lithium ions Li+ between the electrodes (between the positive electrode A and the negative electrode B) is suppressed.

[0086] As described above, it is possible to suppress uneven reactions between the electrodes in the secondary battery 5 and improve the cycle characteristics.

[0087] By increasing the porosity ε of the positive electrode-side passages 80, it is possible to easily produce positive electrode-side passages 80 with a high ionic conductivity κ. Similarly, by increasing the porosity ε of the negative electrode-side passages 90, it is possible to easily produce negative electrode-side passages 90 with a high ionic conductivity κ.

[0088] In the positive electrode side tab corresponding portion 21 of the positive electrode active material layer 20 (particularly the rear end portion 21a of the positive electrode side tab corresponding portion 21 opposite the positive electrode tab 30), a bias in the concentration of lithium ions Li+ is likely to occur between the positive electrode foil 10 side and the separator 70 side of the positive electrode active material layer 20. The positive electrode side passages 80 are preferentially provided in the positive electrode side tab corresponding portion 21 where the concentration of lithium ions Li+ is likely to be biased. This is advantageous in suppressing a bias in the concentration of lithium ions Li+ between the positive electrode foil 10 side and the separator 70 side of the positive electrode active material layer 20.

[0089] Similarly, in the negative electrode side tab corresponding portion 51 of the negative electrode active material layer 50 (particularly the rear end portion 51a of the negative electrode side tab corresponding portion 51 opposite the negative electrode tab 60), a bias in the concentration of lithium ions Li+ is likely to occur between the negative electrode foil 40 side and the separator 70 side of the negative electrode active material layer 50. The negative electrode side passages 90 are preferentially provided in the negative electrode side tab corresponding portion 51 where the concentration of lithium ions Li+ is likely to become biased. This is advantageous in suppressing a bias in the concentration of lithium ions Li+ between the negative electrode foil 40 side and the separator 70 side of the negative electrode active material layer 50.

[0090] The secondary battery 5 including the electrode structure for secondary battery 6 according to this embodiment is particularly effective when high-rate charging and discharging is performed, and is particularly suitable for use in the vehicle 1.

[0091] Second Embodiment A second embodiment will be described. In the following description, the same components as those in the above embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted. Fig. 6 is a view equivalent to Fig. 5.

[0092] The positive electrode-side passages 80 are constituted by positive electrode-side through holes 81 serving as through holes. The positive electrode-side through holes 81 extend from the positive electrode foil 10 side to the separator 70 side in the positive electrode active material layer 20. The negative electrode-side passages 90 are constituted by negative electrode-side through holes 91 serving as through holes. The negative electrode-side through holes 91 extend from the negative electrode foil 40 side to the separator 70 side in the negative electrode active material layer 50.

[0093] The porosity ε1a of the positive electrode side through-hole 81 (positive electrode side passage 80) is 100% (ε1a=100%). The porosity ε2a of the negative electrode side through-hole 91 (negative electrode side passage 90) is 100% (ε2a=100%).

[0094] The other configurations are the same as those in the first embodiment.

[0095] By configuring the positive electrode side passage 80 with the positive electrode side through-hole 81 (making the porosity ε 100%), it is possible to create a positive electrode side passage 80 with an extremely high ionic conductivity κ. Similarly, by configuring the negative electrode side passage 90 with the negative electrode side through-hole 91 (making the porosity ε 100%), it is possible to create a negative electrode side passage 90 with an extremely high ionic conductivity κ.

[0096] Third Embodiment A third embodiment will be described. In the following description, the same components as those in the above embodiments are given the same reference numerals, and detailed description thereof will be omitted. Fig. 7 is a view equivalent to Fig. 5.

[0097] The positive electrode passage 80 is made of the same material as the separator 70. The negative electrode passage 90 is made of the same material as the separator 70.

[0098] The positive electrode passage 80 and the negative electrode passage 90 are formed of an insulating material. The positive electrode passage 80 and the negative electrode passage 90 are porous. The positive electrode passage 80 and the negative electrode passage 90 are mainly made of a synthetic resin such as polyethylene or polypropylene. The positive electrode passage 80 and the negative electrode passage 90 may contain ceramic.

[0099] The porosity ε1a of the positive electrode side passages 80 is almost the same as the porosity ε3 of the separator 70 (ε1a≈ε3), and is higher than the porosity ε1b of the positive electrode side main body portion 23 (ε1a>ε1b).

[0100] The porosity ε2a of the negative electrode side passages 90 is almost the same as the porosity ε3 of the separator 70 (ε2a≈ε3), and is higher than the porosity ε2b of the negative electrode side main body portion 53 (ε2a>ε2b).

[0101] The other configurations are the same as those of the first and second embodiments.

[0102] By constructing the positive electrode side passages 80 from the same material as the separator 70, it is possible to easily produce positive electrode side passages 80 with a high ionic conductivity κ. Similarly, by constructing the negative electrode side passages 90 from the same material as the separator 70, it is possible to easily produce negative electrode side passages 90 with a high ionic conductivity κ.

[0103] <Fourth embodiment> A fourth embodiment will be described. In the following description, the same components as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. Fig. 8 is a view corresponding to Fig. 5 according to the fourth embodiment.

[0104] The positive electrode side passages 80 are made of a material having a lower electrical resistivity ρ than the positive electrode side main body portion 23 other than the positive electrode side passages 80 in the positive electrode active material layer 20. The negative electrode side passages 90 are made of a material having a lower electrical resistivity ρ than the negative electrode side main body portion 53 other than the negative electrode side passages 90 in the negative electrode active material layer 50.

[0105] The material forming the positive electrode passage 80 is, for example, a carbon material such as a conductive additive. The material forming the negative electrode passage 90 is, for example, a carbon material such as a conductive additive.

[0106] The electrical resistivity ρ1a of the material constituting the positive electrode side passage 80 is lower than the electrical resistivity ρ1b of the material constituting the positive electrode side main body portion 23 (ρ1a<ρ1b). The electrical resistivity ρ2a of the material constituting the negative electrode side passage 90 is lower than the electrical resistivity ρ2b of the material constituting the negative electrode side main body portion 53 (ρ2a<ρ2b).

[0107] The porosity of the material forming the positive electrode side passage 80 may be the same as the porosity of the material forming the positive electrode side main body portion 23. The porosity of the material forming the negative electrode side passage 90 may be the same as the porosity of the material forming the negative electrode side main body portion 53.

[0108] The other configurations are the same as those of the first to third embodiments.

[0109] By constructing the positive electrode side passage 80 from a material with a low electrical resistivity ρ, it is possible to easily create a positive electrode side passage 80 with high electrical conductivity. Similarly, by constructing the negative electrode side passage 90 from a material with a low electrical resistivity ρ, it is possible to easily create a negative electrode side passage 90 with high electrical conductivity.

[0110] Fifth Embodiment A fifth embodiment will be described. In the following description, the same components as those in the above embodiments are given the same reference numerals, and detailed description thereof will be omitted. Fig. 9 is a view equivalent to Fig. 2.

[0111] There are multiple (13 in this example) positive electrode side passages 80. The first to third positive electrode side passages 80 from the right are arranged in the positive electrode side tab corresponding portion 21. In detail, the first to third positive electrode side passages 80 from the right are arranged in the positive electrode side tab corresponding portion 21 that overlaps the positive electrode tab 30 in the left-right direction (in which the positive electrode side passages 80 are lined up).

[0112] The fourth to thirteenth positive electrode side passages 80 from the right are arranged in the positive electrode side tab non-corresponding portions 22. In detail, the fourth to thirteenth positive electrode side passages 80 from the right are arranged in the positive electrode side tab non-corresponding portions 22 that do not overlap with the positive electrode tabs 30 in the left-right direction (where the positive electrode side passages 80 are lined up).

[0113] The positive electrode side passages 80 (first to third from the right) arranged in the positive electrode side tab corresponding portion 21 have a higher ionic conductivity κ than the positive electrode side passages 80 (fourth to thirteenth from the right) arranged in the positive electrode side tab non-corresponding portion 22.

[0114] The ionic conductivity κ1ax of the positive electrode passages 80 arranged in the positive electrode tab corresponding portion 21 is higher than the ionic conductivity κ1ay of the positive electrode passages 80 arranged in the positive electrode tab non-corresponding portion 22.

[0115] The positive electrode side passages 80 (first to third from the right) arranged in the positive electrode side tab corresponding portion 21 have a larger passage area F than the positive electrode side passages 80 (fourth to thirteenth from the right) arranged in the positive electrode side tab non-corresponding portion 22.

[0116] The passage area F1ax of the positive electrode side passage 80 arranged in the positive electrode side tab corresponding portion 21 is larger than the passage area F1ay of the positive electrode side passage 80 arranged in the positive electrode side tab non-corresponding portion 22.

[0117] The positive electrode side passages 80 (first to third from the right) arranged in the positive electrode side tab corresponding portion 21 have a larger passage width H in the left-right direction (where the positive electrode side passages 80 are lined up) than the positive electrode side passages 80 (fourth to thirteenth from the right) arranged in the positive electrode side tab non-corresponding portion 22.

[0118] The passage width H1ax of the positive electrode side passage 80 arranged in the positive electrode side tab corresponding portion 21 is larger than the passage width H1ay of the positive electrode side passage 80 arranged in the positive electrode side tab non-corresponding portion 22.

[0119] There are multiple (13 in this example) negative electrode passages 90. The first to third negative electrode passages 90 from the left are arranged in the negative electrode tab corresponding portions 51. In detail, the first to third negative electrode passages 90 from the left are arranged in the negative electrode tab corresponding portions 51 that overlap the negative electrode tab 60 in the left-right direction (in which the negative electrode passages 90 are arranged).

[0120] The fourth to thirteenth negative electrode passages 90 from the left are arranged in the negative electrode tab non-corresponding portions 52. In detail, the fourth to thirteenth negative electrode passages 90 from the left are arranged in the negative electrode tab non-corresponding portions 52 that do not overlap with the negative electrode tab 60 in the left-right direction (where the negative electrode passages 90 are lined up).

[0121] The negative electrode side passages 90 (first to third from the left) arranged in the negative electrode side tab corresponding portion 51 have a higher ionic conductivity κ than the negative electrode side passages 90 (fourth to thirteenth from the left) arranged in the negative electrode side tab non-corresponding portion 52.

[0122] The ionic conductivity κ2ax of the negative electrode passages 90 arranged in the negative electrode tab corresponding portion 51 is higher than the ionic conductivity κ2ay of the negative electrode passages 90 arranged in the negative electrode tab non-corresponding portion 52.

[0123] The negative electrode side passages 90 (first to third from the left) arranged in the negative electrode side tab corresponding portion 51 have a larger passage area F than the negative electrode side passages 90 (fourth to thirteenth from the left) arranged in the negative electrode side tab non-corresponding portion 52.

[0124] The passage area F2ax of the negative electrode side passage 90 arranged in the negative electrode side tab corresponding portion 51 is larger than the passage area F2ay of the negative electrode side passage 90 arranged in the negative electrode side tab non-corresponding portion 52.

[0125] The negative electrode side passages 90 (first to third from the left) arranged in the negative electrode side tab corresponding portion 51 have a larger passage width H in the left-right direction (where the negative electrode side passages 90 are lined up) than the negative electrode side passages 90 (fourth to thirteenth from the left) arranged in the negative electrode side tab non-corresponding portion 52.

[0126] The passage width H2ax of the negative electrode side passage 90 arranged in the negative electrode side tab corresponding portion 51 is larger than the passage width H2ay of the negative electrode side passage 90 arranged in the negative electrode side tab non-corresponding portion 52.

[0127] The passage area F is obtained by multiplying the passage width H in the left-right direction by the depth in the front-rear direction. In this example, since the depth is constant, the passage area F is proportional to the passage width H.

[0128] The other configurations are the same as those of the first to fourth embodiments.

[0129] The ionic conductivity κ of the positive electrode passages 80 arranged in the positive electrode tab corresponding portion 21 (particularly the rear end portion 21a of the positive electrode tab corresponding portion 21 opposite the positive electrode tab 30) where the concentration of lithium ions Li+ is likely to be uneven is increased. This is advantageous in suppressing unevenness in the concentration of lithium ions Li+ between the positive electrode foil 10 side and the separator 70 side in the positive electrode active material layer 20.

[0130] Similarly, the ionic conductivity κ of the anode-side passages 90 arranged in the anode-side tab corresponding portion 51 (particularly the rear end portion 51a of the anode-side tab corresponding portion 51 opposite the anode tab 60) where the concentration of lithium ions Li+ is likely to be uneven is increased. This is advantageous in suppressing unevenness in the concentration of lithium ions Li+ between the anode foil 40 side and the separator 70 side in the anode active material layer 50.

[0131] The ionic conductivity κ of the positive electrode side passage 80 arranged in the positive electrode side tab corresponding portion 21, where the concentration of lithium ions Li+ is likely to be uneven, can be easily increased by increasing the passage area F (more specifically, the passage width H).

[0132] Similarly, the ionic conductivity κ of the negative electrode side passage 90 arranged in the negative electrode side tab corresponding portion 51, where the concentration of lithium ions Li+ is likely to be uneven, can be easily increased by increasing the passage area F (more specifically, the passage width H).

[0133] <Other embodiments> Although the present disclosure has been described above with reference to preferred embodiments, such description is not limiting, and it goes without saying that various modifications, substitutions, or combinations are possible.

[0134] In the fourth embodiment, the material with low electrical resistivity ρ that constitutes the positive electrode passages 80 (negative electrode passages 90) may be the material that constitutes the separator .

[0135] In the fifth embodiment, the porosity of the positive electrode side passage 80 (negative electrode side passage 90) arranged in the positive electrode side tab corresponding portion 21 (negative electrode side tab corresponding portion 51) may be higher than the porosity of the positive electrode side passage 80 (negative electrode side passage 90) arranged in the positive electrode side tab non-corresponding portion 22 (negative electrode side tab non-corresponding portion 52).

[0136] In the fifth embodiment, the electrical resistivity of the positive electrode side passage 80 (negative electrode side passage 90) arranged in the positive electrode side tab corresponding portion 21 (negative electrode side tab corresponding portion 51) may be lower than the electrical resistivity of the positive electrode side passage 80 (negative electrode side passage 90) arranged in the positive electrode side tab non-corresponding portion 22 (negative electrode side tab non-corresponding portion 52).

[0137] As a method for increasing the ionic conductivity κ, a method other than the above-mentioned methods may be used.

[0138] The secondary battery 5 may include a wound secondary battery electrode structure 6, or a plurality of stacked secondary battery electrode structures 6, or the like.

[0139] The passages may be present in at least one of the positive electrode active material layer 20 and the negative electrode active material layer 50 .

[0140] In the above embodiment, the first electrode is a positive electrode and the second electrode is a negative electrode, but this is not limiting. The first electrode may be a negative electrode and the second electrode may be a positive electrode.

[0141] The secondary battery 5 may be applied to devices other than the vehicle 1 (for example, a computer, etc.).

[0142] In the above embodiment, the terms front, back, left, right, top, and bottom are defined merely for convenience, and these directions may be determined as appropriate.

[0143] The secondary battery 5 is not limited to a lithium ion secondary battery, but may be, for example, a sodium ion secondary battery. [Example]

[0144] 10 to 12 show simulation data of the distribution of the concentration of lithium ions Li+. FIG. 10 shows a first example corresponding to the first embodiment. FIG. 11 shows a second example corresponding to the fifth embodiment. FIG. 12 shows a comparative example in which neither the positive electrode passage 80 nor the negative electrode passage 90 is present. All of FIGS. 10 to 12 show the state after discharge. The shading of black and white represents the difference in the concentration of lithium ions Li+.

[0145] As shown in FIG. 12, in the comparative example, there is a bias in the concentration of lithium ions Li+ between the positive electrode foil 10 side and the separator 70 side in the positive electrode active material layer 20, and between the negative electrode foil 40 side and the separator 70 side in the negative electrode active material layer 50.

[0146] As shown in FIGS. 10 and 11 , in the first and second examples, the bias in the concentration of lithium ions Li+ is suppressed between the positive electrode foil 10 side and the separator 70 side in the positive electrode active material layer 20, and between the negative electrode foil 40 side and the separator 70 side in the negative electrode active material layer 50, compared to the comparative example.

[0147] As shown in FIGS. 10 and 11 , particularly in the vicinity of the positive electrode-side passages 80 and the negative electrode-side passages 90, the bias in the concentration of lithium ions Li+ is suppressed between the positive electrode foil 10 side and the separator 70 side in the positive electrode active material layer 20, and between the negative electrode foil 40 side and the separator 70 side in the negative electrode active material layer 50.

[0148] As shown in FIG. 11 (Second Example), more notably, in the vicinity of the positive electrode-side passage 80 arranged in the positive electrode-side tab corresponding portion 21 and the negative electrode-side passage 90 arranged in the negative electrode-side tab corresponding portion 51, the bias in the concentration of lithium ions Li+ is suppressed between the positive electrode foil 10 side and the separator 70 side in the positive electrode active material layer 20, and between the negative electrode foil 40 side and the separator 70 side in the negative electrode active material layer 50. [Industrial Applicability]

[0149] The present disclosure is extremely useful and has high industrial applicability because it can be applied to electrode structures for secondary batteries, secondary batteries, and vehicles. [Explanation of symbols]

[0150] 1 vehicle 2 Battery Unit 3 Electric motor 4 wheels 5 Secondary battery 6 Electrode structure for secondary batteries 7 Electrolyte 8 cases 10 Positive electrode foil (first electrode foil) 20 Positive electrode active material layer (first electrode active material layer) 21 Positive electrode tab corresponding part (part) 21a Rear end 22 Positive electrode tab non-compatible part (part) 23 Positive electrode side main body part (part) 30 Positive electrode tab (first electrode tab) 40 Negative electrode foil (second electrode foil) 50 Negative electrode active material layer (second electrode active material layer) 51 Negative electrode tab corresponding part (part) 51a Rear end 52 Negative electrode tab non-compatible part (part) 53 Negative side main body part (part) 60 Negative electrode tab (second electrode tab) 70 Separator 80 Positive electrode passage (first passage) 81 Positive electrode through hole (through hole) 90 Negative electrode passage (second passage) 91 Negative electrode through hole (through hole) 101 Charging circuit 101a external power supply 102 Discharge circuit 102a resistor A Positive electrode (1st electrode) B Negative electrode (second electrode) Li+ lithium ion (ion) e- electronic κ ionic conductivity E space ε Porosity ρ Electrical resistivity F Passage area H Passage width

Claims

1. A first electrode foil; a first electrode active material layer supported on the first electrode foil; A second electrode foil; a second electrode active material layer supported on the second electrode foil; a separator interposed between the first electrode active material layer and the second electrode active material layer, the first electrode active material layer has a first passage extending from the first electrode foil side to the separator side, The electrode structure for a secondary battery, wherein the first passages have a higher ionic conductivity than a portion of the first electrode active material layer other than the first passages.

2. 2 . The electrode structure for a secondary battery according to claim 1 , wherein the first passages have a higher porosity than the portions of the first electrode active material layer other than the first passages.

3. The electrode structure for a secondary battery according to claim 2 , wherein the first passage is formed as a through hole.

4. The electrode structure for a secondary battery according to claim 1 , wherein the first passage is made of the same material as the separator.

5. 2. The electrode structure for a secondary battery according to claim 1, wherein the first passages are made of a material having a lower electrical resistivity than the portions of the first electrode active material layer other than the first passages.

6. a first electrode tab connected to the first electrode foil; The electrode structure for a secondary battery according to claim 1 , wherein the first passage is disposed in a portion corresponding to the first electrode tab.

7. 7. The electrode structure for a secondary battery according to claim 6, wherein the first passage arranged in the portion corresponding to the first electrode tab has a higher ionic conductivity than the first passage arranged in the portion other than the portion corresponding to the first electrode tab.

8. 8. The electrode structure for a secondary battery according to claim 7, wherein the first passage arranged in the portion corresponding to the first electrode tab has a larger passage area than the first passage arranged in the portion other than the portion corresponding to the first electrode tab.

9. the second electrode active material layer has a second passage extending from the second electrode foil side to the separator side, 6. The electrode structure for a secondary battery according to claim 1, wherein the second passages have a higher ionic conductivity than a portion of the second electrode active material layer other than the second passages.

10. The electrode structure for a secondary battery according to any one of claims 1 to 5; An electrolyte; a case that accommodates the secondary battery electrode structure and the electrolyte solution.

11. The secondary battery according to claim 10; an electric motor driven by the secondary battery; and a wheel driven by the electric motor.

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