WO2023042280A1 - 電極、電池セル、セルスタック、電池システム、及び電極の製造方法 - Google Patents
電極、電池セル、セルスタック、電池システム、及び電極の製造方法 Download PDFInfo
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- WO2023042280A1 WO2023042280A1 PCT/JP2021/033821 JP2021033821W WO2023042280A1 WO 2023042280 A1 WO2023042280 A1 WO 2023042280A1 JP 2021033821 W JP2021033821 W JP 2021033821W WO 2023042280 A1 WO2023042280 A1 WO 2023042280A1
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- Y02E60/30—Hydrogen technology
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Definitions
- the present disclosure relates to electrodes, battery cells, cell stacks, battery systems, and methods of manufacturing electrodes.
- Patent Document 1 discloses the following.
- a roll of carbon fiber nonwoven fabric is prepared.
- the width of the carbon fiber nonwoven fabric is 1.2m to 1.5m.
- the length of the carbon fiber nonwoven fabric is 20m to 70m.
- the roll-shaped carbon fiber nonwoven fabric runs by being unwound by a winder.
- the running carbon fiber nonwoven fabric passes between a pair of vertically facing transport rollers.
- the carbon fiber nonwoven fabric passed between the pair of transport rollers is cut by a band knife arranged near the outlet of the pair of transport rollers. This cutting produces two layers of carbon fiber nonwoven of uniform thickness.
- the two carbon fiber nonwoven fabric layers thus produced are respectively wound by different winding machines.
- the electrodes of the present disclosure are An electrode for use in a battery system, comprising: Equipped with a sheet made of nonwoven fabric containing multiple carbon fibers, The sheet has a first surface and a second surface facing each other in a direction along the thickness of the sheet, The plurality of carbon fibers includes a first carbon fiber, The first carbon fiber has at least one of a cut surface facing the first surface and a cut surface facing the second surface, The width of the sheet is 1000 mm or less, The sheet has a length of 2000 mm or less.
- a battery cell of the present disclosure includes an electrode of the present disclosure.
- a cell stack of the present disclosure includes a plurality of battery cells of the present disclosure.
- the battery system of the present disclosure includes the battery cell of the present disclosure or the cell stack of the present disclosure.
- a method for manufacturing an electrode of the present disclosure includes: A method for manufacturing an electrode used in a battery system, comprising: preparing a sheet-shaped first electrode material having a width of 1000 mm or less and a length of 2000 mm or less and made of a nonwoven fabric containing a plurality of carbon fibers; A step of cutting the first electrode material to produce the electrode, The step of fabricating the electrode includes: feeding the first electrode material to a cutting tool by rotation of a first roller and a second roller sandwiching the first electrode material; and slicing the first electrode material with the cutting tool so that the thickness of the first electrode material is reduced.
- FIG. 1 is a schematic perspective view showing electrodes of the embodiment.
- FIG. 2 is a schematic diagram showing a part of the II-II section of FIG.
- FIG. 3 is a schematic cross-sectional view schematically showing a cross section of carbon fibers that constitute the electrode of the embodiment.
- FIG. 4 is an explanatory diagram showing measurement points for measuring the thickness of the electrode according to the embodiment.
- FIG. 5 is an explanatory diagram showing measurement points for measuring the thickness of the electrode according to the embodiment.
- FIG. 6 is a perspective view for explaining the method of manufacturing the electrode of the embodiment.
- FIG. 7 is a top view for explaining the method for manufacturing the electrode of the embodiment.
- FIG. 8 is a cross-sectional view for explaining the method for manufacturing the electrode of the embodiment.
- FIG. 9 is a schematic configuration diagram of the redox flow battery system of the embodiment.
- FIG. 10 is a schematic configuration diagram of a cell stack included in the redox flow battery system of the embodiment.
- One of the purposes of the present disclosure is to provide an electrode with small variations in thickness.
- An object of the present disclosure is to provide a battery cell including the electrode.
- An object of the present disclosure is to provide a cell stack including the battery cells described above.
- An object of the present disclosure is to provide a battery system including the battery cell or the cell stack.
- An object of the present disclosure is to provide an electrode manufacturing method capable of manufacturing an electrode with small variations in thickness.
- the electrodes of the present disclosure have small thickness variations.
- the battery cell, cell stack, and battery system of the present disclosure can easily increase current efficiency and reduce cell resistivity.
- the electrode manufacturing method of the present disclosure can manufacture electrodes with small variations in thickness.
- An electrode for use in a battery system comprising: Equipped with a sheet made of nonwoven fabric containing multiple carbon fibers, The sheet has a first surface and a second surface facing each other in a direction along the thickness of the sheet, The plurality of carbon fibers includes a first carbon fiber, The first carbon fiber has at least one of a cut surface facing the first surface and a cut surface facing the second surface, The width of the sheet is 1000 mm or less, The sheet has a length of 2000 mm or less.
- the electrode containing the first carbon fibers is manufactured by the electrode manufacturing method described below.
- the electrode manufacturing method is a method of manufacturing an electrode by slicing the first electrode material so that the thickness of the first electrode material becomes thin.
- the width of the sliced first electrode material is 1000 mm or less, and the length of the first electrode material is 2000 mm or less. That is, the width of the first electrode material is narrow and the length of the first electrode material is short.
- the rotation of the first roller and the second roller sandwiching the first electrode material feeds the first electrode material to a cutting tool that slices the first electrode material.
- the first electrode material is sliced without substantially applying tension to the first electrode material.
- substantially no tension acts means that tension associated with winding the first electrode material downstream of the first roller and the second roller does not act.
- tension acts on the first electrode material, and the produced electrode has a first thickness variation described below that exceeds 25%. . It is permissible for the tension resulting from being sandwiched between the first roller and the second roller to act on the first electrode material. Therefore, in the electrode manufacturing method, the same position in the thickness direction of the first electrode material is likely to be cut along the width direction and the length direction of the first electrode material.
- the electrodes facilitate construction of battery cells, cell stacks, and battery systems with excellent battery performance. Specifically, the electrodes facilitate construction of battery cells, cell stacks, and battery systems with high current efficiency and low cell resistivity.
- the sheet preferably has an average thickness of 0.5 mm or more and 3 mm or less.
- a sheet with an average thickness of 0.5 mm or more facilitates construction of battery cells, cell stacks, and RF battery systems with excellent battery performance. Moreover, a sheet having an average thickness of 0.5 mm or more has excellent mechanical strength.
- the carbon fiber nonwoven fabric having a wide width and a long length is cut while tension is applied to the carbon fiber nonwoven fabric. Since the technique of Patent Document 1 described above is a method for producing two sheets of electrodes having a uniform thickness, the thickness of the carbon fiber nonwoven fabric is also reduced when an electrode having a small thickness is produced. As the thickness of the carbon fiber nonwoven fabric becomes thinner, it becomes more difficult to uniformly apply the tension in the width direction of the carbon fiber nonwoven fabric. Therefore, the thinner the carbon fiber nonwoven fabric, the more difficult it is to cut the same position in the thickness direction of the carbon fiber nonwoven fabric along the width direction of the carbon fiber nonwoven fabric.
- the sheet has a length of 500 mm or more.
- Sheets with a length of 500 mm or more facilitate construction of high-power battery cells, cell stacks, and battery systems.
- Variation in thickness of the sheet is preferably 25% or less.
- the variation in thickness is 25% or less, the battery performance of the electrode tends to be uniform over the entire area of the electrode. This variation in thickness is the first variation in thickness, which will be described later.
- Variation in basis weight of the sheet is preferably 25% or less.
- variation in basis weight is 25% or less, the electrical conductivity of the electrode and the fluidity of the electrolytic solution tend to be uniform over the entire electrode.
- This variation in basis weight refers to the first variation in basis weight, which will be described later.
- the basis weight of the sheet is 50 g/m 2 or more and 350 g/m 2 or less.
- a sheet having a basis weight of 50 g/m 2 or more tends to increase contact points between carbon fibers, and thus tends to increase conductivity.
- a sheet having a basis weight of 350 g/m 2 or less easily secures voids, and thus has excellent flowability of the electrolytic solution.
- the plurality of carbon fibers may include carbon fibers having a plurality of pleats on the surface.
- the surface area of the carbon fiber tends to increase. Carbon fibers with a large surface area tend to increase the reaction area in contact with the electrolytic solution. Therefore, the reactivity between the electrode and the electrolyte is improved.
- the density of the plurality of carbon fibers is 1.5 g/cm 3 or more and 2.2 g/cm 3 or less; It is preferable that the sheet has a porosity of 60% or more and 99% or less.
- the density of the carbon fiber is 1.5 g/cm 3 or more, the conductive component is large. Electrodes containing this carbon fiber facilitate construction of battery cells with low internal resistance. If the density of the carbon fiber is 2.2 g/cm 3 or less, the stiffness of the carbon fiber is not too high. An electrode containing this carbon fiber facilitates construction of a battery cell in which the diaphragm is less likely to be damaged.
- the porosity of the sheet is 60% or more, there are more voids than a sheet with a porosity of less than 60%. This sheet is excellent in electrolyte solution flowability. If the porosity of the sheet is 99% or less, the electrode is excellent in battery reactivity.
- a battery cell according to one aspect of the present disclosure is The electrode according to any one of (1) to (8) above is provided.
- the battery cell includes electrodes with small variations in thickness, it is easy to increase the current efficiency and reduce the cell resistivity.
- a cell stack according to one aspect of the present disclosure includes: A plurality of battery cells according to (9) are provided.
- the cell stack includes a plurality of battery cells, it is easy to increase current efficiency and reduce cell resistivity.
- a battery system according to an aspect of the present disclosure includes: The battery cell according to (9) above or the cell stack according to (10) above is provided.
- the battery system includes the battery cells or the cell stack, it is easy to increase the current efficiency and reduce the cell resistivity.
- a method for manufacturing an electrode according to one aspect of the present disclosure includes: A method for manufacturing an electrode used in a battery system, comprising: preparing a sheet-shaped first electrode material having a width of 1000 mm or less and a length of 2000 mm or less and made of a nonwoven fabric containing a plurality of carbon fibers; A step of cutting the first electrode material to produce the electrode, The step of fabricating the electrode includes: feeding the first electrode material to a cutting tool by rotation of a first roller and a second roller sandwiching the first electrode material; and slicing the first electrode material with the cutting tool so that the thickness of the first electrode material is reduced.
- the manufacturing method described above can manufacture electrodes with small variations in thickness.
- the width of the first electrode material to be sliced is 1000 mm or less, and the length of the first electrode material is 2000 mm or less. That is, the width of the first electrode material is narrow and the length of the first electrode material is short.
- the rotation of the first roller and the second roller sandwiching the first electrode material feeds the first electrode material to the cutting tool for slicing the first electrode material. That is, in the manufacturing method described above, the first electrode material is sliced without substantially applying tension to the first electrode material. Therefore, the manufacturing method described above facilitates cutting at the same position in the thickness direction of the first electrode material along the width direction and the length direction of the first electrode material.
- the first electrode material may be sliced so that the electrode has an average thickness of 0.5 mm or more and 3 mm or less.
- an electrode with small variations in thickness can be manufactured even if the average thickness satisfies the above range.
- the first electrode material In the step of preparing the first electrode material, preparing the first electrode material having a thickness more than twice the average thickness of the electrode; In the step of slicing the first electrode material, the first electrode material may be sliced so as to produce the electrodes and a second electrode material having a thickness greater than the average thickness of the electrodes.
- the thickness of the fabricated second electrode material is more than 1 times the average thickness of the electrodes, so that at least one electrode can be obtained by slicing the second electrode material again as the first electrode material. This is because it can be manufactured. That is, in the above embodiment, the slicing step can be performed two or more times.
- the method of slicing the first electrode material unevenly so as to fabricate electrodes with different thicknesses and the second electrode material is a method in which two electrodes with uniform thickness are fabricated.
- the uneven slicing method requires that the thickness of the first electrode material be more than twice the average thickness of the electrode, whereas the even slicing method requires the thickness of the first electrode material This is because the thickness must be 2 n times the average thickness of the electrodes. n is an integer of 1 or more.
- the first electrode material In the step of preparing the first electrode material, preparing the first electrode material having a thickness that is an integral multiple of three or more times the average thickness of the electrode; In the step of slicing the first electrode material, the first electrode material may be sliced so as to produce the electrodes and a second electrode material having a thickness greater than the average thickness of the electrodes.
- the thickness of the manufactured second electrode material has a thickness that is an integral multiple of two or more times the thickness of the electrode. This is because two electrodes can be produced. That is, in the above embodiment, the slicing step can be performed two or more times.
- the electrode can be produced without leaving the first electrode material.
- the above-described configuration reduces the carbon fiber shavings generated by cutting to the first roller. And it is difficult to clog between the second roller and the first electrode material.
- the step of feeding the first electrode material to the cutting tool it is preferable to feed the first electrode material to the cutting tool while restricting displacement of the first electrode material in the width direction by a guide.
- the first electrode material can be easily moved substantially straight toward the gap between the first roller and the second roller, so it is easy to manufacture electrodes with small variations in thickness.
- Batteries are redox flow batteries, fuel cells, lithium-ion batteries, and other batteries that use carbon materials as electrodes.
- the following battery system will be described using a redox flow battery system as an example.
- a redox flow battery system may be referred to as an RF battery system.
- the same reference numerals in the drawings indicate the same names.
- FIG. Electrode 1 is used in RF battery system 100, which will be described later with reference to FIG.
- the electrode 1 comprises a sheet 2 made of nonwoven fabric containing a plurality of carbon fibers.
- One of the features of the electrode 1 of this embodiment is to satisfy the following requirement (a1) and requirement (b1).
- (a1) As shown in FIG. 1, the sheet 2 has a specific width Wa and a specific length La.
- (b1) the plurality of carbon fibers have specific first carbon fibers;
- the electrode 1 of this embodiment shown in FIG. 1 constitutes at least one of a positive electrode 4P and a negative electrode 4N, which will be described later with reference to FIG.
- the electrode 1 contributes to the battery reaction in the RF battery system 100 shown in FIG.
- the sheet 2 contains carbon fiber as a main component. Having carbon fiber as the main component means that the ratio of the weight of carbon fiber to the weight of sheet 2 is 50% or more.
- the weight ratio of the carbon fibers to the weight of the sheet 2 is preferably 60% or more, particularly 70% or more.
- the sheet 2 is a nonwoven fabric containing a plurality of carbon fibers. A nonwoven fabric is made by entangling independent carbon fibers. A plurality of carbon fibers form a three-dimensional network structure. Gaps are provided between the carbon fibers, that is, between the meshes.
- the sheet 2 may contain at least one of binder, carbon particles, catalyst, hydrophilic material and hydrophobic material. The binder binds the carbon fibers together.
- the carbon particles increase the surface area of sheet 2 . Catalysts promote cell reactions.
- the sheet 2 has a first surface 21 and a second surface 22 facing each other in the direction along the thickness of the sheet 2, as shown in FIG. At least one of the first surface 21 and the second surface 22 is a cut surface.
- the plurality of carbon fibers includes the first carbon fiber.
- the first carbon fiber has at least one of a cut surface facing the first surface 21 and a cut surface facing the second surface 22 .
- An example of the number of first carbon fibers is plural. That is, when the first surface 21 is a cut surface, a plurality of cut surfaces of the first carbon fibers are arranged side by side on the first surface 21 .
- the second surface 22 is also a cut surface like the first surface 21 , the cut surfaces of the plurality of first carbon fibers are arranged on the second surface 22 like the first surface 21 .
- the plurality of carbon fibers further includes a second carbon fiber.
- Each of the second carbon fibers does not have both a cut surface facing the first surface 21 and a cut surface facing the second surface 22, unlike the first carbon fibers.
- the second surface 22 is a non-cut surface
- the second surface 22 faces the middle portion of the second carbon fiber in the longitudinal direction.
- the end faces of the second carbon fibers are not aligned with the second surface 22 and are randomly arranged.
- the cut surfaces of the plurality of first carbon fibers are not aligned on the second surface 22 .
- planar shape The planar shape of the sheet 2 is rectangular as shown in FIG.
- the planar shape is the shape when the first surface 21 or the second surface 22 is viewed from the thickness direction of the sheet 2 .
- the term "rectangular shape" as used herein includes a rectangular shape and a square shape.
- an example of the ratio of the long side to the short side of the sheet 2 is more than 1 and 5 or less. The above ratio may also be greater than 1 and no greater than 3, in particular greater than 1 and no greater than 2.
- the width Wa of the sheet 2 is 1000 mm or less. Since the width Wa is 1000 mm or less, variations in the thickness of the sheet 2 are small.
- the width Wa maintains the width Wb of the first electrode material 11 prepared in the electrode manufacturing method of the embodiment described later with reference to FIG. 7 and the like.
- the sheet 2 with a width Wa of 1000 mm is produced using the first electrode material 11 with a width Wb of 1000 mm.
- the width Wb is 1000 mm or less, it is easy to cut the same position in the thickness direction of the first electrode material 11 along the width direction of the first electrode material 11 in the electrode manufacturing method of the embodiment. Therefore, in the electrode manufacturing method of the embodiment, a sheet 2 having a small variation in thickness can be obtained.
- the width Wa is also less than or equal to 750 mm, especially less than or equal to 500 mm.
- An example of the lower limit of the width Wa is 200 mm.
- a sheet 2 having a width Wa of 200 mm or more facilitates construction of high-output battery cells, cell stacks, and RF battery systems.
- the width Wa is 200 mm or more and 1000 mm or less, further 300 mm or more and 750 mm or less, and particularly 350 mm or more and 500 mm or less.
- the width Wa is the maximum width of the sheet 2 .
- the length La of the sheet 2 is 2000 mm or less. Since the length La is 2000 mm or less, variations in the thickness of the sheet 2 are small. The length La is maintained at the length Lb of the first electrode material 11 shown in FIG.
- the sheet 2 with a length La of 2000 mm is produced using the first electrode material 11 with a length Lb of 2000 mm.
- the length Lb is 2000 mm or less, it is easy to cut the same position in the thickness direction of the first electrode material 11 along the length direction of the first electrode material 11 in the electrode manufacturing method of the embodiment. Therefore, in the electrode manufacturing method of the embodiment, a sheet 2 having a small variation in thickness can be obtained. Variation in the thickness of the sheet 2 tends to decrease as the length La decreases.
- the length La is also less than or equal to 1500 mm, in particular less than or equal to 1000 mm.
- An example of the lower limit of the length La is 500 mm.
- a sheet 2 having a length La of 500 mm or more facilitates construction of high-output battery cells, cell stacks, and RF battery systems.
- the length La is 500 mm or more and 2000 mm or less, further 650 mm or more and 1500 mm or less, and particularly 750 mm or more and 1000 mm or less.
- the length La may be 500 mm or more and 1000 mm or less.
- Length La is the maximum length of sheet 2 .
- An example of the average thickness of the sheet 2 is 0.5 mm or more and 3 mm or less.
- the sheet 2 having an average thickness of 0.5 mm or more facilitates construction of battery cells, cell stacks, and RF battery systems with excellent battery performance.
- the sheet 2 having an average thickness of 0.5 mm or more has excellent mechanical strength.
- a sheet 2 having an average thickness of 3 mm or less facilitates construction of thin battery cells and cell stacks. Therefore, the sheet 2 having an average thickness of 3 mm or less facilitates construction of a compact RF battery system.
- An example of the average thickness of the sheet 2 is 0.5 mm or more and 2.5 mm or less, further 0.6 mm or more and 2.0 mm or less, and particularly 0.8 mm or more and 1.5 mm or less.
- the average thickness of the sheet 2 is obtained as follows.
- the number of thickness measurement points shall be 6 or more.
- An example of the measurement points is at least the first intersection point P1 to the sixth intersection point P6, as shown in FIG. 4 or FIG.
- the first intersection point P1 is the intersection point between the first virtual line V1 and the third virtual line V3.
- the second intersection point P2 is the intersection point between the first virtual line V1 and the fourth virtual line V4.
- a third intersection point P3 is an intersection point between the second virtual line V2 and the third virtual line V3.
- a fourth intersection point P4 is an intersection point between the second virtual line V2 and the fourth virtual line V4.
- the fifth intersection P5 is the intersection of the fifth virtual line V5 and the third virtual line V3.
- the fifth intersection P5 is the intersection of the first virtual line V1 and the fifth virtual line V5.
- the sixth intersection P6 is the intersection of the fifth virtual line V5 and the fourth virtual line V4.
- the sixth intersection P6 is the intersection of the second virtual line V2 and the fifth virtual line V5.
- the first imaginary line V1 is a straight line along the width direction of the sheet 2, and the distance from the first short side of the sheet 2 to the first imaginary line V1 is at least La ⁇ 0.1 times the length La ⁇ The straight line is 0.2 times or less.
- the second imaginary line V2 is a straight line along the width direction of the sheet 2, and the distance from the second short side of the sheet 2 to the second imaginary line V2 is the length La ⁇ 0.1 times or more the length La ⁇ The straight line is 0.2 times or less.
- the distance from the first short side to the first virtual line V1 is the same as the distance from the second short side to the second virtual line V2.
- the third imaginary line V3 is a straight line along the length direction of the sheet 2, and the distance from the first long side of the sheet 2 to the third imaginary line V3 is not less than the width Wa ⁇ 0.1 times the width Wa ⁇ 0. .2 times or less.
- the fourth imaginary line V4 is a straight line along the length direction of the sheet 2, and the distance from the second long side of the sheet 2 to the fourth imaginary line V4 is width Wa ⁇ 0.1 times or more width Wa ⁇ 0. .2 times or less.
- the distance from the first long side to the third virtual line V3 is the same as the distance from the second long side to the fourth virtual line V4.
- the fifth virtual line V5 is a straight line that divides evenly between the first virtual line V1 and the second virtual line V2.
- the fifth virtual line V5 is a straight line that divides evenly between the third virtual line V3 and the fourth virtual line V4.
- the above measurement points should be selected from the above range according to the width and length of the sheet 2 so that 6 or more measurement points can be collected.
- a plurality of intersection points are arranged at equal intervals between the first intersection point P1 and the third intersection point P3 on the third virtual line V3, and the intersection between the second intersection point P2 and the fourth intersection point P4 on the fourth virtual line V4
- a plurality of intersection points are arranged at regular intervals.
- a plurality of intersection points are arranged at equal intervals between the first intersection point P1 and the second intersection point P2 on the first virtual line V1, and the intersection between the third intersection point P3 and the fourth intersection point P4 on the second virtual line V2.
- a plurality of intersection points are arranged at regular intervals.
- two or more virtual lines that equally divide the first virtual line V1 and the second virtual line V2 are taken.
- two or more virtual lines that equally divide the third virtual line V3 and the fourth virtual line V4 are taken.
- the thickness at each intersection can be obtained by measuring in accordance with JIS L 1096:2010 A method (JIS method). Specifically, using a commercially available thickness measuring device, the thickness of each intersection is measured under a constant time and a constant pressure. A contact-type digital synex gauge SMD-565J-L manufactured by Teclock is used as a thickness measuring device. The above time shall be 10 seconds. The above pressure is 0.7 kPa. Let the average value of all measured thicknesses be the average thickness of the sheet 2 .
- a first example of variation in the thickness of the sheet 2 is 25% or less.
- the first variation in thickness is obtained by "(standard deviation of thickness/average value of thickness) x 100".
- the standard deviation of thickness is a value based on the average thickness of the sheet 2 and the measured value at each intersection as described above.
- the average thickness is the average thickness of the sheet 2 described above. If the first variation in thickness is 25% or less, the battery performance of electrode 1 tends to be uniform over the entire area of electrode 1 .
- the first variation in thickness is preferably as small as possible.
- An example of the lower limit of the first variation in thickness is practically 2%.
- the first thickness variation is 2% or more and 25% or less, further 5% or more and 20% or less, and particularly 6% or more and 15% or less.
- the first variation in thickness may be between 2% and 15%.
- a second example of variation in the thickness of the sheet 2 is 30% or less.
- the second variation in thickness is obtained by " ⁇ (maximum thickness - minimum thickness)/average thickness ⁇ x 100".
- the maximum thickness value is the maximum thickness among all the thicknesses at the intersections measured to obtain the average thickness of the sheet 2 described above.
- the minimum thickness refers to the minimum thickness among all the thicknesses at the intersections. If the second thickness variation is 30% or less, the battery performance of the electrode 1 tends to be uniform over the entire area of the electrode 1 .
- the second variation in thickness is preferably as small as possible.
- An example of the lower limit of the second variation in thickness is practically 3%.
- the second thickness variation is 3% or more and 30% or less, further 5% or more and 25% or less, and particularly 6% or more and 20% or less.
- the first variation in basis weight of the sheet 2 is 25% or less.
- the first variation in basis weight is obtained by "(standard deviation of basis weight/average value of basis weight) x 100".
- the standard deviation of the basis weight is a value based on the average value of the basis weight and the measured value of the basis weight of each measurement piece.
- the average weight per unit area is obtained as follows. Six or more measurement strips are cut out from one sheet 2. Each measurement piece has a square shape centered on each of the above intersections. The length of one side of each measuring piece shall be 30 mm.
- the basis weight of each measurement piece is obtained by measuring the weight per unit area. Take the average value of all the basis weights obtained.
- the conductivity of the electrode 1 and the fluidity of the electrolytic solution tend to be uniform over the entire area of the electrode 1 . It is preferable that the first variation in basis weight is as small as possible.
- An example of the lower limit of the first variation in basis weight is practically 2%.
- the first variation in basis weight is 2% or more and 25% or less, further 5% or more and 20% or less, and particularly 6% or more and 15% or less.
- the first variation in basis weight may be 2% or more and 15% or less.
- An example of a second variation in basis weight of the sheet 2 is 50 g/m 2 or less.
- the second variation in basis weight is obtained by "maximum basis weight - minimum basis weight".
- the maximum basis weight refers to the maximum basis weight among all the basis weights of the above-mentioned measurement pieces measured to obtain the above-mentioned average basis weight.
- the minimum weight per unit area refers to the minimum weight per unit area among all the above-described measurement pieces. If the second variation in the basis weight is 50 g/m 2 or less, the conductivity of the electrode 1 and the flowability of the electrolytic solution tend to be uniform over the entire area of the electrode 1 .
- the second variation in basis weight is preferably as small as possible.
- An example of the lower limit of the second variation in basis weight is 2 g/m 2 .
- the second variation of basis weight is 2 g/m 2 or more and 50 g/m 2 or less, further 4 g/m 2 or more and 35 g/m 2 or less, and particularly 5 g/m 2 or more and 20 g/m 2 or less.
- the basis weight of the sheet 2 is 50 g/m 2 or more and 350 g/m 2 or less.
- the basis weight of the sheet 2 is the basis weight of the entire sheet 2 .
- the basis weight is obtained by measuring the weight per unit area.
- the sheet 2 having a basis weight of 50 g/m 2 or more tends to increase the contact points between the carbon fibers, and thus tends to increase the conductivity.
- the sheet 2 having a basis weight of 350 g/m 2 or less easily secures voids, and thus has excellent flowability of the electrolytic solution.
- the basis weight of the sheet 2 is further 70 g/m 2 or more and 300 g/m 2 or less, particularly 80 g/m 2 or more and 250 g/m 2 or less.
- porosity An example of the porosity of the sheet 2 is 60% or more and 99% or less. If the porosity of the sheet 2 is 60% or more, it has more voids than a sheet with a porosity of less than 60%. This sheet 2 is excellent in electrolyte solution flowability. If the porosity of the sheet 2 is 99% or less, the electrode 1 is excellent in battery reactivity.
- the porosity of the sheet 2 is 60% or more and 95% or less, further 65% or more and 94% or less, and particularly 75% or more and 90% or less. The porosity is determined by "100 ⁇ [ ⁇ basis weight (g/m 2 )/average thickness (mm)/1000/density (g/cm 3 ) ⁇ 100]". Density is the density of carbon fibers. The density of carbon fibers will be described later.
- the plurality of carbon fibers includes a carbon fiber 30 having a plurality of pleats 35 on its surface in this embodiment, as shown in FIG. FIG. 3 schematically shows the contour of the cross section of the carbon fiber 30.
- the carbon fiber 30 has a corrugated uneven structure on its surface. Having a plurality of pleats 35 on the surface of the carbon fiber 30 facilitates increasing the surface area of the carbon fiber 30 .
- the carbon fiber 30 having a large surface area tends to increase the reaction area in contact with the electrolytic solution. Therefore, the reactivity between the electrode 1 and the electrolyte is improved.
- the cross-sectional shape of the carbon fibers 30 is an irregular cross-sectional shape.
- At least one of the above-described first carbon fibers and the above-described second carbon fibers may have pleats 35 .
- the plurality of carbon fibers may include carbon fibers that do not have pleats 35 . Also, not all of the plurality of carbon fibers may have the pleats 35 .
- the cross-sectional shape of the carbon fibers without the pleats 35 may be, for example, circular or elliptical.
- the circumference L1 is the circumference of the cross section of the carbon fiber 30 .
- the perimeter L2 is the perimeter of the imaginary rectangle R circumscribing the cross section of the carbon fiber 30 .
- the circumference ratio L1/L2 is more than 1, it is possible to secure a sufficient reaction area where the carbon fibers 30 and the electrolytic solution are in contact. Therefore, the reactivity between the electrode 1 and the electrolytic solution is improved.
- the surface area of the carbon fiber 30 is proportional to the circumference L1.
- An example of the circumference ratio L1/L2 is 1.1 or more.
- the perimeter ratio L1/L2 When the perimeter ratio L1/L2 is large, the number of pleats 35 tends to increase. When the number of pleats 35 increases, the pleats 35 may stick together or the gap between the pleats 35 may narrow. In that case, it becomes difficult for the electrolytic solution to enter the gaps between the pleats 35 . Therefore, it may become difficult to obtain the effect of increasing the reaction area between the electrode 1 and the electrolytic solution.
- One example of the upper limit of the circumference ratio L1/L2 is two. If the circumference ratio L1/L2 is 2 or less, it is easy to secure a sufficient gap between the pleats 35 . Therefore, it becomes easier for the electrolyte to enter the gaps between the pleats 35 .
- An example of the circumference ratio L1/L2 is 1.8 or less, further 1.6 or less, and 1.4 or less.
- the circumference ratio L1/L2 is more than 1 and 2 or less, more than 1.1 and 1.8 or less, more than 1.1 and 1.6 or less, and particularly more than 1.1 and 1.4 or less.
- the circumference L1 is obtained as follows.
- a cross section of the electrode 1 is observed with an optical microscope or a scanning electron microscope (SEM).
- a cross section of the electrode 1 is a cross section cut along the thickness direction of the electrode 1 .
- the outline of the cross section of the carbon fiber 30 is extracted from the cross section observation image obtained by this observation.
- the total length of the extracted contour is measured by image analysis.
- the method of obtaining the virtual rectangle R is as follows.
- the contour of the cross section of the carbon fiber 30 is extracted from the cross section observed image.
- a virtual rectangle R is defined by a first set of parallel lines and a second set of parallel lines.
- the first pair of parallel lines is a pair of parallel lines having the minimum distance between the pair of parallel lines sandwiching the outline of the carbon fiber 30 .
- the second pair of parallel lines is a pair of parallel lines that intersect the first pair of parallel lines and sandwich the outline of the carbon fiber 30, and the distance between the pair of parallel lines is the maximum distance. be.
- the perimeter L2 is "the length of the short side of the virtual rectangle R a ⁇ 2+the length of the long side of the virtual rectangle R b ⁇ 2".
- the circumference ratio L1/L2 is an average value measured as follows. A cross-sectional circumference L1 of each of the plurality of carbon fibers 30 is measured. A virtual rectangle R of the cross section of each of the plurality of carbon fibers 30 is obtained, and the circumference L2 of each virtual rectangle R is measured. Then, the circumference ratio L1/L2 of each carbon fiber 30 is calculated. Find the average value of all circumference ratios L1/L2.
- the number of carbon fibers 30 to be measured is, for example, 3 or more, and further 5 or more.
- Area ratio Sa/Sb An example of the area ratio Sa/Sb between the area Sa and the area Sb is 0.5 or more and 0.8 or less.
- the area Sa is the cross-sectional area of the carbon fiber 30 .
- the area Sb is the area of the imaginary rectangle R circumscribing the cross section of the carbon fiber 30 .
- a cross section of the carbon fiber 30 is a cross section when the electrode 1 is cut along the thickness direction of the electrode 1 .
- the area ratio Sa/Sb When the area ratio Sa/Sb is 0.5 or more, it is easy to sufficiently secure the strength of the carbon fibers 30 . Therefore, the strength of the electrode 1 is less likely to decrease.
- the larger the area ratio Sa/Sb the narrower the gap between the folds 35 becomes.
- the area ratio Sa/Sb is 0.8 or less, it is easy to sufficiently secure the gap between the pleats 35 . Therefore, it becomes difficult for the electrolyte to enter the gaps between the folds 35 . Therefore, the reaction area between the electrode 1 and the electrolytic solution can be ensured.
- An example of the area ratio Sa/Sb is 0.55 or more and 0.75 or less, and particularly 0.55 or more and 0.7 or less.
- An example of the area Sa is, for example, 20 ⁇ m 2 or more and 320 ⁇ m 2 or less, further 30 ⁇ m 2 or more and 300 ⁇ m 2 or less, and particularly 30 ⁇ m 2 or more and 90 ⁇ m 2 or less.
- the area Sa can be measured by image analysis of the cross-sectional observation image described above.
- the area ratio Sa/Sb is an average value measured as follows.
- the cross-sectional area Sa of each of the plurality of carbon fibers 30 is measured.
- the virtual rectangle R of the cross section of each of the plurality of carbon fibers 30 is obtained, and the area Sb of each virtual rectangle R is measured.
- the area ratio Sa/Sb of each carbon fiber 30 is calculated. Find the average value of all the area ratios Sa/Sb.
- the number of carbon fibers 30 to be measured is, for example, 3 or more, and further 5 or more.
- An example of the long diameter of the carbon fibers 30 is 5 ⁇ m or more and 20 ⁇ m or less.
- the major diameter of the carbon fiber 30 corresponds to the length b of the long side of the imaginary rectangle R.
- the long diameter of the carbon fibers 30 is 5 ⁇ m or more, the strength of the carbon fibers 30 can be easily secured, and a decrease in the strength of the electrode 1 can be suppressed.
- Carbon fibers 30 are thin because the major axis of carbon fibers 30 is 20 ⁇ m or less. Therefore, the carbon fibers 30 have flexibility. Therefore, the carbon fibers 30 are less likely to stick into a diaphragm 4M, which will be described later with reference to the upper diagram of FIG.
- the long diameter of the carbon fibers 30 is 15 ⁇ m or less.
- the short diameter of the carbon fiber 30 is equal to or less than the long diameter.
- the minor axis of the carbon fiber 30 corresponds to the length a of the short side of the imaginary rectangle R.
- An example of the short diameter of the carbon fibers 30 is 2 ⁇ m or more and 15 ⁇ m or less.
- the short diameter and long diameter of the carbon fiber 30 are measured as follows. A virtual rectangle R of the cross section of each of the plurality of carbon fibers 30 is obtained. The short side length a and the long side length b of each virtual rectangle R are measured. Let the average value of the length a of all the short sides be the short diameter of the carbon fiber 30 . Let the average value of the length b of all the long sides be the length of the carbon fiber 30 .
- the number of carbon fibers 30 to be measured is, for example, 3 or more, and further 5 or more.
- the carbon fibers 30 are obtained by burning and carbonizing organic fibers.
- the carbon fiber 30 having a plurality of pleats 35 can be produced by firing an organic fiber having a modified cross section with a plurality of pleats formed on the surface.
- the organic fibers can change the cross-sectional shape of the fibers depending on the shape of the nozzle hole.
- the density of carbon fibers is 1.5 g/cm 3 or more and 2.2 g/cm 3 or less. If the density of the carbon fiber is 1.5 g/cm 3 or more, the conductive component is large. The electrode 1 containing this carbon fiber facilitates construction of a battery cell with low internal resistance. If the density of the carbon fiber is 2.2 g/cm 3 or less, the stiffness of the carbon fiber is not too high. The electrode 1 containing this carbon fiber facilitates construction of a battery cell in which a diaphragm 4M, which will be described later with reference to the upper diagram of FIG. 10, is less likely to be damaged.
- the density of the carbon fibers is further between 1.7 g/cm 3 and 2.1 g/cm 3 and especially between 1.8 g/cm 3 and 2.0 g/cm 3 .
- the density of carbon fibers is obtained by measuring in accordance with JIS R 7603:1999 A method: liquid replacement method.
- tensile strength An example of the tensile strength of the sheet 2 is 40 kPa or more and 300 kPa or less. A sheet 2 having a tensile strength of 40 kPa or more is excellent in strength. A sheet 2 having a tensile strength of 300 kPa or less tends to suppress damage to the diaphragm 4M. The tensile strength of the sheet 2 is further 60 kPa or more and 200 kPa or less, particularly 70 kPa or more and 150 kPa or less. The tensile strength of the sheet 2 is obtained by measuring in accordance with JIS L 1913:2010.
- the electrode 1 of the present embodiment facilitates construction of battery cells, cell stacks, and RF battery systems with excellent battery performance. Specifically, the electrode 1 of the present embodiment facilitates construction of battery cells, cell stacks, and RF battery systems with high current efficiency and low cell resistivity.
- the electrode manufacturing method of the present embodiment includes the following steps S1 and S2.
- step S1 a sheet-like first electrode material 11 is prepared.
- step S ⁇ b>2 the electrode 1 is produced by cutting the first electrode material 11 .
- step S2 has a step S21 and a step S22.
- a step S21 feeds the first electrode material 11 to the cutting tool 530 .
- step S22 the cutting tool 530 slices the first electrode material 11 so that the thickness of the first electrode material 11 is reduced. Steps S1 and S2 will be described in order below.
- the sheet-shaped first electrode material 11 to be prepared is composed of a nonwoven fabric containing a plurality of carbon fibers.
- the cross-sectional shape, density, etc. of the carbon fibers contained in the first electrode material 11 are the same as the cross-sectional shape, density, etc. of the carbon fibers contained in the electrode 1 described above.
- the first electrode material 11 is sliced so that the thickness of the first electrode material 11 is reduced in step S22, which will be described later.
- the electrode 1 is produced by slicing the first electrode material 11 . That is, the first electrode material 11 and the electrode 1 differ only in thickness.
- the planar shape, width Wb, and length Lb of the first electrode material 11 are maintained to the planar shape, width Wa, and length La of the electrode 1 .
- the width Wa and the length La of the electrode 1 can be adjusted.
- the planar shape, the numerical range of the width Wb, and the numerical range of the length Lb of the first electrode material 11 correspond to the planar shape of the sheet 2 constituting the electrode 1, the numerical range of the width Wa, and the numerical range of the length La. is similar to That is, the planar shape of the first electrode material 11 is rectangular.
- the width Wb of the first electrode material 11 is 1000 mm or less.
- the length Lb of the first electrode material 11 is 2000 mm or less.
- the first electrode material 11 By preparing the first electrode material 11 having a width Wb of 1000 mm or less and a length Lb of 2000 mm or less, it is easy to manufacture the electrode 1 with a small first variation in thickness.
- the second electrode 1 having a small variation in thickness is easily manufactured.
- the electrode 1 having a small first variation in basis weight is easily manufactured.
- the reason for this is that the width Wb of the first electrode material 11 is 1000 mm or less and the length Lb is 2000 mm or less, so that the first electrode material 11 extends along the width direction and the length direction of the first electrode material 11. This is because it is easy to cut at the same position in the thickness direction.
- the thickness of the first electrode material 11 is not particularly limited and can be appropriately selected as long as it is more than 1 times the average thickness of the electrode 1 to be produced.
- An example of the thickness of the first electrode material 11 is more than twice the average thickness of the electrode 1 , and an integer multiple of 3 times or more the average thickness of the electrode 1 .
- the thickness of the first electrode material 11 is an integer multiple of 20 or less times the average thickness of the electrode 1, further an integer multiple of 15 or less times, and particularly an integer multiple of 10 or less times. That is, the thickness of the first electrode material 11 is an integer multiple of 3 to 20 times the average thickness of the electrode 1, further an integer multiple of 4 to 15 times, particularly 5 to 10 times. It is an integral multiple of the following.
- the numerical ranges of the basis weight and the porosity of the first electrode material 11 are the same as the numerical ranges of the basis weight and the porosity of the sheet 2 described above.
- a cutting machine 500 is used for cutting the first electrode material 11 .
- the cutting machine 500 comprises a first roller 510 , a second roller 520 and a cutting tool 530 .
- the first roller 510 and the second roller 520 are feed rollers that feed the first electrode material 11 toward the cutting tool 530 .
- the first roller 510 and the second roller 520 are arranged vertically such that the peripheral surface of the first roller 510 and the peripheral surface of the second roller 520 face each other.
- the rotation axis of the first roller 510 and the rotation axis of the second roller 520 are parallel.
- the first roller 510 and the second roller 520 are drive rollers.
- a drive roller is a roller driven by a drive source such as a motor.
- the direction of rotation of the first roller 510 and the direction of rotation of the second roller 520 are opposite.
- the gap between the first roller 510 and the second roller 520 is a gap that satisfies the following requirement (a3) and requirement (b3).
- Requirement (a3) Pressure acts on the first electrode material 11 by sandwiching the first electrode material 11 from both sides in the thickness direction of the first electrode material 11 .
- Requirement (b3) By the friction between the first roller 510 and the first electrode material 11 accompanying the rotation of the first roller 510 and the friction between the second roller 520 and the first electrode material 11 accompanying the rotation of the second roller 520 , the first electrode material 11 moves from upstream to downstream of the first roller 510 and the second roller 520 .
- the cutting machine 500 of the present embodiment has a first roller 510 that can move at least one of the installation position of the first roller 510 and the installation position of the second roller 520 so as to increase or decrease the interval. It has a mechanism.
- the cutting machine 500 is provided with a first mechanism so that the first electrode material 11 with various thicknesses can be sent to the cutting tool 530 by rotating the first roller 510 and the second roller 520 .
- the width of the first roller 510 and the width of the second roller 520 are the same width.
- the width of the first roller 510 is the length along the axis of rotation of the first roller 510 .
- the width of the second roller 520 is the length along the axis of rotation of the second roller 520 .
- Width Wr of first roller 510 will be described representatively with reference to FIG.
- the width Wr of the first roller 510 is wider than the width Wb of the first electrode material 11 .
- An example of the width Wr of the first roller 510 is 1200 mm or less. If the width Wr of the first roller 510 is 1200 mm or less, the width Wr of the first roller 510 is not too wide. Therefore, the interval is easily maintained uniform along the width direction. That is, the pressure applied to the first electrode material 11 by the first roller 510 and the second roller 520 can be made uniform in the width direction of the first electrode material 11 . Therefore, it is possible to manufacture the electrode 1 with small variations in thickness.
- the cutting tool 530 is arranged downstream of the first roller 510 and the second roller 520 .
- the cutting tool 530 is provided parallel to the rotation axis of the first roller 510 .
- the cutting tool 530 is arranged so as to overlap the first roller 510 .
- the cutting tool 530 may be arranged away from the first roller 510 without overlapping the first roller 510.
- a knife can be used as the cutting tool 530 .
- the knife may be provided to travel in one direction along the rotation axis of the first roller 510, or may be provided to reciprocate along the direction parallel to the rotation axis of the first roller 510. good too.
- a ring-shaped band knife can be suitably used as the knife. This band knife runs in one direction in the longitudinal direction of the band knife.
- the cutting machine 500 of this embodiment includes a second mechanism capable of vertically moving the installation position of the cutting tool 530 .
- the installation position of the cutting tool 530 can be a position that satisfies the following requirement (a4) or requirement (b4).
- (a4) The thickness of the first electrode material 11 is evenly sliced.
- (b4) The thickness of the first electrode material 11 is sliced unevenly.
- the electrode 1 can be fabricated with the same thickness as For example, if the thickness of the first electrode material 11 is more than twice the average thickness of the electrode 1 and the installation position of the cutting tool 530 satisfies the above requirement (b4), as shown in FIG.
- the electrode 1 and the second electrode material 12 having an average thickness greater than that of the electrode 1 can be produced.
- the second electrode material 12 is sliced again as the first electrode material 11 .
- the installation position of the cutting tool 530 can be set to a position that satisfies the following requirement (a5) or requirement (b5) by controlling the second mechanism. can. (a5)
- the electrode 1 flows below the position where the cutting tool 530 is installed, and the second electrode material 12 flows above the position where the cutting tool 530 is installed.
- the electrode 1 flows above the position where the cutting tool 530 is installed, and the second electrode material 12 flows below the position where the cutting tool 530 is installed.
- the installation position of the cutting tool 530 that satisfies the requirement (a5) is more preferable than the position that satisfies the requirement (b5).
- the carbon fiber shavings generated by cutting are more likely to be between the first roller 510 and the first electrode material 11 than when the position satisfies the above requirement (b5). This is because clogging is less likely to occur between the second roller 520 and the first electrode material 11 .
- the cutting machine 500 may further include a table 540 shown in FIG. 8 and a pair of guides 550 shown in FIG. FIG. 6 omits the table and the pair of guides for convenience of explanation.
- FIG. 7 omits the table for convenience of explanation.
- FIG. 8 omits one guide for convenience of explanation.
- the table 540 is arranged upstream of the first roller 510 and the second roller 520 .
- the first electrode material 11 moves on the table 540 toward the first roller 510 and the second roller 520 .
- the table 540 includes a plurality of rollers.
- a plurality of rollers are arranged so that the rotation axes of the rollers are parallel to each other.
- the rotation axis of each roller is parallel to the rotation axis of the first roller 510 .
- a plurality of rollers are driven rollers.
- the driven roller is a roller that rotates due to friction with the first electrode material 11 but is not driven by a driving source such as a motor.
- the plurality of rollers may be drive rollers.
- a drive roller is a roller rotated by a drive source such as a motor. Since the table 540 has a plurality of rollers, the first electrode material 11 can easily move on the table 540 toward the first roller 510 and the second roller 520 .
- the pair of guides 550 regulates the displacement of the first electrode material 11 in the width direction.
- a pair of guides 550 can feed the first electrode material 11 straight toward the first roller 510 and the second roller 520 .
- Each of the pair of guides 550 is arranged on each side of the table 540 in the width direction.
- a ridge extending along the direction perpendicular to the width direction of the table 540 can be preferably used.
- a pair of guides 550 are arranged parallel to each other.
- a pair of guides 550 are arranged along a direction perpendicular to the rotation axis of the first roller 510 .
- the gap between the pair of guides 550 is slightly larger than the width Wb of the first electrode material 11 .
- Step S21 the first electrode material 11 is sandwiched between the first roller 510 and the second roller 520, and the first electrode material 11 is fed to the cutting tool 530 by rotating the first roller 510 and the second roller 520. be done.
- the first electrode material 11 is not pulled from the downstream side of the first roller 510 and the second roller 520 . That is, the first electrode material 11 is sent to the cutting tool 530 without substantially acting on the first electrode material 11 in tension along the traveling direction of the first electrode material 11 .
- substantially no tension is applied to the first electrode material 11 in the traveling direction of the first electrode material 11 .
- Step S22 In step S ⁇ b>22 , the first electrode material 11 is sliced without substantially acting on the first electrode material 11 with tension along the traveling direction of the first electrode material 11 . Therefore, the same position in the thickness direction of the first electrode material 11 is easily cut along the width direction and the length direction of the first electrode material 11 by the cutting tool 530 .
- the electrode 1 having an average thickness of 0.5 mm or more and 3 mm or less is preferably manufactured.
- the first electrode material 11 may be sliced so that the electrode 1 and the second electrode material 12 are produced by slicing the first electrode material 11 . Moreover, it is preferable to slice the first electrode material 11 so that the electrode 1 flows below the installation position of the cutting tool 530 and the second electrode material 12 flows above the installation position.
- the second electrode material 12 is sliced again by the cutting machine 500 as the first electrode material 11 . That is, step S21 and step S22 are repeated. Although it depends on the thickness of the first electrode material 11 to be prepared, two electrodes 1 are produced by slicing the second electrode material 12, and one electrode 1 is thicker than the electrode 1. In other cases, a single electrode 1 and a third electrode material thicker than the electrode 1 are produced. Steps S21 and S22 are repeated until two electrodes 1 or one electrode 1 and the remainder portion are fabricated by one step S2. That is, when the third electrode material is produced, the third electrode material is sliced again by the cutting machine 500 as the first electrode material 11 .
- the first step S22 to the last step before the final step. Up to S22, the first electrode material 11 is sliced unevenly. In the final step S22, the first electrode material 11 is evenly sliced.
- the electrode 1 produced by slicing the first electrode material 11 is a sheet 2 having a first surface 21 which is a cut surface and a second surface 22 which is a non-cut surface.
- the multiple carbon fibers forming the sheet 2 include the first carbon fibers described above and the multiple second carbon fibers described above.
- the first carbon fibers have cut surfaces facing the first surface 21 as described above.
- the first carbon fibers do not have a cut surface facing the second surface 22 .
- a plurality of cut surfaces of the first carbon fibers are arranged side by side on the first surface 21 .
- the second surface 22 faces the middle portion of the second carbon fiber in the longitudinal direction.
- the electrode 1 When one electrode 1 and one third electrode material are produced by slicing the second electrode material 12, the electrode 1 has a first surface 21 as a cut surface and a second surface 22 as a cut surface.
- one electrode 1 has a first surface 21 which is a cut surface and a non-cut surface.
- Another electrode 1 is a sheet 2 having a first surface 21 that is a cut surface and a second surface 22 that is a cut surface.
- the electrode manufacturing method of this embodiment can manufacture the electrode 1 described above.
- the width of the first electrode material 11 to be sliced is 1000 mm or less, and the length of the first electrode material 11 is 2000 mm or less. That is, the width of the first electrode material 11 is narrow and the length of the first electrode material 11 is short.
- the first electrode material 11 is sent to the cutting tool 530 by the rotation of the first roller 510 and the second roller 520 that sandwich the first electrode material 11 . That is, in the electrode manufacturing method of the present embodiment, the first electrode material 11 is sliced without substantially applying tension to the first electrode material 11 . Therefore, in the electrode manufacturing method of the present embodiment, it is easy to cut the same position in the thickness direction of the first electrode material 11 along the width direction and the length direction of the first electrode material 11 .
- the RF battery system 100 includes battery cells 4 .
- the battery cell 4 has a diaphragm 4M, a positive electrode 4P and a negative electrode 4N.
- the diaphragm 4M is arranged between the positive electrode 4P and the negative electrode 4N.
- At least one of the positive electrode 4P and the negative electrode 4N is composed of the electrode 1 described above.
- the RF battery system 100 shown in FIG. 9 charges and stores the power generated by the power generation unit 310 , discharges the stored power, and supplies it to the load 330 .
- RF battery system 100 is typically connected between power generation section 310 and load 330 via AC/DC converter 300 and transformer equipment 320 .
- An example of the power generation unit 310 is a solar power generation device, a wind power generation device, or other general power plants.
- An example of the load 330 is a power consumer or the like.
- a solid line arrow extending from the substation equipment 320 toward the AC/DC converter 300 means charging.
- a dashed arrow extending from the AC/DC converter 300 toward the substation 320 means discharge.
- the RF battery system 100 uses a positive electrolyte and a negative electrolyte.
- the positive electrode electrolyte and the negative electrode electrolyte contain, as active materials, metal ions whose valences change due to oxidation-reduction. Charging and discharging of the RF battery system 100 is performed using the difference between the oxidation-reduction potential of ions contained in the positive electrode electrolyte and the oxidation-reduction potential of ions contained in the negative electrode electrolyte. Examples of applications for the RF battery system 100 include load leveling, voltage sag compensation, emergency power, or output smoothing of natural energy sources such as solar or wind power.
- a battery cell 4 provided in the RF battery system 100 is separated into a positive electrode cell and a negative electrode cell by a diaphragm 4M.
- the diaphragm 4M is an ion exchange membrane that is impermeable to electrons but permeable to hydrogen ions, for example.
- the positive cell incorporates a positive electrode 4P.
- the negative cell incorporates a negative electrode 4N.
- An electrolytic solution is circulated in the battery cells 4 by a circulation mechanism 6, which will be described later.
- the circulation mechanism 6 includes a positive electrode circulation mechanism 6P and a negative electrode circulation mechanism 6N.
- the positive electrode circulation mechanism 6P circulates the positive electrode electrolyte to the positive electrode cells.
- the negative electrode circulation mechanism 6N circulates the negative electrode electrolyte to the negative electrode cells.
- Battery cells 4 are usually formed inside a structure called a cell stack 200 as shown in FIGS. 9 and 10 .
- the cell stack 200 includes a substack 201 , two end plates 220 and a tightening mechanism 230 .
- the cell stack 200 exemplifies a form including a plurality of sub-stacks 201 in the lower diagram of FIG. 10 .
- Each sub-stack 201 comprises a laminate and two feeding/discharging plates 210, as shown in the lower diagram of FIG.
- the laminate is constructed by stacking a plurality of cell frames 5, positive electrodes 4P, diaphragms 4M, and negative electrodes 4N in this order.
- the supply/discharge plates 210 are arranged at both ends of the laminate, as shown in the lower diagram of FIG.
- a supply pipe 63 and a discharge pipe 65 of the positive electrode circulation mechanism 6P and a supply pipe 64 and a discharge pipe 66 of the negative electrode circulation mechanism 6N, which will be described later, are connected to the supply/discharge plate 210 .
- the two end plates 220 sandwich the plurality of substacks 201 from the outside of the substacks 201 at both ends.
- a tightening mechanism 230 tightens both end plates 220 .
- the cell frame 5 includes bipolar plates 51 and a frame 52 .
- the frame 52 surrounds the outer peripheral edge of the bipolar plate 51 .
- One battery cell 4 is formed between the bipolar plates 51 of adjacent cell frames 5 .
- a positive electrode 4P is arranged on one side of the bipolar plate 51 so as to face each other.
- a negative electrode 4N is arranged on the other surface of the bipolar plate 51 so as to face each other.
- the frame body 52 is formed with liquid supply manifolds 53 and 54, liquid supply slits 53s and 54s, liquid discharge manifolds 55 and 56, and liquid discharge slits 55s and 56s, which will be described later.
- An annular seal member 57 is arranged in an annular seal groove between the frames 52 .
- the positive electrode circulation mechanism 6 ⁇ /b>P includes a positive electrode electrolyte tank 61 , a supply pipe 63 , a discharge pipe 65 and a pump 67 .
- a positive electrode electrolyte is stored in the positive electrode electrolyte tank 61 .
- the positive electrode electrolyte flows through the supply pipe 63 and the discharge pipe 65 .
- the supply pipe 63 connects the positive electrode electrolyte tank 61 and the positive electrode cell.
- the discharge pipe 65 connects the positive electrode cell and the positive electrode electrolyte tank 61 .
- the pump 67 pressure-feeds the positive electrode electrolyte in the positive electrode electrolyte tank 61 .
- the pump 67 is provided in the middle of the supply pipe 63 .
- the negative electrode circulation mechanism 6N includes a negative electrode electrolyte tank 62, a supply pipe 64, a discharge pipe 66, and a pump 68.
- a negative electrode electrolyte is stored in the negative electrode electrolyte tank 62 .
- a negative electrode electrolyte is circulated through the supply pipe 64 and the discharge pipe 66 .
- a supply pipe 64 connects the negative electrode electrolyte tank 62 and the negative electrode cell.
- the discharge pipe 66 connects the negative electrode cell and the negative electrode electrolyte tank 62 .
- a pump 68 pumps the negative electrode electrolyte in the negative electrode electrolyte tank 62 .
- a pump 68 is provided in the middle of the supply pipe 64 .
- the flow of the positive electrode electrolyte and the negative electrode electrolyte during charge/discharge operation is as follows.
- the positive electrode electrolyte is supplied from the positive electrode electrolyte tank 61 through the supply pipe 63 to the positive electrode cell by the pump 67 .
- the positive electrode electrolyte flows from the liquid supply manifold 53 through the liquid supply slit 53s and is supplied to the positive electrode 4P.
- the positive electrode electrolyte supplied to the positive electrode 4P flows from the lower side to the upper side of the positive electrode 4P as indicated by the arrows in the upper diagram of FIG.
- the positive electrode electrolyte that has flowed through the positive electrode 4 ⁇ /b>P flows through the drainage slit 55 s and is discharged to the drainage manifold 55 .
- the positive electrode electrolyte flows from the positive electrode cell through the discharge pipe 65 and is discharged to the positive electrode electrolyte tank 61 .
- a pump 68 supplies the negative electrode electrolyte from the negative electrode electrolyte tank 62 through the supply pipe 64 to the negative electrode cell.
- the negative electrode electrolyte flows from the liquid supply manifold 54 through the liquid supply slit 54s and is supplied to the negative electrode 4N.
- the negative electrode electrolyte supplied to the negative electrode 4N flows from the lower side to the upper side of the negative electrode 4N as indicated by the arrows in the upper diagram of FIG.
- the negative electrode electrolyte that has flowed through the negative electrode 4N flows through the drain slit 56s and is discharged to the drain manifold 56.
- the negative electrode electrolyte flows from the negative electrode cell through the discharge pipe 66 and is discharged to the negative electrode electrolyte tank 62 .
- the positive electrode electrolyte is circulated to the positive electrode cell, and the negative electrode electrolyte is circulated to the negative electrode cell.
- the pumps 67 and 68 are stopped during standby when charging and discharging are not performed. That is, the positive electrolyte and the negative electrolyte are not circulated.
- the positive electrode active material contained in the positive electrode electrolyte includes one or more selected from the group consisting of manganese ions, vanadium ions, iron ions, polyacids, quinone derivatives, and amines.
- the negative electrode active material contained in the negative electrode electrolyte includes one or more selected from the group consisting of titanium ions, vanadium ions, chromium ions, polyacids, quinone derivatives, and amines.
- RF battery system 100 may be, for example, an all-vanadium RF battery system in which each of the positive and negative electrode active materials is vanadium ions.
- Solvents for the positive electrode electrolyte and the negative electrode electrolyte include aqueous solutions containing one or more acids or acid salts selected from the group consisting of sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid.
- Sample no. 1 to sample no. 3 electrode similarly to the electrode manufacturing method of the above-described embodiment, the step S1 of preparing a sheet-like first electrode material and the step S2 of cutting the first electrode material to prepare an electrode are performed in this order. manufactured by
- the first electrode material of each sample consisted of a nonwoven fabric containing a plurality of carbon fibers.
- the plurality of carbon fibers includes carbon fibers having a plurality of pleats on their surfaces.
- the planar shape of each first electrode material is rectangular.
- the width and length of each first electrode material are as shown in Table 1.
- Step S2 In step S2, a step S21 of sending the first electrode material to the cutting tool and a step S22 of slicing the first electrode material so that the thickness of the first electrode material is reduced by the cutting tool were sequentially performed.
- step S2 the cutting machine 500 described above with reference to FIGS. 6 to 8 was used.
- the width of the first roller 510 and the width of the second roller 520 were greater than the width of each first electrode material.
- a knife was used as the cutting tool 530 .
- the installation position of the cutting tool 530 was a position that satisfies both the following requirement (a6) and requirement (b6).
- An electrode and a second electrode material having a thickness greater than the average thickness of the electrode are produced by slicing the first electrode material unevenly.
- the electrode flows below the position where the cutting tool 530 is installed, and the second electrode material flows above the position where the cutting tool 530 is installed.
- the average electrode thickness of each sample was varied.
- the spacing between the pair of guides 550 was slightly larger than the width of each first electrode material.
- each first electrode material was sent to the cutting tool 530 by rotating the first roller 510 and the second roller 520 that sandwich the first electrode material.
- step S22 an electrode and a second electrode material having a thickness greater than the average thickness of the electrode were produced. Further, in step S22, the produced electrode flowed below the position where the cutting tool 530 was installed, and the produced second electrode material flowed above the position where the cutting tool 530 was installed. In this example, the number of times that step S21 and step S22 were performed was five. That is, the number of electrodes produced from one first electrode material was six. Step S22 was performed so that the average thickness of the six electrodes was equal. The thickness of the first electrode material of each sample was such that the step S21 and step S22 were performed five times, and the average thickness of each electrode was the value shown in Table 2.
- Each electrode has a first surface and a second surface facing each other in the thickness direction.
- the first surface is the cut surface and the second surface is the non-cut surface.
- both the first surface and the second surface are cut surfaces.
- Each electrode was cut along the thickness direction of the electrode. The vicinity of the first surface in the cross section of each electrode was observed with an SEM.
- Each electrode was found to include a first carbon fiber having a cut surface facing the first face.
- the width and length of the electrode of each prepared sample were the same as the first electrode material of each prepared sample. Average thickness of electrode of each sample (mm), first variation in thickness (%), second variation in thickness (%), first variation in basis weight (%), second basis weight variation (g/m 2 ), basis weight (g/m 2 ), porosity (%), and density (g/cm 3 ) of the carbon fibers that make up the electrode of each sample were determined as described above. I asked. Those results are shown in Table 2. The results shown in Table 2 are the values for one of the six electrodes fabricated for each sample. Also, the tensile strength of the electrode of each sample is determined as described above.
- the tensile strength of the electrode of each sample satisfies the range of 40 kPa or more and 300 kPa or less. This tensile strength result is also the value for one of the six electrodes fabricated for each sample.
- Sample no. 101 electrode and sample no. 102 electrode is sample No. 1 to sample no. It was manufactured by a manufacturing method different from the manufacturing method of the electrode of No. 3. Sample no. 101 electrode and sample no. 102, the size of the electrode material to be prepared and the cutting method of the electrode material are the same as those of sample No. 102; 1 to sample no. 3 electrode manufacturing method. Sample no. 101 electrode and sample no. The electrode No. 102 was manufactured by sequentially performing a step S100 of preparing a roll-shaped electrode material and a step S200 of cutting the electrode material to prepare an electrode.
- the electrode material of each sample is composed of a nonwoven fabric containing a plurality of carbon fibers. Table 1 shows the width and length of each electrode material.
- step S200 the thickness of the electrode material is evenly sliced by a cutting tool.
- step S200 a first cutting machine different from the cutting machine 500 described above was used.
- the first cutting machine is equipped with a supply reel, an upper roller, a lower roller, a cutting tool and two take-up reels.
- a roll-shaped electrode material is installed on the supply reel.
- the supply reel is the driven reel.
- the upper roller and the lower roller are mainly not feed rollers for feeding the electrode material to the cutting tool, but guide rollers for regulating vertical displacement of the electrode material. That is, the upper and lower rollers are driven rollers rather than driven rollers.
- the width of the upper roller and the width of the lower roller were greater than the width of each electrode material.
- a knife was used as the cutting tool.
- the cutting tool was installed at a position where the thickness of the electrode material could be evenly sliced.
- Each take-up reel winds up each of the two long sheets produced.
- Each take-up reel is a drive reel.
- Each take-up reel winds up each of the two long sheets, thereby rewinding the electrode material set on the supply reel.
- the electrode material is sliced in a state in which tension is applied to the electrode material along the traveling direction of the electrode material by winding on each take-up reel.
- the number of times the step S200 was performed is a plurality of times.
- Each long sheet wound into a roll by each take-up reel is placed on the delivery reel, and sliced into a uniform thickness by the cutting tool as described above.
- the number of long sheets produced from one electrode material was four or more.
- the thickness of the electrode material of each sample was such that the average thickness of each long sheet was the value shown in Table 2 after performing step S200 a plurality of times.
- An electrode for each sample is obtained by cutting the long sheet of each sample into a predetermined length.
- the width and length of the long sheet of each sample prepared were the same as the electrode material of each prepared sample. Average thickness of long sheet of each sample (mm), first variation in thickness (%), second variation in thickness (%), first variation in basis weight (%), basis weight Second variation (g/m 2 ), basis weight (g/m 2 ), porosity (%), and carbon fiber density (g/cm 3 ) constituting the long sheet of each sample, Sample no. It was obtained in the same manner as for 1. Those results are shown in Table 2. The results shown in Table 2 are the values for one long sheet out of four or more long sheets produced.
- a single cell battery was produced using the electrode of each sample, and the current efficiency and cell resistivity were measured.
- a single cell battery is a battery having one positive electrode, one diaphragm, and one negative electrode.
- a single cell battery was constructed by stacking a first cell frame, a positive electrode, a diaphragm, a negative electrode, and a second cell frame in this order. The diaphragm is sandwiched between the positive electrode and the negative electrode.
- the first cell frame is arranged such that the bipolar plate provided in the first cell frame and the positive electrode are in contact with each other.
- the second cell frame is arranged such that the bipolar plate provided in the second cell frame and the negative electrode are in contact with each other.
- sample no. 1 was applied to the positive electrode and the negative electrode. 1 to sample no. 3, sample no. 101, and sample no. 102 individual electrodes were used. The width and length of the electrodes of each sample were the same.
- the long sheets of sample No. 101 and sample No. 102 were cut into sample No. 101 and sample No. 102.
- sample no. 2 sample no. 101 and sample No. 102 had a width of 350 mm and a length of 500 mm.
- a vanadium sulfate solution containing vanadium ions as an active material was used for each of the positive electrode electrolyte and the negative electrode electrolyte.
- the battery cell of each sample was charged and discharged at a constant current density of 90 mA/cm 2 .
- multiple cycles of charging and discharging were performed.
- charging was switched to discharging when a preset switching voltage was reached, and discharging was switched to charging when a preset switching voltage was reached.
- the switching voltage from charge to discharge was set to 1.62V.
- the switching voltage from discharging to charging was set to 1.0V.
- the current efficiency (%) and cell resistivity ( ⁇ cm 2 ) of each sample were determined. The current efficiency was the average value calculated by (total discharge time/total charge time) ⁇ 100 for each cycle.
- the cell resistivity was calculated by ⁇ (difference between average voltage during charge and average voltage during discharge)/(average current/2) ⁇ effective area of electrode.
- the effective area was 320 mm ⁇ 470 mm.
- the average voltage during charging and the average voltage during discharging were the average voltages in an arbitrary one cycle among a plurality of cycles. Those results are shown in Table 3.
- Each of the 3 electrodes was sample no. 101 and sample no. The first variation in thickness and the second variation in thickness were small compared to each of the 102 elongated sheets.
- Each of the 3 electrodes was sample no. 101 and sample no. The first variation in the basis weight and the second variation in the basis weight were smaller than each of the 102 long sheets.
- Each of the single cell batteries using No. 3 electrodes was sample no. 101 and sample no. Compared to each of the single cell batteries using the 102 long sheets, the current efficiency was high and the cell resistivity was low. From this result, sample no. 1 to sample no.
- Each of the 3 electrodes was sample no. 101 and sample no. It was found that a battery cell having excellent battery performance can be constructed compared to each of the 102 long sheets.
- sample No. Sample No. 101 was prepared in the same manner. 200 long sheets are produced. That is, the electrode material having a width of 1000 mm or less is evenly sliced in a state in which tension is applied along the traveling direction of the electrode material. Sample no. 200 long sheet thickness first variation (%), thickness second variation (%), basis weight first variation (%), and basis weight second variation (g/ m 2 ), sample no. It is obtained in the same manner as the long sheet of 101. As a result, sample no. The first variation in thickness, the second variation in thickness, the first variation in basis weight, and the second variation in basis weight of the long sheet of sample No. 200 were obtained.
- sample no. 200 single cell battery is sample no. 1 to sample no. It is considered that the battery performance is inferior to that of the single cell battery of No. 3.
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Abstract
Description
電池システムに用いられる電極であって、
複数の炭素繊維を含む不織布で構成されたシートを備え、
前記シートは、前記シートの厚さに沿った方向に互いに向かい合う第一面及び第二面を有し、
前記複数の炭素繊維は、第一炭素繊維を含み、
前記第一炭素繊維は、前記第一面に臨む切断面、及び前記第二面に臨む切断面の少なくとも一方の切断面を有し、
前記シートの幅が1000mm以下であり、
前記シートの長さが2000mm以下である。
電池システムに用いられる電極の製造方法であって、
1000mm以下の幅及び2000mm以下の長さを有すると共に、複数の炭素繊維を含む不織布で構成されているシート状の第一電極素材を準備する工程と、
前記第一電極素材を切断することで前記電極を作製する工程と、を備え、
前記電極を作製する工程は、
前記第一電極素材を挟む第一ローラー及び第二ローラーの回転によって前記第一電極素材を切断工具に送る工程と、
前記切断工具によって前記第一電極素材の厚さが薄くなるように前記第一電極素材をスライスする工程と、を有する。
上述した特許文献1の技術では、幅が広くかつ長さが長い炭素繊維不織布に張力が作用した状態で炭素繊維不織布が切断される。そのため、特許文献1の技術では、厚さのばらつきが小さい電極を作製できない。その理由は、次の通りである。
本開示の電極は、厚さのばらつきが小さい。
最初に本開示の実施態様を列記して説明する。
電池システムに用いられる電極であって、
複数の炭素繊維を含む不織布で構成されたシートを備え、
前記シートは、前記シートの厚さに沿った方向に互いに向かい合う第一面及び第二面を有し、
前記複数の炭素繊維は、第一炭素繊維を含み、
前記第一炭素繊維は、前記第一面に臨む切断面、及び前記第二面に臨む切断面の少なくとも一方の切断面を有し、
前記シートの幅が1000mm以下であり、
前記シートの長さが2000mm以下である。
前記シートの平均厚さが0.5mm以上3mm以下であるとよい。
前記シートの長さが500mm以上であるとよい。
前記シートの厚さのばらつきが25%以下であるとよい。
前記シートの目付量のばらつきが25%以下であるとよい。
前記シートの目付量が50g/m2以上350g/m2以下であるとよい。
前記複数の炭素繊維は、表面に複数のひだを有する炭素繊維を含むとよい。
前記複数の炭素繊維の密度が1.5g/cm3以上2.2g/cm3以下であり、
前記シートの空隙率が60%以上99%以下であるとよい。
上記(1)から上記(8)のいずれか1つに記載の電極を備える。
上記(9)に記載の電池セルを複数備える。
上記(9)に記載の電池セル、又は上記(10)に記載のセルスタックを備える。
電池システムに用いられる電極の製造方法であって、
1000mm以下の幅及び2000mm以下の長さを有すると共に、複数の炭素繊維を含む不織布で構成されているシート状の第一電極素材を準備する工程と、
前記第一電極素材を切断することで前記電極を作製する工程と、を備え、
前記電極を作製する工程は、
前記第一電極素材を挟む第一ローラー及び第二ローラーの回転によって前記第一電極素材を切断工具に送る工程と、
前記切断工具によって前記第一電極素材の厚さが薄くなるように前記第一電極素材をスライスする工程と、を有する。
前記第一電極素材をスライスする工程では、前記電極の平均厚さが0.5mm以上3mm以下となるように前記第一電極素材をスライスするとよい。
前記第一電極素材を準備する工程では、前記電極の平均厚さの2倍超の厚さを有する前記第一電極素材を準備し、
前記第一電極素材をスライスする工程では、前記電極と前記電極の平均厚さよりも厚さの厚い第二電極素材とが作製されるように前記第一電極素材をスライスするとよい。
前記第一電極素材を準備する工程では、前記電極の平均厚さの3倍以上の整数倍の厚さを有する前記第一電極素材を準備し、
前記第一電極素材をスライスする工程では、前記電極と前記電極の平均厚さよりも厚さの厚い第二電極素材とが作製されるように前記第一電極素材をスライスするとよい。
前記第一電極素材をスライスする工程では、前記電極が前記切断工具の設置位置よりも下方に流れ、前記第二電極素材が前記設置位置よりも上方に流れるように前記第一電極素材をスライスするとよい。
前記第一電極素材を前記切断工具に送る工程では、前記第一電極素材の幅方向へのずれをガイドによって規制しながら前記第一電極素材を前記切断工具に送るとよい。
本開示の実施形態の電極、電極の製造方法、及び電池システムの詳細を、以下に説明する。電池とは、レドックスフロー電池、燃料電池、リチウムイオン電池など、炭素材料を電極などに用いる電池をいう。以下の電池システムは、レドックスフロー電池システムを例に説明する。レドックスフロー電池システムをRF電池システムと表記することがある。図中の同一符号は同一名称物を示す。
〔電極〕
図1から図8を参照して、実施形態の電極1を説明する。電極1は、図9を参照して後述するRF電池システム100に用いられる。電極1は、複数の炭素繊維を含む不織布で構成されたシート2を備える。本形態の電極1の特徴の一つは、以下の要件(a1)及び要件(b1)を満たすことにある。
(a1)図1に示すように、シート2が特定の幅Waと特定の長さLaとを有する。
(b1)複数の炭素繊維が特定の第一炭素繊維を有する。
シート2は、炭素繊維を主成分として含む。炭素繊維を主成分とするとは、シート2の重量に対する炭素繊維の重量の比が50%以上であることをいう。シート2の重量に対する炭素繊維の重量の比は、更に60%以上であり、特に70%以上であるとよい。シート2は、複数の炭素繊維を含む不織布である。不織布は、独立した炭素繊維を交絡させたものである。複数の炭素繊維は、三次元の網目構造を構成する。炭素繊維同士の間、即ち網目の隙間には、空隙が設けられている。シート2は、バインダー、炭素粒子、触媒、親水性の材料、及び疎水性の材料の少なとも1つを含んでいてもよい。バインダーは、炭素繊維同士を決着する。炭素粒子は、シート2の表面積を大きくする。触媒は、電池反応を促進する。シート2は、図2に示すように、シート2の厚さに沿った方向に互いに向かい合う第一面21及び第二面22を有する。第一面21及び第二面22の少なくとも一方の面は切断面である。
シート2の平面形状は、図1に示すように、矩形状である。平面形状とは、第一面21又は第二面22をシート2の厚さ方向から見たときの形状である。ここでいう矩形状とは、長方形と正方形とが含まれる。シート2の平面形状が長方形である場合、シート2の短辺に対する長辺の比の一例は、1超5以下である。上記比は、更に1超3以下、特に1超2以下でもよい。
シート2の幅Waは、1000mm以下である。幅Waが1000mm以下であることで、シート2の厚さのばらつきは小さい。幅Waは、図7などを参照して後述する実施形態の電極の製造方法において準備する第一電極素材11の幅Wbが維持される。例えば、幅Waが1000mmであるシート2は、幅Wbが1000mmである第一電極素材11を用いて作製される。幅Wbが1000mm以下であることで、実施形態の電極の製造方法において、第一電極素材11の幅方向に沿って第一電極素材11の厚さ方向の同じ位置を切断し易い。よって、実施形態の電極の製造方法では、厚さのばらつきが小さいシート2が得られる。幅Waが小さいほど、シート2の厚さのばらつきは小さくなり易い。幅Waは、更に750mm以下であり、特に500mm以下である。幅Waの下限値の一例は、200mmである。幅Waが200mm以上なシート2は、高出力な電池セル、セルスタック、及びRF電池システムを構築し易い。幅Waは、200mm以上1000mm以下であり、更に300mm以上750mm以下であり、特に350mm以上500mm以下である。幅Waは、シート2の最大幅である。
シート2の長さLaは、2000mm以下である。長さLaが2000mm以下であることで、シート2の厚さのばらつきは小さい。長さLaは、図7に示す第一電極素材11の長さLbが維持される。例えば、長さLaが2000mmであるシート2は、長さLbが2000mmの第一電極素材11を用いて作製される。長さLbが2000mm以下であることで、実施形態の電極の製造方法において、第一電極素材11の長さ方向に沿って第一電極素材11の厚さ方向の同じ位置を切断し易い。よって、実施形態の電極の製造方法では、厚さのばらつきが小さいシート2が得られる。長さLaが小さいほど、シート2の厚さのばらつきは小さくなり易い。長さLaは、更に1500mm以下であり、特に1000mm以下である。長さLaの下限値の一例は、500mmである。長さLaが500mm以上であるシート2は、高出力な電池セル、セルスタック、及びRF電池システムを構築し易い。長さLaは、500mm以上2000mm以下であり、更に650mm以上1500mm以下であり、特に750mm以上1000mm以下である。長さLaは、500mm以上1000mm以下でもよい。長さLaは、シート2の最大長さである。
シート2の平均厚さの一例は、0.5mm以上3mm以下である。平均厚さが0.5mm以上であるシート2は、電池性能に優れる電池セル、セルスタック、及びRF電池システムを構築し易い。その上、平均厚さが0.5mm以上であるシート2は、機械的強度に優れる。平均厚さが3mm以下であるシート2は、薄型の電池セル、及びセルスタックを構築し易い。そのため、平均厚さが3mm以下であるシート2は、小型なRF電池システムを構築し易い。シート2の平均厚さの一例は、0.5mm以上2.5mm以下、更に0.6mm以上2.0mm以下であり、特に0.8mm以上1.5mm以下である。
第一交点P1は、第一仮想線V1と第三仮想線V3との交点である。
第二交点P2は、第一仮想線V1と第四仮想線V4との交点である。
第三交点P3は、第二仮想線V2と第三仮想線V3との交点である。
第四交点P4は、第二仮想線V2と第四仮想線V4との交点である。
図4では、第五交点P5は、第五仮想線V5と第三仮想線V3との交点である。
図5では、第五交点P5は、第一仮想線V1と第五仮想線V5との交点である。
図4では、第六交点P6は、第五仮想線V5と第四仮想線V4との交点である。
図5では、第六交点P6は、第二仮想線V2と第五仮想線V5との交点である。
第二仮想線V2は、シート2の幅方向に沿った直線であって、シート2の第二短辺から第二仮想線V2までの距離が長さLa×0.1倍以上長さLa×0.2倍以下となる直線である。
第一短辺から第一仮想線V1までの距離と第二短辺から第二仮想線V2までの距離とは同一とする。
第三仮想線V3は、シート2の長さ方向に沿った直線であって、シート2の第一長辺から第三仮想線V3までの距離が幅Wa×0.1倍以上幅Wa×0.2倍以下となる直線である。
第四仮想線V4は、シート2の長さ方向に沿った直線であって、シート2の第二長辺から第四仮想線V4までの距離が幅Wa×0.1倍以上幅Wa×0.2倍以下となる直線である。
第一長辺から第三仮想線V3までの距離と第二長辺から第四仮想線V4までの距離とは同一とする。
図4では、第五仮想線V5は、第一仮想線V1と第二仮想線V2との間を均等に分割する直線である。図5では、第五仮想線V5は、第三仮想線V3と第四仮想線V4との間を均等に分割する直線である。
(a2)第三仮想線V3上における第一交点P1と第三交点P3との間に複数の交点が等間隔に並び、第四仮想線V4上における第二交点P2と第四交点P4との間に複数の交点が等間隔に並ぶ。
(b2)第一仮想線V1上における第一交点P1と第二交点P2との間に複数の交点が等間隔に並び、第二仮想線V2上における第三交点P3と第四交点P4との間に複数の交点が等間隔に並ぶ。
上記要件(a2)を満たすには、第一仮想線V1と第二仮想線V2との間を均等に分割する2本以上の仮想線をとる。
上記要件(b2)を満たすには、第三仮想線V3と第四仮想線V4との間を均等に分割する2本以上の仮想線をとる。
シート2の厚さの第一のばらつきの一例は、25%以下である。厚さの第一のばらつきは、「(厚さの標準偏差/厚さの平均値)×100」によって求められる。厚さの標準偏差は、上述の各交点における測定値とシート2の平均厚さとに基づく値である。厚さの平均値とは、上述のシート2の平均厚さである。厚さの第一のばらつきが25%以下であれば、電極1の電池性能が電極1の全域にわたって均一になり易い。厚さの第一のばらつきは、小さいほど好ましい。厚さの第一のばらつきの下限値の一例は、実用上、2%である。厚さの第一のばらつきは、2%以上25%以下であり、更に5%以上20%以下であり、特に6%以上15%以下である。厚さの第一のばらつきは、2%以上15%以下でもよい。
シート2の目付量の第一のばらつきの一例は、25%以下である。目付量の第一のばらつきは、「(目付量の標準偏差/目付量の平均値)×100」によって求められる。目付量の標準偏差は、各測定片の目付量の測定値と目付量の平均値に基づく値である。目付量の平均値は、次のようにして求める。1枚のシート2から6個以上の測定片を切り抜く。各測定片は、上記各交点を中心とする正方形状とする。各測定片の1辺の長さは30mmとする。各測定片の目付量は、単位面積当たりの重量を測定して求める。求めた全ての目付量の平均値をとる。目付量の第一のばらつきが25%以下であれば、電極1の導電性及び電解液の流通性が電極1の全域にわたって均一になり易い。目付量の第一のばらつきは、小さいほど好ましい。目付量の第一のばらつきの下限値の一例は、実用上、2%である。目付量の第一のばらつきは、2%以上25%以下であり、更に5%以上20%以下であり、特に6%以上15%以下である。目付量の第一ばらつきは2%以上15%以下でもよい。
シート2の目付量の一例は、50g/m2以上350g/m2以下である。シート2の目付量とは、1枚のシート2全体の目付量である。目付量は、単位面積当たりの重量を測定して求める。目付量が50g/m2以上であるシート2は、炭素繊維同士の接点を多くし易いため、導電性を高め易い。目付量が350g/m2以下であるシート2は、空隙を確保し易いため、電解液の流通性に優れる。シート2の目付量は、更に70g/m2以上300g/m2以下、特に80g/m2以上250g/m2以下が挙げられる。
シート2の空隙率の一例は、60%以上99%以下である。シート2の空隙率が60%以上であれば、空隙率が60%未満のシートに比較して空隙が多い。このシート2は、電解液の流通性に優れる。シート2の空隙率が99%以下であれば、電極1は電池反応性に優れる。シート2の空隙率は、60%以上95%以下であり、更に65%以上94%以下であり、特に75%以上90%以下である。空隙率は、「100-[{目付量(g/m2)/平均厚さ(mm)/1000/密度(g/cm3)}×100]」によって求められる。密度は、炭素繊維の密度である。炭素繊維の密度は、後述する。
複数の炭素繊維は、図3に示すように、本形態では表面に複数のひだ35を有する炭素繊維30を含む。図3は、炭素繊維30の断面の輪郭を模式的に示している。炭素繊維30は、表面にひだ状の凹凸構造を有する。炭素繊維30の表面に複数のひだ35を有することで、炭素繊維30の表面積を大きくし易い。表面積が大きい炭素繊維30は、電解液と接する反応面積が増加し易い。よって、電極1と電解液との反応性が改善される。炭素繊維30の断面形状は、異形断面形状である。上述の第一炭素繊維及び上述の第二炭素繊維の少なくとも一方がひだ35を有していてもよい。複数の炭素繊維は、ひだ35を有していない炭素繊維を含んでいてもよい。また、複数の炭素繊維の全てがひだ35を有していなくてもよい。ひだ35を有していない炭素繊維の断面形状は、例えば、円形状、又は楕円形状などでもよい。
周長L1と周長L2との周長比L1/L2の一例は、1超である。周長L1は、炭素繊維30の断面の周長である。周長L2は、炭素繊維30の断面に外接する仮想矩形Rの周長である。
面積Saと面積Sbとの面積比Sa/Sbの一例は、0.5以上0.8以下である。面積Saは、炭素繊維30の断面の面積である。面積Sbは、炭素繊維30の断面に外接する仮想矩形Rの面積である。炭素繊維30の断面は、電極1の厚さ方向に沿って電極1を切断したときの断面である。
炭素繊維30の長径の一例は、5μm以上20μm以下である。炭素繊維30の長径は、仮想矩形Rの長辺の長さbに相当する。炭素繊維30の長径が5μm以上であることで、炭素繊維30の強度を確保し易く、電極1の強度低下が抑制される。炭素繊維30の長径が20μm以下であることで、炭素繊維30が細い。そのため、炭素繊維30は可とう性を有する。よって、炭素繊維30が図10の上図を参照して後述する隔膜4Mに突き刺さり難い。また、炭素繊維30の長径が20μm以下である場合、電極1の単位体積あたりの反応面積が増える。そのため、電極1と電解液との反応効率が高くなる。炭素繊維30の長径は、更に15μm以下である。炭素繊維30の短径は、長径と同等以下である。炭素繊維30の短径は、仮想矩形Rの短辺の長さaに相当する。炭素繊維30の短径の一例は、2μm以上15μm以下である。
炭素繊維の密度の一例は、1.5g/cm3以上2.2g/cm3以下である。炭素繊維の密度が1.5g/cm3以上であれば、導電成分が多い。この炭素繊維を含む電極1は、内部抵抗の小さい電池セルを構築し易い。炭素繊維の密度が2.2g/cm3以下であれば、炭素繊維の剛性が高過ぎない。この炭素繊維を含む電極1は、図10の上図を参照して後述する隔膜4Mが損傷し難い電池セルを構築し易い。炭素繊維の密度は、更に1.7g/cm3以上2.1g/cm3以下であり、特に1.8g/cm3以上2.0g/cm3以下である。炭素繊維の密度は、JIS R 7603:1999のA法:液置換法に準拠して測定することで求められる。
シート2の引張強度の一例は、40kPa以上300kPa以下である。引張強度が40kPa以上のシート2は、強度に優れる。引張強度が300kPa以下のシート2は、隔膜4Mの損傷を抑制し易い。シート2の引張強度は、更に60kPa以上200kPa以下であり、特に70kPa以上150kPa以下である。シート2の引張強度は、JIS L 1913:2010に準拠して測定することで求められる。
本形態の電極1は、厚さの第一のばらつき、厚さの第二のばらつき、目付量の第一のばらつき、及び目付量の第二のばらつきが小さいため、電池性能の局所的な低下が生じ難い。そのため、本形態の電極1は、電池性能に優れる電池セル、セルスタック、及びRF電池システムを構築し易い。具体的には、本形態の電極1は、電流効率が高く、かつセル抵抗率が小さい電池セル、セルスタック、及びRF電池システムを構築し易い。
図6から図8を参照して、実施形態の電極の製造方法を説明する。本形態の電極の製造方法は、以下の工程S1及び工程S2を備える。
工程S1は、シート状の第一電極素材11を準備する。
工程S2は、第一電極素材11を切断することで電極1を作製する。
工程S2は、工程S21と工程S22とを有する。
工程S21は、第一電極素材11を切断工具530に送る。
工程S22は、切断工具530によって第一電極素材11の厚さが薄くなるように第一電極素材11をスライスする。
以下、工程S1及び工程S2を順に説明する。
準備するシート状の第一電極素材11は、複数の炭素繊維を含む不織布で構成されている。第一電極素材11に含まれる炭素繊維の断面形状及び密度などは、上述した電極1に含まれる炭素繊維の断面形状及び密度などと同様である。第一電極素材11は、後述する工程S22において、第一電極素材11の厚さが薄くなるようにスライスされる。第一電極素材11がスライスされることによって電極1が作製される。即ち、第一電極素材11と電極1とは厚さが異なるだけである。第一電極素材11の平面形状、幅Wb、及び長さLbは、電極1の平面形状、幅Wa、及び長さLaに維持される。第一電極素材11の幅Wb及び長さLbを調整することで、電極1の幅Wa及び長さLaを調整できる。第一電極素材11の平面形状、幅Wbの数値範囲、及び長さLbの数値範囲は、上述した電極1を構成するシート2の平面形状、幅Waの数値範囲、及び長さLaの数値範囲と同様である。即ち、第一電極素材11の平面形状は矩形状である。第一電極素材11の幅Wbは、1000mm以下である。第一電極素材11の長さLbは、2000mm以下である。
第一電極素材11の切断には、切断機500を用いる。切断機500は、第一ローラー510と第二ローラー520と切断工具530とを備える。
要件(a3)第一電極素材11の厚さ方向の両側から第一電極素材11を挟むことで第一電極素材11に圧力が作用する。
要件(b3)第一ローラー510の回転に伴う第一ローラー510と第一電極素材11との摩擦と、第二ローラー520の回転に伴う第二ローラー520と第一電極素材11との摩擦とよって、第一ローラー510及び第二ローラー520の上流から下流に向かって第一電極素材11が移動する。
(a4)第一電極素材11の厚さが均等にスライスされる。
(b4)第一電極素材11の厚さが不均等にスライスされる。
例えば、第一電極素材11の厚さが電極1の平均厚さの2倍であり、切断工具530の設置位置が上記要件(a4)を満たす位置であれば、図示は省略するものの、2枚の同じ厚さの電極1を作製することができる。
例えば、第一電極素材11の厚さが電極1の平均厚さの2倍超であり、切断工具530の設置位置が上記要件(b4)を満たす位置であれば、図6に示すように、電極1と電極1よりも平均厚さの厚い第二電極素材12とを作製することができる。第二電極素材12は第一電極素材11として再度スライスされる。
(a5)電極1が切断工具530の設置位置よりも下方に流れ、第二電極素材12が切断工具530の設置位置よりも上方に流れる。
(b5)電極1が切断工具530の設置位置よりも上方に流れ、第二電極素材12が切断工具530の設置位置よりも下方に流れる。
切断工具530の設置位置は上記要件(a5)を満たす位置とする場合は、上記要件(b5)を満たす位置とする場合よりも好ましい。上記要件(a5)を満たす位置とする場合は、上記要件(b5)を満たす位置とする場合よりも、切断によって生じる炭素繊維の切り屑が第一ローラー510と第一電極素材11との間、第二ローラー520と第一電極素材11との間に詰まり難いからである。
工程S21では、第一ローラー510と第二ローラー520とによって第一電極素材11が挟まれ、第一ローラー510と第二ローラー520とが回転することによって第一電極素材11が切断工具530に送られる。第一電極素材11は、第一ローラー510及び第二ローラー520の下流側から引っ張られていない。即ち、第一電極素材11の進行方向に沿った張力が第一電極素材11に実質的に作用されることなく、第一電極素材11が切断工具530に送られる。このように、本形態の電極の製造方法では、第一電極素材11に対して第一電極素材11の進行方向に張力が実質的に作用されない。
工程S22では、第一電極素材11の進行方向に沿った張力が第一電極素材11に実質的に作用されることなく第一電極素材11がスライスされる。そのため、切断工具530によって第一電極素材11の幅方向及び長さ方向に沿って第一電極素材11の厚さ方向の同じ位置が切断され易い。工程S22では、平均厚さが0.5mm以上3mm以下を満たす電極1を作製するとよい。工程S22では、第一電極素材11のスライスによって、電極1と第二電極素材12とが作製されるように第一電極素材11をスライスするとよい。その上、電極1が切断工具530の設置位置よりも下方に流れ、第二電極素材12が設置位置よりも上方に流れるように第一電極素材11をスライスするとよい。
本形態の電極の製造方法は、上述した電極1を製造できる。本形態の電極の製造方法では、スライスされる第一電極素材11の幅が1000mm以下であり、第一電極素材11の長さが2000mm以下である。即ち、第一電極素材11の幅が狭くかつ第一電極素材11の長さが短い。その上、本形態の電極の製造方法では、第一電極素材11を挟む第一ローラー510及び第二ローラー520の回転によって第一電極素材11が切断工具530に送られる。即ち、本形態の電極の製造方法では、第一電極素材11に張力が実質的に作用することなく第一電極素材11がスライスされる。よって、本形態の電極の製造方法は、第一電極素材11の幅方向及び長さ方向に沿って第一電極素材11の厚さ方向の同じ位置を切断し易い。
図9及び図10を参照して、実施形態のRF電池システム100を説明する。RF電池システム100は、電池セル4を備える。電池セル4は、隔膜4Mと正極電極4Pと負極電極4Nとを有する。隔膜4Mは、正極電極4Pと負極電極4Nとの間に配置されている。正極電極4P及び負極電極4Nの少なくとも一方は、上述した電極1で構成されている。
RF電池システム100に備わる電池セル4は、隔膜4Mによって正極セルと負極セルとに分離されている。隔膜4Mは、電子を透過しないが、例えば水素イオンを透過するイオン交換膜である。正極セルには、正極電極4Pが内蔵されている。負極セルには、負極電極4Nが内蔵されている。電池セル4には、後述する循環機構6によって電解液が循環される。循環機構6は、正極循環機構6Pと負極循環機構6Nとを備える。正極循環機構6Pは、正極セルに正極電解液を循環させる。負極循環機構6Nは、負極セルに負極電解液を循環させる。
電池セル4は、通常、図9と図10の下図とに示すように、セルスタック200と呼ばれる構造体の内部に形成される。セルスタック200は、サブスタック201と、2枚のエンドプレート220と、締付機構230とを備える。セルスタック200は、図10の下図では、複数のサブスタック201を備える形態を例示している。各サブスタック201は、図10の下図に示すように、積層体と、2枚の給排板210とを備える。積層体は、図9と図10の上図とに示すように、セルフレーム5、正極電極4P、隔膜4M、及び負極電極4Nを、この順番で複数積層して構成されている。給排板210は、図10の下図に示すように、積層体の両端に配置される。給排板210には、後述する正極循環機構6Pの供給管63と排出管65、及び負極循環機構6Nの供給管64と排出管66が接続される。2枚のエンドプレート220は、複数のサブスタック201を両端のサブスタック201の外側から挟み込む。締付機構230は、両エンドプレート220を締め付ける。
セルフレーム5は、双極板51と枠体52とを備える。枠体52は、双極板51の外周縁部を囲んでいる。隣接するセルフレーム5の双極板51の間に一つの電池セル4が形成される。双極板51の一方の面には、正極電極4Pが向かい合うように配置されている。双極板51の他方の面には、負極電極4Nが向かい合うように配置されている。枠体52には、後述する給液マニホールド53、54、給液スリット53s、54s、排液マニホールド55、56、及び排液スリット55s、56sが形成されている。各枠体52間には、環状のシール溝に環状のシール部材57が配置されている。
正極循環機構6Pは、正極電解液タンク61と、供給管63と、排出管65と、ポンプ67とを備える。正極電解液タンク61には、正極電解液が貯留される。供給管63と排出管65とは、正極電解液が流通される。供給管63は、正極電解液タンク61と正極セルとを接続している。排出管65は、正極セルと正極電解液タンク61とを接続している。ポンプ67は、正極電解液タンク61内の正極電解液を圧送する。ポンプ67は、供給管63の途中に設けられている。
正極電解液に含まれる正極活物質は、マンガンイオン、バナジウムイオン、鉄イオン、ポリ酸、キノン誘導体、及びアミンからなる群より選択される1種以上が挙げられる。負極電解液に含まれる負極活物質は、チタンイオン、バナジウムイオン、クロムイオン、ポリ酸、キノン誘導体、及びアミンからなる群より選択される1種以上が挙げられる。RF電池システム100は、例えば、正極活物質及び負極活物質の各々がバナジウムイオンである全バナジウムRF電池システムでもよい。正極電解液がマンガンイオンを含み、負極電解液がチタンイオンを含むと、高い起電力を有するRF電池システム100とし易い。正極電解液及び負極電解液の溶媒は、硫酸、リン酸、硝酸、塩酸からなる群より選択される1種以上の酸又は酸塩を含む水溶液などが挙げられる。
本形態のRF電池システム100は、正極電極4P及び負極電極4Nの少なくとも一方が電極1を備えるため、電流効率を高め易く、かつセル抵抗率を小さくし易い。
電極の製造方法の違いによる電池セルの電流効率及びセル抵抗率の違いを調べた。
試料No.1から試料No.3の電極は、上述した実施形態の電極の製造方法と同様、シート状の第一電極素材を準備する工程S1と、第一電極素材を切断することで電極を作製する工程S2とを順に行って製造した。
各試料の第一電極素材は、複数の炭素繊維を含む不織布で構成されている。複数の炭素繊維は、表面に複数のひだを有する炭素繊維を含む。各第一電極素材の平面形状は、長方形状である。各第一電極素材の幅、及び長さは、表1に示す通りである。
工程S2では、第一電極素材を切断工具に送る工程S21と、切断工具によって第一電極素材の厚さが薄くなるようにスライスする工程S22とを順に行った。
(a6)第一電極素材を不均等にスライスすることによって、電極と電極の平均厚さよりも厚さの厚い第二電極素材とが作製される。
(b6)電極が切断工具530の設置位置よりも下方に流れ、第二電極素材が切断工具530の設置位置よりも上方に流れる。
切断工具530の設置位置に対して第一ローラー510の設置位置及び第二ローラー520の設置位置の少なくとも一方を調整することで、各試料の電極の平均厚さを異ならせた。一対のガイド550同士の間の間隔は、各第一電極素材の幅よりも少し大きかった。
試料No.101の電極及び試料No.102の電極は、試料No.1から試料No.3の電極の製造方法とは異なる製造方法によって製造した。試料No.101の電極及び試料No.102の電極の製造方法は、準備する電極素材のサイズと電極素材の切断方法とが試料No.1から試料No.3の電極の製造方法と相違する。試料No.101の電極と試料No.102の電極とは、ロール状の電極素材を準備する工程S100と、電極素材を切断することで電極を作製する工程S200とを順に行って製造した。
各試料の電極素材は、複数の炭素繊維を含む不織布で構成されている。各電極素材の幅、及び長さは、表1に示す通りである。
工程S200では、切断工具によって電極素材の厚さを均等にスライスする。工程S200では、上述した切断機500とは異なる第一切断機を用いた。
各試料の電極を用いて単セル電池を作製し、電流効率及びセル抵抗率を測定した。単セル電池は、正極電極、隔膜、及び負極電極の数が1つずつの電池である。単セル電池は、第一セルフレーム、正極電極、隔膜、負極電極、及び第二セルフレームをこの順番で積層して構成した。隔膜は、正極電極と負極電極とで挟まれている。第一セルフレームに備わる双極板と正極電極とが接するように、第一セルフレームが配置されている。第二セルフレームに備わる双極板と負極電極とが接するように、第二セルフレームが配置されている。正極電極と負極電極とに、試料No.1から試料No.3、試料No.101、及び試料No.102の各々の電極を用いた。各試料の電極の幅及び長さは、互いに同一にした。ここでは、試料No.1及び試料No.2の電極、試料No.101及び試料No102の長尺シートをカットして、試料No.1、試料No.2、試料No.101、及び試料No102の電極の幅を350mmとし、長さを500mmとした。正極電解液及び負極電解液の各々は、活物質にバナジウムイオンを含む硫酸バナジウム溶液を用いた。
充放電後、各試料の電流効率(%)、及びセル抵抗率(Ω・cm2)を求めた。
電流効率は、サイクルごとに(放電時間の合計/充電時間の合計)×100により算出したものを平均した値とした。
セル抵抗率は、{(充電時の平均電圧と放電時の平均電圧との差)/(平均電流/2)}×電極の有効面積、により算出したものとした。有効面積は、320mm×470mmとした。充電時の平均電圧及び放電時の平均電圧は、複数サイクルのうち、任意の1サイクルにおける平均電圧とした。
それらの結果を表3に示す。
1 電極
2 シート
21 第一面、22 第二面
30 炭素繊維、35 ひだ
4 電池セル、4M 隔膜、4P 正極電極、4N 負極電極
5 セルフレーム、51 双極板、52 枠体
53、54 給液マニホールド、53s、54s 給液スリット
55、56 排液マニホールド、55s、56s 排液スリット
57 シール部材
6 循環機構、6P 正極循環機構、6N 負極循環機構
61 正極電解液タンク、62 負極電解液タンク
63、64 供給管、65、66 排出管、67、68 ポンプ
200 セルスタック、201 サブスタック
210 給排板、220 エンドプレート、230 締付機構
300 交流/直流変換器、310 発電部
320 変電設備、330 負荷
500 切断機
510 第一ローラー、520 第二ローラー
530 切断工具、540 テーブル、550 ガイド
11 第一電極素材、12 第二電極素材
Wa、Wb、Wr 幅、La、Lb、a、b 長さ
P1 第一交点、P2 第二交点、P3 第三交点
P4 第四交点、P5 第五交点、P6 第六交点
V1 第一仮想線、V2 第二仮想線、V3 第三仮想線
V4 第四仮想線、V5 第五仮想線
R 仮想矩形
Claims (17)
- 電池システムに用いられる電極であって、
複数の炭素繊維を含む不織布で構成されたシートを備え、
前記シートは、前記シートの厚さに沿った方向に互いに向かい合う第一面及び第二面を有し、
前記複数の炭素繊維は、第一炭素繊維を含み、
前記第一炭素繊維は、前記第一面に臨む切断面、及び前記第二面に臨む切断面の少なくとも一方の切断面を有し、
前記シートの幅が1000mm以下であり、
前記シートの長さが2000mm以下である、
電極。 - 前記シートの平均厚さが0.5mm以上3mm以下である、請求項1に記載の電極。
- 前記シートの長さが500mm以上である、請求項1又は請求項2に記載の電極。
- 前記シートの厚さのばらつきが25%以下である、請求項1から請求項3のいずれか1項に記載の電極。
- 前記シートの目付量のばらつきが25%以下である、請求項1から請求項4のいずれか1項に記載の電極。
- 前記シートの目付量が50g/m2以上350g/m2以下である、請求項1から請求項5のいずれか1項に記載の電極。
- 前記複数の炭素繊維は、表面に複数のひだを有する炭素繊維を含む、請求項1から請求項6のいずれか1項に記載の電極。
- 前記複数の炭素繊維の密度が1.5g/cm3以上2.2g/cm3以下であり、
前記シートの空隙率が60%以上99%以下である、請求項1から請求項7のいずれか1項に記載の電極。 - 請求項1から請求項8のいずれか1項に記載の電極を備える、
電池セル。 - 請求項9に記載の電池セルを複数備える、
セルスタック。 - 請求項9に記載の電池セル、又は請求項10に記載のセルスタックを備える、
電池システム。 - 電池システムに用いられる電極の製造方法であって、
1000mm以下の幅及び2000mm以下の長さを有すると共に、複数の炭素繊維を含む不織布で構成されているシート状の第一電極素材を準備する工程と、
前記第一電極素材を切断することで前記電極を作製する工程と、を備え、
前記電極を作製する工程は、
前記第一電極素材を挟む第一ローラー及び第二ローラーの回転によって前記第一電極素材を切断工具に送る工程と、
前記切断工具によって前記第一電極素材の厚さが薄くなるように前記第一電極素材をスライスする工程と、を有する、
電極の製造方法。 - 前記第一電極素材をスライスする工程では、前記電極の平均厚さが0.5mm以上3mm以下となるように前記第一電極素材をスライスする、請求項12に記載の電極の製造方法。
- 前記第一電極素材を準備する工程では、前記電極の平均厚さの2倍超の厚さを有する前記第一電極素材を準備し、
前記第一電極素材をスライスする工程では、前記電極と前記電極の平均厚さよりも厚さの厚い第二電極素材とが作製されるように前記第一電極素材をスライスする、請求項12又は請求項13に記載の電極の製造方法。 - 前記第一電極素材を準備する工程では、前記電極の平均厚さの3倍以上の整数倍の厚さを有する前記第一電極素材を準備し、
前記第一電極素材をスライスする工程では、前記電極と前記電極の平均厚さよりも厚さの厚い第二電極素材とが作製されるように前記第一電極素材をスライスする、請求項12から請求項14のいずれか1項に記載の電極の製造方法。 - 前記第一電極素材をスライスする工程では、前記電極が前記切断工具の設置位置よりも下方に流れ、前記第二電極素材が前記設置位置よりも上方に流れるように前記第一電極素材をスライスする、請求項14又は請求項15に記載の電極の製造方法。
- 前記第一電極素材を前記切断工具に送る工程では、前記第一電極素材の幅方向へのずれをガイドによって規制しながら前記第一電極素材を前記切断工具に送る、請求項12から請求項16のいずれか1項に記載の電極の製造方法。
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JPH0992321A (ja) * | 1995-09-27 | 1997-04-04 | Kashimakita Kyodo Hatsuden Kk | レドックス電池 |
JP2002537137A (ja) * | 1999-02-22 | 2002-11-05 | ザ、プロクター、エンド、ギャンブル、カンパニー | 材料ブロックから連続ウェブを製造するための方法及び装置 |
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