JP2022176621A - Method for inspecting battery sheet, method for manufacturing battery sheet, and method for manufacturing battery pack - Google Patents

Abstract

To provide a method for inspecting a battery sheet that can easily discover a short-circuit malfunction.SOLUTION: A method for inspecting a battery sheet includes: a measurement step of using a non-contact voltage measuring machine, with a battery sheet having a positive electrode resin collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode resin collector, which are laminated in order in a lamination direction as an object of inspection, thereby measuring voltage at a plurality of places on a surface of the battery sheet while separated from the surface of the battery sheet; and a determination step of determining whether a short-circuit place is present on the battery sheet based on the voltage.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for inspecting a battery sheet, a method for manufacturing a battery sheet, and a method for manufacturing an assembled battery.

As the demand for large-capacity batteries increases and many assembled batteries in which a plurality of single cells are stacked are manufactured, there is an increasing need to efficiently remove defective products in the manufacturing process.

Patent Document 1 discloses a battery short-circuit inspection method in which an electrode plate group formed by laminating a positive electrode plate and a negative electrode plate with a separator interposed therebetween is inserted into a battery case. A battery short-circuit inspection method is disclosed in which short-circuit defects are inspected while applying pressure to the electrode plate group before the assembly.

Patent Document 2 discloses a method for inspecting a unit cell that constitutes an assembled battery, wherein a plurality of unit cells are arranged in a stack, and each unit cell is inspected in a state in which the arrayed unit cell group is pressed in the stacking direction. A method for inspecting a unit cell is disclosed.

JP-A-2001-236985 JP 2005-339925 A

However, in the inspection method described in Patent Literature 1, short circuit defects are inspected in a state in which pressure is applied to the electrode plate group in which the unit cells are assembled. It is not easy to identify what is happening.

On the other hand, in the inspection method described in Patent Document 2, each unit cell is inspected while the unit cell group arranged in a stack is pressed in the stacking direction, so if a defect is found in the unit cell group, a defect occurs. It is necessary to replace the battery that is in the battery pack.

As described above, the conventional inspection method is not a method for efficiently discovering defects in units of cells, more specifically, in units of battery sheets used for cells.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for inspecting a battery sheet that can easily detect a short-circuit problem. Another object of the present invention is to provide a method for manufacturing a battery sheet using the method for inspecting a battery sheet. A further object of the present invention is to provide a method for manufacturing an assembled battery using the method for inspecting a battery sheet.

In the present invention, a battery sheet having a positive electrode resin current collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode resin current collector, which are laminated in order in the stacking direction, is used as a test object for non-contact voltage measurement. a measuring step of measuring voltages at a plurality of locations on the surface of the battery sheet in a state separated from the surface of the battery sheet by using a device; A battery sheet inspection method, comprising: a determination step of determining whether or not the battery sheet inspection method determines whether or not the battery sheet does not have the short-circuited portion; A method for manufacturing a battery sheet, comprising: a stacking step of stacking a plurality of battery sheets determined by the battery sheet inspection method to have no short-circuited portions. A method for manufacturing a battery.

ADVANTAGE OF THE INVENTION According to this invention, the malfunction of a short circuit can be easily discovered by a battery sheet unit. Furthermore, according to the present invention, since the non-contact voltage measuring device is in a completely non-contact state with the battery sheet, damage to the battery sheet may occur due to contact with the non-contact voltage measuring device during voltage measurement. In addition, foreign matter derived from the damage does not enter the battery sheet. Therefore, since it becomes easy to increase the voltage measurement speed and the voltage measurement frequency, the manufacturing efficiency of the battery sheet can be improved. As a result, it is possible to manufacture the assembled battery using battery sheets free from defects, so that the production yield of the assembled battery can be improved.

FIG. 1 is a schematic side view showing an example of the battery sheet inspection method of the present invention. FIG. 2 is a partially cutaway schematic perspective view showing an example of a battery sheet used as an inspection object in the battery sheet inspection method of the present invention. FIG. 3 is a partially cutaway schematic perspective view showing an example of an assembled battery.

[Battery sheet inspection method]
In the battery sheet inspection method of the present invention, a battery sheet having a positive electrode resin current collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode resin current collector stacked in order in the stacking direction is used as an inspection object. , by using a non-contact voltage measuring device, a measurement step of measuring the voltage at multiple locations on the surface of the battery sheet in a state separated from the surface of the battery sheet, and based on the voltage, there is a short-circuit location on the battery sheet. and a determination step of determining whether to

If the battery sheet, which is the object to be inspected, has a short circuit, the voltage at the short circuit is 0V. Therefore, when the voltage at the short-circuited portion is pinpoint-measured using a non-contact voltage measuring device, for example, the voltage at that portion is 0 V, even though the voltage at the other portion is about 100 mV. On the other hand, depending on the size of the non-contact voltage measuring instrument, there are cases where the voltages of the short-circuited portion and the surrounding non-short-circuited portions are measured together. In this case, the voltage to be measured is not 0V because the value includes not only the short-circuited portion but also the non-short-circuited portion, and is, for example, about 50 mV. In view of such behavior, in the method for inspecting a battery sheet of the present invention, when a portion where the measured voltage is outside the allowable range exists in the battery sheet, it is determined that the battery sheet has a short-circuit portion.

In the battery sheet inspection method of the present invention, the allowable voltage range is preferably ±30% of a predetermined value that depends on the specifications of the electrodes. The predetermined value can also be obtained from the average value of voltages measured at a plurality of points on the surface of the battery sheet, which is the object to be inspected.

As described above, in the method for inspecting a battery sheet of the present invention, it is possible to easily find a short-circuit problem for each battery sheet.

In the battery sheet inspection method of the present invention, a battery sheet having a positive electrode resin current collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode resin current collector stacked in order in the stacking direction is used as an inspection object. do. On the other hand, in a battery sheet having a conventional metal current collector, the electrical resistance in the lateral direction (plane direction) is low, and the current is uniform within the plane. Therefore, when a battery sheet having a metal current collector is to be inspected, even the method for inspecting a battery sheet according to the present invention cannot detect short-circuit defects. Thus, it can be said that the battery sheet inspection method of the present invention is effective only for battery sheets having resin current collectors.

In the battery sheet inspection method of the present invention, the battery sheet used as an inspection object is synonymous with a cell. Battery sheets, that is, cells, include, for example, lithium ion batteries. In this specification, the concept of lithium ion battery includes lithium ion secondary battery.

In the battery sheet inspection method of the present invention, in the measuring step, voltages are measured at a plurality of locations on the surface of the battery sheet in a state separated from the surface of the battery sheet by using a non-contact voltage measuring device. Thus, in the battery sheet inspection method of the present invention, the non-contact voltage measuring device is in a completely non-contact state with the battery sheet. , and foreign matter resulting from the damage does not enter the battery sheet. Therefore, in the battery sheet inspection method of the present invention, it becomes easy to increase the voltage measurement speed and the voltage measurement frequency, so that the manufacturing efficiency of the battery sheet can be improved.

Examples of non-contact voltage measuring instruments include non-contact AC voltage sensors manufactured by Iida Denshi Co., Ltd., "Clamp-on Power Logger PW3365-10" manufactured by Hioki Electric Co., Ltd., and "Fluke T6-1000" manufactured by Fluke Corporation. It is However, these non-contact voltage measuring instruments measure the voltage without contacting the metal part of the object to be measured. The voltage is measured while in contact with the In other words, these non-contact voltage measuring instruments do not measure the voltage in a completely non-contact state with the object to be measured.

It is possible to measure the voltage at multiple points on the surface of the battery sheet by using the non-contact voltage measuring device. However, the above non-contact voltage measuring device cannot measure voltages at a plurality of locations on the surface of the battery sheet while being separated from the surface of the battery sheet, that is, in a completely non-contact state with the battery sheet.

In the battery sheet inspection method of the present invention, the method of directing the non-contact voltage measuring device to the surface of the battery sheet is not particularly limited. The following method is preferred as shown in FIG.

In the battery sheet inspection method of the present invention, in the measuring step, the non-contact voltage measuring device is arranged so as to face the stacking direction while being separated from a portion of the surface of the battery sheet facing the stacking direction. is preferred.

In the battery sheet inspection method of the present invention, in the measuring step, the battery sheet is preferably passed through a region in which the non-contact voltage measuring devices are arranged facing each other in the stacking direction.

In the battery sheet inspection method of the present invention, a conveying mechanism may be used as means for moving the battery sheet, or other means (for example, manual pulling) may be used.

In the battery sheet inspection method of the present invention, the non-contact voltage measuring device may be moved instead of moving the battery sheet. Also, both the battery sheet and the non-contact voltage measuring device may be moved.

FIG. 1 is a schematic side view showing an example of the battery sheet inspection method of the present invention.

In FIG. 1, the non-contact voltage measuring device 2 is arranged so as to face the stacking direction T while being separated from a portion of the surface of the battery sheet (single cell) 1 facing the stacking direction T. . By passing the battery sheet 1 in the length direction L using a conveying mechanism or the like in the region where the non-contact voltage measuring device 2 is arranged facing the stacking direction T in this way, the non-contact voltage Using the measuring device 2, the voltage at a plurality of locations in the length direction L of the surface of the battery sheet 1 can be continuously measured (monitored).

The dimension in the length direction L of the non-contact voltage measuring device 2, more specifically, the dimension in the length direction L of the portion of the non-contact voltage measuring device 2 facing the surface of the battery sheet 1 is the battery Compared to the dimension in the length direction L of the sheet 1, it may be smaller, the same, or larger.

The dimension in the width direction W of the non-contact voltage measuring device 2, more specifically, the dimension in the width direction W of the portion of the non-contact voltage measuring device 2 facing the surface of the battery sheet 1 may be smaller, the same, or larger than the dimension in the width direction W of .

When the non-contact voltage measuring device 2 has a form that spreads in the width direction W, the battery sheet is placed in the region where the non-contact voltage measuring device 2 is arranged facing the stacking direction T using a conveying mechanism or the like. 1 in the length direction L, while simultaneously measuring the voltage at multiple locations in the width direction W on the surface of the battery sheet 1 using the non-contact voltage measuring device 2, the surface of the battery sheet 1 Voltages at multiple locations in the length direction L can be measured continuously.

On both sides of the battery sheet 1, a non-contact voltage measuring device may be further arranged at a position separated in the length direction L, apart from the non-contact voltage measuring device 2 shown in FIG.

A plurality of pairs of non-contact voltage measuring devices 2 may be arranged along the width direction W on both sides of the battery sheet 1 . More specifically, a plurality of pairs of non-contact voltage measuring devices 2 are arranged so as to face the stacking direction T while being separated from a portion of the surface of the battery sheet 1 facing the stacking direction T. good too. In this state, by moving the battery sheet 1 in the length direction L, while simultaneously measuring the voltage at a plurality of locations in the width direction W on the surface of the battery sheet 1, can continuously measure the voltage at multiple points.

On both sides of the battery sheet 1, apart from the plurality of pairs of non-contact voltage measuring devices 2 described above, at positions separated in the length direction L, a plurality of pairs of non-contact voltage measuring devices along the width direction W may be further arranged.

A plurality of pairs of non-contact voltage measuring devices 2 may be arranged on both sides of the battery sheet 1 at locations corresponding to the measurement locations on the battery sheet 1 . More specifically, a plurality of pairs of non-contact voltage measuring devices 2 are stacked on the surface of the battery sheet 1 in a state separated from the measurement location and the location facing the measurement location in the stacking direction T. You may arrange|position so that the direction T may be opposed. Thereby, voltages at a plurality of locations on the surface of the battery sheet 1 can be measured simultaneously.

When a plurality of pairs of non-contact voltage measuring devices 2 are used, the arrangement of the non-contact voltage measuring devices 2 is not particularly limited. When the multiple pairs of non-contact voltage measuring devices 2 are arranged in a zigzag pattern, the multiple pairs of non-contact voltage measuring devices 2 may be arranged in a so-called zigzag pattern along the length direction. However, they may be arranged in a so-called zigzag shape along the width direction W.

When using a plurality of pairs of non-contact voltage measuring devices 2, the interval between adjacent non-contact voltage measuring devices 2 is not particularly limited, but is preferably equal.

FIG. 2 is a partially cutaway schematic perspective view showing an example of a battery sheet used as an inspection object in the battery sheet inspection method of the present invention.

A battery sheet (single cell) 10 shown in FIG. A negative electrode 13 having a negative electrode active material layer 16 provided on the surface of the negative electrode 19 is laminated with a substantially flat plate-shaped separator 14 interposed therebetween to form a substantially rectangular plate shape as a whole. Positive electrode 12 and negative electrode 13 function, for example, as a positive electrode and a negative electrode of a lithium ion battery, respectively.

The battery sheet 10 is arranged between the positive electrode resin current collector 17 and the negative electrode resin current collector 19 to fix the periphery of the separator 14 , and also includes the positive electrode active material layer 15 , the separator 14 and the negative electrode active material layer 16 . It is preferable to have an annular frame member 18 that seals the .

The positive electrode resin current collector 17 and the negative electrode resin current collector 19 are positioned by the frame member 18 so as to face each other with a predetermined gap, and the separator 14 and the positive electrode active material layer 15, and the separator 14 and the negative electrode active material layer. 16 are also positioned by a frame member 18 so as to face each other with a predetermined spacing.

The distance between the positive electrode resin current collector 17 and the separator 14 and the distance between the negative electrode resin current collector 19 and the separator 14 are adjusted according to the capacity of the battery sheet 10, for example, the lithium ion battery. In this manner, the positional relationship among the positive electrode resin current collector 17, the negative electrode resin current collector 19, and the separator 14 is determined so as to obtain the required spacing.

Preferred aspects of each component of the battery sheet are described below.

The positive electrode active material layer contains a positive electrode active material.

Examples of positive electrode active materials include composite oxides of lithium and transition metal {composite oxides containing one type of transition metal element (eg, LiCoO ₂ , LiNiO ₂ , LiAlMnO ₄ , LiMnO ₂ , LiMn ₂ O ₄ , etc.) , composite oxides containing two types of transition metal elements (for example, LiFeMnO ₄ , LiNi _1-x Co _x O ₂ , LiMn _1-y Co _y O ₂ , LiNi _1/3 Co _1/3 Al _1/3 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O _2, etc.), composite oxides containing three or more transition metal elements [for example, LiM _a M′ _b M″ _c O ₂ (M, M′, and M″ are respectively different transition metal elements _{and satisfy} a+b _{+ c} =1. salts (e.g., _LiFePO4 , _LiCoPO4 , _LiMnPO4 , LiNiPO4 _, etc.), transition metal oxides (e.g., _MnO2 , _{V2O5 ,} etc.), transition metal sulfides (e.g., _MoS2 , _TiS2, etc.), conductive polymers (eg, polyaniline, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene, polyvinylcarbazole, etc.); The lithium-containing transition metal phosphate may have a transition metal site partially substituted with another transition metal.

One of the positive electrode active materials described above may be used alone, or two or more of them may be used in combination.

The positive electrode active material is preferably a coated positive electrode active material coated with a conductive aid and a coating resin. When the positive electrode active material is coated with the coating resin, the volume change of the electrode is moderated, so expansion of the electrode can be suppressed.

Examples of conductive aids include metallic conductive aids [e.g., aluminum, stainless steel (SUS), silver, gold, copper, titanium, etc.], carbon-based conductive aids [e.g., graphite, carbon black (acetylene black, chain black, furnace black, channel black, thermal lamp black, etc.], mixtures thereof, alloys thereof, metal oxides thereof, and the like. Among them, from the viewpoint of electrical stability, aluminum, stainless steel, silver, gold, copper, titanium, carbon-based conductive additives, and mixtures thereof are preferable, and silver, gold, aluminum, stainless steel, and carbon-based conductive additives are preferable. agent is more preferable, and a carbon-based conductive aid is particularly preferable.

The conductive aid may be a particulate ceramic material or a resin material coated with a conductive material (preferably a metallic one among the conductive aids described above) by plating or the like.

One type of the conductive aids described above may be used alone, or two or more types may be used in combination.

The form (shape) of the conductive aid is not particularly limited, and may be in the form of particles, or may be in a form other than the form of particles. Regarding the conductive aid, the form other than the particle form may be a form that has been put into practical use as a so-called filler-based conductive aid, such as carbon nanofibers and carbon nanotubes.

The ratio of the coating resin and the conductive aid is not particularly limited, but from the viewpoint of the internal resistance of the battery, etc., the weight ratio of the coating resin (resin solid content weight): conductive aid is from 1:0.01. It is preferably 1:50, more preferably 1:0.2 to 1:3.0.

As the coating resin, those described as non-aqueous secondary battery active material coating resins in JP-A-2017-054703 are preferably used.

The positive electrode active material layer may further contain another conductive support agent in addition to the conductive support agent contained in the coated positive electrode active material.

As another conductive aid, the same one as the conductive aid contained in the above-described coated positive electrode active material is preferably used.

The positive electrode active material layer is preferably a non-binding material that contains a positive electrode active material and does not contain a binder (also referred to as a binder) that binds the positive electrode active materials together.

The non-bound body means that the position of the positive electrode active material is not fixed by a binder, and the positive electrode active material and the current collector are not fixed irreversibly. .

The positive electrode active material layer may further contain an adhesive resin.

As the adhesive resin, for example, a non-aqueous secondary battery active material coating resin described in JP-A-2017-054703 is mixed with a small amount of an organic solvent to adjust its glass transition temperature to room temperature or lower. Those described as adhesives in JP-A-10-255805 are preferably used.

Adhesive resin means a resin that does not solidify even when the solvent component is volatilized and dried, and has adhesiveness (the property of adhering by applying a slight pressure without using water, solvent, heat, etc.) do. On the other hand, a solution-drying type electrode binder used as a binding material is one that evaporates a solvent component to dry and solidify, thereby firmly adhering and fixing active materials to each other. Thus, the solution-drying type electrode binder (binder) and the adhesive resin are different materials.

Although the thickness of the positive electrode active material layer is not particularly limited, it is preferably 150 to 600 μm, more preferably 200 to 450 μm from the viewpoint of battery performance.

The negative electrode active material layer contains a negative electrode active material.

As the negative electrode active material, known negative electrode active materials for lithium ion batteries can be used. carbonized resin etc.), cokes (e.g., pitch coke, needle coke, petroleum coke, etc.), carbon fiber, etc.], silicon-based materials [e.g., silicon, silicon oxide (SiOx), silicon-carbon Composites (e.g., carbon particles coated with silicon and/or silicon carbide, silicon particles or silicon oxide particles coated with carbon and/or silicon carbide, silicon carbide, etc.), silicon alloys (e.g. , silicon-aluminum alloy, silicon-lithium alloy, silicon-nickel alloy, silicon-iron alloy, silicon-titanium alloy, silicon-manganese alloy, silicon-copper alloy, silicon-tin alloy, etc.)], conductive polymer ( polyacetylene, polypyrrole, etc.), metals (e.g., tin, aluminum, zirconium, titanium, etc.), metal oxides (e.g., titanium oxides, lithium-titanium oxides, etc.), metal alloys (e.g., lithium-tin alloys, lithium-aluminum alloys, lithium-aluminum-manganese alloys, etc.), mixtures of these with carbonaceous materials, and the like.

One type of the negative electrode active material described above may be used alone, or two or more types may be used in combination.

The negative electrode active material may be a coated negative electrode active material coated with a conductive aid and a coating resin. When the negative electrode active material is coated with the coating resin, the volume change of the electrode is moderated, so expansion of the electrode can be suppressed.

As the conductive aid and coating resin contained in the coated negative electrode active material, the same conductive aid and coating resin as those contained in the coated positive electrode active material described above are preferably used.

The negative electrode active material layer may further contain another conductive support agent in addition to the conductive support agent contained in the coated negative electrode active material.

As another conductive aid, the same one as the conductive aid contained in the above-described coated positive electrode active material is preferably used.

Like the positive electrode active material layer, the negative electrode active material layer is preferably a non-binding material that does not contain a binder that binds the negative electrode active materials together.

Like the positive electrode active material layer, the negative electrode active material layer may further contain an adhesive resin.

Although the thickness of the negative electrode active material layer is not particularly limited, it is preferably 150 to 600 μm, more preferably 200 to 450 μm from the viewpoint of battery performance.

Each of the positive electrode resin current collector and the negative electrode resin current collector is a resin current collector made of a conductive polymer material.

The form (shape) of the positive electrode resin current collector and the negative electrode resin current collector is not particularly limited, and may be a sheet-like current collector made of a conductive polymer material, or a conductive polymer material. It may be a deposited layer composed of fine particles composed of

The thickness of each of the positive electrode resin current collector and the negative electrode resin current collector is not particularly limited, but is preferably 50 to 500 μm.

Examples of the conductive polymer material that constitutes the positive electrode resin current collector and the negative electrode resin current collector include conductive polymers and resins to which a conductive agent is added as necessary.

As the conductive agent that constitutes the conductive polymer material, the same conductive aid as that contained in the above-described coated positive electrode active material is preferably used.

Examples of resins constituting conductive polymer materials include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polycycloolefin (PCO), polyethylene terephthalate (PET), and polyethernitrile (PEN). , polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVdF), epoxy resin, silicone resin, these and the like. Among them, from the viewpoint of electrical stability, polyethylene, polypropylene, polymethylpentene, and polycycloolefin are preferred, and polyethylene, polypropylene, and polymethylpentene are more preferred.

The resins described above may be used singly or in combination of two or more.

As the separator, known lithium ion battery separators can be used. Aramid fiber, etc.) or nonwoven fabric made of glass fiber, etc., and those having ceramic fine particles such as silica, alumina, titania, etc. adhered to the surface thereof.

The battery sheet includes an electrolyte present in the positive electrode active material layer and the negative electrode active material layer.

As the electrolytic solution, a known electrolytic solution containing an electrolyte and a non-aqueous solvent, which is used in the production of known lithium ion batteries, can be used.

_{As the} electrolyte _, those used in _known electrolytic solutions _{can be} used _. Lithium salts of organic acids such as LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ and LiC(CF ₃ SO ₂ ) ₃ are included. Among them, imide-based electrolytes such as LiN(FSO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ and LiPF ₆ are preferred from the viewpoint of battery output and charge-discharge cycle characteristics. preferable.

As the non-aqueous solvent, those used in known electrolytic solutions can be used. compounds, amide compounds, sulfones, sulfolane, mixtures thereof, and the like.

The electrolyte concentration of the electrolytic solution is preferably 1 to 5 mol/L, more preferably 1.5 to 4 mol/L, still more preferably 2 to 3 mol/L.

If the electrolyte concentration of the electrolytic solution is lower than 1 mol/L, the battery may not have sufficient input/output characteristics. If the electrolyte concentration of the electrolytic solution is higher than 5 mol/L, the electrolyte may precipitate.

The electrolyte concentration of the electrolytic solution can be confirmed by extracting the electrolytic solution from a battery sheet, for example, a lithium ion battery without using a solvent or the like and measuring the concentration.

[Method for manufacturing battery sheet]
The method for manufacturing a battery sheet of the present invention includes a sorting step of sorting out battery sheets that have been determined to have no short-circuited portions by the battery sheet inspection method of the present invention.

In the battery sheet manufacturing method of the present invention, the sorting step can efficiently obtain a battery sheet free of short-circuited portions while removing defective products having short-circuited portions.

[Method for manufacturing assembled battery]
The method for manufacturing an assembled battery of the present invention includes a stacking step of stacking a plurality of battery sheets that have been determined to have no short-circuited portions by the battery sheet inspection method of the present invention.

FIG. 3 is a partially cutaway schematic perspective view showing an example of an assembled battery. FIG. 3 shows a state in which a portion of the exterior body is removed.

The assembled battery 100 shown in FIG. 3 is formed by stacking and connecting a plurality of battery sheets 10 . The example shown in FIG. 3 shows a state in which five battery sheets 10 shown in FIG. 2 are stacked. In the assembled battery 100, the battery sheets 10 are laminated such that the upper surface of the negative electrode resin current collector 19 and the lower surface of the positive electrode resin current collector 17 are adjacent to each other. In this case, a plurality of battery sheets 10 are connected in series.

The assembled battery 100 is housed in an exterior body 110 .

Examples of the exterior body 110 include a metal can case, a polymer-metal composite film, and the like.

A conductive sheet is provided on the surface of the positive electrode resin current collector that constitutes the bottom surface of the assembled battery 100 . A part of the conductive sheet is pulled out from the outer package 110 to serve as a positive electrode extraction terminal 120 .

Another conductive sheet is provided on the surface of the negative electrode resin current collector that constitutes the uppermost surface of the assembled battery 100 . A part of another conductive sheet is pulled out from the outer package 110 to serve as a negative electrode extraction terminal 130 .

The constituent material of the conductive sheet that serves as the positive electrode lead terminal 120 and the negative electrode lead terminal 130 is not particularly limited as long as it is a material having conductivity, and examples thereof include copper, aluminum, titanium, stainless steel, nickel, and alloys thereof. metal, calcined carbon, conductive polymer, conductive glass, and the like.

In the battery sheet inspection method of the present invention, even minute short circuits on the order of several millimeters can be found. As a result, in the assembled battery manufacturing method of the present invention, the assembled battery can be manufactured using the battery sheet without any defects, and thus the manufacturing yield of the assembled battery can be improved.

The battery sheet to be inspected by the battery sheet inspection method of the present invention is particularly useful for lithium ion batteries used in mobile phones, personal computers, hybrid vehicles, and electric vehicles.

1, 10 Battery sheet (cell)
2 Non-contact voltage measuring device 12 Positive electrode 13 Negative electrode 14 Separator 15 Positive electrode active material layer 16 Negative electrode active material layer 17 Positive electrode resin current collector 18 Frame member 19 Negative electrode resin current collector 100 Assembled battery 110 Armor body 120 Positive electrode extraction terminal 130 Negative electrode Lead terminal L Length direction T Stacking direction W Width direction

Claims (5)

A battery sheet having a positive electrode resin current collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode resin current collector, which are laminated in order in the stacking direction, as an object to be inspected, and using a non-contact voltage measuring device. a measuring step of measuring voltages at a plurality of locations on the surface of the battery sheet while being separated from the surface of the battery sheet;
and a determination step of determining whether or not a short-circuited portion exists in the battery sheet based on the voltage. 2. The method according to claim 1, wherein in the measuring step, the non-contact voltage measuring device is arranged so as to face the stacking direction while being separated from a portion of the surface of the battery sheet facing the stacking direction. A method for inspecting the described battery sheet. 3. The method of inspecting a battery sheet according to claim 1, wherein in said measuring step, said battery sheet is passed through a region in which said non-contact voltage measuring device is arranged facing said stacking direction. A method for producing a battery sheet, comprising a sorting step of sorting out battery sheets determined to have no short-circuited portions by the battery sheet inspection method according to any one of claims 1 to 3. Manufacture of an assembled battery, comprising a stacking step of stacking a plurality of battery sheets for which the battery sheet inspection method according to any one of claims 1 to 3 determines that there is no short circuit. Method.

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