Battery inspection method and battery manufacturing method

Abstract

To provide an inspection method of a battery, capable of determining the presence / absence of a short circuit with high accuracy.SOLUTION: An inspection method of a battery, includes: an electrode assembly preparation step; an electrolyte liquid inspection step; a sealing step; and a short circuit determination step. An electrode assembly includes a non-facing region other than a region where a positive electrode active material layer and a negative electrode active material layer face each other. The short circuit determination step is a step where the presence / absence of the short circuit are determined by at least one method of the following methods (i) and (ii) before an initial charging. (i) a voltage of a power generation unit is measured under an atmospheric pressure, and when a measurement value of the voltage of the power generation unit is 0 V, it is determined that the short circuit occurs in the power generation unit. In the case where (ii) the voltage of the battery is measured under the atmospheric pressure, and the measurement value of the voltage of the battery is lower than a reference value obtained by multiplying an open circuit voltage of the power generation unit that is specified to a material of the positive electrode active material layer and a material of the negative electrode active material layer by the number of the power generation unit included in the battery, it is determined that the short circuit occurs in the battery.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a battery inspection method and a battery manufacturing method. [Background technology]

[0002] Various methods have been proposed for testing batteries for short circuits.

[0003] For example, Patent Document 1 discloses a method for testing a bipolar battery for short circuits, which includes the steps of forming a stack having a plurality of bipolar electrodes, applying pressure to the stack, measuring a measurement value according to the magnitude of the electrostatic capacitance between a positive terminal electrode and a negative terminal electrode of the stack, and determining whether or not a short circuit has occurred within the stack based on the measurement value.

[0004] Patent Document 2 discloses a method for detecting short circuits in batteries. In this method, an electrode group, which is made up of stacked positive and negative electrode plates and separators, is housed in a battery case, helium gas is injected into the battery case, and a predetermined voltage is applied between the positive and negative terminals in the presence of helium to detect the presence or absence of a short circuit in the electrode group. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-202019 A [Patent Document 2] Japanese Patent Application Publication No. 11-297368 Summary of the Invention [Problem to be solved by the invention]

[0006] There are cases where foreign matter is mixed in the opposing portion of the positive electrode active material layer and the negative electrode active material layer, and the foreign matter breaks through the separator, causing a short circuit. Therefore, for example, in a bipolar battery, there is a method in which, before injecting an electrolyte, the electrode assembly is pressurized in the thickness direction and a voltage is applied to the positive and negative electrodes at the start and end of the stack. With this method, it is possible to detect a short circuit from the resistance calculated from the flowing current and the applied voltage.

[0007] On the other hand, in the non-opposing region other than the region where the positive electrode active material layer and the negative electrode active material layer face each other, pressure is not applied during pressurization, making it difficult to inspect. If a foreign object is present in the non-opposing region, a short circuit may occur when the pressure inside the battery is reduced in a charged state.

[0008] In addition, foreign matter may get into the battery during the electrolyte injection process. Therefore, it is necessary to perform a short circuit inspection after the electrolyte injection process. However, after the electrolyte injection process, current does not concentrate at the short circuit even if a voltage is applied, so it is impossible to detect the short circuit.

[0009] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a battery inspection method that can determine the presence or absence of a short circuit with high accuracy. [Means for solving the problem]

[0010] [1] A battery inspection method, the method comprising a preparation step, a liquid injection step, a sealing step, and a short circuit determination step, the preparation step being a step of preparing an electrode assembly including a positive electrode active material layer and a negative electrode active material layer, the electrode assembly having a non-opposing region other than a region where the positive electrode active material layer and the negative electrode active material layer face each other, the liquid injection step being a step of injecting an electrolyte into the electrode assembly to obtain a battery having a plurality of power generation units connected in series, the sealing step being a step of sealing the battery under reduced pressure, and the short circuit determination step being a step of determining whether or not a short circuit has occurred by performing the following (i) before an initial charge: and a step of determining the presence or absence of a short circuit by at least one of the following methods (ii): (i) measuring the voltage of the power generation unit under atmospheric pressure, and determining that a short circuit has occurred in the power generation unit if the measured voltage of the power generation unit is 0 V, and (ii) measuring the voltage of the battery under atmospheric pressure, and determining that a short circuit has occurred in the battery if the measured voltage of the battery is lower than a reference value obtained by multiplying the number of power generation units contained in the battery by an open circuit voltage of the power generation unit that is specific to the material of the positive electrode active material layer and the material of the negative electrode active material layer.

[0011] [2] The battery inspection method according to [1], wherein the electrode assembly includes a plurality of stacked bipolar electrodes.

[0012] [3] A battery inspection method as described in [1] or [2], in which, in the short circuit determination step, after it is determined that a short circuit has occurred in the battery by the method (ii) above, the presence or absence of a short circuit is further determined for each of the power generation units by the method (i) above.

[0013] [4] A method for manufacturing a battery, the method comprising a preparation step, a liquid injection step, a sealing step, and a short circuit determination step, the preparation step being a step of preparing an electrode assembly including a positive electrode active material layer and a negative electrode active material layer, the electrode assembly having a non-opposing region other than a region where the positive electrode active material layer and the negative electrode active material layer face each other, the liquid injection step being a step of injecting an electrolyte into the electrode assembly to obtain a battery having a power generation unit, the sealing step being a step of sealing the battery under reduced pressure, and the short circuit determination step being a step of determining the presence or absence of a short circuit by the following method (i) before an initial charge: (i) measuring the voltage of the power generation unit under atmospheric pressure, and if the measured voltage of the power generation unit is 0 V, determining that a short circuit has occurred in the power generation unit.

[0014] [5] A battery manufacturing method comprising an inspection step and a charging step, the inspection step being a step of carrying out a battery inspection method described in any one of [1] to [4], and the charging step being a step of initially charging the battery that has not been determined to have a short circuit. Effect of the Invention

[0015] The present disclosure provides an advantage in that the presence or absence of a short circuit can be inspected with high accuracy. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a process flow diagram illustrating a battery inspection method according to the first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic cross-sectional view illustrating an electrode assembly in the first embodiment of the present disclosure. [Diagram 3] FIG. 3 is a schematic cross-sectional view for explaining the liquid injection step in the first embodiment of the present disclosure. [Figure 4] FIG. 4 is a schematic cross-sectional view for explaining the sealing step in the first embodiment of the present disclosure. [Diagram 5] FIG. 5 is a schematic cross-sectional view illustrating a short circuit determination step in the first embodiment of the present disclosure. [Figure 6] FIG. 6 is a schematic cross-sectional view (exploded view) illustrating a method for producing the electrode assembly in the first embodiment of the present disclosure. [Figure 7] FIG. 7 is a process flow diagram illustrating a battery inspection method according to the second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present disclosure will be described in detail below with reference to the drawings. The drawings are merely examples, and the size and shape of each part may be exaggerated to facilitate understanding.

[0018] A. Battery Inspection Method (First Embodiment) 1 is a process flow diagram of a battery inspection method according to the present embodiment. As shown in FIG 1, the battery inspection method according to the present embodiment includes a preparation step (S1), a liquid injection step (S2), a sealing step (S3), and a short circuit determination step (S4).

[0019] In this embodiment, the inside of the battery is in a reduced pressure state in the sealing step (S3). Therefore, when the battery is taken out under atmospheric pressure in the short circuit determination step (S4), all parts including the non-facing region are pressurized. Therefore, the presence or absence of a short circuit is determined with high accuracy by at least one of the following methods (i) and (ii) described below. Furthermore, foreign matter may be mixed in during the electrolyte injection step (S2). It is possible to detect a short circuit caused by such foreign matter. In particular, the presence or absence of a short circuit in a bipolar stacked battery is inspected with high accuracy. Each step will be described in detail.

[0020] 1. Preparation process This step is a step of preparing an electrode assembly including a positive electrode active material layer and a negative electrode active material layer. The electrode assembly has a non-facing region. The non-facing region is a region other than the region where the positive electrode active material layer and the negative electrode active material layer face each other when viewed from the z-axis direction.

[0021] The electrode assembly in this embodiment has two or more precursors of the power generation unit. FIG. 2 is a schematic cross-sectional view illustrating an electrode assembly in the present disclosure. As shown in FIG. 2, the electrode assembly 10 preferably has a plurality of the above precursors P (P1 to P30) stacked in the z-axis direction. The precursor P of the power generation unit has a positive electrode active material layer 2, a negative electrode active material layer 3, and a separator 4 disposed between the positive electrode active material layer 2 and the negative electrode active material layer 3. The electrode assembly has a non-facing region X other than the region where the positive electrode active material layer 2 and the negative electrode active material layer 3 face each other.

[0022] As shown in FIG. 2, the electrode assembly 10 may include a plurality of electrodes E stacked in the z-axis direction. The electrode assembly 10 shown in FIG. 2 has bipolar electrodes BP (BP1 to BP29) as the electrodes E. The electrode assembly 10 further has a positive end electrode CA and a negative end electrode AN. The bipolar electrode BP has a current collector 1, a positive electrode active material layer 2, and a negative electrode active material layer 3. The positive electrode active material layer 2 is disposed on one surface of the current collector 1, and the negative electrode active material layer 3 is disposed on the other surface of the current collector 1. The positive electrode end electrode CA has a current collector 1 and a positive electrode active material layer 2. The positive electrode active material layer 2 is disposed on one surface of the current collector 1. The negative electrode end electrode AN has a current collector 1 and a negative electrode active material layer 3. The negative electrode active material layer 3 is disposed on one surface of the current collector 1.

[0023] The electrode assembly 10 in this embodiment may have only one bipolar electrode BP, or may have two or more bipolar electrodes BP. On the other hand, the battery in the present disclosure does not necessarily have to have a bipolar electrode.

[0024] In this embodiment, the plurality of precursors P (P1 to P30) are directly connected to each other as shown in Fig. 2. The plurality of precursors are independent of each other so that the electrolyte does not flow between them.

[0025] The precursor of one power generation unit may be composed of two bipolar electrodes. For example, as shown in Fig. 2, the precursor P2 of the power generation unit is composed of a positive electrode active material layer 2 in a bipolar electrode BP2, a negative electrode active material layer 3 in a bipolar electrode BP1, and a separator 4 disposed therebetween.

[0026] As shown in FIG. 2, a frame-shaped sealing member 5 is preferably disposed along the outer edge of the current collector 1 as viewed from the z-axis direction. The sealing member is preferably a resin member. Examples of resins constituting the resin member include thermoplastic resins. Examples of thermoplastic resins include olefin-based resins such as polyethylene and polypropylene. As shown in FIG. 2, the sealing member 5 preferably has a through hole O for supplying an electrolyte to the inside of the electrode assembly 10. As shown in FIG. 2, the through hole O preferably extends in the x-axis direction.

[0027] The shape of the electrode assembly in plan view (shape as viewed from the z-axis direction) is not particularly limited, but examples include quadrilaterals such as squares and rectangles. The length of one side in the shape of the battery in plan view is, for example, 30 cm or more, may be 50 cm or more, or may be 100 cm or more. On the other hand, the length of one side is, for example, 200 cm or less.

[0028] The method for producing the electrode assembly is not particularly limited. FIG. 6 is a schematic cross-sectional view illustrating a method for producing an electrode assembly in the present disclosure. As shown in FIG. 6(a), a plurality of bipolar electrodes BP are prepared. The bipolar electrodes BP have a frame member 5a for forming a seal member, which is arranged along the outer edge of the current collector 1. When viewed from the z-axis direction, the frame member 5a is usually arranged along the entire outer edge of the current collector 1. For example, when the outer edge shape of the current collector 1 is a rectangle, the frame member 5a is arranged along the entire outer edge of the rectangle.

[0029] As shown in FIG. 6(a), the negative electrode active material layer 3 in the bipolar electrode BP1 and the positive electrode active material layer 2 in the bipolar electrode BP2 are opposed to each other with a separator 4 interposed therebetween. At this time, at least a part of the outer edge of the separator 4 is disposed between the frame members 5a. Also, as shown in FIG. 6(a), a nest 6 and a frame member (spacer) 5b are disposed between the frame members 5a in the bipolar electrode BP1 and the frame members 5a in the bipolar electrode BP2. Next, although not shown in particular, the positive electrode end electrode CA and the negative electrode end electrode AN are laminated on the bipolar electrodes BP1 and BP2, respectively, with the separator 4 interposed therebetween. After that, a seal member is formed by welding the laminated frame members. In this way, an electrode assembly 10 with the nest inserted is obtained, as shown in FIG. 6(b). By removing the nest, an electrode assembly with a through hole formed therein is obtained.

[0030] 2. Liquid injection process The liquid injection step in this embodiment is a step of injecting an electrolyte into the electrode assembly to obtain a battery having a plurality of generating units connected in series. FIG. 3 is a schematic cross-sectional view for explaining the liquid injection step in this embodiment. As shown in FIG. 3, the electrolyte L is supplied into the electrode assembly 10 through the through-hole O. This causes the electrolyte L to be supplied to the positive electrode active material layer 2, the negative electrode active material layer 3, and the separator 4. As a result, the positive electrode active material layer 2, the negative electrode active material layer 3, and the separator 4 are each impregnated with the electrolyte L. In addition, a battery 20 having a plurality of generating units U (U1 to U30) connected in series is obtained. As shown in FIG. 3, the battery 20 is preferably a bipolar laminated battery.

[0031] The method of injecting the electrolyte is not particularly limited, and for example, a known method using an electrolyte injection device can be used. As the electrolyte, for example, a known organic electrolyte used in a lithium ion secondary battery can be appropriately used.

[0032] 3.Sealing process The sealing step in this embodiment is a step of sealing the battery under reduced pressure after the electrolyte injection step. FIG. 4 is a schematic cross-sectional view for explaining the sealing step in the present disclosure. For example, the battery 20 after the electrolyte injection step is placed in a chamber 40, and the chamber 40 is evacuated. Thereafter, as shown in FIG. 4, a sealing member 41 is placed on the through hole O, and the sealing member 41 and the seal member 5 are welded together. This allows the battery 20 to be sealed under reduced pressure, and all parts including the non-facing region X are in a negative pressure state. Therefore, a short circuit can be detected by a short circuit determination step described later.

[0033] 4. Short circuit determination process The battery inspection method in this embodiment includes a short circuit determination step, which is a step of determining the presence or absence of a short circuit before the initial charge by at least one of the following methods (i) and (ii): (i) Under atmospheric pressure, the voltage of the generating unit is measured, and if the measured voltage of the generating unit is 0 V, it is determined that a short circuit has occurred in the generating unit. (ii) The voltage of the battery is measured under atmospheric pressure. If the measured voltage of the battery is lower than a reference value obtained by multiplying the number of power generation units contained in the battery by the open circuit voltage of a power generation unit specific to the material of the positive electrode active material layer and the material of the negative electrode active material layer, it is determined that a short circuit has occurred in the battery.

[0034] FIG. 5 is a schematic cross-sectional view illustrating a short circuit determination step in the present disclosure. As shown in FIG. 5, when the chamber is opened after the sealing step, the outermost foils of the battery 20 (the current collector 1 of the positive end electrode CA and the current collector 1 of the negative end electrode AN) are pressed by atmospheric pressure. At this time, the non-facing area X is also pressed by atmospheric pressure. If a foreign object Z is present, the foreign object Z is pressed against the separator 4. If the foreign object Z is large, the separator 4 is broken. In this step, at least one of the voltage of the power generation unit and the voltage of the battery is measured under atmospheric pressure.

[0035] In the short-circuit determination step of the present disclosure, if the voltage measurement value of the power generation unit is 0V, it may be determined that a short circuit has occurred in the power generation unit (method (i) above).

[0036] After the liquid injection step, an open circuit voltage specific to the material is generated in each power generation unit due to the difference between the natural potential of the positive electrode active material and the natural potential of the negative electrode active material. However, a short circuit may occur in a power generation unit that contains foreign matter. The voltage of a power generation unit in which a short circuit has occurred is usually 0V. Therefore, if the measured voltage value of a power generation unit is 0V, it can be determined that a short circuit has occurred. Furthermore, according to the above method (i), since it is determined whether the measured voltage value is 0V or not, it is possible to detect a short circuit with high accuracy.

[0037] The voltage of each power generating unit can be measured by measuring the voltage between the positive and negative terminals of the power generating unit. The voltage measurement may be performed by a conventionally known method.

[0038] In the short circuit determination step of the present disclosure, if the measured voltage value of the battery is lower than a reference value, it may be determined that the battery is short circuited (method (ii) above). The reference value is the number of power generation units contained in the battery multiplied by the open circuit voltage of the power generation unit specific to the material of the positive electrode active material layer and the material of the negative electrode active material layer. By using method (ii) above, the presence or absence of a short circuit can be determined by measuring the total voltage of the battery, without having to measure the voltage of each power generation unit individually.

[0039] When the battery is a bipolar laminated battery, the voltage of the battery 20 can be measured by measuring the total voltage between the current collector 1 of the positive end electrode CA and the current collector 1 of the negative end electrode AN with a voltmeter 50, as shown in FIG. 5.

[0040] In the method (ii), a reference value V0 is used. The reference value V0 is the number (N) of generating units contained in the battery multiplied by the open circuit voltage (V1) of the generating unit specific to the material of the positive electrode active material layer and the material of the negative electrode active material layer. In other words, the reference value V0 [V] is V1 [V] × N [cells]. The "open circuit voltage of the generating unit specific to the material of the positive electrode active material layer and the material of the negative electrode active material layer" is the natural potential difference generated during injection, which is specific to the type of positive electrode active material and the type of negative electrode active material. The above open circuit voltage is obtained by measuring in advance.

[0041] As described above, the voltage of a power generation unit that has experienced a short circuit is usually 0 V. Therefore, when a battery has one shorted power generation unit, the measured voltage of the battery is the open circuit voltage V1 of the power generation unit multiplied by N-1 (= V1 × (N-1) [V]). When a battery has two shorted power generation units, the measured voltage of the battery is the open circuit voltage V1 of the power generation unit multiplied by N-2 (= V1 × (N-2) [V]).

[0042] For example, when the positive electrode active material is LFP (lithium iron phosphate) and the negative electrode active material is graphite, the open circuit voltage of the power generation unit is measured to be about 0.1 V. The battery 20 as shown in Fig. 5 has 30 power generation units. Therefore, the reference value V0 is 0.1 [V] x 30 [cells] = 3 [V].

[0043] However, if the battery has one shorted generating unit, the battery voltage measurement is about 2.9 V. If the battery has two shorted generating units, the battery voltage measurement is about 2.8 V.

[0044] In this way, if the battery voltage measurement value V is lower than the reference value V0 (= V1 [V] × N [cells]), it can be determined that the battery is short-circuited. Also, if the battery voltage measurement value V is equal to or lower than V1 [V] × (N-1) [cells], it may be determined that the battery is short-circuited.

[0045] The short circuit determination step in this embodiment may combine both methods (ii) and (i). For example, after it is determined that a short circuit has occurred in the battery by method (ii), a short circuit determination can be further performed for each power generation unit by method (i). This makes it possible to detect the power generation unit in the stacked battery that has a short circuit.

[0046] B. Battery Inspection Method (Second Embodiment) Fig. 7 is a process flow diagram of the battery inspection method in this embodiment. As shown in Fig. 7, the battery inspection method in this embodiment includes a preparation step (S1), a liquid injection step (S2), a sealing step (S3), and a short circuit determination step (S4). Each step will be described in detail.

[0047] 1. Preparation process This step is a step of preparing an electrode assembly including a positive electrode active material layer and a negative electrode active material layer. The electrode assembly has a non-facing region other than the region where the positive electrode active material layer and the negative electrode active material layer face each other. The electrode assembly in this embodiment may have only one precursor of the power generation unit. Also, the electrode assembly in this embodiment may have two or more precursors of the power generation unit.

[0048] 2. Liquid injection process The liquid injection step in this embodiment is a step of injecting an electrolyte into the electrode assembly to obtain a battery having a power generation unit. The battery may be a single cell having one power generation unit. The battery may have two or more power generation units. When the battery has multiple power generation units, the multiple power generation units may be connected in series with each other. The multiple power generation units may be connected in parallel with each other.

[0049] 3.Sealing process The sealing step in this embodiment is a step of sealing the battery under reduced pressure after the electrolyte injection step. The sealing step can be performed in the same manner as in the first embodiment.

[0050] 4. Short circuit determination process The short circuit determination step in this embodiment is a step of determining the presence or absence of a short circuit by the following method (i) before the initial charge: (i) The voltage of the power generation unit is measured under atmospheric pressure, and if the measured voltage of the power generation unit is 0 V, it is determined that a short circuit has occurred in the power generation unit.

[0051] The short circuit determination step in this embodiment can be performed in the same manner as the method (i) in the short circuit determination step in the first embodiment. For example, in the case of a single cell, the voltage between the positive and negative terminals is measured. This makes it possible to determine whether or not a short circuit has occurred in the power generation unit (battery).

[0052] C. Battery manufacturing method The method for manufacturing a battery according to the present disclosure includes an inspection step and a charging step.

[0053] 1.Inspection process The inspection step is a step of inspecting a battery having a power generation unit. As a method for inspecting a battery, the above-mentioned battery inspection method can be adopted.

[0054] 2.Charging process The charging step is a step of initially charging the batteries that are not determined to have a short circuit. The above inspection step allows the selection of batteries that are not short-circuited. The selected batteries are initially charged according to a standard method, allowing the batteries to be manufactured.

[0055] Since there is no need to charge the unselected electrode assemblies thereafter, waste in the battery manufacturing process can be eliminated.

[0056] 3.Battery Specific examples of the battery in the present disclosure include a secondary battery (e.g., a lithium-ion secondary battery) and an electric double layer capacitor. In addition, examples of uses of the battery include a power source for vehicles such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an electric vehicle (BEV), a gasoline vehicle, and a diesel vehicle. In particular, it is preferable to use the battery as a driving power source for a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or an electric vehicle (BEV). In addition, the battery in the present disclosure may be used as a power source for a moving body other than a vehicle (e.g., a train, a ship, an aircraft), or as a power source for an electric product such as an information processing device. EXAMPLES

[0057] The present disclosure will now be further described with reference to examples.

[0058] (Example) As shown in FIG. 2, an electrode assembly 10 was prepared in which bipolar electrodes BP were stacked. In the bipolar electrode BP, the positive electrode active material layer contains LFP (lithium iron phosphate), and the negative electrode active material layer contains graphite. As shown in FIG. 3, an electrolyte was injected into the electrode assembly from the injection port O of the electrode assembly 10. As a result, a bipolar stacked battery 20 having 30 power generation units U connected in series was obtained. From the open circuit voltage of the power generation unit measured in advance of 0.1 V, the reference value was calculated to be 3.0 V (= 0.1 [V] × 30 [cells]). At this time, a foreign object having a length of 200 μm was put into the stacked battery from the injection port O. Next, as shown in FIG. 4, the bipolar stacked battery 20 was placed in a chamber 40 and evacuated. As a result, the inside of the stacked battery 20 was put into a reduced pressure state. Next, the injection port O was sealed using a sealing member 41. Next, as shown in FIG. 5, the chamber 40 was opened to atmospheric pressure. Next, the voltage between the outermost foils (current collector 1 of the positive end electrode CA and current collector 1 of the negative end electrode AN) was measured. Since the measured voltage was 2.9V, it was determined that a short circuit had occurred in the battery. It was also inferred that the short circuit occurred in one power generation unit.

[0059] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included in the technical scope of the present disclosure. [Explanation of symbols]

[0060] 1...Current collector 2...Cathode active material layer 3...Negative electrode active material layer 4…Separator 5…Sealing material 6…Nesting 10...Electrode assembly 20...Battery O...Through hole

Claims

1. A battery inspection method, the method comprising: a preparation step, a liquid injection step, a sealing step, and a short circuit determination step, the preparation step being a step of preparing an electrode assembly including a positive electrode active material layer and a negative electrode active material layer, the electrode assembly having a non-opposing region other than a region where the positive electrode active material layer and the negative electrode active material layer oppose each other, the liquid injection step being a step of injecting an electrolyte into the electrode assembly to obtain a battery having a plurality of power generation units connected in series, the sealing step being a step of sealing the battery under reduced pressure, and the short circuit determination step being a step of determining the presence or absence of a short circuit by at least one of the following methods (i) and (ii) before an initial charge: (i) measuring the voltage of the power generation unit under atmospheric pressure, and determining that a short circuit has occurred in the power generation unit when the measured voltage of the power generation unit is 0 V; (ii) The voltage of the battery is measured under atmospheric pressure, and if the measured voltage of the battery is lower than a reference value obtained by multiplying the number of the power generation units contained in the battery by an open circuit voltage of the power generation unit that is specific to the material of the positive electrode active material layer and the material of the negative electrode active material layer, it is determined that a short circuit has occurred in the battery.

2. The method for testing a battery according to claim 1 , wherein the electrode assembly includes a plurality of stacked bipolar electrodes.

3. 2. A battery inspection method as described in claim 1, wherein, in the short circuit determination step, after it is determined that a short circuit has occurred in the battery by the method (ii), the presence or absence of a short circuit is further determined for each of the power generation units by the method (i).

4. A battery inspection method, the method comprising: a preparation step, a liquid injection step, a sealing step, and a short circuit determination step, the preparation step being a step of preparing an electrode assembly including a positive electrode active material layer and a negative electrode active material layer, the electrode assembly having a non-opposing region other than a region where the positive electrode active material layer and the negative electrode active material layer face each other, the liquid injection step being a step of injecting an electrolyte into the electrode assembly to obtain a battery having a power generation unit, the sealing step being a step of sealing the battery under reduced pressure, and the short circuit determination step being a step of determining the presence or absence of a short circuit by the following method (i) before an initial charge: (i) The voltage of the power generating unit is measured under atmospheric pressure, and if the measured voltage of the power generating unit is 0 V, it is determined that a short circuit has occurred in the power generating unit.

5. A method for manufacturing a battery, the method having an inspection step and a charging step, the inspection step being a step of performing a battery inspection method described in any one of claims 1 to 4, and the charging step being a step of performing an initial charge on the battery that has not been determined to have a short circuit.

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