Manufacturing method for battery pack

Abstract

To make it possible to effectively use in other applications such as stationary storage batteries without discarding batteries, in particular, whose electrical characteristics, such as capacity, no longer meet certain standards among various batteries whose deterioration states differ depending on their usage conditions.SOLUTION: By measuring the impedance values of various battery groups with different states such as capacity in advance, and by calculating the parallel impedance value when these batteries are connected in parallel in any combination, it is made possible to create a parallel unit having a predetermined impedance value even with combinations including low-capacity batteries. Furthermore, by connecting these parallel units in series to form a battery pack, it is made possible to effectively utilize batteries that would otherwise be discarded at low cost without using high-performance control devices.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a battery pack, and in particular to a technique for effectively reusing batteries in different states for other purposes at low cost. [Background technology]

[0002] In recent years, the problem of depletion of fossil fuel resources, coupled with the problem of environmental burden such as greenhouse gas emissions, has led to a worldwide shift from gasoline-powered vehicles to electric vehicles, and their popularity is rapidly increasing. Lithium-ion batteries installed in electric vehicles deteriorate with use, and usually, when they no longer meet a certain capacity standard, they need to be replaced. However, used batteries collected from electric vehicles may be fully usable for other purposes, even if they do not meet the standards for use in electric vehicles.

[0003] For this reason, in order to efficiently utilize battery resources, active efforts are being made to reuse used batteries collected from electric vehicles for other purposes such as stationary storage batteries (see, for example, Patent Documents 1 to 6). Used batteries deteriorate differently depending on the conditions of use, so they are usually disassembled into single cells or battery modules, the performance of each battery unit is measured, and they are grouped. Used batteries that meet the purpose of reuse are selected and reassembled for commercialization. In recent years, attention has been focused on the use of renewable energy such as solar power, and the demand for stationary storage batteries is also increasing. Stationary storage batteries made from such reused batteries have the advantage of not only making effective use of resources, but also being able to be introduced at low cost. In addition, it extends the life cycle of used batteries that were previously recycled, and contributes to the realization of a decarbonized society by expanding the use of renewable energy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-216328 A [Patent Document 2] JP 2016-152110 A [Patent Document 3] JP 2019-204679 A [Patent Document 4] JP 2013-110069 A [Patent Document 5] JP 2017-79131 A [Patent Document 6] Patent Publication No. 2021-48007 [Non-patent literature]

[0005] [Non-Patent Document 1] Toyota Central R&D Labs., Inc., News Release, October 27, 2022, https: / / www.tytlabs.co.jp / assets / pdf / news / 2429 / news-release.pdf Summary of the Invention [Problem to be solved by the invention]

[0006] In such a scheme for reusing used batteries, it is necessary to select cells or battery modules that are grouped according to their deterioration state according to the purpose of reuse, but it is difficult to collect multiple batteries in the same state because the deterioration state of the batteries varies depending on the usage conditions. Also, the current situation is that batteries whose electrical characteristics such as capacity do not meet certain standards must be discarded and recycled for raw materials, even though they may still be usable.

[0007] To address these issues, a technology has been developed recently that makes effective use of a variety of used batteries with different performance by connecting multiple used batteries of different types and conditions in series and controlling the energization / de-energization during use according to the characteristics of each battery (see Non-Patent Document 1). However, this technology requires that each used battery be controlled by a device, which increases the introduction and maintenance costs, and does not fully utilize the benefits of using low-cost used batteries.

[0008] On the other hand, new batteries that do not pass the strict product inspection by the manufacturer cannot be shipped. For this reason, only batteries that fall within a certain range of capacity, output voltage, etc. are allowed to be shipped as new battery products, and batteries that do not meet the product conditions even slightly in these characteristics must be discarded as defective products, even if they may be fully usable for some applications. From the viewpoint of the battery life cycle, it is considered desirable to recycle such defective batteries after using them for appropriate purposes, as long as they at least meet the safety standards.

[0009] An object of the present invention is to provide a method for effectively utilizing, at low cost, batteries that, among various batteries of different states, no longer satisfy certain standards in terms of electrical characteristics, particularly capacity, for other purposes, such as stationary storage batteries, without having to be discarded. [Means for solving the problem]

[0010] As a result of intensive research conducted by the present inventors in consideration of the problems with the conventional technology, it has been discovered that by measuring in advance the impedance values ​​of various battery groups differing in state, such as capacity, and calculating the parallelized impedance value when these batteries are parallelized in any combination, it is possible to create a parallelized unit that provides a predetermined impedance value for a combination including low-capacity batteries, and further by connecting these parallelized units in series to form a battery pack, it is possible to effectively utilize batteries that would conventionally have been discarded at low cost, without using high-performance control devices, etc., and has thus completed the present invention.

[0011] That is, the manufacturing method of the battery pack of the present invention is characterized by comprising an impedance measuring step of measuring the impedance value of each battery in a battery group consisting of a plurality of single cells or battery modules, a parallelization impedance calculating step of selecting any combination of a plurality of batteries each having different impedance values ​​from the battery group whose impedance values ​​have been measured in the above step, and calculating a parallelization impedance value when the combination of the plurality of batteries is parallelized, a parallelization combination determining step of determining two or more battery combinations such that the parallelization impedance value falls within a preset allowable range of impedance values, a parallelization unit creating step of parallelizing two or more of the battery combinations determined in the above step, and a serialization step of serializing the two or more parallelization units created in the above step.

[0012] In the method for producing a battery pack of the present invention, it is preferable that in the impedance measuring step, impedance values ​​at at least two or more frequencies are measured for each battery, in the parallelization impedance calculating step, parallelization impedance values ​​at at least two or more frequencies when a combination of a plurality of batteries is parallelized are calculated, and in the parallelization combination determining step, two or more battery combinations are determined in which the parallelization impedance values ​​at at least two or more frequencies are within a preset allowable range of impedance values. In the method for producing a battery pack of the present invention, it is preferable that in the impedance measuring step, impedance values ​​of each battery are measured for a battery group including at least one used battery.

[0013] Furthermore, the battery pack of the present invention is an assembled battery comprising a parallelization unit in which a plurality of single cells or battery modules are connected in parallel, and a serialization unit in which the parallelization units are connected in series, wherein the parallelization unit is made up of a combination of a plurality of batteries each having a different impedance value, the serialization unit is made up of two or more of the parallelization units connected in series, and the tolerance of the parallelization impedance value of each parallelization unit included in the serialization unit is within 3% of the average value of all parallelization units.

[0014] In the battery pack of the present invention, it is preferable that the tolerance of the parallel impedance value of each parallel unit included in the serial unit at at least two or more frequencies is within 3% of the average value of all parallel units. Also, in the battery pack of the present invention, it is preferable that the parallel unit includes at least one used battery.

[0015] Furthermore, the battery assembly manufacturing support system of the present invention is a support system for manufacturing a battery assembly including a parallelization unit in which a plurality of single cells or battery modules are parallelized, and a serialization unit in which the parallelization unit is serialized, and is characterized by comprising: a storage means for storing individual impedance values ​​obtained for the plurality of single cells or battery modules in association with individual information of the batteries; a parallelization impedance calculation means for selecting any combination of a plurality of batteries each having different impedance values ​​from a group of batteries stored in the storage means, and calculating a parallelization impedance value when the combination of the plurality of batteries is parallelized; a parallelization combination determination means for determining two or more battery combinations in which the parallelization impedance value falls within a preset allowable range of impedance values; and a parallelization combination output means for outputting the battery combinations determined by the parallelization combination determination means.

[0016] In the battery assembly manufacturing support system of the present invention, it is preferable that the storage means stores impedance values ​​at at least two or more frequencies for each battery, the parallelization impedance calculation means calculates parallelization impedance values ​​at at least two or more frequencies when a combination of a plurality of batteries is parallelized, and the parallelization combination determination means determines two or more combinations of batteries whose parallelization impedance values ​​at at least two or more frequencies are within a preset allowable range of impedance values. Also, it is preferable that the battery assembly manufacturing support system of the present invention stores in the storage means the impedance values ​​of each battery obtained for a battery group including at least one used battery in association with individual information of the battery. Effect of the Invention

[0017] According to the present invention, even low-capacity batteries that would conventionally have been discarded can be effectively utilized at low cost without using high-performance control devices or the like. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a flow chart showing a method for producing a battery pack according to the present invention. [Diagram 2] FIG. 2 is an explanatory diagram of the constituent units of a battery, taking an electric vehicle as an example. [Diagram 3] FIG. 3 is an example of an impedance measurement step. [Figure 4] FIG. 4 is an example of the parallel impedance calculation step. [Diagram 5] FIG. 5 shows an example of the parallelization combination determination step. [Figure 6] FIG. 6 shows an example of the battery capacity of a paralleling unit. [Figure 7] FIG. 7 shows an example of the flow from the single cell to the parallelization unit preparation step and the serialization step. [Figure 8] FIG. 8 shows an example of a battery pack manufacturing support system according to the present invention. [Figure 9]FIG. 9 shows the parallel impedance value at 0.1 Hz when two different batteries are combined in this embodiment. [Figure 10] FIG. 10 shows the parallel impedance values ​​at 1 kHz when two different batteries are combined in this embodiment. [Figure 11] FIG. 11 is a diagram showing battery combinations in this embodiment that fall within ±3.0% of both reference values ​​for parallel impedance values ​​at 0.1 Hz and 1 kHz. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] <Manufacturing method of assembled battery> A flowchart of the method for producing a battery pack of the present invention is shown in FIG. As shown in FIG. 1, the manufacturing method of the battery pack of the present invention includes an impedance measuring step (S1), a parallelization impedance calculating step (S2), a parallelization combination determining step (S3), a parallelization unit creating step (S4), and a serialization step (S5). The present invention will be described below based on one embodiment, but the present invention is not limited thereto.

[0020] Impedance measurement steps In the impedance measurement step (S1), the impedance value of each battery is measured for a battery group consisting of a plurality of single cells or battery modules. The battery to be measured is a single cell or a battery module. Examples of the battery include a lithium ion battery, a nickel-metal hydride battery, a lead battery, and a nickel-cadmium battery. The present invention aims to effectively utilize various batteries in different states such as used batteries and defective products shipped, and the batteries used may be new or used. From the viewpoint of effective utilization of used batteries, it is desirable that the battery group to be measured includes at least one used battery, or all of the batteries may be used batteries. A used battery means a single cell or a battery module that has been separated and disassembled after being used for primary use such as an on-board battery of an electric vehicle. Although it is possible to use a primary battery as the battery of the present invention, it is desirable that all of the batteries are secondary batteries in consideration of the usage manner of a storage battery, etc.

[0021] FIG. 2 shows an explanatory diagram of the constituent units of a battery, taking an electric vehicle as an example. An electric vehicle is equipped with a battery pack. Normally, a battery pack is made up of multiple battery modules, and each battery module is made up of multiple single cells. A single cell is the smallest unit of a battery, consisting of one positive electrode, one negative electrode, an electrolyte, etc. Of these, the battery that is the subject of measurement in the present invention is either a single cell or a battery module.

[0022] FIG. 3 shows an example of an impedance measurement step for measuring the impedance of a single battery. In this embodiment, the impedance is measured for 10 types of used single batteries A to J, each of which has a different usage history. The impedance measurement method is not particularly limited, and any known measurement method may be used. The impedance measurement method generally includes, but is not limited to, measurement using an FRA (frequency response analyzer) of an AC sine wave and measurement using the Fourier transform of a DC square wave or step wave. Impedance is generally treated as a complex number Z and expressed as Z=Z'-jZ" divided into real and imaginary components. Impedance Z may also be expressed as an absolute value |Z| and a phase difference φ, such as Z=|Z|cosφ+j|Z|sinφ. In the present invention, Z, Z', and |Z| can be treated as impedance.

[0023] The impedance measurement frequency is not particularly limited, but is usually in the range of 1.0 mHz to 1.0 MHz. Although the measurement point may be one frequency, it is more preferable to obtain impedance values ​​at two or more frequencies. By obtaining impedance values ​​at more frequencies, the state of the batteries when paralleled can be more appropriately matched, and the reliability and safety of the battery pack can be improved. In this embodiment, impedance values ​​Im1, Im2, and Im3 at three frequencies of 0.1, 10, and 1000 Hz are obtained for each cell. Table 1 shows an example of the impedance measurement results.

[0024] [Table 1]

[0025] Parallel impedance calculation steps In the parallelization impedance calculation step (S2), a combination of any number of batteries having different impedance values ​​is selected from the battery group whose impedance values ​​have been measured in the impedance measurement step (S1), and a parallelization impedance value is calculated when the combination of the batteries is parallelized. Note that in this embodiment, since used single batteries with different usage histories are used, the impedance values ​​of the individual batteries vary. Here, for example, the parallelization impedance value when three single batteries A, B, and C are parallelized can be calculated by the following formula 1.

[0026] (Number 1) 1 / Zparallel = 1 / Za + 1 / Zb + 1 / Zc Zparallel: Parallel impedance value when cells A to C are connected in parallel Za: Impedance value of cell A Zb: Impedance value of cell B Zc: Impedance value of cell C

[0027] FIG. 4 shows an example of the parallel impedance calculation step. In this step, first, two cells A and B are selected from the cells A to J, and the parallel impedance values ​​pIm1, pIm2, and pIm3 of each frequency when these two cells are parallelized are calculated. Next, the parallel impedance values ​​of each frequency are calculated in the same manner for any combination of two cells, such as the two cells A and C. Furthermore, the parallel impedance values ​​pIm1, pIm2, and pIm3 of each frequency are calculated in the same manner for combinations of three cells, such as the cells A, B, and C, and the cells A, B, and D. In this way, in the parallel impedance calculation step, various combinations are selected from the cells A to J, their parallel impedance values ​​are calculated, and the numerical values ​​are stored in a database. In this embodiment, the number of cells in parallel is described as two or three, but the number of cells to be combined is not particularly limited and may be two or more. For example, the parallelized impedance may be calculated in a similar manner for four combinations, such as cells A, B, C, D and cells E, F, G, H, or for five combinations, such as cells A, B, C, D, E and cells F, G, H, I, J, and the battery combinations and parallelized impedance values ​​may be stored in a database. Table 2 shows an example of the parallelized impedance calculation results.

[0028] [Table 2]

[0029] Parallelization combination decision step In the parallelization combination determination step (S3), two or more battery combinations are determined such that the parallelization impedance value calculated in the parallelization impedance calculation step (S2) falls within a preset allowable range of impedance values. Here, the present invention parallelizes various types of single cells or battery modules in different states to form parallelized units with uniform impedance values, which are then used as assembled batteries. Since parallelized units with uniform impedance values ​​can be treated as batteries in substantially the same state, two or more of these parallelized units can be serially connected to be used as assembled batteries with various specifications.

[0030] In the parallel combination determination step, for example, based on the parallel impedance values ​​of various combinations of cells such as cells AB, AC, ABC, etc., two or more combinations of cells are selected and determined such that the parallel impedance values ​​fall within a predetermined range. The allowable range of the impedance values ​​is not particularly limited, but it is desirable to set the tolerance from a predetermined reference value within ±3.0%, and more preferably within ±1.5%. As an example, when the preset reference values ​​for the parallel impedance values ​​are α1 (0.1 Hz), α2 (10 Hz), and α3 (1 kHz), the relationship between the parallel impedance values ​​ab1 (0.1 Hz), ab2 (10 Hz), and ab3 (1 kHz) of the combination of cells A and B is as follows: |(α1-ab1) / α1|×100≦3.0% |(α2-ab2) / α2|×100≦3.0% |(α3-ab3) / α3|×100≦3.0% In this case, it can be determined that the parallel impedance value ab1-3 of the combination of the single cells A and B is within the allowable range (within ±3.0%) of the predetermined reference value α1-3.

[0031] When there are a plurality of paralleled units within the allowable range of such a predetermined impedance value, these paralleled units can be treated as batteries in substantially the same state. In the present invention, a battery pack is manufactured by further serializing two or more of such paralleled units. For this reason, in the paralleled combination determination step, it is necessary to select two or more combinations of batteries that fall within the allowable range of the predetermined impedance value. The number of combinations of batteries to be selected may be two or more, and a combination of three or four or more types may be selected and determined as long as the paralleled impedance value falls within the allowable range of the predetermined value. Usually, the output voltage of the battery pack as a whole needs to be adjusted according to the intended use of the battery pack, but in some cases, three or four series or more series may be required in relation to the output voltage of the single cells. For this reason, it is desirable to estimate the number of series connections of the batteries in relation to the output voltage in advance and select the required number of battery combinations. FIG. 5 and Table 3 show an example of the paralleled combination step.

[0032] [Table 3]

[0033] In this embodiment, as an example, three combinations of cells AC, BD, and EFH are selected and determined as combinations that fall within a predetermined allowable range of impedance values. Note that the combinations of cells are not limited to combinations of the same number of cells, and as in this embodiment, combinations of two cells and combinations of three cells may be selected and determined simultaneously as long as the parallel impedance value falls within a predetermined range.

[0034] The battery combination may be determined in the parallel combination determination step using a known combination optimization algorithm, or the calculation of the parallel impedance value in the parallel impedance calculation step and the determination of the battery combination in the parallel combination determination step may be performed by a series of calculation processes.

[0035] In addition, it is desirable that the voltages of the batteries in a combination of parallel batteries are the same. If the voltage difference between the batteries connected in parallel is large, a circulating current will occur from the high-voltage battery to the low-voltage battery, which may cause safety problems. Normally, batteries of the same type can be handled within the same voltage range. Alternatively, the voltages of the batteries can be made uniform by connecting different types of batteries in series. For example, for a lithium-ion battery with a nominal voltage of 3.6V, three nickel-metal hydride batteries with a nominal voltage of 1.2V can be connected in series to form a 3.6V battery, to make the voltages of the batteries uniform.

[0036] In the present invention, by forming a parallel unit by combining a plurality of batteries, it becomes possible to use batteries that had to be discarded in the conventional battery reuse scheme because the capacity of a single battery is too small. By analyzing the impedance value measured in the present invention, parameters that quantify the state of each component, such as electrodes and electrolyte, for estimating battery capacity can be obtained. For the sake of simplicity, taking battery capacity as an example, when the remaining capacity decreases due to the progression of deterioration, the impedance value at a specific frequency increases. For this reason, making the impedance value of the parallel unit uniform is equivalent to making the battery capacity of the parallel unit uniform. FIG. 6 shows an example of the battery capacity of the parallel unit. It is assumed that the total battery capacity of the parallel unit in this embodiment is 100%, and that the combination of unit cells AC is A50%, C50%, the combination of unit cells BD is B80%, D20%, and the combination of unit cells EFH is E50%, F30%, and H20% (note that the actual combination of the capacity of each unit cell when the parallel impedance is uniform may be different). In this case, when looking at each individual cell, cells D, F, and H with a capacity of 30% or less have too little remaining capacity and must be discarded under conventional battery reuse schemes. In contrast, the present invention uses these small-capacity batteries as parallel units and uses them together with other batteries, making it possible to effectively utilize the batteries to the end without having to discard them.

[0037] Furthermore, by analyzing the impedance value measured in the present invention, parameters that quantify the state of each component, such as the electrodes, electrolyte, etc., can be obtained. Therefore, even if the remaining capacity is sufficient, it is possible to avoid using a battery that has safety issues, and the battery can be used as a safer assembled battery.

[0038] Next, a battery pack is manufactured by parallelizing and serializing the unit cells based on the combination of cells determined in the parallelization combination determination step. Fig. 7 shows an example of the flow from the unit cells to the parallelization unit creation step and the serialization step.

[0039] Parallelization unit creation steps In the paralleling unit creation step (S4), the cells are parallelized based on the combination of cells determined in the paralleling combination determination step (S3). In this embodiment, the three combinations of cells AC, BD, and EFH selected in the paralleling combination determination step are connected in parallel to create three paralleling units.

[0040] Serialization Step In the serialization step (S5), two or more parallelized units created in the parallelized unit creation step (S4) are connected in series to form a final battery pack. Here, the impedance value of each parallelized unit is within a preset allowable range of impedance values ​​as the battery combination selected and determined in the parallelization combination determination step. In this embodiment, three types of parallelized units, namely, the single cells AC, BD, and EFH, parallelized in the parallelization step, are connected in series to manufacture a battery pack. Here, when batteries are normally connected in series, if a plurality of batteries with different capacities are connected in series, the battery with the smaller capacity is overcharged or overdischarged, and the battery cannot be used safely. In contrast, in the present invention, parallelized units with the same impedance value are connected in series, so the battery capacities of the parallelized units are equivalent, and in a battery pack manufactured by serializing them, the remaining capacity of each parallelized unit can be safely and efficiently utilized.

[0041] Here, the paralleling impedance values ​​of the paralleling units consisting of the cells AC, BD, and EFH are all within the allowable range of the reference impedance value, and it is further desirable that the paralleling impedance values ​​of these individual paralleling units have a tolerance of 3.0% or less from the average value of all paralleling units. Even if the impedance values ​​are within the allowable range of the reference impedance value, if there is a biased deviation from the reference value, the difference in impedance values ​​between the paralleling units as a whole will be large, and there is a possibility that they will not be able to be used appropriately.

[0042] For example, if the tolerances of the parallel impedance values ​​of the cells AC, BC, and EFH from the reference value are assumed to be +2.5%, -2.5%, and -2.5%, respectively, each parallel unit is within the tolerance range from the reference value, but there is a difference of 5% between the cell AC and the cells BC and EFH, and the overall value is biased toward the negative side from the reference value. Therefore, it is desirable to combine parallel units so that the parallel impedance values ​​of each parallel unit are within a tolerance of 3% from the average value of all parallel units. As an example, if the average values ​​of the three parallel impedance values ​​of the cells AC, BC, and EFH are Av1 (0.1 Hz), Av2 (10 Hz), and Av3 (1 kHz), the relationship between the parallel impedance values ​​ab1 (Hz), ab2 (Hz), and ab3 (Hz) of the combination of cells A and B is as follows: |(Av1-ab1) / Av1|×100≦3.0% |(Av2-ab2) / Av2|×100≦3.0% |(Av3-ab3) / Av3|×100≦3.0% In this case, the parallel impedance value ab1-3 of the parallel unit of the cells AB falls within a tolerance of 3.0% with respect to the average value Av1-3 of the entire parallel unit.

[0043] The assembled battery thus manufactured is a battery in which two or more parallel units, each of which is a combination of a plurality of batteries with different impedance values, are connected in series, and the tolerance of the parallel impedance value of each parallel unit included in the serial unit is within 3.0% of the average value of all parallel units. Such an assembled battery also falls within the scope of the present invention.

[0044] <Battery assembly manufacturing support system> Furthermore, the impedance values ​​of the individual batteries measured in the impedance measuring step of the present invention are stored in a storage means, a series of arithmetic processes are performed in a parallelization impedance calculating step and a parallelization combination determining step, and an appropriate combination of batteries is output, thereby making it possible to provide a support system for manufacturing an assembled battery by subsequent parallelization and serialization. Fig. 8 shows an example of the assembled battery manufacturing support system of the present invention. As shown in Fig. 8, the manufacturing support system 100 of the present invention includes a storage means 110, a parallelization impedance calculating means 120, a parallelization combination determining means 130, and a parallelization combination output means 140.

[0045] The storage means 110 stores the individual impedance values ​​acquired for the multiple cells or battery modules in association with the individual battery information. The individual battery information may be identification information attached to each battery during its manufacture. Alternatively, prior to measuring the battery impedance, a two-dimensional barcode may be attached to each cell or battery module, making each battery identifiable.

[0046] The parallelization impedance calculation means 120 selects any combination of a plurality of batteries each having a different impedance value based on the impedance value information stored in the storage means 110, and calculates a parallelization impedance value when the combination of batteries is parallelized. Furthermore, the parallelization combination determination means 130 determines two or more combinations of batteries whose parallelization impedance value falls within a preset allowable range of impedance values ​​based on the parallelization impedance value of any combination of batteries obtained by the parallelization impedance calculation means 120. Note that this series of calculation processes is similar to the parallelization impedance calculation step and parallelization combination determination step described above.

[0047] Next, the parallelization combination output means 140 outputs the battery combination determined by the parallelization combination determination means 130 to the outside. The output information is output as battery combination information based on the individual battery information stored in the storage means 110. As an output method, for example, the battery combination information may be displayed on a separately provided display means such as a display, or the battery combination information may be transmitted to an external device with which communication is possible.

[0048] In the manufacturing support system 100 of this embodiment, the storage means 110, the parallelization impedance calculation means 120, the parallelization combination determination means 130, and the output means 140 are integrated into a PC. The PC is equipped with a CPU, a ROM, a RAM, an external storage device, and the like, which allow the storage means 110, the parallelization impedance calculation means 120, the parallelization combination determination means 130, and the output means 140 to perform the above-mentioned respective functions. Therefore, by inputting individual information and impedance values ​​of each battery to the PC of the manufacturing support system 100, appropriate battery combination information is output after a series of calculation processes. A manufacturer of assembled batteries can easily manufacture assembled batteries by parallelizing and serializing batteries according to this battery combination information.

[0049] In the manufacturing support system 100 of this embodiment, all the means are integrated into one PC, but the storage means may be provided in a separate external server or the like in a state capable of communicating with other means. The parallelization impedance values ​​calculated by the parallelization impedance calculation means may be temporarily stored in the storage means, and as soon as the specifications of the battery pack required are determined, the parallelization impedance value data may be called up and the parallelization combination determination means may perform arithmetic processing. In addition, for example, when the storage locations of the individual batteries are different, the storage means may store information on the storage locations as individual information of the batteries, and the parallelization combination determination means may specify and combine batteries that are stored in the same or nearby storage locations. EXAMPLES

[0050] In order to confirm the effect of improving the usability of the batteries by creating a parallelization unit, the inventors performed the following simulation calculations based on the impedance measurement results of batteries in different states of deterioration. (1) Impedance (Z') plots at 0.1H and 1kHz were created based on the impedance measurement results of several batteries with different deterioration states. (2) Based on the impedance values ​​of each battery at 0.1 Hz and 1 kHz, the parallel impedance value when two different batteries are combined was calculated. The results are shown in Figures 9 and 10 (Figure 9: 0.1 Hz, Figure 10: 1 kHz). (3) The standard values ​​for the paralleled impedance value at 0.1 Hz were set to 8.333 Ω, and the standard values ​​for the paralleled impedance value at 1 kHz were set to 3.472 Ω, and battery combinations that fell within ±3.0% of both standard values ​​were investigated. The results are shown in Figure 11. Battery combinations that fell within the same range are indicated by a ◆.

[0051] As shown in Fig. 11, the battery combinations indicated by ◆ have the same parallel impedance values ​​at 0.1 Hz and 1 kHz, and the paralleled units of these combinations can be treated as batteries in substantially the same state. Therefore, by selecting any combination of batteries from the battery combinations indicated by ◆ to make a paralleled unit and then serializing this, it is possible to make battery packs with various specifications. Note that in this embodiment, the paralleled connection of two batteries was simulated, but when three or more batteries are paralleled, the range of available battery combinations is further expanded.

[0052] In conventional reuse schemes for used batteries, batteries with the same conditions, such as battery capacity, are combined to reconstruct the batteries, and the combinations of reusable batteries are very limited. In contrast, in the method of the present invention, batteries with different conditions are combined so that the parallel impedance values ​​are equal, and the batteries can be treated as batteries with the same condition, so that used batteries with various different conditions can be efficiently used. In addition, low-capacity used batteries that had to be discarded in conventional reuse schemes can be efficiently reused by combining them with other used batteries in parallel. [Explanation of symbols]

[0053] 100 Battery assembly manufacturing support system 110 Memory means 120 Parallel impedance calculation method 130 Parallelization combination decision method 140 Parallel combination output means

Claims

1. an impedance measuring step of measuring an impedance value of each battery of a battery group consisting of a plurality of single cells or battery modules; a parallelization impedance calculation step of selecting any combination of a plurality of batteries each having a different impedance value from the battery group whose impedance values ​​have been measured in the above step, and calculating a parallelization impedance value when the combination of the plurality of batteries is parallelized; a parallelization combination determination step of determining two or more combinations of batteries in which the parallelization impedance value falls within a preset allowable range of impedance values; a parallelization unit creation step of parallelizing two or more of the battery combinations determined in the above step; a serialization step of serializing two or more parallelized units created by the above step; A manufacturing method of a battery pack comprising:

2. In the impedance measuring step, impedance values ​​are measured at least at two or more frequencies for each battery; In the parallelization impedance calculation step, a parallelization impedance value is calculated at at least two or more frequencies when a combination of a plurality of batteries is parallelized; In the parallel connection combination determination step, two or more battery combinations are determined such that the parallel connection impedance value at at least two or more frequencies falls within a preset allowable range of impedance values. The method for manufacturing a battery pack according to claim 1 .

3. In the impedance measuring step, the impedance value of each battery is measured for a battery group including at least one used battery. The method for manufacturing a battery pack according to claim 1 .

4. A battery pack including a parallelization unit in which a plurality of single cells or battery modules are connected in parallel, and a serialization unit in which the parallelization units are connected in series, the parallelization unit is composed of a combination of a plurality of batteries each having a different impedance value; the serialization unit is formed by serializing two or more of the parallelization units, The tolerance of the parallel impedance value of each parallel unit included in the serial unit is within 3% of the average value of all parallel units. A battery pack comprising:

5. 5. The battery pack according to claim 4, wherein a tolerance of parallel impedance values ​​of each of the parallel units included in the serial unit at at least two frequencies is within 3% of an average value of all the parallel units.

6. 5. The battery pack according to claim 4, wherein the paralleling unit includes at least one used battery.

7. A support system for manufacturing a battery pack including paralleling units in which a plurality of single cells or battery modules are parallelized, and a serialization unit in which the paralleling units are serialized, comprising: a storage means for storing the impedance values ​​of the individual batteries obtained for a battery group consisting of a plurality of single cells or battery modules in association with individual information of the battery; a parallelization impedance calculation means for selecting any combination of a plurality of batteries each having a different impedance value from the battery group stored in the storage means, and calculating a parallelization impedance value when the combination of the plurality of batteries is parallelized; a parallelization combination determination means for determining two or more combinations of batteries such that the parallelization impedance value falls within a preset allowable range of impedance values; a parallelization combination output means for outputting the combination of batteries determined by the parallelization combination determination means; A battery pack manufacturing support system comprising:

8. The storage means stores impedance values ​​at at least two or more frequencies for each battery, the parallelization impedance calculation means calculates parallelization impedance values ​​at at least two or more frequencies when a combination of a plurality of batteries is parallelized; The parallel connection combination determining means determines two or more battery combinations in which the parallel connection impedance value at at least two or more frequencies falls within a preset allowable range of impedance values.

8. The battery pack manufacturing support system according to claim 7.

9. In the storage means, the impedance value of each battery acquired for the battery group including at least one used battery is stored in association with individual information of the battery.

8. The battery pack manufacturing support system according to claim 7.

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