Evaluation method for lithium ion secondary battery, manufacturing method of battery unit, evaluation device and manufacturing support device

Abstract

To provide an evaluation method for a lithium ion secondary battery capable of accurately evaluating high rate deterioration characteristics of a lithium ion secondary battery, a manufacturing method of a battery unit, an evaluation device and a manufacturing support device.SOLUTION: An evaluation method for a lithium ion secondary battery includes the steps of: acquiring manufacture data of a cathode and an anode constituting an electrode body of a lithium ion secondary battery; estimating liquid flow amounts of an electrolyte in the cathode and the anode from the manufacture data of the cathode and the anode; calculating a liquid flow ratio of the electrode body from the estimated liquid flow amount of the cathode and the estimated liquid flow amount of the anode; and predicting high rate deterioration characteristics of the lithium ion secondary battery on the basis of the calculated liquid flow ratio.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to a lithium ion secondary battery evaluation method, a battery unit manufacturing method, an evaluation device, and a manufacturing support device. [Background technology]

[0002] It is known that in lithium ion secondary batteries, repeated charging and discharging at a large current (hereinafter also referred to as "high-rate charging and discharging") leads to a local increase in internal resistance. This increase in internal resistance is believed to occur through the following mechanism. First, the volume of the electrode body changes due to high-rate charging and discharging. This change in the volume of the electrode body causes a flow of electrolyte, such as outflow of electrolyte from the electrode body and re-inflow of electrolyte into the electrode body. This flow of electrolyte causes a bias in the salt concentration inside the electrode body, resulting in a local increase in internal resistance. Note that such an increase in internal resistance can be eliminated, for example, if the above-mentioned bias in salt concentration is improved over time.

[0003] The increase in internal resistance leads to a temporary decrease in battery performance (hereinafter also referred to as "high-rate degradation"). For this reason, various methods have been proposed for suppressing the increase in internal resistance (for example, see Patent Document 1 below).

[0004] Patent Document 1 listed below discloses a lithium ion secondary battery including a negative electrode mixture layer, a positive electrode mixture layer facing the negative electrode mixture layer with a separator sandwiched therebetween, and an electrolyte, in which the negative electrode mixture layer contains 3% by mass to 7% by mass of hollow silica particles, the hollow silica particles have an average particle diameter of 50 nm to 110 nm, and the negative electrode mixture layer has an average pore diameter of 1.0 to 1.83 times the average pore diameter of the positive electrode mixture layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-66461 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described in Patent Document 1, high-rate degradation can be suppressed by devising the material of the electrode body during the manufacture of the lithium-ion secondary battery. However, it is difficult to implement the above-mentioned devising of the material of the electrode body for a lithium-ion secondary battery that has already been manufactured.

[0007] For example, a lithium ion secondary battery with good high-rate degradation characteristics can obtain stable output even when used in applications where high-rate charging and discharging are frequently performed or in areas with high environmental temperatures. In contrast, when a lithium ion secondary battery with poor high-rate degradation characteristics is used in applications where high-rate charging and discharging are frequently performed or in areas with high environmental temperatures, high-rate degradation occurs frequently, and problems such as unstable output and a shortened battery life associated with this are likely to occur.

[0008] On the other hand, even if a lithium-ion secondary battery does not have good high-rate degradation characteristics, high-rate degradation is unlikely to occur and problems such as output instability are relatively unlikely to occur if the battery is used in applications where high-rate charging and discharging is not frequent or in areas where the environmental temperature is relatively low. For this reason, even with lithium-ion secondary batteries after manufacture, the occurrence of the above-mentioned various problems may be suppressed if the battery is used in applications that match its performance. In order to realize use in applications that match the above-mentioned performance, it is important to accurately evaluate the performance of the lithium-ion secondary battery, particularly the high-rate degradation characteristics.

[0009] In consideration of the above, the present disclosure aims to provide a lithium ion secondary battery evaluation method, a battery unit manufacturing method, an evaluation device, and a manufacturing support device that are capable of accurately evaluating the high-rate degradation characteristics of a lithium ion secondary battery. [Means for solving the problem]

[0010] In order to achieve the above object, a method for evaluating a lithium ion secondary battery according to a first aspect of the present disclosure includes the steps of acquiring manufacturing data of a positive electrode and a negative electrode that constitute an electrode body of a lithium ion secondary battery, estimating a liquid flow rate of an electrolyte in the positive electrode and the negative electrode from the manufacturing data of the positive electrode and the negative electrode, calculating a liquid flow ratio of the electrode body from the estimated liquid flow rate of the positive electrode and the estimated liquid flow rate of the negative electrode, and predicting high-rate degradation characteristics of the lithium ion secondary battery based on the calculated liquid flow ratio.

[0011] In such a method for evaluating a lithium ion secondary battery, the high-rate degradation characteristics of the lithium ion secondary battery can be accurately predicted, and thus the use of the lithium ion secondary battery can be determined in consideration of the high-rate degradation characteristics, thereby suppressing the occurrence of high-rate degradation of the lithium ion secondary battery.

[0012] A method for evaluating a lithium ion secondary battery according to a second aspect of the present disclosure is the method for evaluating a lithium ion secondary battery according to the above-mentioned first aspect, wherein the step of estimating the liquid flow volume estimates the liquid flow volume using a multiple regression equation in which the liquid flow volume of the positive electrode or the negative electrode is a response variable and the production data of the positive electrode or the negative electrode is an explanatory variable.

[0013] In such a method for evaluating a lithium ion secondary battery, the amount of liquid flow in the positive electrode and the negative electrode can be estimated with high accuracy.

[0014] A method for evaluating a lithium-ion secondary battery according to a third aspect of the present disclosure is the method for evaluating a lithium-ion secondary battery according to the above-mentioned second aspect, wherein the manufacturing data of the positive electrode includes at least one of a particle shape of a positive electrode active material contained in the positive electrode, a basis weight of a positive electrode paste, and a density of each material in the positive electrode paste.

[0015] In such a method for evaluating a lithium ion secondary battery, the amount of liquid flow in the positive electrode can be estimated with higher accuracy.

[0016] A method for evaluating a lithium ion secondary battery according to a fourth aspect of the present disclosure is the method for evaluating a lithium ion secondary battery according to the second or third aspect, wherein the manufacturing data of the negative electrode includes at least one of an average particle size of a negative electrode active material contained in the negative electrode and an application amount of a negative electrode paste.

[0017] In such a method for evaluating a lithium ion secondary battery, the amount of liquid flow in the negative electrode can be estimated with higher accuracy.

[0018] A lithium ion secondary battery evaluation method according to a fifth aspect of the present disclosure is the lithium ion secondary battery evaluation method according to any one of the first to fourth aspects, further comprising a step of identifying an appropriate range of conditions related to deterioration of the environment in which the lithium ion secondary battery is used, based on the predicted high-rate deterioration characteristics of the lithium ion secondary battery.

[0019] In such a method for evaluating a lithium ion secondary battery, the intended use and the like can be selected in consideration of the appropriate range of deterioration conditions for each lithium ion secondary battery.

[0020] A lithium ion secondary battery evaluation method according to a sixth aspect of the present disclosure is the lithium ion secondary battery evaluation method according to any one of the first to fifth aspects, further comprising a step of identifying an appropriate temperature range of the environment in which the lithium ion secondary battery is used, based on the predicted high-rate degradation characteristics of the lithium ion secondary battery.

[0021] In such a method for evaluating a lithium ion secondary battery, it is possible to realize use at an optimal environmental temperature for each lithium ion secondary battery.

[0022] A manufacturing method of a battery unit according to a seventh aspect of the present disclosure is a manufacturing method of a battery unit in which a plurality of lithium ion secondary batteries are connected, and includes the steps of acquiring manufacturing data of positive electrodes and negative electrodes constituting each electrode body of the plurality of lithium ion secondary batteries, estimating a liquid flow rate of an electrolyte in the positive electrode and the negative electrode from the manufacturing data of the positive electrode and the negative electrode, calculating a liquid flow ratio of the electrode body from the estimated liquid flow rate of the positive electrode and the estimated liquid flow rate of the negative electrode, predicting high-rate deterioration characteristics of each of the plurality of lithium ion secondary batteries based on the calculated liquid flow ratio, determining an order for connecting the lithium ion secondary batteries based on the high-rate deterioration characteristics of each of the plurality of lithium ion secondary batteries and environmental information of a position where the battery unit is installed, and connecting the plurality of lithium ion secondary batteries in the determined order.

[0023] In such a method for manufacturing a battery unit, by devising an appropriate arrangement of the lithium ion secondary batteries, it is possible to provide a battery unit in which the occurrence of high-rate degradation is suppressed.

[0024] A manufacturing method of a battery unit according to an eighth aspect of the present disclosure is the manufacturing method of a battery unit according to the seventh aspect, wherein the environmental information includes temperature information of a position where the battery unit is installed.

[0025] In such a method for manufacturing a battery unit, for example, by arranging lithium ion secondary batteries, which are less susceptible to high-rate degradation, in an area that becomes relatively hot, it is possible to suppress deterioration in the performance of the battery unit.

[0026] An evaluation device according to a ninth aspect of the present disclosure includes an acquisition unit capable of acquiring manufacturing data of a positive electrode and a negative electrode that constitute an electrode body of a lithium ion secondary battery, an estimation unit capable of estimating a liquid flow volume of an electrolyte in the positive electrode and the negative electrode from the manufacturing data of the positive electrode and the negative electrode, a calculation unit capable of calculating a liquid flow ratio of the electrode body from the estimated liquid flow volume of the positive electrode and the estimated liquid flow volume of the negative electrode, and a characteristic prediction unit capable of predicting high-rate degradation characteristics of the lithium ion secondary battery based on the calculated liquid flow ratio.

[0027] Such an evaluation device can accurately predict the high-rate degradation characteristics of a lithium-ion secondary battery, which allows the use of the lithium-ion secondary battery to be determined in consideration of the high-rate degradation characteristics, thereby suppressing the occurrence of high-rate degradation of the lithium-ion secondary battery.

[0028] A manufacturing support device according to a tenth aspect of the present disclosure is a manufacturing support device that supports the manufacturing of a battery unit in which a plurality of lithium ion secondary batteries are connected, and includes: an acquisition unit capable of acquiring manufacturing data of positive and negative electrodes that constitute each electrode body of the plurality of lithium ion secondary batteries and environmental information of a position where the battery unit is installed; an estimation unit capable of estimating a liquid flow rate of the electrolyte in the positive electrode and the negative electrode from the manufacturing data of the positive electrode and the negative electrode; a calculation unit capable of calculating a liquid flow ratio of the electrode body from the estimated liquid flow rate of the positive electrode and the estimated liquid flow rate of the negative electrode; a characteristic prediction unit capable of predicting high-rate deterioration characteristics of each of the plurality of lithium ion secondary batteries based on the calculated liquid flow ratio; and an order determination unit that determines the order in which the lithium ion secondary batteries are connected based on the high-rate deterioration characteristics of each of the plurality of lithium ion secondary batteries and the environmental information.

[0029] In such a manufacturing support device, by devising an appropriate arrangement of each lithium ion secondary battery, it is possible to support the manufacturing of a battery unit in which the occurrence of high-rate degradation is suppressed. Effect of the Invention

[0030] According to the present disclosure, it is possible to provide a method for evaluating the high-rate degradation characteristics of a lithium-ion secondary battery, a method for manufacturing a battery unit, an evaluation device, and a manufacturing support device, which can promote the use of each lithium-ion secondary battery in an appropriate form according to its performance. [Brief description of the drawings]

[0031] [Figure 1] 1 is a perspective view showing an example of a configuration of a lithium-ion secondary battery to be evaluated in a method for evaluating a lithium-ion secondary battery according to an embodiment of the present disclosure. [Diagram 2] 2 is a schematic diagram showing an example of the configuration of an electrode body of the lithium ion secondary battery shown in FIG. [Diagram 3] 2 is a flowchart showing an example of a method for manufacturing the lithium ion secondary battery shown in FIG. [Figure 4] FIG. 2 is a schematic diagram for explaining an example of a method for measuring the amount of liquid flow in an electrode body of the lithium ion secondary battery shown in FIG. [Diagram 5] 2 is a graph showing the correlation between the estimated and actually measured values ​​of the liquid flow rate of the electrode body of the lithium ion secondary battery shown in FIG. 1. [Figure 6] 1 is a graph showing the relationship between the liquid flow ratio and the high-rate resistance change rate. [Figure 7] 1 is a block diagram showing an example of a hardware configuration of an evaluation device according to an embodiment of the present disclosure. [Figure 8] 8 is a functional block diagram showing an example of a functional configuration of a control unit of the evaluation device shown in FIG. 7. [Figure 9] 1 is a flowchart illustrating an example of a method for evaluating a lithium-ion secondary battery according to an embodiment of the present disclosure. [Figure 10] 1 is a schematic plan view showing an example of a battery unit manufactured by a battery unit manufacturing method according to an embodiment of the present disclosure. [Figure 11] 11 is a graph showing an example of temperature distribution at a position where the battery unit shown in FIG. 10 is installed. [Figure 12] 2 is a functional block diagram showing an example of a functional configuration of a control unit of a manufacturing support device according to an embodiment of the present disclosure. FIG. [Figure 13] 4 is a flowchart illustrating an example of a manufacturing method of a battery unit according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, each embodiment for carrying out the present disclosure will be described with reference to the drawings. Note that, below, the scope necessary for the explanation to achieve the object of the present disclosure is shown in a schematic manner, and the scope necessary for the explanation of the relevant part of the present disclosure will be mainly explained, and the parts that are omitted from the explanation will be based on the publicly known technology.

[0033] Before describing the evaluation method of the lithium ion secondary battery according to the present embodiment, a brief description will be given of the lithium ion secondary battery to be evaluated in the present embodiment and a method for manufacturing the same.

[0034] Fig. 1 is a perspective view showing an example of the configuration of a lithium-ion secondary battery to be evaluated in the method for evaluating a lithium-ion secondary battery according to an embodiment of the present disclosure. As the lithium-ion secondary battery 10 whose performance is evaluated in the method for evaluating a lithium-ion secondary battery according to the present embodiment, for example, a flat prismatic cell battery can be used, as shown in Fig. 1. The specific shape of the lithium-ion secondary battery 10 is not particularly limited, and the battery may have a shape other than a flat prismatic shape.

[0035] 1, the lithium ion secondary battery 10 may include a rectangular battery case 20 that is open on the upper side, and a lid body 30. The battery case 20 and the lid body 30 may be made of materials such as aluminum or an aluminum alloy.

[0036] The battery case 20 can be configured as a box-shaped member having a space inside. A wound electrode body 40 and an electrolyte 22 can be accommodated inside the battery case 20. The lid 30 closes the opening of the battery case 20 and can be joined to the battery case 20 by welding or the like.

[0037] Fig. 2 is a schematic diagram showing an example of the configuration of the electrode body of the lithium ion secondary battery shown in Fig. 1. As shown in Fig. 2, the electrode body 40 housed in the battery case 29 can be composed of an electrode plate group including a positive electrode plate 42 as an example of a positive electrode, a negative electrode plate 44 as an example of a negative electrode, and a separator 46. Each of the positive electrode plate 42, the negative electrode plate 44, and the separator 46 can be composed of a long sheet member. In the following, the positive electrode plate 42 and the negative electrode plate 44 may be collectively referred to as electrode plates.

[0038] The positive electrode plate 42 may include a positive electrode current collector 42A and a positive electrode active material layer 42B formed on one or both sides of the positive electrode current collector 42A except for the ends. The negative electrode plate 44 may include a negative electrode current collector 44A and a negative electrode active material layer 44B formed on one or both sides of the negative electrode current collector 44A except for the ends. The materials of the electrolyte 22, the positive electrode plate 42, the negative electrode plate 44, and the separator 46 will be described later.

[0039] The positive electrode plate 42 and the negative electrode plate 44 may be stacked with a separator 46 interposed therebetween and wound along the longitudinal direction of each. The positive electrode current collector 42A (i.e., the portion where the positive electrode active material layer 42B is not formed) is exposed at one end of the electrode body 40 in the winding axis direction perpendicular to the winding direction. The negative electrode current collector 44A (i.e., the portion where the negative electrode active material layer 44B is not formed) is exposed at the other end of the electrode body 40 in the winding axis direction.

[0040] The lid 30 may be provided with a positive terminal 32P and a negative terminal 32N used for charging and discharging power. The positive terminal 32P may be joined to a positive current collector 38P, and the positive current collector 38P may be joined to a positive current collector 42A of the positive plate 42. The negative terminal 32N may be joined to a negative current collector 38N, and the negative current collector 38N may be joined to a negative current collector 44A of the negative plate 44. The lid 30 may be provided with a safety valve 34 that opens when the internal pressure of the battery exceeds a predetermined pressure, and a liquid injection port 36 for injecting an electrolyte. The positive terminal 32P, the negative terminal 32N, the positive current collector 38P, and the negative current collector 38N may be made of aluminum, an aluminum alloy, or the like.

[0041] The positive electrode current collector 42A of the positive electrode plate 42 may be, for example, an aluminum foil. The positive electrode active material layer 42B may include, for example, a positive electrode active material, a conductive material, and a binder. For the positive electrode active material, for example, a ternary (nickel (N), manganese (M), cobalt (C))-based positive electrode material may be adopted. More specifically, lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2), etc. may be used. For example, acetylene black (AB) etc. may be used as the conductive material. For example, polyvinylidene fluoride (PVDF) etc. may be used as the binder.

[0042] The negative electrode current collector 44A of the negative electrode plate 44 may be, for example, a copper foil. The negative electrode active material layer 44B may contain, for example, a negative electrode active material, a binder, and a thickener. For example, a carbon-based material may be used as the negative electrode active material. More specifically, a powdered carbon material made of graphite or the like may be used. For example, styrene butadiene rubber (SBR) or the like may be used as the binder. For example, sodium carboxymethyl cellulose (CMC) may be used as the thickener.

[0043] The electrolyte 22 is a solution in which a supporting salt is contained in a non-aqueous solvent. As the non-aqueous solvent, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc. can be used. As the supporting salt, lithium salts such as LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiC4F9SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, LiI, etc. can be used.

[0044] The separator 46 can be made of a porous insulating film that insulates the positive electrode plate 42 from the negative electrode plate 44 and allows the electrolyte 22 to pass through. As the separator 46, a porous polyolefin film such as a porous polyethylene film or a porous polypropylene film can be used.

[0045] An example of a method for manufacturing a lithium ion secondary battery will be described below mainly with reference to FIG.

[0046] Fig. 3 is a flow chart showing an example of a method for manufacturing the lithium ion secondary battery shown in Fig. 1. When manufacturing a lithium ion secondary battery, first, a positive electrode material and a negative electrode material are prepared as shown in Fig. 3 (step S10). When preparing the positive electrode material and the negative electrode material, it is advisable to record the physical property data of the positive electrode material and the negative electrode material (more specifically, the particle shape and average particle size of the substance, etc.) as part of the manufacturing data described later. In this embodiment, a ternary positive electrode material (NMC) is used as the positive electrode material, and a carbon-based material is used as the negative electrode material.

[0047] Next, a kneading step is performed (step S12). In this kneading step, the active material, conductive material, binder, etc. are mixed for the positive electrode material and the negative electrode material to prepare a positive electrode paste and a negative electrode paste, respectively. Such a mixture is also called a "composite material." In addition, it is advisable to record the basis weight, application amount, etc. of each of the prepared pastes as part of the manufacturing data described later.

[0048] After the kneading step is completed, a coating step is performed (step S14). In this coating step, the positive electrode paste is applied to one or both sides of a positive electrode current collector 42A made of aluminum foil and dried to form a positive electrode active material layer 42B. This allows the positive electrode plate 42 to be obtained. Similarly, the negative electrode paste is applied to one or both sides of a negative electrode current collector 44A made of copper foil and dried to form a negative electrode active material layer 44B. This allows the negative electrode plate 44 to be obtained.

[0049] Next, a pressing step is performed on each of the obtained positive electrode plate 42 and negative electrode plate 44 (step S16). In the pressing step, each of the positive electrode plate 42 and negative electrode plate 44 is pressed to adjust the thickness to a predetermined value. After the pressing step is performed, the positive electrode plate 42 and negative electrode plate 44 are cut to a predetermined size.

[0050] When the plurality of positive electrode plates 42 and negative electrode plates 44 cut to a predetermined size are obtained, an electrode pair determination step is then performed (step S18). In the electrode pair determination step, the positive electrode plates 42 and negative electrode plates 44 manufactured in a plurality of production lots are paired in pairs to form the electrode body 40.

[0051] Once the pair of positive electrode plates 42 and negative electrode plates 44 has been determined, an electrode body forming process is then performed (process S20). In the electrode body forming process, the positive electrode plates 42 and negative electrode plates 44, which have been cut to a predetermined size, are alternately stacked with separators 46 interposed therebetween to form the electrode body 40. At this time, the positive electrode plates 42, negative electrode plates 44, and separators 46 are pressed against each other and shaped into a desired shape.

[0052] Once the electrode body 40 is formed, a cell assembly process is then performed (step S22). In the cell assembly process, a battery cell is assembled as follows. First, the positive current collector 38P is welded to the positive current collector 42A of the electrode body 40, and the negative current collector 38N is welded to the negative current collector 44A. Next, the electrode body 40 to which the positive current collector 38P and the negative current collector 38N are attached is housed in the battery case 20. The battery case 20 and the lid 30 are joined by welding. At this stage, the liquid inlet 36 of the lid 30 is still open.

[0053] Next, a cell drying step is performed (step S24). In this cell drying step, moisture is removed from the electrode body 40 by heating or the like. Then, an electrolyte injection / hermetically sealing step is performed (step S26). In this step, the electrolyte 22 is filled into the battery case 20, and then the injection port 36 is hermetically sealed. This results in a lithium ion secondary battery 10.

[0054] Once the lithium ion secondary battery 10 is obtained, an activation process is then performed (step S28). In the activation process, the lithium ion secondary battery 10 is initially charged, and then a high-temperature aging process is performed in which the battery is stored at a high temperature for a certain period of time. Finally, an inspection process is performed (step S30). In the inspection process, various inspections are performed on the lithium ion secondary battery 10, and the series of manufacturing processes is completed.

[0055] The method for evaluating a lithium-ion secondary battery according to the present embodiment evaluates the performance of the lithium-ion secondary battery 10 manufactured through the series of manufacturing steps described above. More specifically, the method evaluates the high-rate degradation characteristics of the lithium-ion secondary battery 10 to identify suitable uses, etc., of the lithium-ion secondary battery 10.

[0056] In light of the above, in this embodiment, the liquid flow amount of the positive electrode plate 42 and the negative electrode plate 44 is estimated in order to predict the high-rate deterioration characteristics of the lithium-ion secondary battery 10. Here, the liquid flow amount is an index representing the amount of electrolyte flow including the outflow of the electrolyte from the electrode body and the inflow of the electrolyte into the electrode body. In other words, the liquid flow amount can be said to be an index showing the ease of flow of the electrolyte in the positive electrode plate 42 and the negative electrode plate 44.

[0057] FIG. 4 is a schematic diagram for explaining an example of a method for measuring the amount of liquid flow in the electrode body of the lithium ion secondary battery shown in FIG. 1. The actual value of the amount of liquid flow can be measured, for example, as follows. First, as shown in FIG. 4(A), an electrode plate (here, the positive electrode plate 42) and a separator 46 are wound around a cylindrical winding core 52 to prepare a measurement sample 50. At this time, the open end of the winding core 52 is blocked with a rubber plug 56. Next, as shown in FIG. 4(B), the measurement sample 50 is housed in a measurement case 54. At this time, an O-ring 58 is used to prevent electrolyte leakage from the gap between the measurement sample 50 and the measurement case 54.

[0058] Next, the electrolyte is injected into the measurement case 54, and the measurement sample 50 is impregnated with the electrolyte. After the impregnation, a predetermined pressure is applied, and the amount of electrolyte flowing out of the measurement sample 50 per unit time is measured. The pressure value is changed in various ways, and the amount of electrolyte flowing out per unit time is measured. Then, a straight line that represents the amount of electrolyte flowing out per unit time against the pressure is obtained, and the slope of this straight line is defined as the "liquid flow amount." The unit of the liquid flow amount obtained by this method is, for example, "g / kPa."

[0059] In the evaluation method of the lithium ion secondary battery according to the present embodiment, the liquid flow amount of the lithium ion secondary battery 10 after manufacture is estimated, so the above-mentioned actual measurement method cannot be adopted. Therefore, in the present embodiment, an estimated value of the liquid flow amount is obtained. Hereinafter, the actual measured value of the liquid flow amount is expressed as "liquid flow amount (actual measured value)", and the estimated value of the liquid flow amount is expressed as "liquid flow amount (estimated value)". The liquid flow amount (estimated value) can be calculated using an estimation formula prepared for each of the positive electrode and the negative electrode. This estimation formula can be a multiple regression formula in which the objective variable is the liquid flow amount (estimated value) and the explanatory variables are each item of the manufacturing data obtained in the manufacturing process. The manufacturing data obtained in the manufacturing process may include data representing the manufacturing conditions and physical property data. Note that in the present embodiment, the case where the liquid flow amount is estimated using the above-mentioned estimation formula has been exemplified, but the liquid flow amount can also be estimated using other methods, such as machine learning.

[0060] The manufacturing data used in the estimation formula for the positive electrode may include at least one of the particle shape of the positive electrode active material, the basis weight of the positive electrode paste, and the density of each material in the positive electrode paste. In addition to the above, the manufacturing data may also include at least one of the specific surface area of ​​the positive electrode active material, the coating surface of the positive electrode paste, and the composite density after pressing.

[0061] The manufacturing data used in the estimation formula for the negative electrode may include at least one of the average particle size (D50) of the negative electrode active material and the coating amount of the negative electrode paste. In addition to the above-mentioned manufacturing data, at least one of the coating surface, basis weight, and thickness after pressing of the negative electrode paste may be used. Other manufacturing data that can be used in the estimation formula for the positive electrode and the negative electrode include the mixing ratio of each material contained in the composite material, the viscosity of the paste, etc.

[0062] For multiple samples, the liquid flow rate (actual measured value) and manufacturing data are obtained, and a multiple regression equation is fitted using these data to determine the constants and partial regression coefficients of the multiple regression equation. The partial regression coefficients represent the sensitivity to each explanatory variable. In general, fitting a multiple regression equation requires approximately 10 times the number of samples as the number of explanatory variables. The multiple regression equation with the constants and partial regression coefficients determined by fitting is used as an estimated equation. The liquid flow rate (estimated value) is calculated by substituting the manufacturing data into this estimated equation.

[0063] Fig. 5 is a graph showing the correlation between the estimated and measured values ​​of the liquid flow rate of the electrode body of the lithium-ion secondary battery shown in Fig. 1. It is also advisable to obtain the correlation between the liquid flow rate (estimated value) and the liquid flow rate (measured value) to verify the validity of the estimation formula. As shown in Fig. 5, the correlation is expressed by the coefficient of determination R 2 It can be expressed as the coefficient of determination R 2 The closer to 1, the higher the correlation. 2If the correlation is 0.5 or more, it can be said that there is sufficient correlation, and the estimation formula is judged to be valid. From the viewpoint of the reliability of the liquid flow rate (estimated value), the coefficient of determination R 2 is preferably 0.7 or more. 2 If is less than 0.5, it is preferable to reset the estimation equation by increasing the number of samples and redoing the fitting, reviewing the explanatory variables, etc.

[0064] In the evaluation method for a lithium-ion secondary battery according to the present embodiment, once the estimation of the liquid flow rates of the positive and negative electrodes is completed, the liquid flow ratio is then calculated from the estimated liquid flow rates. Here, the liquid flow ratio is the ratio of the liquid flow rate (estimated value) of the negative electrode plate 44 to the liquid flow rate (estimated value) of the positive electrode plate 42. In other words, the flow ratio represents the ratio of the permeation speed of the electrolyte 22 in the positive electrode plate 42 and the negative electrode plate 44.

[0065] FIG. 6 is a graph showing the relationship between the liquid flow ratio and the high-rate resistance change rate. As can be seen from FIG. 6, a positive correlation is observed between the liquid flow ratio and the high-rate resistance change rate. Here, the high-rate resistance change rate indicates the rate of change in resistance value when high-rate charging and discharging are performed. Therefore, it can be said that a battery with a low high-rate resistance change rate is less likely to suffer from high-rate deterioration and has good high-rate deterioration characteristics. Conversely, it can be said that a battery with a high high-rate resistance change rate is more likely to suffer from high-rate deterioration and has relatively poor high-rate deterioration characteristics. From this, it can be said that the lower the liquid flow ratio is, specifically, closer to 1, the relatively better the high-rate deterioration characteristics are, and the higher the liquid flow ratio is, the relatively worse the high-rate deterioration characteristics are. Note that, since it is unclear whether the correlation shown in FIG. 6 is observed when the liquid flow ratio is below 1, the lithium ion secondary battery 10 evaluated in this embodiment is adjusted so that the liquid flow amount of the positive electrode plate 42 is equal to or slightly smaller than the liquid flow amount of the negative electrode plate 44.

[0066] In this embodiment, the high-rate degradation characteristics are predicted based on the liquid flow ratio. In a specific prediction method, for example, in the graph shown in FIG. 6, a battery plotted in a region where the high-rate resistance change rate specified based on the liquid flow ratio is relatively low (for example, region A1 in FIG. 6) is evaluated as a lithium ion secondary battery 10A (see FIG. 10) having good high-rate degradation characteristics. Similarly, a battery plotted in a region where the high-rate resistance change rate specified based on the liquid flow ratio is relatively high (for example, region A2 in FIG. 6) is evaluated as a lithium ion secondary battery 10B (see FIG. 10) having poor high-rate degradation characteristics. Note that, as shown in FIG. 6, the liquid flow ratio and the high-rate degradation characteristics are closely related, so the relationship between the liquid flow ratio and the high-rate degradation characteristics may be experimentally specified in advance, and a judgment table reflecting the specified result may be prepared to predict the high-rate degradation characteristics.

[0067] After completing a series of evaluations, the lithium ion secondary battery 10 can be used in a manner suited to its performance, allowing the user to select a preferred application based on the high-rate degradation characteristics. Specifically, a lithium ion secondary battery with relatively good high-rate degradation characteristics is less likely to experience high-rate degradation even in areas with high ambient temperatures or in applications where high-rate charging and discharging is frequently performed. Therefore, it can be said that the battery is suitable for use as a power source for vehicles that run in warm regions. On the other hand, a lithium ion secondary battery with relatively poor high-rate degradation can be used while suppressing high-rate degradation in areas with low ambient temperatures or in applications where high-rate charging and discharging is not frequently performed. Therefore, it can be said that the battery is suitable for use as a power source for vehicles that run in cold regions, or as a storage battery for home use.

[0068] In order to promote use suited to the applications and the like described above, it is advisable to carry out the above-described evaluation of lithium ion secondary battery 10 after manufacture, and determine the destination for shipment taking into consideration the performance as a result of the evaluation.

[0069] An evaluation device 60 according to the present embodiment, which can realize the evaluation method for a lithium ion secondary battery according to the present embodiment, will be described below with reference mainly to FIGS. 7 and 8.

[0070] 7 is a block diagram showing an example of a hardware configuration of an evaluation device according to an embodiment of the present disclosure. As shown in FIG. 7, the evaluation device 60 according to the present embodiment may include a control unit 62, a display unit 76, an input unit 78, a communication unit 80, and a storage unit 82.

[0071] The control unit 62 can be configured, for example, by a known computer. It may include a CPU (Central Processing Unit) 64 functioning as at least one processor, a ROM (Read Only Memory) 66, a RAM (Random Access Memory) 68, a non-volatile memory 70 as an example of storage, and an input / output unit (I / O) 72. The various components described above may be connected to each other so as to be able to communicate with each other via an internal bus.

[0072] The CPU 64 may be capable of executing various programs and controlling each unit. The ROM 66 may be capable of storing various programs and various data. The RAM 68 may be capable of temporarily storing programs or data as a working area. The memory 70 may be composed of a recording medium such as a hard disk drive (HDD), a solid state drive (SSD), or a flash memory, and may at least temporarily store various programs including an operating system and various data necessary for evaluating the lithium ion secondary battery 10. The I / O 72 may transmit and receive data to and from various components of the evaluation device 60 such as a display unit 76, an input unit 78, a communication unit 80, and a storage unit 82.

[0073] Each of the display unit 76, the input unit 78, the communication unit 80, and the storage unit 82 is connected to the I / O 72, and is thereby electrically connected to the control unit 62. Of these, the display unit 76 can be configured with a display device such as an LCD (liquid crystal display) or an OELD (organic electroluminescence display), and can be used to display the evaluation results of the lithium-ion secondary battery 10, etc. The input unit 78 can be configured with an input device such as a keyboard, a mouse, a touch panel, etc., and can be used to accept input of manufacturing data and environmental information acquired by the acquisition unit 90. The communication unit 80 can be configured with a communication interface (I / F) for connecting to a communication line, and can be used to receive manufacturing data and environmental information, transmit evaluation results, etc. The storage unit 82 can be configured with an external storage device such as a HDD.

[0074] FIG. 8 is a functional block diagram showing an example of the functional configuration of the control unit of the evaluation device shown in FIG. 7. As shown in FIG. 8, the control unit 62 includes, as functional configurations (or software configurations), at least an acquisition unit 90 capable of acquiring manufacturing data of the positive electrode plate 42 and the negative electrode plate 44 constituting the electrode body 40 of the lithium ion secondary battery 10, an estimation unit 92 capable of estimating the liquid flow amount of the electrolyte 22 in the positive electrode plate 42 and the negative electrode plate 44 from the manufacturing data of the positive electrode plate 42 and the negative electrode plate 44, a calculation unit 94 capable of calculating the liquid flow ratio of the electrode body 40 from the estimated liquid flow amount of the positive electrode plate 42 and the liquid flow amount of the negative electrode plate 44, and a characteristic prediction unit 96 capable of predicting the high-rate deterioration characteristic of the lithium ion secondary battery 10 based on the calculated flow ratio. Each of these functional units can be realized by the CPU 64 in the control unit 62 described above executing a predetermined control program. The evaluation process realized by each of these functional units will be described in detail in the description of the evaluation method for lithium ion secondary batteries described below.

[0075] Next, the evaluation method for lithium-ion secondary batteries according to this embodiment will be described mainly with reference to FIG. 9. In the following description, a case where a series of evaluation processes is executed by the above-mentioned evaluation device 60 will be illustrated. Therefore, the following description also includes an explanation of the functions and effects of the evaluation device 60. The evaluation method for lithium-ion secondary batteries described below may be implemented by the CPU 64 in the control unit 62 of the evaluation device 60 executing a control program that causes the CPU 64 to execute a predetermined operation. This control program may be stored and provided in a non-transitory computer-readable medium such as the memory 70 or the storage unit 82.

[0076] The method for evaluating a lithium ion secondary battery according to this embodiment includes at least a step of acquiring manufacturing data of the positive electrode plate 42 and the negative electrode plate 44 constituting the electrode assembly 40 of the lithium ion secondary battery 10 (step S40), a step of estimating the liquid flow amount of the electrolyte 22 in the positive electrode plate 42 and the negative electrode plate 44 from the manufacturing data of the positive electrode plate 42 and the negative electrode plate 44 (step S42), a step of calculating a liquid flow ratio of the electrode assembly 40 from the estimated liquid flow amount of the positive electrode plate 42 and the liquid flow amount of the negative electrode plate 44 (step S44), and a step of predicting the high-rate degradation characteristic of the lithium ion secondary battery 10 based on the calculated liquid flow ratio (step S46). The series of processes will be described in more detail below.

[0077] 9 is a flowchart showing an example of a method for evaluating a lithium-ion secondary battery according to an embodiment of the present disclosure. In the following, a case will be described in which the method for evaluating a lithium-ion secondary battery according to the present embodiment is used to determine the destination of a lithium-ion secondary battery after it has been manufactured and before it is shipped.

[0078] When identifying the destination of a lithium ion secondary battery before shipment using the evaluation method for a lithium ion secondary battery according to the present embodiment, first, the acquisition unit 90 is operated to acquire manufacturing data of one lithium ion secondary battery 10 to be evaluated (step S40). The manufacturing data acquired here may include, for example, data representing manufacturing conditions and physical property data. This manufacturing data can be acquired in various ways, for example, by a user directly inputting it via the input unit 78, or by acquiring it from a server (not shown) via the communication unit 80. Specific examples of the manufacturing data have already been described, and therefore will not be described here.

[0079] Next, the estimation unit 92 is operated to estimate the liquid flow rate of each of the positive electrode plate 42 and the negative electrode plate 44 from the acquired manufacturing data (step S42). When estimating this liquid flow rate, an estimation formula prepared in advance for each of the positive electrode and the negative electrode can be used. The estimation formula can be based on the multiple regression formula described above. In this case, the obtained liquid flow rate is the liquid flow rate (estimated value) described above.

[0080] Once the estimation of the liquid flow rates of the positive and negative electrode plates 42, 44 is completed, the calculation unit 94 is then operated to calculate the liquid flow ratio of the electrode body 40 from the obtained liquid flow rates (step S44). Then, the characteristic prediction unit 96 predicts the high-rate degradation characteristics based on the calculated liquid flow ratio (step S46). The method of calculating the liquid flow ratio and the method of predicting the high-rate degradation characteristics are as described above. By carrying out step S46, a series of processes for evaluating the lithium-ion secondary battery is completed.

[0081] Once the prediction of the high-rate degradation characteristics is completed, in order to identify applications suitable for the lithium-ion secondary battery 10, the appropriate ranges of conditions related to degradation in the usage environment of the lithium-ion secondary battery 10 (hereinafter also referred to as "degradation conditions") and the appropriate range of temperature are identified (step S48).

[0082] Here, the deterioration conditions refer to conditions related to deterioration of the charging and discharging functions of the lithium ion secondary battery 10. Examples include frequency of use and frequency of charging. Here, as the deterioration of the lithium ion secondary battery 10 progresses and the deterioration rate (or capacity maintenance rate) increases, the frequency of occurrence of high-rate deterioration also increases. Therefore, in an environment where deterioration is likely to progress, it is advisable to use a lithium ion secondary battery with good high-rate deterioration characteristics. In this embodiment, appropriate deterioration conditions for the lithium ion secondary battery 10 are specified.

[0083] Moreover, the environmental temperature refers to the ambient temperature when the lithium ion secondary battery 10 is in use. When the environmental temperature is high, high-rate degradation is likely to occur. Therefore, for example, in warm regions, it is advisable to use a lithium ion secondary battery with good high-rate degradation characteristics. In this embodiment, the appropriate environmental temperature range for the lithium ion secondary battery 10 is specified.

[0084] In consideration of the above, in step S48, the proper deterioration condition and the environmental temperature are identified for the lithium-ion secondary battery 10. Note that, although the present embodiment illustrates the case where both the proper deterioration condition and the environmental temperature are identified, it is also possible to identify only one of them.

[0085] Next, the destination of shipment is determined based on the specified appropriate deterioration conditions and environmental temperature (step S50). For example, if the lithium ion secondary battery 10A has good high-rate deterioration characteristics, a warm region or a manufacturing factory for vehicle batteries may be selected as the destination. Similarly, if the lithium ion secondary battery 10B has poor high-rate deterioration characteristics, a cold region or a manufacturing factory for residential batteries may be selected as the destination.

[0086] As described above, according to the evaluation method and evaluation device 60 for lithium ion secondary batteries according to the present embodiment, the high-rate degradation characteristics of the lithium ion secondary battery can be accurately predicted, and therefore the performance of the lithium ion secondary battery can be evaluated with high accuracy. In addition, by carrying out the above-mentioned evaluation after the manufacture of the lithium ion secondary battery, the use application and the use environment of the lithium ion secondary battery can be determined in consideration of the high-rate degradation characteristics. Therefore, the occurrence of high-rate degradation in the lithium ion secondary battery after shipment can be prevented in advance. In addition, it is also possible to prevent the deterioration of the lithium ion secondary battery from progressing faster than expected by the user due to the occurrence of high-rate degradation.

[0087] When a lithium ion secondary battery is used as, for example, a storage battery for a vehicle, a plurality of lithium ion secondary batteries may be connected together to form a battery unit in order to ensure a desired output and capacity. In such a case, excellent results can be expected by accurately understanding the performance of the lithium ion secondary battery. Hereinafter, a battery unit manufacturing method and manufacturing support device according to the present embodiment, which are related to the above-mentioned lithium ion secondary battery evaluation method and evaluation device, will be described.

[0088] Fig. 10 is a schematic plan view showing an example of a battery unit manufactured by the manufacturing method of a battery unit according to an embodiment of the present disclosure. The battery unit 100 manufactured by the manufacturing method of a battery unit according to the present embodiment can be constructed by stacking a plurality of the above-mentioned lithium ion secondary batteries 10, for example, 30 batteries, and electrically connecting the electrodes of each lithium ion secondary battery 10 using a bus bar (not shown), as shown in Fig. 10. The battery unit 100 assembled in this manner can be mounted on, for example, a vehicle.

[0089] Fig. 11 is a graph showing an example of temperature distribution at the position where the battery unit shown in Fig. 10 is installed. The horizontal axis in Fig. 11 shows the arrangement of the lithium-ion secondary batteries 10 (cells) that make up the battery unit 100, and the vertical axis shows the environmental temperature at the position where each lithium-ion secondary battery 10 is installed.

[0090] Here, the battery unit 100 mounted in a suitable position in the vehicle is generally affected by heat generated during operation and heat from surrounding components. In this case, if the battery unit 100 is relatively large, such as for a vehicle, the environmental temperature may differ at each part of the battery unit 100. Specifically, the battery unit 100 may be used under an environmental temperature such as that shown in FIG. 11. In such a case, among the multiple lithium-ion secondary batteries 10 constituting the battery unit 100, those arranged near both ends in the connection direction of the lithium-ion secondary batteries 10 (points plotted near both ends in the horizontal direction on the graph in FIG. 11) will operate in a higher temperature environment than those arranged in the center in the connection direction (points plotted near the center in the horizontal direction on the graph in FIG. 11).

[0091] Assuming that the performance of the multiple lithium-ion secondary batteries 10 constituting the battery unit 100 used under the above conditions is exactly the same, the lithium-ion secondary batteries located closer to both ends in the connection direction will relatively frequently experience high-rate degradation. Therefore, the battery unit manufacturing method and manufacturing support device for supporting the manufacture of the battery unit according to this embodiment propose a manufacturing method and manufacturing support that take the above points into consideration.

[0092] 12 is a functional block diagram showing an example of a functional configuration of a control unit of a manufacturing support device according to an embodiment of the present disclosure. The manufacturing support device according to this embodiment may be a device capable of providing various information for supporting the manufacturing of the battery unit 100. In addition, this manufacturing support device can be realized with a similar configuration to that of the evaluation device 60 described above, except for the hardware configuration and the specific structure of the control unit. Furthermore, the control unit 62A of the manufacturing support device can be configured with a well-known computer, similar to the control unit 62 of the evaluation device 60.

[0093] As shown in FIG. 12, the functional configuration of the control unit 62A of the manufacturing support device includes at least an acquisition unit 90A capable of acquiring manufacturing data of the positive electrode plates 42 and negative electrode plates 44 constituting each electrode body 40 of the multiple lithium ion secondary batteries 10 and environmental information of the position where the battery unit 100 is installed, an estimation unit 92 capable of estimating the liquid flow amount of the electrolyte 22 in the positive electrode plates 42 and negative electrode plates 44 from the manufacturing data of the positive electrode plates 42 and negative electrode plates 44, a calculation unit 94 capable of calculating the liquid flow ratio of the electrode body 40 from the estimated liquid flow amount of the positive electrode plate 42 and the liquid flow amount of the negative electrode plate 44, a characteristic prediction unit 96 capable of predicting the high-rate deterioration characteristics of each of the multiple lithium ion secondary batteries 10 based on the calculated liquid flow ratio, and an order determination unit 98 that determines the order in which the lithium ion secondary batteries are connected based on the high-rate deterioration characteristics of each of the multiple lithium ion secondary batteries 10 and the environmental information.

[0094] Of the various functional units described above, the estimation unit 92, calculation unit 94, and characteristic prediction unit 96 are similar to those of the evaluation device 60 described above, and detailed description thereof will be omitted. On the other hand, the acquisition unit 90A can acquire environmental information of the location where the battery unit 100 is installed, in addition to the manufacturing data. Here, the environmental information refers to various information of the location where the battery unit 100 is installed, and may include at least temperature information of the location where the battery unit 100 is installed.

[0095] The order determination unit 98 determines the connection order of the multiple lithium ion secondary batteries 10 that constitute the battery unit 100. This connection order is determined using the high-rate degradation characteristics of each lithium ion secondary battery 10 as well as the environmental information acquired by the acquisition unit 90A.

[0096] Next, a method for manufacturing a battery unit according to this embodiment will be described mainly with reference to FIG. 13. In the following description, a case where a series of manufacturing processes is performed with the support of the manufacturing support device described above will be illustrated. Therefore, the following description also includes a description of the functions and effects of the manufacturing support device. Furthermore, the manufacturing method for a battery unit described below may be implemented by a CPU 64 in a control unit 62A of the manufacturing support device executing a control program that causes the CPU 64 to perform a predetermined operation.

[0097] The method for manufacturing a battery unit according to the present embodiment is a method for manufacturing a battery unit 100 in which a plurality of lithium ion secondary batteries 10 are connected, and includes at least a step of acquiring manufacturing data for the positive electrode plate 42 and the negative electrode plate 44 constituting each of the electrode bodies 40 of the plurality of lithium ion secondary batteries 10 (step S102), a step of estimating the liquid flow rate of the electrolyte 22 in the positive electrode plate 42 and the negative electrode plate 44 from the manufacturing data for the positive electrode plate 42 and the negative electrode plate 44 (step S104), and a step of calculating the liquid flow rate of the electrolyte 22 from the estimated liquid flow rate of the positive electrode plate 42 and the liquid flow rate of the negative electrode plate 44. The method includes a step of calculating a liquid flow ratio in the electrode body 40 (step S106), a step of predicting high-rate deterioration characteristics of each of the plurality of lithium-ion secondary batteries 10 based on the calculated liquid flow ratio (step S108), a step of determining an order for connecting the lithium-ion secondary batteries based on the high-rate deterioration characteristics of each of the plurality of lithium-ion secondary batteries 10 and environmental information of the location where the battery unit 100 is installed (step S112), and a step of connecting the plurality of lithium-ion secondary batteries 10 in the determined order (step S114). The series of processes will be described in further detail below.

[0098] Fig. 13 is a flowchart showing an example of a method for manufacturing a battery unit according to an embodiment of the present disclosure. In the following, a case will be described in which a battery unit 100 formed by connecting a plurality of lithium ion secondary batteries 10 as shown in Fig. 10 and used in an environment as shown in Fig. 11 is manufactured.

[0099] When manufacturing a battery unit 100 using the manufacturing method for a battery unit according to the present embodiment, first, a plurality of, for example, 30 lithium ion secondary batteries 10 to be assembled into the battery unit 100 are specified. The plurality of lithium ion secondary batteries 10 specified at this time may have variations in performance. In relation to this, the manufacturing lots of the positive electrode plates 42 and negative electrode plates 44 of the lithium ion secondary batteries 10 do not need to be the same.

[0100] In this embodiment, the lithium ion secondary batteries 10 constituting the battery unit 100 are specified in advance, but the timing of the specification can be changed. For example, a series of evaluation processes described below may be performed on a large number of lithium ion secondary batteries 10 exceeding the number of lithium ion secondary batteries 10 constituting the battery unit 100, and then the lithium ion secondary batteries 10 constituting the battery unit 100 may be selected from the large number of lithium ion secondary batteries 10.

[0101] Once the lithium ion secondary batteries 10 constituting the battery unit 100 have been identified, an evaluation process for the lithium ion secondary batteries 10 is then executed. This evaluation process is generally the same as that described in the evaluation method for lithium ion secondary batteries described above. Briefly, first, the acquisition unit 90A is operated to acquire manufacturing data for each of the identified lithium ion secondary batteries 10 (step S102). Next, the estimation unit 92 is operated to estimate the liquid flow rates of the positive electrode plate 42 and the negative electrode plate 44 from the acquired manufacturing data (step S104).

[0102] Once the estimation of the liquid flow rates of the positive electrode plate 42 and the negative electrode plate 44 is completed, the calculation unit 94 then calculates the liquid flow ratio of the electrode body 40 from the obtained liquid flow rates (step S106). Then, the characteristic prediction unit 96 is operated to predict the high-rate degradation characteristics of each lithium-ion secondary battery 10 based on the calculated liquid flow ratio (step S108). The series of evaluation processes described above are performed on all of the multiple lithium-ion secondary batteries 10 identified in step S100, whereby evaluation results of the high-rate degradation characteristics of each lithium-ion secondary battery 10 can be obtained.

[0103] Based on the evaluation result of the high-rate deterioration characteristics of each lithium-ion secondary battery 10, in this embodiment, each lithium-ion secondary battery 10 is classified into two types: lithium-ion secondary batteries 10A with good high-rate deterioration characteristics and lithium-ion secondary batteries 10B with poor high-rate deterioration characteristics. The classification result may be provided to a worker or the like who assembles the battery unit 100 via, for example, the display unit 76. Alternatively, when the assembly work of the battery unit 100 is performed by an assembly robot including a manipulator or the like, data of the classification result may be provided to a controller or the like of the robot via the communication unit 80. Note that the classification method of the multiple lithium-ion secondary batteries 10 is not limited to this. Therefore, for example, instead of the above-mentioned method, the batteries may be classified into more detailed classifications, or the classification itself may be omitted.

[0104] When the evaluation of the multiple lithium ion secondary batteries 10 constituting the battery unit 100 is completed, the acquisition unit 90A is then operated to acquire environmental information of the location where the battery unit 100 is installed (step S110). The environmental information may include temperature information of the location where the battery unit 100 is installed, and specifically, may include temperature information as shown in Fig. 11. The environmental information can be acquired using the input unit 78 and the communication unit 80.

[0105] Next, the order determination unit 98 determines the connection order of the multiple lithium ion secondary batteries 10 using the high-rate degradation characteristics predicted by the characteristic prediction unit 96 and the environmental information (step S112). Specifically, the arrangement of the lithium ion secondary batteries 10A, 10B classified into two groups based on the prediction results of the high-rate degradation characteristics of each lithium ion secondary battery 10 is determined based on the temperature distribution at the position where the battery unit 100 is installed, which is acquired as the environmental information.

[0106] 11, it can be determined that the positions of the battery unit 100 near both ends in the connection direction of each lithium-ion secondary battery 10 tend to be higher in temperature than the position corresponding to the center in the connection direction. Therefore, the connection order of the lithium-ion secondary batteries 10 may be determined so that the lithium-ion secondary batteries 10A with good high-rate degradation characteristics are arranged near both ends in the connection direction, and the lithium-ion secondary batteries 10B with poor high-rate degradation characteristics are arranged in the center in the connection direction, as shown in FIG. 10. The connection order determined here is provided to an operator, etc., via the display unit 76, communication unit 80, etc.

[0107] Once the connection order of the lithium ion secondary batteries 10 has been determined, the lithium ion secondary batteries 10 are connected in accordance with the determined order to assemble the battery unit 100 (step S114). This assembly work can be performed by a worker or an assembly robot, and includes work such as attaching a bus bar in addition to the work of connecting the lithium ion secondary batteries 10. As long as the assembly work of the battery unit 100 includes the above-mentioned work of connecting the lithium ion secondary batteries 10, there are no particular limitations on the other detailed work contents.

[0108] As described above, according to the battery unit manufacturing method and manufacturing support device of the present embodiment, the arrangement of the multiple lithium ion secondary batteries included in the battery unit can be determined taking into consideration environmental information and the high-rate degradation characteristics of the lithium ion secondary batteries. Therefore, for example, among the positions at which the battery unit 100 is installed, it is possible to adjust the arrangement so that lithium ion secondary batteries with relatively high high-rate degradation characteristics are arranged at positions where the temperature is relatively high, thereby making it possible to suppress the frequency of high-rate degradation occurring in the battery unit 100.

[0109] In the present embodiment, a case has been exemplified in which the temperature at the position where the battery unit 100 is installed is relatively high at both ends in the connection direction of the lithium-ion secondary batteries 10. However, for example, there may be cases in which the temperature at the center in the connection direction becomes relatively high due to heat transfer from the lithium-ion secondary batteries 10 themselves. In such a case, the same effect as that of the above-described embodiment can be obtained by arranging the lithium-ion secondary battery 10A, which has good high-rate degradation characteristics, in the center in the connection direction.

[0110] In addition, the above-described battery units 100 are illustrated as being connected such that the flat rectangular lithium ion secondary batteries 10 have their largest flat surfaces facing each other, but the connection structure of the battery units 100 is not limited to this.

[0111] The present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present disclosure, all of which are included in the technical concept of the present disclosure. [Explanation of symbols]

[0112] 10 Lithium-ion secondary battery 22 Electrolyte 40 Electrode body 42 Positive electrode plate (example of positive electrode) 42A positive electrode current collector 42B Positive electrode active material layer 44 Negative electrode plate (an example of a negative electrode) 44A negative electrode current collector 44B Negative electrode active material layer 46 Separator 60 Evaluation Equipment 62, 62A Control section 90, 90A acquisition part 92 Estimation part 94 Calculation section 96 Characteristics Prediction Section 98 Order determining part 100 Battery Unit

Claims

1. Obtaining manufacturing data for a positive electrode and a negative electrode constituting an electrode body of a lithium ion secondary battery; estimating a liquid flow rate of the electrolyte in the positive electrode and the negative electrode from the manufacturing data of the positive electrode and the negative electrode; calculating a liquid flow ratio of the electrode assembly from the estimated liquid flow amount of the positive electrode and the estimated liquid flow amount of the negative electrode; and predicting high-rate degradation characteristics of the lithium ion secondary battery based on the calculated liquid flow ratio. Evaluation method for lithium-ion secondary batteries.

2. the step of estimating the liquid flow amount includes estimating the liquid flow amount using a multiple regression equation in which the liquid flow amount of the positive electrode or the negative electrode is a response variable and the production data of the positive electrode or the negative electrode is an explanatory variable; A method for evaluating the lithium ion secondary battery according to claim 1 .

3. The manufacturing data of the positive electrode includes at least one of a particle shape of a positive electrode active material contained in the positive electrode, a basis weight of a positive electrode paste, and a density of each material in the positive electrode paste. The method for evaluating the lithium ion secondary battery according to claim 2 .

4. The manufacturing data of the negative electrode includes at least one of an average particle size of a negative electrode active material contained in the negative electrode and a coating amount of a negative electrode paste. The method for evaluating the lithium ion secondary battery according to claim 2 .

5. and determining an appropriate range of conditions related to deterioration of an environment in which the lithium ion secondary battery is used based on the predicted high-rate deterioration characteristics of the lithium ion secondary battery. A method for evaluating the lithium ion secondary battery according to claim 1 .

6. and determining an appropriate range of an environmental temperature in which the lithium ion secondary battery is used based on the predicted high-rate deterioration characteristics of the lithium ion secondary battery. A method for evaluating the lithium ion secondary battery according to claim 1 .

7. A method for manufacturing a battery unit in which a plurality of lithium ion secondary batteries are connected, comprising the steps of: acquiring manufacturing data of positive electrodes and negative electrodes constituting each of the electrode bodies of the plurality of lithium ion secondary batteries; estimating a liquid flow rate of the electrolyte in the positive electrode and the negative electrode from the manufacturing data of the positive electrode and the negative electrode; calculating a liquid flow ratio of the electrode assembly from the estimated liquid flow amount of the positive electrode and the estimated liquid flow amount of the negative electrode; predicting high-rate degradation characteristics of each of the plurality of lithium ion secondary batteries based on the calculated liquid flow ratio; determining an order in which the lithium ion secondary batteries are connected based on high-rate deterioration characteristics of each of the plurality of lithium ion secondary batteries and environmental information of a location where the battery unit is installed; and connecting the plurality of lithium ion secondary batteries in the determined order. A manufacturing method of a battery unit.

8. The environmental information includes temperature information at a location where the battery unit is installed. The method for manufacturing the battery unit according to claim 7 .

9. An acquisition unit capable of acquiring manufacturing data of a positive electrode and a negative electrode constituting an electrode body of a lithium ion secondary battery; an estimation unit capable of estimating a liquid flow rate of the electrolyte in the positive electrode and the negative electrode from the manufacturing data of the positive electrode and the negative electrode; a calculation unit capable of calculating a liquid flow ratio of the electrode assembly from the estimated liquid flow amount of the positive electrode and the estimated liquid flow amount of the negative electrode; and a characteristic prediction unit capable of predicting high-rate deterioration characteristics of the lithium ion secondary battery based on the calculated liquid flow ratio. Evaluation equipment.

10. A manufacturing support device that supports manufacturing of a battery unit in which a plurality of lithium ion secondary batteries are connected, an acquisition unit capable of acquiring manufacturing data of positive electrodes and negative electrodes constituting each electrode body of the plurality of lithium ion secondary batteries and environmental information of a location where the battery unit is installed; an estimation unit capable of estimating a liquid flow rate of the electrolyte in the positive electrode and the negative electrode from the manufacturing data of the positive electrode and the negative electrode; a calculation unit capable of calculating a liquid flow ratio of the electrode assembly from the estimated liquid flow amount of the positive electrode and the estimated liquid flow amount of the negative electrode; a characteristic prediction unit capable of predicting high-rate degradation characteristics of each of the plurality of lithium ion secondary batteries based on the calculated liquid flow ratio; and an order determination unit that determines an order in which the lithium ion secondary batteries are connected based on high-rate degradation characteristics of each of the plurality of lithium ion secondary batteries and the environmental information. Manufacturing support equipment.

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