Battery diagnostic method, information processing apparatus, battery system and program

Abstract

To provide a battery diagnostic method capable of determining gas generation which is one of concrete factors of deterioration, an information processing apparatus, a battery system, and a program.SOLUTION: The battery diagnostic method includes the steps of: calculating a first dQ / dV curve from a first charge / discharge curve of a secondary battery; acquiring first peak and second peak of the first dQ / dV curve; calculating a second dQ / dV curve from a second charge / discharge curve of the secondary battery; acquiring third peak and fourth peak of the second dQ / dV curve; calculating a first shift amount from the first peak to the third peak and a second shift amount from the second peak to the fourth peak; and determining gas generation on the basis of difference between the first shift amount and the second shift amount.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery diagnostic method, an information processing device, a battery system, and a program. [Background technology]

[0002] In recent years, the internal state of batteries such as secondary batteries has been estimated based on measurement data including measurement values ​​such as the battery current and voltage, and battery deterioration has been determined based on the estimated internal state results.

[0003] In batteries such as secondary batteries, repeated charging and discharging causes the battery characteristics to change, i.e., deteriorate, due to expansion and contraction of the secondary battery compared to when it was first used, or deterioration of the positive and negative electrode active materials. The deterioration of this secondary battery is determined by measuring the electrical characteristics of the secondary battery and evaluating the changes. However, this deterioration determination does not directly determine the cause of the deterioration. Therefore, there is a need for an appropriate deterioration determination by identifying the specific cause of the deterioration. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-145063 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-54082 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a battery diagnostic method, an information processing device, a battery system, and a program that are capable of determining gas generation, which is one of the specific causes of deterioration. [Means for solving the problem]

[0006] According to an embodiment, a battery diagnostic method is provided, which includes the steps of calculating a first dQ / dV curve from a first charge / discharge curve of a secondary battery, obtaining a first peak and a second peak of the first dQ / dV curve, calculating a second dQ / dV curve from a second charge / discharge curve of the secondary battery, obtaining a third peak and a fourth peak of the second dQ / dV curve, calculating a first shift amount from the first peak to the third peak and a second shift amount from the second peak to the fourth peak, and determining gas generation based on the difference between the first shift amount and the second shift amount. [Brief explanation of the drawings]

[0007] [Figure 1] Graph showing the dQ / dV curve of a lithium-ion secondary battery. [Figure 2] 10 is a graph showing the relationship between gas generation and change in peak potential. [Figure 3] FIG. 1 is a block diagram showing an example of a schematic configuration of a battery system according to an embodiment. [Figure 4] 3 is a flowchart showing an example of a battery diagnosis method according to the embodiment. [Figure 5] 3 is a flowchart showing an example of a battery diagnosis method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings. In the following description, components that perform the same or similar functions are designated by the same reference numerals throughout the drawings, and redundant description will be omitted. Each drawing is a schematic diagram for explaining and facilitating understanding of the embodiments, and the shapes, dimensions, ratios, etc. may differ from those of an actual device. However, these may be appropriately modified in design, taking into consideration the following description and known techniques.

[0009] This specification describes lithium-ion secondary batteries. Battery capacity is defined as the charge capacity (amount of charge charge) until the SOC (State of Charge) value changes from 0% to 100% when charging under specified conditions, or the discharge capacity (amount of discharge charge) until the SOC value changes from 100% to 0% when discharging under specified conditions. The SOC of a lithium-ion secondary battery is defined as the ratio of the remaining charge (remaining capacity) to the battery capacity of the secondary battery until the SOC value reaches 0.

[0010] A lithium-ion secondary battery has a positive electrode and a negative electrode as electrodes, and the positive electrode and the negative electrode have opposite polarities to each other. The potential of each of the positive electrode and the negative electrode of a lithium-ion secondary battery changes in response to changes in the state of charge. Each of the positive electrode and the negative electrode has a predetermined relationship between the potential and the state of charge. Therefore, for each electrode of a lithium-ion secondary battery, the potential can be calculated based on the state of charge, and the state of charge can be calculated based on the potential.

[0011] Before describing the embodiments, the findings that led to the determination of gas generation in the embodiments will be described. FIG. 1 is a graph of dQ / dV curves created from the charge / discharge curves of a lithium-ion secondary battery. The horizontal axis represents voltage, the vertical axis represents the potential derivative of capacity, and the area of ​​each curve represents capacity. The dotted line represents the curve before the start of cycling, the solid line represents the curve after 200 cycles, and the dashed line represents the curve after 400 cycles. Each curve has peaks near 2.1 V and 2.8 V. The peak near 2.1 V is designated Peak A, and the peak near 2.8 V is designated Peak B. All curves are charge / discharge curves for SOC values ​​ranging from 0% to 100%.

[0012] As can be seen from Figure 1, as the number of cycles increases, Peak A shifts to the higher voltage side. Meanwhile, Peak B shifts to the lower voltage side, with the rate of change of Peak B being greater than that of Peak A. Furthermore, as the number of cycles increases, the area under the curve decreases. If Peak B shifts to the lower voltage side or Peak A shifts to the higher voltage side, it is believed that the lithium-ion secondary battery is deteriorating.

[0013] FIG. 2 shows a graph plotting the volume of gas generated versus the difference in peak voltage change in the dQ / dV curve for a lithium-ion secondary battery. The change in peak voltage refers to the change between Peak A and Peak B in the dQ / dV curve in FIG. 1. The larger the change, the greater the shift toward lower or higher voltages. The difference in change is calculated by subtracting the change in Peak A from the change in Peak B. The gas volume was measured using the Archimedes method when the SOC value of the lithium-ion secondary battery was 50%. As the difference in change increases, i.e., the shift width increases, the gas volume also gradually increases. When the difference in change exceeds 0.07, the gas volume suddenly increases. In the present invention, this relationship is used to determine that a lithium-ion secondary battery is deteriorating, and therefore gas is being generated, when the shift width increases.

[0014] (First embodiment) FIG. 3 is a block diagram showing an example of a schematic of a battery system according to an embodiment. In this embodiment, the battery system 1 includes an information processing device 3 and a lithium-ion secondary battery 4. The lithium-ion secondary battery 4 is included in a secondary battery device 2. In addition to the lithium-ion secondary battery 4, the secondary battery device 2 includes a measurement unit 5, a first storage medium 6, a control circuit 7, a charge / discharge circuit 8, and a first communication module 9. The measurement unit 5 includes a current measurement circuit 51 for the lithium-ion secondary battery 4 and a voltage measurement circuit 52 for measuring the voltage. The measurement unit 5 may further include a temperature sensor 53 and a timer 54. The first storage medium 6 includes a first data management program 61 capable of managing data transfer and a battery measurement program 62 for measuring the SOC and voltage of the lithium-ion secondary battery 4. The information processing device 3 includes a second storage medium 60, a processing circuit 17, and a second communication module 19. The information processing device 3 may further include a user interface 20. The second storage medium 60 stores a second data management program 63 that can manage data input and output, and a charge control program 64 that can control charging of the lithium ion secondary battery 4.

[0015] The charge control program 64 includes a charge / discharge curve calculation program 65 capable of calculating a charge / discharge curve from the SOC and potential acquired by the battery measurement program 62, a dQ / dV calculation program 66 capable of calculating a dQ / dV curve from the charge / discharge curve calculated by the charge / discharge curve calculation program 65, and a voltage V at peak A of the dQ / dV curve calculated by the dQ / dV calculation program 66. A The first peak voltage calculation program 67A can calculate the voltage V at the peak B of the dQ / dV curve calculated by the dQ / dV calculation program 66. B A second peak voltage calculation program 67B capable of calculating the voltage V A Shift ΔV A A first shift amount calculation program 68A capable of calculating the voltage V B Shift ΔV B A second shift amount calculation program 68B capable of calculating ΔV A and ΔV B The charging control program 64 includes a difference calculation program 69 capable of calculating the difference between the calculated value and the actual value; a gas generation determination program 70 capable of determining gas generation based on the value calculated by the difference calculation program 69; and an operating condition control program 71 capable of controlling the operating conditions of the lithium ion secondary battery 4 based on the determination result of the gas generation determination program 70. The charging control program 64 may further include a notification program 72. The programs included in the charging control program 64 do not need to be stored in the second storage medium 60. For example, it is sufficient for the programs to receive instructions for executing the programs issued from the processing circuit 17 and execute the programs. Therefore, the programs may be stored in separate storage media or may be run in the cloud.

[0016] Examples of the secondary battery device 2 include large-scale power storage devices for power systems, smartphones, vehicles, stationary power supply devices, robots, drones, etc. Examples of vehicles that can be used as the secondary battery device 2 include railcars, electric buses, electric cars, plug-in hybrid cars, and electric motorcycles. Any device that uses a secondary battery can be used.

[0017] The positive electrode of the lithium ion secondary battery 4 is made of a material containing an NCM (nickel-cobalt-manganese)-based material. The approximate composition ratio of the NCM-based material is nickel:cobalt:manganese=8:1:1. The positive electrode of the lithium ion secondary battery 4 is made of, for example, LiNi x Co y Mn (1-x-y) O2, where x is 0.5 or more and 0.9 or less, y is 0.05 or more and 0.45 or less, and 1-xy>0. The negative electrode active material is, for example, composed of a material containing lithium titanate, niobium titanium oxide, niobium oxide, or carbon. Among negative electrode active materials, niobium titanium oxide and niobium oxide are effective against gas generation. A lithium-ion secondary battery 4 containing at least one of these negative electrode active materials or positive electrode active materials has a plateau region with little voltage change in its charge / discharge curve. The plateau region of the charge / discharge curve extends with increasing charge / discharge cycles, shifting the positive electrode potential toward a higher potential. Because the shift in positive electrode potential leads to a peak shift in the aforementioned dQ / dV curve, it is desirable for the lithium-ion secondary battery 4 to use an electrode active material with a plateau region.

[0018] The measurement unit 5 is capable of detecting and measuring parameters related to the lithium ion secondary battery 4 at a plurality of measurement points in time, such as when the lithium ion secondary battery 4 is being charged or discharged.

[0019] The current measurement circuit 51 acquires the current value of the lithium ion secondary battery 4 .

[0020] The voltage measurement circuit 52 acquires the voltage value of the lithium ion secondary battery 4 .

[0021] The temperature sensor 53 is attached directly to the lithium ion secondary battery 4, for example, and periodically acquires the temperature of the lithium ion secondary battery 4.

[0022] The timer 54 can measure the time when the parameters relating to the lithium ion secondary battery 4 are measured.

[0023] The first storage medium 6 is a storage device called a main storage device or an auxiliary storage device. Examples of the first storage medium 6 include a magnetic disk, an optical disk (CD-ROM, CD-R, DVD, etc.), a magneto-optical disk (MO, etc.), and a semiconductor memory. The secondary battery device 2 may be provided with only one memory or multiple memories serving as the first storage medium 6. The first storage medium 6 stores data such as programs executed by the control circuit 7, data resulting from the execution of the programs, and data measured by the measurement unit 5.

[0024] The control circuit 7 is composed of a processor or an integrated circuit, and the processor constituting the control circuit 7 includes any of a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), a microcontroller (microcontroller unit), an FPGA (Field Programmable Gate Array), and a DSP (Digital Signal Processor). The control circuit 7 may be composed of one processor or multiple processors. The control circuit 7 reads and executes a program stored in the first storage medium 6 to control charging and discharging of the lithium ion secondary battery 4 via the charge / discharge circuit 8. The control circuit 7 switches between a state in which the lithium ion secondary battery 4 is charged and a state in which the lithium ion secondary battery 4 is discharged, for example, by switching the state of the charge / discharge circuit 8. Furthermore, when the lithium ion secondary battery 4 is being charged, the control circuit 7 controls the operation of a power supply 10 that supplies power to the lithium ion secondary battery 4 and the operation of the charge / discharge circuit 8, thereby adjusting the magnitude of the current input to the lithium ion secondary battery 4.

[0025] The control circuit 7 reads and executes the battery measurement program 62 from the first storage medium 6 to measure the SOC of the lithium-ion secondary battery 4. The control circuit 7 can acquire measurement results of parameters related to the lithium-ion secondary battery 4, such as data on the current and voltage values ​​of the lithium-ion secondary battery 4, from the measurement unit 5, and input measurement data including these measurement results and data on the calculated SOC into the first storage medium 6. The control circuit 7 can also transmit data obtained by the battery measurement program 62 to the information processing device 3 via the first communication module 9. The measurement data includes measurement values ​​and changes (time history) at multiple measurement points. The measurement data may also include changes (time history) in the current of the lithium-ion secondary battery 4, changes (time history) in the voltage of the lithium-ion secondary battery 4, and changes (time history) in the temperature of the lithium-ion secondary battery 4. The processing circuit 17 of the information processing device 3 receives the data transmitted from the secondary battery device 2 via the second communication module 19.

[0026] In the secondary battery device 2, the control circuit 7, the first storage medium 6, and the like constitute a BMU (Battery Management Unit).

[0027] The charge / discharge circuit 8 is equipped with, for example, an AC / DC converter and a transformer circuit. In the charge / discharge circuit 8, the AC / DC converter or the like converts AC power from the power source 10 into DC power, and the transformer circuit or the like transforms the voltage of the power supplied from the power source 10 into a voltage compatible with the lithium ion secondary battery 4. As a result, DC power at a voltage compatible with the lithium ion secondary battery 4 is supplied to the lithium ion secondary battery 4, and a charging current is input to the lithium ion secondary battery 4.

[0028] The first communication module 9 is composed of a communication interface of the secondary battery device 2. The control circuit 7 is capable of communicating with processing devices external to the secondary battery device 2, including the information processing device 3, via the first communication module 9.

[0029] The information processing device 3 is a processing device (computer) such as a server provided outside the secondary battery device 2, and communicates with the first communication module 9 of the secondary battery device 2 via the second communication module 19.

[0030] The second storage medium 60 included in the information processing device 3 is a storage device called a main storage device or an auxiliary storage device. For example, the information processing device 3 may be provided with only one storage device serving as the second storage medium 60, or may be provided with multiple storage devices.

[0031] The processing circuit 17 included in the information processing device 3 is composed of a processor or an integrated circuit, etc., and the processor constituting the processing circuit 17 may be any of a CPU, ASIC, microcomputer, FPGA, DSP, etc. The processing circuit 17 may be composed of one processor, etc., or may be composed of multiple processors, etc. The processing circuit 17 performs processing by executing programs, etc. stored in the second storage medium 60. In the example of FIG. 2 , the processing circuit 17 writes data to the second storage medium 60 and reads data from the second storage medium 60 by executing a second data management program 63. The processing circuit 17 also executes a charge control program 64 to perform the processing described below in controlling the lithium ion secondary battery 4.

[0032] The second communication module 19 is composed of a communication interface of a processing device that constitutes the information processing device 3. The processing circuit 17 communicates with devices external to the information processing device 3, including the secondary battery device 2, via the second communication module 19.

[0033] The user interface 20 can output information related to the information processing of the lithium ion secondary battery 4 and can receive input related to the information processing of the lithium ion secondary battery 4 from users of the information processing device 3 and the battery system 1. For this purpose, the user interface 20 is provided with an output device that outputs information related to the information processing of the lithium ion secondary battery 4. The output device outputs information to the outside by displaying on a screen, emitting sound, vibrating, etc. Note that the output device can receive instructions from the processing circuit 17 and output information such as gas generation to the user. The user interface 20 is also provided with an input device through which the user inputs operations. The input device is composed of, for example, one or more of a button, a mouse, a touch panel and keyboard, a voice input device, etc. Note that the user interface 20 may be provided separately from the processing device that constitutes the information processing device 3.

[0034] The flow of the battery diagnostic method according to the embodiment will be described. FIG. 4 is a flowchart showing an example of the flow of the battery diagnostic method according to the embodiment. Note that this flowchart is only an example, and the order of the processes is not limited as long as the required processing results can be obtained. Furthermore, each processing result may be stored sequentially in the second storage medium 60, and each step may acquire the processing result by referring to the second storage medium 60. The same applies to the subsequent flowcharts.

[0035] 4, the control circuit 7 reads and executes the battery measurement program 62 to obtain information about the SOC and voltage. The battery measurement program 62 is repeatedly executed at predetermined time intervals. The data about the SOC and voltage may be stored in the first storage medium 6 in advance, or may be obtained by downloading the data each time from an information processing device 3 external to the secondary battery device 2 or from the cloud.

[0036] In S1, the processing circuit 17 reads and executes the charge / discharge curve calculation program 65 to calculate a charge / discharge curve (first charge / discharge curve) of the lithium ion secondary battery 4 using the SOC and voltage values ​​of the lithium ion secondary battery 4 acquired by the battery measurement program 62. The measured SOC and voltage values ​​are transmitted to the information processing device 3 via the first communication module 9, and the processing circuit 17 calculates the charge / discharge curve via the second communication module 19.

[0037] In S2, the processing circuit 17 reads and executes the dQ / dV calculation program 66 to calculate a dQ / dV curve (first dQ / dV curve) using the charge / discharge curve calculated in S1 and the voltage value acquired by the battery measurement program 62.

[0038] In S3A, the processing circuit 17 reads and executes the first peak voltage calculation program 67A to obtain peak A (first peak) from the dQ / dV curve calculated in S2, and calculates the voltage V of peak A. A Specifically, the peak located on the lowest voltage side of the dQ / dV curve is defined as Peak A. Using the dQ / dV curve in Figure 1 as an example, the peak near 2.1V is Peak A.

[0039] In S3B, the processing circuit 17 reads and executes the second peak voltage calculation program 67B to obtain peak B (second peak) from the dQ / dV curve calculated in S2, and calculates the voltage V of peak B. B Specifically, the peak located on the highest voltage side of the dQ / dV curve is defined as Peak B. Using the dQ / dV curve in Figure 1 as an example, the peak near 2.8V is Peak B.

[0040] In S4, the processing circuit 17 reads and executes the charge / discharge curve calculation program 65 to calculate a charge / discharge curve (second charge / discharge curve) of the lithium ion secondary battery 4 at a timing different from the charge / discharge curve calculated in S1. The method for calculating the charge / discharge curve is the same as in S1. The timing for calculating the charge / discharge curve in S4 can be, for example, a time later than S1. The elapsed time from S1 to S4 is the usage time of the lithium ion secondary battery 4. The elapsed time from S1 to S4 may be the time measured by the timer 54, or a value obtained from an external server, etc. Alternatively, the charge / discharge cycle may be used instead of the time. Specifically, the timing for calculating the charge / discharge curve in S4 is calculated for a charge / discharge cycle different from S1. When the number of charge / discharge cycles is used as a reference, it is determined from the changes in current and voltage measured by the measurement unit 5 whether the lithium ion secondary battery 4 has achieved the number of cycles required for analyzing the dQ / dV curve. V A and V B The information may be stored in advance in the second storage medium 60, or may be obtained by downloading it each time from an information processing device 3 external to the secondary battery device 2 or from the cloud.

[0041] In S5, the processing circuit 17 reads and executes the dQ / dV calculation program 66 to calculate a dQ / dV curve (a second dQ / dV curve) using the charge / discharge curve calculated in S4 and the voltage value acquired by the battery measurement program 62.

[0042] In S6A, the processing circuit 17 reads and executes the first peak voltage calculation program 67A to obtain a peak A' (third peak) after the peak A has shifted from the dQ / dV curve calculated in S5, and calculates the voltage V of the peak A'. A ' is calculated.

[0043] In S6B, the processing circuit 17 reads and executes the second peak voltage calculation program 67B to obtain a peak B' (fourth peak) after the peak B has shifted from the dQ / dV curve calculated in S5, and calculates the voltage V of the peak B'. B ' is calculated.

[0044] In S7A, the processing circuit 17 reads and executes the first shift amount calculation program 68A to calculate the V calculated in S3A. A and V calculated by S6A A ' and the shift amount (first shift amount) of peak A, ΔV A Calculate ΔV A is |V A -V A It can be expressed as '|'.

[0045] In S7B, the processing circuit 17 reads and executes the second shift amount calculation program 68B to calculate the V calculated in S3B. B and V calculated by S6B B ' and the shift amount of peak B (second shift amount) ΔV B Calculate ΔV B is |V B '-V B | can be expressed as

[0046] In S8, the processing circuit 17 reads and executes the difference calculation program 69 to calculate the ΔV calculated in S7A. A and ΔV calculated by S7B B Using this, the shift amount of peak A ΔV A and the shift amount of peak B ΔV B the difference (for example, |ΔV A -ΔV B By taking into account multiple peak shifts between Peak A and Peak B, it is possible to more accurately determine gas generation.

[0047] In S9, the processing circuit 17 reads and executes the gas generation determination program 70 to determine whether gas is being generated inside the lithium ion secondary battery 4, based on the value calculated in S5. Specifically, the calculated |ΔV A -ΔV B Compare the value of | with the threshold X. |ΔV A -ΔV B If the value of | is greater than the threshold value X (YES in S9), it is determined that gas is being generated in the lithium ion secondary battery 4, and the process proceeds to S10A. A -ΔV B If the value of | is equal to or less than the threshold value (NO in S9), it is determined that the lithium ion secondary battery 4 is not generating gas.

[0048] Here, "gas generation" means that gas is being generated and that if the current operating conditions are maintained, the deterioration of the lithium-ion secondary battery 4 will progress further, which could cause the exterior material to expand. Therefore, it is necessary to slow down the deterioration of the lithium-ion secondary battery 4 and extend its lifespan.

[0049] On the other hand, even if it is determined that no gas is being generated, it is possible that gas is being generated. However, it is assumed that the amount of gas being generated is not problematic even under the current operating conditions, and no changes are made to the operating conditions.

[0050] The threshold value X is preferably greater than 0 and less than 0.2. The threshold value X can be changed as appropriate depending on the electrode active material of the lithium-ion secondary battery 4, the capacity maintenance rate, the surrounding environment, etc. Data regarding the threshold value X may be stored in advance in the second storage medium 60, or the data may be obtained by downloading each time from an information processing device 3 external to the secondary battery device 2 or from the cloud, etc.

[0051] In S10A, the processing circuit 17 reads and executes the operating condition control program 71 to ensure stable operation of the lithium ion secondary battery 4. For example, the processing circuit 17 instructs the charge / discharge circuit 8 to change the upper limit voltage and / or lower limit voltage of the lithium ion secondary battery 4. Specifically, the processing circuit 17 lowers the upper limit voltage or raises the lower limit voltage of the operating conditions. By lowering the upper limit voltage or raising the lower limit voltage of the lithium ion secondary battery 4, it is possible to reduce side reactions such as changes in the electrode structure or electrolyte, and to suppress heat generation in the lithium ion secondary battery 4. |ΔV A -ΔV B If the value of | is greater than a threshold, for example, 0.2 V or greater, the operation of the lithium ion secondary battery 4 can be stopped.

[0052] In this embodiment, the generation of gas is determined using the dQ / dV curve, which is the result of electrical measurement. Therefore, regardless of the shape of the lithium ion secondary battery 4, it is possible to determine whether gas is being generated inside the lithium ion secondary battery 4 while continuing operation.

[0053] (Second embodiment) In the second embodiment, a modified example in which gas generation is notified instead of the operation control of the first embodiment will be described. The gas generation notification in the second embodiment can also be used in combination with the operation control in the first embodiment.

[0054] The flow of the battery diagnostic method according to the embodiment will now be described. Fig. 5 is a flowchart showing a modified example of the flow of the battery diagnostic method according to the embodiment. Steps S1 to S9 are the same as those in Fig. 1. Therefore, only step S10B will be described here, and a description of steps S1 to S9 will be omitted.

[0055] In S10B, the processing circuit 17 reads and executes the notification program 72, thereby displaying a notification of gas generation on the user interface 20. Upon receiving the instruction, the user interface 20 outputs the notification of gas generation via an output device. When the step of notifying gas generation is used in conjunction with the step (S10A) of executing operational control in the battery diagnostic method of the first embodiment, S10B can be added before or after the execution of operational control, i.e., between S9 and S10A, or after S10A.

[0056] (Other embodiments) The lithium ion secondary battery in this specification may be formed from two or more unit cells (single cells), or may be formed by electrically connecting multiple unit cells. When the lithium ion secondary battery 4 is formed from multiple unit cells, the multiple unit cells may be electrically connected in series or in parallel. Furthermore, the lithium ion secondary battery may have both a series connection structure in which multiple unit cells are connected in series and a parallel connection structure in which multiple unit cells are connected in parallel. Furthermore, when a structure in which multiple unit cells are electrically connected is adopted, charge / discharge curves of the multiple unit cells may be obtained and operation may be controlled individually. Furthermore, multiple unit cells may be grouped and controlled for each group. In this case, recovery processing may be performed on all unit cells in the group based on the result of calculating a charge / discharge curve from one unit cell.

[0057] The shape of the lithium ion secondary battery 4 may be, but is not limited to, a cylindrical shape, a square shape, or a pouch shape. The lithium ion secondary battery 4 may be covered with a laminate film as an exterior, or may be covered with a metal can.

[0058] According to one or more of the embodiments and examples described above, a battery diagnostic method is provided, which includes the steps of calculating a first dQ / dV curve from a first charge / discharge curve of a secondary battery, obtaining a first peak and a second peak of the first dQ / dV curve, calculating a second dQ / dV curve from a second charge / discharge curve of the secondary battery, obtaining a third peak and a fourth peak of the second dQ / dV curve, calculating a first shift amount from the first peak to the third peak and a second shift amount from the second peak to the fourth peak, and determining gas generation based on the difference between the first shift amount and the second shift amount. The battery diagnostic method according to the embodiment can provide a battery diagnostic method capable of determining gas generation, which is one specific cause of deterioration.

[0059] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0060] The following describes the invention in terms of embodiments.

[0061] <1> calculating a first dQ / dV curve from a first charge / discharge curve of the secondary battery; obtaining a first peak and a second peak of the first dQ / dV curve; calculating a second dQ / dV curve from a second charge / discharge curve of the secondary battery; obtaining a third peak and a fourth peak of the second dQ / dV curve; calculating a first shift amount from the first peak to the third peak and a second shift amount from the second peak to the fourth peak; determining whether gas is generated based on a difference between the first shift amount and the second shift amount; Including, Battery diagnostic methods.

[0062] <2> The second charge / discharge curve is calculated according to the charge / discharge cycle and / or the elapsed time. <1> The battery diagnostic method according to claim 1.

[0063] <3> controlling an upper limit voltage and / or a lower limit voltage of an operating condition of the secondary battery based on the determination of the generation of gas; further comprising: <1> or <2> The battery diagnostic method according to claim 1.

[0064] <4> notifying the occurrence of gas based on the determination of the occurrence of gas; further comprising: <1> from <3> The battery diagnostic method according to any one of the above.

[0065] <5> The positive electrode of the secondary battery is LiNi x Co y Mn (1-x-y) O2 (x is 0.5 or more and 0.9 or less, y is 0.05 or more and 0.45 or less, 1-xy>0) <1> from <4> The battery diagnostic method according to any one of the above.

[0066] <6> The negative electrode of the secondary battery is lithium titanate, niobium titanium oxide, niobium oxide, or carbon; <1> from <5> The battery diagnostic method according to any one of the above.

[0067] <7> calculating a first dQ / dV curve from a first charge / discharge curve of the secondary battery; obtaining a first peak and a second peak of the first dQ / dV curve; calculating a second dQ / dV curve from a second charge / discharge curve of the secondary battery; obtaining a third peak and a fourth peak of the second dQ / dV curve; calculating a first shift amount from the first peak to the third peak and a second shift amount from the second peak to the fourth peak; determining whether gas is generated based on the difference between the first shift amount and the second shift amount; processing circuitry; Information processing device.

[0068] <8> <7> an information processing device according to the secondary battery controlled by the information processing device, Battery system.

[0069] <9> a user interface that can output information related to the information processing of the secondary battery or can input information related to the information processing of the secondary battery; <8> The battery system according to claim 1.

[0070] <10> The processing circuit calculating a first dQ / dV curve from a first charge / discharge curve of the secondary battery; obtaining a first peak and a second peak of the first dQ / dV curve; calculating a second dQ / dV curve from a second charge / discharge curve of the secondary battery; obtaining a third peak and a fourth peak of the second dQ / dV curve; calculating a first shift amount from the first peak to the third peak and a second shift amount from the second peak to the fourth peak; determining whether gas is generated based on the difference between the first shift amount and the second shift amount; program. [Explanation of symbols]

[0071] 1 Battery System 2 Secondary battery device 3. Information processing equipment 4. Lithium-ion secondary battery 5. Measurement Unit 6 First storage medium 7 Control Circuit 8 Charge / discharge circuit 9. First communication module 10 Power supply 17 Processing circuit 19 Second communication module 20 User Interface 51 Current measurement circuit 52 Voltage measurement circuit 53 Temperature Sensor 54 Timer 60 Second storage medium 61 First Data Management Program 62 Battery Measurement Program 63 Second Data Management Program 64 Charging Control Program 65 Charge / Discharge Curve Calculation Program 66 dQ / dV calculation program 67A 1st peak voltage calculation program 67B Second peak voltage calculation program 68A 1st shift calculation program 68B Second shift calculation program 69 Difference calculation program 70 Gas Generation Judgment Program 71 Operating condition control program 72 Notification Program

Claims

1. calculating a first dQ / dV curve from a first charge / discharge curve of the secondary battery; obtaining a first peak and a second peak of the first dQ / dV curve; calculating a second dQ / dV curve from a second charge / discharge curve of the secondary battery; obtaining a third peak and a fourth peak of the second dQ / dV curve; calculating a first shift amount from the first peak to the third peak and a second shift amount from the second peak to the fourth peak; determining whether gas is generated based on a difference between the first shift amount and the second shift amount; Including, Battery diagnostic methods.

2. 2. The battery diagnosis method according to claim 1, wherein the second charge / discharge curve is calculated according to charge / discharge cycles and / or elapsed time.

3. controlling an upper limit voltage and / or a lower limit voltage of an operating condition of the secondary battery based on the determination of the generation of gas; further comprising:

3. The battery diagnostic method according to claim 1 or 2.

4. notifying the occurrence of gas based on the determination of the occurrence of gas; further comprising: The battery diagnostic method according to claim 1 or 2.

5. The positive electrode of the secondary battery is LiNi ｘ Co ｙ Mn （１－ｘ－ｙ） O ２ (x is 0.5 or more and 0.9 or less, y is 0.05 or more and 0.45 or less, 1-x-y>0) 3. The battery diagnostic method according to claim 1 or 2.

6. The negative electrode of the secondary battery is lithium titanate, niobium titanium oxide, niobium oxide, or carbon; 3. The battery diagnostic method according to claim 1 or 2.

7. calculating a first dQ / dV curve from a first charge / discharge curve of the secondary battery; obtaining a first peak and a second peak of the first dQ / dV curve; calculating a second dQ / dV curve from a second charge / discharge curve of the secondary battery; obtaining a third peak and a fourth peak of the second dQ / dV curve; calculating a first shift amount from the first peak to the third peak and a second shift amount from the second peak to the fourth peak; determining whether gas is generated based on a difference between the first shift amount and the second shift amount; processing circuitry; Information processing device.

8. The information processing device according to claim 7; the secondary battery controlled by the information processing device, Battery system.

9. a user interface that can output information related to the information processing of the secondary battery or can input information related to the information processing of the secondary battery; The battery system according to claim 8 .

10. The processing circuit calculating a first dQ / dV curve from a first charge / discharge curve of the secondary battery; obtaining a first peak and a second peak of the first dQ / dV curve; calculating a second dQ / dV curve from a second charge / discharge curve of the secondary battery; obtaining a third peak and a fourth peak of the second dQ / dV curve; calculating a first shift amount from the first peak to the third peak and a second shift amount from the second peak to the fourth peak; determining whether gas is generated based on the difference between the first shift amount and the second shift amount; program.

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