Method for measuring amount of suppliable power, method for manufacturing power storage element, measurement device, and computer program

Abstract

In the present invention, a computer is caused to perform processing for: acquiring performance change information on each power storage element by performing a charge / discharge cycle test at a set number of cycles while varying charge / discharge conditions for each power storage element; determining a charge / discharge condition for performing a charge / discharge cycle test at a larger number of cycles than the set number of cycles, on the basis of the acquired performance change information of each power storage element; and determining the amount of suppliable power of the power storage element by using the performance change information acquired by performing the charge / discharge cycle test under the determined charge / discharge condition for performing a charge / discharge cycle test at a larger number of cycles than the set number of cycles.

Description

Method for measuring the amount of power that can be supplied, method for manufacturing an energy storage element, measuring device, and computer program

[0001] The present invention relates to a method for measuring a supplyable amount of power, a method for manufacturing an energy storage element, a measuring device, and a computer program.

[0002] Energy storage devices such as lithium-ion secondary batteries have been used as power sources for mobile devices such as laptops and mobile phones, but in recent years they have come to be used in a wide range of fields, including as power sources for electric vehicles.

[0003] A technology has been proposed for estimating the state of such energy storage elements based on information such as charge and discharge history (see Patent Document 1). This technology uses information such as charge and discharge history to predict the lifespan of the energy storage elements.

[0004] JP 2013-89424 A

[0005] The above technology is intended to predict the lifespan of a storage element, but it cannot measure the amount of power that can be supplied from the beginning of the storage element's life (BOL: Beginning of Life) to the end of its life (EOL: End of Life).

[0006] The present disclosure aims to provide a measurement method for measuring the amount of power that can be supplied by an energy storage element, a manufacturing method for an energy storage element, a measurement device, and a computer program.

[0007] The method for measuring the amount of power that can be supplied in the present disclosure involves acquiring performance change information for each storage element obtained by conducting a charge / discharge cycle test for a set number of cycles with different charge / discharge conditions for each storage element, determining charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles based on the acquired performance change information for each storage element, and using the performance change information obtained by conducting a charge / discharge cycle test under the determined charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles, a process is performed by a computer to determine the amount of power that can be supplied by the storage element.

[0008] According to the above aspect, the amount of power that can be supplied by the power storage element can be measured.

[0009] FIG. 1 is a schematic diagram showing an example of the configuration of a measurement system that measures the amount of power that can be supplied by an energy storage device. FIG. 2 is a block diagram showing the internal configuration of the measurement device. FIG. 3 is a graph showing changes in performance of each energy storage device when a short-term cycle test is performed. FIG. 4 is an explanatory diagram explaining a method for determining charge / discharge conditions. FIG. 5 is a graph showing changes in performance of an energy storage device when a long-term cycle test is performed. FIG. 6 is a flowchart explaining the procedure of processing executed by the measurement device. FIG. 7 is an explanatory diagram explaining the configuration of a manufacturing system according to a second embodiment.

[0010] (1) The method for measuring the amount of power that can be supplied according to the present disclosure includes acquiring performance change information for each storage element obtained by conducting a charge / discharge cycle test for a set number of cycles under different charge / discharge conditions for each storage element, determining charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles based on the acquired performance change information for each storage element, and using the performance change information obtained by conducting a charge / discharge cycle test under the determined charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles, a process is performed by a computer to calculate the amount of power that can be supplied by the storage element.

[0011] In the present disclosure, the suppliable power of an energy storage device refers to the total amount of power that the energy storage device can supply from the beginning of life (BOL) to the end of life (EOL) of the energy storage device. The beginning of life of the energy storage device refers to the time when the energy storage device is manufactured or shipped, and the end of life refers to the time when the capacity retention rate of the energy storage device falls below a set value (e.g., 60% or less of the initial capacity). In the measurement method (1) above, charge / discharge conditions for a long-term cycle test (a charge / discharge cycle test until the end of life) are determined based on performance change information of the energy storage device when a short-term cycle test (a charge / discharge cycle test with a set number of cycles) of, for example, about 100 cycles is performed. In the measurement method of the present disclosure, long-term performance changes can be predicted based on the test results (performance change information) of the short-term cycle test, and based on the prediction results, charge / discharge conditions can be determined that achieve the desired suppliable power and complete the long-term cycle test as quickly as possible. In the measurement method of the present disclosure, a long-term cycle test is carried out using the charge / discharge conditions determined as described above, and the amount of power that can be supplied by the energy storage element can be determined from the obtained performance change information.

[0012] (2) In the measurement method described in (1) above, based on the performance change information obtained from the charge / discharge cycle test at the set number of cycles, the performance change of each storage element when a charge / discharge cycle test is performed at a number of cycles greater than the set number of cycles may be estimated, and based on the estimated performance change of each storage element, the charge / discharge conditions of the charge / discharge cycle test to be performed to determine the amount of power that can be supplied may be determined.

[0013] According to the measurement method (2) above, the charge / discharge conditions for carrying out the long-term cycle test are determined based on the results of the short-term cycle test.

[0014] (3) In the measurement method described in (1) or (2) above, among the charge / discharge conditions that achieve the set amount of available power supply, the charge / discharge conditions that allow the charge / discharge cycle test to be completed most quickly may be determined.

[0015] According to the measurement method (3) above, the charge / discharge conditions are determined so that the desired amount of available power can be achieved and the long-term cycle test can be completed as quickly as possible.

[0016] (4) In the measurement method according to any one of (1) to (3) above, the charge / discharge condition may be at least one of a charge rate and a discharge rate.

[0017] According to the measurement method (4) above, the charge / discharge conditions that can achieve the desired amount of available power and complete the long-term cycle test in the shortest time can be specified by the charge rate or discharge rate.

[0018] (5) In the measurement method according to any one of (1) to (3) above, the charge / discharge condition may be at least one of an upper limit and a lower limit of a charge voltage.

[0019] According to the measurement method (5) above, the charge / discharge conditions that can achieve the desired amount of available power and complete the long-term cycle test in the shortest time can be specified by the upper or lower limit of the charge voltage.

[0020] (6) The manufacturing method of the storage element disclosed herein acquires information on the amount of power that can be supplied by the storage element, measured using the measurement method described in any one of (1) to (5) above, and displays the acquired information on the amount of power that can be supplied on the storage element.

[0021] According to the manufacturing method (6) above, it is possible to manufacture an energy storage element that displays information about the amount of available power supply.

[0022] (7) The device for measuring the amount of power that can be supplied according to the present disclosure includes a processing unit, and the processing unit acquires performance change information for each storage element obtained by conducting a charge / discharge cycle test for a set number of cycles with different charge / discharge conditions for each storage element, determines charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles based on the acquired performance change information for each storage element, and calculates the amount of power that can be supplied by the storage element using the performance change information obtained by conducting a charge / discharge cycle test under the charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles that has been determined.

[0023] According to the measuring device of (7) above, the charge / discharge conditions that can achieve the desired amount of power that can be supplied and that will complete the long-term cycle test as quickly as possible are determined, and the long-term cycle test is carried out under the determined charge / discharge conditions, thereby making it possible to measure the amount of power that can be supplied by the storage element.

[0024] (8) The computer program disclosed herein is a computer program for causing a computer to execute a process of acquiring performance change information for each storage element obtained by conducting a charge / discharge cycle test for a set number of cycles with different charge / discharge conditions for each storage element, determining charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles based on the acquired performance change information for each storage element, and calculating the amount of power that can be supplied by the storage element using the performance change information obtained by conducting a charge / discharge cycle test under the charge / discharge conditions for conducting the charge / discharge cycle test for a number of cycles greater than the determined set number of cycles.

[0025] According to the computer program of (8) above, the charge / discharge conditions that can achieve the desired amount of power that can be supplied and that will complete the long-term cycle test as quickly as possible are determined, and the long-term cycle test is carried out under the determined charge / discharge conditions, thereby making it possible to measure the amount of power that can be supplied by the storage element.

[0026] The present invention will be described in detail below with reference to the drawings illustrating embodiments. (Embodiment 1) FIG. 1 is a schematic diagram illustrating an example of the configuration of a measurement system for measuring the amount of power that can be supplied by an energy storage device. The measurement system according to the embodiment includes energy storage devices 1A to 1D to be measured, a charge / discharge cycle test device 2, and a measurement device 3. The energy storage devices 1A to 1D are connected to the charge / discharge cycle test device 2. The example in FIG. 1 illustrates a state in which four energy storage devices 1A to 1D are simultaneously connected to the charge / discharge cycle test device 2. Alternatively, the energy storage devices 1A to 1D may be connected one by one in turn to the charge / discharge cycle test device 2, and a charge / discharge cycle test may be performed on each of them. The number of devices to be measured is not limited to four, as long as it is two or more.

[0027] Energy storage elements 1A to 1D are energy storage elements used as power sources for electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like. Energy storage elements 1A to 1D are battery cells formed from lithium-ion batteries. Alternatively, energy storage elements 1A to 1D may be chargeable and dischargeable battery cells such as all-solid-state batteries, lead batteries, redox flow batteries, zinc-air batteries, alkaline manganese batteries, lithium-sulfur batteries, sodium-sulfur batteries, silver-zinc oxide batteries, nickel-metal hydride batteries, and molten salt thermal batteries. Energy storage elements 1A to 1D may also be battery modules formed by connecting a plurality of battery cells.

[0028] In this embodiment, the energy storage devices 1A to 1D to be measured are energy storage devices of the same type that were manufactured or shipped around the same time. Although there may be individual differences among the energy storage devices 1A to 1D, those that do not have large differences in performance are selected.

[0029] The charge / discharge cycle test device 2 is an existing device that performs charge / discharge cycle tests on the energy storage elements 1A to 1D and measures performance changes of each of the energy storage elements 1A to 1D. The charge / discharge cycle test device 2 performs charge / discharge cycle tests under set charge / discharge conditions and measures time-series changes in capacity retention rate (the ratio of capacity after aging when the initial capacity is taken as 100%). The charge / discharge cycle test is preferably performed in an environment at a constant temperature.

[0030] A measuring device 3 is communicably connected to the charge / discharge cycle test device 2. The communication between the charge / discharge cycle test device 2 and the measuring device 3 may be wired or wireless.

[0031] The measuring device 3 is a device for measuring the amount of power that can be supplied by the energy storage elements 1A to 1D. The amount of power that can be supplied represents the total amount of power that can be supplied by the energy storage element from the beginning of life (BOL) to the end of life (EOL) of the energy storage element. The beginning of the life of the energy storage element represents the time when the energy storage element is manufactured or shipped, and the end of life represents the time when the capacity maintenance rate of the energy storage element falls below a set value (for example, below 60% of the initial capacity), which can be set arbitrarily by the manufacturer. The amount of power that can be supplied represents the amount of power that can be supplied by one energy storage element over its lifetime from BOL to EOL, and is therefore also called the lifetime power supply amount.

[0032] In order to measure the amount of power that can be supplied by the energy storage elements 1A to 1D, the measuring device 3 first acquires performance change information for each of the energy storage elements 1A to 1D from the charge / discharge cycle test device 2, the performance change information being obtained by conducting a charge / discharge cycle test for a set number of cycles under different charge / discharge conditions. The set number of cycles is a relatively small number, such as about 100 cycles. In this specification, a charge / discharge cycle test conducted for a set number of cycles (about 100 cycles) is referred to as a short cycle test.

[0033] The measuring device 3 determines the charge / discharge conditions for a charge / discharge cycle test with a number of cycles greater than the set number based on the performance change information of each of the energy storage devices 1A to 1D obtained in the short cycle test. The number of cycles greater than the set number refers to the number of cycles at which the energy storage devices 1A to 1D reach EOL (typically greater than 500 cycles, and sometimes greater than 10,000 cycles). In this specification, a charge / discharge cycle test with a number of cycles greater than that of the short cycle test is referred to as a long cycle test.

[0034] In the short cycle test, the charge / discharge conditions for each of the energy storage elements 1A-1D are different, and therefore the performance changes during this period differ between the energy storage elements 1A-1D. The measuring device 3 estimates the performance changes that will occur when the long cycle test is conducted, based on the performance change information for each of the energy storage elements 1A-1D in the short cycle test. Based on the estimated performance changes, the measuring device 3 determines the charge / discharge conditions that will achieve the desired amount of power supply and that will complete the long cycle test most quickly. The charge / discharge conditions determined by the measuring device 3 may be at least one of the charge rate and the discharge rate, or at least one of the upper and lower limits of the charge voltage.

[0035] The measuring device 3 causes the charge / discharge cycle test device 2 to perform a long-term cycle test under determined charge / discharge conditions, and determines the amount of power that can be supplied by the energy storage devices 1A to 1D based on performance change information obtained from the long-term cycle test. Because the energy storage devices 1A to 1D are the same type of energy storage devices manufactured or shipped around the same time, there is no difference in the amount of power that can be supplied except for individual differences. Therefore, the long-term cycle test may be performed on any one of the energy storage devices 1A to 1D.

[0036] In the embodiment, the charge / discharge cycle test apparatus 2 and the measurement apparatus 3 are separate entities. Alternatively, the charge / discharge cycle test apparatus 2 and the measurement apparatus 3 may be integrated. That is, the measurement apparatus 3 may perform a charge / discharge cycle test on the energy storage devices 1A to 1D, and may calculate the amount of available power supply based on the obtained performance change information.

[0037] In the following description, when there is no need to distinguish between the energy storage elements 1A to 1D, they will also be referred to as energy storage element 1.

[0038] 2 is a block diagram showing the internal configuration of the measuring device 3. The measuring device 3 is a dedicated or general-purpose computer, and includes a control unit 31, a storage unit 32, a communication unit 33, an operation unit 34, a display unit 35, and the like.

[0039] The control unit 31 is an arithmetic circuit including a CPU, a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The CPU included in the control unit 31 reads and executes various computer programs stored in the ROM or the storage unit 32, thereby controlling the operation of each hardware unit and realizing the function of measuring the amount of power that can be supplied by the energy storage element 1.

[0040] Alternatively, the control unit 31 may be any arithmetic circuit including multiple CPUs, a multi-core CPU, a GPU (Graphics Processing Unit), a microcomputer, a volatile or non-volatile memory, etc. The control unit 31 may also include functions such as a timer that measures the elapsed time from when an instruction to start measurement is given until when an instruction to end measurement is given, a counter that counts numbers, and a clock that outputs date and time information.

[0041] The memory unit 32 includes a storage device such as a hard disk or a flash memory. Various computer programs and data are stored in the memory unit 32. The computer programs stored in the memory unit 32 include a measurement program PG for causing a computer to execute a process for measuring the amount of power that can be supplied by the energy storage device 1. The data stored in the memory unit 32 includes various parameters used in the measurement program PG, data generated by the control unit 31, and the like.

[0042] The measurement program PG may be a single computer program or a group of programs consisting of multiple computer programs. The measurement program PG may be executed by multiple computers working together. The measurement program PG may partially use an existing library.

[0043] A computer program including the measurement program PG is provided by a non-transitory recording medium RM on which the computer program is readably recorded. The recording medium RM is a portable memory such as a CD-ROM, a USB memory, or an SD (Secure Digital) card. The control unit 31 reads the desired computer program from the recording medium RM using a reading device (not shown) and stores the read computer program in the memory unit 32. Alternatively, the computer program including the measurement program PG may be provided via communication.

[0044] The communication unit 33 includes a communication interface for communicating with the charge / discharge cycle test apparatus 2. The communication unit 33 is communicably connected to the charge / discharge cycle test apparatus 2, acquires various information including performance change information of the energy storage device 1 from the charge / discharge cycle test apparatus 2, and provides necessary instructions to the charge / discharge cycle test apparatus 2.

[0045] The operation unit 34 includes input devices such as a keyboard and a mouse and accepts operations by the user. The display unit 35 includes a display device such as a liquid crystal display and displays information to be notified to the user. Alternatively, the measurement device 3 may be configured to accept necessary operations via an external device such as a user terminal and transmit information to be notified to the user to the external device. In this case, the operation unit 34 and the display unit 35 do not need to be installed in the measurement device 3.

[0046] The measurement device 3 in this embodiment may be a single computer, or may be a computer system configured with multiple computers and peripheral devices, etc. The measurement device 3 may be a virtual machine whose entity is virtualized, or may be a cloud.

[0047] The procedure for measuring the amount of power that can be supplied using the measuring device 3 includes (1) a procedure for determining charge / discharge conditions through a short-term cycle test, and (2) a procedure for performing a long-term cycle test under the determined charge / discharge conditions to determine the amount of power that can be supplied by the storage element 1.

[0048] (1) Determination of Charging Conditions The charge / discharge cycle test apparatus 2 performs a short-term cycle test on each of the energy storage elements 1A to 1D under different charge / discharge conditions. The short-term cycle test is preferably performed by placing the energy storage elements 1A to 1D in a thermostatic chamber at 25°C. The measurement device 3 acquires performance change information for each of the energy storage elements 1A to 1D from the charge / discharge cycle test apparatus 2. The performance change information indicates the change over time in the capacity retention rate.

[0049] 3 is a graph showing the change in performance of each of energy storage elements 1A to 1D when a short-term cycle test was conducted. The horizontal axis of the graph represents the number of cycles, and the vertical axis represents the capacity retention rate. A performance change curve VA shown in the graph of FIG. 3 represents the change in the capacity retention rate when a short-term cycle test was conducted with the discharge rate (or charge rate) of energy storage element 1A set to 0.5 C.

[0050] An existing measurement method is used to measure the capacity retention rate. The charge / discharge cycle test apparatus 2 determines the discharge capacity (or charge capacity) of the energy storage device 1 by performing constant current discharge (or constant current charge) at a predetermined discharge rate (or charge rate) in each cycle. Alternatively, the charge / discharge cycle test apparatus 2 may perform constant current and constant voltage charge during charging, or may change the discharge rate or charge rate midway through the cycle. The discharge capacity represents the amount of electricity that can be extracted from the energy storage device 1 when it is discharged from a fully charged state at a predetermined discharge rate. The charge capacity represents the amount of electricity that can be stored in the energy storage device 1 when it is charged at a predetermined charge rate until it reaches a fully charged state. The measurement apparatus 3 determines the capacity retention rate by calculating the ratio to the initial discharge capacity (or charge capacity).

[0051] The same is true for the performance change curves VB to VD shown in the graph of Fig. 3. The performance change curve VB represents the change in the capacity change retention rate when, for example, the discharge rate (or charge rate) of energy storage element 1B is set to 1C and a short cycle test is performed. The performance change curve VC represents the change in the capacity change retention rate when, for example, the discharge rate (or charge rate) of energy storage element 1C is set to 2C and a short cycle test is performed. The performance change curve VD represents the change in the capacity change retention rate when, for example, the discharge rate (or charge rate) of energy storage element 1D is set to 4C and a short cycle test is performed.

[0052] In the example of Figure 3, the performance change curves are shown for the case where a short cycle test was performed while changing the discharge rate (or charge rate) of energy storage elements 1A to 1D from 0.5C to 4C, but the discharge rate (or charge rate) is not limited to 0.5C to 4C and can be set as appropriate. The charge / discharge conditions when performing a short cycle test are not limited to the discharge rate (or charge rate), and at least one of an upper limit and a lower limit of the charge voltage may be set. The upper limit of the charge voltage is set as appropriate to a value equal to or higher than 80% SOC (State of Charge), and the lower limit is set as appropriate to a value equal to or lower than 20% SOC.

[0053] In this embodiment, a configuration is adopted in which a change in capacity maintenance rate is measured as a change in performance of the energy storage element 1. Alternatively, any index that can be a deterioration index of the energy storage element 1, such as SOH (State of Health), maximum charge / discharge current, maximum charge / discharge power amount, energy density, or internal resistance value, may be used as a change in performance of the energy storage element 1.

[0054] In this embodiment, the charge / discharge cycle test apparatus 2 is configured to measure performance changes of the energy storage device 1. In this case, the charge / discharge cycle test apparatus 2 acquires time-series data of current, voltage, etc. measured for the energy storage device 1, and calculates performance changes based on the acquired time-series data. Alternatively, if the energy storage device 1 includes a BMU (Battery Management Unit), performance changes may be measured in time series in the BMU.

[0055] The measuring device 3 determines the charge / discharge conditions for carrying out the long-term cycle test based on the performance changes of the energy storage devices 1A to 1D obtained in the short-term cycle test.

[0056] FIG. 4 is an explanatory diagram illustrating a method for determining charge / discharge conditions. The horizontal axis of the graph in FIG. 4 represents the number of cycles, and the vertical axis represents the capacity retention rate. In the graph in FIG. 4, the solid lines represent the performance changes of each of the energy storage elements 1A to 1D measured in the short-term cycle test, and the dashed lines represent the long-term performance changes estimated therefrom. The solid lines are obtained by actual measurements in the short-term cycle test, as described in FIG. 3. The measuring device 3 estimates the long-term performance changes by extrapolating the performance change curves VA to VD (solid lines) of each of the energy storage elements 1A to 1D obtained in the short-term cycle test. An existing method is used for the extrapolation. The measuring device 3 approximates the performance change curves VA to VD of the solid lines with appropriate approximation formulas, and estimates the performance changes of the dashed lines using the obtained approximation formulas.

[0057] Assume that the estimated results shown in Figure 4 are obtained by extrapolating the performance change curve actually measured in the short cycle test. The measurement device 3 determines the charge / discharge conditions for conducting the long cycle test based on the estimated results. Specifically, the measurement device 3 determines the charge / discharge conditions that will achieve the desired amount of available power and allow the long cycle test to be completed in the shortest time possible.

[0058] In this embodiment, the charge / discharge rate (at least one of the charge rate and the discharge rate) is set as the charge / discharge condition, and the higher the charge / discharge rate is set, the sooner the long-term cycle test should be completed. If the cycle test is performed with a high charge / discharge rate, the deterioration of the energy storage device 1 will progress at a faster rate, and there is a possibility that the desired amount of available power supply will not be achieved. Therefore, in this embodiment, a threshold value TH is set for the capacity retention rate at a specific number of cycles n (e.g., n = 500), and the highest charge / discharge rate at which the estimated value of the capacity retention rate at that number of cycles n exceeds the threshold value TH is adopted as the charge / discharge condition.

[0059] In the example of FIG. 4 , the estimated values ​​of the capacity retention ratio at the nth cycle exceed the threshold value TH for the discharge rates of 0.5C, 1C, and 2C, but the estimated value of the capacity retention ratio at the nth cycle does not exceed the threshold value TH for the discharge rate of 4C. Therefore, the 4C discharge rate is excluded from the charge / discharge conditions. If the highest discharge rate of 2C is adopted among the discharge rates of 0.5C, 1C, and 2C, the long-term cycle test can be completed most quickly. Therefore, the 2C discharge rate is adopted as the charge / discharge condition.

[0060] When the measuring device 3 determines a discharge rate of 2C as the charge / discharge condition, it instructs the charge / discharge cycle test device 2 to set the discharge rate to 2C and conduct a long-term cycle test. The long-term cycle test is performed on the energy storage element 1C, for which the discharge rate was set to 2C in the short-term cycle test. If 100 cycles of the short-term cycle test have been completed, the charge / discharge cycle test device 2 may conduct the long-term cycle test from the 101st cycle onward. Alternatively, the charge / discharge cycle test device 2 may set the discharge rate to 2C and conduct the long-term cycle test from the first cycle on a new energy storage element (of the same type that was manufactured or shipped at the same time as the energy storage elements 1A to 1D). The long-term cycle test is preferably performed by placing the energy storage elements 1A to 1D in a constant temperature bath at, for example, 25°C, similar to the short-term cycle test.

[0061] (2) Measurement of Suppliable Amount of Power The charge / discharge cycle test apparatus 2 performs a long-term cycle test under the charge / discharge conditions determined by the measurement apparatus 3. FIG. 5 is a graph showing the performance change of the energy storage element 1C when the long-term cycle test is performed. The horizontal axis of the graph represents the number of cycles, and the vertical axis represents the capacity retention rate. The performance change curve VC shown in the graph of FIG. 5 represents the change (actual measurement) in the capacity retention rate when the long-term cycle test is performed with the discharge rate of the energy storage element 1C set to 2C.

[0062] The long-term cycle test is performed until the energy storage device 1C reaches EOL (i.e., until the capacity maintenance rate falls below a set value). The set value for the capacity maintenance rate is, for example, 60%. When the long-term cycle test is completed, the measuring device 3 acquires the test results from the charge / discharge cycle test device 2 and calculates the amount of power that can be supplied by the energy storage device 1C based on the acquired test results. Specifically, the measuring device 3 calculates the amount of power that can be supplied based on the following equation 1.

[0063]

[0064] E on the left side total is the amount of available power to be calculated, and E on the right side n cycle is the amount of power per cycle, ε n is the power energy maintenance rate per cycle, and n is the number of cycles when the EOL is reached. When the energy storage element 1 to be measured is a battery cell, the measuring device 3 may calculate the amount of power that can be supplied when modularized or packed by multiplying the amount of power that can be supplied for the battery cell by the number of cells when modularized or packed. The energy storage element 1 may be measured in a modularized or packed state.

[0065] 6 is a flowchart illustrating the procedure of the process executed by the measuring device 3. The control unit 31 of the measuring device 3 sets different charge and discharge conditions for each of the plurality of energy storage elements 1 and instructs the charge and discharge cycle test device 2 to perform a short cycle test (step S101).

[0066] The charge / discharge cycle test apparatus 2 performs a cycle test a set number of times (e.g., 100 times) under set charge / discharge conditions. The cycle test is, for example, a constant current discharge test (or a constant current charge test). The charge / discharge cycle test apparatus 2 performs the constant current discharge test (or a constant current charge test) by controlling the charge and discharge of each storage element 1. At this time, the charge / discharge cycle test apparatus 2 measures the current, voltage, etc. of each storage element 1 in chronological order and calculates the capacity retention rate of each storage element 1 for each cycle. The charge / discharge cycle test apparatus 2 may calculate the power value of each storage element 1 for each cycle along with the capacity retention rate of each storage element 1 for each cycle.

[0067] The control unit 31 of the measuring device 3 communicates with the charge-discharge cycle test device 2 via the communication unit 33 and acquires performance change information of each energy storage element 1 obtained in the short cycle test (step S102). The performance change information includes the capacity maintenance rate of each energy storage element 1 for each cycle. The control unit 31 may acquire the performance change information for each cycle, or may acquire the performance change information for each cycle after the short cycle test is completed.

[0068] The control unit 31 determines charge / discharge conditions for conducting the long cycle test based on the performance change information acquired in step S102 (step S103). The control unit 31 estimates performance changes of each storage element 1 in the long cycle test based on the performance change information of each storage element 1 in the short cycle test. Based on the estimated performance changes of each storage element 1 in the long cycle test, the control unit 31 determines, as the charge / discharge conditions to be applied to the long cycle test, the charge / discharge conditions under which the charge / discharge cycle test is completed most quickly, among the charge / discharge conditions that can achieve the set available power supply amount,

[0069] The control unit 31 instructs the charge / discharge cycle test device 2 to carry out a long-term cycle test under the charge / discharge conditions determined in step S103 (step S104).

[0070] The charge / discharge cycle test apparatus 2 performs a long-term cycle test under the determined charge / discharge conditions until the energy storage elements 1 reach their end of life. The subjects of the long-term cycle test are energy storage elements 1 that have been subjected to a short-term cycle test under the above charge / discharge conditions. Alternatively, the subjects of the long-term cycle test may be brand new energy storage elements 1 that have not undergone a cycle test. The charge / discharge cycle test apparatus 2 measures the current, voltage, etc. of each energy storage element 1 in chronological order, and calculates the capacity retention rate of each energy storage element 1 for each cycle. The charge / discharge cycle test apparatus 2 may calculate the power value of each energy storage element 1 for each cycle along with the capacity retention rate of each energy storage element 1 for each cycle.

[0071] The control unit 31 communicates with the charge / discharge cycle test apparatus 2 via the communication unit 33 and acquires performance change information of the energy storage elements 1 obtained in the long-term cycle test (step S105). The performance change information includes the capacity maintenance rate of each energy storage element 1 for each cycle. The performance change information may further include the power value of each energy storage element 1 for each cycle. The control unit 31 may acquire the performance change information for each cycle, or may acquire the performance change information for each cycle after the long-term cycle test is completed.

[0072] When the long-term cycle test is completed in the charge-discharge cycle test apparatus 2, the control unit 31 calculates the amount of available power supply based on the performance change information (the capacity maintenance rate and the power value for each cycle) of the energy storage device 1 obtained in the long-term cycle test (step S106). The calculation method used is the method shown in Equation 1.

[0073] The control unit 31 outputs information about the calculated amount of available power supply (step S107). The control unit 31 causes the display unit 35 to display information indicating that the calculated amount of available power supply for the energy storage element 1 is XX (kWh). XX is the numerical value obtained by the calculation in step S106. Alternatively, the control unit 31 notifies the user's terminal device via the communication unit 33 of the information indicating that the calculated amount of available power supply for the energy storage element 1 is XX (kWh).

[0074] As described above, in the embodiment, the charge / discharge conditions that achieve the desired amount of power that can be supplied while completing the long-term cycle test in the shortest time are selected, and the long-term cycle test is performed under those charge / discharge conditions, thereby making it possible to determine the amount of power that can be supplied by the storage element 1.

[0075] Conventionally, long-term cycle tests have been conducted to measure the amount of power that can be supplied by the energy storage device 1, but depending on the charge and discharge conditions, the results may not be able to achieve the desired amount of power that can be supplied. For this reason, conventionally, in order to actually measure the amount of power that can be supplied by the energy storage device 1, it was necessary to conduct long-term cycle tests by changing the charge and discharge conditions in various ways, which took a very long time.

[0076] In contrast, in the present embodiment, it is possible to select charge / discharge conditions that achieve the desired amount of suppliable power while completing the long-term cycle test in the shortest time possible, thereby shortening the time required to actually measure the amount of suppliable power.

[0077] Second Embodiment In a second embodiment, an explanatory diagram is provided to explain a method for manufacturing an energy storage device 1 that displays information about the amount of available power supply.

[0078] 7 is an explanatory diagram illustrating the configuration of a manufacturing system according to embodiment 2. The manufacturing system according to embodiment 2 includes a measuring device 3 and a manufacturing device 4. As described in embodiment 1, the measuring device 3 measures the amount of power that can be supplied by the energy storage device 1. The measuring device 3 outputs information about the measured amount of power that can be supplied by the energy storage device 1 to the manufacturing device 4.

[0079] The manufacturing device 4 acquires information on the amount of power that can be supplied by the energy storage device 1 from the measuring device 3, and manufactures the energy storage device 1 on which the information on the amount of power that can be supplied is displayed. The manufacturing device 4 can manufacture the energy storage device 1 on which the information on the amount of power that can be supplied is displayed by attaching the label 11 on which the information on the amount of power that can be supplied is recorded to the energy storage device 1. The energy storage device 1 on which the information on the amount of power that can be supplied is displayed can be a battery cell, as well as a modularized or packaged device.

[0080] The location where the label 11 is attached can be determined arbitrarily. The label 11 may be attached to an exterior portion of the energy storage element 1 in a location that is visible to a user. The label 11 may record the value (numerical value) of the available energy supply, or may record a uniform resource locator (URL) that links to a site on a communication network that provides information on the available energy supply using a one-dimensional or two-dimensional code. In the latter case, a user can obtain information on the available energy supply by reading the label 11 (two-dimensional code) using a terminal device such as a smartphone and accessing the site specified by the URL. The label may also record information that the value of the available energy supply is an actually measured value.

[0081] As described above, in the second embodiment, it is possible to manufacture the energy storage device 1 that displays information on the amount of available power supply.

[0082] The disclosed embodiments are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims.

[0083] REFERENCE SIGNS LIST 1 Energy storage element 2 Charge / discharge cycle test device 3 Measuring device 31 Control unit 32 Storage unit 33 Communication unit 34 Operation unit 35 Display unit PG Measurement program RM Recording medium

Claims

1. A method for measuring the amount of suppliable electric power, which comprises the steps of: acquiring performance change information for each storage element obtained by conducting a charge / discharge cycle test for a set number of cycles under different charge / discharge conditions for each storage element; determining charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles based on the acquired performance change information for each storage element; and calculating the amount of suppliable electric power of the storage element using the performance change information obtained by conducting a charge / discharge cycle test under the charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles.

2. The measurement method according to claim 1, wherein the computer executes the following process: based on the performance change information obtained from the charge / discharge cycle test with the set number of cycles, estimate the performance change of each storage element when a charge / discharge cycle test with a number of cycles greater than the set number of cycles is performed; and based on the estimated performance change of each storage element, determine the charge / discharge conditions for the charge / discharge cycle test to be performed to determine the amount of available power supply.

3. The measurement method according to claim 1 or 2, wherein the computer executes a process of determining the charge / discharge conditions that will complete the charge / discharge cycle test most quickly from among the charge / discharge conditions that will achieve the set amount of available power supply.

4. The measurement method according to claim 1, wherein the charge / discharge condition is at least one of a charge rate and a discharge rate.

5. The measurement method according to claim 1, wherein the charge / discharge condition is at least one of an upper limit and a lower limit of a charge voltage.

6. A manufacturing method for an energy storage element, comprising: an apparatus for manufacturing an energy storage element, which acquires information on the amount of available power supply of the energy storage element measured using the measurement method set forth in any one of claims 1 to 5; and displays the acquired information on the amount of available power supply on the energy storage element.

7. A device for measuring the amount of suppliable electric energy, comprising a processing unit, which acquires performance change information for each storage element obtained by conducting a charge / discharge cycle test for a set number of cycles with different charge / discharge conditions for each storage element, determines charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles based on the acquired performance change information for each storage element, and calculates the amount of suppliable electric energy of the storage element using the performance change information obtained by conducting a charge / discharge cycle test under the charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles that has been determined.

8. A computer program for causing a computer to execute the following process: acquiring performance change information for each storage element obtained by conducting a charge / discharge cycle test for a set number of cycles under different charge / discharge conditions for each storage element; determining charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles based on the acquired performance change information for each storage element; and calculating the amount of power that can be supplied by the storage element using the performance change information obtained by conducting a charge / discharge cycle test under the charge / discharge conditions for conducting a charge / discharge cycle test for a number of cycles greater than the set number of cycles that has been determined.

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