JP6638227B2 - Power storage element deterioration state estimation device, storage element deterioration state estimation method, and power storage system - Google Patents

Description

  The present invention relates to a storage element deterioration state estimation device for estimating a deterioration state of a storage element, a storage element deterioration state estimation method, and a power storage system including the storage element and the storage element deterioration state estimation device.

  Power storage elements such as lithium ion secondary batteries have been used as power supplies for mobile devices such as notebook computers and mobile phones, but in recent years have been used in a wide range of fields such as power supplies for electric vehicles. Conventionally, a technique has been proposed for estimating the state of deterioration of such a storage element such as the amount of capacity reduction (for example, see Patent Document 1).

JP 2013-68458 A

However, in the above-described conventional technology, when a storage element using SiO _x (0.5 ≦ x ≦ 1.5) which is a silicon oxide as an active material of a negative electrode is targeted, the deterioration of the storage element is considered. There is a problem that the accuracy of estimating the state is low.

  That is, in the above-described conventional technique, graphite is generally used as the active material of the negative electrode, and the deterioration state of the power storage element is estimated on the premise of this. However, the inventors of the present application have as a result of intensive studies and experiments, when silicon oxide is used as the active material of the negative electrode, since it shows a different degradation state from the case of graphite, the same method as in the case of graphite is used. And found that the estimation accuracy decreases.

  For example, in Patent Document 1, in a battery using graphite (graphite) as an active material of a negative electrode, there is a correlation between the amount of decrease in dQ / dV and the amount of decrease in capacity at a peak appearing at 3.2 to 3.5 V during charging. There has been disclosed a technique in which the amount of capacity reduction can be estimated by this. However, when silicon oxide is used as the negative electrode active material, such a peak is not observed between 3.2 and 3.5 V, and it is not possible to estimate the amount of capacity reduction using this method. Can not.

  The present invention has been made in order to solve the above problem, and is intended for a storage element using silicon oxide as an active material of a negative electrode, and can improve the estimation accuracy of a deterioration state of the storage element. An object of the present invention is to provide an element deterioration state estimating device, a power storage element deterioration state estimating method, and a power storage system.

In order to achieve the above object, a storage element deterioration state estimation device according to one embodiment of the present invention is a storage element deterioration state estimation device that estimates a deterioration state of a storage element having a positive electrode, a negative electrode, and a nonaqueous electrolyte. , For a power storage element having a negative electrode including a negative electrode active material containing silicon oxide (SiO _x ), in a predetermined voltage range when the power storage element is discharged, capacity change data indicating a change in capacity with respect to a voltage. And an estimating unit for estimating the state of deterioration of the power storage device using the acquired capacitance change data, wherein the acquiring unit is configured to operate at the end of discharge when the potential of the negative electrode is equal to or higher than a predetermined potential. A voltage range is set to the predetermined voltage range, and the capacitance change data in the voltage range is acquired.

  Here, as a result of intensive studies and experiments, the inventors of the present application have found that when a storage element using silicon oxide as a negative electrode active material is discharged, a predetermined voltage range at the end of discharge when the potential of the negative electrode is equal to or higher than a predetermined potential It has been found that the capacitance change data indicating the amount of change in the capacitance with respect to the voltage characteristically changes. The inventors of the present application have found that the deterioration state of the power storage element can be accurately estimated by using the capacitance change data. Therefore, according to the power storage element deterioration state estimating device, it is possible to improve the accuracy of estimating the deterioration state of the power storage element for a storage element using silicon oxide as the negative electrode active material.

In addition, the acquisition unit sets a voltage range at the end of discharge in which the potential of the negative electrode is 0.6 V (vs. Li ^/ Li ⁺ ) or more as the predetermined voltage range, and acquires the capacitance change data in the voltage range. It may be.

Here, as a result of intensive studies and experiments, the present inventors have found that the capacity change data characteristically changes in the voltage range at the end of discharge where the potential of the negative electrode is 0.6 V (vs. Li ^/ Li ⁺ ) or higher. I found something to go. Therefore, according to the storage element deterioration state estimating device, the deterioration state of the storage element can be accurately estimated by acquiring the capacitance change data in the voltage range.

  Further, the obtaining unit further obtains a capacity maintenance ratio of the power storage element corresponding to the capacity change data, and the estimating unit uses the relationship between the capacity change data and the capacity maintenance ratio to calculate the power storage rate. The deterioration state of the element may be estimated.

  Here, as a result of earnest studies and experiments, the present inventors have found that the deterioration state of the power storage element can be accurately estimated by using the relationship between the capacity change data and the capacity maintenance rate. For this reason, according to the power storage element deterioration state estimating device, the accuracy of estimating the deterioration state of the power storage element can be improved.

  The estimating unit may determine that the storage element has reached the end of its life when the value of the capacity change data with respect to the capacity maintenance ratio is out of a predetermined range.

  Here, as a result of intensive studies and experiments, the inventors of the present application have found that when the value of the capacitance change data with respect to the capacitance retention ratio deviates from a predetermined range, it can be determined that the storage element has reached the end of its life. . For this reason, according to the power storage element deterioration state estimating apparatus, the life of the power storage element can be estimated by making the determination.

  In addition, the acquisition unit may acquire the capacitance change data for the negative-electrode limited storage device whose capacity is limited by a negative electrode.

  Here, as a result of earnest studies and experiments, the inventors of the present application have found that it is possible to accurately estimate the deterioration state of the power storage element for a negative electrode-limited power storage element. For this reason, according to the power storage element deterioration state estimating device, the accuracy of estimating the deterioration state of the power storage element can be improved.

  The present invention can be realized not only as such a storage element deterioration state estimation device, but also as a power storage system including a storage element and a storage element deterioration state estimation device that estimates a deterioration state of the storage element. can do. Further, the present invention can also be realized as a power storage element deterioration state estimation method in which characteristic processing performed by the power storage element deterioration state estimation device is performed as steps. Further, the present invention can also be realized as an integrated circuit including a characteristic processing unit included in the storage element deterioration state estimation device. In addition, the present invention can be realized as a program for causing a computer to execute characteristic processing included in the method for estimating a deterioration state of a storage element, or a computer-readable CD-ROM (Compact Disc-Read Only Memory) on which the program is recorded. ) Can be realized as a recording medium. Such a program can be distributed via a recording medium such as a CD-ROM and a transmission medium such as the Internet.

  ADVANTAGE OF THE INVENTION According to the storage element deterioration state estimation apparatus which concerns on this invention, the estimation accuracy of the deterioration state of the said storage element can be improved for the storage element using a silicon oxide as a negative electrode active material.

1 is an external view of a power storage system including a power storage element deterioration state estimation device according to an embodiment of the present invention. 1 is a block diagram showing a functional configuration of a storage element deterioration state estimation device according to an embodiment of the present invention. It is a figure showing an example of the data for estimation concerning an embodiment of the invention. 5 is a flowchart illustrating an example of a process in which the storage element deterioration state estimation device according to the embodiment of the present invention estimates a deterioration state of the storage element. 6 is a flowchart illustrating an example of a process in which an estimation unit according to the embodiment of the present invention estimates a deterioration state of a storage element. 5 is a graph illustrating a relationship between a capacity and a voltage when a storage element is charged and discharged. 4 is a graph illustrating a relationship between a capacity and a negative electrode potential when a storage element is charged and discharged. 5 is a graph showing the relationship between the voltage and the capacitance change data when the storage element is charged and discharged. 4 is a graph showing the relationship between the number of cycles and the capacity retention ratio when charging / discharging a storage element. 5 is a graph illustrating a relationship between a capacity retention ratio and capacity change data when a storage element is charged and discharged. 5 is a graph showing the relationship between the voltage and the capacitance change data when the storage element is charged and discharged. 5 is a graph illustrating a relationship between a capacity retention ratio and capacity change data when a storage element is charged and discharged. 9 is a flowchart illustrating another example of a process in which the estimation unit according to the embodiment of the present invention estimates a deterioration state of a storage element. 4 is a graph showing a relationship between a discharge capacity and a voltage when a power storage element using graphite as a negative electrode is charged and discharged. 4 is a graph showing a relationship between a discharge capacity and a voltage when a power storage element using SiO _x for a negative electrode is charged and discharged. 4 is a graph showing a relationship between a discharge capacity and a voltage when a power storage element using SiO _x for a negative electrode is charged and discharged. 5 is a graph illustrating a relationship between a capacity retention ratio and capacity change data when a storage element is charged and discharged. FIG. 2 is a block diagram illustrating a configuration in which the storage element deterioration state estimation device according to the embodiment of the present invention is implemented by an integrated circuit.

  Hereinafter, a power storage element deterioration state estimation device according to an embodiment of the present invention and a power storage system including the power storage element deterioration state estimation device will be described with reference to the drawings. The embodiment described below shows a specific example of the present invention. Numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of constituent elements, steps, order of steps, and the like shown in the following embodiments are merely examples, and do not limit the present invention. In addition, among the components in the following embodiments, components not described in the independent claims indicating the highest concept are described as arbitrary components.

  First, the configuration of the power storage system 10 will be described.

  FIG. 1 is an external view of a power storage system 10 including a power storage element deterioration state estimation device 100 according to an embodiment of the present invention.

  As shown in the figure, the power storage system 10 includes a power storage element deterioration state estimating device 100, a plurality of (five in the figure) power storage elements 200, a power storage element deterioration state estimating device 100, and the plurality of power storage elements 200. And a housing case 300 for housing. That is, one storage element deterioration state estimation device 100 is arranged corresponding to the plurality of storage elements 200.

  Power storage element deterioration state estimating apparatus 100 is a flat circuit board on which a circuit for estimating the deterioration state of power storage element 200 is mounted, and is disposed in a central portion above the plurality of power storage elements 200. Specifically, the storage element deterioration state estimation device 100 is connected to the plurality of storage elements 200, acquires information from the plurality of storage elements 200, and estimates the deterioration state of the plurality of storage elements 200. I do.

  Here, power storage element deterioration state estimating apparatus 100 is arranged at the central portion above power storage element 200, but power storage element deterioration state estimating apparatus 100 may be arranged anywhere. Further, the shape of power storage element deterioration state estimation device 100 is not particularly limited.

  The number of the storage element deterioration state estimating devices 100 is not limited, and may be a plurality. That is, one storage element deterioration state estimation device 100 may be arranged corresponding to a plurality of storage elements other than five or one storage element 200, or a plurality of storage element 200 may be corresponding to one storage element 200. The storage element deterioration state estimation device 100 may be provided. That is, any number of storage elements 200 may be connected to any number of storage element deterioration state estimation devices 100. The detailed functional configuration of the storage element deterioration state estimation device 100 will be described later.

  The storage element 200 is a secondary battery that can charge and discharge electricity, and more specifically, is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. In FIG. 5, five rectangular storage elements 200 are arranged in series to form a battery pack. Note that the number of power storage elements 200 is not limited to five, and may be another number or one. In addition, the shape of the power storage element 200 is not particularly limited, and may be a columnar shape, an elongated columnar shape, or the like.

  The energy storage device 200 includes a container and electrode terminals (a positive electrode terminal and a negative electrode terminal) protruding from the container, and the inside of the container is connected to the electrode body and the electrode body and the electrode terminal. Current collectors (a positive electrode current collector and a negative electrode current collector) are provided, and a liquid such as an electrolytic solution (a non-aqueous electrolyte) is sealed. The electrode body is formed by winding a positive electrode, a negative electrode, and a separator. Note that the electrode body may be a stacked electrode body in which flat electrode plates are stacked instead of a wound electrode body.

  The positive electrode is, for example, an electrode plate in which a positive electrode active material layer is formed on a positive electrode substrate which is a long strip-shaped metal foil made of aluminum, an aluminum alloy, or the like. As the positive electrode active material used for the positive electrode active material layer, a known material can be appropriately used as long as it is a positive electrode active material capable of inserting and extracting lithium ions. For example, examples of the positive electrode active material include a transition metal oxide, a transition metal sulfide, a lithium transition metal composite oxide, and a lithium-containing polyanion metal composite compound. Examples of the transition metal oxide include manganese oxide, iron oxide, copper oxide, nickel oxide, and vanadium oxide. Examples of the transition metal sulfide include molybdenum sulfide and titanium sulfide. Examples of the lithium transition metal composite oxide include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, lithium nickel manganese composite oxide, and lithium nickel cobalt manganese composite oxide. No. Examples of the lithium-containing polyanion metal composite compound include lithium iron phosphate and lithium cobalt phosphate. Further, conductive polymer compounds such as disulfide, polypyrrole, polyaniline, polyparastyrene, polyacetylene, and polyacene-based materials, and carbonaceous materials having a pseudo-graphite structure may be used.

  Among these, the positive electrode active material may have a step-like discharge curve, but the present invention utilizes the change in the potential behavior of the negative electrode at the end of discharge, so that the battery discharge It is preferable to select a positive electrode active material in which the potential of the positive electrode does not change very complicatedly at the end. From this viewpoint, a positive electrode active material in which a discharge curve continuously changes or a flat portion is observed in a wide range is preferable. Examples of such a material include a lithium transition metal composite oxide having a layered structure and lithium iron phosphate having an olivine type crystal structure.

The negative electrode is, for example, an electrode plate in which a negative electrode active material layer is formed on a negative electrode substrate which is a long strip-shaped metal foil made of copper, a copper alloy, or the like. As the negative electrode active material used for the negative electrode active material layer, only SiO _x may be used, or a mixture of SiO _x and another negative electrode active material capable of inserting and extracting lithium ions may be used. Other negative electrode active materials used by mixing with SiO _x include graphite, hard carbon, soft carbon, and the like. Among these other active materials, graphite is preferable in that a charge / discharge potential is relatively low, so that a power storage element having a high energy density can be provided. The graphite used in admixture with SiO _x, scaly graphite, spherical graphite, artificial graphite, natural graphite, and the like. Above all, by selecting and using flaky graphite, it is easy to maintain contact with the SiO _x particle surface even after repeated charging and discharging, so that an energy storage device having excellent charge and discharge cycle performance can be easily provided. ,preferable. Mixing ratio of SiO _x and other anode active material is not limited. For example, as the negative electrode active material, a material in which SiO _x and flaky graphite are blended in a ratio of 8: 2 to 2: 8 can be used. Further, a conductive auxiliary such as acetylene black or Ketjen black may be included. The content of SiO _x in the negative electrode active material is not particularly limited, but is preferably about 5% by weight or more, and preferably about 10% by weight or more in order to exhibit the characteristics at the time of discharge described below. More preferably, there is. As the SiO _x particles, those having a surface coated with a carbon material in advance may be used. The SiO _x may be pre-doped with Li. The stage of predoping the SiO _x with Li may be any stage as long as it is before the first charge between the positive and negative electrodes. The negative electrode mixture may be formed by mixing Li with pre-doped SiO _x particles and other negative electrode active materials or binders.

  The separator is, for example, a microporous sheet made of a resin. Note that the separator used for the storage element 200 is not particularly different from that conventionally used, and a known material can be appropriately used as long as the performance of the storage element 200 is not impaired. The type of electrolyte (non-aqueous electrolyte) enclosed in the container is not particularly limited as long as the performance of the storage element 200 is not impaired, and various types can be selected.

  With the above configuration, power storage element 200 is a negative-electrode limited power storage element. Here, the negative-electrode-limited storage device is a storage device in which the capacity (particularly, discharge capacity) is limited by the negative electrode. Specifically, the negative electrode capacity is smaller than the positive electrode capacity (the capacity of the negative electrode active material is positive electrode capacity). (Less than the capacity of the active material).

  The storage element 200 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than the non-aqueous electrolyte secondary battery.

  Next, a detailed functional configuration of the storage element deterioration state estimation device 100 will be described.

  FIG. 2 is a block diagram showing a functional configuration of the storage element deterioration state estimation device 100 according to the embodiment of the present invention. FIG. 3 is a diagram illustrating an example of the estimation data 132 according to the embodiment of the present invention.

  The storage element deterioration state estimating apparatus 100 is an apparatus that estimates the deterioration state of the storage element 200. As illustrated in FIG. 2, the storage element deterioration state estimation device 100 includes an acquisition unit 110, an estimation unit 120, and a storage unit 130. Further, storage unit 130 is a memory for storing various data for estimating the deterioration state of power storage element 200, and stores charge / discharge history data 131 and estimation data 132.

Acquisition section 110 acquires capacitance change data indicating the amount of change in capacitance with respect to voltage in a predetermined voltage range when power storage element 200 is discharged. Further, acquisition section 110 acquires a capacity maintenance rate of power storage element 200 corresponding to the capacity change data. The storage element 200 from which the obtaining unit 110 obtains the capacity change data is, as described above, a storage element 200 having a negative electrode including a negative electrode active material containing silicon oxide (SiO _x ), and Is a negative-electrode-limited storage element 200 limited by a negative electrode.

  Specifically, acquisition section 110 is connected to power storage element 200, and detects and obtains a charge / discharge history from power storage element 200. That is, acquisition section 110 is electrically connected to the electrode terminal of power storage element 200 on which power storage element deterioration state estimating device 100 is mounted by wiring such as a lead wire. Then, the obtaining unit 110 obtains a charge / discharge history from the power storage element 200 via the wiring. The timing of acquiring the charge / discharge history is not particularly limited.

  Here, the charge / discharge history is an operation history of the storage element 200, information indicating a period (use period) during which the storage element 200 was charged or discharged, and a charge or discharge performed by the storage element 200 during the use period. This is information that includes information about

  The information indicating the usage period of the storage element 200 is a date (year, month, day) and time indicating information when the storage element 200 is charged or discharged, or a cumulative usage period in which the storage element 200 has been used. It is information including. The cumulative use period is a cumulative value of the use period of the storage element 200, and specifically indicates a period from the start of use of the storage element 200. The unit of the cumulative use period may be any unit indicating the period, such as time (hour, minute, second), day, month, or cycle (number of charge / discharge).

  The information on the charge or discharge performed by the storage element 200 is information indicating a voltage, a current, a battery state, and the like at the time of charge or discharge performed by the storage element 200. The battery state is information indicating an operation state of the storage element 200, such as a charged state, a discharged state, and a left state (a state in which neither charging nor discharging is performed). Note that when the battery state is estimated from the information indicating the voltage or current of the power storage element 200, the information indicating the battery state is unnecessary.

  Then, the acquisition unit 110 writes the acquired charge / discharge history to the charge / discharge history data 131 stored in the storage unit 130.

  Then, the acquisition unit 110 reads the voltage and current when the power storage element 200 is discharged from the charge / discharge history data 131, calculates the capacity (Q), and further calculates the capacity (Q) with respect to the voltage (V). The amount of change (dQ / dV) is calculated as capacitance change data. Then, the acquisition unit 110 acquires capacitance change data in a predetermined voltage range.

Here, the predetermined voltage range is a voltage range at the end of discharge in which the potential of the negative electrode is equal to or higher than the predetermined potential. That is, the acquisition unit 110 sets the voltage range at the end of discharge in which the potential of the negative electrode is equal to or higher than the predetermined potential as the above-described predetermined voltage range, and obtains the capacity change data in the voltage range. For example, the end of discharge occurs when the negative electrode potential is 0.6 V (vs. Li ^/ Li ⁺ ) or higher, and corresponds to a negative electrode potential of 0.6 V to 1.5 V (vs. Li ^/ Li ⁺ ). When the voltage range to be applied is 3.25 V to 2.4 V, the predetermined voltage range is 3.25 V to 2.4 V.

  In addition, the obtaining unit 110 obtains the capacity retention rate corresponding to the capacity change data obtained above by calculating the capacity maintenance rate of the power storage element 200 from the calculated capacity.

  Then, the acquisition unit 110 writes the acquired capacity change data and the capacity maintenance rate, the corresponding voltage, and the usage period (for example, date and time) to the estimation data 132 stored in the storage unit 130. Here, as shown in FIG. 3, the estimation data 132 is a data table in which “use period”, “voltage”, “capacity change data”, and “capacity maintenance rate” are associated with each other.

  The estimation unit 120 estimates the deterioration state of the storage element 200 using the capacity change data acquired by the acquisition unit 110. Specifically, estimating section 120 determines that power storage element 200 has reached the end of its life when the absolute value of the capacitance change data becomes smaller than a predetermined value.

  That is, the estimation unit 120 reads the capacity change data from the estimation data 132 and determines whether or not the absolute value of the capacity change data has become smaller than a predetermined value. Then, when determining that the absolute value of the capacitance change data has become smaller than the predetermined value, estimation section 120 determines that power storage element 200 has reached the end of its life.

  Further, estimation section 120 estimates the deterioration state of power storage element 200 using the capacity change data and the capacity maintenance rate acquired by acquisition section 110. That is, estimating section 120 estimates the deterioration state of power storage element 200 using the relationship between the capacity change data and the capacity maintenance rate. Specifically, estimating section 120 determines that power storage element 200 has reached the end of its life when the value of the capacity change data with respect to the capacity maintenance rate falls outside a predetermined range.

  That is, the estimation unit 120 reads the capacity change data and the capacity maintenance rate from the estimation data 132, and determines whether the value of the capacity change data with respect to the capacity maintenance rate is out of the predetermined range. Then, estimating section 120 determines that power storage element 200 has reached the end of its life when it is determined that the value of the capacity change data with respect to the capacity maintenance rate is out of the predetermined range.

  Next, the process in which power storage element deterioration state estimation device 100 estimates the deterioration state of power storage element 200 will be described in detail.

  FIG. 4 is a flowchart illustrating an example of a process in which power storage element deterioration state estimation device 100 according to the embodiment of the present invention estimates a deterioration state of power storage element 200.

As shown in the figure, the acquisition unit 110 targets a power storage element 200 having a negative electrode including a negative electrode active material containing silicon oxide (SiO _x ) and discharges the power storage element 200 in a predetermined voltage range. Then, capacitance change data indicating the amount of change in capacitance with respect to voltage is obtained (S102: obtaining step).

  Then, the estimation unit 120 estimates the deterioration state of the storage element 200 using the capacity change data acquired by the acquisition unit 110 (S104: estimation step). The process of estimating the deterioration state of power storage element 200 by estimating section 120 will be described in detail below.

  FIG. 5 is a flowchart illustrating an example of a process in which estimating section 120 according to the embodiment of the present invention estimates a deterioration state of power storage element 200.

  As shown in the drawing, the estimating unit 120 determines whether or not the absolute value of the capacity change data acquired by the acquiring unit 110 has become smaller than a predetermined value (S202).

  Then, when determining that the absolute value of the capacitance change data has become smaller than the predetermined value (YES in S202), estimation section 120 determines that power storage element 200 has reached the end of its life (S204). In addition, when determining that the absolute value of the capacitance change data is not smaller than the predetermined value (NO in S202), estimating section 120 determines that power storage element 200 has not reached its life yet ( S206).

  Here, the fact that the estimation unit 120 can make the determination as described above will be described in detail. 6 to 9B are diagrams illustrating an example of a process in which the estimation unit 120 according to the embodiment of the present invention estimates a deterioration state of power storage element 200.

  Specifically, FIG. 6 is a graph illustrating a relationship between the capacity and the voltage when the power storage element 200 is charged and discharged. In other words, in the figure, the horizontal axis indicates the capacitance and the vertical axis indicates the voltage, and the number of cycles is 25 ° C., 0.2 C at each time point after 0, 50, 150, 200, 300, 500, and 600 cycles. 3 shows a change in voltage with respect to the capacity at the time of discharging.

  FIG. 7A is a graph illustrating a relationship between the capacity and the negative electrode potential when the power storage element 200 is charged and discharged. That is, in the figure, the horizontal axis represents the capacity, and the vertical axis represents the negative electrode potential value. The cycle number is 0, 50, 150, 200, 300, 500 and 600. The change of the negative electrode potential with respect to the capacity at the time of discharging at 2C is shown.

  FIG. 7B is a graph showing a relationship between voltage and capacitance change data when power storage element 200 is charged and discharged. That is, in the figure, the horizontal axis shows the voltage and the vertical axis shows the value of the capacitance change data, and when the number of cycles is 0, 50, 150, 200, 300, 500, and 600 cycles, at 25 ° C., 0 2C shows a change in capacitance change data with respect to a voltage at the time of discharging at 2C.

Here, these drawings show the results of a test performed using the following storage element 200. That is, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , which is a kind of lithium transition metal composite oxide having a layered crystal structure, is used for the positive electrode active material as the storage element 200, and is used for the negative electrode active material. Used was a mixture of SiO: graphite in a ratio of 8: 2. As the electrode body, a laminated electrode body in which a plate-shaped positive electrode and a negative electrode were opposed to each other was used, and a battery having a rated capacity of 40 mAh was used. used. In FIGS. 8A to 9B, since the test is performed using the same storage element 200 as described above, the description of the storage element 200 in FIGS. 8A to 9B is omitted below.

  In the charge / discharge cycle test, charging was performed at a constant current and constant voltage with a charging current of 1C, and discharging was performed at a constant current with a discharge current of 1C. The temperature during the charge / discharge cycle test was 45 ° C. Note that the same test as described above is performed in FIGS. 8A to 9B described below, and a description of the test in FIGS. 8A to 9B will be omitted below.

First, as shown in FIG. 6, at the time of discharging of power storage element 200, the voltage rapidly changes (drops) at the end of discharge (portion A). As described above, the inventors of the present invention have conducted intensive studies and experiments and have found that in the electric storage device 200 using SiO _x for the negative electrode, not only does the capacity decrease with the charge / discharge cycle, but also, as shown in FIG. Has a characteristic that the shape at the end of discharge changes.

In addition, as shown in FIG. 7A, at the time of discharging of power storage element 200, the negative electrode potential sharply changes (rises) at the end of discharge (portion B). As described above, the inventors of the present invention have found that in the electric storage element 200 using SiO _x for the negative electrode, as shown in the figure, the curve shape at the end of discharging of the negative electrode characteristically changes with the charge / discharge cycle. 6 and that the characteristic shown in FIG. 6 appears due to the fact that the power storage element 200 is of the negative electrode limiting type.

Then, as shown in FIG. 7B, the inventors of the present application observed the change at the end of discharge of the capacity change data (portion C), and after 500 cycles, the degree of decrease in the capacity change data began to sharply occur. We found that such inflection points were clearly seen. That is, in a voltage (for example, 2.75 V) in a voltage range of 3.25 V to 2.4 V at the end of discharge where the negative electrode potential is 0.6 V (vs. Li ^/ Li ⁺ ) or more, the capacity increases with the number of cycles. The absolute value of the change data is decreasing.

  Accordingly, when the absolute value of the capacitance change data becomes smaller than a predetermined value, it can be determined that the storage element 200 has reached the end of its life. For example, since the absolute value of the capacitance change data sharply decreases after 500 cycles, if the predetermined value is set to about 4 to 5, the storage element 200 reaches the end of its life in 500 cycles. You can judge. The predetermined value is appropriately set depending on the timing of the life requested by the user (such as the value of the capacity maintenance ratio requested by the user).

  The predetermined value may be stored in advance in the estimation data 132, may be written in the estimation data 132 by a user's input, or the like, or may be calculated by the estimation unit 120 according to a predetermined condition. You can do it.

  Accordingly, when the estimation unit 120 determines that the absolute value of the capacitance change data has become smaller than the predetermined value, the estimation unit 120 can determine that the storage element 200 has reached the end of its life.

  Next, the fact that the estimation of the deterioration state of power storage element 200 performed by estimation section 120 does not depend on the charge / discharge range of power storage element 200 will be described.

  FIG. 8A is a graph showing the relationship between the number of cycles and the capacity retention ratio when the storage element 200 is charged and discharged. That is, in the figure, the horizontal axis indicates the number of cycles, and the vertical axis indicates the value of the capacity retention ratio, and charging and discharging were performed at DODs (Depth Of Discharge: 25, 50, 75, and 100%). The change of the capacity retention ratio with respect to the number of cycles in the case is shown. Note that, for example, charging / discharging at a DOD of 25% indicates that charging / discharging was repeatedly performed while the SOC (State Of Charge) was approximately 75% to 100%.

  FIG. 8B is a graph illustrating a relationship between the capacity retention ratio and the capacity change data when the power storage element 200 is charged and discharged. That is, in the figure, the horizontal axis indicates the capacity retention ratio, the vertical axis indicates the value of the capacity change data at a voltage of 2.75 V, and the DOD (Depth Of Discharge: depth of discharge) is 25, 50, 75 and 100%, respectively. In the case where the battery was charged and discharged under the conditions described above, at each time when a predetermined number of cycles had elapsed, the change in the capacity change data with respect to the capacity retention ratio when discharging to a predetermined voltage range at 25 ° C. and 0.2 C is shown. I have.

  That is, FIG. 8B shows the relationship between the capacity retention ratio and the capacity change data when charging and discharging are performed in various charging and discharging ranges as in FIG. 8A. In charging and discharging in any of the charging and discharging ranges, The capacity maintenance ratio and the capacity change data indicate a proportional relationship. As described above, a good proportional relationship was found between the capacity change data at 2.75 V and the capacity retention ratio regardless of the charge / discharge range of the power storage element 200. It can be seen that the state of deterioration of the storage element 200 can be estimated from the value of the data.

  Therefore, estimating section 120 determines that power storage element 200 has reached the end of its life when determining that the absolute value of the capacity change data has become smaller than a predetermined value regardless of the charge / discharge range of power storage element 200. be able to.

Here, the above-mentioned predetermined voltage range is preferably a voltage range at the end of discharge in which the potential of the negative electrode is 0.6 V (vs. Li ^/ Li ⁺ ) or more. In other words, the acquiring unit 110 sets the voltage range at the end of discharge in which the potential of the negative electrode is 0.6 V (vs. Li ^/ Li ⁺ ) or more as the above-described predetermined voltage range, and acquires the capacity change data in the voltage range. preferable. This will be described below.

Table 1 shows the case of changing the negative electrode potential, and numbers of R ² in the graph of FIG. 8B corresponding to the negative electrode potential, and a voltage of the storage element 200 (the battery voltage).

As shown in Table 1 above, in the case where the negative electrode potential is 0.6 V to 1.4 V (vs. Li / Li ⁺ ) (Examples 1 to 3), the value of R ² approaches 1, It can be seen from the graph of FIG. 8B that the capacity change data and the capacity maintenance ratio have a favorable proportional relationship. Therefore, estimation section 120 can accurately estimate the state of deterioration of power storage element 200 from the value of the capacitance change data. The predetermined voltage range in this case is 3.25 V to 2.5 V (Examples 1 to 3).

In addition, in the case where the negative electrode potential is 0.6 V to 1.2 V (vs. Li / Li ⁺ ) (Examples 2 and 3), since the value of R ² is closer to 1, in the graph of FIG. The capacity change data and the capacity maintenance ratio have a better proportional relationship. The predetermined voltage range in this case is 3.25 V to 2.75 V (Examples 2 and 3).

As described above, the above-mentioned predetermined voltage range is the voltage range (3.25 V or less 2.5 V or more) at the end of discharge when the potential of the negative electrode is 0.6 V or more and 1.4 V or less (vs. Li ^/ Li ⁺ ). It is more preferable that the potential of the negative electrode be in the range of from 0.6 V to 1.2 V (vs. Li ^/ Li ⁺ ) at the end of discharge (3.25 V to 2.75 V). Further, it is more preferable that the above-mentioned predetermined voltage range is such that the potential of the negative electrode is about 1.2 V (vs. Li ^/ Li ⁺ ) at the end of discharge (about 2.75 V).

  Next, the fact that the estimation of the deterioration state of power storage element 200 performed by estimating section 120 does not depend on the power supply rate and temperature of power storage element 200 will be described.

  FIG. 9A is a graph illustrating a relationship between the voltage and the capacitance change data when the electric storage element 200 is charged and discharged. In other words, in the figure, the horizontal axis indicates the voltage, and the vertical axis indicates the value of the capacitance change data, and the voltage at the time of discharge is 0, 50, 150, 200, 300, 500, and 600 cycles later, respectively. 5 shows a change in the capacitance change data with respect to.

  FIG. 9B is a graph illustrating a relationship between the capacity retention ratio and the capacity change data when the power storage element 200 is charged and discharged. That is, in the figure, the horizontal axis shows the capacity retention ratio, the vertical axis shows the value of the capacitance change data at a voltage of 2.75 V, and the number of cycles is 0, 50, 150, 200, 300, 500, and 600 cycles, respectively. Shows the change of the capacity change data with respect to the capacity maintenance rate at the time point.

  Here, in the tests in FIG. 6 to FIG. 8B, the power supply rate at the time of discharging the power storage device 200 at the time of data acquisition was 0.2 C, and the temperature was 25 ° C. On the other hand, in the tests in FIGS. 9A and 9B, the energization rate at the time of data acquisition at the time of data storage element 200 discharge is 1 C, and the temperature is 45 ° C.

  That is, FIG. 9B shows the relationship between the capacity retention ratio and the capacity change data when charging and discharging are performed at a current rate of 1 C and a temperature of 45 ° C. at various cycle numbers as in FIG. 9A. Also in charge and discharge, the capacity retention rate and the capacity change data show a proportional relationship, as in the case of the power supply rate of 0.2 C and the temperature of 25 ° C. As described above, a good proportional relationship was found between the capacity change data at 2.75 V and the capacity retention ratio regardless of the power supply rate and temperature of the power storage element 200. It can be seen that the deterioration state of the storage element 200 can be estimated from the value of the capacitance change data.

  For this reason, the estimating unit 120 determines that the storage element 200 has reached the end of its life when determining that the absolute value of the capacitance change data has become smaller than the predetermined value regardless of the energization rate and the temperature of the storage element 200. can do.

  As described above, the example of the process (S104 in FIG. 4) in which the estimation unit 120 estimates the deterioration state of the power storage element 200 ends.

  Next, another example of the process (S104 in FIG. 4) in which the estimation unit 120 estimates the deterioration state of the power storage element 200 will be described.

  FIG. 10 is a flowchart illustrating another example of a process in which estimating section 120 according to the embodiment of the present invention estimates a deterioration state of power storage element 200.

  As shown in the drawing, the obtaining unit 110 obtains the capacity maintenance ratio of the storage element 200 corresponding to the capacity change data (S302).

  Next, the estimating unit 120 determines whether or not the value of the capacity change data with respect to the capacity maintenance ratio is out of a predetermined range (S304).

  When the estimation unit 120 determines that the value of the capacity change data with respect to the capacity maintenance ratio is out of the predetermined range (YES in S304), it determines that the storage element 200 has reached the end of its life (S306). In addition, when determining that the value of the capacity change data with respect to the capacity maintenance ratio is not out of the predetermined range (NO in S304), the estimating unit 120 determines that the storage element 200 has not reached its life yet ( S308).

  As described above, estimation section 120 estimates the deterioration state of power storage element 200 using the relationship between the capacity change data and the capacity maintenance rate.

  Here, the fact that the estimation unit 120 can make the determination as described above will be described in detail. FIGS. 11A to 12 are diagrams for explaining another example of the process in which estimating section 120 according to the embodiment of the present invention estimates the deterioration state of power storage element 200.

  Specifically, FIG. 11A is a graph illustrating a relationship between a discharge capacity and a voltage when a power storage element using graphite as a negative electrode is charged and discharged. In other words, in this figure, the horizontal axis indicates the discharge capacity, and the vertical axis indicates the voltage value. At each time point after 0, 50, 150, 300, and 500 cycles, the change in the voltage with respect to the discharge capacity is shown. Is shown.

FIGS. 11B and 11C are graphs each showing a relationship between a discharge capacity and a voltage when the electric storage element 200 using SiO _x for the negative electrode is charged and discharged. In other words, in this figure, the horizontal axis indicates the discharge capacity, and the vertical axis indicates the voltage value. At each time point after 0, 50, 150, 300, and 500 cycles, the change in the voltage with respect to the discharge capacity is shown. Is shown.

FIG. 12 is a graph showing the relationship between the capacity retention ratio and the capacity change data when the storage element is charged and discharged. That is, FIG capacity retention ratio on the horizontal axis, the voltage on the vertical axis takes the value of the capacitance change data in 2.75 V, in case of using graphite and SiO _x to the negative electrode, the capacitance change data for the capacity retention rate The change is shown.

Here, these figures show the results of tests performed using the following storage elements. That is, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ is used as a positive electrode active material as a power storage element, and a flat wound electrode in which a positive electrode and a negative electrode are wound is used as an electrode body. A battery having a rated capacity of 900 mAh was used. In addition, as the negative electrode active material, graphite is used in FIG. 11A, a material mixed in a ratio of SiO: graphite (Gr) = 4: 6 in FIG. 11B, and SiO: graphite (Gr) is used in FIG. 11C. = 2: 8 was used. FIG. 12 shows a change in capacitance change data with respect to a capacity retention ratio for a power storage element using graphite and SiO _x for the negative electrode in FIGS. 11A to 11C.

As shown in FIG. 12, when SiO _x was used for the negative electrode, a proportional relationship (linearity) was observed between the capacity retention rate and the capacity change data at 2.75 V up to 150 cycles. However, after 300 cycles (capacity maintenance rate of 60% or less), the slope of the straight line up to 150 cycles deviates. This is because, as shown in FIG. 11B and FIG. 11C, in 300 cycles, the mode shifts to the degradation mode due to the electrolyte withering. As described above, if the storage element deviates from the straight line when the life of the storage element reaches the end of its life, from the transition of the value of the capacitance change data accumulated until the end of the life, the time point at which an abnormal value is shown is regarded as the life of the storage element. Can be diagnosed. On the other hand, when only graphite was used for the negative electrode, the capacity retention ratio and the capacity change data did not show a proportional relationship (linearity).

  Thus, when it is determined that the value of the capacitance change data (the slope of the straight line in FIG. 12) with respect to the capacitance retention ratio is out of the predetermined range, it can be determined that the storage element 200 has reached the end of its life. For example, after 300 cycles, if the value of the capacity change data (the slope of the straight line) with respect to the capacity maintenance ratio deviates by about ± 10 to 30% or more, the predetermined range is set to about ± 10 to 30%. If this is done, it can be determined that the storage element 200 has reached the end of its life in 300 cycles. This predetermined range is appropriately set according to the timing of the life requested by the user (such as the value of the capacity maintenance ratio requested by the user).

  The predetermined range may be stored in the estimation data 132 in advance, may be written in the estimation data 132 by a user's input, or the like, or may be calculated by the estimation unit 120 according to a predetermined condition. It doesn't matter.

  Thus, when the estimation unit 120 determines that the value of the capacity change data with respect to the capacity maintenance ratio is out of the predetermined range, the estimation unit 120 can determine that the storage element 200 has reached the end of its life.

  As described above, the other example of the process (S104 in FIG. 4) in which the estimation unit 120 estimates the deterioration state of the power storage element 200 ends.

As described above, according to the storage element deterioration state estimation device 100 according to the embodiment of the present invention, the deterioration of the storage element 200 is targeted for the storage element 200 using silicon oxide (SiO _x ) as the negative electrode active material. The state estimation accuracy can be improved.

That is, since the electrochemical reaction of the SiO _x negative electrode is considered to follow the formula of 4SiO + 17.2Li → 3Li _4.4 Si + Li ₄ SiO ₄ when x = 1, Li _4.4 Si was used as the charged active material. In this case, the initial charge / discharge efficiency is as low as 76.7%. Furthermore, the charge and discharge efficiency is lower in the second and subsequent charge / discharge cycles than in the graphite negative electrode. This is considered to be due to the slow generation reaction of Li ₄ SiO ₄ shown in the above formula. When the charge and discharge cycle is repeated, in addition to the accumulation of irreversible capacity due to this reaction, the amount of film formation derived from decomposition products of the electrolyte due to cracking of particles increases, causing a capacity balance shift between the positive and negative electrodes . Further, it is known that SiO _x deteriorates with changes in particles when charge / discharge cycles are repeated. As described above, in the battery using SiO _x for the negative electrode, it is very difficult to detect the state of deterioration of the SiO _x negative electrode from the battery after the charge / discharge cycle because various factors are included in the battery capacity reduction. there were.

On the other hand, the present inventors have assiduously studied and experimented that, when the storage element 200 using silicon oxide (SiO _x ) as the negative electrode active material was discharged, the capacity with respect to voltage in a predetermined voltage range was reduced. It has been found that the capacitance change data indicating the amount of change changes characteristically. The inventors of the present application have found that the deterioration state of the storage element 200 can be accurately estimated by using the capacitance change data. Therefore, according to power storage element deterioration state estimation device 100, it is possible to improve the accuracy of estimating the deterioration state of power storage element 200 for power storage element 200 using silicon oxide as the negative electrode active material.

  In addition, as a result of intensive studies and experiments, the inventors of the present application have found that the capacity change data characteristically changes in a voltage range at the end of discharge where the potential of the negative electrode is equal to or higher than a predetermined potential. Therefore, according to power storage element deterioration state estimation device 100, the deterioration state of power storage element 200 can be accurately estimated by acquiring the capacitance change data in the voltage range.

In addition, as a result of intensive studies and experiments, the inventors of the present application have found that the capacity change data characteristically changes in the voltage range at the end of discharge where the potential of the negative electrode is 0.6 V (vs. Li ^/ Li ⁺ ) or higher. I found that. Therefore, according to power storage element deterioration state estimation device 100, the deterioration state of power storage element 200 can be accurately estimated by acquiring the capacitance change data in the voltage range.

  In addition, as a result of intensive studies and experiments, the present inventors have found that when the absolute value of the capacitance change data becomes smaller than a predetermined value, it can be determined that the storage element 200 has reached the end of its life. . Therefore, according to power storage element deterioration state estimating apparatus 100, the life of power storage element 200 can be estimated by making the determination.

  In addition, as a result of intensive studies and experiments, the present inventors have found that the deterioration state of the storage element 200 can be accurately estimated by using the relationship between the capacitance change data and the capacitance retention ratio. Therefore, according to power storage element deterioration state estimating apparatus 100, the estimation accuracy of the deterioration state of power storage element 200 can be improved.

  In addition, as a result of intensive studies and experiments, the inventors of the present application have found that when the value of the capacitance change data with respect to the capacitance retention ratio is out of a predetermined range, it can be determined that the storage element 200 has reached the end of its life. . Therefore, according to power storage element deterioration state estimating apparatus 100, the life of power storage element 200 can be estimated by making the determination.

  In addition, as a result of diligent studies and experiments, the inventors of the present application have found that the degradation state of the storage element 200 can be accurately estimated for the negative-electrode limited storage element 200. Therefore, according to power storage element deterioration state estimating apparatus 100, the estimation accuracy of the deterioration state of power storage element 200 can be improved.

  As described above, the storage element deterioration state estimation device 100 and the power storage system 10 according to the embodiment of the present invention have been described, but the present invention is not limited to this embodiment. In other words, the embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, in the above embodiment, the acquiring unit 110 acquires the capacity change data and the capacity maintenance rate by calculating the capacity change data and the capacity maintenance rate using the charge / discharge history of the power storage element 200. However, the acquisition unit 110 may calculate the capacity change data or the capacity maintenance rate using other information. Further, acquisition section 110 may acquire the capacity change data or the capacity maintenance rate from outside of power storage element deterioration state estimation apparatus 100.

  In the above-described embodiment, the storage element deterioration state estimation device 100 includes the storage unit 130. However, power storage element deterioration state estimation device 100 may not include storage unit 130, and may exchange information with an external memory.

  In the above-described embodiment, the storage unit 130 stores the charge / discharge history data 131 and the estimation data 132. However, any data may be stored in storage section 130 if storage element deterioration state estimating apparatus 100 is necessary for estimating the deterioration state of storage element 200.

  The processing unit included in the storage element deterioration state estimation device 100 according to the present invention is typically realized as an LSI (Large Scale Integration) which is an integrated circuit. That is, for example, as illustrated in FIG. 13, the present invention is realized as an integrated circuit 101 including the acquisition unit 110 and the estimation unit 120. FIG. 13 is a block diagram showing a configuration in which power storage element deterioration state estimation device 100 according to the embodiment of the present invention is implemented by an integrated circuit.

  Each processing unit included in the integrated circuit 101 may be individually integrated into one chip, or may be integrated into one chip so as to include a part or all of the processing units. Although an LSI is used here, it may be called an IC, a system LSI, a super LSI, or an ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. After the LSI is manufactured, a field programmable gate array (FPGA) that can be programmed or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  Furthermore, if an integrated circuit technology that replaces the LSI appears due to the progress of the semiconductor technology or another technology derived therefrom, the functional blocks may be naturally integrated using the technology. Adaptation of biotechnology is possible.

  The present invention can be realized not only as such a storage element deterioration state estimating apparatus 100 but also as a storage element deterioration state estimating method in which the characteristic processing performed by the storage element deterioration state estimating apparatus 100 is performed as a step. Can be realized.

  In addition, the present invention can be realized as a program for causing a computer (processor) to execute characteristic processing included in the method for estimating a deterioration state of a storage element, or a non-transitory computer-readable program (processor) storing the program. Recording media, for example, flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, BD (Blu-ray (registered trademark) Disc), semiconductor memory, flash memory, magnetic storage device, optical disk, It can also be realized as any medium such as a paper tape. Needless to say, such a program can be distributed via a recording medium such as a CD-ROM and a transmission medium such as the Internet.

  Further, a mode constructed by arbitrarily combining the components included in the above embodiments is also included in the scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention is applicable to a power storage element using silicon oxide as a negative electrode active material, and can be applied to a power storage element deterioration state estimation device and the like that can improve the accuracy of estimating the deterioration state of the power storage element.

REFERENCE SIGNS LIST 10 power storage system 100 power storage element deterioration state estimation device 101 integrated circuit 110 acquisition unit 120 estimation unit 130 storage unit 131 charge / discharge history data 132 estimation data 200 power storage element 300 housing case

Claims (12)

A storage element deterioration state estimating apparatus for estimating a deterioration state of a storage element having a positive electrode, a negative electrode, and a nonaqueous electrolyte,
For a power storage element having a negative electrode including a negative electrode active material containing silicon oxide (SiO _x ), in a predetermined voltage range when the power storage element is discharged, capacity change data indicating a change in capacity with respect to voltage is obtained. An acquisition unit to acquire,
Using the acquired capacitance change data, an estimating unit that estimates the deterioration state of the power storage element,
The acquisition unit is configured to set a voltage range at the end of discharge in which the potential of the negative electrode is equal to or higher than a predetermined potential, and a voltage range lower than a voltage value at which an absolute value of the capacity change data in a predetermined charge / discharge cycle is maximum. A storage element deterioration state estimating device that acquires the capacity change data in the voltage range of the predetermined charge / discharge cycle . The acquisition unit further acquires a capacity retention rate of the power storage element corresponding to the capacity change data,
The storage element deterioration state estimation device according to claim 1, wherein the estimation unit estimates the deterioration state of the storage element by using a relationship between the capacity change data and the capacity maintenance rate.   A storage element deterioration state estimating apparatus for estimating a deterioration state of a storage element having a positive electrode, a negative electrode, and a nonaqueous electrolyte,
  Silicon oxide (SiO _x A) for a power storage element having a negative electrode including a negative electrode active material containing the negative electrode active material, in a predetermined voltage range when the power storage element is discharged, an acquisition unit that acquires capacitance change data indicating a change in capacitance with respect to voltage;
  Using the acquired capacitance change data, an estimating unit that estimates the deterioration state of the power storage element,
  The acquiring unit is a voltage range at the end of discharge in which the potential of the negative electrode is equal to or higher than a predetermined potential, and sets the voltage range lower than the voltage value at which the absolute value of the capacitance change data is the maximum as the predetermined voltage range. Acquiring the capacitance change data in a voltage range,
  The acquisition unit further acquires a capacity retention rate of the power storage element corresponding to the capacity change data,
  The estimation unit estimates a deterioration state of the power storage element using a relationship between the capacity change data and the capacity maintenance rate.
  A storage element deterioration state estimation device. The storage element deterioration state estimating device according to claim 2 or 3, wherein the estimation unit determines that the storage element has reached the end of its life when the value of the capacity change data with respect to the capacity maintenance ratio is out of a predetermined range. . The said acquisition part makes the voltage range in the last stage of discharge in which the electric potential of the said negative electrode is 0.6V (vs. Li ^/ Li ^<+> ) or more the said predetermined voltage range, and acquires the said capacitance change data in the said voltage range. The storage element deterioration state estimating device according to any one of claims 1 to 4 . The storage element deterioration state estimation device according to any one of claims 1 to 5 , wherein the obtaining unit obtains the capacitance change data for the negative-electrode limited storage element whose capacity is limited by a negative electrode. A power storage element including a positive electrode, a negative electrode including a negative electrode active material containing silicon oxide (SiO _x ), and a nonaqueous electrolyte;
A power storage system comprising: the power storage element deterioration state estimating device according to any one of claims 1 to 6 , which estimates a deterioration state of the power storage element. A computer is a power storage element deterioration state estimation method for estimating a deterioration state of a power storage element having a positive electrode, a negative electrode, and a nonaqueous electrolyte,
For a power storage element having a negative electrode including a negative electrode active material containing silicon oxide (SiO _x ), in a predetermined voltage range when the power storage element is discharged, capacity change data indicating a change in capacity with respect to voltage is obtained. An acquiring step for acquiring;
Using the obtained capacitance change data, an estimation step of estimating the deterioration state of the power storage element,
In the acquiring step, the voltage range at the end of discharge in which the potential of the negative electrode is equal to or higher than a predetermined potential, and the voltage range lower than the voltage value at which the absolute value of the capacity change data in a predetermined charge / discharge cycle is the maximum is set to the predetermined range. And obtaining the capacity change data in the voltage range of the predetermined charge / discharge cycle .   A computer is a power storage element deterioration state estimation method for estimating a deterioration state of a power storage element having a positive electrode, a negative electrode, and a nonaqueous electrolyte,
  Silicon oxide (SiO _x A) for a power storage element having a negative electrode including a negative electrode active material containing a negative electrode active material, in a predetermined voltage range when the power storage element is discharged, an acquisition step of acquiring capacitance change data indicating a change in capacitance with respect to voltage;
  Using the obtained capacitance change data, an estimating step of estimating the deterioration state of the power storage element,
  In the obtaining step, the potential of the negative electrode is a voltage range at the end of discharge at or above a predetermined potential, and a voltage range lower than a voltage value at which the absolute value of the capacitance change data is the maximum is defined as the predetermined voltage range. Acquiring the capacitance change data in a voltage range,
  In the obtaining step, further obtains a capacity retention rate of the power storage element corresponding to the capacity change data,
  In the estimating step, a deterioration state of the power storage element is estimated using a relationship between the capacity change data and the capacity maintenance rate.
  Energy storage element deterioration state estimation method. A program for causing a computer to execute steps included in the method for estimating a state of deterioration of a storage element according to claim 8 . An integrated circuit for estimating the deterioration state of a storage element having a positive electrode, a negative electrode, and a nonaqueous electrolyte,
For a power storage element having a negative electrode including a negative electrode active material containing silicon oxide (SiO _x ), in a predetermined voltage range when the power storage element is discharged, capacity change data indicating a change in capacity with respect to voltage is obtained. An acquisition unit to acquire,
Using the acquired capacitance change data, an estimating unit that estimates the deterioration state of the power storage element,
The acquisition unit is configured to set a voltage range at the end of discharge in which the potential of the negative electrode is equal to or higher than a predetermined potential, and a voltage range lower than a voltage value at which an absolute value of the capacity change data in a predetermined charge / discharge cycle is maximum. And acquiring the capacitance change data in the voltage range of the predetermined charge / discharge cycle .   An integrated circuit for estimating a deterioration state of a storage element having a positive electrode, a negative electrode, and a nonaqueous electrolyte,
  Silicon oxide (SiO _x A) for a power storage element having a negative electrode including a negative electrode active material containing the negative electrode active material, in a predetermined voltage range when the power storage element is discharged, an acquisition unit that acquires capacitance change data indicating a change in capacitance with respect to voltage;
  Using the acquired capacitance change data, an estimating unit that estimates the deterioration state of the power storage element,
  The acquiring unit is a voltage range at the end of discharge in which the potential of the negative electrode is equal to or higher than a predetermined potential, and sets the voltage range lower than the voltage value at which the absolute value of the capacitance change data is the maximum as the predetermined voltage range. Acquiring the capacitance change data in a voltage range,
  The acquisition unit further acquires a capacity retention rate of the power storage element corresponding to the capacity change data,
  The estimation unit estimates a deterioration state of the power storage element using a relationship between the capacity change data and the capacity maintenance rate.
  Integrated circuit.

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