JP2019032274A - Battery state estimation device and power supply device - Google Patents

Abstract

A battery state estimation device capable of estimating the state of charge of a lithium ion secondary battery with high accuracy. In a battery state estimation device 1, a shape change information extraction unit 32 extracts a shape change information from a shape change information storage unit 31 based on positive electrode information of a lithium ion secondary battery 60 and specific information of the lithium ion secondary battery 60. The shape change information of the positive electrode OCV curve is extracted, and the positive electrode OCV curve specifying unit 33 specifies the positive electrode OCV curve based on the shape change information of the positive electrode OCV curve. Then, the battery OCV curve calculation unit 50 calculates a battery OCV curve indicating the relationship between the charged state and the open circuit voltage in the lithium ion secondary battery 60 from the identified positive electrode OCV curve and negative electrode OCV curve, and estimates the charged state. The charging state in the lithium ion secondary battery 60 is estimated by the unit 51 from the open circuit voltage of the lithium ion secondary battery 60 and the calculated battery OCV curve. [Selection] Figure 1

Description

  The present invention relates to a battery state estimation device and a power supply device.

  In the secondary battery, the chargeable / dischargeable battery capacity depends on the electrode capacity of the positive electrode and the negative electrode. And when both electrodes deteriorate, the electrode capacity in a positive electrode and a negative electrode will fall, and the battery capacity which can be charged / discharged will fall. As an apparatus for estimating the state of charge due to the deterioration of the secondary battery, Patent Document 1 previously acquires an OCV curve indicating the relationship between the electrode capacity and the open circuit voltage for each electrode, and each electrode has deteriorated. In some cases, the state of charge of the secondary battery is reflected by reflecting the deterioration of the electrode as if the OCV curve changes for each electrode so as to decrease while maintaining the overall shape, that is, changes similar to the OCV curve. The structure which estimates this is disclosed.

JP 2010-60384 A

  However, the shape change of the OCV curve of the electrode due to deterioration in the secondary battery does not necessarily change in a similar manner. Therefore, in the configuration disclosed in the cited document 1, if the shape change of the OCV curve does not change similarly, the estimation accuracy of the charged state of the secondary battery is lowered, so there is room for improvement in improving the estimation accuracy. .

  The present invention has been made in view of such a background, and an object of the present invention is to provide a battery state estimation device capable of estimating the state of charge of a lithium ion secondary battery with high accuracy.

One aspect of the present invention is a battery state estimation device (1) for estimating the state of charge of a lithium ion secondary battery (60),
A specific information acquisition unit (10) for acquiring specific information related to the lithium ion secondary battery;
A battery OCV acquisition unit (20) for acquiring an open-circuit voltage of the lithium ion secondary battery;
A positive electrode information acquisition unit (30) for acquiring positive electrode information including an active material amount and a capacity density in the positive electrode of the lithium ion secondary battery;
A negative electrode information acquisition unit (40) for acquiring negative electrode information including an active material amount and a capacity density in the negative electrode of the lithium ion secondary battery;
A shape change information storage unit (31) in which shape change information of a positive OCV curve indicating a relationship between an electrode capacity and an electrode open-circuit voltage in the positive electrode is stored in a state associated with the positive electrode information and the specific information; ,
Shape change for extracting shape change information of the positive electrode OCV curve from the shape change information storage unit based on the positive electrode information acquired by the positive electrode information acquisition unit and the specific information acquired by the specific information acquisition unit An information extraction unit (32);
A positive OCV curve specifying unit (33) for specifying the positive OCV curve based on the shape change information of the positive OCV curve acquired by the shape change information extracting unit;
Based on the negative electrode information acquired by the negative electrode information acquisition unit, a negative electrode OCV curve specifying unit (41) for specifying a negative electrode OCV curve indicating a relationship between an electrode capacity and an electrode open voltage in the negative electrode,
The relationship between the state of charge and the open-circuit voltage in the lithium ion secondary battery is shown from the positive electrode OCV curve specified by the positive electrode OCV curve specifying unit and the negative electrode OCV curve specified by the negative electrode OCV curve specifying unit. A battery OCV curve calculation unit (50) for calculating a battery OCV curve;
Charging that estimates the state of charge in the lithium ion secondary battery from the open circuit voltage of the lithium ion secondary battery acquired by the battery OCV acquisition unit and the battery OCV curve calculated by the battery OCV curve calculation unit A state estimation unit (51);
Is in a battery state estimation device.

  As a result of intensive studies, the inventors have noticeably changed the shape of the OCV curve of the electrode due to deterioration in the secondary battery, particularly in the positive electrode, and the shape change of the OCV curve in the positive electrode strongly affects the estimation accuracy of the state of charge. I found out. And in the said battery state estimation apparatus, the shape change information of the positive electrode OCV curve is memorize | stored in the shape change information storage part. Further, the shape change information extraction unit extracts the shape change information of the positive electrode OCV curve from the shape change information storage unit based on the positive electrode information including the active material amount and capacity density in the positive electrode and the specific information on the lithium ion secondary battery. Then, the positive electrode OCV curve is specified by the positive electrode OCV curve specifying unit. The charge state estimation unit estimates the charge state from the battery OCV curve calculated from the positive electrode OCV curve and the negative electrode OCV curve and the open voltage of the lithium ion secondary battery. As described above, since the battery OCV curve reflects the shape change information of the positive electrode OCV curve, the state of charge can be estimated with high accuracy.

  As described above, according to the present invention, it is possible to provide a battery state estimation device that can estimate the state of charge of a lithium ion secondary battery with high accuracy.

  In addition, the code | symbol in the parenthesis described in the means to solve a claim and a subject shows the correspondence with the specific means as described in embodiment mentioned later, and limits the technical scope of this invention. It is not a thing.

The block diagram showing the structure of the battery state estimation apparatus and power supply device in Embodiment 1. FIG. The conceptual diagram for demonstrating the shape change of the positive electrode OCV curve in Embodiment 1. FIG. FIG. 3 is a flowchart showing a usage mode in the first embodiment. 4A is a diagram showing the results of the confirmation test in Test Example 1, and FIG. 4B is a diagram showing the results of the confirmation test in Test Example 2. FIG. 5A is a diagram showing the results of the confirmation test in Test Example 3, and FIG. 5B is a diagram showing the results of the confirmation test in Test Example 2. FIG. The figure which shows the result of the confirmation test in Embodiment 4.

(Embodiment 1)
Embodiments of the battery state estimation device and the power supply device will be described with reference to FIGS.
The battery state estimation device 1 of the present embodiment shown in FIG. 1 is for estimating the state of charge of a lithium ion secondary battery 60. The battery state estimation device 1 includes a specific information acquisition unit 10, a battery OCV acquisition unit 20, a positive electrode information acquisition unit 30, a negative electrode information acquisition unit 40, a shape change information storage unit 31, a shape change information extraction unit 32, and a positive electrode OCV curve specification unit. 33, a negative electrode OCV curve specifying unit 41, a battery OCV curve calculating unit 50, and a charged state estimating unit 51.

The specific information acquisition unit 10 acquires specific information regarding the lithium ion secondary battery 60.
The open voltage of the battery OCV acquisition unit 20 and the lithium ion secondary battery 60 is acquired.
The positive electrode information acquisition unit 30 acquires positive electrode information including the amount of active material and capacity density in the positive electrode of the lithium ion secondary battery 60.
The negative electrode information acquisition unit 40 acquires negative electrode information including the amount of active material and capacity density in the negative electrode of the lithium ion secondary battery 60.
The shape change information storage unit 31 stores shape change information of the positive electrode OCV curve indicating the relationship between the electrode capacity and the electrode open voltage in the positive electrode in a state associated with the positive electrode information and the specific information.

Based on the positive electrode information acquired by the positive electrode information acquisition unit 30 and the specific information acquired by the specific information acquisition unit 10, the shape change information extraction unit 32 acquires the shape change information of the positive OCV curve from the shape change information storage unit 31. To extract.
The positive electrode OCV curve specifying unit 33 specifies the positive electrode OCV curve based on the shape change information of the positive electrode OCV curve acquired by the shape change information extracting unit 32.
The negative electrode OCV curve specifying unit 41 specifies a negative electrode OCV curve indicating the relationship between the electrode capacity and the electrode open circuit voltage in the negative electrode based on the negative electrode information acquired by the negative electrode information acquiring unit 40.
The battery OCV curve calculation unit 50 calculates the charge state and the open circuit voltage in the lithium ion secondary battery 60 from the positive electrode OCV curve specified by the positive electrode OCV curve specification unit and the negative electrode OCV curve specified by the negative electrode OCV curve specification unit 41. A battery OCV curve showing the relationship is calculated.
The charge state estimation unit 51 uses the open voltage of the lithium ion secondary battery 60 acquired by the battery OCV acquisition unit 20 and the battery OCV curve calculated by the battery OCV curve calculation unit 50 to determine whether the lithium ion secondary battery 60 Estimate the state of charge.

Hereinafter, the battery state estimation device 1 and the power supply device 100 of the present embodiment will be described in detail.
A power supply device 100 shown in FIG. 1 includes a battery state estimation device 1 and a lithium ion secondary battery 60 (hereinafter also referred to as a secondary battery 60). The power supply apparatus 100 can be used as a power supply apparatus for an electric vehicle, for example. The secondary battery 60 includes a positive electrode and a negative electrode. Although the positive electrode material in the secondary battery 60 is not particularly limited, for example, lithium manganate LiMn ₂ O ₄ and nickel-manganese-lithium cobaltate LiNiMnCoO ₂ can be used. Anode material in secondary battery 60 is not particularly limited, for example, may be graphite, lithium titanate Li ₄ Ti ₅ O _12.

  The specific information acquisition unit 10 illustrated in FIG. 1 includes a predetermined sensor that can detect specific information to be acquired, or an arithmetic device that derives specific information based on a value detected by the predetermined sensor. The specific information acquired by the specific information acquisition unit 10 may be at least one of a usage history and battery characteristics of the secondary battery 60. As the usage history of the secondary battery 60, history information regarding at least one of a charging state, a current value, a voltage value, and a battery temperature can be employed. Further, the battery characteristics of the secondary battery 60 can be at least one of a battery resistance, a section battery capacity, and a ratio between an output resistance and an input resistance. For example, when the charging state and the battery characteristics are acquired as the specific information of the secondary battery 60, the correspondence relationship between the specific information and a predetermined parameter that can be detected from the secondary battery 60 is stored in advance. And specific information is computable from the predetermined | prescribed parameter detected from the secondary battery 60 when acquiring specific information, and the said corresponding relationship. The correspondence can be in the form of a theoretical model, a mathematical formula, a map, or the like. The specific information acquired by the specific information acquisition unit 10 is stored in a specific information storage unit including a rewritable memory (not shown).

  The battery OCV acquisition unit 20 illustrated in FIG. 1 includes a voltage sensor for acquiring the open circuit voltage of the secondary battery 60. Acquisition of the open circuit voltage of the secondary battery 60 by the battery OCV acquisition unit 20 may be performed constantly, or may be performed according to the timing at which the state of charge is estimated. Note that the open circuit voltage of the secondary battery 60 acquired by the battery OCV acquisition unit 20 is stored in a battery OCV storage unit including a rewritable memory (not shown).

  The positive electrode information acquisition unit 30 illustrated in FIG. 1 includes a device that can acquire positive electrode information to be acquired. The positive electrode information includes the active material amount and capacity density of the positive electrode of the secondary battery 60. The positive electrode information acquisition unit 30 stores a correspondence relationship between the active material amount and capacity density of the positive electrode, the open-circuit voltage of the secondary battery 60, the battery current, and the battery temperature, which are acquired in advance from the model secondary battery. Then, the positive electrode information acquisition unit 30 acquires the open circuit voltage, battery current, and battery temperature of the secondary battery 60, and calculates and acquires the active material amount and capacity density of the positive electrode based on the correspondence relationship. Note that the amount of active material of the positive electrode indicates the lithium receiving ability in the positive electrode. The capacity density indicates the concentration of lithium ions in the electrolytic solution.

  The shape change information storage unit 31 shown in FIG. 1 includes a non-rewritable memory, and stores shape change information of the positive OCV curve in advance. The positive electrode OCV curve indicates the correspondence between the capacity at the positive electrode and the electrode open-circuit voltage, and as shown in FIG. 2, is represented by a curve in a two-dimensional graph of the capacity at the positive electrode and the electrode open-circuit voltage. The shape change information of the positive electrode OCV curve is information indicating how the shape of the positive electrode OCV curve changes due to deterioration of the positive electrode. With this shape change information, as shown in FIG. 2, the shape of the positive electrode OCV curve after deterioration can be calculated from the positive electrode OCV curve before deterioration. The shape change information can be a map created from the shapes of a number of positive electrode OCV curves obtained by an acceleration test of the model positive electrode, or a function represented by an approximate expression.

  The shape change information extraction unit 32 shown in FIG. The shape change information extracted by the shape change information extraction unit 32 can be stored in a shape change information storage unit (not shown). Moreover, the positive electrode OCV curve specific | specification part 33 also consists of arithmetic units. The positive OCV curve specified by the positive OCV curve specifying unit 33 can be stored in a positive OCV curve storage unit (not shown).

  The negative electrode information acquisition unit 40 illustrated in FIG. 1 includes a device that can acquire negative electrode information to be acquired. The negative electrode information includes the active material amount and capacity density of the negative electrode of the secondary battery 60. The negative electrode information acquisition unit 40 has the same configuration as the positive electrode information acquisition unit 30 described above. Moreover, the negative electrode OCV curve specific | specification part 41 consists of arithmetic units. As shown in FIG. 2, the negative electrode OCV curve specifying unit 41 specifies the deteriorated negative electrode OCV curve. The negative OCV curve specified by the negative electrode OCV curve specifying unit 41 can be stored in a negative electrode OCV curve storage unit (not shown).

  The battery OCV curve calculation unit 50 shown in FIG. 1 is composed of an arithmetic unit, and the battery OCV curve is calculated from the difference between the positive OCV curve specified by the positive electrode OCV curve specifying unit 33 and the negative electrode OCV curve specified by the negative electrode OCV curve specifying unit 41. Is calculated. The battery OCV curve calculated by the battery OCV curve calculation unit 50 can be stored in a battery OCV curve storage unit (not shown).

  The charging state estimation unit 51 illustrated in FIG. 1 includes an arithmetic device, and estimates the charging state from the battery OCV curve and the OCV of the secondary battery 60. Although not shown, the battery state estimation device 1 may include an estimation result display unit that displays an estimation result obtained by the charge state estimation unit 51.

  Next, the usage mode of the battery state estimation apparatus 1 will be described with reference to the flowchart shown in FIG. First, as shown in FIG. 3, in step S <b> 1, the specific information acquisition unit 10 acquires specific information of the secondary battery 60. In the present embodiment, an SOC (State Of Charge) charge history that is history information of the secondary battery 60 is acquired as the specific information.

  Then, it progresses to step S2 shown in FIG. 3, and the positive electrode information acquisition part 30 acquires the active material amount and capacity density of the positive electrode as positive electrode information. Also, the negative electrode information acquisition unit 40 acquires the active material amount and capacity density of the negative electrode as negative electrode information.

  And in step S3 shown in FIG. 3, in the shape change information extraction part 32, based on the positive electrode information acquired in the positive electrode information acquisition part 30, and the specific information acquired in the specific information acquisition part 10, a shape change information storage part The shape change information is extracted from 31.

  Then, in step S4 shown in FIG. 3, the positive electrode OCV curve specifying unit 33 specifies the positive electrode OCV curve based on the shape change information of the positive electrode OCV curve acquired by the shape change information extracting unit 32. Further, the negative electrode OCV curve specifying unit 41 specifies a negative electrode OCV curve indicating the relationship between the electrode capacity and the electrode open voltage in the negative electrode based on the negative electrode information acquired by the negative electrode information acquiring unit 40.

  3, the battery OCV curve calculation unit 50 calculates a battery OCV curve from the positive electrode OCV curve and the negative electrode OCV curve. Furthermore, in step S <b> 6, the battery OCV acquisition unit 20 acquires the open circuit voltage of the secondary battery 60. Thereafter, the process proceeds to step S7, and the secondary state is calculated from the open circuit voltage of the secondary battery 60 acquired by the battery OCV acquisition unit 20 and the battery OCV curve calculated by the battery OCV curve calculation unit 50 by the charge state estimation unit 51. The state of charge in the battery 60 is estimated.

Next, the confirmation test about the estimation precision of SOC by the battery state estimation apparatus 1 of this embodiment was performed. The positive electrode material of the secondary battery 60 was LMO (lithium manganate), the negative electrode material was LTO (lithium titanate), and the electrolyte was 1M LiPF ₆ EC: DEC = 1: 1. In this confirmation test, the SOC history is used as the specific information of the secondary battery 60. In Test Example 1, the SOC in the initial state and the first deterioration state was estimated. The first deterioration state is a state where the first SOC history is stored until the SOC is 30%, the storage temperature is 75 ° C., and the capacity deterioration rate is 15%. In Test Example 2, the SOC in the initial state and the second deterioration state was estimated. The second deterioration state was a state where the second SOC history was stored until the SOC was 90%, the storage temperature was 75 ° C., and the capacity deterioration rate was 15%. The capacity deterioration rate indicates the ratio of the full charge capacity in the deterioration state to the full charge capacity in the initial state. And according to the flowchart shown in FIG. 3, SOC when the open circuit voltage of the secondary battery 60 is 2.5V was estimated, and the estimation result was shown to FIG. 4 (a) and FIG.4 (b). In FIG. 4A and FIG. 4B, the SOC at the time of full charge in the initial state and the SOC at the time of full charge in each deterioration state are represented as 100%.

  As shown in FIG. 4A, in Test Example 1, in the initial state, the estimated SOC value when the open-circuit voltage of the secondary battery 60 is 2.5 V is 62%, and the estimated value in the first deterioration state is obtained. The value was 50%. Moreover, as shown in FIG.4 (b), in the test example 2, the estimated value of SOC in an initial state and a 2nd degradation state was 62%. In Test Example 2, there was no difference in estimated values between the initial state and the second deterioration state, but in Test Example 1, a difference of 12% occurred between the initial state and the first deterioration state. And if the shape change of the positive electrode OCV curve is not taken into consideration based on the SOC history as in the prior art, the estimated value in the first deterioration state is the same as that in the initial state and includes an error of 12%. Therefore, in the battery state estimation apparatus 1 of Embodiment 1, it was confirmed that the estimation accuracy of the SOC is improved as compared with the conventional case by considering the shape change of the positive electrode OCV curve due to the difference in the SOC history.

Next, the effect in the battery state estimation apparatus 1 of this embodiment is explained in full detail.
In the battery state estimation device 1 of this embodiment, the shape change information of the positive electrode OCV curve is stored in the shape change information storage unit 31. Then, the shape change information extraction unit 32 changes the shape of the positive OCV curve from the shape change information storage unit 31 based on the positive electrode information including the active material amount and the capacity density in the positive electrode and the specific information on the lithium ion secondary battery 60. Information is extracted, and the positive electrode OCV curve specifying unit 33 specifies the positive electrode OCV curve. Then, the battery OCV curve calculation unit 50 calculates a battery OCV curve from the positive electrode OCV curve and the negative electrode OCV curve. Thereafter, the charge state estimation unit 51 estimates the charge state from the battery OCV curve and the open voltage of the lithium ion secondary battery 60. As described above, since the battery OCV curve reflects the shape change information of the positive electrode OCV curve, the state of charge can be estimated with high accuracy.

  In the battery state estimation device 1 of the present embodiment, the specific information regarding the lithium ion secondary battery 60 is the usage history of the lithium ion secondary battery 60. Thereby, since the usage history of the lithium ion secondary battery 60 can be reflected in the shape change information of the positive electrode OCV curve, the state of charge of the lithium ion secondary battery 60 can be estimated with higher accuracy.

  Furthermore, the use history can be history information regarding at least one of the charge state, battery temperature, current value, and voltage value. In the battery state estimation device 1 of the present embodiment, the charge state is adopted as the use history. ing. Since the history information on the state of charge, battery temperature, current value, and voltage value is an element that affects the deterioration of the positive electrode, when at least one of these is used as the use history, charging of the lithium ion secondary battery 60 is performed. The state can be estimated with higher accuracy. Note that any combination can be selected from the charge state, battery temperature, current value, and voltage value as the usage history.

  In addition, the power supply device 100 according to the present embodiment includes a battery state estimation device 1 and a lithium ion secondary battery 60 whose charge state is estimated by the battery state estimation device 1, and uses a positive electrode material of the lithium ion secondary battery 60. , Lithium manganate or nickel-manganese-cobalt acid lithium. In such a positive electrode material, since the shape change of the positive electrode OCV curve due to deterioration is significant, the battery state estimation device 1 can estimate the state of charge with higher accuracy than before.

  In this embodiment, graphite or LTO is adopted as the negative electrode material. Therefore, since the shape change of the negative electrode OCV curve accompanying the deterioration is very small, it is not necessary to consider the shape change of the negative electrode OCV curve accompanying the deterioration. Therefore, in the present embodiment, the negative electrode OCV curve specifying unit 41 specifies the negative electrode OCV curve based on the negative electrode information acquired by the negative electrode information acquiring unit 40. In addition, when other materials are adopted as the negative electrode material, the negative electrode is configured so as to positively consider the change in the shape of the negative electrode OCV curve as necessary in the same manner as the positive electrode in the present embodiment. May be.

(Embodiment 2)
In the first embodiment, the SOC history is used as the usage history that is the specific information of the secondary battery 60. However, in the second embodiment, the temperature history is used as the usage history instead. In addition, the other structure in Embodiment 2 is the same as that of Embodiment 1, and there exists an effect equivalent to Embodiment 1 also in Embodiment 2. FIG.

And the confirmation test was done about the estimation precision of SOC by the battery state estimation apparatus 1 in Embodiment 2. FIG. The positive electrode material of the secondary battery 60 was NMC (nickel-manganese-lithium cobaltate), the negative electrode material was Li (lithium), and the electrolyte was 1M LiPF ₆ EC: DEC = 1: 1. In this confirmation test, the temperature history is used as the specific information of the secondary battery 60. In Test Example 3, the SOC in the initial state and the third deterioration state was estimated. In the third deterioration state, as the first temperature history, the temperature was 55 ° C., the charge / discharge rate was 1 C, and the capacity deterioration rate was 22%. In Test Example 4, the SOC in the initial state and the fourth deterioration state was estimated. The fourth deterioration state was a state where the second temperature history was used until the capacity deterioration rate reached 22% in a state where the temperature was 25 ° C. and the charge / discharge rate was 1 C. Then, according to the flow shown in FIG. 3, the SOC when the open-circuit voltage of the secondary battery 60 is 3.9 V is estimated, and the estimation results are shown in FIGS. 5 (a) and 5 (b).

  As shown in FIG. 5A, in Test Example 3, in the initial state, the estimated SOC value when the open-circuit voltage of the secondary battery 60 is 3.9 V is 61%, and the estimated value in the third deterioration state is obtained. The value was 41%, and there was a difference of 20% in the estimated value. Further, as shown in FIG. 5B, in Test Example 4, in the initial state, the estimated value of SOC when the open-circuit voltage of the secondary battery 60 is 3.9 V is 41%, and in the fourth deterioration state, The estimated value was 48%, and the estimated value was 7% different. Therefore, in the present embodiment, as in the case of the first embodiment, it has been confirmed that the estimation accuracy of the SOC is improved as compared with the conventional case by considering the change in the shape of the positive electrode OCV curve due to the difference in the temperature history.

(Embodiment 3)
In the first and second embodiments, the use history is used as the specific information of the secondary battery 60, but in the third embodiment, battery characteristics are used as the specific information of the secondary battery 60 instead. Other configurations in the third embodiment are the same as those in the first embodiment. In the third embodiment, the same effects as those in the first embodiment are obtained.

  Since the battery characteristics of the secondary battery 60 are factors that affect the deterioration of the positive electrode, the state of charge of the secondary battery 60 can be estimated with high accuracy by using the battery characteristics as the specific information. In addition, at least one of the battery resistance, the section capacity, and the ratio between the output resistance and the input resistance can be adopted as the battery characteristics that are specific information of the secondary battery 60. And the said battery characteristic can be selected by arbitrary combinations from battery resistance, section capacity, and the ratio of output resistance and input resistance.

  In the third embodiment, the section capacity is used as the battery characteristic of the secondary battery 60. The section capacity refers to the battery capacity of the secondary battery 60 in a predetermined range. The range of the section capacity is preferably a range in which the change in the OCV curve is large. By using this range as the specific information of the secondary battery 60, the shape change of the OCV curve is predicted with high accuracy by acquiring the section capacity based on the correspondence between the section capacity and the shape change of the OCV curve. be able to.

  For example, a capacity with an open circuit voltage of the secondary battery 60 in the confirmation test in the second embodiment of 3.7 to 3.8 V can be adopted as the section capacity. As shown in FIG. 5A and FIG. 5B, in such a range, the change in the capacity before and after deterioration is large. In addition, the SOC can be estimated with high accuracy. Therefore, the third embodiment also has the same effect as the first embodiment.

(Embodiment 4)
In the third embodiment, the section capacity is used as the battery characteristic of the secondary battery 60, but in the fourth embodiment, the battery resistance of the secondary battery 60 is used instead. Since there is a correlation between the battery resistance change and the shape change of the OCV curve, the shape of the OCV curve is obtained by obtaining the battery resistance based on the correspondence between the battery resistance and the shape change of the OCV curve. Changes can be predicted with high accuracy. In particular, in the deterioration with a large change in the shape of the OCV curve, the low-frequency resistance component increases specifically. Therefore, the shape change of the OCV curve can be predicted with higher accuracy by acquiring the low frequency resistance component based on the correspondence relationship between the low frequency resistance component and the shape change of the OCV curve. As said low frequency, it can be 10 Hz or less, for example.

  In the battery state estimation device 1 of the present embodiment, Cole-Cole plot diagrams in the third deterioration state and the fourth deterioration state were created based on the impedance method under the same test conditions as the test in the second embodiment. As shown in FIG. 6, the 10 Hz resistance component increases specifically. Therefore, the SOC of the secondary battery 60 can be estimated with high accuracy by predicting the shape change of the OCV curve from the correspondence between the resistance component of 10 Hz in the battery resistance of the secondary battery 60 and the shape change of the OCV curve. . Therefore, the fourth embodiment has the same effects as the first embodiment.

  The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Battery state estimation apparatus 10 Specific information acquisition part 20 Battery OCV acquisition part 30 Positive electrode information acquisition part 40 Negative electrode information acquisition part 31 Shape change information storage part 32 Shape change information extraction part 33 Positive electrode OCV curve specific part 41 Negative electrode OCV curve specific part 50 Battery OCV curve calculation unit 51 Charge state estimation unit 100 Power supply device

Claims (5)

A battery state estimation device (1) for estimating a state of charge of a lithium ion secondary battery (60), comprising:
A specific information acquisition unit (10) for acquiring specific information related to the lithium ion secondary battery;
A battery OCV acquisition unit (20) for acquiring an open-circuit voltage of the lithium ion secondary battery;
A positive electrode information acquisition unit (30) for acquiring positive electrode information including an active material amount and a capacity density in the positive electrode of the lithium ion secondary battery;
A negative electrode information acquisition unit (40) for acquiring negative electrode information including an active material amount and a capacity density in the negative electrode of the lithium ion secondary battery;
A shape change information storage unit (31) in which shape change information of a positive OCV curve indicating a relationship between an electrode capacity and an electrode open-circuit voltage in the positive electrode is stored in a state associated with the positive electrode information and the specific information; ,
Shape change for extracting shape change information of the positive electrode OCV curve from the shape change information storage unit based on the positive electrode information acquired by the positive electrode information acquisition unit and the specific information acquired by the specific information acquisition unit An information extraction unit (32);
A positive OCV curve specifying unit (33) for specifying the positive OCV curve based on the shape change information of the positive OCV curve acquired by the shape change information extracting unit;
Based on the negative electrode information acquired by the negative electrode information acquisition unit, a negative electrode OCV curve specifying unit (41) for specifying a negative electrode OCV curve indicating a relationship between an electrode capacity and an electrode open voltage in the negative electrode,
The relationship between the state of charge and the open-circuit voltage in the lithium ion secondary battery is shown from the positive electrode OCV curve specified by the positive electrode OCV curve specifying unit and the negative electrode OCV curve specified by the negative electrode OCV curve specifying unit. A battery OCV curve calculation unit (50) for calculating a battery OCV curve;
Charging that estimates the state of charge in the lithium ion secondary battery from the open circuit voltage of the lithium ion secondary battery acquired by the battery OCV acquisition unit and the battery OCV curve calculated by the battery OCV curve calculation unit A state estimation unit (51);
A battery state estimating device.   The battery state estimation apparatus according to claim 1, wherein the specific information related to the lithium ion secondary battery is at least one of a usage history and battery characteristics of the lithium ion secondary battery.   The battery state estimation device according to claim 2, wherein the usage history is history information regarding at least one of a charging state, a battery temperature, a current value, and a voltage value.   The battery state estimation device according to claim 2 or 3, wherein the battery characteristic is at least one of a battery resistance, a section battery capacity, and a ratio between an output resistance and an input resistance. A power supply device (100) comprising: the battery state estimation device according to any one of claims 1 to 4; and a lithium ion secondary battery whose charge state is estimated by the battery state estimation device,
The power supply device in which the positive electrode material of the lithium ion secondary battery is lithium manganate or nickel-manganese-cobaltate.

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