WO2019194205A1

WO2019194205A1 - Secondary battery diagnosing device and diagnosing method

Info

Publication number: WO2019194205A1
Application number: PCT/JP2019/014718
Authority: WO
Inventors: 成岡　慶紀
Original assignee: 株式会社スリーダム
Priority date: 2018-04-06
Filing date: 2019-04-03
Publication date: 2019-10-10
Also published as: JP7063455B2; TW202004210A; JP2019185969A

Abstract

The objective of the present invention is to determine a point in time at which a pole has migrated from one pole toward another pole, which is the main cause of a reduction in the reversible capacity of a rechargeable battery. The point in time at which a pole has migrated from one pole toward another pole, which is the main cause of a reduction in the reversible capacity of a rechargeable battery, is determined on the basis of an open circuit voltage (OCV) characteristic of the battery during a prescribed charging and discharging idle period after a discharging period in a battery charging and discharging cycle.

Description

Secondary battery diagnostic device and diagnostic method

The present invention relates to a rechargeable secondary battery, and more particularly, diagnosing the state of the secondary battery, and predicting the lifetime of the secondary battery based on the diagnosis, and the secondary battery Is related to keeping in good condition.

Rechargeable secondary batteries (hereinafter simply referred to as secondary batteries) are widely used as consumer power sources. Secondary batteries used in recent electric vehicles and road leveling are required to be usable for a long period of time, that is, to have a long life. In addition, when a secondary battery is used over a long period of time, it is extremely important to predict its life.

In a secondary battery, it is known that the pole (positive electrode, negative electrode) deteriorates as the cumulative use period (or cumulative number of charge / discharge cycles) increases, and the reversible capacity decreases as the pole deteriorates.

Note that the reversible capacity is a capacity that can be charged and discharged between a predetermined end-of-charge voltage and end-of-discharge voltage, that is, a capacity that can be actually used out of the capacity of the secondary battery. In addition, there is an irreversible capacity associated with a reversible capacity, which is a capacity of the secondary battery that cannot be output.

Japanese Patent Laid-Open No. 2003-178812 (Patent Document 1) discloses an invention related to a technique for evaluating a lithium secondary battery. In the invention described in Patent Document 1, a technique of “evaluating the life characteristics of a lithium secondary battery by calculating the capacity (Qt) of the lithium secondary battery after a predetermined time according to a predetermined formula” is used. Briefly, in the invention described in Patent Document 1, the lithium secondary battery can be recharged in proportion to the cumulative use period from the beginning of the life of the lithium secondary battery (at the start of use of the lithium secondary battery). Assuming that the capacity (reversible capacity) will decrease, predict the decrease in reversible capacity of lithium secondary batteries using the linear proportional relationship between the cumulative use period from the beginning of the life and the reversible capacity is doing.

There is also a technology for predicting the decrease in reversible capacity of lithium-ion batteries on pages 21 to 26 of Volume 5 Issue 1 (issued June 27, 2008) (Non-Patent Document 1) of "GS Yuasa Technical Report". It is disclosed. In that technology, it is assumed that the capacity (reversible capacity) of the lithium ion battery will gradually decrease according to the root rule as the cumulative use period elapses from the beginning of the life of the lithium ion battery (at the start of use of the lithium secondary battery). However, a decrease in the reversible capacity of the lithium ion battery is predicted using a root-law proportional relationship between the cumulative use period from the beginning of the life and the reversible capacity.

Regarding the battery, Patent Document 1 describes it as a lithium secondary battery and Non-Patent Document 1 describes it as a lithium ion battery, but these are hereinafter referred to as lithium ion secondary batteries.

The technologies described in Patent Document 1 and Non-Patent Document 1 are based on the premise that there is a proportional relationship between the cumulative use period from the beginning to the end of the life of a lithium ion secondary battery and the reversible capacity. Yes.

Japanese Patent Application Laid-Open No. 2017-054692 (Patent Document 2) discloses an invention relating to a power storage system using a secondary battery (lithium ion secondary battery). Patent Document 2 discloses a technique for detecting a scale indicating the deterioration state of the positive electrode and a scale indicating the deterioration state of the negative electrode, and claim 1 states that “the control system of the secondary battery is a deterioration of the positive electrode. Means for detecting a scale indicating the state; means for detecting a scale indicating the deterioration state of the negative electrode; means for calculating a difference between the scale of the positive electrode and the scale of the negative electrode; and determining a sign of the difference And means for changing the operating condition of the secondary battery in accordance with the reference sign ”.

Regarding the above technique, paragraph 0029 of Patent Document 2 states that “the present inventor has noticed that in this mechanism of battery capacity reduction, the positive electrode capacity QP after deterioration and the negative electrode capacity QN after deterioration reverse. As a result, it was found that the battery performance was significantly reduced in a shorter period of time than the expected life. " In order to monitor these measures, a means for measuring or calculating the deteriorated positive electrode potential curve VP and the deteriorated positive electrode potential curve VN is required. By using a means for measuring the potentials of the positive electrode and the negative electrode by inserting the third pole, the battery voltage VB after deterioration, the battery voltage after deterioration from the initial positive electrode potential curve VP0 and the initial negative electrode potential curve VN0 A known technique can be used such as a calculation means, etc. The initial positive electrode potential curve VP0 and the initial negative electrode potential curve VN0 are obtained in advance by charging / discharging with the positive electrode, the negative electrode, or the single electrode, respectively. There is a description. That is, in the technique described in Patent Document 2, in order to detect that the positive electrode capacity after deterioration and the negative electrode capacity after deterioration are reversed, the deterioration state (potential) of the positive electrode and the negative electrode is determined using the reference electrode. Measure or estimate from battery voltage during charge / discharge.

JP 2003-178812 A JP 2017-054692 A

The conventional techniques described in Patent Document 1 and Non-Patent Document 1 have a drawback in that the tendency to decrease the reversible capacity when a lithium ion secondary battery is used over a long period cannot be accurately predicted. The reason is that the cause of the decrease in the reversible capacity of the lithium ion secondary battery includes the deterioration of the negative electrode and the deterioration of the positive electrode. More specifically, the decrease in the reversible capacity of the lithium ion secondary battery may be caused mainly by the deterioration of the negative electrode or the deterioration of the positive electrode, depending on the respective cases. The trend of decline is different. Therefore, a complete proportional relationship is not established between the cumulative use period from the beginning of the life (BOL, Beginning Of Life) to the end of the life (EOL, End Of Life) and the reversible capacity.

More specifically, although it depends on the composition of each material of the positive electrode and the negative electrode of the lithium ion secondary battery, generally, at the start of use of the lithium ion secondary battery, the irreversible capacity of the positive electrode is larger than the irreversible capacity of the negative electrode. Many. The speed of deterioration of the negative electrode (increase in irreversible capacity) is faster than the speed of deterioration of the positive electrode (increase in irreversible capacity). Therefore, the irreversible capacity of the positive electrode is larger than the irreversible capacity of the negative electrode during the initial or middle period of the lithium ion secondary battery, but after a certain point (hereinafter referred to as a transition point), the irreversible capacity of the negative electrode is higher than that of the positive electrode. More than irreversible capacity. That is, the decrease in the reversible capacity of the lithium ion secondary battery is mainly related to the irreversible capacity of the positive electrode in the initial to middle period of the life, but is mainly related to the irreversible capacity of the negative electrode after the transition point. Further, the fact that the speed of deterioration differs between the positive electrode and the negative electrode means that the tendency of the reversible capacity to decrease is different before and after the transition point. Therefore, the deterioration tendency of the lithium ion secondary battery obtained based on the conventional approximation method (that is, a method for deriving an approximate linear function based on all measured values from the BOL) is There is a drawback that the life of a lithium ion secondary battery cannot be accurately predicted because it deviates from the tendency of deterioration.

Further, in the prior art described in Patent Document 1 and Non-Patent Document 1, when the pole that is the main cause of the decrease in the reversible capacity of the lithium ion secondary battery has shifted from one pole to the other pole That is, when the degree of deterioration (irreversible capacity) of the other pole, which was initially low, is higher than the degree of deterioration of one pole (irreversible capacity), which was initially high, the time point (transition point) becomes higher. There are also disadvantages that cannot be easily identified.

In addition, although the term indicating the period such as the initial stage, the middle period, and the end stage of the life is used here, these terms are merely used to represent the period relatively, and the length of the period, the start point, the end point It does not strictly specify the time.

Further, in the configuration for obtaining a scale indicating the deterioration state of the positive electrode and the negative electrode in the prior art as described in Patent Document 2, the deterioration state (potential) of the positive electrode and the negative electrode is measured using the reference electrode, Or it is estimated from the battery voltage at the time of charging / discharging, but there is a disadvantage that the configuration of the device becomes complicated when using the reference electrode, and when it is estimated from the voltage of the battery at charging / discharging, an accurate value is obtained. There are disadvantages that cannot be obtained.

That is, the conventional technology has a drawback that it is not possible to accurately and easily determine the transition point of the tendency to decrease the reversible capacity during the use of the lithium ion secondary battery. That is, the conventional technique has a drawback that it cannot be determined which reversible capacity of the positive electrode or the negative electrode is large, and therefore, it is not possible to determine whether the capacity dominant electrode of the lithium ion secondary battery is the positive electrode or the negative electrode.

Here, the capacity-dominating electrode is the electrode that determines the reversible capacity of the lithium ion secondary battery, ie, the electrode having the smaller reversible capacity between the positive electrode and the negative electrode. Is defined as

Furthermore, for example, there is a drawback that it is not possible to realize a configuration in which various control according to each period is performed by distinguishing between a period in which the main reason for the decrease in reversible capacity is the reversible capacity of the negative electrode and a period in which the positive electrode is reversible. .

Therefore, in the present invention, when the pole that is the main cause of the decrease in the reversible capacity of the lithium ion secondary battery has shifted from one pole to the other, that is, the degree of deterioration of one pole that was initially low. When the (irreversible capacity) becomes higher than the degree of deterioration of the other pole (irreversible capacity) (transition point), that is, the reversible capacity of one pole that was initially large is less than the reversible capacity of the other pole. The time point is obtained based on the characteristics of the open circuit voltage (OCV) in the charge / discharge rest period after the discharge period of the charge / discharge cycle of the lithium ion secondary battery.

Furthermore, in the present invention, after obtaining the transition point, the lifetime is predicted based on the behavior of the lithium ion secondary battery after the transition point. Furthermore, in the present invention, in order to maximize the performance of the lithium ion secondary battery after the transition point, the control of the system related to charging / discharging of the lithium ion secondary battery is changed.

According to a first aspect of the present invention, there is provided a diagnostic apparatus for a secondary battery that detects a capacity dominant electrode that determines a reversible capacity of a secondary battery having a positive electrode and a negative electrode. And a secondary battery diagnostic device having a detection means for detecting a capacity-dominating electrode that determines the reversible capacity of the secondary battery by determining which one of the reversible capacities of the secondary battery and the negative electrode is large. In the secondary battery diagnostic method for detecting a capacity-dominated electrode that determines the reversible capacity of the battery, the secondary battery diagnostic method determines whether the reversible capacity of the positive electrode or the reversible capacity of the negative electrode is larger. A method for diagnosing a secondary battery, comprising a detection step of detecting a capacity dominant electrode that determines the reversible capacity of the battery.

According to a second aspect of the present invention, in the diagnostic apparatus for a secondary battery according to the first aspect, the detection means is a secondary battery that is after the discharge of the charge / discharge cycle of the secondary battery is stopped and during the charge / discharge stop period. Diagnostic device for secondary battery, or diagnosis for secondary battery of first mode, which determines which of reversible capacity of positive electrode and reversible capacity of negative electrode is larger based on voltage characteristics of open circuit voltage (OCV) In the method, the detecting step includes the reversible capacity of the positive electrode based on the voltage characteristics of the open circuit voltage (OCV) of the secondary battery after the discharge stop of the charge / discharge cycle of the secondary battery and during the charge / discharge stop period. This is a secondary battery diagnostic method for determining which of the reversible capacities of the negative electrode is larger.

According to a third aspect of the present invention, in the secondary battery diagnostic apparatus according to the second aspect, the detection means is a secondary battery that is after the charge / discharge cycle of the secondary battery is stopped and during the charge / discharge stop period. As a voltage characteristic of the open circuit voltage (OCV), a measurement unit for measuring an open circuit voltage (OCV) after the elapse of a predetermined period after the discharge of the charge / discharge cycle of the secondary battery is stopped, a reversible capacity of the positive electrode and a negative electrode A voltage value set in advance as a value of an open circuit voltage (OCV) after the elapse of a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery when the reversible capacities coincide, and measured by the measurement unit A secondary battery diagnostic device, or a secondary battery according to the second aspect, comprising: a comparison unit that compares open circuit voltage (OCV) after a predetermined period of time has elapsed since the discharge of the charge / discharge cycle of the secondary battery is stopped In the battery diagnosis method, the detection step includes: The voltage characteristic of the open circuit voltage (OCV) of the secondary battery after the discharge stop of the charge / discharge cycle of the secondary battery and during the charge / discharge stop period is a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery. A measurement step of measuring a subsequent open circuit voltage (OCV) と, and an open circuit voltage after a lapse of a predetermined period after the discharge of the charge / discharge cycle of the secondary battery when the reversible capacity of the positive electrode and the reversible capacity of the negative electrode coincide with each other The voltage value set in advance as the value of (OCV) is compared with the open circuit voltage (OCV) measured in the measurement step and after the elapse of a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery. A diagnostic method for a secondary battery including a comparison step.

According to a fourth aspect of the present invention, in the diagnostic apparatus for a secondary battery of the second aspect, the open circuit voltage of the secondary battery after the discharge stop of the charge / discharge cycle of the secondary battery and during the charge / discharge stop period ( (OCV) voltage characteristic is the speed of recovery of the open circuit voltage (OCV) within a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery, and the detection means is the charge / discharge of the secondary battery. The reversible capacity of the positive electrode and the reversible capacity of the negative electrode coincide with the means for determining the speed of recovery of the open circuit voltage (OCV) within a predetermined period after the cycle discharge is stopped A value of a speed set in advance as a value of a speed of recovery of the open circuit voltage (OCV) within a predetermined period after the discharge of the charge / discharge cycle of the secondary battery is stopped, The open circuit voltage within a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery ( CV) means for comparing with the value of the recovery speed, or in the secondary battery diagnostic method according to the second aspect, in the secondary battery diagnostic method, discharge of the secondary battery charge / discharge cycle The voltage characteristic of the open circuit voltage (OCV) of the secondary battery after the stop and during the charge / discharge stop period is the recovery of the open circuit voltage (OCV) within a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery. And the detecting step obtains a value of a speed of recovery of the open circuit voltage (OCV) within a predetermined period after the discharge of the charge / discharge cycle of the secondary battery is stopped, and the secondary battery In the process of battery deterioration, the speed of recovery of the open circuit voltage (OCV) within a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery when the reversible capacity of the positive electrode and the reversible capacity of the negative electrode coincide. The value of the speed set in advance as the value of and the obtained secondary And comparing the speed of the value of recovery of the open circuit voltage within a predetermined period after discharge stop of the charging and discharging cycle of the pond (OCV), is a diagnostic method for a secondary battery.

According to a fifth aspect of the present invention, in the diagnostic apparatus for a secondary battery according to any one of the first to fourth aspects,
A secondary battery having determination means for determining a transition point at which a capacity dominant electrode that determines a reversible capacity of the secondary battery has shifted from one of a positive electrode and a negative electrode to the other in the course of deterioration of the secondary battery. Diagnostic equipment. In the secondary battery diagnostic method according to any one of the first to fourth aspects, the capacity-dominating electrode that determines the reversible capacity of the secondary battery in the course of deterioration of the secondary battery is a positive electrode and a negative electrode. It is the diagnostic method of a secondary battery which has the determination step which determines the transition point which transfered from either one to the other.

According to a sixth aspect of the present invention, in the diagnostic device for a secondary battery according to the fifth aspect, the capacity dominant electrode that determines the reversible capacity of the secondary battery in the course of deterioration of the secondary battery is a positive electrode and a negative electrode. In the secondary battery diagnostic apparatus or the secondary battery diagnostic method according to the fifth aspect, the secondary battery is deteriorated in which the transition point from any one of the above is indicated by the cumulative number of charge / discharge cycles. A method for diagnosing a secondary battery, wherein a transition point at which the capacity-dominating electrode that determines the reversible capacity of the secondary battery in the process has shifted from either the positive electrode or the negative electrode to the other is indicated by the number of accumulated charge / discharge cycles. .

According to a seventh aspect of the present invention, in the fifth or sixth secondary battery diagnostic apparatus, the capacity-dominating electrode that determines the reversible capacity of the secondary battery in the course of deterioration of the secondary battery is a positive electrode. And a secondary battery having a life prediction means for detecting a time change in the deterioration state of the secondary battery after the transition point from one of the negative electrode and the negative electrode to the other and predicting the life performance of the secondary battery. In the diagnostic method for a secondary battery of the fifth or sixth aspect, the capacity-dominating electrode that determines the reversible capacity of the secondary battery in the course of deterioration of the secondary battery further comprises a positive electrode and a negative electrode. A method for diagnosing a secondary battery, comprising a life prediction step for detecting a time change in the deterioration state of the secondary battery after a transition point from one to the other and predicting the life performance of the secondary battery It is.

According to an eighth aspect of the present invention, in the secondary battery control system including the diagnostic apparatus for the secondary battery according to the fifth to seventh aspects, the reversible capacity of the secondary battery is determined in the course of deterioration of the secondary battery. A secondary battery control system, or a fifth to seventh aspect, having a control means for changing the control of the secondary battery at a transition point where the capacity-dominating electrode to be shifted from one of the positive electrode and the negative electrode to the other In the secondary battery control method including the secondary battery diagnosis method, the capacity-dominating electrode that determines the reversible capacity of the secondary battery in the course of deterioration of the secondary battery is changed from one of the positive electrode and the negative electrode to the other. It is a secondary battery control method which has the control step which changes the control with respect to the said secondary battery in the transition point which shifted to (1).

According to a ninth aspect of the present invention, there is provided a secondary battery charging apparatus including the secondary battery diagnostic apparatus according to the first to seventh aspects, or a secondary battery diagnostic method according to the first to seventh aspects. A battery charging method.

A tenth aspect of the present invention is a program for executing the diagnostic method for a secondary battery according to the first to seventh aspects. An eleventh aspect of the present invention is a secondary battery according to the first to seventh aspects. This is a recording medium on which a program for executing the diagnostic method is recorded.

The use of the present invention has an effect of accurately and easily discriminating a point (transition point) at which a pole that is a main cause of a decrease in reversible capacity of a lithium ion secondary battery has shifted from one pole to the other. That is, according to the present invention, it is possible to determine which reversible capacity between the positive electrode and the negative electrode is large, and therefore, it is possible to determine whether the capacity dominant electrode of the lithium ion secondary battery is the positive electrode or the negative electrode. Further, by using the present invention, there is an effect that the configuration of the diagnostic apparatus can be simplified. Moreover, in this invention, there exists an effect which can estimate the lifetime of a lithium ion secondary battery correctly based on the reduction | decrease in the reversible capacity | capacitance of the secondary battery after a transition point. Furthermore, in the present invention, it is possible to distinguish between a period in which the reversible capacity of the secondary battery is reduced and a period in which it is a negative electrode from a period in which it is a positive electrode. Therefore, for example, it is possible to realize a configuration that performs various controls according to each period. There is.

FIG. 1 is a graph showing the relationship between the reversible capacity of a lithium ion secondary battery and the number of charge / discharge cycles when the lithium ion secondary battery is charged and discharged at 1C at 25 ° C. FIG. 2 is a graph showing the relationship between the OCV of the lithium ion secondary battery immediately after the 10 minute charge / discharge suspension period after the discharge period in the charge / discharge cycle and the number of charge / discharge cycles. FIG. 3 shows the OCV of the lithium ion secondary battery during the 10-minute charge / discharge rest period after the discharge period during the second, 200th, 400th, and 600th charge / discharge cycles. It is a graph which shows the relationship with time. FIG. 4 schematically shows the configuration of the diagnostic apparatus according to the embodiment of the present invention. FIG. 5 is a flowchart showing the operation of the diagnostic apparatus in the first embodiment. FIG. 6 is a flowchart showing the operation of the diagnostic apparatus in the second embodiment. FIG. 7 is a flowchart showing the operation of the diagnostic apparatus in the third embodiment. FIG. 8 is a graph showing the relationship between the capacity retention rate and the number of charge / discharge cycles when the lithium ion secondary battery is charged at 25 ° C. at 1 C and then discharged at 0.2 C. FIG. 9 is a graph showing the relationship between the capacity retention rate and the number of charge / discharge cycles when the lithium ion secondary battery is charged at 25 ° C. and 1 C and then discharged at 0.2 C.

In the process of reaching the present invention, experiments were conducted under the following conditions.

(1) Lithium ion secondary battery to be used: 600 mAh class Positive electrode Double-sided coated positive electrode: 92 mm x 92 mm x 2 sheets LiNi1 / 3Co1 / 3Mn1 / 3O2 (92 wt%), carbon black (4 wt%), PVdF (4 wt%)
After coating 14mg / cm ² on one side to 24μm Al foil, press and vacuum-dry. Negative electrode Double-sided graphite negative electrode: 94mm x 94mm x 3 sheets Graphite (95wt%), SBR (2.5wt%), CMC ( 2.5wt%)
A single-side coating amount of 8.5 mg / cm ² is applied to a 12 μm Cu foil, then pressed and vacuum dried.
・ Separator 3DOM PI (polyimide) separator: 96mm × 96mm × 4 sheets ・ Electrolytic solution Insert the power generation element with the above layers into an aluminum laminate outer package, and add 6ml of 1M LiPF6 / EC + DEC (3: 7) Liquid and sealed.

(2) Conditions for charge / discharge cycle test at 25 ° C. and 600 mA Charging: 600 mA-4.2 V, CCCV (30 mA)
Charging pause: 10 minutes Discharging: 600mA-2.8V, (CC)
Discharge pause: 10 minutes.

(3) Conditions for capacity confirmation test at 25 ° C. and 120 mA Charging: 120 mA-4.2 V, CCCV (6.5 h)
Charging pause: 10 minutes Discharging: 120mA-2.8V, CC
Discharge pause: 10 minutes Implemented every 250 cycles at 600 mA charge / discharge cycle.

BOL is the time before the start of use of the lithium ion secondary battery, and EOL is the time when the capacity maintenance rate of 80% cannot be maintained. In addition, the capacity-dominating electrode at the time of BOL is the positive electrode. The discharge end voltage (minimum open circuit voltage) is 2.8V. The voltage at the start of discharge (maximum open circuit voltage) is 4.2V. Hereinafter, the open circuit voltage is referred to as OCV.

FIG. 1 is a graph showing the relationship between the reversible capacity of a lithium ion secondary battery and the number of charge / discharge cycles when the lithium ion secondary battery is charged and discharged at 1C at 25 ° C. The vertical axis represents the reversible capacity (mAh) of the lithium ion secondary battery, and the horizontal axis represents the number of charge / discharge cycles as its square root. The solid line in the graph of FIG. 1 is drawn based on measured values, and the dotted line indicates a function that most closely approximates the relationship between these measured values. This function was y = −1.8898x + 6533.21, and the coefficient of determination (R ² ) between this function and the measured value was 0.9758.

In the solid line portion of the graph of FIG. 1, there was an inflection point (corresponding to the above transition point) at the position where the number of charge / discharge cycles was about 400 (20 on the horizontal axis). That is, when the pole that affects the reversible capacity of the lithium ion secondary battery, that is, when the capacity-dominating pole is shifted from one pole (positive electrode) to the other pole (negative electrode), the number of charge / discharge cycles is about 400 times. It turns out that it is the time.

Further, in the experiment, the OCV of the lithium ion secondary battery immediately after the 10-minute charge / discharge pause period after the discharge period in the charge / discharge cycle is measured every predetermined charge / discharge cycle, and during the 10-minute pause period. The OCV of the lithium ion secondary battery was measured in correspondence with time.

FIG. 2 is a graph showing the relationship between the OCV of the lithium ion secondary battery immediately after the 10-minute charge / discharge pause period after the discharge period in the charge / discharge cycle and the number of charge / discharge cycles. FIG. 3 shows the OCV of the lithium ion secondary battery during the 10-minute charge / discharge rest period after the discharge period during the second, 200th, 400th, and 600th charge / discharge cycles. It is a graph which shows the relationship with time.

2, the vertical axis indicates OCV (V) immediately after the 10-minute charge / discharge pause period after the discharge period, and the horizontal axis indicates the number of charge / discharge cycles as its square root. As shown in the graph of FIG. 2, the OCV is proportionally decreased until around the 400th charge / discharge cycle (20 on the horizontal axis of the graph), but is constant from around the 400th charge / discharge cycle. The value is close to the value. That is, it can be understood from this graph that the charge / discharge characteristics of the lithium ion secondary battery changed around the 400th charge / discharge cycle.

3, the vertical axis represents OCV (V) of the lithium ion secondary battery, and the horizontal axis represents time (seconds). When the time is 0, that is, immediately after the end of the discharge period, the specified minimum OCV (2.8 V) is obtained. Thereafter, the OCV of the lithium ion secondary battery naturally recovers a little during 10 minutes until the charging period starts. This graph shows the characteristics of the voltage recovery. Further, in this graph, the curve related to the 400th charge / discharge cycle and the curve related to the 600th charge / discharge cycle substantially overlap each other, and therefore, it is represented as one curve.

From the graph of FIG. 3, regarding the OCV at 600 seconds (10 minutes), the one related to the second charge / discharge cycle is the largest, and gradually decreases until the 400th charge / discharge cycle. It can be understood that the charge and discharge cycles after the 400th charge are substantially constant. That is, it can be understood from this graph that the charge / discharge characteristics of the lithium ion secondary battery changed around the 400th charge / discharge cycle as in the graph of FIG. 2.

1 From the graph of FIG. 1 and each of the graphs of FIG. 2 and FIG. 3, it was derived that the same result, that is, the changing point of the graph was around the 400th charge / discharge cycle. From this result, the change in the charge / discharge characteristics of the lithium ion secondary battery shown in the graphs of FIG. 2 and FIG. 3 was transferred from one electrode (positive electrode) to the other electrode (negative electrode). I can understand that

Next, an embodiment (first embodiment) for determining the time point (transition point) at which the capacity-dominated electrode of the lithium ion secondary battery has shifted from one electrode to the other electrode will be described. In 1st Embodiment, after the discharge stop of the charging / discharging cycle of a secondary battery, and the voltage characteristic of the open circuit voltage of the secondary battery in a charging / discharging stop period, the predetermined after the discharge stop of the charging / discharging cycle of a secondary battery By measuring the open circuit voltage (OCV) after the lapse of the period, the transition point from the positive electrode to the negative electrode (cumulative charge / discharge cycle number), that is, the above transition point is determined. In this embodiment, a predetermined charging / discharging suspension period is 10 minutes, and a predetermined time point in the predetermined charging / discharging suspension period is a time point of 10 minutes.

FIG. 4 schematically shows a configuration of a diagnostic apparatus for determining a transition point. The diagnosis device 1 that determines the transition point includes an input / output unit 2 that inputs and outputs data, a predetermined voltage (reference OCV determined by an experiment or the like) corresponding to the transition point, and the number of charge / discharge cycles performed (cumulative charge / discharge cycle). The storage unit 3 that stores the number of times of a predetermined charge / discharge cycle to be measured, and the OCV immediately after the charge / discharge pause period of 10 minutes after the discharge period at the time of the predetermined charge / discharge cycle It includes a measurement unit 4 that measures (measurement OCV), a comparison unit 5 that compares the reference OCV with the measurement OCV, and a control unit 6 that controls these units. The measurement unit 4 and the comparison unit 5 may be collectively referred to as detection means. FIG. 5 is a flowchart showing the operation of the diagnostic apparatus in the first embodiment. This diagnostic apparatus may be realized by a program based on this flowchart. The operation of this diagnostic apparatus will be described with reference to FIG.

The “number of performed charge / discharge cycles (cumulative charge / discharge cycle number)” stored in the storage unit is updated every time a charge / discharge cycle is performed. Since such a configuration is well known, a description thereof will be omitted.

In step S1.1, the initial data including the reference OCV determined by an experiment or the like and the number of times of a predetermined charge / discharge cycle in which measurement is performed is stored in the storage unit 3 via the input unit 1. This reference OCV is an open circuit voltage (OCV) after the elapse of a predetermined period after the discharge of the charge / discharge cycle of the secondary battery when the reversible capacity of the positive electrode and the reversible capacity of the negative electrode coincide with each other in the process of deterioration of the secondary battery. ) Value. The number of times of a predetermined charge / discharge cycle in which measurement is performed can be appropriately set. For example, data indicating the number of times of measurement (for example, the 10th time, the 20th time,...). Can be configured, or data indicating the interval of measurement (every time, every 100 times, etc.) can be stored. Further, when the measurement is performed every time, it is not necessary to store “the number of predetermined charge / discharge cycles in which the measurement is performed” in the storage unit 3.

In step S1.2, based on the data stored in the storage unit 3, the control unit 6 determines whether or not the current charging / discharging cycle is a predetermined charging / discharging cycle. When it is determined that it is not a predetermined charge / discharge cycle (No in step S1.2 in FIG. 5), the process waits until the next charge / discharge cycle is performed, and then the charge / discharge cycle is again performed. It is determined whether or not it is a predetermined charge / discharge cycle to be measured.

In step S1.2, when the control unit 6 determines that the current charge / discharge cycle is a predetermined charge / discharge cycle to be measured, the process proceeds to step S1.3.

In step S1.3, the control unit 6 uses the measurement unit 5 to measure an OCV (measurement OCV) at a time point of 10 minutes in a charge / discharge pause period of 10 minutes after the discharge period of the charge / discharge cycle.

Next, in step S1.4, the control unit 6 uses the comparison unit 5 to compare the reference OCV stored in the storage unit 6 with the measurement OCV measured by the measurement unit 4. If the measured OCV is not less than or equal to the reference OCV, the process returns to step S1.2. When the measured OCV is equal to or lower than the reference OCV, the process proceeds to step S1.5, and the control unit 6 determines that the number of times of the charge / discharge cycle is a transition point at which the tendency to decrease the reversible capacity changes. That is, the control unit 6 determines that the time point of the charge / discharge cycle is the time point when the capacity dominant electrode has shifted from one electrode to the other electrode.

In addition, in 1st Embodiment, although the time of measuring OCV was set as 10 minutes after a discharge period, the time of measuring OCV is not limited to this. For example, based on the graph of FIG. 3, after a certain amount of time has elapsed from the end of the discharge period, the difference in OCV after each charge / discharge cycle becomes clear. Therefore, the OCV at any time may be used as long as the difference in OCV after each charge / discharge cycle becomes clear.

The above is the operation of the diagnostic apparatus for determining the transition point in the first embodiment. The storage unit stores a program that causes the diagnostic apparatus to perform the above operation.

Next, another embodiment (second embodiment) for determining the time point (transition point) at which the capacity-dominated electrode of the lithium ion secondary battery has shifted from one pole to the other will be described. In the second embodiment, the transition point is determined based on the OCV increase rate (ΔOCV) in a predetermined period during the charge / discharge suspension period after the end of the discharge period of the charge / discharge cycle.

The diagnostic device of the second embodiment has the same hardware configuration as the diagnostic device of the first embodiment, but the OCV measurement method is different from the comparison target used when determining the transition point. Each unit of the diagnostic apparatus has a configuration corresponding to them.

In the second embodiment, the predetermined period after the end of the discharge period is 30 seconds from the time point 10 seconds later to the time point 40 seconds later, and the rate of increase in OCV per second in that 30 seconds is compared. . Accordingly, the storage unit 3 stores the OCV increase rate (reference ΔOCV) determined by experiments or the like. This reference ΔOCV is the value of the open circuit voltage (OCV) within a predetermined period after the discharge of the charge / discharge cycle of the secondary battery when the reversible capacity of the positive electrode and the reversible capacity of the negative electrode coincide with each other in the process of deterioration of the secondary battery. ) Recovery speed value. The measurement unit 4 includes a configuration for measuring the OCV for 30 seconds from 10 seconds to 40 seconds after the end of the discharge period. Further, the comparison unit 5 further calculates the OCV increase rate (measurement ΔOCV) per second for 30 seconds based on the 30-second OCV measured by the measurement unit 4, and the reference ΔOCV. A configuration for comparing the measured ΔOCV is provided. The control unit 6 has a configuration for controlling these units. FIG. 6 is a flowchart showing the operation of the diagnostic apparatus in the second embodiment. The operation of this diagnostic apparatus will be described with reference to FIG.

In step S2.1, the initial data including the reference ΔOCV determined by an experiment or the like and the number of times of a predetermined charge / discharge cycle for measurement is stored in the storage unit 3 via the input / output unit 2. About the time of the predetermined charging / discharging cycle which performs a measurement, it is possible to set suitably like step S1.1.

In step S2.2, the control unit 6 determines whether or not the current charging / discharging cycle is a predetermined charging / discharging cycle in which the measurement is performed, based on the data stored in the storage unit. When it is determined that it is not a predetermined charge / discharge cycle (No in step S2.2 in FIG. 6), the process waits until the next charge / discharge cycle is performed, and then the charge / discharge cycle is again performed. It is determined whether or not it is a predetermined charge / discharge cycle to be measured.

In step S2.2, when the control unit 6 determines that the current charge / discharge cycle is a predetermined charge / discharge cycle to be measured, the process proceeds to step S2.3.

In step S2.3, the control unit 6 uses the measurement unit 4 to measure the OCV for 30 seconds from the time point of 10 seconds to the time point of 40 seconds during the charge / discharge suspension period after the discharge period of the charge / discharge cycle. To do.

In step S2.4, the control unit 6 uses the calculation means of the comparison unit to calculate the rate of increase of OCV per second (measurement ΔOCV) from the OCV measured for 30 seconds.

Next, in step S2.5, the control unit 6 uses the comparison unit 5 to compare the reference ΔOCV stored in the storage unit 3 with the measured ΔOCV calculated by the calculation unit of the comparison unit 5. If the measurement ΔOCV is not less than or equal to the reference ΔOCV, the process returns to step S2.2. When the measurement ΔOCV is equal to or smaller than the reference ΔOCV, the process proceeds to step S2.6, and the control unit 6 determines that the charge / discharge cycle is a transition point at which the tendency to decrease the reversible capacity changes. That is, the control unit 6 determines that the time point of the charge / discharge cycle is the time point when the capacity dominant electrode has shifted from one electrode to the other electrode.

In the second embodiment, the OCV measurement period for obtaining ΔOCV is 30 seconds from the 10 second time point to the 40 second time point in the charge / discharge pause period after the end of the discharge period. Is not limited to this. The OCV measurement period for obtaining ΔOCV may be any period as long as the difference in ΔOCV during the charge / discharge suspension period after each charge / discharge cycle becomes clear.

The above is the operation of the diagnostic apparatus for determining the transition point in the second embodiment. The storage unit stores a program that causes the diagnostic apparatus to perform the above operation.

In the above embodiment, as a method of determining the transition point of the capacity dominant electrode of the lithium ion secondary battery in use, the voltage (reference OCV) and the voltage increase rate (ΔOCV), that is, the standard, are experimentally determined. Although a method of obtaining a numerical value (reference value) in advance and storing it in the storage unit and comparing the reference value with the actual measurement value is used, other methods are also possible.

For example, the transition point of a lithium ion secondary battery in use can also be determined. When using OCV as in the first embodiment, [first step] at the predetermined number of charge / discharge cycles, after the discharge period The OCV is measured at a time point of 10 minutes in the 10-minute charge / discharge suspension period, and [Second Step] each OCV up to a predetermined measurement number from the latest measured OCV (a predetermined number of OCVs in the past). ) Is within a predetermined deviation of the average value of those OCVs. [Third Step] When a predetermined number of past OCVs are within a predetermined deviation of the average value of those OCVs, The time (number of charge / discharge cycles) at which the oldest OCV is measured can be determined as the transition point. Even when ΔOCV is used as in the second embodiment, the transition point of the lithium ion secondary battery in use can be determined in the same manner as described above. In addition, in such a structure, there exists a fault that the time at which a transition point is determined will be delayed a little.

Next, a configuration for predicting the EOL of the lithium ion secondary battery (third embodiment) will be described. In the present invention, when predicting the EOL of a lithium ion secondary battery, the transition obtained by the present invention is used instead of using all the measured values from the beginning of the use of the lithium ion secondary battery as in the prior art. Use the measured value after the point.

The diagnosis device of the third embodiment is similar in hardware configuration to the diagnosis device of the first embodiment or the second embodiment, but the measuring unit 4 is a predetermined lithium ion secondary battery after the transition point. It has a configuration for measuring or estimating the reversible capacity immediately after the charging period of the charge / discharge cycle, and the storage unit 3 is further measured or estimated as the reversible capacity (initial reversible capacity) at the BOL of the lithium ion secondary battery. The reversible capacity and the charge / discharge cycle times (cumulative charge / discharge cycle count) are stored, and the calculation means of the comparison unit 5 is further measured or estimated as the initial reversible capacity stored in the storage unit 3. A configuration for calculating the capacity maintenance rate based on the reversible capacity, and a configuration using the relationship between the capacity maintenance rate and the cumulative number of charge / discharge cycles as a function. FIG. 7 is a flowchart showing the operation of the diagnostic apparatus in the third embodiment. Hereinafter, the operation of the diagnostic apparatus will be described with reference to FIG.

In addition, although 3rd Embodiment includes the structure of 1st Embodiment or 2nd Embodiment as a structure which determines a transition point, since the structure has already been demonstrated, it abbreviate | omits here.

In step S3.1, the reversible capacity (initial reversible capacity) of the lithium ion secondary battery during BOL is stored in the storage unit 3 via the input / output unit 2. In step S3.1, data stored in step S1.1 of the first embodiment or step S2.1 of the second embodiment is also stored, but the description is omitted in FIG.

Step S3.2 includes the same steps as steps S1.2 to S1.4 of the first embodiment or steps S2.2 to S2.5 of the second embodiment. That is, it is determined whether or not the time point of the charge / discharge cycle, which is the target of measurement or estimation of the reversible capacity, is the time point when the capacity dominant electrode has shifted from one pole to the other, that is, the transition point. In step S3.2, when it is determined that the time point of the charge / discharge cycle that is the target of measurement or estimation of the reversible capacity is the transition point, the process proceeds to step S3.3.

In step S3.3, the control unit 6 uses the measurement unit 4 to measure or estimate the reversible capacity immediately after the charging period of the predetermined charging / discharging cycle after the transition point, and to perform the measurement or estimation. The number of discharge cycles (cumulative charge / discharge cycle count) and the measured or estimated reversible capacity are associated with each other and stored in the storage unit 3.

In step S3.4, the control unit 6 uses the calculation unit of the comparison unit 5 to calculate each charge / discharge cycle based on the initial reversible capacity stored in the storage unit 3 and the measured or estimated reversible capacity. The capacity maintenance rate is calculated for the number of times (cumulative charge / discharge cycle number).

In step S3.5, the control unit 6 has a relationship between the plurality of cumulative charge / discharge cycle times and the plurality of capacity maintenance rates when a set of a predetermined number of cumulative charge / discharge cycles and the capacity maintenance rate is completed. A function (linear function) that is most approximated to Y = aX + b (Y is a capacity maintenance rate, and X is a cumulative number of charge / discharge cycles) is derived. Regression analysis can be used to obtain this function, but details of the regression analysis are well known, and therefore description thereof is omitted here.

In step S3.6, the control unit 6 obtains the cumulative number of charge / discharge cycles during EOL of the lithium ion secondary battery using the function obtained in step S3.5. In this embodiment, the EOL is set at a point when the capacity maintenance rate of 80% cannot be maintained. Therefore, the accumulated charge / discharge cycle number at the time of EOL (when the capacity maintenance ratio becomes 80%) can be obtained by using the derived linear function, Y = aX + b, Y = 80, a = constant, and b = 100.

In the third embodiment, the reversible capacity of a predetermined charge / discharge cycle after the transition point is measured or estimated. However, the reversible capacity may be measured from the BOL time of the lithium ion secondary battery. Well, in that case, when deriving a function that most closely approximates the relationship between the number of cumulative charge / discharge cycles and the capacity retention ratio, simply use the reversible capacity measured or estimated after the transition point. What is necessary is just to comprise.

The above is the operation of the diagnostic apparatus for predicting the EOL of the lithium ion secondary battery in the third embodiment. The storage unit stores a program that causes the diagnostic apparatus to perform the above-described operation.

Hereinafter, with reference to FIG. 8 and FIG. 9, an explanation will be given to clarify the difference between the EOL required by the third embodiment and the EOL required by the conventional technique.

FIG. 8 and FIG. 9 are graphs showing the relationship between the capacity retention rate and the number of charge / discharge cycles when the lithium ion secondary battery is charged at 25 ° C. and 1 C and then discharged at 0.2 C. In the graph, the vertical axis indicates the capacity maintenance rate (%), and the capacity maintenance rate in a fully charged state when the lithium ion secondary battery is first used is 100%. The horizontal axis indicates the number of charge / discharge cycles, and the number is shown as the square root of the number. For example, 20 on the horizontal axis of the graph represents 400 times.

8 and 9, each of the plurality of points indicated by “◯” is an actually measured point (hereinafter referred to as a measurement point). For example, the second circle from the left side of the graph of FIG. 8 indicates that the capacity maintenance rate was about 99% when the number of charge / discharge cycles was about 250, and the third circle from the left side was It indicates that the capacity retention rate was about 97.5% when the number of charge / discharge cycles was about 500.

The dotted straight line in the graph of FIG. 8 represents a function that is most approximated to the relationship between the measurement points derived based on all the measurement points from the time point when the number of cycles is zero. Thus, the method of deriving a function based on all measurement points from the BOL is the method of the prior art described in the above “Background Art”. The function obtained by this conventional technique was y = −0.17x + 100. The coefficient of determination (R ² ) between this function and the measurement point was 0.8437.

Based on this function y = −0.17x + 100, when the capacity retention rate reaches 80%, that is, when the specified EOL is reached, the number of charge / discharge cycles exceeds 6400 (80 on the horizontal axis of the graph). This is expected to be a long time ago.

FIG. 9 shows a plurality of measurement points after the point (transition point) at which the behavior of the lithium ion secondary battery obtained according to the present invention is changed among the measurement points shown in FIG. In this example, the transition point of the tendency to decrease the reversible capacity of the lithium ion secondary battery is when the number of charge / discharge cycles is about 400. Therefore, the two measurement points on the left of the plurality of measurement points shown in FIG. 8 are not shown in FIG. 9 because they are before the number of charge / discharge cycles reaches 400.

A dotted straight line in FIG. 9 represents a function that is derived based on the plurality of measurement points shown in FIG. This function was y = −0.3321x + 105.02, and the coefficient of determination (R ² ) between this function and a plurality of measurement points after the transition point was 0.9809.

Based on this function y = −0.3321x + 105.02, when the capacity maintenance rate reaches 80% (indicated by “●” in the graph), that is, when the specified EOL is reached, the number of charge / discharge cycles is Expected to be about 5600 times.

As can be judged from the above determination coefficient, the behavior obtained from the transition point of the tendency of decrease in reversible capacity of the lithium ion secondary battery is better expressed by the function obtained by the technique of the present invention. ing. Therefore, EOL (at the time when the number of charge / discharge cycles is 5600) determined by the technique of the present invention is higher than EOL (at the time when the number of charge / discharge cycles exceeds 6400) determined by the prior art. Theoretically, it is close to the actual EOL.

Note that, based on the function y = −0.3321x + 105.02, the capacity retention rate when the number of charge / discharge cycles is 0 is about 105% (indicated by “●” in the graph of FIG. 9). The capacity maintenance rate of 105% corresponds to the reversible capacity determined based on the irreversible capacity of the negative electrode. In this regard, as described above in “Problem to be Solved by the Invention”, the reversible capacity of the lithium ion secondary battery before the transition point is more influenced by the positive electrode than the negative electrode (the reversible capacity of the positive electrode). Less capacity). Therefore, before the transition point, even if the reversible capacity determined based on the irreversible capacity of the negative electrode is more than the reversible capacity determined based on the irreversible capacity of the positive electrode, the reversible capacity determined based on the irreversible capacity of the positive electrode. The capacity becomes a reversible capacity that can actually be used. That is, the actual reversible capacity when the number of charge / discharge cycles is 0 is a reversible capacity corresponding to the capacity maintenance rate of 100% shown in FIG.

Although the first and second embodiments have been described above, in still another embodiment, the diagnostic device of the first embodiment or the second embodiment is applied in order to keep the lithium ion secondary battery in a good state. be able to. Hereinafter, an application example using the first embodiment will be described.

In order for the control device that controls the use environment of the lithium ion secondary battery to keep the lithium ion secondary battery in a good state, before and after the transition point, that is, the period in which the capacity dominant electrode is the positive electrode and the capacity dominant electrode. It is necessary to perform different control, for example, control for changing the current, temperature, and the like at the time of charge / discharge depending on the period in which the negative electrode is negative. In such a control device, the transition point can be determined by applying the first embodiment or the second embodiment of the present invention. For example, step S1.4 of the first embodiment or the second embodiment In the case of No in step S2.5 of the form, control is performed mainly considering one pole, and in the case of Yes in step S1.4 of the first embodiment or step S2.5 of the second embodiment. The control device can be configured to perform control mainly considering the other pole.

In the above embodiment, the lithium ion secondary battery is used as an example, but the present invention can also be applied to other batteries. Specifically, the present invention relates to a rechargeable battery that accompanies deterioration of the positive electrode and the negative electrode, which is a main cause of a decrease in reversible capacity. One pole is more involved in reducing reversible capacity because it is more degraded than the other pole, but the other pole is faster to degrade than one pole, and both the one pole and the other pole are degraded. Can be applied to a battery having a characteristic that, from a certain point of time, the deterioration of the other electrode is more than the deterioration of the other electrode, and the other electrode is greatly involved in the reduction of the reversible capacity. .

The present invention can be used for diagnosing the state of a battery having the above characteristics.

DESCRIPTION OF SYMBOLS 1 Diagnosis apparatus 2 Input / output part 3 Storage part 4 Measurement part 5 Comparison part 6 Control part

Claims

In the diagnostic apparatus for a secondary battery that detects a capacity-dominated electrode that determines the reversible capacity of a secondary battery having a positive electrode and a negative electrode, the diagnostic apparatus for the secondary battery includes:
Having detection means for detecting a capacity-dominated electrode that determines the reversible capacity of the secondary battery by determining which one of the reversible capacity of the positive electrode and the reversible capacity of the negative electrode is larger,
Secondary battery diagnostic device.
The secondary battery diagnostic device according to claim 1,
The detection means is based on the voltage characteristics of the open circuit voltage (OCV) of the secondary battery after the discharge stop of the charge / discharge cycle of the secondary battery and during the charge / discharge stop period. Determine which of the capacities is greater,
Secondary battery diagnostic device.
The diagnostic apparatus for a secondary battery according to claim 2,
The detection means includes
As a voltage characteristic of the open circuit voltage (OCV) of the secondary battery after the discharge stop of the charge / discharge cycle of the secondary battery and during the charge / discharge stop period, a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery A measurement unit for measuring the open circuit voltage (OCV) after elapse of time;
A voltage value set in advance as a value of an open circuit voltage (OCV) after elapse of a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery when the reversible capacity of the positive electrode and the reversible capacity of the negative electrode coincide with each other; A comparison unit that compares the open circuit voltage (OCV) measured after the predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery measured in the measurement unit,
Secondary battery diagnostic device.
The diagnostic apparatus for a secondary battery according to claim 2,
The voltage characteristic of the open circuit voltage (OCV) of the secondary battery after the discharge stop of the charge / discharge cycle of the secondary battery and during the charge / discharge stop period is a predetermined period after the discharge stop of the charge / discharge cycle of the secondary battery The speed of recovery of the open circuit voltage (OCV) in
The detection means includes
Means for determining a value of a speed of recovery of the open circuit voltage (OCV) within a predetermined period after stopping the discharge of the charge / discharge cycle of the secondary battery;
Recovery of the open circuit voltage (OCV) within a predetermined period after the stop of discharge of the charge / discharge cycle of the secondary battery when the reversible capacity of the positive electrode and the reversible capacity of the negative electrode coincide with each other in the process of deterioration of the secondary battery The speed value set in advance as the speed value and the speed of recovery of the open circuit voltage (OCV) within a predetermined period after the discharge of the charge / discharge cycle of the secondary battery is determined. Including means for comparing the values,
Secondary battery diagnostic device.
The secondary battery diagnostic device according to any one of claims 1 to 4, further comprising:
In a process in which the secondary battery is deteriorated, the capacity dominant electrode that determines the reversible capacity of the secondary battery has a determination unit that determines a transition point from one of the positive electrode and the negative electrode to the other.
Secondary battery diagnostic device.
6. The diagnostic apparatus for a secondary battery according to claim 5, wherein the capacity-dominating electrode that determines the reversible capacity of the secondary battery is transferred from one of the positive electrode and the negative electrode to the other in the course of deterioration of the secondary battery. A diagnostic device for a secondary battery that indicates the transition point by the cumulative number of charge / discharge cycles.
The diagnostic apparatus for a secondary battery according to claim 5 or 6, further comprising:
In the process of deterioration of the secondary battery, the secondary battery is in a deteriorated state after the transition point where the capacity dominant electrode that determines the reversible capacity of the secondary battery has shifted from either the positive electrode or the negative electrode to the other. Having a life prediction means for detecting a time change and predicting a life performance of the secondary battery,
Secondary battery diagnostic device.
A secondary battery control system comprising the secondary battery diagnostic device according to any one of claims 5 to 7,
Control in which the control of the secondary battery is changed when the capacity dominant electrode that determines the reversible capacity of the secondary battery shifts from one of the positive electrode and the negative electrode to the other in the course of deterioration of the secondary battery. Having means,
Secondary battery control system.
A secondary battery charging device including the secondary battery diagnostic device according to any one of claims 1 to 7.
In the secondary battery diagnostic method for detecting a capacity-dominated electrode that determines the reversible capacity of a secondary battery having a positive electrode and a negative electrode, the diagnostic method of the secondary battery includes:
Having a detection step of detecting a capacity dominant electrode that determines the reversible capacity of the secondary battery by determining which one of the reversible capacity of the positive electrode and the reversible capacity of the negative electrode is larger,
Secondary battery diagnostic method.
A program for executing the method according to claim 10.
A recording medium on which a program for executing the method according to claim 10 is recorded.