JP3878397B2 - Secondary battery full charge, battery deterioration degree and dischargeable capacity determination method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a full charge, battery deterioration degree and dischargeable capacity determination method and apparatus for a secondary battery in which an electrode surface such as a lead battery dissolves and precipitates and an inert insulator is generated on the electrode surface. .
[0002]
[Prior art]
Conventionally, in this type of battery full charge determination, a constant multiple (for example, 1.15 times) of the capacity at which the discharge capacity is saturated by repeated charging and discharging several times is used as the full charge point. Until now there was no quantitative measurement method.
As for the degree of deterioration, the above discharge capacity was measured, and the degree of deterioration was calculated by comparison with a new battery.
Furthermore, there has been no suitable method for estimating the dischargeable capacity of a fully charged battery.
[0003]
[Problems to be solved by the invention]
As described above, since there is no quantitative determination method according to the use state and deterioration state of the battery for battery full charge determination, it causes insufficient charge, overcharge, etc., which is preferable from the viewpoint of battery life. There wasn't. Moreover, since it is necessary to repeat charge / complete discharge and several times of charge / discharge in order to determine the capacity change accompanying the deterioration of the battery, it takes about 1 to 2 days and is not efficient.
Furthermore, since charging and discharging cannot be performed easily, the capacity measurement is currently outsourced to a specialized contractor equipped with such equipment.
[0004]
The problem to be solved by the present invention is that the battery full charge determination, the deterioration degree determination and the dischargeable capacity determination can be quantitatively performed, and the optimum charge / discharge management according to the use state of the battery becomes possible. The battery life can be extended, the system can be operated optimally, and the time required for measurement can be greatly reduced.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, in the battery full charge determination, the deterioration degree determination and the dischargeable capacity determination, the behavior of the active material generated on the electrode surface along with charge / discharge, and the electric double layer capacity at the electrode interface associated therewith are determined. Changes, hydrogen generation reactions as side reactions, oxygen generation reactions, and the like are determined by applying a current rectangular pulse to the battery, and the previous behavior is determined by the shape of the voltage waveform.
[0006]
That is, the secondary battery full charge determination method of the present invention is a secondary battery full charge determination method in which the active material of the electrode is deposited and dissolved, and the state of charge state progresses while the battery is being charged. Accordingly, a rectangular waveform charging / discharging current pulse is applied at an arbitrary timing, and a rising slope dV ₁ / dt and a falling slope dV ₂ / dt of the battery voltage waveform at the time of applying the charging / discharging current pulse are measured, obtains a value of at each time point measured at an arbitrary timing of _{the, d V 1 / dt, dV} 2 / dt or _{(dV 1 / dt) / (} dV 2 / dt), the maximum value of dV ₁ / dt is Value, dV ₂ / dt value is the minimum value, or (dV ₁ / dt) / (dV ₂ / dt) is the maximum value, and the point of charge state is the full charge point of the secondary battery It is characterized by determining.
[0007]
The secondary battery deterioration degree determination method of the present invention is a secondary battery deterioration degree determination method in which the active material of the electrode is deposited and dissolved. The ratio (Ah ₁ / Ah ₂ ) of the capacity (Ah ₁ ) of the fully charged point measured by the method for determining the full charge of the next battery and the capacity (Ah ₂ ) of the actually measured or rated full charge point when the battery is new. ) is characterized in that the degree of degradation of those said measured battery against the capacity of the fully charged the measured or rated when the battery is new (Ah _2).
[0008]
Furthermore, the dischargeable capacity determination method of the secondary battery of the present invention is a method for determining the dischargeable capacity of a secondary battery of a type in which the active material of the electrode is deposited and dissolved, and from the full charge point for each discharge time rate. The dischargeable capacity table of the measurement target battery is measured in advance and registered as a dischargeable capacity table, and the dischargeable capacity table for the full charge point of the measurement target battery determined by the full charge determination method is used. The dischargeable capacity is estimated.
[0009]
Further, the method for determining the battery state in the assembled battery system of the present invention is a method for determining the battery state in the assembled battery system in which a secondary battery in which the active material of the electrode is deposited and dissolved is combined. By calculating the full charge, the degree of deterioration or the dischargeable capacity of each battery by the method described in claim 1, 2, or 3, and by grasping the battery status of the assembled battery system in advance, an appropriate battery is obtained. It is characterized in that the replacement time is determined quantitatively, and the optimum battery operation without overcharge and overdischarge is enabled.
[0010]
Furthermore, the battery full charge, deterioration, and discharge capacity determination device of the present invention converts a power unit that generates a positive and negative constant current rectangular pulse and an analog value of a rising / falling state of a battery voltage waveform into a digital value. The full charge determination part which calculates | requires a full charge point by the full charge determination method of the secondary battery of Claim 1 based on the signal processing part and the digitally converted data, The degradation degree determination method of the secondary battery of Claim 2 A determination unit comprising a deterioration degree determination unit for determining a deterioration degree by the method and a discharge capacity estimation unit for estimating a dischargeable capacity by a dischargeable capacity determination method for a secondary battery according to claim 3, and from the power unit to the determination unit A control unit that controls the entire system according to the process and outputs a drive signal, and a display unit that displays the determination results are provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described taking a lead secondary battery as an example.
[0012]
1. Determination Method of Full Charging Point The determination method of the present invention uses a circuit configuration shown in FIG. 1 to lead positive (charge direction) and negative (discharge direction) rectangular wave current pulses (1.5 C × 500 ms) with short wavelengths. The battery is applied to the secondary battery 25, and as shown in FIG. 2, the full charge judgment of the battery is performed by grasping the degree of the rising slope dV ₁ / dt and the falling slope dV ₂ / dt of the battery voltage waveform appearing at that time. Is.
When the pulse current is applied to the battery, (1) active material reaction on the electrode surface, (2) charge accumulation in the electric double layer on the electrode surface, and (3) side reactions such as generation of H ₂ and O ₂ Happens.
[0013]
3 and 4 show an outline of the electrode surface reaction in the undercharged state and the fully charged state.
As shown in FIG. 3, in the undercharged state, the active material PbSO ₄ that contributes to charging is largely deposited on the positive and negative electrode surfaces, so that the voltage rise is slow when a rectangular wave current in the charging direction is applied. is there. As the charging progresses, the active material PbSO ₄ that has contributed to the charging so far gradually decreases, and as shown in FIG. 4, in the fully charged state, the influence of the electric double layer component formed on the electrode surface instead It becomes noticeable, and the rise of the voltage when a positive rectangular wave current is applied becomes steep (dV ₁ / dt increases). In the overcharge region, new active material generation due to side reactions occurs on the electrode surface, so that the rise of the voltage waveform at the time of pulse application becomes gradual (dV ₁ / dt decreases). That is, as shown in FIG. 5, the rising slope (dV ₁ / dt) of the voltage waveform increases as charging progresses, and starts to decrease when the overcharge region is reached (peaks at the full charge point).
[0014]
On the other hand, the slope (dV ₂ / dt) of the fall of the voltage waveform caused by the application of a negative (discharge direction) current rectangular pulse releases the charge stored in the electric double layer as shown in FIGS. Is done. That is, as the charge proceeds, the amount of charge stored in the electric double layer formed on the electrode surface increases, and thus the amount of discharge charge increases (dV ₂ / dt decreases). In the overcharge region, the discharge charge amount decreases (dV ₂ / dt increases) due to the decrease in the electric double layer capacitance component due to the generation of H ₂ and O _{2 on} the electrode surface.
[0015]
Thus, in the full charge determination, the slope dV ₁ / dt of the rise of the voltage waveform that appears when a positive (charge direction) rectangular current pulse is applied is large, and the rise of the voltage waveform when a negative (discharge direction) rectangular current pulse is applied. The point at which the downward slope dV ₂ / dt becomes smaller, that is, the point at which (dV ₁ / dt) / (dV ₂ / dt) is maximized is the full charge point.
[0016]
2. On the other hand, when the deterioration progresses, PbSO _{4 that} is inactive with an insulator increases on the electrode surface. For this reason, the electric double layer capacity component due to the reduction of the reaction electrode area is reduced, and a peak is generated with a small charge capacity. FIG. 7 shows a (dV ₁ / dt) / (dV ₂ / dt) graph of a new battery and a deteriorated battery. Compared with a new battery, the (dV ₁ / dt) / (dV ₂ / dt) graph of a deteriorated battery shifts to the left, and a peak point appears at an early stage of the charging rate. Here, the capacity Ah _{2 at} which the initial charge of the new battery is fully charged is registered beforehand, and the ratio of the fully charged point capacity Ah _{1 of} the deteriorated battery measured this time [(Ah ₁ / Ah ₂ ) × 100%] Shows the degree of deterioration of the battery.
[0017]
3. Discharge capacity estimation method The dischargeable capacity of the fully charged battery varies depending on the discharge mode (for example, time rate). Here, by previously registering the dischargeable capacity for each mode from the full charge point, it is possible to estimate the discharge capacity when the full charge point is found. According to the experiment, regarding the sealed battery for EV, the dischargeable capacity from the full charge derived was about 0.94 for 3 hour rate discharge and about 0.96 for 5 hour rate discharge.
[0018]
【Example】
Examples of the present invention will be described below.
FIG. 1 shows the configuration of an embodiment of a test apparatus according to the present invention, in which 21 is an arbitrary waveform generator, 22 is a bipolar power supply that outputs a direct current of, for example, −100 A to +100 A, 23 is a shunt, 24 is a switch, Reference numeral 25 is a battery, and 26 is a recorder.
[0019]
In this embodiment, an arbitrary waveform generator 21 generates a positive (charge direction) and negative (discharge direction) current rectangular wave of 0.5 seconds, and then the battery current rating of 1. 5C.
[0020]
The rectangular wave produced by this method is applied to a sealed lead battery whose capacity has been measured in advance, from the fully discharged state to the overcharged state, increasing the charging rate at about 0.1 C. Apply, and measure the rise and fall of the voltage waveform that occurs.
[0021]
As an example, the rising slope dV ₁ / dt and falling slope dV ₂ / dt of the battery voltage waveform at the time of charging / discharging rectangular current pulse application in each charge state of the test battery are measured, and the ratio (dV _{When 1} / dt) / (dV ₂ / dt) is taken, as charging progresses, the ratio gradually increases and starts to decrease at a certain charging point.
[0022]
When this point is the full charge point and the discharge amount at the charge amount before and after this is plotted, as shown in FIG. 8, the discharge amount has been saturated in the overcharge region with this full charge point as a boundary. It can be seen that this point indicates a full charge point (after the full charge, the discharge amount does not increase any further no matter how much the charge rate is increased).
[0023]
Further, the discharge capacity estimated from the pre-registered chargeable capacity estimation table from the full charge coincided with the discharge capacity extracted from the actual capacity test result.
[0024]
In the above embodiment, the point of the charged state where the value of (dV ₁ / dt) / (dV ₂ / dt) shows the maximum value is determined as the full charge point of the secondary battery. during charging and discharging current pulse application T1, T2, T2 / T1 or dV ₁ / dt, determined the value of dV ₂ / dt, the point of their charge state that indicates whether the value is the maximum or minimum value of the It can also be determined that the secondary battery is fully charged.
[0025]
FIG. 9 is a block diagram showing an embodiment of the present invention, in which 14 is a power unit for generating positive and negative constant current rectangular pulses, 15 is an analog value that is the slope of the rise and fall of the battery voltage waveform, and is a digital value. A signal processing unit 16 for conversion is based on the digitally converted data, and a determination unit 17 for performing full charge, deterioration level determination, dischargeable capacity estimation and remaining capacity estimation, and 17 controls the overall system movement and outputs a drive signal. The output control unit and 18 are display units for displaying these determination results.
[0026]
In this embodiment, a constant current rectangular pulse is applied to the battery 4 via the AC-DC converter 1, the bipolar power supply 2, and the switch 3 configured by the power unit 14 to the battery 4 to be measured.
[0027]
An analog value is converted into a digital value by the signal conversion circuit 5 configured by the signal processing unit 15 with respect to the rising slope (dV ₁ / dt) and the falling slope (dV ₂ / dt) of the battery voltage waveform generated at that time. The data is processed by the arithmetic circuit 6 into data having a correlation with the full charge / deterioration determination.
[0028]
Based on the result processed by the arithmetic circuit 6, the full charge determination unit 9 configured by the determination unit 16 obtains the full charge point indicating the maximum value and the minimum value, and the deterioration degree determination unit 10 The full charge point data of the new battery is stored in the table 7 in advance, and compared with the full charge point of the previous battery to be measured, the deterioration degree is calculated. Further, in the discharge capacity estimation unit 11, a discharge capacity estimation coefficient that can estimate the discharge capacity from the full charge point is stored in the table 8, and the dischargeable capacity of the battery 4 is estimated.
[0029]
On the other hand, the control unit 17 controls the drive signal 13 from the sequence control circuit 12 to generate positive and negative constant current rectangular pulses, and also stops the charging operation from the charger 19 based on the full charge determination information.
[0030]
The display unit 18 displays the results of the rising and falling voltage waveforms, and the determination result of the full charge and the degree of deterioration, and the dischargeable capacity.
[0031]
With this method, it is possible to determine the full charge of the battery, the degree of deterioration, the estimation of the discharge capacity, and the degree of deterioration, which is a significant improvement over the old method.
[0032]
The present invention can be applied as follows.
1. Since the full charge point of various batteries can be quantitatively determined by the full charge determination method of the present invention, it is possible to charge with a single charger regardless of the type of battery and the deterioration state by incorporating it in the charger. It can be applied to applications for chargers.
[0033]
2. Since the deterioration degree determination method of the present invention can quantitatively determine the deterioration degree of the battery, it can be used as a battery deterioration diagnosis device for commercially available batteries such as for UPS and automobile starters. Furthermore, by adopting it in a large assembled battery system, it can be used for a system that extracts deteriorated batteries from a plurality of batteries.
[0034]
3. Since the discharge capacity can be estimated in advance by the discharge capacity estimation method of the present invention, it is possible to achieve a battery operation prediction system that can be optimally operated according to the battery usage status by being incorporated in an electric power storage system and an electric vehicle system. It can be used.
[0035]
4). In the battery capacity test, the battery capacity can be determined by determining full charge even if the battery is not completely discharged. Therefore, it is possible to provide a battery capacity test apparatus utilizing the fact that the measurement time can be greatly shortened.
[0036]
5). Since the optimum charging is possible, the battery can be applied to a charging device in which the life of the battery is significantly improved.
[0037]
【The invention's effect】
As described above, the present invention has the following effects.
(1) Since an optimal full charge point for a battery can be determined quantitatively according to the use state and deterioration state of the battery, an optimal charging system can be realized by incorporating the battery into a charging device.
(2) By adopting a system having a large number of assembled batteries, such as a power storage device and an electric vehicle battery system, it is possible to quickly detect a deteriorated battery and contribute to improving the reliability of the system.
(3) The battery life can be extended by the above.
(4) It is possible to optimize the battery replacement time such as an assembled battery system.
(5) Various types of batteries can be charged with a single charging device.
{Circle around (6)} Since the dischargeable capacity can be known in advance without actually discharging, the capacity test, which has taken a long time, can be speeded up.
[Brief description of the drawings]
FIG. 1 is a test configuration diagram of a full charge determination and deterioration determination evaluation method using a rectangular pulse wave using a bipolar power source.
[Fig. 2] 1.5C, 0.5 second negative (discharge direction) constant current rectangular pulse applied to the measurement target battery, as well as 1.5C, 0.5 second positive (charge direction) constant current rectangular pulse It is a conceptual diagram which shows the measurement result of the voltage change (dV / dt) at the time of doing.
FIG. 3 is a diagram showing a state of a battery electrode surface reaction when a rectangular pulse wave is applied (charge, discharge) to an undercharged battery.
FIG. 4 is a diagram showing a state of a battery electrode surface reaction when a rectangular pulse wave is applied (charge, discharge) to a fully charged battery.
FIG. 5 shows the relationship between the time change of the rising and falling slopes of a battery voltage waveform when a rectangular current pulse wave is applied to a new battery (charging and discharging), the full charge point of the battery and the degree of deterioration of the battery as seen from the graph. FIG.
FIG. 6 shows the relationship between the time change of the rising and falling slopes of a battery voltage waveform when a rectangular current pulse wave is applied to a deteriorated battery (charging and discharging), the full charge point of the battery and the degree of deterioration of the battery as seen from the graph. FIG.
FIG. 7 is a diagram illustrating a ratio of rising (dV ₁ / dt) and falling (dV ₂ / dt) voltage waveforms of a new battery and a deteriorated battery when the charging rate is increased.
FIG. 8 is a diagram showing the transition of the discharge amount in the charge amount before and after the full charge point.
FIG. 9 is a block diagram of a full charge, deterioration degree and dischargeable capacity determination device.
[Explanation of symbols]
1 AC-DC converter, 2 bipolar power supply, 3 switch, 4 measurement battery, 5 signal conversion circuit, 6 arithmetic circuit, 7 deterioration degree determination table, 8 discharge capacity estimation coefficient, 9 full charge determination part, 10 deterioration degree determination part, DESCRIPTION OF SYMBOLS 11 Discharge capacity estimation part, 12 Sequence control circuit, 13 Drive signal, 14 Power part, 15 Signal processing part, 16 Judgment part, 17 Control part, 18 Display part, 19 Charger, 21 Arbitrary waveform generator, 22 Bipolar power supply, 23 shunts, 24 switches, 25
Battery, 26 recorder

Claims (5)

A method for determining the full charge of a secondary battery in which the active material of the electrode is deposited and dissolved,
While charging the battery, apply a rectangular wave charge / discharge current pulse at any timing according to the progress of the state of charge,
Measure the rising slope dV ₁ / dt and falling slope dV ₂ / dt of the battery voltage waveform when the charge / discharge current pulse is applied,
The value of dV ₁ / dt, dV ₂ / dt or (dV ₁ / dt) / (dV ₂ / dt) at each time point measured at the arbitrary timing is obtained, and the value of dV ₁ / dt is the maximum value. , DV ₂ / dt is the minimum value, or (dV ₁ / dt) / (dV ₂ / dt) is the maximum value, and the point of charge state is the full charge point of the secondary battery. A method for determining a full charge of a secondary battery, characterized by: A method for determining the degree of deterioration of a secondary battery in which the active material of the electrode is deposited and dissolved,
For the battery to be measured, the capacity (Ah ₁ ) of the full charge point measured by the method for determining the full charge of the secondary battery according to claim 1 and the capacity of the full charge point measured or rated when the battery is new ( characterized in that the Ah ₂₎ and the ratio (Ah ₁ / Ah ₂₎ the degree of deterioration of those said measured battery against the capacity of the fully charged the measured or rated when the battery is new (Ah ₂₎ A method for determining the deterioration level of a secondary battery A method for determining a dischargeable capacity of a secondary battery in which an active material of an electrode is deposited and dissolved,
The battery of the measurement object determined by measuring the dischargeable capacity from the full charge for each discharge time rate in advance and registering it as a dischargeable capacity table, and determined by the full charge determination method of the secondary battery according to claim 1 A method for determining a dischargeable capacity of a secondary battery, wherein the dischargeable capacity of the battery to be measured is estimated from the dischargeable capacity table with respect to a full charge point. A method for determining a battery state in an assembled battery system in which a secondary battery in which an active material of an electrode is deposited and dissolved is combined,
The full charge of each battery is determined by the secondary battery full charge determination method according to claim 1, the secondary battery deterioration degree determination method according to claim 2, and the secondary battery dischargeable capacity determination method according to claim 3. By calculating the degree of deterioration and dischargeable capacity, and knowing the battery status of the assembled battery system in advance, it is possible to quantitatively determine the appropriate battery replacement time, and optimal battery operation without overcharge and overdischarge A method for determining a battery state in an assembled battery system, characterized in that: The power unit for generating positive and negative constant current rectangular pulses, the signal processing unit for converting the analog value of the rising / falling state of the battery voltage waveform into a digital value, and the digitally converted data, according to claim 1. The full charge determination part which calculates | requires a full charge point with the full charge determination method of a secondary battery, the deterioration degree determination part which determines a deterioration degree with the deterioration degree determination method of the secondary battery of Claim 2, and the secondary of Claim 3 A determination unit including a discharge capacity estimation unit that estimates a dischargeable capacity by a battery dischargeable capacity determination method; and a control unit that controls the entire system from the power unit to the determination unit according to a process and outputs a drive signal; A battery full charge, deterioration, and discharge capacity determination device, characterized by comprising a display unit for displaying these determination results.

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