JP3385780B2 - Method for deriving regression equation for estimating capacity of Ni-Cd battery for trickle - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a trickle Ni-Cd.
The present invention relates to a method for deriving a capacity estimation regression equation for detecting a deterioration state of a battery by measuring an internal impedance and estimating a battery capacity.

[0002]

2. Description of the Related Art As a method of detecting the deterioration state of a Ni-Cd battery which is being used for trickle charging, a method of estimating the capacity from an internal impedance measurement is effective. This method focuses on the strong correlation between internal impedance and battery capacity. Therefore, in order to apply this method,
The relational expression between the internal impedance and the battery capacity (hereinafter,
It is necessary to obtain in advance). Therefore, in order to obtain this regression equation, conventionally, a characteristic test of a deteriorated battery actually used or a battery forcibly deteriorated by temperature acceleration or the like has been performed.

[0003]

However, the Ni-
Since deterioration of a Cd battery requires a long time, in order to obtain a deteriorated battery having a capacity of 50 to 60%, which is a criterion for battery life, deterioration due to actual use can take several years at the earliest, and even temperature-accelerated production can result in at least several months. Was required, and it took a long time to obtain the regression equation.

Therefore, in order to solve the above-mentioned problems of the conventional example, the present invention focuses on the fact that electrolyte dormancy is the predominant deterioration mode in Ni-Cd batteries using trickle, and the amount of electrolyte is below the standard. An object of the present invention is to provide a method for deriving a capacity estimation regression formula for a trickle Ni-Cd battery, which is used to obtain a regression formula in a short time from the characteristics of the pseudo-degraded battery manufactured as described above.

[0005]

In order to achieve the above-mentioned object, the present invention is directed to a Ni-for trickle from an internal impedance.
In a method for detecting the deterioration state of a Cd battery and estimating the battery capacity, a pseudo-deteriorated battery having a regression equation between the impedance and the battery capacity, which has the same standard as that of the battery but only the electrolyte amount is below the standard. It is characterized by being obtained from the characteristics of.

In the method of detecting the deterioration state of the trickle Ni-Cd battery or estimating the battery capacity from the internal impedance, the present invention uses a regression equation between the impedance and the battery capacity. It is characterized in that it is obtained from the characteristics of a pseudo-deteriorated battery that is manufactured with the standard capacity and size different from that of the battery and only the amount of electrolyte is below the standard.

Further, according to the present invention, the battery capacity is estimated from the real part Z _Re of the internal impedance in the method of detecting the deterioration state of the trickle Ni-Cd battery and estimating the battery capacity from the internal impedance. It is characterized by

Further, according to the present invention, in the method of detecting the deterioration state of the Ni-Cd battery for trickle and estimating the battery capacity from the internal impedance, the real part Z _Re of the internal impedance and the battery capacity Q are compared. It is characterized in that the regression equation between is in the form of Q = a × ln (Z _Re ) + b (a and b are arbitrary constants).

Further, the present invention is a method for detecting the deterioration state of a Ni-Cd battery for trickle and estimating the battery capacity from the internal impedance, in which the absolute value of the internal impedance | Z _Re + Z _Im | It is characterized by estimating the capacity.

Further, the present invention is a method for detecting the deterioration state of a Ni-Cd battery for trickle and estimating the battery capacity from the internal impedance, in the absolute value of internal impedance | Z _Re + Z _Im | It is characterized in that the regression equation with the capacitance Q is in the form of Q = a × ln | Z _Re + Z _Im | + b (a and b are arbitrary constants).

[0011]

By the above means, in the present invention, a pseudo-deteriorated battery whose amount of electrolyte is less than the standard is produced with respect to the standard Ni-Cd battery A for trickle, and the regression equation of this pseudo-degraded battery is Use regression equation. Further, in the case of a battery B manufactured by the same manufacturer whose nominal capacity and size are different from that of the battery A, if it can be regarded as “the same as the battery A in the design of the constituent materials such as electrodes and separators, their thickness, porosity, etc.” , The regression equation for battery B is derived from the regression equation for battery A.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows the amount of electrolyte and the battery capacity of a Ni-Cd battery [1] for a single type trickle [1] having a nominal voltage of 1.2 V and a nominal capacity of 4000 mAh manufactured by X company, which is used for the standard deterioration. It is a characteristic view which shows a relationship. The battery capacity was obtained by a test based on JIS. The standard value of the amount of electrolyte is 100%. In the graph, a decrease in battery capacity due to a decrease in electrolytic solution was observed, which shows pseudo deterioration characteristics. FIG. 2 is a characteristic diagram showing the relationship between the real part of the internal impedance of the battery R _{Im = 0} (here, the real part resistance at the frequency where the imaginary part becomes zero) and the battery capacity Q. The internal impedance was obtained by analyzing a frequency response analyzer with a galvanostat passing a current of 0.5 A. Linearity is observed in the graph, and the following equation is the regression equation for battery [1].

Q = -1095 × ln (R _{Im = 0} ) +6940 (1) Next, the effectiveness of the regression equation is verified by comparing it with the characteristics of a deteriorated battery that was actually used. Here, regarding the actual deteriorated battery of the battery [1], the Ni battery described above is used.
It has not been obtained so far because it takes a long time to produce a -Cd battery. Therefore, although the nominal capacity and the size are different, the verification is performed from the characteristics of the recovery battery manufactured by the same company X as the battery [1].

FIG. 3 is manufactured by Company X and has a nominal voltage of 1.2V.
Ni-C for single 2 type trickle with nominal capacity of 1800mAh
d Real part of internal impedance of battery [2] r _{Im = 0} (real part resistance at frequency where imaginary part becomes zero) and battery capacity q
It is a characteristic view which shows the relationship with. The battery capacity and internal impedance were determined by the same method as for battery [1]. Here again, the graph shows a good linear relationship, and the regression equation is as follows.

Q = −491 × ln (r _{Im = 0} ) +3233 (2) Comparing the equations (1) and (2), the equations are both Y = a × ln (X) + b (a , B are arbitrary constants) (3). Therefore, it can be considered that the regression equation when the electrolyte depletion is in the deterioration mode is always in the form of equation (3). Further, since the battery [1] and the battery [2] are trickle batteries manufactured by the same manufacturer, it can be considered that the constituent materials of the electrodes, the separators, etc., and their designs such as their thickness and porosity are the same. In this case, as shown in FIG. 4, the rate of decrease in battery capacity relative to the rate of increase in impedance from the undegraded state can be considered to be equal regardless of the nominal capacity and the battery size, and the regression equation of the battery [1] ( The regression equation of the battery [2] can be derived from the equation (1). First, if the battery capacity of the battery [1] in the undegraded state (electrolyte amount 100%) is Q _1, and the battery capacity and the impedance of the battery [2] in the undegraded state are q ₁ and r ₁ , respectively, The induction regression equation of the battery [2] is as follows. q ′ = − 1095 × (q ₁ / Q ₁ ) × ln (r _{Im = 0} / r ₁ ) + q ₁ (4) Here, Q ₁ is the average of the capacities when the amount of the electrolytic solution is 100% in FIG. 1. The value is set to 4962 mAh, and regarding q ₁ and r ₁ , since undegraded information is unknown, the average capacity 2383 mAh = q ₁ in the circle in FIG. 3 where the battery capacity is 2200 mAh or more, the same circle. The average impedance of the inside is 6.60 mΩ = r ₁ . From this, (4)
The formula looks like this:

Q ′ = − 526 × ln (r _{Im = 0} ) +3376 (5) The equation (5) is the induction regression equation of the battery [2]. In Figure 5,
The graph of Formula (2) and Formula (5) is shown. The two graphs are in good agreement, and in particular, the impedance corresponding to the capacity of 50 to 60%, which is the criterion for determining the battery life, has almost the same value, so that highly accurate life determination can be performed. From the above, the effectiveness of applying the regression formula of the pseudo-degraded battery to the actual deteriorated battery is shown, and the regression formula is also effective for the battery having a different nominal capacity or size from the pseudo-degraded battery. I knew that.

Further, when the relation between the real part of the impedance for each frequency or the absolute value of the impedance and the battery capacity is evaluated by using the correlation coefficient as an index, FIG. 6 and FIG. 7 results were obtained. In both graphs, a frequency range showing a high correlation with a correlation coefficient of 0.9 or more is observed. Therefore, it is understood that the battery capacity can be estimated with high accuracy by obtaining the real part of the impedance or the absolute value of the impedance in the frequency within this range and using the regression equation of the form (3).

[0018]

As described above, according to the present invention, the relational expression between the internal impedance and the battery capacity for an actually used battery can be obtained from the characteristics of the pseudo-deteriorated battery in which the amount of electrolyte is below the standard. You can The pseudo-deteriorated battery can be manufactured extremely easily and in a short time because only the amount of the electrolytic solution to be injected is changed with respect to the standard battery. Therefore, compared with the conventional method of collecting or producing the actual deteriorated battery, the operation is significantly reduced.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing the relationship between the amount of electrolyte and the battery capacity in a battery [1] of an example of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the real part of the internal impedance and the battery capacity in the battery [1] of the example of the present invention.

FIG. 3 is a characteristic diagram showing the relationship between the real part of the internal impedance and the battery capacity in the battery [2] of the example of the present invention.

FIG. 4 is a conceptual diagram showing a change in capacity with respect to a change in real part of internal impedance between batteries having different nominal capacities and battery sizes according to the present invention.

FIG. 5 is a graph of equations (2) and (5) according to an embodiment of the present invention.

FIG. 6 is a characteristic diagram showing the frequency dependence of the correlation coefficient between the real part of the internal impedance and the absolute value of the internal impedance and the battery capacity in the battery [1] of the example of the present invention.

FIG. 7 is a characteristic diagram showing the frequency dependence of the correlation coefficient between the real part of the internal impedance and the absolute value of the internal impedance and the battery capacity in the battery [2] of the example of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-37623 (JP, A) JP-A-5-281309 (JP, A) JP-A-5-281310 (JP, A) JP-A-8- 43506 (JP, A) JP-A-8-88028 (JP, A) JP-B 1-339068 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 10/42-10 / 48 G01R 31/36

Claims (6)

(57) [Claims] 1. Internal impedance to trickle Ni
In a method of detecting a deterioration state of a Cd battery or estimating a battery capacity, a pseudo-deterioration in which a regression equation between the impedance and the battery capacity is prepared with the same standard as that of the battery and only the amount of electrolyte solution is below the standard. A method for deriving a capacity estimation regression formula for a trickle Ni-Cd battery, which is obtained from battery characteristics. 2. Internal impedance to trickle Ni
In a method of detecting a deterioration state of a Cd battery or estimating a battery capacity, a regression equation between the impedance and the battery capacity is calculated so that only the amount of electrolyte solution is below a standard according to a standard having a different nominal capacity or size from the battery. A method for deriving a capacity estimation regression formula for a trickle Ni-Cd battery, which is obtained from the characteristics of the pseudo-degraded battery manufactured as described above. 3. Internal impedance to trickle Ni
-Cd In a method of detecting a deterioration state of a battery or estimating a battery capacity, the battery capacity is estimated from a real part Z _Re of the internal impedance, and the Ni-Cd for trickle according to claim 1 or 2, wherein Battery capacity estimation regression equation derivation method. 4. An internal impedance to trickle Ni
In the method of detecting the deterioration state of the Cd battery and estimating the battery capacity, the regression equation between the real part Z _Re of the internal impedance and the battery capacity Q is Q = a × ln (Z _Re ) + b ( The method for deriving a capacity estimation regression formula for a trickle Ni-Cd battery according to claim 3, wherein a and b are in the form of an arbitrary constant. 5. An internal impedance to trickle Ni
-Cd In the method of detecting the deterioration state of the battery and estimating the battery capacity, the absolute value of the internal impedance | Z _Re + Z _Im
The battery capacity is estimated from |, and the capacity estimation regression equation derivation method of the trickle Ni-Cd battery according to claim 1 or 2. 6. An internal impedance to trickle Ni
-Cd In the method of detecting the deterioration state of the battery and estimating the battery capacity, the absolute value of the internal impedance | Z _Re + Z _Im
6. The trickle Ni according to claim 5, wherein the regression equation between | and the battery capacity Q is in the form of Q = a × ln | Z _Re + Z _Im | + b (a and b are arbitrary constants). -Cd battery capacity estimation regression equation derivation method.