JP2001286064A - Capacity estimating method for lithium ion battery, method and apparatus for judging deterioration and lithium ion battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method for estimating the capacity of a lithium ion battery, a simple method and an apparatus for judging the deterioration of the lithium ion battery, and a lithium ion battery pack provided with a means which estimates the capacity of the battery and gives warning of the deterioration of the battery as occasion demands. SOLUTION: A capacity estimating method for a lithium ion battery finds a time interval (t) from the point of time when a charging voltage in the course of constant-current(CC) charging by a charging current Ic reaches a preset voltage Vs, up to the point of time when a charging condition is switched from the constant current(CC) charging over to constant voltage (CV) charging, when the lithium ion battery is charged by a constant-current constant-voltage system; and calculates an estimated capacity C of the lithium ion battery using the time internal (t). A method and an apparatus are provided for judging the deterioration of the lithium ion battery by the method. A lithium ion battery pack provided with a means for executing the capacity estimating method is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the capacity of a lithium ion battery, a method for determining deterioration, a device for determining deterioration, and a lithium ion battery pack.

[0002]

2. Description of the Related Art In recent years, demands for batteries have been increasing due to miniaturization, high performance, and portableness of various electronic devices. In response, battery improvements and developments are becoming more active. Also, new application areas of batteries are expanding.

[0003]

With the spread of batteries,
There is a growing demand for improved reliability of these mounted batteries. In particular, nickel-metal hydride batteries (hereinafter, referred to as Ni / MH batteries) having a significantly higher energy density per volume or weight than conventional lead batteries and nickel cadmium batteries (hereinafter, referred to as Ni / Cd batteries) and Lithium-ion batteries (hereinafter referred to as Li-ion batteries) have a large amount of energy stored inside, and the degree of damage caused by accidents caused by battery abnormalities can be even more severe, ensuring reliability. It is an important issue.

Also, lead batteries, Ni / Cd batteries, and N
While the i / MH battery has a reaction mechanism for absorbing gas generated by a side reaction due to overcharging, the Li-ion battery does not have an absorption reaction for gas generated by overcharging. There are big restrictions. Further, a plurality of L
When i-ion batteries are arranged in series and used, as the battery deteriorates, the imbalance of the individual battery characteristics causes overcharging or overdischarging, which can be a major concern in terms of safety.

[0005] As one of the reliability securing means, there is a method of accurately grasping the state of deterioration of the mounted battery and replacing the battery in a timely manner. Regarding high energy density batteries such as Ni / MH batteries and Li-ion batteries, the smart battery system (SBS) proposed in 1994 has become popular as a battery management system including charge control and remaining capacity determination, with improvements. (Www.sbs-fo
rum.org). These battery controls / managements include information such as the manufacturer and battery type, as well as the battery current, voltage,
Only a method based on enormous information data management for monitoring temperature and the like is employed, and such a method is an extremely expensive method and has resulted in a rise in product prices.

As for the monitoring of the state of deterioration of the battery, which is important in maintaining safety, the use of a Li-ion battery-equipped device is frequently changed, so that the usage time is secured and monitored. They tend to be neglected as much as possible.

[0007] In particular, SBS is a means for controlling and managing the charge and remaining capacity of the battery, and has no function of grasping the state of deterioration of the battery. It was the present situation that relied on intuition.

[0008] Apart from SBS, a control / management method of a Li-ion battery mounted on a video camera has been proposed. In this method, the deterioration of the battery is determined from the display of the measured capacity. That is, it is not always possible to correctly determine whether or not a battery used after charging has deteriorated.

The present invention has been made in view of the above points, and has as its object a simple method for estimating the capacity of a Li-ion battery, a simple method and an apparatus for determining deterioration of a Li-ion battery, and a battery. It is an object of the present invention to provide a Li-ion battery pack provided with a means for estimating the capacity of a battery and warning the battery of deterioration as necessary.

[0010]

According to the present invention, there is provided a method for estimating the capacity of a lithium ion battery, comprising the steps of: When charging by the voltage method,
The charging voltage during constant-current charging is a predetermined voltage V
a time t from a point in time at which the charging condition is reached to a point in time when the charging condition is switched from a constant current to a constant voltage, and the estimated capacity C of the lithium ion battery is calculated using the time t. Of the capacity estimation method.

[0011] In the present invention, as described in claim 2, in a volume estimation method of a lithium ion battery according to claim 1, the constant when the nominal capacity of the lithium ion battery and C ₀ The charging current during current charging is C
The time t is determined as ₀ / (30 hours) or more and C ₀ / (1 hour) or less, and the estimated capacity C of the lithium ion battery is expressed by a relational expression using the time t, C / C ₀ = A × t ^B. (1) (where A and B are the lithium ion battery and the voltage V
s and a positive constant determined by the charging current during the constant current charging).

Further, in the present invention, as described in claim 3, a lithium ion battery whose capacity is to be estimated or a lithium ion battery of the same type as the lithium ion battery is used, and one full charging time is used. Two charge / discharge cycles including a charge period by a constant current / constant voltage method of 3 hours or more and 10 days or less, a discharge period, and, if necessary, a pause period provided between the charge period and the discharge period. By repeating the above, in each cycle, the time t _n (where n is the time from when the charging voltage during the constant current charging reaches the preset voltage Vs to when the charging condition is switched from the constant current to the constant voltage). And the discharge capacity C _n obtained by integrating the discharge current with respect to time for each cycle, and the recorded time t _n and the discharge capacity are recorded. From the amount C _n, forming the capacitor estimation method of a lithium ion battery according to claim 2, wherein the determining A, the value of B in the above equation (1).

According to a fourth aspect of the present invention, there is provided a method for judging deterioration of a lithium ion battery, wherein the estimated specific capacity C of the lithium ion battery is determined according to the first, second or third aspect. A lithium ion battery calculated by a method for estimating the capacity of a lithium ion battery, and determining that the lithium ion battery has deteriorated when the estimated capacity C is smaller than a preset limit capacity C _min. The method for judging the deterioration of is described.

According to a fifth aspect of the present invention, there is provided an apparatus for judging deterioration of a lithium ion battery, wherein the lithium ion battery is charged by a constant current constant voltage method during constant current charging. Means for measuring a time t from a point in time when the charging voltage reaches a preset voltage Vs to a point in time when the charging condition is switched from constant current to constant voltage, and using the time t, An arithmetic circuit for calculating the estimated capacity C of the lithium-ion battery by the method for estimating the capacity of the lithium-ion battery described in 3, and the estimated capacity C calculated by the arithmetic circuit is smaller than a preset limit capacity C _min. Means for outputting a signal indicating the deterioration of the lithium ion battery when the condition is satisfied. To achieve.

According to the present invention, there is provided a lithium ion battery pack provided with a charge / discharge control means having a built-in IC.
C is a memory for storing a numerical value used for calculating the estimated capacity C of the lithium ion battery in the lithium ion battery pack, and an additional IC when the numerical value is stored in the memory. An arithmetic circuit for calculating the estimated capacity C by the method for estimating the capacity of a lithium ion battery according to claim 1, 2, or 3 from the time t and the numerical value when the ion battery is charged by the constant current and constant voltage method. A lithium ion battery pack characterized in that it has a lithium ion battery pack.

Further, in the present invention, the estimated capacity C of the lithium ion battery in the lithium ion battery pack calculated by the arithmetic circuit is set in advance in the lithium ion battery. 7. The lithium ion battery pack according to claim 6, further comprising means for outputting a warning indicating capacity deterioration when the capacity becomes smaller than the set limit capacity C _min .

In the present invention, the warning is a warning by an electric signal, a warning by displaying characters or images, a warning by a signal sound, or a warning by sound. A lithium ion battery pack according to claim 7 is constituted.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for estimating the capacity of a Li-ion battery according to the present invention will be described in more detail with reference to the drawings. In the following description, a "battery pack" refers to a unit cell or a plurality of unit cells connected in series, connected in parallel, or a combination of both, integrated with a safety control circuit or charge / discharge control circuit. It means what is referred to as a "secondary battery as an independent power source".

FIG. 1 is a diagram showing changes over time in battery voltage and current value during charging of a Li-ion battery. In FIG. 1, the battery or a Li-ion battery in the battery pack (hereinafter, these are collectively referred to as a Li-ion battery) is first set to a predetermined constant current I by a constant current (CC) mode.
c, a preset upper limit voltage Vc (normally 4.c).
1 V / cell, or 4.2 V / cell, where
After the charging voltage reaches the set voltage Vc, charging in the constant voltage (CV) mode is started, and the charging voltage (indicated as a battery voltage in FIG. 1). The charge current value attenuates with time while Vc remains constant at Vc.

In the method for estimating the capacity of a Li-ion battery according to the present invention, in the constant-current constant-voltage (CC-CV) method of charging, during charging in the constant-current (CC) mode, the charge upper limit is set at a discharge end voltage Vd or higher. The elapsed time t from when the battery voltage reaches an arbitrary voltage Vs set in advance so as to be lower than the voltage Vc to when the constant current mode charging is switched to the constant voltage mode is monitored. Used for estimating the capacity of the Li-ion battery.

The reason why such estimation is possible will be described below.

In the charging process of the Li-ion battery, Li in the positive electrode becomes positive ions and moves in the electrolyte to enter the negative electrode. In the discharging process, on the contrary, Li in the negative electrode becomes positive ions. As it moves, it moves in the electrolyte and enters the positive electrode.

The repetition of charge / discharge, long-term rest, or overcharge causes Co, N
The i-compound is eluted into the electrolyte, Li and the electrolyte are chemically decomposed and decomposed on the negative electrode surface to form an inert film,
L no longer reacts with the Li reactant or electrode reaction in the electrode
i remains or the bonding of the particles of the electrode constituent material deteriorates, so that the movement of electrons and ions is not performed smoothly. As a result, the capacity of the battery decreases, and at the same time, the internal resistance of the battery increases, and the rate at which Li ions are separated from the positive electrode during charging and reach the negative electrode, and diffuse into the negative electrode, decreases. In such a state, the charging time in the constant current (CC) mode becomes shorter because the internal resistance of the battery is increased, and in the constant voltage (CV) mode charging, the diffusion of Li in the negative electrode becomes slower. , The decrease of the current value is delayed.

The present inventors have found a remarkable correlation between the reduction in the capacity and the reduction in the charging time in the constant current (CC) mode, which has led to the present invention.

Hereinafter, embodiments of the present invention will be specifically described. (Embodiment 1) First, an embodiment of the invention according to claim 1 will be described. In the present embodiment, when charging the lithium ion battery by the constant current / constant voltage method, the charging condition is changed from the constant current to the constant voltage when the charging voltage during the constant current charging reaches the voltage Vs set in advance. Is calculated, and the estimated capacity C of the lithium ion battery is calculated using the time t.

In order to make such estimation possible, it is necessary to previously obtain the correlation between the estimated capacity C and the time t. For example, the following method is used. There is. That is, a lithium ion battery having the same structure and the same specifications as the lithium ion battery whose capacity is to be estimated (hereinafter referred to as the same type) is prepared, and the charge / discharge cycle is repeated using the battery. and the time t _n in each cycle, the discharge current is obtained in advance the correlation between the discharge capacity C _n of the battery obtained by integrating with respect to time (here, n represents a number assigned to each cycle). In this case, since it is desirable that over the value a wide range of discharge capacity C _n, in which case the range is narrow, as for a plurality of lithium ion batteries with different capacities in the same type, to perform the above method It is hopeful.

The above correlation need not necessarily be represented by an analytical mathematical formula, but may be represented, for example, by a broken line connecting measurement points in a correlation diagram with a straight line.

As in the case of the second embodiment described below, when the correlation expressed by an analytic formula is adopted as the above-described correlation, the charging current Ic during the constant-current charging is used. There is a preferred range.

It should be noted that the value of the estimated capacity C of the battery calculated at the time of each charge is recorded, and a relationship between the estimated capacity C and the number of times of charging is obtained. The lifetime, that is, how many recharges / reuses are possible before deterioration can be predicted. If the lithium ion battery is repeatedly used under the same or similar use conditions and is repeatedly charged and discharged, the life expectancy becomes highly accurate. (Embodiment 2) Next, an embodiment of the invention according to claim 2 will be described. In the present embodiment, the charging current Ic during the constant current charging in the first embodiment is limited, and the other points are the same as in the first embodiment. Restrictions on the charging current Ic, the nominal capacity of the lithium ion battery to be subjected to capacity estimated as _{C 0,} denoted as _{C 0} / (30 _{hours) ≦ Ic ≦ C 0 / (} 1 hour). This condition is set to 0.
It is expressed as 033 CmA or more and 1.0 CmA or less.

If the charging current Ic satisfies the above condition,
The above relational expression, that is, C / C ₀ = A × t ^B (1) (where A and B are the lithium ion battery and the voltage V
(a positive value constant determined by s and the charging current Ic) approximately holds, so that the estimated capacity C can be calculated using the time t by this relational expression.

When the charging current Ic does not satisfy the above condition, it is not preferable to calculate the estimated capacity C by the relational expression (1). That is, when the charging current Ic is smaller than the above-mentioned limit range, the charging is not performed sufficiently, the influence of the self-discharge cannot be ignored, or the capacity calculated by the relational expression (1) differs from the actual capacity. Would. If the charging current Ic is larger than the above-mentioned limit range, the required charging time itself is short, and a large error may occur in the measured value of the time t, or the change in the charging time due to deterioration may be different. It is difficult to accurately estimate the capacity.

However, since the charging current value applied to almost all the devices and chargers equipped with a Li-ion battery is within the above-mentioned condition range, for a Li-ion battery used under normal conditions, The capacity estimation method according to the present embodiment is effective.

Devices and chargers that employ current values in other ranges are used only for very specific applications, such as when a special application is required, for example, when ultra-rapid charging is required for use in an emergency. And a device and a charger that hardly require the capacity estimation method of the present invention.

The above-mentioned relational expression (1) shows that Li
It is assumed that the above time t of the constant current (CC) mode during charging in the charging condition of the mounting device or charger ion batteries, the relationship between the estimated specific capacity C / C ₀ in its conditions. If the relational expression (1) is created, C
When the charging current value in the C mode is different from the charging current value in the CC mode of the battery-equipped device or the charger, the time t is separately obtained in advance under each charging condition, and the relational expression (1) is created. The time t under the condition of time
The value obtained by multiplying the actually measured time by the ratio te / tm of e and the time tm under the conditions corresponding to the mounting device or the charger is substituted into the above-mentioned relational expression (1).

This is because the charging rate in the CC mode charging (the charging rate of the CC mode charging during the entire charging period) increases as the current value decreases, and therefore, the charging achievement rate increases as the current value decreases. In addition, since the ratio varies depending on the battery size, battery shape, manufacturer, battery constituent material, and the like, it is necessary to separately perform an actual test to grasp the influence of the current value.

In order to create the relational expression (1), the values of the constants A and B in the relational expression (1) must be determined. For this purpose, for example, as described in the first embodiment, it is most appropriate to determine the values of the constants A and B using the same type of battery or battery pack as the Li-ion battery whose capacity is to be estimated. is there. This is because commercially available Li-ion batteries use a variety of positive electrode active materials, negative electrode carbons, and electrolytes, and not only change in charging voltage behavior due to battery deterioration, but also initial charging behavior of batteries. Because it is.

The method of determining the values of the constants A and B will be described in detail in the following description of the third embodiment. (Embodiment 3) Next, an embodiment of the invention according to claim 3 will be described. In the present embodiment, using a lithium ion battery or a lithium ion battery of the same type as the lithium ion battery whose capacity is to be estimated,
A charging period based on a constant current / constant voltage method in which one full charging time is 3 hours or more and 10 days or less, a discharging period, and a pause period provided between the charging period and the discharging period as necessary. The charging / discharging cycle is repeated twice or more, and in each cycle, the time t from the point when the charging voltage during the constant current charging reaches the voltage Vs set in advance to the point when the charging condition is switched from the constant current to the constant voltage. _n (where n is a number assigned to each cycle) and a discharge capacity C _n obtained by integrating the discharge current with respect to time for each cycle, and the recorded time t _n and the time t _n are recorded. and a discharge capacity C _n, to confirm the value of a, B in the above equation (1), using these values, by the same method as in the first or second embodiment, to calculate the estimated capacity.

A more specific method of determining the values of A and B will be described below.

Using the same type of battery or battery pack for which deterioration is to be determined, and setting the environmental temperature between 10 ° C. and 30 ° C.
And -10 ° C or more and 5 ° C or less, and two kinds of charge / discharge cycle tests set so that the difference between the respective set temperatures is 15 ° C or more. What you get.

The test was performed at 10 ° C. or more and 30 ° C. or less, and −1
The reason that the temperature is set separately between two temperatures of 0 ° C. or more and 5 ° C. or less, and the difference between the set temperatures is set to be 15 ° C. or more is that the Li-ion battery is actually mounted,
The characteristics at the environmental temperature at which the deterioration is judged or at a temperature very close to the temperature are reflected in the relational expression (1) to ensure high accuracy, and the battery is tested at a low temperature of 15 ° C. or more. This is for obtaining battery characteristic data at an extremely low capacity similar to the case where the deterioration of the battery has greatly advanced. If the environment is 10 ° C or higher, or close to the environment 3
A test under only one type of temperature of 0 ° C. or lower requires an enormous amount of time until the battery deteriorates, which is not preferable.

In the charge / discharge cycle test for preparing the relational expression (1), a voltage range under the same conditions as the upper limit charging voltage Vc and the end-of-discharge voltage Vd of the mounted device is set. This is performed by setting the same or an arbitrary charging current value of 0.033 CmA or more and 1.0 CmA or less.

The charge time per cycle is set to 3 hours to 10 days, preferably 3 days to 10 days in a test in which the test environment temperature is set to 10 ° C. to 30 ° C. By setting the charging time per cycle to 3 hours or more and 10 days or less, preferably 3 days or more and 10 days or less, the deterioration of the battery in each cycle proceeds appropriately,
It is possible to efficiently obtain data necessary for creating the highly accurate relational expression (1).

When the charging time is less than 3 hours, the progress of deterioration of the Li-ion battery is slow, and several hundred cycles are required to acquire data for creating the highly accurate relational expression (1), and a huge amount of time is wasted. In some cases, charging may be insufficient, and deterioration and poor charging may be mixed, making it impossible to correctly determine deterioration and characteristics, which are both undesirable.

The charging time per cycle is 10
If the setting is made longer than the day, the elapsed time per cycle becomes longer, and it takes time to acquire data, which is similarly unfavorable.

On the other hand, when the test environment temperature is set at -10 ° C. or more and 5 ° C. or less, the charging time per cycle is shorter than that at the above-mentioned test at 10 ° C. or more and 30 ° C. or less, preferably 3 hours or more and 24 hours or less. Is set to 3 hours or more and 12 hours or less. The reason is that, in the case of charging and discharging at a low temperature, unlike the charging and discharging near room temperature, the degree of battery deterioration due to overcharging in charging within a set voltage range is reduced. Therefore, in the case of the low-temperature test, the deterioration of the battery is promoted by increasing the number of charge / discharge cycles within a certain test period. If the upper limit of the charging time is 12 hours, the effect is further increased.

If the charging time is longer than 24 hours (1 day), the number of cycles is reduced, and the battery is not deteriorated. On the other hand, if the charging time is less than 3 hours, the battery is insufficiently charged, and the deterioration of the battery is not promoted.

The discharge current value in the above charge / discharge cycle test is set to 0.5 CmA or more and 2.0 CmA or less. If the lower limit current is set to 1.0 CmA or more and 2.0 CmA or less, more efficient data acquisition becomes possible. 0.5Cm
In the case of a low discharge current of less than A, complete discharge takes a long time, which is not preferable. Further, when the discharge current is greater than 2.0 CmA, the discharge time itself becomes too short, and when the measured value of the discharge capacity fluctuates or when the deterioration progresses, the capacity sharply decreases and the relational expression (1) with high accuracy is obtained. It is not preferable because it becomes impossible to create

In carrying out the above-described charge / discharge cycle test, a pause for a fixed time is set between charging and discharging, if necessary, due to restrictions on the setting of the apparatus.

In the charge / discharge cycle test performed to create the above relational expression (1),
And time t _n from any voltage Vs to CC mode charging is terminated in the operating voltage range is smaller than the charging upper limit voltage Vc at the discharge end voltage Vd or at a constant current (CC) mode charging of, subsequent discharge discharge capacity C _{n (determined} by integration with respect to the discharge current time) and measured for each KakuTakashi discharge cycle upon (here, n represents a number assigned to each cycle). The measured time t _n and the capacitance C _n are plotted and applied to the relational expression (1) to determine the constants A and B.

The charge / discharge cycle test is performed for two or more cycles in order to satisfy the data of the time t and the capacity C required to make the deterioration judgment result highly accurate within ± 20% of the actual capacity. If there is only one cycle, only two data points can be used for the determination of the constants A and B in the relational expression (1). (Embodiment 4) Next, an embodiment of the invention according to claim 4 will be described.

The estimated capacity C of the Li-ion battery is calculated by the method in the first, second, or third embodiment, and the estimated capacity C is replaced with a predetermined limit capacity C.
_min , when C <C _min , the L
It is determined that the i-ion battery has deteriorated. However, this comparison is equivalent to the estimated specific capacity C / C ₀ (where C ₀
Is a nominal capacity) and the critical specific capacity C _min / C ₀ . For example, in Embodiments 2 and 3, C / C ₀ is directly calculated by the relational expression (1), so this comparison is more convenient.

As the limit capacity C _min , for example, a value of 60% of the nominal capacity C ₀ is used (in this case, C
_min / C ₀ = 0.6). (Embodiment 5) Next, an embodiment of the invention according to claim 5 will be described.

The entire apparatus capable of executing the deterioration judgment method in the fourth embodiment constitutes the present embodiment. For example, when charging a lithium-ion battery by the constant current / constant voltage method, from the time when the charging voltage during constant current charging reaches a preset voltage Vs to the time when the charging condition is switched from constant current to constant voltage. Means for measuring the time t, an arithmetic circuit for calculating the estimated capacity C of the lithium ion battery by the method for estimating the capacity of the lithium ion battery according to claim 1, 2 or 3, using the time t; The estimated capacity C (or estimated specific capacity C / C ₀ ) calculated by the circuit is set to a preset limit capacity C
_The present embodiment is an apparatus including means for outputting a signal indicating that the lithium ion battery is deteriorated when it becomes smaller than _min (or the critical specific capacity C _min / C ₀ ).

FIG. 2 shows a more specific embodiment of the present invention.

FIG. 2 is a diagram showing one configuration concept around a general power supply section of a device in which a Li-ion battery is mounted.
Reference numeral 1 denotes a power supply unit.
a, 2b, 2c, and these batteries 2a, 2b,
2c is controlled by the battery control unit 3 in the power supply unit 1 for charging / discharging and safety. Reference numeral 4 denotes a charger in the power supply unit 1, which charges the batteries 2a, 2b, 2c under the control of the battery control unit 3. Reference numeral 5 denotes a logic unit. The logic unit 5 includes an interface 6, a CPU 7, a memory 8, and a keyboard controller 9. The battery control unit 3 is connected to the CPU 7 via the interface 6 and relates to the mounted batteries 2 a, 2 b, and 2 c. Upon receiving the information and the instruction to execute the control, on the other hand, it transmits data relating to the battery control to the CPU 7. In the logic unit 5, the CPU 7 and the memory 8 perform control instructions, data calculations, storage of information related to battery control, data storage, and the like. The ID input of the batteries 2a, 2b, 2c and the like are performed via the keyboard controller 9. Wiring 10 for data transmission is connected to the keyboard controller 9.

The relational expression (1) in the present invention is input in advance to an empty memory or the like of the CPU 7, or is input by adding a memory chip in addition to the CPU 7 if necessary. The CPU 7 supplies a constant current (CC) to the battery control unit 3.
An instruction is performed to measure the time t from when the charging voltage in the mode charging reaches the voltage Vs within the working voltage range to when the CC mode charging is switched to the CV mode charging. Receive the data.
Further, the CPU 7 calculates the received time t by the relational expression (1).
To calculate the value of the estimated capacity C (or the estimated specific capacity C / C ₀ ). If necessary, the value of the estimated capacity C (or the estimated specific capacity C / C ₀ ) is stored in the memory 8. This estimated capacity C (or estimated specific capacity C / C ₀ )
Is compared with a preset limit capacity C _min (or limit specific capacity C _min / C ₀ ), and C <C
_min (or C / C ₀ <C _min / C ₀ ), it is determined that the Li-ion battery has deteriorated. Deterioration judgment results can be obtained by appropriate wiring 1 such as a system management bus.
0 is input to the apparatus main body. The apparatus main body displays the deterioration determination result on the display unit of the apparatus main body in accordance with the input, and issues a warning by a signal sound or a sound as necessary. In this way, an apparatus having the function of determining deterioration of the Li-ion battery according to the present invention can be configured. However, the configuration is not limited to the above configuration as long as the deterioration determination of the Li ion battery according to the above concept can be performed. (Embodiment 6) Next, an embodiment of the invention according to claim 6, 7, or 8 will be described.

An example of the present embodiment will be described with reference to FIG. FIG. 3 is a diagram showing a general circuit configuration of a Li-ion battery pack, in which Li-ion batteries (12-1, 12-2,
12-3) shows a case where three cells are mounted in series.

In FIG. 3, reference numeral 11 denotes a battery pack body, and reference numerals 12-1, 12-2, and 12-3 denote Li-ion batteries. A protection IC 13 monitors voltage, current, temperature, and the like, and performs software-based safety control. 14-A, 14-
B, 14-C, 14-1, 14-2, and 14-3 are FEs for the purpose of controlling the charging current of the inside of the pack body 11 and each battery.
T is a PTC element which is a thermal fuse;
Is a current fuse, which has a role of interrupting the current at the time of temperature rise and abnormally large current, respectively. 17 is a plus terminal,
Reference numeral 18 denotes a negative terminal, and 19 denotes a terminal for information output and control.

In FIG. 3, a protection IC for the above-mentioned safety mechanism is provided.
13 is equipped with a timer, the above-mentioned relational expression (1) is input in advance to an empty memory, and the voltage between both ends of the Li-ion batteries 12-1, 12-2, 12-3 in FIG. With this, the protection IC 13 monitors,
The charging voltage in the constant current (CC) mode charging of charging is
The elapsed time t from reaching an arbitrary start voltage Vs preset to be lower than the charge upper limit voltage Vc at the discharge end voltage Vd or higher and lower than the charge upper limit voltage Vc until the CC mode charge is switched to the CV mode charge is counted. The value of the measured time t is substituted into the relational expression (1) and calculated to calculate the estimated capacity C.
Is calculated. If necessary, an additional IC can be provided at an appropriate position in the pack separately from the protection IC 13. When it becomes smaller than the calculated estimated capacity C (or estimated specific capacity C / C ₀₎ is preset limit capacity C _{mi n (or} limit specific capacity C _min / C _0), it means the capacity deterioration Warning (in this case, warning by electric signal)
Is output to an apparatus main body equipped with a pack in order to display and emit the same through a terminal 19 on an appropriate display or a warning sound.

In the case where the device main body on which the Li-ion battery pack is mounted is not provided with a means for warning of deterioration, the pack itself issues this warning, for example, by displaying characters or images, signal sounds or voices. It is convenient to have a means for outputting by means of the following. Such a Li-ion battery pack can be manufactured by using the present invention and the conventional technique together.

As described above, it is possible to provide a Li-ion battery pack provided with a means for executing the deterioration determination method according to the present invention by making a minimal change to the existing Li-ion battery pack. However, the configuration is not limited to the above configuration as long as the deterioration determination of the Li ion battery according to the concept can be performed.

As a method for judging the deterioration of the Li-ion battery of the present invention and the object to which the Li-ion battery having the function of judging the deterioration is applied, a device which particularly requires high reliability can be considered. By grasping the state of deterioration of the battery and realizing timely replacement of the battery, troubles in the device can be avoided. However, as long as the device is equipped with a Li-ion battery, there is no problem in adopting the above-described method of determining deterioration and adopting a Li-ion battery having a function of determining deterioration, and it is possible to realize battery replacement without waste. The advantage of using it is very large.

[0063]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for estimating the capacity of a Li-ion battery, a method for judging deterioration and a device for judging deterioration of a Li-ion battery according to the present invention will be described.
The i-ion battery pack will be described more specifically with reference to examples, but the present invention is not limited to these examples. (Example 1) Prismatic Li-ion battery (600 mA nominal capacity)
About h), the test temperature was set to 25 ° C. and 0 ° C. using an automatic battery charge / discharge tester having a data collection / storage function.
, Charging current value 600 mA (charging current rate 1.0 C, 1.0 CmA), charging upper limit voltage 4.1 V, 25
C. A constant temperature constant voltage (CC-CV) method of charging for 7 days at a test temperature of 0 ° C. and 3 hours at a test temperature of 0 ° C., and a discharge current value of 600 mAh (discharge current rate of 1.0)
C, 1.0 CmA), discharge at a discharge end voltage of 2.75 V,
1 hour sandwiched charge-discharge cycle test pause performed 5 cycles between charging and discharging, and the elapsed time t until the CC mode charge completion from the time of start of charging in each cycle, the ratio nominal capacitance capacitor C _n / C ₀ (where n is a number assigned to each cycle) was measured (in this case, the voltage Vs was assumed to be equal to the charging voltage at the start of CC mode charging).

FIG. 4 shows the obtained data. FIG. 4 is a diagram showing the relationship between the elapsed time t and the specific capacity C _n / C ₀ showing the results of the charge / discharge cycle test, _where 4-A is 25 ° C.
, 4-B is the result population at 0 ° C. From these data, the constants A and B of the functional relational expression (1) of the time t representing the estimated specific capacity C / C ₀ are obtained,
The following relational expression (2) was created.

C / C ₀ = 1.067 × t ^0.228 (2) In the above equation (2), t is strictly t / (1 hour), that is, t is dimensionless in units of time. It must be represented by a number, which is simply represented by t for convenience. The same applies to the following equations.

The relation represented by the above-mentioned relational expression (2) is expressed by the 4-
C.

Separately, a prismatic Li-ion battery (nominal capacity: 600 mAh) of the same type was prepared, and a charging current of 600 m
A (1.0 CmA), charge upper limit voltage 4.1 V, charge time 3
Time constant current constant voltage (CC-CV) charging,
Discharge current 600 mA / 1.0 CmA), discharge end voltage 2.
75V discharge and charge / discharge cycles with a 10-minute pause between charge / discharge are performed.
The required time t (hr) for the C-mode charging and the nominal capacity 600
The ratio of the discharge capacity _{C n} for mAh, i.e. specific capacity _{C n}
/ C ₀ was recorded, and the validity of the relational expression (2) shown above was examined.

FIG. 5 shows the results. FIG. 5 shows the required time t for CC mode charging and the specific capacity C determined in the above charging / discharging cycle.
FIG. 11 is a diagram showing a relationship with _n / C ₀ , in which data up to the eleventh cycle is plotted. FIG. 5 also shows FIG.
The curve showing the relationship represented by the relational expression (2) obtained by
In A, a curve showing a value 20% higher than the value of the relational expression (that is, error + 20%) is represented by 5-B, and a curve showing a value 20% lower than the value of the relational expression (error -20%) is represented by 5-B. Also shown with -C.

As shown in FIG. 5, all data have an error of ±
It falls within 20%, and the curve 5-A of the relational expression (2)
Is very close to the data point, and excellent
It can be seen that the result is shown. (Example 2) Prismatic Li-ion battery (nominal capacity 600 mA
h) Battery charging / discharging with data collection / storage function
The relational expression of Example 1 was created by the electronic automatic testing device.
A charge / discharge cycle test under the same conditions as
CC mode charging from the start of charging in each cycle
Elapsed time to completion t (hr) and ratio to nominal capacity
Capacity C_n/ C₀Was measured. Two tests at 0 ° C and 25 ° C
From the data obtained from
Time required for CC mode charging and specific capacity C / C ₀connection of
Determine the coefficients A and B in equation (1), and₀= 1.089 × t^0.114 (3) was created.

Separately, the same type of prismatic Li-ion battery (nominal capacity 600 mAh) was used to charge
A (1.0 CmA), charge upper limit voltage 4.1 V, charge time 3
Time constant current constant voltage (CC-CV) charging,
Discharge current 600 mA (10 CmA), discharge end voltage 2.
And discharge of 75V, the charge-discharge cycle across the rest of the 10 minutes was performed 12 cycles between charging and discharging, the nominal capacity of the duration of the CC mode charge for each cycle t and (hr) discharge capacity C _n ratio 600mAh capacity _{C n} /
It was recorded and C _0.

The relational equation (3) was applied to the results of the charge / discharge cycle test thus obtained, and the maximum and minimum errors were obtained. As a result, the maximum error -21.7%, the minimum error-
1.0%.

Similarly, 2 data units, 3 data units, 5 data units, 10 data units, 11 data units,
Each of the relational expressions prepared using each of the data and the 15 data was applied to the above test results, the maximum and minimum errors were obtained, and the accuracy of the relational expression based on the number of data was examined.

FIG. 6 shows the results. That is, FIG. 6 is a diagram showing the number of data (data point / test in the figure) and the absolute value width of the error used for creating the relational expression. The upper limit is the maximum error (absolute value) and the lower limit is the minimum error (absolute value). Value).

As is apparent from FIG. 6, according to the relational expression prepared by using two or more data from each of the tests at 0 ° C. and 25 ° C., the error is within ± 20% and a highly accurate relational expression can be obtained. Was. According to the relational expression created using only one data for each test, an error may exceed ± 20%, which is not preferable. In addition, according to the relational expression created by 11 data or more, it became clear that there was almost no difference from the accuracy of 2 data or more and 10 data or less. (Example 3) In order to create a relational expression for a Li-ion battery, a Li-ion battery of the same type as that used in Example 1 was used, and at 0 ° C and 25 ° C, the charging current value was 600 mA (charging current value). Rate 1.0C, 1.0CmA), charge upper limit voltage 4.1V, constant current constant voltage (C
C-CV) charging, and discharging is performed at a current value of 600
mAh (discharge current rate: 1.0 C, 1.0 CmA), discharge end voltage: 2.75 V, 5 cycles of 1 hour between charging and discharging, with a pause between charging and discharging, starting charging in each cycle The elapsed time t (hr) from the time to the completion of the charging in the CC mode, and the specific capacity C _n / C _{0 with} respect to the nominal capacity
Was measured. When a relational expression was created based on this result, C / C ₀ = 1.015 × t ^0.0794 (4) was obtained.

A used prismatic Li-ion battery of the same kind as that used to create the above relational expression was collected, and the charging current was 600 mA (1.0 CmA), the charging upper limit voltage was 4.1 V,
The charging by the constant current constant voltage (CC-CV) method with the charging time of 3 hours, the discharging of the discharging current of 600 mA (1.0 CmA), the discharging end voltage of 2.75 V, and the pause of 10 minutes between charging and discharging are performed. The charge / discharge cycle is performed three times, and the required time t (h
r) and the specific capacity C _n / C _{0 of the} discharge capacity with respect to the nominal capacity of 600 mAh were recorded.

By applying the relational expression (4) to the obtained result,
The accuracy was examined.

FIG. 7 shows the results. That is, FIG. 7 shows the time required t for charging the deteriorated battery in the CC mode and the specific capacity C _n /
A diagram illustrating a relationship between the C _0, in FIG., 7-A is a curve showing the relationship of (4), 7-B is in the present invention was prepared in Example 1 shown for comparison 7C is a curve showing a value 20% smaller than that of the relational expression (4), that is, a curve showing an error of −20%.

As is clear from FIG. 7, the curve 7-B showing the relational expression (2) in the present invention shown as a comparative example is
While all the obtained data exist very close to each other and show high judgment accuracy, the relational expression (4) obtained in the present embodiment greatly deviates from the data and has an error of -20. %, The data exists at a position lower than%, which indicates that the error is large and is not preferable. That is, it is understood that the relational expression (2) created in the first embodiment is more suitable for capacity estimation than the relational expression (4) obtained in the present embodiment. (Example 4) In order to create a relational expression of a Li-ion battery, using a Li-ion battery of the same type as that used in Example 1 and a test at 0 ° C and 25 ° C, the charging current value was 60 mA (charging current value). Rate 0.1C), charge upper limit voltage 4.1
V, constant-current constant-voltage (CC-CV) method with a charging time of 3 hours, and discharging with a current value of 600 mA (discharging current rate of 1.0 C) and a discharging end voltage of 2.75 V. pause for 5 cycles of 1 hour sandwiched condition between, the elapsed time until the CC mode charge completion from the time of start of charging in each cycle t (hr), was measured specific capacitance C _n / C ₀ to the nominal capacity . When a relational expression was created based on this result, C / C ₀ = 1.046 × t ^0.219 (5) was obtained.

Another used prismatic Li-ion battery of the same kind as that used to create the above relational expression (5) was procured, and the charging current was 60 mA (0.1 CmA), the charging upper limit voltage was 4.1 V, and the charging was performed. 30 days constant current constant voltage (CC-C
V) charge and discharge current 600mA / 1.0C
mA), four charge / discharge cycles with a one-hour pause between charge and discharge with discharge at a discharge end voltage of 2.75 V are performed, and the required time t (hr) for CC mode charge for each cycle ) and the discharge capacity _{C n} nominal capacity _C 0 of the (60
0 mAh) was recorded as the specific capacity C _n / C ₀ .

By applying the relational expression (5) to the obtained result,
The accuracy was examined.

FIG. 8 shows the results. That is, FIG. 8 shows that the required time t for charging the deteriorated battery in the CC mode and the specific capacity C _n /
FIG. 8 is a diagram showing a relationship with C ₀ , where 8-A is a curve showing the above-mentioned relational expression (5), and 8-B is a curve in the present invention created in Example 1 shown for comparison. It is a curve which shows relational expression (2).

As is clear from FIG. 8, both the relational expression (5) obtained in the present embodiment and the relational expression (2) of the comparative example obtained in the first embodiment exist close to all data. Although all of them show high determination accuracy, the relational expression (2) of the first embodiment shown as a comparative example enables a higher accuracy deterioration determination than the relational expression (5) obtained in the present embodiment. You can see. Therefore, in the test performed at a higher temperature among the two different set temperatures, which is performed to obtain the relational expression, it is more preferable that the charging time be 3 days or more and 10 days or less than 3 hours or more and 10 days or less. It turned out to be favorable. (Example 5) Using an 18650 size cylindrical Li-ion battery (nominal capacity of 1400 mAh), the upper limit voltage was set to 4.
1 V, and the charging current value is 1400 mA (1.0 Cm
A) The constant-current constant-voltage (CC-CV) type charging set in A) is performed, the discharging end voltage is set to 2.75 V, the discharging is performed with the discharging current value set to 2800 mA (2.0 CmA), and the charging is performed. In the cycle test in which a one-hour pause is set between each cycle and discharge, and this charge / discharge cycle is repeated, two types of set temperatures of 30 ° C. and 5 ° C. are set. The charge time per cycle is set to the seven values shown in Table 1 below from 2.5 hours to 11 days, and when the set temperature is 5 ° C., the charge time per cycle is set to 5 hours. carried out the test, 3.50 V was recorded and the time required t (hr) and the discharge capacity _{C n} specific capacitance _{C n} / _{C 0} to the nominal capacity _{C 0} of up to CC mode charge completion from each charge-discharge cycle . Test duration is 2
One day, t and C are calculated from the data of the test at 30 ° C. obtained during this period and the same number of data at 0 ° C.
The relational expression was created by determining the constants A and B of the relational expression (1) of / C ₀ . When the number of data was 5 or more for each test, a relational expression was created from each of the 5 data.

In addition, when the charging time at a test temperature of 30 ° C. is set to 7 days in the above test conditions,
A test was performed in which the charging current value was separately set to 46 mA (0.033 CmA), and the required time t from 3.5 V to the completion of the CC mode charging was determined, and the 3.5 V CC mode charging of the 1400 mA (1.0 CmA) test was performed. When the conversion ratio with the time required for completion was calculated, t (1.0) / t (0.03
3) = 0.030 was obtained.

Separately, a used cylindrical Li-ion battery (nominal capacity of 1350 mAh) of 18650 size was collected, set in a battery charge / discharge automatic test apparatus, the upper limit voltage was set to 4.1 V, and the charging current was set. The value was 44.6 mA (0.0
33 CmA), a constant current / constant voltage (CC-CV) method of charging with a charging time of 7 days was performed, then the current value was set to 2700 mA (2.0 CmA), and the discharge end voltage was 2 Perform a test set to .75V, and measure the required time t 'and discharge capacity C from 3.50V to the completion of CC mode charging.
It was recorded and specific capacity _{C m} / _{C 0} that against the nominal capacity _{C 0} of the _m. From the required time t ′, t = t ′ × (t (1.0) / t
(0.033)) = 0.030 t ′ and the value of t is substituted into the relational expressions obtained above to estimate the specific capacity C _e /
C ₀ was calculated, and the absolute value of the difference from the measured specific capacity C _m / C _0, and the absolute value of Err = (C _e / C ₀ −C _m / C ₀ ) were obtained.

Table 1 shows the results.

[0086]

[Table 1] Table 1 shows each charging time per cycle of a test for creating a relational expression in the present embodiment, the number of data per test used for the creation, the created relational expression, and the absolute value of the determination error as a result of applying the same. It is a table showing values.

As is clear from Table 1, in the charging time of 3 hours or more and 10 days or less, which is the condition of the relational expression in the present invention, all the judgment errors showed good accuracy of being within ± 20%. . On the other hand, in the relational expressions prepared in tests with charging times of less than 3 hours and more than 10 days, a large error exceeding ± 20% was generated, and it became clear that there was a problem in the determination accuracy. (Example 6) Using an 18650 size cylindrical Li-ion battery (1400 mAh nominal capacity), the upper limit voltage was set to 4.
1 V, and the charging current value is 1400 mA (1.0 Cm
A) The constant-current constant-voltage (CC-CV) type charging set in A) is performed, the discharging end voltage is set to 2.75 V, the discharging is performed with the discharging current value set to 2800 mA (2.0 CmA), and the charging is performed. In the cycle test in which a 1-hour pause is set between the discharge and the discharge, and the charge and discharge are repeated, the high-side set temperature is set to 20 ° C. and the low-side set temperature is set to
-11 ° C, -10 ° C, 0 ° C, 5 ° C, 6 ° C, and 15 ° C
The charging time per cycle is set to 7 days at the high temperature setting temperature (20 ° C), and the charging time per cycle is set to 5 hours for each test at the low temperature setting temperature. The test was performed for two cycles, and the required time t (hr) for CC mode charging and the specific capacity C _n / C _{0 of the} discharge capacity C _n with respect to the nominal capacity C ₀ were recorded for each charge / discharge cycle. The t and C / C / D values were obtained from two sets of data obtained from a test at a high temperature (20 ° C.) and one test at a low temperature.
To determine the constants A and B of equation of C ₀ (1) to create a six relational expressions.

In addition, of the above test conditions, 20
In the high temperature test at ℃, the charging current value was separately 46 mA
(0.033 CmA), and the required time t from 3.5 V to the completion of charging in the CC mode was determined.
When the conversion ratio from 3.5 V in the test of 0 mA (1.0 CmA) to the time required to complete the charging in the CC mode was obtained,
t (1.0) / t (0.033) = 0.29 was obtained.

Separately, the used cylindrical Li-ion battery of 18650 size (with a nominal capacity of 1350 m
Ah) was set in the automatic battery charge / discharge test apparatus,
In the same manner as described above, the upper limit voltage is set to 4.1 V, the charging current value is set to 44.6 mA (0.033 CmA), and the charging time is set to 7 days. Then, the current value is set to 2700 mA (2.0 Cm
Set A), were tested for setting the end voltage to 2.75 V, the required time t 'and the discharge capacity _C specific capacitance against the nominal capacity _{C 0} of the _{m C m} from 3.50V to CC mode charge completion
/ _{C 0} and were recorded.

From the required time t ', the conversion rate t (1.0) / t (0.033) = 0.029 of the time between the charging current values 0.033 CmA and 1.0 CmA obtained as described above is used. T = t ′ × (t (1.0) / t (0.033)) = 0.29
The value of t obtained as t ′ is substituted into each of the six relational expressions to calculate the estimated specific capacity C _e / C ₀ , and the absolute value of the difference from the measured specific capacity C _m / C ₀ , Err = (C and the absolute value of _{e / C 0 -C m / C} 0).

Table 2 shows the results. That is, Table 2 is a table showing the test temperature of the low-temperature side test performed for obtaining the relational expression in the present embodiment, the obtained relational expression, and the absolute value of the error as a result determined by applying this. .

[0092]

[Table 2] As is clear from Table 2, the set temperature of the low-temperature test to be performed for obtaining the relational expression is -10 ° C. or more and 5 ° C. or less, and the difference between the set temperatures of the high-temperature test and the low-temperature test is 1
When the temperature was 5 ° C. or more, a favorable result was obtained in which the judgment error was within ± 20%. (Example 7) Prismatic Li-ion battery (nominal capacity 600 mA
h) For charging three battery packs in series, the charging upper limit voltage is 12.3 V, the charging current value is 600 mA (1.0 CmA), and the convergence current value which is the threshold value for terminating charging is 60 m.
A charger was prepared having a function of performing charging by the constant current and constant voltage (CC-CV) method designated as A and determining the battery pack at the time of charging.

FIG. 9 shows the structural concept of the manufactured charger.
That is, FIG. 9 is a diagram showing the configuration of the charger manufactured in the present embodiment.
At terminals 22 and 23. Also, the charger 2
In contrast to Li, the Li-ion battery pack 24 is connected to the terminals 25 and 26 for charging and mounted. The charger 20 converts electricity supplied from the commercial power supply 21 into AC /
The DC current is converted by the DC converter 27 to a charging current,
While monitoring the pack voltage and monitoring the temperature with the thermistor 28, the power supply microcomputer 29 and the charge control microcomputer 30 determine the above-mentioned charging conditions, overcharge, overdischarge,
The battery pack 24 is charged by performing control for detecting and avoiding a dangerous state such as an abnormally large current or an abnormally high battery temperature.
The charging is stopped by the switch 31 when the charging is completed or when an abnormality is detected. Completion of charging and any abnormalities are displayed on the display unit 32 from the control microcomputer 30. The display unit 32 includes an LED for displaying a charge-related display.
(Light emitting diode, red indicates charging, green indicates charging completed), LED indicating deterioration judgment result (red indicates battery replacement, yellow indicates battery replacement soon, green indicates battery replacement unnecessary), An LCD (Liquid Crystal Display) for displaying a numerical value of the deterioration determination result and displaying an abnormality.

In the charging-related LEDs, the green LED is turned on only when charging is completed, the red LED is turned on during charging,
If any other abnormality is indicated, neither is lit.

In the LED indicating the deterioration judgment result, when the value of the estimated specific capacity C / C _{0 as} the deterioration judgment result is less than 60%, the red LED is turned on and the battery should be immediately replaced with a new battery pack. Is shown. When the value of the estimated specific capacity C / C ₀ is 60% or more and less than 70%, the yellow LED is turned on soon because the battery pack should be replaced within a few months, depending on the use conditions. Let it. Further, when the value of the estimated specific capacity C / C ₀ is 70% or more, the green LED is turned on because the battery pack is new or can be used for a long time and does not need to be replaced.

The LCD (Liquid Crystal Display) is installed for displaying information by characters. It indicates that it is difficult to perform normal charging, such as warning information relating to safety, such as improper installation of a battery pack, and indicates a deterioration determination result by a numerical value. In addition, in the case of a sudden stop of the commercial power supply, only when the voltage of the attached battery pack is higher than 8.25 V, a current is supplied from the attached battery pack and the power-off is displayed.

The deterioration judgment according to the present invention is performed by the charge control microcomputer 30 by using the relational expression (2) created in the first embodiment.
And the flow procedure shown in FIG. 10 is programmed and input in advance, the CC charging time t is measured by the built-in timer while using the monitoring of the battery voltage, and is applied to the above-mentioned relational expression (2) to obtain Li Deterioration determination of the ion battery pack is performed, and the determination result is displayed on the display unit 32.

In the case of the charger of this embodiment, since charging is not always performed after complete discharging, data on the time change of the charging voltage is input in advance to the charging control microcomputer, and charging is started. The battery pack voltage at the time is monitored, and 8.25 V (2.75 V / cell) or more and 12 V (4.0
V / cell) A voltage of 0.15 V increments equal to or less than 8.25 + 0.15 × n (n is an integer, 0 ≦ n ≦ 25). Start time measurement, charge upper limit voltage 1
The time t "from 2.3 V to the completion of CC mode charging is measured, and the input data is compared with the input data to convert the time t to the required CC mode charging time from 8.25 V to 12.3 V. Deterioration judgment is performed.

The microcomputer 30 for charge control shown in FIG.
Is as follows. That is, Procedure A: Attach the battery pack to the charger and start charging,
Monitor pack voltage. Monitor with a voltage monitor whether the pack voltage V has reached the value satisfying V = 8.25 + 0.15 × n (n is an integer, 0 ≦ n ≦ 25) (6). Procedure B: Equation (6) above When the pack voltage V reaches the value to be satisfied, the time measurement is started. The timer counter continues to the charging upper limit voltage of 12.3 V. Procedure C: When the pack voltage V reaches the charging upper limit voltage of 12.3 V, time measurement ends. Charge start voltage is discharge end voltage 8.
In the case of 25V, this time t is used for the deterioration judgment as it is. Procedure D: When the charging start voltage is higher than 8.25V,
The measured time is compared with data on the time change of the charging voltage stored in advance and calculated from 8.25 V to 12.
It is converted to the required charging time in the CC mode up to 3 V, and this value is used as t for deterioration determination. By substituting the obtained time t equation (2), the estimated specific capacity C / C ₀ calculated, Step E: displaying the results calculated in the LCD and LED.
According to the value of the specific capacity as the determination result, any one of the red, yellow, and green LEDs is turned on as described above, and
The numerical value is displayed on the D display. The LCD display displays for 30 seconds and the LED turns on when the charger is connected to commercial power.

Using the charger configured as described above,
A used battery pack of the same type was attached and charged.
4.5 minutes after the start of charging, the deterioration judgment result is displayed and the LCD
The display showed 65% and the yellow LED was turned on. Charging was completed in about 2.5 hours. The charged battery pack was placed in an automatic battery charge / discharge tester, and the discharge current value was 600 mA (1.0 CmA) and the discharge end voltage was 8.25.
When constant current discharge was performed at a voltage of V, the discharge capacity was found to be 414.2 mAh. This was 69% in terms of specific capacity, and the error in capacity estimation was about 4%.

As described above, it has been clarified that the charger having the charging function according to the present invention can perform a highly accurate deterioration determination. (Embodiment 8) Charge upper limit voltage 12.3 V, charge current 600
Li ion of the configuration shown in FIG. 3 which is mounted on a small portable information terminal device having a function of performing constant current constant voltage (CC-CV) mode charging under the condition of mA (1.0 CmA) and a convergence current value of 60 mA. A battery pack was manufactured. The battery pack is composed of square cells (nominal capacity 600 mAh) 12-1, 12-2,
And 12-3 three-cell series packs with protective I
Similar to the relational expression (2) and C shown in Example 7,
Basic data of the time change of the charging voltage is input in advance, and even if the battery is charged from a pack voltage higher than the discharge end voltage 8.25V, the charging time in the constant current (CC) mode from 8.25V to 12.3V is calculated. The calculation is made possible.

The memory of the protection IC 13 in the battery pack having the structure shown in FIG.
The voltages at both ends of each of the cells 1, 12-2 and 12-3 are Vcc and V
Monitored by ss, from a predetermined starting voltage Vs which is equal to or higher than the discharge end voltage Vd in the CC mode charging and lower than the charging upper limit voltage Vc, higher than Vs, V = 8.25 + 0.15 × n (n is (Integer, 0 ≦ n ≦ 25) The elapsed time t from the closest voltage V satisfying (6) to the charging upper limit voltage 12.3 V at which the CC mode charging is completed is counted, and the value of the measured time t is counted. To the relational expression (2)
, A program for calculating the specific capacity C / C ₀ by substituting and calculating the specific capacity is input in advance.

The result of the calculation is output to the main body of the information terminal device on which the battery pack is mounted through the terminal 19 for display on the liquid crystal display of the main body.

On the liquid crystal display, the numerical value as the determination result is displayed in percentage, and the ratio corresponding to the percentage numerical value of the length of the bar is indicated by solid color.

An instruction for determining deterioration is issued simultaneously with the start of charging from the device main body. The procedure flow for performing the deterioration determination is the same as FIG. 10 except that the result is displayed on the display of the device main body and the result is sent to the main body in FIG.

After the battery pack having such a configuration was attached to the information terminal device and used for one hour, charging was started by connecting to a commercial power source, and the display displayed after the charging was started. The pack determination result was displayed as 87%. After confirming that the sign of charge completion appears on the display, turn off the information terminal device, remove and attach the battery pack, connect to the battery charge / discharge automatic test device using an appropriate connection cord, and discharge. Current 600mA (1.0C
mA), discharge was performed at a discharge end voltage of 8.25 V, and the capacity was measured. As a result, the discharge capacity was 534.6 mAh, and the specific capacity was 89.1%.

Accordingly, it has been found that the judgment result by the deterioration judging function mounted on the battery pack according to the present invention shows an excellent judgment accuracy of + 2.1%.

[0108]

As described above, by implementing the present invention, a simple method for estimating the capacity of a Li-ion battery, Li
It is possible to provide a Li-ion battery pack having a simple method and apparatus for determining the deterioration of an ion battery, and a Li-ion battery pack including means for estimating the capacity of the battery and warning the deterioration of the battery as necessary. It can make a huge contribution in the management of ion batteries.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the concept of a change in a battery voltage V and a charging current value I in a constant current constant voltage (CC-CV) method charging, which is a general charging method of a Li-ion battery.

FIG. 2 is a diagram showing one configuration concept around a general power supply unit of a Li-ion battery mounted device to which the method for determining deterioration of a Li-ion battery according to the present invention is specifically applied.

FIG. 3 is a diagram illustrating an example of a general circuit configuration of a Li-ion battery pack having a deterioration determination function according to the present invention.

FIG. 4 is a diagram showing a relationship between an elapsed time t and a specific capacity showing a result of a charge / discharge cycle test in Example 1 of the present invention.

FIG. 5 is a diagram showing a relationship between a required time t of CC mode charging and a specific capacity obtained in a charge / discharge cycle in Example 1 of the present invention.

FIG. 6 is a diagram illustrating the number of data and the absolute value width of an error used for creating a relational expression performed in the second embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a CC mode charging time required for a deteriorated battery and a specific capacity, which is a result of a test performed in Example 3 of the present invention.

FIG. 8 is a diagram illustrating a relationship between a CC mode charging required time t and a specific capacity, which is a result of a test performed in Example 4 of the present invention.

FIG. 9 is a diagram showing a configuration of a charger manufactured in Embodiment 7 of the present invention.

FIG. 10 is a flowchart showing a deterioration determination procedure performed in a seventh embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power supply part, 2a, 2b, 2c ... Li ion battery, 3 ...
Battery control unit, 4 charger, 5 logic unit, 6 interface, 7 CPU, 8 memory, 9 keyboard controller, 10 wiring, 11 battery main unit, 12-
1, 12-2, 12-3: Li-ion battery, 13: IC for protection, 14-A, 14-B, 14-C, 14-1, 14-
2, 14-3: FET, 15: PTC element, 16: current fuse, 17: plus terminal, 18: minus terminal, 1
9: terminal for information output and control, 20: charger, 21: commercial power supply, 22, 23 ... terminal for connecting the commercial power supply and the charger, 24: Li-ion battery pack, 25,
26 ... A terminal for connecting the charger and the battery pack, 27 ... A
C / DC converter, 28 ... Thermistor, 29 ... Power supply microcomputer, 30 ... Charge control microcomputer, 31 ... Switch,
32 ... Display unit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 7/10 H02J 7/10 BHF term (Reference) 2G016 CA00 CB12 CB31 CB32 CB33 CC01 CC04 CC06 CC07 CC13 CC27 CC28 CD06 CD14 CE02 CE31 5G003 AA01 BA01 CA03 CB06 EA05 EA08 GA01 GC05 5H030 AA03 AA04 AA06 AA08 AA10 AS11 BB02 BB03 DD05 DD06 DD08 FF41 FF42 FF52 FF66 FF68 5H040 AA06 AA36 AA09 NN AT01

Claims (8)

[Claims] 1. A method for estimating the capacity of a lithium ion battery, the method comprising: when charging a lithium ion battery by a constant current constant voltage method, when a charging voltage during constant current charging reaches a preset voltage Vs. Calculating the estimated capacity C of the lithium ion battery using the time t until the charging condition is switched from the constant current to the constant voltage, and calculating the estimated capacity C using the time t. 2. A capacity estimation method of a lithium ion battery according to claim 1, the charging current of the constant current charging when the nominal capacity of the lithium ion battery and C ₀ C
The time t is determined as ₀ / (30 hours) or more and C ₀ / (1 hour) or less, and the estimated capacity C of the lithium ion battery is expressed by a relational expression using the time t, C / C ₀ = A × t ^B. (1) (where A and B are the lithium ion battery and the voltage V
s and a positive value constant determined by the charging current during the constant current charging). 3. A constant current / constant voltage method using a lithium ion battery whose capacity is to be estimated or a lithium ion battery of the same type as the lithium ion battery, wherein a single charging time is 3 hours or more and 10 days or less. A charge / discharge cycle having a charge period, a discharge period, and a pause period provided between the charge period and the discharge period as necessary is repeated twice or more, and in each cycle, the charge during the constant current charge is performed. A time t _n (where n is a number assigned to each cycle) from a time when the voltage reaches a preset voltage Vs to a time when the charging condition is switched from a constant current to a constant voltage, and the discharge current was recorded and discharge capacity C _n obtained by integrating with respect to time, recorded from the t _n and the discharge capacitance C _n said time, a in the above equation (1), the value of B 3. The method for estimating the capacity of a lithium ion battery according to claim 2, wherein: 4. A method for judging deterioration of a lithium ion battery, wherein the estimated specific capacity C of the lithium ion battery is calculated by the method for estimating the capacity of a lithium ion battery according to claim 1, 2 or 3, and the estimated capacity is calculated. A method for determining deterioration of a lithium ion battery, comprising determining that the lithium ion battery has deteriorated when C becomes smaller than a predetermined limit capacity C _min . 5. A device for judging deterioration of a lithium ion battery, wherein when charging the lithium ion battery by a constant current / constant voltage method, a charging voltage during constant current charging reaches a preset voltage Vs. 4. A means for measuring a time t from a point of time when the charging condition is switched from a constant current to a constant voltage, and using the time t, the method for estimating the capacity of a lithium ion battery according to claim 1, 2 or 3. An arithmetic circuit for calculating the estimated capacity C of the ion battery, and when the estimated capacity C calculated by the arithmetic circuit becomes smaller than a preset limit capacity C _{min, this} indicates deterioration of the lithium ion battery. A means for outputting a signal. 6. A lithium ion battery pack provided with charge / discharge control means having a built-in IC.
C is a memory for storing a numerical value used for calculating the estimated capacity C of the lithium ion battery in the lithium ion battery pack, and an additional IC when the numerical value is stored in the memory. An arithmetic circuit for calculating the estimated capacity C by the method for estimating the capacity of a lithium ion battery according to claim 1, 2, or 3 from the time t and the numerical value when the ion battery is charged by the constant current and constant voltage method. A lithium-ion battery pack, comprising: 7. When the estimated capacity C of the lithium ion battery in the lithium ion battery pack calculated by the arithmetic circuit becomes smaller than a preset limit capacity C _{min of the} lithium ion battery. 7. The lithium ion battery pack according to claim 6, further comprising means for outputting a warning indicating capacity deterioration. 8. The lithium ion battery pack according to claim 7, wherein the warning is a warning by an electric signal, a warning by displaying characters or images, a warning by a signal sound, or a warning by voice.