JP2013190259A - Method for measuring derivative of open circuit voltage with respect to battery temperature, device for measuring derivative of open circuit voltage with respect to battery temperature, battery temperature estimation method, battery temperature estimation device, battery degradation state prediction method, and battery degradation state prediction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for measuring fundamental data for obtaining entropy change with high accuracy in a secondary battery etc.SOLUTION: In a method of measuring a derivative of open circuit voltage with respect to the temperature of a battery comprising secondary batteries, the open circuit voltage Vof a battery 11 is measured by a voltage measuring device 41 and the temperature T of the battery 11 is measured by a temperature measuring device 31, on the condition that temperature variations of the battery 11 are not greater than the temperature measurement limit of the temperature measuring device 31 and the condition that open circuit voltage variations of the battery 11 are not greater than the voltage measurement limit of the voltage measuring device 41. Based on those measurement results, the derivative of the battery open circuit voltage Vwith respect to the battery temperature T, namely, δV/δT, is obtained.

Description

  The present disclosure relates to a method for measuring a differential coefficient of an open-circuit voltage using a battery temperature as a variable, a device for measuring a differential coefficient of an open-circuit voltage using a battery temperature as a variable, a battery temperature estimating method, a battery temperature estimating apparatus, a battery The present invention relates to a deterioration state prediction method and a battery deterioration state prediction device.

  The characteristics such as the internal resistance value, the degree of deterioration, and the relative remaining capacity, which are difficult to directly measure in spite of important characteristics as the state of the secondary battery, are often estimated based on the discharge current and the open voltage. And the influence of temperature on these characteristics cannot be ignored. Therefore, in order to improve the estimation accuracy of these characteristics, it is necessary to measure temperature dependency for each characteristic to be estimated. However, such work requires enormous time and labor. In addition, in order to accurately predict the life of the secondary battery and estimate the discharge capacity, it is essential to predict the temperature change of the secondary battery, and in this case, not only the heat generation due to the internal resistance of the secondary battery. Also, it is necessary to take into account the heat absorption and heat generation due to the entropy change. Further, in the life prediction of the secondary battery, if the deterioration mode can be determined in the initial state, the life prediction accuracy of the secondary battery is improved. However, at present, it is very difficult to determine the early deterioration mode of the secondary battery.

  A battery deterioration estimation method including a plurality of unit cells is known from, for example, Japanese Patent Application Laid-Open No. 2010-127729. In the technology disclosed in this patent publication, an equivalent circuit having parameters that take into account electrode reaction and diffusion reaction is set as an internal resistance component of the battery, and the state of the battery is measured. Finally, the capacity maintenance rate of the battery is estimated. At this time, the battery temperature is measured as a measurement of the state of the battery, and the temperature correction is performed on the estimated value of the parameter set in consideration of at least the electrode reaction. I do.

  Also, a method for calculating the travelable distance of an electric vehicle from the remaining electric energy of the secondary battery for the electric vehicle is known from, for example, Japanese Patent Laid-Open No. 10-108301. In the technology disclosed in this patent publication, the battery temperature and the open circuit voltage at that time are detected, and the amount of discharged electricity and the battery power at a constant temperature under a constant temperature that has been experimentally determined in advance. From the relationship between the terminal voltage and the calorific value due to the entropy change of the battery reaction, the total calorific value and effective work amount of the battery during the discharge of a certain small amount of electricity are calculated. The process of calculating the battery temperature in the next constant small electric quantity discharge section from the specific heat is repeated until the battery terminal voltage exceeds the discharge end voltage, and the travelable distance is calculated from the total effective work amount up to that point .

JP 2010-127729 JP-A-10-108301

  However, Japanese Patent Laid-Open No. 10-108301 does not specifically mention how to obtain the entropy change with high accuracy, and Japanese Patent Laid-Open No. 2010-127729 determines the deterioration mode in the initial state. No mention is made regarding the method, and the deterioration state of the secondary battery cannot be predicted.

  Accordingly, a first object of the present disclosure is to provide a method and a measurement apparatus for measuring basic data for obtaining entropy change with high accuracy in a secondary battery or the like. A second object of the present disclosure is to provide a temperature estimation method and a temperature estimation device that can estimate the temperature of a secondary battery or the like with high accuracy. Furthermore, a third object of the present disclosure is to provide a secondary battery deterioration state prediction method and a deterioration state prediction apparatus capable of predicting a deterioration state in a secondary battery with high accuracy.

A method for measuring a differential coefficient of an open-circuit voltage using a temperature of a battery according to the first aspect of the present disclosure as a variable (hereinafter referred to as “the battery according to the first aspect of the present disclosure. (Sometimes referred to as “∂V _OC / ∂T) measurement method”) is a method for measuring the differential coefficient of the open-circuit voltage with the temperature of the battery comprising the secondary battery as a variable,
With the battery temperature fluctuation below the temperature measurement limit of the temperature measurement device and the battery open-circuit voltage fluctuation below the voltage measurement limit of the voltage measurement device, measure the open-circuit voltage of the battery with the voltage measurement device, and The temperature of the battery is measured by a temperature measuring device, and the differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the battery temperature T as a variable is obtained based on the open circuit voltage measurement result and the temperature measurement result. .

A method for measuring a differential coefficient of an open-circuit voltage using the temperature of the battery according to the second aspect of the present disclosure as a variable for achieving the first object (hereinafter referred to as “the battery of the second aspect of the present disclosure (Sometimes referred to as “∂V _OC / ∂T) measurement method”) is a method for measuring the differential coefficient of the open-circuit voltage with the temperature of the battery comprising a lithium ion battery as a variable,
In the state where the lithium ion diffusion reaction has not occurred, the open circuit voltage of the battery is measured by the voltage measuring device, and the temperature of the battery is measured by the temperature measuring device. Based on the open voltage measurement result and the temperature measurement result, The differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T as a variable is obtained.

The battery temperature estimation method according to the first aspect of the present disclosure for achieving the second object is a battery temperature estimation method including a secondary battery,
In advance, measure the open circuit voltage of the battery with the voltage measurement device in a state where the temperature variation of the battery is below the temperature measurement limit of the temperature measurement device and the open circuit voltage variation of the battery is below the voltage measurement limit of the voltage measurement device. The battery temperature is measured by a temperature measuring device, and the differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC using the battery temperature T as a variable based on the open circuit voltage measurement result and the temperature measurement result. Seeking
The battery temperature is estimated based on the measured battery temperature, the measured charge / discharge current of the battery, and (∂V _OC / ∂T) obtained in advance.

The battery temperature estimation method according to the second aspect of the present disclosure for achieving the second object is a battery temperature estimation method including a lithium ion battery,
In the state where the diffusion reaction of lithium ions has not occurred in advance, the open circuit voltage of the battery is measured by the voltage measuring device, and the temperature of the battery is measured by the temperature measuring device, based on the open voltage measurement result and the temperature measurement result, _Obtain the differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable,
The battery temperature is estimated based on the measured battery temperature, the measured charge / discharge current of the battery, and (∂V _OC / ∂T) obtained in advance.

In the battery deterioration state prediction method comprising the secondary battery of the present disclosure for achieving the third object,
(A) The relationship between the voltage between terminals and the relative remaining capacity during discharging or charging in the state where the temperature fluctuation of the battery is below the temperature measurement limit of the temperature measuring device, and the relationship between the initial terminal voltage and the relative remaining capacity Sought as, then
(B) Repeat charging / discharging of the battery a desired number of times, then
(C) In a state where the temperature fluctuation of the battery is not more than the temperature measurement limit of the temperature measuring device, the relationship between the inter-terminal voltage during discharging or charging and the relative remaining capacity is as follows: The deterioration state of the battery is predicted based on the relationship between the initial inter-terminal voltage and the relative remaining capacity and the relationship between the inter-terminal voltage after charging and discharging and the relative remaining capacity.

An apparatus for measuring a differential coefficient of an open-circuit voltage with the temperature of the battery according to the first aspect of the present disclosure as a variable for achieving the first object (hereinafter referred to as “the battery of the first aspect of the present disclosure. (Sometimes referred to as “∂V _OC / ∂T) measuring device”) is a measuring device for the differential coefficient of the open-circuit voltage with the temperature of the battery comprising the secondary battery as a variable,
A voltage measuring device for measuring the open-circuit voltage of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
With the temperature control device, the battery temperature fluctuation is less than or equal to the temperature measurement limit of the temperature measurement device, and the battery open-circuit voltage fluctuation is less than or equal to the voltage measurement limit of the voltage measurement device. And the temperature of the battery is measured by the temperature measuring device, and (∂V _OC / ∂T) is obtained by the arithmetic unit based on the open circuit voltage measurement result and the temperature measurement result.

A method for measuring a differential coefficient of an open-circuit voltage using the temperature of the battery according to the second aspect of the present disclosure as a variable for achieving the first object (hereinafter referred to as “the battery of the second aspect of the present disclosure (Sometimes referred to as “∂V _OC / ∂T) measuring device”) is a (∂V _OC / ∂T) measuring device for a battery comprising a lithium ion battery,
A voltage measuring device for measuring the open-circuit voltage of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In a state in which the lithium ion diffusion reaction has not occurred, the voltage control device measures the open circuit voltage of the battery, and the temperature measurement device measures the battery temperature. Based on the temperature measurement result, (∂V _OC / ∂T) is obtained by the arithmetic unit.

The battery temperature estimation device according to the first aspect of the present disclosure for achieving the second object is a battery temperature estimation device including a secondary battery,
A voltage measuring device for measuring the open-circuit voltage of the battery,
A current measuring device for measuring the charge / discharge current of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In advance, with the temperature control device, the battery temperature fluctuation is less than the temperature measurement limit of the temperature measurement device, and the battery open-circuit voltage fluctuation is less than the voltage measurement limit of the voltage measurement device. The open-circuit voltage is measured, and the temperature of the battery is measured by the temperature measuring device. Based on the open-circuit voltage measurement result and the temperature measurement result, (演算 V _OC /） T) is obtained by the arithmetic device and is obtained (∂ V _OC / ∂T) is stored in the arithmetic unit,
The arithmetic device further estimates the battery temperature based on the actual measured battery temperature, the stored (∂V _OC / ∂T), and the actual measured charge / discharge current of the battery.

The battery temperature estimation device according to the second aspect of the present disclosure for achieving the second object is a battery temperature estimation device comprising a lithium ion battery,
A voltage measuring device for measuring the open-circuit voltage of the battery,
A current measuring device for measuring the charge / discharge current of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In a state in which the lithium ion diffusion reaction has not occurred in advance, the open circuit voltage of the battery is measured by the voltage measuring device and the open circuit voltage is measured by the temperature measuring device. Based on the result and the temperature measurement result, (演算 V _OC / ∂T) is obtained by the computing device, and the obtained (∂V _OC / ∂T) is stored in the computing device,
The arithmetic device further estimates the battery temperature based on the actual measured battery temperature, the stored (∂V _OC / ∂T), and the actual measured charge / discharge current of the battery.

In order to achieve the third object described above, a battery deterioration state prediction apparatus comprising the secondary battery of the present disclosure is provided.
A charging / discharging device for charging / discharging the battery,
A voltage measuring device for measuring the voltage between the terminals of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
Arithmetic unit,
With
The relationship between the terminal voltage and the relative remaining capacity during discharging or charging is the initial terminal voltage and the relative remaining capacity when the battery temperature fluctuation is below the temperature measurement limit of the temperature measuring device by the temperature controller. Is calculated by the arithmetic unit as
The charging / discharging device repeats charging / discharging of the battery a desired number of times,
In a state where the temperature fluctuation of the battery is not more than the temperature measurement limit of the temperature measurement device by the temperature control device, the relationship between the voltage between the terminals at the time of discharging or charging and the relative remaining capacity is relative to the voltage between the terminals after charging and discharging. The relationship with the remaining capacity is determined by the arithmetic device, and further based on the relationship between the initial inter-terminal voltage and the relative remaining capacity, and the relationship between the inter-terminal voltage after charging and discharging and the relative remaining capacity, by the arithmetic device. The battery deterioration state is predicted.

In the battery (∂V _OC / ∂T) measurement method or measurement device according to the first aspect of the present disclosure, the battery temperature fluctuation is less than the temperature measurement limit of the temperature measurement device, and the open circuit voltage of the battery In the state where the fluctuation is less than the voltage measurement limit of the voltage measurement device, and in the battery (∂V _OC / ∂T) measurement method or measurement device according to the second aspect of the present disclosure, In a state where no diffusion reaction occurs, the open circuit voltage and temperature of the battery are measured. Thus, by measuring the open-circuit voltage of the battery with high accuracy, (∂V _OC / ∂T), which is basic data for obtaining the entropy change, can be obtained with high accuracy. Since such (∂V _OC / ∂T) can be obtained with high accuracy, for example, battery temperature estimation described below can be performed with high accuracy.

  Further, in the battery temperature estimation method or temperature estimation device according to the first aspect of the present disclosure, the battery temperature fluctuation is less than the temperature measurement limit of the temperature measurement apparatus, and the battery open-circuit voltage fluctuation is voltage measurement. In a state where the voltage measurement limit of the device is below the limit, and in the battery temperature estimation method or temperature estimation device according to the second aspect of the present disclosure, in the state where no lithium ion diffusion reaction occurs, Measure the open circuit voltage and temperature. Therefore, the temperature of the battery can be estimated with high accuracy.

  Furthermore, in the battery deterioration state prediction method or the battery deterioration state prediction device including the secondary battery according to the present disclosure, the battery temperature fluctuation is equal to or lower than the temperature measurement limit of the temperature measurement device at the time of discharging or charging. Since the relationship between the terminal voltage and the relative remaining capacity at the time is obtained, the relationship between the initial terminal voltage and the relative remaining capacity with high accuracy and the relationship between the terminal voltage after charging and discharging and the relative remaining capacity can be obtained. it can. As a result, it is possible to predict the deterioration state of the battery with high accuracy.

FIG. 1 is a conceptual diagram of a battery (∂V _OC / ∂T) measuring device of Example 1, a battery temperature estimating device of Example 4, and a battery deterioration state predicting device of Example 5. 2A, 2B and 2C are diagrams each schematically showing a temperature distribution in the length direction of the secondary battery, and schematically showing an open-circuit voltage distribution in the length direction of the secondary battery. It is a figure which shows, and a figure which shows the relative remaining capacity dependence of (( _VOC ) / (T)) typically. 3A, 3 </ b> B, and 3 </ b> C are graphs schematically showing the initial / discharge curve and the post-charge / discharge curve measured in Example 5. FIG.

Hereinafter, although this indication is explained based on an example with reference to drawings, this indication is not limited to an example and various numerical values and materials in an example are illustrations. The description will be given in the following order.
1. (∂V _OC / ∂T) measurement method, battery (∂V _OC / ∂T) measurement device, battery temperature estimation method, battery temperature estimation device, battery deterioration state prediction method, and 1. General description of battery deterioration state prediction device Example 1 (Battery (∂V _OC / ∂T) Measuring Method and Battery (∂V _OC / ∂T) Measuring Device According to First and Second Aspects of Present Disclosure))
3. Example 2 (Modification of Example 1)
4). Example 3 (another modification of Example 1)
5. Example 4 (battery temperature estimation method and battery temperature estimation apparatus according to first and second aspects of the present disclosure)
6). Example 5 (battery deterioration state prediction method and battery deterioration state prediction device of the present disclosure), etc.

[Battery (∂V _OC / ∂T) Measurement Method, Battery (∂V _OC / ∂T) Measurement Device, Battery Temperature Estimation Method, Battery Temperature Estimation Device, Battery Degradation State Prediction Method, and , General description of battery deterioration state prediction device]
The battery (∂V _OC / ∂T) measurement method according to the second aspect of the present disclosure, the battery (∂V _OC / ∂T) measurement device according to the second aspect of the present disclosure, In the battery temperature estimation method according to the aspect or the battery temperature estimation apparatus according to the second aspect of the present disclosure, a state in which a lithium ion diffusion reaction has not occurred indicates that the battery temperature fluctuation is measured by the temperature measurement apparatus. It can be set as the state which is below the limit and the open circuit voltage fluctuation of the battery is below the voltage measurement limit of the voltage measuring device.

Battery (∂V _OC / ∂T) Measuring Method, Battery (∂V _OC / ∂T) Measuring Device, Battery Temperature Estimation According to First or Second Aspect of Present Disclosure Including Preferred Form In the method or the battery temperature estimation device, a voltage measurement device whose voltage measurement limit is 1 × 10 ⁻⁶ volts and a temperature measurement device whose temperature measurement limit is 1 × 10 ⁻² ° C. are used. Although preferable, it is not limited to this. It should be noted that a request for such a voltage measurement limit to the voltage measurement device and a request for such a temperature measurement limit to the temperature measurement device are such that the value of (∂V _OC / ∂T) is 10 ^{−4 to} 10 ⁻³ . Based on what is on the order.

Furthermore, the battery (∂V _OC / ∂T) measuring method and battery (∂V _OC / ∂T) measuring device according to the first or second aspect of the present disclosure including the preferred embodiments described above. Can be configured to obtain (∂V _OC / ∂T) related to the relative remaining capacity of the battery, or to obtain (∂V _OC / ∂T) related to the degree of deterioration of the battery. It can be. Here, examples of the deterioration degree of the battery include a decrease in the discharge capacity and an increase in the internal resistance value of the secondary battery. Thus, by measuring (∂V _OC / ∂T) according to each state (relative remaining capacity and degree of deterioration) and using this value for estimation of relative remaining capacity and degree of deterioration, relative remaining capacity and Correction due to temperature for estimating the degree of deterioration is not necessary. That is, the measurement for temperature correction becomes unnecessary.

The battery deterioration state prediction method or deterioration state prediction apparatus including the secondary battery according to the present disclosure is not limited, but uses a temperature measurement apparatus having a temperature measurement limit of 1 × 10 ⁻² ° C. In the battery deterioration state prediction method or deterioration state prediction apparatus comprising the secondary battery of the present disclosure including such a preferable configuration, the voltage measurement device having a voltage measurement limit of 1 × 10 ⁻⁶ volts is provided. Preferably used to measure the voltage across the terminals. Further, in the battery deterioration state prediction method or deterioration state prediction apparatus comprising the secondary battery of the present disclosure including these preferred configurations, the initial / discharge curve is determined from the relationship between the initial terminal voltage and the relative remaining capacity. After charging / discharging, determine the post-charge / discharge curve from the relationship between the inter-terminal voltage and the relative remaining capacity, and predict the deterioration state of the battery based on the initial / discharge curve and the post-charge / discharge curve be able to.

  Examples of the secondary battery in the present disclosure may include a lithium ion battery, a lead storage battery, a nickel / cadmium battery, and a nickel / hydrogen battery. The voltage measuring device and temperature measuring device to be used may be a well-known voltage measuring device and temperature measuring device. The temperature control device that controls the temperature of the battery can be composed of, for example, a Peltier element that heats and cools the battery, and a temperature control unit (temperature control circuit) that controls the operation of the Peltier element. The arithmetic device may be composed of, for example, a CPU and a memory.

Battery (∂V _OC / ∂T) Measuring Method, Battery (∂V _OC / ∂T) Measuring Device According to First or Second Aspect of Present Disclosure, First Aspect or Second of Present Disclosure The battery temperature estimation method, the battery temperature estimation device, or the battery deterioration state prediction method, and the battery deterioration state prediction device according to the above aspect are stored in a storage container that insulates the battery from the external environment. In the state, it is desirable to measure the open circuit voltage of the battery, the voltage between terminals, and the temperature of the battery, but the present invention is not limited to this.

Example 1 relates to a battery (測定 V _OC / ∂T) measurement method and a battery (∂V _OC / ∂T) measurement apparatus according to the first and second aspects of the present disclosure. Here, (∂V _OC / ∂T) of the battery is a state quantity proportional to the entropy change in the Gibbs energy change of the battery, and is a basic characteristic representing the chemical state of the battery.

(∂V _OC / ∂T) measuring method of a battery of Example 1 is (∂V _OC / ∂T) measuring method of a battery consisting of a secondary battery or a lithium ion battery. Then, in a state where the temperature variation of the battery is equal to or lower than the temperature measurement limit of the temperature measuring device and the open-circuit voltage variation of the battery is equal to or lower than the voltage measurement limit of the voltage measuring device [the battery according to the first aspect of the present disclosure (∂V _OC / ∂T) measurement method] or, in a state where no lithium ion diffusion reaction has occurred, [( _VOC / ∂T) measurement method of the battery according to the second aspect of the present disclosure], The battery open voltage V _OC is measured by the voltage measuring device, the battery temperature T is measured by the temperature measuring device, and the battery opening with the battery temperature T as a variable is measured based on the open voltage measurement result and the temperature measurement result. The differential coefficient (∂V _OC / ∂T) of the voltage V _OC is obtained.

The battery of (∂V _OC / ∂T) measuring apparatus 10 of the first embodiment, a battery (∂V _OC / ∂T) measuring apparatus comprising a rechargeable battery or a lithium ion battery,
A voltage measuring device (voltage measuring circuit) 41 for measuring the open circuit voltage V _{OC of the} battery;
A temperature measuring device (temperature measuring circuit) 31 for measuring the temperature of the battery;
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit 21 for obtaining a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
In addition,
A current measuring device (current measuring circuit) 42 for measuring the charge / discharge current of the battery;
It has. And
In a state where the temperature fluctuation of the battery is set to be less than or equal to the temperature measurement limit of the temperature measurement device 31 and the open-circuit voltage fluctuation of the battery is less than or equal to the voltage measurement limit of the voltage measurement device 41 by the temperature control device [first disclosed ((V _OC / ∂T) measuring device of battery according to aspect) or in a state where the lithium ion diffusion reaction is not generated by the temperature control device [battery according to the second aspect of the present disclosure (∂V _OC / ∂T) measuring device], the voltage measuring device 41 measures the open circuit voltage V _{OC of the} battery, and the temperature measuring device 31 measures the battery temperature T, and the open circuit voltage measurement result and the temperature measurement. Based on the result, (演算 V _OC / ∂T) is obtained by the arithmetic unit 21.

Specifically, as shown in the conceptual diagram of FIG. 1, the (∂V _OC / ∂T) measuring device 10 includes a voltage measuring device (voltage measuring circuit) 41, a current measuring device (current measuring circuit) 42, and a temperature measurement. A device (temperature measurement circuit) 31, temperature control devices 51, 52 </ b> A, 52 </ b> B, and an arithmetic device 21 are provided. Specifically, the temperature measuring device 31 is a secondary battery or a lithium ion battery (hereinafter collectively referred to simply as “secondary battery 11” or “secondary battery”). A temperature measuring unit 32 that contacts the outer surface and measures the temperature of the secondary battery 11 is provided. The temperature measuring device 31 and the temperature measuring unit 32 are connected by a wiring 33. The secondary battery 11 is stored in storage containers 61A and 61B that insulate the secondary battery 11 from the external environment. The storage containers 61 </ b> A and 61 </ b> B are divided into two for taking in and out the secondary battery 11. The temperature measuring unit 32 is attached to the storage containers 61A and 61B. The temperature control device includes Peltier elements 52A and 52B disposed in the upper and lower portions of the storage containers 61A and 61B, and a temperature control unit (temperature control circuit) connected to the Peltier elements 52A and 52B via wirings 53A and 53B. ) 51. Furthermore, the voltage measuring device 41 and the current measuring device 42 are connected to contact terminal portions 62A and 62B disposed on the upper and lower portions of the storage containers 61A and 61B via wirings 43A and 43B. The contact terminal portions 62A and 62B are in contact with the positive electrode and the negative electrode of the secondary battery 11, respectively. The arithmetic unit 21 includes a CPU and the like, and further includes a memory 22 that stores various programs and data, and a voltage / temperature memory 23 that stores voltage measurement values and temperature measurement values.

As the voltage measuring device 41 and the temperature measuring device 31, a voltage measuring device having a voltage measuring limit of 1 × 10 ⁻⁶ volts and a temperature measuring device having a temperature measuring limit of 1 × 10 ⁻² ° C. Use. In Example 1, (∂V _OC / ∂T) related to the relative remaining capacity of the secondary battery 11 is obtained.

In the measurement of (∂V _OC / ∂T) of the secondary battery 11, for example, first, the secondary battery 11 is fully charged. Specifically, the 18650 type which is a cylindrical cell was used as the secondary battery 11. In the fully charged state, the discharge capacity is, for example, 2000 mAh.

Then, the temperature control device is set so that the temperature of the secondary battery 11 is, for example, 10 ° C. In this case, actually, as shown in FIG. 2A, a temperature distribution is generated in the length direction of the secondary battery 11, but in the case of a cylindrical cell, an electrode is wound inside. As shown in FIG. 2B, the open circuit voltage V _OC of the secondary battery 11 becomes a value corresponding to the average value of the temperature distribution. The temperature distribution in the steady state can be easily calculated using a commercially available thermal fluid analysis program such as ANSYS CFD, CD-adapco STAR-CCM +, Autodesk Simulation CFD, or FLOW-3D. Therefore, it is relatively easy to calculate the average temperature of the secondary battery 11 with respect to the set temperature of the Peltier elements 52A and 52B.

Then, the temperature variation of the secondary battery 11 becomes less than the temperature measurement limit of the temperature measurement device 31 (0.01 ° C. or less), and the open-circuit voltage variation of the secondary battery 11 is the voltage measurement limit (1) of the voltage measurement device 41. In a state in which the voltage is equal to or less than microvolt), the open circuit voltage V _OC is measured by the voltage measuring device 41, and the temperature T of the secondary battery 11 is measured by the temperature measuring device 31. Alternatively, the open circuit voltage V _OC is measured by the voltage measuring device 41 and the temperature T of the secondary battery 11 is measured by the temperature measuring device 31 in a state where no lithium ion diffusion reaction occurs. In addition, although the time until it reaches such a state depends on the specification of the secondary battery 11, it is about 24 hours to 48 hours. Next, the temperature control device is set so that the temperature of the secondary battery 11 is, for example, 15 ° C. Then, the temperature variation of the secondary battery 11 becomes less than the temperature measurement limit of the temperature measurement device 31 (0.01 ° C. or less), and the open-circuit voltage variation of the secondary battery 11 is the voltage measurement limit (1) of the voltage measurement device 41. In a state in which the voltage is equal to or less than microvolt), the open circuit voltage V _OC is measured by the voltage measuring device 41, and the temperature T of the secondary battery 11 is measured by the temperature measuring device 31. In addition, although time until it reaches such a state is dependent on the specification of the secondary battery 11, it is about 10 minutes-30 minutes. Next, in this way, the temperature control device is set so that the temperature of the secondary battery 11 becomes, for example, 20 ° C., 25 ° C., 30 ° C., 35 ° C., 40 ° C. The temperature T of the _OC and the secondary battery 11 is measured. Then, the measurement results of the open circuit voltage V _OC and the temperature T of the secondary battery 11 are stored in the voltage / temperature memory 23 under the control of the arithmetic unit 21.

In this way, from the obtained open circuit voltage V _OC and the temperature T of the secondary battery,
V _OC = k ₁ × T + k ₀
Is obtained based on the least square method. The obtained coefficient k ₁ is a differential coefficient (∂V _OC / ∂T) of the open-circuit voltage V _OC of the secondary battery with the temperature T of the secondary battery as a variable, and 10 ⁻³ to 10 ⁻⁴ (volt / (° C). The coefficient of determination of the regression line was 0.99 or higher (for example, 0.9998). The open circuit voltage V _OC is about 100 microvolts to 10 millivolts.

Since such a high coefficient of determination is obtained, in order to shorten the measurement time, for example, measurement is performed at two points of 10 ° C. and 40 ° C., and the inclination is set as (∂V _OC / ∂T). If the change of (∂V _OC / ∂T) with respect to the temperature is large, or if the accuracy of the application may be reduced, for example, two points of 20 ° C and 25 ° C. There is no problem just to measure with.

Next, the secondary battery 11 is taken out from the storage containers 61A and 61B, and a certain amount of discharge is performed using a discharge device (not shown). Here, for example, a current amount (200 mAh) corresponding to 10% of the discharge capacity is discharged. The lithium ion diffusion reaction continues after discharge. After the secondary battery 11 is left indoors for 24 to 48 hours so that no lithium ion diffusion reaction occurs, the secondary battery 11 is stored in the storage containers 61A and 61B, and again the secondary battery. The temperature controller is set so that the temperature of 11 is, for example, 10 ° C. Then, the temperature variation of the secondary battery 11 becomes less than the temperature measurement limit of the temperature measurement device 31 (0.01 ° C. or less), and the open-circuit voltage variation of the secondary battery 11 is the voltage measurement limit (1) of the voltage measurement device 41. In a state in which the voltage is equal to or less than microvolt), the open circuit voltage V _OC is measured by the voltage measuring device 41, and the temperature T of the secondary battery 11 is measured by the temperature measuring device 31. Alternatively, the open circuit voltage V _OC is measured by the voltage measuring device 41 and the temperature T of the secondary battery 11 is measured by the temperature measuring device 31 in a state where no lithium ion diffusion reaction occurs. Further, as described above, the temperature control device is set so that the temperature of the secondary battery 11 is, for example, 15 ° C, 20 ° C, 25 ° C, 30 ° C, 35 ° C, 40 ° C. Similarly, the open circuit voltage V _OC and the temperature T of the secondary battery 11 are measured. Then, the measurement results of the open circuit voltage V _OC and the temperature T of the secondary battery 11 are stored in the voltage / temperature memory 23 under the control of the arithmetic unit 21.

The measurement of the discharge of the secondary battery 11 and the measurement of the open circuit voltage V _OC and the temperature of the secondary battery 11 are, for example, 20%, 30%, ..., 90% of the discharge capacity. Repeatedly. Then, based on the open-circuit voltage measurement result and the temperature measurement result, a differential coefficient (∂V _OC / ∂T) of the open-circuit voltage V _OC of the secondary battery using the temperature T of the secondary battery as a variable is obtained. Specifically, from the obtained open circuit voltage V _OC and the temperature T of the secondary battery, in the calculation device 21, at each current flow rate (relative remaining capacity of the secondary battery),
V _OC = k ₁ × T + k ₀
Is obtained based on the least square method. The obtained coefficient k ₁ is that of the secondary battery with the temperature T of the secondary battery as a variable at each current flow rate (relative remaining capacity of the secondary battery) as schematically shown in FIG. It is a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC . In this way, (∂V _OC / ∂T) related to the relative remaining capacity of the secondary battery can be obtained.

Here, the entropy change ΔS of the secondary battery is
ΔS = n · F · (∂V _OC / ∂T) (1)
It can be expressed as still,
n: number of electrons F: Faraday constant.

The relative remaining capacity dependence of (∂V _OC / ∂T) shown in (C) of FIG. 2 largely depends on the constituent material of the secondary battery, but the entropy change ΔS of the secondary battery is theoretically analyzed. If the graph shape of the relative remaining capacity dependency of (∂V _OC / ∂T) is known in advance, fitting to the measurement point of (T, V _OC ) gives an accurate ( (V _OC / T) data can be obtained. If it is difficult to apply such fitting, interpolation may be performed using a spline or the like, or data may be collected more finely.

In Example 1, as described above, the temperature variation of the secondary battery was less than the temperature measurement limit of the temperature measurement device, and the open-circuit voltage variation of the secondary battery was less than the voltage measurement limit of the voltage measurement device. In the state, or in the state where the lithium ion diffusion reaction does not occur, the open-circuit voltage and temperature of the secondary battery are measured. Thus, as a result of measuring the open circuit voltage of the secondary battery with high accuracy, (∂V _OC / ∂T), which is basic data for obtaining entropy change, can be obtained with high accuracy.

The second embodiment is a modification of the first embodiment. In Example 2, the curve [“(∂V _OC / ∂T, which is obtained in Example 1 and shows the dependency on the relative remaining capacity of (∂V _OC / ∂T) shown in FIG. 2C). ) Is called “curve”], the arithmetic device 21 determines the relative remaining capacity of the secondary battery. That is, (∂V _OC / ∂T) of the secondary battery 11 actually used is obtained, and the relative remaining capacity of the secondary battery 11 actually used at that time is obtained. Specifically, (T, V _OC ) of the secondary battery 11 is obtained in a state where it is actually used. In this case, the temperature measurement limit of the temperature measurement device 31 may be, for example, 0.1 ° C. or less, and the voltage measurement limit of the voltage measurement device 41 may be, for example, 0.1 millivolt or less. .

For example, during the discharge of the secondary battery, (T ₁ , V _OC-1 ), (T ₂ , V _OC-2 ) are obtained a plurality of times, for example, twice at appropriate time intervals. In this case, the voltage V _TV between the terminals of the secondary battery may be specifically measured while forcibly controlling the temperature of the secondary battery or capturing the temperature change caused by charging and discharging. Then, the open circuit voltage V _OC (V _OC-1 , V _OC-2 ) is calculated based on a known method in consideration of the voltage change caused by the internal resistance of the secondary battery and the voltage change due to charging / discharging. Thus, ∂V _OC / ∂T can be obtained based on the following equation.

∂V _OC / ∂T = (V _OC-1 -V _OC-2 ) / (T ₁ -T ₂ )

As shown in FIG. 2C, when there are three values of temperature T that match a certain value (∂V _OC / ∂T) (in FIG. 2C, “ a ”,“ b ”, and“ c ”). Accordingly, an approximate relative remaining capacity is calculated by the current integration method, and (∂V _OC / ∂ in the vicinity of the calculated relative remaining capacity (for example, in the vicinity of “a” in FIG. 2C). T) Pay attention to the curve. Then, the obtained matches the value of _{(∂V OC / ∂T) (∂V} OC / ∂T) of the state of charge in the curve value (in FIG. 2 in (C), indicated by "d") is, It is obtained as the relative remaining capacity of the secondary battery.

In the above process for determining the relative remaining capacity of the secondary battery, (∂V _OC / ∂T) is obtained, and this value is used for estimating the relative remaining capacity. It becomes unnecessary. Moreover, since the current integration method is used to obtain an approximate relative remaining capacity, temperature correction is unnecessary. Although the internal resistance has temperature dependence, if the measurement time interval is selected so that the temperature change between two points to be measured does not increase, the temperature dependence of the internal resistance can be ignored. The same applies to Example 3 described below.

The third embodiment is also a modification of the first embodiment. In Example 3, (∂V _OC / ∂T) related to the degree of deterioration of the secondary battery is obtained. Here, in Example 3, the deterioration degree of the secondary battery is defined as a decrease in the discharge capacity of the secondary battery. Specifically, for example, by repeating charging and discharging of the secondary battery, the discharge capacity is reduced, and at each stage of the reduction of the discharge capacity, the (∂V _OC / ∂T) curve is obtained in the same manner as in Example 1. Ask. Thus, a (∂V _OC / ∂T) curve related to the degree of deterioration of the secondary battery, that is, a (∂V _OC / ∂T) curve related to the discharge capacity can be obtained.

In the same manner as in Example 2, in the actually used secondary battery 11, a plurality (for example, two points) of (T, V _OC ), for example, (T ₁ , V _OC-1 ), ( T ₂ , V _OC-2 ), and (∂V _OC / ∂T) is obtained in the same manner as in Example 2, and the obtained (∂V _OC / ∂T) is determined as to which discharge capacity. The arithmetic unit 21 checks whether or not the vehicle is on the relevant (∂V _OC / ∂T) curve. Here, the discharge capacity corresponding to the matched (∂V _OC / ∂T) curve is the required discharge capacity. Thus, the discharge capacity of the secondary battery 11 that is actually used can be estimated. In this way, (∂V _OC / ∂T) is measured and this value is used for estimation of the degree of deterioration, so that correction due to temperature for estimation of the degree of deterioration becomes unnecessary.

  Example 4 relates to a battery temperature estimation method and a battery temperature estimation apparatus according to the first and second aspects of the present disclosure.

When the measured charge / discharge current value of the secondary battery is I ₀ (charge: positive value, discharge: negative value) and the measured temperature value of the secondary battery is T ₀ , the amount of heat absorption / desorption ΔQ due to entropy change ₀ is given by the following equation (2). Here, E _emf is the electromotive force of the secondary battery.

ΔQ ₀ = −I ₀ · T ₀ · (∂E _emf / ∂T) (2)

The sum of the heat absorption amount ΔQ ₀ due to the entropy change and the heat generation amount I ₀ ² · r ₀ due to the internal resistance is the actual heat absorption amount. Therefore, based on the method described in the first embodiment, (基 づ き V _OC / ∂T) is obtained in advance, and the relative remaining capacity and (∂E _emf / 相 対 T) are further calculated from (∂V _OC / ∂T). Thus, it is possible to accurately predict temperature changes. Furthermore, in some cases, it is not necessary to measure the temperature of the secondary battery, which leads to a reduction in manufacturing cost of a large battery pack. In addition, in the state where the temperature fluctuation of the secondary battery is below the temperature measurement limit of the temperature measurement device and the open-circuit voltage fluctuation of the secondary battery is below the voltage measurement limit of the voltage measurement device, or the diffusion of lithium ions In the absence of reaction, E _emf = V _OC .

That is, the battery temperature estimation method of Example 4 is a battery temperature estimation method including a secondary battery or a lithium ion battery,
In the state where the temperature fluctuation of the battery is equal to or lower than the temperature measurement limit of the temperature measuring device 31 and the battery open-circuit voltage fluctuation is equal to or lower than the voltage measurement limit of the voltage measuring device 41 in advance [according to the first aspect of the present disclosure Battery Temperature Estimating Method] Alternatively, in the state where the lithium ion diffusion reaction has not occurred in advance [battery temperature estimating method according to the second aspect of the present disclosure], the voltage measuring device 41 causes the open circuit voltage V of the battery. _OC is measured, and the temperature T of the battery is measured by the temperature measuring device 31. Based on the open-circuit voltage measurement result and the temperature measurement result, the differential coefficient of the open-circuit voltage V _OC of the battery (∂ V _OC / ∂T) is obtained (for details, see Example 1),
Temperature measured value T ₀ of the battery, the charge and discharge current measured value I ₀ of the battery, and estimates the temperature of the battery based on the previously obtained (∂V _OC / ∂T).

Moreover, as shown in the conceptual diagram of FIG.
A voltage measuring device (voltage measuring circuit) 41 for measuring the open circuit voltage V _{OC of the} battery;
A current measuring device (current measuring circuit) 42 for measuring the charge / discharge current of the battery;
A temperature measuring device (temperature measuring circuit) 31 for measuring the temperature of the battery;
Temperature control devices 51, 52A, 52B for controlling the temperature of the battery, and
An arithmetic unit 21 for obtaining a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In the state where the temperature control device 51, 52A, 52B has previously set the battery temperature fluctuation below the temperature measurement limit of the temperature measurement device 31 and the battery open-circuit voltage fluctuation below the voltage measurement limit of the voltage measurement device 41. [Battery Temperature Estimating Device According to First Aspect of Present Disclosure] Alternatively, in a state where the lithium ion diffusion reaction has not been generated in advance by the temperature control devices 51, 52A and 52B [ Battery Temperature Estimating Device According to Second Embodiment], the battery open voltage V _OC is measured by the voltage measuring device 41, and the battery temperature T is measured by the temperature measuring device 31, and the open voltage measurement result and the temperature measurement are measured. Based on the result, (∂V _OC / ∂T) is obtained by the computing device 21, and the obtained (∂V _OC / ∂T) is stored in the computing device 21.
The computing device 21 further estimates the battery temperature based on the measured battery temperature value T ₀ , the stored (∂V _OC / ∂T), and the measured charge / discharge current value I ₀ of the battery.

The battery temperature estimation apparatus 10 of Example 4 also uses the temperature measurement apparatus 31 with a temperature measurement limit of 1 × 10 ⁻² ° C, and further has a voltage measurement limit of 1 × 10 ⁻⁶ volts. A voltage measuring device 41 is used. The configuration and structure of the battery temperature estimation device 10 of the fourth embodiment can be substantially the same as the configuration and structure of the battery (∂V _OC / ∂T) measurement device described in the first embodiment. Detailed description will be omitted.

Incidentally, the calorific value ΔQ per unit time of the secondary battery 11 is:
ΔQ = −I ₀ · T ₀ · (∂E _emf / ∂T) + I ₀ ² · r ₀ (3)
It can be expressed as

Accordingly, a relationship between the relative remaining capacity and (∂E _emf / ∂T) is obtained in advance based on (∂V _OC / ∂T), and this relationship is tabulated and stored in the arithmetic unit 21, for example. In addition, by calculating the relative remaining capacity dependency of the internal resistance value, the battery is based on the actually measured temperature value T ₀ of the actually used secondary battery and the measured charge / discharge current value I _0. Temperature can be estimated. By the way, when the current value I ₀ is large, it is necessary to measure the temperature dependence of the internal resistance value r _0. However, when the current value I ₀ is small, the temperature correction of the internal resistance value may be omitted. it can. The criterion is approximately 1C. For example, if the secondary battery is actually used in the form of a battery pack, the degree of heat dissipation of the secondary battery is determined depending on where the secondary battery is arranged in the battery pack. The heat dissipation degree of the secondary battery is analyzed in advance by a thermal fluid analysis program and calculated as an effective heat transfer amount X. The effective heat transfer amount X is a function of the battery temperature T. If the heat transfer amount X and the heat capacity of the secondary battery are known, the calorific value can be calculated from the measured current value I ₀ and the temperature T _{0 of the} secondary battery.

That is, the cumulative heat generation amount can be calculated by sequentially adding the product of the measurement time interval Δt of the current value I ₀ and the value of the heat generation amount ΔQ per unit time. Then, the temperature T _{calc of the} secondary battery can be calculated based on the following formula (4) using the effective heat transfer amount X, the heat capacity C _{hc of} the battery, and the measurement time interval Δt. The value of (∂E _emf / ∂T) is tabulated using the relative remaining capacity obtained by accumulating the current value I ₀ in the arithmetic unit 21 as a parameter (∂E _emf / ∂T). Can be obtained by searching.

T _calc = Σ [{− I ₀ · T ₀ · (∂E _emf / ∂T) + I ₀ ² · r ₀ −X} · (Δt / C _hp )]
(4)

  In the battery pack, for safety, it is necessary to measure the current of each secondary battery connected in series and measure the voltage of each secondary battery connected in parallel. In addition to this, when temperature sensors are attached to all the secondary batteries, the number of wires to the temperature sensor increases as the number of secondary batteries constituting the battery pack increases, and the communication load also increases. . However, in the fourth embodiment, since the temperature of the secondary battery constituting the battery pack can be estimated with high accuracy, the configuration of the battery pack is not complicated.

  Example 5 relates to a battery deterioration state prediction method and a battery deterioration state prediction apparatus according to the present disclosure.

After repeatedly charging and discharging the secondary battery several times, when measuring the voltage V _TV between the terminals with high accuracy in a state where the temperature of the secondary battery is adjusted with high accuracy, it is in accordance with the material system and individual differences of the secondary battery. It was found that the distortion of the discharge curve was observed. Therefore, by classifying the distortion of the discharge curve and associating the distortion of the discharge curve with the deterioration of the secondary battery, it is possible to predict how the secondary battery will deteriorate due to multiple charging and discharging. Is possible. Therefore, if the distortion of the discharge curve is obtained only once before incorporating the secondary battery into the product, the deterioration prediction accuracy of the secondary battery can be improved. That is, a charge / discharge process in which the temperature of the secondary battery is controlled with high accuracy and the voltage between terminals is measured at short time intervals (for example, the voltage between terminals is measured about 1000 times in one charge / discharge). Before the secondary battery is shipped or before the secondary battery is incorporated into the product, for example, the deterioration mode of the secondary battery is analyzed from the distortion of the discharge curve of the secondary battery obtained by repeating about 10 times. The lifetime of the secondary battery can be predicted from the result. In addition, it is possible to detect a defective secondary battery that deteriorates early.

That is, in the battery deterioration state prediction method of Example 5,
(A) The relationship between the terminal voltage and the relative remaining capacity at the time of discharging or charging is the relationship between the initial terminal voltage and the relative remaining capacity in a state where the temperature fluctuation of the battery is below the temperature measurement limit of the temperature measuring device 31. As a relationship, then
(B) Repeat charging / discharging of the battery a desired number of times, then
(C) In a state where the temperature fluctuation of the battery is not more than the temperature measurement limit of the temperature measuring device 31, the relationship between the inter-terminal voltage and the relative remaining capacity at the time of discharging or charging is as follows. The deterioration state of the battery is predicted based on the relationship between the initial inter-terminal voltage and the relative remaining capacity, and the relationship between the inter-terminal voltage after charging and discharging and the relative remaining capacity.

Moreover, as shown in the conceptual diagram of FIG.
A charge / discharge device for charging / discharging the battery,
A voltage measuring device (voltage measuring circuit) 41 for measuring a voltage between terminals of the battery;
A temperature measuring device 31 for measuring the temperature of the battery;
Temperature control devices 51, 52A, 52B for controlling the temperature of the battery, and
Arithmetic device 21,
With
(A) At the time of discharging or charging in a state where the temperature fluctuation of the battery is made not more than the temperature measurement limit of the temperature measuring device 31 by the temperature control devices 51, 52A, 52B (specifically, in the fifth embodiment, The relationship between the inter-terminal voltage and the relative remaining capacity during discharge) is obtained by the arithmetic unit 21 as the initial relationship between the terminal voltage and the relative remaining capacity,
(B) The charging / discharging device repeats charging / discharging of the battery a desired number of times,
(C) In a state where the temperature fluctuation of the battery is set to be equal to or lower than the temperature measurement limit of the temperature measuring device 31 by the temperature control devices 51, 52A, 52B, at the time of discharging or charging (specifically, in the fifth embodiment, The relationship between the inter-terminal voltage and the relative remaining capacity during discharge is determined by the arithmetic unit 21 as the relationship between the inter-terminal voltage after charging and discharging and the relative remaining capacity. Further, the initial inter-terminal voltage and the relative remaining capacity are obtained. Based on the relationship with the capacity, and the relationship between the inter-terminal voltage after charging and discharging and the relative remaining capacity, the computing device 21 predicts the deterioration state of the battery.

In the battery deterioration state prediction apparatus 10 of the fifth embodiment, the temperature measurement apparatus 31 having a temperature measurement limit of 1 × 10 ⁻² ° C. is used. Further, a voltage measuring device 41 having a voltage measurement limit of 1 × 10 ⁻⁶ volts is used. That is, in the above steps (a) and (c), the temperature control device 51, 52A, 52B causes the temperature fluctuation of the secondary battery 11 to be below the temperature measurement limit of the temperature measurement device 31, that is, 0.01 ° C. in a state of being less, 495. in other words, in a state where the temperature control of the secondary battery with high accuracy, voltage measurement limit is the inter-terminal voltage V _TV is measured at the time of discharging using a 1 micro-volts or less voltage measuring device 41 Is done. The configuration and structure of the battery deterioration state prediction device 10 of the fifth embodiment can be substantially the same configuration and structure as the battery (∂V _OC / ∂T) measurement device described in the first embodiment. Therefore, detailed description is omitted. Although the secondary battery 11 is connected to the charge / discharge device, the connection state of the secondary battery 11 to the charge / discharge device is not shown in FIG.

Specifically, for example, the discharge current is 0.5 C, and the measurement time interval of the inter-terminal voltage V _TV is 1 minute. Then, after such charge / discharge is repeated about 10 times, the relationship between the terminal voltage after charge / discharge and the relative remaining capacity (referred to as “post-charge / discharge curve” for convenience) is obtained. Here, the post-charge / discharge curve is usually the relationship between the initial terminal voltage (that is, obtained by the first measurement) and the relative remaining capacity (referred to as “initial / discharge curve” for convenience). In contrast, the discharge curve is shifted or distorted (see, for example, (A), (B), and (C) in FIG. 3). In normal secondary battery degradation, an increase in internal resistance and a decrease in discharge capacity result in a discharge curve as shown in FIG. 3A, 3B, and 3C, the dotted line indicates the initial / discharge curve, and the solid line indicates the post-charge / discharge / discharge curve. Such a difference between the initial / discharge curve and the post-charge / discharge curve is attributed to, for example, the material constituting the secondary battery. And since there are various deterioration factors such as a positive electrode, a negative electrode, and an electrolytic solution, not all secondary batteries are deteriorated in the same way. That is, as shown in FIG. 3B or FIG. 3C, there are differences between various initial / discharge curves and post-charge / discharge curves. In addition, if there is a factor that causes some short circuit, the sign appears in the difference between the initial / discharge curve and the post-charge / discharge curve. Therefore, it is considered that secondary batteries showing signs of deterioration such as (A), (B), and (C) in FIG. 3 will deteriorate as the deterioration modes of the respective secondary batteries progress. . That is, it is possible to make a life prediction of each secondary battery.

  Thus, the initial / discharge curve is obtained from the relationship between the initial inter-terminal voltage and the relative remaining capacity, and the post-charge / discharge curve is obtained from the relationship between the inter-terminal voltage after charge / discharge and the relative remaining capacity. The deterioration state of the secondary battery can be predicted based on the discharge curve and the post-charge / discharge / discharge curve. In addition, the initial / discharge curve and the post-charge / discharge curve are measured in a large number of secondary batteries, and the deterioration state of the large number of secondary batteries is investigated and correlated to obtain an initial / discharge curve and a charge / discharge curve. It is possible to grasp the relationship between the post-discharge / discharge curve and the deterioration state of the secondary battery, thereby predicting the deterioration state of the secondary battery based on the initial / discharge curve and the post-charge / discharge / discharge curve. it can.

When measuring the voltage V _TV between the terminals of the secondary battery with a voltage measurement accuracy of 1 millivolt in a thermostat with a temperature adjustment accuracy of about 0.1 ° C. as in the conventional method, several hundred times It has been found that defective products of secondary batteries cannot be identified without charging and discharging. On the other hand, in Example 5, the temperature of the secondary battery is adjusted with a temperature control means capable of high-speed response, such as a Peltier element, with an accuracy of 0.01 ° C. or less, and a voltage of 1 microvolt. By measuring the inter-terminal voltage V _TV with measurement accuracy, a slight change in the inter-terminal voltage V _TV can be captured. As a result, for example, it is possible to predict the deterioration state of the secondary battery in the future before factory shipment.

  When the secondary battery is actually used, if the temperature of the secondary battery can be controlled with a certain degree of accuracy during charging / discharging (specifically, for example, an accuracy of 0.1 ° C.) By measuring the voltage between terminals at a certain time interval (specifically, for example, every 10 minutes) with a certain degree of accuracy (specifically, for example, an accuracy of 0.1 millivolt) The progress of the deterioration state in the actual use of the secondary battery over a long period can be confirmed. In addition, if the time interval of the voltage measurement between terminals, the number of times of measurement, etc. are suitable for the deterioration mode analyzed in advance, the progress of the deterioration state of the secondary battery can be confirmed with high accuracy. If the structure can efficiently control the temperature of a plurality of secondary batteries arranged inside the battery pack, it is possible to predict the life of these secondary batteries arranged inside the battery pack. . In addition, when actually using a secondary battery, the magnitude and direction of the current flowing through the secondary battery changes. For this measurement, the current value is measured and the charge / discharge amount is constantly integrated. It is desirable to know the amount of current used. In applications where secondary batteries are used only under conditions corresponding to a part of the discharge curve, charging and discharging to measure the discharge curve when the secondary battery is not used may be performed. Good. When forming a battery pack from a plurality of secondary batteries, for example, secondary batteries showing the discharge curve of FIG. 3A are collected into a battery pack, or the secondary battery showing the discharge curve of FIG. The batteries may be collected into a battery pack, or the secondary batteries showing the discharge curve in FIG. 3C may be collected into a battery pack, or the discharge curves in FIGS. 3A, 3B, and 3C. The secondary battery indicating the above may be mixed as appropriate to form a battery pack.

Although the present disclosure has been described based on the preferred embodiments, the present disclosure is not limited to these embodiments. The configurations and structures of the battery (∂V _OC / ∂T) measuring device, the battery temperature estimating device, and the battery deterioration state predicting device in the examples are examples and can be changed as appropriate. In the embodiments, description has been made by taking a lithium ion battery as an example exclusively as a secondary battery, but the secondary battery is not limited to a lithium ion battery.

In addition, this indication can also take the following structures.
[1] << ( _VOC / ∂T) measuring method of battery: first embodiment >>
With the battery temperature fluctuation below the temperature measurement limit of the temperature measurement device and the battery open-circuit voltage fluctuation below the voltage measurement limit of the voltage measurement device, measure the open-circuit voltage of the battery with the voltage measurement device, and The temperature of the battery is measured by a temperature measuring device, and the differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the battery temperature T as a variable is obtained based on the open circuit voltage measurement result and the temperature measurement result. A method for measuring a differential coefficient of an open-circuit voltage with a temperature of a battery made of a secondary battery as a variable.
[2] << (∂V _OC / ∂T) measurement method of battery: second embodiment}
In the state where the lithium ion diffusion reaction has not occurred, the open circuit voltage of the battery is measured by the voltage measuring device, and the temperature of the battery is measured by the temperature measuring device. Based on the open voltage measurement result and the temperature measurement result, A method for measuring a differential coefficient of an open-circuit voltage using a temperature of a battery made of a lithium ion battery as a variable, which obtains a differential coefficient (の V _OC / ∂T) of the open-circuit voltage V _OC of the battery using the temperature T as a variable.
[3] The state in which the lithium ion diffusion reaction has not occurred is a state in which the battery temperature fluctuation is below the temperature measurement limit of the temperature measurement device, and the battery open-circuit voltage fluctuation is below the voltage measurement limit of the voltage measurement device. [2] A method for measuring a differential coefficient of an open-circuit voltage using a battery temperature as a variable.
[4] Any one of [1] to [3] using a voltage measuring device having a voltage measuring limit of 1 × 10 ⁻⁶ volts and a temperature measuring device having a temperature measuring limit of 1 × 10 ⁻² ° C. A method for measuring a differential coefficient of an open-circuit voltage using the battery temperature described in the section as a variable.
[5] Measurement of differential coefficient of open-circuit voltage using battery temperature as a variable according to any one of [1] to [4] to obtain (∂V _OC / ∂T) related to the relative remaining capacity of the battery Method.
[6] A method for measuring a differential coefficient of an open-circuit voltage using a battery temperature as a variable according to any one of [1] to [4], wherein (∂V _OC / ∂T) associated with a degree of battery deterioration is obtained. .
[7] << Battery Temperature Estimation Method: First Aspect >>
In advance, measure the open circuit voltage of the battery with the voltage measurement device in a state where the temperature variation of the battery is below the temperature measurement limit of the temperature measurement device and the open circuit voltage variation of the battery is below the voltage measurement limit of the voltage measurement device. The battery temperature is measured by a temperature measuring device, and the differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC using the battery temperature T as a variable based on the open circuit voltage measurement result and the temperature measurement result. Seeking
A battery temperature estimation method comprising a secondary battery, wherein the battery temperature is estimated based on the battery temperature measurement value, the battery charge / discharge current measurement value, and (∂V _OC / ∂T) obtained in advance.
[8] <Battery temperature estimation method: second embodiment>
In the state where the diffusion reaction of lithium ions has not occurred in advance, the open circuit voltage of the battery is measured by the voltage measuring device, and the temperature of the battery is measured by the temperature measuring device, based on the open voltage measurement result and the temperature measurement result, _Obtain the differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable,
A battery temperature estimation method comprising a lithium ion battery, wherein the battery temperature is estimated based on a measured battery temperature value, a measured charge / discharge current value of the battery, and (∂V _OC / ∂T) obtained in advance.
[9] << Method for predicting battery deterioration state >>
(A) The relationship between the voltage between terminals and the relative remaining capacity during discharging or charging in the state where the temperature fluctuation of the battery is below the temperature measurement limit of the temperature measuring device, and the relationship between the initial terminal voltage and the relative remaining capacity Sought as, then
(B) Repeat charging / discharging of the battery a desired number of times, then
(C) In a state where the temperature fluctuation of the battery is not more than the temperature measurement limit of the temperature measuring device, the relationship between the inter-terminal voltage during discharging or charging and the relative remaining capacity is as follows: It consists of a secondary battery that predicts the deterioration state of the battery based on the relationship between the initial terminal voltage and the relative remaining capacity and the relationship between the terminal voltage after charging and discharging and the relative remaining capacity. A battery deterioration state prediction method.
[10] The battery deterioration state prediction method according to [9], wherein a temperature measurement device having a temperature measurement limit of 1 × 10 ⁻² ° C is used.
[11] The battery deterioration state prediction method according to [9] or [10], in which a voltage between terminals is measured using a voltage measuring device having a voltage measurement limit of 1 × 10 ⁻⁶ volts.
[12] The initial / discharge curve is obtained from the relationship between the initial inter-terminal voltage and the relative remaining capacity, and the post-charge / discharge curve is obtained from the relationship between the inter-terminal voltage after charge / discharge and the relative remaining capacity. The battery deterioration state prediction method according to any one of [9] to [11], wherein the deterioration state of the battery is predicted based on the curve and the post-charge / discharge / discharge curve.
[13] << Battery (∂V _OC / ∂T) Measuring Device: First Mode >>
A voltage measuring device for measuring the open-circuit voltage of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
With the temperature control device, the battery temperature fluctuation is less than or equal to the temperature measurement limit of the temperature measurement device, and the battery open-circuit voltage fluctuation is less than or equal to the voltage measurement limit of the voltage measurement device. Is measured, and the temperature of the battery is measured by the temperature measuring device, and (∂V _OC / ∂T) is obtained by the arithmetic device based on the open circuit voltage measurement result and the temperature measurement result. A device for measuring the differential coefficient of open-circuit voltage with temperature as a variable.
[14] << Battery (∂V _OC / ∂T) Measuring Device: Second Mode >>
A voltage measuring device for measuring the open-circuit voltage of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In a state in which the lithium ion diffusion reaction has not occurred, the voltage control device measures the open circuit voltage of the battery, and the temperature measurement device measures the battery temperature. A device for measuring a differential coefficient of an open-circuit voltage, in which (∂V _OC / ∂T) is obtained by an arithmetic device based on a temperature measurement result, with a temperature of a battery made of a lithium ion battery as a variable.
[15] <Battery temperature estimation device: first embodiment>
A voltage measuring device for measuring the open-circuit voltage of the battery,
A current measuring device for measuring the charge / discharge current of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In advance, with the temperature control device, the battery temperature fluctuation is less than the temperature measurement limit of the temperature measurement device, and the battery open-circuit voltage fluctuation is less than the voltage measurement limit of the voltage measurement device. The open-circuit voltage is measured, and the temperature of the battery is measured by the temperature measuring device. Based on the open-circuit voltage measurement result and the temperature measurement result, (演算 V _OC /） T) is obtained by the arithmetic device and is obtained (∂ V _OC / ∂T) is stored in the arithmetic unit,
The computing device further estimates the temperature of the battery based on the measured value of the battery temperature, the stored (∂V _OC / ∂T), and the measured value of the charge / discharge current of the battery. Estimating device.
[16] <Battery temperature estimation device: second embodiment>
A voltage measuring device for measuring the open-circuit voltage of the battery,
A current measuring device for measuring the charge / discharge current of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In a state in which the lithium ion diffusion reaction has not occurred in advance, the open circuit voltage of the battery is measured by the voltage measuring device and the open circuit voltage is measured by the temperature measuring device. Based on the result and the temperature measurement result, (演算 V _OC / ∂T) is obtained by the computing device, and the obtained (∂V _OC / ∂T) is stored in the computing device,
The computing device further estimates the battery temperature based on the measured battery temperature value, the stored (∂V _OC / T), and the measured charge / discharge current value of the battery. Estimating device.
[17] << Battery degradation state prediction apparatus >>
A charging / discharging device for charging / discharging the battery,
A voltage measuring device for measuring the voltage between the terminals of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
Arithmetic unit,
With
The relationship between the terminal voltage and the relative remaining capacity during discharging or charging is the initial terminal voltage and the relative remaining capacity when the battery temperature fluctuation is below the temperature measurement limit of the temperature measuring device by the temperature controller. Is calculated by the arithmetic unit as
The charging / discharging device repeats charging / discharging of the battery a desired number of times,
In a state where the temperature fluctuation of the battery is not more than the temperature measurement limit of the temperature measurement device by the temperature control device, the relationship between the voltage between the terminals at the time of discharging or charging and the relative remaining capacity is relative to the voltage between the terminals after charging and discharging. The relationship with the remaining capacity is determined by the arithmetic device, and further based on the relationship between the initial inter-terminal voltage and the relative remaining capacity, and the relationship between the inter-terminal voltage after charging and discharging and the relative remaining capacity, by the arithmetic device. A battery deterioration state prediction device comprising a secondary battery, in which a battery deterioration state is predicted.

10 ... (∂V _OC / ∂T) measuring device, battery temperature estimating device, battery deterioration state predicting device, 11 ... secondary battery or lithium ion battery, 21 ... computing device, 22 ... Memory, 23 ... Voltage / temperature memory, 31 ... Temperature measuring device (temperature measuring circuit), 32 ... Temperature measuring unit, 33, 43A, 43B, 53A, 53B ... Wiring, 41 ... Voltage measuring device (voltage measuring circuit), 42 ... Current measuring device (current measuring circuit), 51 ... Temperature controller, 52A, 52B ... Peltier element, 61A, 61B ... Container, 62A , 62B ... contact terminal portion

Claims (17)

With the battery temperature fluctuation below the temperature measurement limit of the temperature measurement device and the battery open-circuit voltage fluctuation below the voltage measurement limit of the voltage measurement device, measure the open-circuit voltage of the battery with the voltage measurement device, and The temperature of the battery is measured by a temperature measuring device, and the differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the battery temperature T as a variable is obtained based on the open circuit voltage measurement result and the temperature measurement result. A method for measuring a differential coefficient of an open-circuit voltage with a temperature of a battery made of a secondary battery as a variable. In the state where the lithium ion diffusion reaction has not occurred, the open circuit voltage of the battery is measured by the voltage measuring device, and the temperature of the battery is measured by the temperature measuring device. Based on the open voltage measurement result and the temperature measurement result, A method for measuring a differential coefficient of an open-circuit voltage using a temperature of a battery made of a lithium ion battery as a variable, which obtains a differential coefficient (の V _OC / ∂T) of the open-circuit voltage V _OC of the battery using the temperature T as a variable.   The state in which the lithium ion diffusion reaction has not occurred is a state in which the temperature fluctuation of the battery is less than or equal to the temperature measurement limit of the temperature measurement device, and the battery open-circuit voltage fluctuation is less than or equal to the voltage measurement limit of the voltage measurement device. Item 3. A method for measuring a differential coefficient of an open-circuit voltage using the battery temperature described in Item 2 as a variable. 3. The temperature of the battery according to claim 1 or ² , wherein a voltage measuring device having a voltage measuring limit of 1 × 10 ⁻⁶ volts and a temperature measuring device having a temperature measuring limit of 1 × 10 ⁻² ° C. are used. A method for measuring the differential coefficient of open circuit voltage as a variable. The method for measuring a differential coefficient of an open-circuit voltage using a battery temperature as a variable according to claim 1 or 2, wherein (∂V _OC / ∂T) related to a relative remaining capacity of the battery is obtained. The method for measuring a differential coefficient of an open-circuit voltage using a battery temperature as a variable according to claim 1 or 2, wherein (∂V _OC / ∂T) related to a degree of deterioration of the battery is obtained. In advance, measure the open circuit voltage of the battery with the voltage measurement device in a state where the temperature variation of the battery is below the temperature measurement limit of the temperature measurement device and the open circuit voltage variation of the battery is below the voltage measurement limit of the voltage measurement device. The battery temperature is measured by a temperature measuring device, and the differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC using the battery temperature T as a variable based on the open circuit voltage measurement result and the temperature measurement result. Seeking
A battery temperature estimation method comprising a secondary battery, wherein the battery temperature is estimated based on the battery temperature measurement value, the battery charge / discharge current measurement value, and (∂V _OC / ∂T) obtained in advance. In the state where the diffusion reaction of lithium ions has not occurred in advance, the open circuit voltage of the battery is measured by the voltage measuring device, and the temperature of the battery is measured by the temperature measuring device, based on the open voltage measurement result and the temperature measurement result, _Obtain the differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable,
A battery temperature estimation method comprising a lithium ion battery, wherein the battery temperature is estimated based on a measured battery temperature value, a measured charge / discharge current value of the battery, and (∂V _OC / ∂T) obtained in advance. (A) The relationship between the voltage between terminals and the relative remaining capacity during discharging or charging in the state where the temperature fluctuation of the battery is below the temperature measurement limit of the temperature measuring device, and the relationship between the initial terminal voltage and the relative remaining capacity Sought as, then
(B) Repeat charging / discharging of the battery a desired number of times, then
(C) In a state where the temperature fluctuation of the battery is not more than the temperature measurement limit of the temperature measuring device, the relationship between the inter-terminal voltage during discharging or charging and the relative remaining capacity is as follows: It consists of a secondary battery that predicts the deterioration state of the battery based on the relationship between the initial terminal voltage and the relative remaining capacity and the relationship between the terminal voltage after charging and discharging and the relative remaining capacity. A battery deterioration state prediction method. The method for predicting a deterioration state of a battery according to claim 9, wherein a temperature measuring device having a temperature measurement limit of 1 × 10 ⁻² ° C is used. The battery deterioration state prediction method according to claim 9, wherein the voltage between terminals is measured using a voltage measuring device having a voltage measurement limit of 1 × 10 ⁻⁶ volts.   Obtain the initial / discharge curve from the relationship between the initial terminal voltage and the relative remaining capacity, and obtain the post-charge / discharge curve from the relationship between the terminal voltage after charge / discharge and the relative remaining capacity. The battery deterioration state prediction method according to claim 9, wherein the deterioration state of the battery is predicted based on a post-discharge / discharge curve. A voltage measuring device for measuring the open-circuit voltage of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
With the temperature control device, the battery temperature fluctuation is less than or equal to the temperature measurement limit of the temperature measurement device, and the battery open-circuit voltage fluctuation is less than or equal to the voltage measurement limit of the voltage measurement device. Is measured, and the temperature of the battery is measured by the temperature measuring device, and (∂V _OC / ∂T) is obtained by the arithmetic device based on the open circuit voltage measurement result and the temperature measurement result. A device for measuring the differential coefficient of open-circuit voltage with temperature as a variable. A voltage measuring device for measuring the open-circuit voltage of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In a state in which the lithium ion diffusion reaction has not occurred, the voltage control device measures the open circuit voltage of the battery, and the temperature measurement device measures the battery temperature. A device for measuring a differential coefficient of an open-circuit voltage, in which (∂V _OC / ∂T) is obtained by an arithmetic device based on a temperature measurement result, with a temperature of a battery made of a lithium ion battery as a variable. A voltage measuring device for measuring the open-circuit voltage of the battery,
A current measuring device for measuring the charge / discharge current of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In advance, with the temperature control device, the battery temperature fluctuation is less than the temperature measurement limit of the temperature measurement device, and the battery open-circuit voltage fluctuation is less than the voltage measurement limit of the voltage measurement device. The open-circuit voltage is measured, and the temperature of the battery is measured by the temperature measuring device. Based on the open-circuit voltage measurement result and the temperature measurement result, (演算 V _OC /） T) is obtained by the arithmetic device and is obtained (∂ V _OC / ∂T) is stored in the arithmetic unit,
The computing device further estimates the temperature of the battery based on the measured value of the battery temperature, the stored (∂V _OC / ∂T), and the measured value of the charge / discharge current of the battery. Estimating device. A voltage measuring device for measuring the open-circuit voltage of the battery,
A current measuring device for measuring the charge / discharge current of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
An arithmetic unit for calculating a differential coefficient (∂V _OC / ∂T) of the open circuit voltage V _OC of the battery with the temperature T of the battery as a variable;
With
In a state in which the lithium ion diffusion reaction has not occurred in advance, the open circuit voltage of the battery is measured by the voltage measuring device and the open circuit voltage is measured by the temperature measuring device. Based on the result and the temperature measurement result, (演算 V _OC / ∂T) is obtained by the computing device, and the obtained (∂V _OC / ∂T) is stored in the computing device,
The computing device further estimates the battery temperature based on the measured battery temperature value, the stored (∂V _OC / T), and the measured charge / discharge current value of the battery. Estimating device. A charging / discharging device for charging / discharging the battery,
A voltage measuring device for measuring the voltage between the terminals of the battery,
A temperature measuring device for measuring the temperature of the battery,
A temperature control device for controlling the temperature of the battery; and
Arithmetic unit,
With
The relationship between the terminal voltage and the relative remaining capacity during discharging or charging is the initial terminal voltage and the relative remaining capacity when the battery temperature fluctuation is below the temperature measurement limit of the temperature measuring device by the temperature controller. Is calculated by the arithmetic unit as
The charging / discharging device repeats charging / discharging of the battery a desired number of times,
In a state where the temperature fluctuation of the battery is not more than the temperature measurement limit of the temperature measurement device by the temperature control device, the relationship between the terminal voltage at the time of discharging or charging and the relative remaining capacity is relative to the terminal voltage after charging / discharging. The relationship with the remaining capacity is determined by the arithmetic device, and further based on the relationship between the initial inter-terminal voltage and the relative remaining capacity, and the relationship between the inter-terminal voltage after charging and discharging and the relative remaining capacity, by the arithmetic device. A battery deterioration state prediction device comprising a secondary battery, in which a battery deterioration state is predicted.

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