WO2021220886A1 - Evaluating device, evaluating method, and program for metal-air battery - Google Patents

Abstract

Provided are an evaluating device, an evaluating method, and a program for continuously and automatically evaluating the battery characteristics of a metal-air battery. This evaluating device for evaluating the battery characteristics of a metal-air battery is provided with a weight measuring unit for measuring weight, a raising and lowering unit which is provided with a stage that is raised and lowered, a housing accommodating at least the weight measuring unit and the metal-air battery, a charge/discharge characteristic measuring unit for measuring charge/discharge characteristics, and a control unit which evaluates the battery characteristics by controlling the operations of the raising and lowering unit, the weight measuring unit, and the charge/discharge characteristic measuring unit, wherein the control unit is provided with a measurement control unit which causes the stage of the raising and lowering unit to be raised and lowered, and which executes measurements by means of the weight measuring unit and the charge/discharge characteristic measuring unit to acquire an amount of change in weight and the charge/discharge characteristics, and a calculating/evaluating unit which calculates and evaluates the battery characteristics on the basis of the change in weight and the charge/discharge characteristics.

Description

Evaluation equipment, evaluation methods, and programs for metal-air batteries

The present invention relates to an evaluation device, an evaluation method, and a program for continuously and automatically evaluating the battery characteristics of a metal-air battery.

In recent years, due to the spread of renewable energy and the demand for electrification of automobiles, the development of a storage battery that is lightweight and has a large capacity, that is, has a higher energy density is required. Among the secondary batteries that can be realized, the lithium-air battery has the highest theoretical energy density, and can achieve an energy density that greatly exceeds that of the lithium-ion battery currently in widespread use.

Lithium-air batteries use lithium metal as the negative electrode active material and atmospheric oxygen as the positive electrode active material. During discharge of the lithium metal anode is eluted (Li⇔Li ^{+ +} e ^-), lithium peroxide reacts with the absorbed oxygen from the atmosphere at the positive electrode is deposited _{^{(2Li + + 2e - + O}} 2 ⇔Li 2 O 2). At the time of charging, the opposite reaction occurs, and these are repeated to charge and discharge. Here, the positive electrode is also called an air electrode because it is an electrode having a function of absorbing and discharging atmospheric oxygen in accordance with charging and discharging.

In order to improve the charge / discharge cycle characteristics of the lithium-air battery cell, it is necessary to create a situation in which the above-mentioned electrochemical reaction at the air electrode proceeds reversibly with an efficiency of almost 100%. Therefore, it is necessary to accurately measure and determine the "efficiency" of these battery reactions, but these methods are limited and often lack accuracy and reliability, and reflect the environment in which the cell is actually charged and discharged. Often not something to do.

Cell reaction at the air electrode _{^{(2Li + + 2e - + O}} 2 ⇔Li 2 O 2) as a method of estimating the efficiency, at present 1. _{A method for quantifying Li 2} O ₂ that precipitates and decomposes on the air electrode by titration, and 2. A method for quantifying oxygen gas absorbed and discharged into a cell has been devised and widely studied.

However, 1. _{The amount of Li 2} O ₂ detected by the above method is less than 90% of the amount estimated to be generated from the amount of discharge or charge, and the generated Li ₂ O ₂ cannot be completely supplemented. Alternatively, it is not clear whether charging / discharging is actually proceeding with a battery reaction efficiency of 90% or less. Further, since it is necessary to prepare a plurality of cells having different discharge / charge states and individually disassemble and titrate the cells, the workability is low and the variation due to individual differences is large (see, for example, Non-Patent Document 1).

2. The method of quantifying the oxygen absorbed and discharged into the cell is performed by measuring the oxygen partial pressure that decreases by discharging the cell in a closed housing. At the time of charging, the housing is replaced with an inert gas, the cell is charged, and all the discharged oxygen is recovered and weighed. Since the pressure fluctuates according to the discharge / charge state, there is a problem that the measurement does not reflect the actual cell environment, for example, the atmospheric environment (see, for example, Non-Patent Document 1). In addition, it is difficult to track the reaction efficiency of multiple cycles because it is necessary to replace the gas and switch the measurement method according to the switching between discharging and charging.

On the other hand, recently, the development of electrolytes and electrode materials for lithium-air battery cells has progressed, and the capacity and number of cycles that can be discharged and charged are increasing. In line with this, it is necessary to establish a measurement method that can accurately and easily evaluate the battery reaction efficiency in long-term, multi-cycle charge / discharge operation (see, for example, Non-Patent Document 2).

In addition, cells that have a wider electrode area and laminated structure than basic battery reaction test applications and are designed to take a large current have also been developed. It is necessary to develop a method for measuring how much the electrolytic solution volatilizes through the air holes in an atmospheric environment or an oxygen flow environment (see, for example, Non-Patent Document 3). In the atmospheric environment, it is necessary to investigate how much the cell absorbs impurity gases such as water and carbon dioxide contained in the atmosphere that are not involved in the normal battery reaction.

Among them, the mass of the cell is the focus of attention. Lithium-air battery cells absorb and discharge oxygen by discharging and charging, which causes the weight to change little by little. The battery reaction efficiency can be estimated by measuring the amount of oxygen fixed in the cell from the discharge / charge capacity of the cell and the amount of weight change. In addition, the amount of volatilization of the electrolytic solution can be estimated from a slight change in cell weight when there is no current (during rest). However, since the weight of a stationary cell cannot be continuously weighed for a long period of time, the cell weight before and after discharge / charge or after a certain period of time is compared and estimated one by one.

From the above, an object of the present invention is to provide an evaluation device for continuously and automatically evaluating the battery characteristics of a metal-air battery, a method thereof, and a program thereof.

The evaluation device for evaluating the battery characteristics of the metal air battery of the present invention includes a weight measuring unit for measuring the weight of the metal air battery and a stage for mounting the metal air battery, and raises and lowers the stage. A unit, a housing accommodating at least the weight measuring unit and the metal air battery, a charge / discharge characteristic measuring unit for measuring the charge / discharge characteristics of the metal air battery, an elevating unit, the weight measuring unit, and the charging unit. A control unit that controls the operation with the discharge characteristic measuring unit and evaluates the battery characteristics of the metal air battery is provided, and the control unit raises and lowers the stage of the elevating unit to raise and lower the weight measuring unit and the charging / discharging unit. Based on the measurement control unit that executes the measurement by the characteristic measurement unit and acquires the weight change amount and charge / discharge characteristics of the metal air battery, and the weight change amount and the charge / discharge characteristics acquired by the measurement control unit. It is provided with a calculation / evaluation unit that calculates / evaluates the battery characteristics of the metal air battery, thereby solving the above-mentioned problems.
The calculating and evaluation unit, the change in weight at time _{t r} during rest of the charge and discharge characteristics Wt _r and time _{t r0 (However, t r>} t _r0) weight change amount difference Wt of the change in weight _{Wt r0} of dividing the _r -wt _r0 by the time difference _t r _{-t r0,} electrolyte evaporation rate _{((Wt r -Wt r0) /} (t r -t r0)) further comprise an electrolyte solution evaporation rate calculation unit for calculating a good.
The calculation / evaluation unit estimates the volatilization of the electrolytic solution at the _{time t d from the amount of change in weight at the time t d} during the discharge of the charge / discharge characteristics using the volatilization rate of the electrolytic solution in the rest immediately before the discharge. A discharge weight change amount calculation unit may be further provided, which reduces the amount and calculates the weight change amount due only to the discharge reaction.
The calculation / evaluation unit divides the amount of weight change due only to the discharge reaction _{of the time interval Δt d} during discharge of the charge / discharge characteristics calculated by the discharge weight change amount calculation unit by the _{time interval Δt d.} , The number of reaction electrons for calculating the weight change rate, dividing the current value used for measuring the charge / discharge characteristics by the weight change rate, and calculating the number of electrons reacting with the air absorbed in the metal air battery. A calculation unit may be further provided.
The calculation / evaluation unit estimates the volatilization of the electrolyte at _{time t c from the amount of change in weight at time t c} during charging of the charge / discharge characteristics using the volatilization rate of the electrolyte in the rest immediately before charging. A charge weight change amount calculation unit may be further provided, which reduces the amount and calculates the weight change amount due only to the charge reaction.
The calculation / evaluation unit divides the amount of weight change due only to the charging reaction _{of the time interval Δt c} during charging of the charge / discharge characteristics calculated by the charge weight change amount calculation unit by the _{time interval Δt c.} , The reaction to calculate the weight change rate, divide the current value used for measuring the charge / discharge characteristics by the weight change rate, and calculate the number of electrons required to discharge the air fixed to the metal-air battery. An electron number calculation unit may be further provided.
The calculation / calculation unit calculates the capacitance from the time ΔT required for the weight change to occur after the start of discharge of the charge / discharge characteristics and the current value flowing during the time ΔT. May be further provided.
The control unit may further include a display unit that displays the result of the calculation / evaluation unit.
A temperature detection unit may be further provided in the housing.
An atmospheric pressure detection unit may be further provided in the housing.
The control unit may further include a weighing value correction unit that corrects the weighing value by the weight measuring unit with the sensitivity drift value of the weight measuring unit.
The housing may include a gas air supply port and a gas exhaust port.
A temperature control device for holding the temperature inside the housing may be further provided.
In the method for evaluating the battery characteristics of the metal air battery of the present invention, the arrangement of the metal air battery at the measurement position of the weight measuring unit and the separation of the metal air battery from the measurement position are repeated, and the metal air battery is evaluated. The charge / discharge characteristics of the metal air battery are measured at the same time as the repeated measurement of the weight, the weight change amount obtained by the repeated measurement, and the charge / discharge. It includes calculating and evaluating the battery characteristics of the metal air battery based on the charge / discharge characteristics obtained by measuring the characteristics, thereby solving the above-mentioned problems.
The calculation and evaluation that is, the change in weight at time _{t r} during rest of the charge and discharge characteristics Wt _r and time _{t r0 (However, t r>} t _r0) the change in weight difference between the change in weight _{Wt r0} of dividing the Wt _r -wt _r0 by the time difference _t r _{-t r0,} may further include calculating the electrolyte volatilization rate _{((Wt r -Wt r0) /} (t r -t r0)).
The calculation / evaluation is an electrolytic solution at the _{time t d estimated from the amount of change in weight at the time t d} during the discharge of the charge / discharge characteristics and the volatilization rate of the electrolytic solution in the rest immediately before the discharge. It may further include reducing the amount of volatilization and calculating the amount of weight change due only to the discharge reaction.
The calculation / evaluation is to calculate the weight change rate by dividing the amount of weight change caused only by the discharge reaction _{of the time interval Δt d} during discharge of the calculated charge / discharge characteristics by the _{time interval Δt d.} Then, the current value used for measuring the charge / discharge characteristics may be divided by the weight change rate to calculate the number of electrons reacting with the air absorbed by the metal air battery.
The calculation / evaluation is an electrolytic solution at the _{time t c estimated from the amount of change in weight at the time t c} during charging of the charge / discharge characteristics using the electrolytic solution volatilization rate in the rest immediately before the charge. It may further include reducing the amount of volatilization and calculating the amount of weight change due only to the charging reaction.
The calculation / evaluation is to calculate the weight change rate by dividing the amount of weight change caused only by the charging reaction _{of the time interval Δt c} during charging of the calculated charge / discharge characteristics by the _{time interval Δt c.} Further, it may further include calculating the number of electrons required for discharging the air fixed to the metal-air battery by dividing the current value used for measuring the charge / discharge characteristics by the weight change rate. good.
The calculation / evaluation further includes calculating the capacitance from the time ΔT required for the weight change to occur after the start of discharge of the charge / discharge characteristics and the current value flowing during the time ΔT. You may.
Prior to the repeated measurement, the placement of the immutable weight product at the measurement position of the weight measuring unit and the separation of the immutable weight product from the measurement position are repeated, and the weight of the immutable weight product is repeatedly measured. At the same time as the repeated measurement of the weight of the immutable weight product, the temperature change and / or the atmospheric pressure change in the measurement environment is measured, and the weighed value of the immutable weight product is the temperature change and / or. In determining whether or not it is fluctuating due to the change in atmospheric pressure, and when it is determined in the determination that it is fluctuating, the weighing value is corrected by the sensitivity drift value of the weight measuring unit, and the determination is made. If it is determined that there is no fluctuation, it may further include not correcting the weighing value.
Prior to the repeated measurement, the flow of the atmosphere control gas in the measurement environment may be further included.
The program for evaluating the battery characteristics of the metal air battery of the present invention repeats the arrangement of the metal air battery at the measurement position of the weight measuring unit and the separation of the metal air battery from the measurement position, and the metal air battery. The function of repeatedly measuring the weight of the metal, the function of measuring the charge / discharge characteristics of the metal air battery at the same time as the repeated measurement of the weight, the amount of change in weight obtained by the repeated measurement, and the charge / discharge. Based on the charge / discharge characteristics obtained by measuring the characteristics, the computer is realized with a function of calculating and evaluating the battery characteristics of the metal air battery, thereby solving the above-mentioned problems.
The calculation and evaluation functions, the change in weight at time _{t r} during rest of the charge and discharge characteristics Wt _r and time _{t r0 (However, t r>} t _r0) the change in weight difference between the change in weight _{Wt r0} of dividing the Wt _r -wt _r0 by the time difference _t r _{-t r0,} electrolyte evaporation rate _{((Wt r -Wt r0) /} (t r -t r0)) may further comprise a function of calculating the.
The function of calculating and evaluating the electrolytic solution at the _{time t d estimated from the amount of change in the weight of the electrolytic solution at the time t d} during the discharge of the charge / discharge characteristics using the volatilization rate of the electrolytic solution in the rest immediately before the discharge. It may further include a function of reducing the amount of volatilization and calculating the amount of weight change due only to the discharge reaction.
The calculation / evaluation function calculates the weight change rate by dividing the amount of weight change caused only by the discharge reaction _{of the time interval Δt d} during discharge of the calculated charge / discharge characteristics by the _{time interval Δt d.} Then, the function of dividing the current value used for measuring the charge / discharge characteristics by the weight change rate and calculating the number of electrons reacting with the air absorbed by the metal air battery may be further included.
The function of calculating and evaluating the electrolytic solution at the _{time t c estimated from the amount of change in weight at the time t c} during charging of the charge / discharge characteristics using the electrolytic solution volatilization rate in the rest immediately before the charge. It may further include a function of reducing the amount of volatilization and calculating the amount of weight change due only to the charging reaction.
The calculation / evaluation function calculates the weight change rate by dividing the amount of weight change caused only by the charging reaction _{of the time interval Δt c} during charging of the calculated charge / discharge characteristics by the _{time interval Δt c.} Then, the function of dividing the current value used for measuring the charge / discharge characteristics by the weight change rate and calculating the number of electrons required for discharging the air fixed to the metal-air battery may be further included.
The function of calculating and evaluating further includes a function of calculating the capacitance from the time ΔT required for the weight change to occur after the start of discharging the charge / discharge characteristics and the current value flowing during the time ΔT. It may be.

As described above, the evaluation device for evaluating the battery characteristics of the metal-air battery of the present invention is provided with an elevating part, and the zero point correction of the weight measuring part is performed every time measurement is performed. As a result, the weight change of the metal-air battery can be continuously and accurately measured over a long period of time. Further, since the weight change measurement by the weight measuring unit and the charge / discharge measurement by the charge / discharge characteristic measurement unit are performed at the same time, the charge / discharge process of the metal air battery is based on the results of the weight change amount and the charge / discharge characteristics. The volatilization rate of electrolyte, the amount of weight change due to discharge or charging reaction, the number of electrons required for absorption or discharge of air (oxygen), capacitance, etc. can be calculated, and the performance evaluation of metal air batteries is continuously high for a long period of time. It can be carried out with high accuracy.

In the method for evaluating a metal-air battery of the present invention, the weight of the metal-air battery is repeatedly measured, and at the same time, the charge / discharge characteristics are measured, and the battery characteristics of the metal-air battery are determined based on the obtained weight change amount and charge / discharge characteristics. evaluate. Since various battery characteristics are evaluated based on the amount of change in weight over time, which is zero-point corrected each time the weight is measured, and the charge / discharge characteristics over time associated with this, the performance evaluation of the metal-air battery is lengthened. It can be carried out continuously and with high accuracy over a period of time. The present invention also provides a program in which a computer executes such a function.

Schematic diagram showing the evaluation apparatus of the present invention A block diagram showing a configuration of a control unit of the evaluation device of the present invention. Diagram showing an exemplary graphical user interface (GUI) screen The figure which shows the exemplary weight measurement condition setting screen. Diagram showing exemplary weight measurement results The figure which shows another example weight measurement condition setting screen. Figure showing another exemplary weight measurement result The figure which shows the example charge / discharge characteristic measurement condition setting screen. Diagram showing an exemplary evaluation item setting screen Show exemplary results Diagram showing another exemplary result A flowchart showing a method for evaluating the battery characteristics of the metal-air battery of the present invention. A flowchart showing a method for evaluating the battery characteristics of another metal-air battery of the present invention. The figure which shows the charge / discharge characteristic measurement condition setting screen of Example 1. The figure which shows the weight change amount and charge / discharge characteristics of the lithium ion battery of Example 1. The figure which shows the weight change amount and the temperature change of the lithium ion battery of Example 1. The figure which shows the weight change amount and the temperature change of the lithium ion battery of Example 2. The figure which shows the charge / discharge characteristic measurement condition setting screen of Example 3. The figure which shows the result of the battery characteristic of the lithium-air battery of Example 3. The figure which shows another result of the battery characteristic of the lithium-air battery of Example 3. The figure which shows the weight measurement condition setting screen of Example 4. The figure which shows the result of the battery characteristic of the lithium-air battery of Example 4. The figure which shows another result of the battery characteristic of the lithium-air battery of Example 4. The figure which shows another result of the battery characteristic of the lithium-air battery of Example 4. The figure which shows another result of the battery characteristic of the lithium-air battery of Example 4.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same elements are given the same numbers, and the description thereof will be omitted.

FIG. 1 is a schematic view showing the evaluation device of the present invention.

The evaluation device 100 of the present invention measures the battery characteristics of a metal-air battery. Here, the target metal-air battery is a metal battery that exchanges with an external gas such as a lithium air battery, a lithium carbon dioxide battery, a sodium air battery, an air zinc battery, an air iron battery, an air aluminum battery, and an air magnesium battery. be. In the following description, for the sake of simplicity, a lithium-air battery will be used as the metal-air battery, and the case where the external gas is oxygen will be described. In the specification of the present application, external gases may be collectively referred to as air.

The evaluation device 100 of the present invention includes a weight measuring unit 110 for measuring the weight of a metal-air battery (shown as a cell in FIG. 1) and a stage 120 for mounting the metal-air battery, and raises and lowers the stage 120. The elevating unit 130, the housing 140 accommodating at least the weight measuring unit 110 and the metal-air battery, the charge / discharge characteristic measuring unit 150 for measuring the charge / discharge characteristics of the metal-air battery, and the elevating unit 130 and the weight measuring unit 110. It includes a control unit 160 that controls the operation with the charge / discharge characteristic measurement unit 150 and evaluates the battery characteristics of the metal-air battery.

With such a configuration, the evaluation device 100 of the present invention accurately measures the weight change of the metal-air battery over a long period of time, simultaneously measures the weight measurement and the charge / discharge measurement of the metal-air battery, and obtains the results. Since it is stored in association with each other, it is possible to calculate the electrolyte volatilization rate associated with the charge / discharge reaction of the metal-air battery, the amount of weight change due to charge / discharge, the number of electrons due to the reaction / discharge of air, the capacitance, etc. Performance evaluation can be performed with high accuracy over a long period of time. Hereinafter, each component will be described in detail.

The weight measuring unit 110 is not particularly limited as long as it can measure the weight of the metal-air battery, but an electronic balance is an example. Although the weight measuring unit 110 is connected to the control unit 160 by wire in FIG. 1, it may be connected to the control unit 160 by wireless communication such as Wi-Fi (registered trademark) and Bluetooth.

The elevating unit 130 includes a stage 120 on which a metal-air battery is placed, and the stage 120 is at a measurement position of the weight measuring unit 110 (left figure in FIG. 1) and a position where the stage 120 is separated from the weight measuring unit 110 (FIG. 1). It is equipped with a drive mechanism such as a motor that repeatedly raises and lowers (the figure on the right). In this way, the weight of the metal-air battery is measured by the elevating unit 130 at intervals set by the user. As a result, the weight measurement of the metal-air battery is zero-point corrected for each measurement, and the weight of the metal-air battery is accurately measured. Although the elevating unit 130 is connected to the control unit 160 by wire in FIG. 1, it may be connected to the control unit 160 by wireless communication such as Wi-Fi (registered trademark) and Bluetooth.

The housing 140 accommodates at least the weighing pan of the weight measuring unit 110 and the metal-air battery, and functions to control the environment such as temperature and atmosphere at the time of measurement. The housing 140 may preferably include a gas air supply port 170 and a gas exhaust port 180, and the gas air supply port 170 may be connected to an atmosphere control gas so that the atmosphere inside the housing 140 can be controlled. As such an atmosphere control gas, oxygen gas, carbon dioxide gas, and noble gases such as nitrogen, argon, helium, and xenon can be adopted. In FIG. 1, the housing 140 is shown to include the elevating unit 130 in addition to the weight measuring unit 110 and the metal-air battery, but it is not essential that the housing 140 includes the elevating unit 130.

The charge / discharge characteristic measuring unit 150 may be a charge / discharge tester that measures the discharge charge / discharge characteristics at the time of rest (pause or no current) of the metal-air battery, charging and discharging. The charge / discharge characteristic measuring unit 150 is connected to the metal-air battery via a conducting wire. Such a conducting wire is not particularly limited, but a copper wire, a carbon nanotube wire, a gold wire or the like having a diameter of 10 μm or more and 250 μm or less can be used in consideration of the influence on the weight change amount of the weight measuring unit 110. Among them, a gold wire having a diameter of 10 μm or more and 50 μm or less is preferable because it has a small influence on the amount of weight change.

Although the charge / discharge characteristic measuring unit 150 is connected to the control unit 160 by wire in FIG. 1, it may be connected to the control unit 160 by wireless communication such as Wi-Fi (registered trademark) and Bluetooth. .. Further, the charge / discharge characteristic measuring unit 150 does not need to be housed in the housing 140, but may be housed depending on the capacity of the housing 140.

The evaluation device 100 of the present invention may further include a temperature detection unit 190 in the housing 140. Thereby, the temperature inside the housing 140 can be measured. Such a temperature detection unit 190 may be a thermocouple as an example. Although the temperature detection unit 190 is connected to the control unit 160 by wire in FIG. 1, it may be connected to the control unit 160 by wireless communication such as Wi-Fi (registered trademark) and Bluetooth.

The evaluation device 100 of the present invention may further include an atmospheric pressure detection unit (not shown) in the housing 140. As a result, the atmospheric pressure inside the housing 140 can be measured. Such a barometric pressure detector may be, for example, a barometer. Like the temperature detection unit 190, the barometric pressure detection unit may be connected to the control unit 160 by wire or wirelessly. The evaluation device 100 may include both the temperature detection unit 190 and the atmospheric pressure detection unit, or either one, but by providing both, the influence of the temperature and the atmospheric pressure on the weight change amount of the metal-air battery is affected. Since the measurement can be performed in consideration, highly accurate evaluation is possible.

The evaluation device 100 of the present invention may further include a temperature control device (not shown) for holding the temperature inside the housing 140. As a result, the temperature inside the housing 140 can be kept constant. Such a temperature control device can be heated and / or cooled, and a constant temperature tester, a constant temperature bath, or the like can be adopted. The temperature control device may also be connected to the control unit 160 by wire or wirelessly.

The control unit 160 controls the operation of the elevating unit 130, the weight measurement unit 110, and the charge / discharge characteristic measurement unit 150, and based on the information acquired by the weight measurement unit 110 and the charge / discharge characteristic measurement unit 150, the metal-air battery Evaluate battery characteristics. Such a control unit 160 may be a general-purpose personal computer or a dedicated terminal device. FIG. 1 shows, as an example, a personal computer provided with an input device such as a keyboard and a mouse and a display device such as a display as the control unit 160.

FIG. 2 is a block diagram showing a configuration of a control unit of the evaluation device of the present invention.

The control unit 160 raises and lowers the stage 120 of the elevating unit 130 as a functional block, executes measurement by the weight measuring unit 110 and the charging / discharging characteristic measuring unit 150, and acquires the weight change amount and the charging / discharging characteristic of the metal air battery. It includes a measurement control unit 210 and a calculation / evaluation unit 220 that calculates / evaluates the battery characteristics of a metal air battery based on the weight change amount and charge / discharge characteristics acquired by the measurement control unit 210.

In the evaluation device 100 of the present invention, the elevating unit 130 measures the amount of change in the weight of the metal-air battery while repeating the measurement position and the distance from the stage 120, so that the zero point correction of the weight measuring unit is measured every time. Can be done. As a result, the amount of change in weight of the metal-air battery can be accurately measured over a long period of time. Furthermore, since the charge / discharge characteristics are measured at the same time as the amount of weight change, the charge / discharge reaction efficiency of the metal-air battery can be calculated and evaluated with high accuracy. From this point of view, in the present specification, the evaluation of the battery characteristics is intended to evaluate the metal-air battery by the charge / discharge characteristics.

The control unit 160 may include a display unit 230 that displays the result of the calculation / evaluation unit 220. The display unit 230 is, for example, a liquid crystal display. In addition to the result, the display unit 230 may display a screen for setting measurement conditions of the weight measuring unit 110 and the charge / discharge characteristic measuring unit 150 performed by the measurement control unit 210.

The control unit 160 may include an input unit 240 that receives an input operation from the user. The input unit 240 is, for example, a keyboard, a mouse, a button, a touch panel, a touch sensor, a touch pen, a voice input, or the like.

The control unit 160 includes a measurement control unit 210, various programs (evaluation programs) executed by the calculation / evaluation unit 220, etc., an OS program, an application program, and a storage unit 250 that records various data to be read when these are executed. You may be. The storage unit 250 stores the amount of change in weight measured by the weight measuring unit 110 and the charging / discharging characteristic measured by the charging / discharging characteristic measuring unit 150 in association with each other. Such a storage unit 250 is a non-volatile storage device such as a hard disk or a flash memory.

The control unit 160 may include a weighing value correction unit 260 that corrects the amount of change in weight by the weight measurement unit 110. The weighing value correction unit 260 is a weight measuring unit 110 when a fluctuation of the weighing value occurs due to the temperature fluctuation and / or the atmospheric pressure fluctuation measured by the temperature detecting unit 190 and / or the atmospheric pressure detecting unit (not shown). Correct the weighing value with the sensitivity drift value. The sensitivity drift value may be provided in advance by the weight measuring unit 110, or immediately before the measurement, it is investigated whether or not there is a temperature fluctuation / atmospheric pressure fluctuation dependence of the change in the weighing value of an immutable heavy product such as a weight or a cell holder, and the change amount is determined. It may be set accordingly. From such a viewpoint, the measurement control unit 210 may acquire the weight change amount (weighing value) of the immutable weight product in addition to the metal-air battery.

The calculation / evaluation unit 220 will be described in more detail with reference to FIG.
The control unit 160 further includes an electrolytic solution volatilization rate calculation unit 221, a discharge weight change amount calculation unit 222, a reaction electron number calculation unit 223, a charge weight change amount calculation unit 224, and a capacitance calculation unit 225 as functional blocks. You may be prepared.

The calculation / evaluation unit 220 preferably includes an electrolytic solution volatilization rate calculation unit 221 that calculates the rate at which the electrolytic solution in the metal-air battery spontaneously volatilizes with the elapsed time. Electrolyte volatilization rate calculation unit 221, a weight change amount _{W tr} time _{t r} during rest of the charge and discharge characteristics due to charge-discharge characteristic measurement unit 150, the time _{t r0 (However, t r>} t _r0) the change in weight of dividing the change in weight difference _wt r _{-wt r0} and wt _r0 time difference _t r _{-t r0,} calculates the electrolyte volatilization rate _{((wt r -Wt r0) /} (t r -t r0)). An exemplary time difference is a time difference of 30 minutes or more and 50 hours or less. By using this time difference, the electrolytic solution volatilization rate can be calculated. Here, electrolyte evaporation rate calculation unit 221 reads the change in weight between the time _{t r} and _{t r0} from the storage unit 250. Hereinafter, the electrolytic solution volatilization rate is referred _{to as r vol.}

The calculation / evaluation unit 220 preferably includes a discharge weight change amount calculation unit 222 that calculates the weight change amount of the metal-air battery caused only by the discharge reaction. Discharge weight change calculator 222, from the change in weight at time t _d during the discharge of the charge-discharge characteristics due to charging and discharging characteristic measuring section 150 subtracts the electrolyte volatilization amount naturally volatilized until the time t _d, which Is the amount of change in discharge weight.

In particular, the discharge weight change calculator 222, and the change in weight Wt _d of time _{t d} during the discharge of the charge-discharge characteristics, time _{t d0 (However, t d>} t _d0) and the change in weight _{Wt d0} of from weight change amount difference _(wt d _{-Wt d0),} it calculates the time amount of electrolyte solution spontaneously volatilize during _{(t d -t d0) (r} vol x (t d -t d0)) The amount of change in discharge weight is reduced to ((Wt _{d − Wt d0} ) − (r _vol x (t _d −t _d0 ))). Here, r _vol is the electrolytic solution volatilization rate obtained earlier.

Thus, discharge weight change amount calculation unit 222 reads the change in weight Wt _d of time t _d from the storage unit 250, the time t _d calculated using the electrolyte volatilization rate during rest just before discharge from the value Reduces the amount of electrolyte volatilized in. The electrolytic solution volatilization rate is a value calculated by the electrolytic solution volatilization rate calculation unit 221. Further, "rest immediately before discharge" means a rest before discharge in the case of charge / discharge characteristics in the order of rest, discharge, rest, and charge, and in the case of charge / discharge characteristics in the order of rest, discharge, and charge. Is intended to be a rest before discharge.

The discharge weight change amount calculation unit 222 may be calculated at predetermined time intervals according to the user's setting, or may be calculated every time the weight change amount of the metal-air battery is measured.

The calculation / evaluation unit 220 preferably includes a reaction electron number calculation unit 223 that calculates the number of electrons reacting with oxygen in the metal-air battery during the discharge reaction. The reaction electron number calculation unit 223 divides the weight change amount caused only by the discharge reaction _{of the time interval Δt d} during discharge of the charge / discharge characteristics calculated by the discharge weight change amount calculation unit 222 _{by the time interval Δt d} . The weight change rate is calculated, and the current value used for measuring the charge / discharge characteristics is divided by this weight change rate, and this is taken as the number of reaction electrons. The exemplary time interval Δt _d is in the range of 1 second or more and 60 seconds or less.

For example, when the metal-air battery is a lithium-air battery, an electrochemical reaction represented by the following equation occurs during discharge.
_{^{2Li + + 2e - + O 2}} → Li 2 O 2
Therefore, the closer the number of reaction electrons is to +2, the more it can be evaluated that the lithium-air battery has excellent discharge efficiency.

The calculation / evaluation unit 220 preferably includes a charge weight change amount calculation unit 224 that calculates the weight change amount of the electrolytic solution in the metal-air battery due only to the charge reaction. The charge weight change amount calculation unit 224 reduces the amount of electrolyte volatilized naturally volatilized by _{that time t c} from the amount of weight change at _{time t c} during charging of the charge / discharge characteristics by the charge / discharge characteristic measurement unit 150. Is the charge weight conversion amount.

In particular, the charge weight change amount calculating unit 224, and the change in weight Wt _c at time _{t c} in the charge of the charge-discharge characteristics, the time _{t c0 (However, t c>} t _c0) and the change in weight _{Wt c0} of from weight change amount difference _(wt c _{-Wt c0),} this by calculating the time amount of electrolyte solution spontaneously volatilize during _{(t c -t c0) (r} vol x (t c -t c0)) The amount of change in charge weight is reduced to ((Wt _{c − Wt c0} ) − (r _vol x (t _c −t _c0 ))). Here, too, r _vol is the electrolytic solution volatilization rate obtained earlier.

In this way, the charge weight change amount calculation unit 224 _{reads the weight change amount at time t c from the storage unit 250, and electrolyzes at time t c} calculated from this value using the electrolytic solution volatilization rate at the time of rest immediately before charging. Reduce the amount of liquid volatilization. The electrolytic solution volatilization rate is a value calculated by the electrolytic solution volatilization rate calculation unit 221.

The charge weight change amount calculation unit 224 may be calculated at predetermined time intervals according to the user's setting, or may be calculated every time the weight change amount of the metal-air battery is measured.

The reaction electron number calculation unit 223 may calculate the number of electrons required for discharging oxygen from the metal-air battery during the charging reaction. In this case, the reaction electron number calculation unit 223 determines the amount of weight change due only to the charging reaction _{at the time interval Δt c} during charging of the charge / discharge characteristics calculated by the charge weight change amount calculation unit 224 at _{the time interval Δt c} . Divide to calculate the weight change rate, divide the current value used for measuring the charge / discharge characteristics by this weight change rate, and use this as the number of reaction electrons. The exemplary time interval Δt _c is in the range of 1 second or more and 60 seconds or less.

For example, when the metal-air battery is a lithium-air battery, an electrochemical reaction represented by the following formula occurs during charging.
_{^{2Li + + 2e - + O 2}} ← Li 2 O 2
Therefore, the closer the number of reaction electrons is to -2, the more it can be evaluated that the lithium-air battery has excellent charging efficiency.

As described above, the reaction electron number calculation unit 223 may calculate the number of electrons required for oxygen absorption / discharge only during discharging, charging, or both discharging and charging.

The calculation / evaluation unit 220 preferably includes a capacitance calculation unit 225 for calculating the capacitance. The capacitance calculation unit 225 calculates from the time ΔT required after the start of discharge of the charge / discharge characteristics and until the weight change occurs, and the current value (mA) passed during the time ΔT. Specifically, the capacitance (mAh) is based on the following equation. It can be seen that the discharge of only the calculated capacitance is in progress.
Capacitance (mAh) = current (mA) x time ΔT

Next, the operation of the evaluation device 100 of the present invention will be described.
When the metal air battery to be evaluated is placed on the stage 120 of the elevating unit 130 and the atmospheric gas and temperature in the housing 140 are controlled as needed, the measurement control unit 210 of the control unit 160 uses the user. Receives the measurement conditions of the weight measurement unit 110 and the charge / discharge characteristic measurement unit 150 from the above, raises and lowers the stage 120 of the elevating unit 130, and simultaneously executes the measurements of the weight measurement unit 110 and the charge / discharge characteristic measurement unit 150, and the amount of weight change. And the charge / discharge characteristics are continuously acquired. The acquired data related to the amount of weight change and the charge / discharge characteristics may be temporarily stored in the measurement control unit 210 or stored in the storage unit 250 in association with each other according to the elapsed time, for example. Here, it is assumed that the data is acquired and stored in the storage unit 250.

Next, the calculation / evaluation unit 220 of the control unit 160 reads the acquired weight change amount and charge / discharge characteristic data from the storage unit 250, and calculates and evaluates the battery characteristics of the metal-air battery. Specifically, the calculation / evaluation unit 220 receives the evaluation conditions from the user, the electrolytic solution volatilization rate calculation unit 221 calculates the electrolytic solution volatilization rate, and the discharge weight change amount calculation unit 222 changes the weight during the discharge reaction. The amount is calculated, the charge weight change amount calculation unit 224 calculates the weight change amount during the charge reaction, and the reaction electron number calculation unit 223 is used for absorbing and discharging air during the discharge reaction and / or the charge reaction. The required number of electrons is calculated, and the capacitance calculation unit 225 calculates the capacitance. These evaluations may be performed at the same time, or one of them may be selected. The control unit 160 may display these results on the display unit 230.

The calculation / evaluation unit 220 can evaluate the performance of the metal-air battery for a long period of time by using the data of the weight change amount and the charge / discharge characteristics associated with each other. Further, since the weight change amount of the metal-air battery is zero-point corrected for each measurement, the obtained performance evaluation is highly accurate and highly reliable.

FIG. 3 is a diagram showing an exemplary graphical user interface (GUI) screen.

FIG. 3 shows an exemplary GUI screen as an operation screen for the user to operate the evaluation device 100. The operation screen may be displayed on the display unit 230 of the control unit 160. Such screen operations are performed by the above-mentioned input unit 240.

The top page 300 includes a weight measurement condition setting button 310, a charge / discharge characteristic measurement condition setting button 320, an evaluation item setting button 330, a measurement execution button 340, a result button 350, and an end button 360.

FIG. 4 is a diagram showing an exemplary weight measurement condition setting screen.

When the user selects the weight measurement condition setting button 310, the screen moves to the weight measurement condition setting screen 400. The user appropriately sets the conditions for measuring the weight of the metal-air battery and the immutable weight product. For example, in FIG. 4, it is possible to set the ascending / descending speed of the stage 120 included in the elevating unit 130, the measurement cycle, the number of measurements, the waiting time until weight measurement, and the waiting time until Tare. In FIG. 4, the weighing value correction is turned off. Further, the weight measurement condition setting screen 400 may display the weight at the time of measurement, the current number of measurements, the elapsed time, and the like in real time.

Enter the weight measurement condition settings, select the setting button, confirm the measurement conditions, and then return to the top page 300. When the measurement execution button 340 is selected, the measurement control unit 210 sends the measurement conditions set in the weight measurement conditions to the elevating unit 130 and the weight measuring unit 110, and the elevating unit 130 moves the stage 120 up and down while moving the metal-air battery. Carry out a weight measurement. Here, since the charge / discharge characteristic measurement conditions are not input, only the weight measurement of the metal-air battery is performed. When the measurement is completed and the result button 350 is selected, the result is displayed.

FIG. 5 is a diagram showing an exemplary weight measurement result.

When the evaluation device 100 includes the temperature detection unit 190, the measurement result 500 shows the time change of the temperature inside the housing 140 and the time change of the weight change amount of the metal-air battery. FIG. 5 shows how the weighed value of the load, which is an immutable heavy product, changes (drifts) as the temperature increases or decreases.

FIG. 6 is a diagram showing another exemplary weight measurement condition setting screen.

FIG. 6 shows the weight measurement condition setting screen 600, which is different from FIG. 4 in that the weighing value correction is turned on. The weighing value correction unit 260 of the control unit 160 corrects the weighing value based on the sensitivity drift value. The result of measurement execution after setting is shown in FIG.

FIG. 7 is a diagram showing another exemplary weight measurement result.

When the weighing value correction is turned on, the measurement result 700 shows that the weighing value of the load becomes constant regardless of the increase or decrease in temperature. In this way, by turning on the weighing value correction, the weighing value correction unit 260 automatically corrects the weighing value using the sensitivity drift value. Such a corrected amount of weight change is constant regardless of fluctuations in temperature and atmospheric pressure. The sensitivity drift value may be a sensitivity drift value previously possessed by the weight measuring unit 110, or may be set using the drift value shown in FIG.

FIG. 8 is a diagram showing an exemplary charge / discharge characteristic measurement condition setting screen.

Returning to FIG. 3 again, when the user selects the charge / discharge characteristic measurement condition setting button 320, the screen moves to the charge / discharge characteristic measurement condition setting screen 800. Here, the user selects a sequence related to the number of repeated measurements of charging / discharging (number of cycles), and selects a pattern for setting the charging electricity amount at the time of charging, the rest, and the discharging capacity at the time of discharging.

In FIG. 8, the user can see the sequence No. on the sequence tab. 1 is selected, and the sequence No. 1 is the pattern No. Using 2, it can be seen that the number of cycles consists of a sequence of 20 times. Further, the user can display the sequence No. on the sequence tab. Pattern No. 1 cited in 1. Set the details of 2 (mode, control time, recording time interval, cutoff (target) voltage, current). It can be seen that the target voltage is 2V to 4.5V.

If various sequences and various patterns are stored in the storage unit 250 in advance, it is only necessary to read them out.

FIG. 9 is a diagram showing an exemplary evaluation item setting screen.

Enter the weight measurement condition settings and charge / discharge characteristics measurement condition settings, select the setting button, confirm the measurement conditions, and then return to the top page 300. When the evaluation item setting button 330 is selected, the evaluation item setting screen 900 for setting various evaluations of the metal-air battery shown in FIG. 9 is displayed. Here, various evaluation items such as electrolytic solution volatilization rate, weight change amount due to discharge reaction, electron number calculation due to discharge reaction, weight change amount due to charge reaction, electron number calculation due to charge reaction, capacitance calculation, etc. are performed. You can choose. The user can select a desired evaluation item and input a calculation interval and the like.

In this way, when the weight measurement condition setting, the charge / discharge characteristic measurement condition setting, and the evaluation item setting are input, the top page 300 is returned, and the measurement execution button 340 is selected, the measurement control unit 210 measures the weight. The measurement conditions set in the conditions and charge / discharge characteristic measurement conditions are sent to the elevating unit 130, the weight measuring unit 110, and the charge / discharge characteristic measuring unit 150, and the elevating unit 130 raises and lowers the stage 120 to measure the weight of the metal air battery. And the charge / discharge characteristics are measured.

FIG. 10 is a diagram showing exemplary results.
FIG. 11 is a diagram showing another exemplary result.

When the measurement is completed and the result button 350 on the top page 300 is selected, the result screens 1000 and 1100 shown in FIGS. 10 and 11 are displayed. The result screen 1000 shows the change in the amount of electrolyte volatilization based on the electrolyte volatilization rate selected on the evaluation item setting screen 900, in addition to the net weight change amount and charge / discharge characteristics of the metal-air battery.

When the next page is selected on the result screen 1000, the result screen 1100 is displayed. The result screen 1100 shows the amount of change in weight due to the charge / discharge reaction selected on the evaluation item setting screen 900, the rate of change in weight due to the charge / discharge reaction, and the change in the number of reaction electrons in the charge / discharge reaction. Here, in order to show the case of a lithium-air battery as the metal-air battery, since air to be exchanged with the outside is oxygen, the number of electrons is ^- labeled "e / O _2". Focusing on the number of reaction electrons during the charging reaction of the result screen 1100, it shows a tendency to deviate from -2 with the elapsed time, suggesting that the normal charging reaction does not proceed.

Return to the top page 300 from the result screens 1000 and 1100 and select the end button 360 to end the application. In this way, the evaluation device 100 of the present invention can carry out the battery evaluation of the metal-air battery over time based on the accurate weight change.

In addition to the result screens shown in FIGS. 10 and 11, the measurement results before the characteristic evaluation of the weight change amount and the charge / discharge characteristics of the metal-air battery may be displayed.

Next, the evaluation method of the metal-air battery of the present invention will be described. The evaluation method of the present invention will be described as being carried out using the evaluation device shown in FIG. 1, but is not limited to the evaluation device of the present invention. The evaluation method of the present invention may be carried out by adopting any device capable of carrying out each step.
FIG. 12 is a flowchart showing a method for evaluating the battery characteristics of the metal-air battery of the present invention.

Step S1210: Atmosphere control gas is flowed into the measurement environment such as the housing 140. As a result, the atmosphere of the measurement environment of the metal-air battery is controlled. The atmosphere control gas may be an oxygen gas, a carbon dioxide gas, and a rare gas such as nitrogen, argon, helium, or xenon. Although step S1210 is not essential, more accurate battery evaluation can be performed by controlling the measurement environment.

Step S1220: The arrangement of the metal-air battery at the measurement position of the weight measuring unit 110 (left figure in FIG. 1) and the separation of the metal-air battery from the measurement position (right figure in FIG. 1) are repeated to obtain the metal-air battery. Weigh repeatedly. As a result, the zero point is corrected every time the weight of the metal-air battery is measured, and an accurate weight change amount can be obtained.

Such repeated measurement of the weight of the metal-air battery is performed by the elevating unit 130 raising and lowering the stage 120 on which the metal-air battery is placed at regular intervals. When the metal-air battery is separated from the measurement position, the zero point correction of the weight measuring unit 110 is performed, and when the metal-air battery reaches the measurement position, the weight measuring unit 110 measures the weight of the metal-air battery. The measured weight change amount is stored in, for example, the storage unit 250 of the control unit 160 of the evaluation device 100.

Step S1230: At the same time as step S1220, the charge / discharge characteristics of the metal-air battery are measured. Since the measurements are taken at the same time, the charge / discharge characteristics can be associated with the amount of change in weight over time, which is zero-point corrected for each weight measurement. The charge / discharge characteristics are performed by a charge / discharge tester or the like. The measured charge / discharge characteristics are stored in a storage unit 250 or the like of the control unit 160 of the evaluation device 100, and are stored in association with the value of the weight change amount, for example, by time.

Step S1240: The metal-air battery is calculated and evaluated based on the weight change amount obtained in step S1220 and the charge / discharge characteristic data obtained in step S1230. In this way, the electrolyte volatilization rate associated with the charge / discharge reaction of the metal-air battery, the amount of weight change associated with the charge / discharge, and the number of reaction electrons associated with the charge / discharge are based on the accurate weight change amount and charge / discharge characteristics associated with each other. , Since the battery characteristics such as capacitance are calculated and evaluated, the performance evaluation of the metal-air battery can be continuously performed with high accuracy for a long period of time. The calculation / evaluation is performed by the control unit 160 of the evaluation device 100.

The calculation / evaluation of step S1240 will be described in more detail.
The calculation / evaluation preferably calculates the rate at which the electrolytic solution in the metal-air battery spontaneously volatilizes with the elapsed time. And the change in weight _{W tr} time _{t r} during rest of the charge-discharge characteristics, time _{t r0 (However,} t _{r> t r0)} the change in weight difference between the change in weight _{Wt r0} of _Wt r _{-wt r0} the time difference t divided by the _r -t _r0, to calculate the electrolyte evaporation rate _{((Wt r -Wt r0) /} (t r -t r0)). An exemplary time difference is a time difference of 30 minutes or more and 50 hours or less. By using this time difference, the electrolytic solution volatilization rate can be calculated accurately. Here, reading out the change in weight between the time _{t r} and _{t r0} from the storage unit 250, to be used in the calculation. The electrolytic solution volatilization rate is called _{r vol.}

The calculation / evaluation preferably calculates the amount of change in the weight of the metallic air due only to the discharge reaction. The amount of change in discharge weight is calculated by subtracting the amount of volatilization of the electrolytic solution that naturally volatilized by _{that time t d} from the amount of change in weight at _{time t d} during discharge of the charge / discharge characteristics.

In particular, the change in weight Wt _d of time _{t d} during the discharge of the charge-discharge characteristics, time _{t d0 (However, t d>} t _d0) the change in weight difference between the change in weight _{Wt d0} of (Wt _d - From Wt _d0 ), calculate the amount of electrolyte (r _vol x (t _d- t _d0 )) that naturally volatilized during the time (t _d- t _d0 ), subtract this, and subtract the amount of change in discharge weight ((Wt-t d0)). _d −Wt _d0 ) − (r _vol x (t _d −t _d0 ))). r _vol is the electrolytic solution volatilization rate obtained earlier.

Specifically, the weight change amount Wt _{d at time t d} is read from the storage unit 250, and the electrolyte volatilization amount at _{time t d} calculated by using the electrolyte volatilization rate at the rest immediately before discharge is subtracted from this value. The "rest immediately before discharge" is intended to be a rest before discharge in the case of charge / discharge characteristics in the order of rest, discharge, rest, and charge, and in the case of charge / discharge characteristics in the order of rest, discharge, and charge. , Intended to rest before discharge.

The amount of change in discharge weight may be calculated at predetermined time intervals according to the user's settings, or may be calculated each time the amount of change in weight of the metal-air battery is measured.

The calculation / evaluation preferably calculates the number of electrons reacting with the air of the metal-air battery during the discharge reaction. The amount of weight change caused only by the discharge reaction _{at the time interval Δt d} during discharge of the charge / discharge characteristics _{is divided by the time interval Δt d} to calculate the weight change rate, and the current value used for measuring the charge / discharge characteristics is this. Divide by the rate of weight change to calculate the number of air reaction electrons. The exemplary time interval Δt _d is in the range of 1 second or more and 60 seconds or less.

The calculation / evaluation preferably calculates the amount of change in the weight of the electrolytic solution in the metal-air battery due only to the charging reaction. The charge weight conversion amount is calculated by subtracting the volatilization amount of the electrolytic solution naturally volatilized by _{that time t c} from the weight change amount at _{time t c} during charging of the charge / discharge characteristics.

In particular, the change in weight Wt _c at time _{t c} in the charge of the charge-discharge characteristics, the time _{t c0 (However, t c>} t _c0) the change in weight difference between the change in weight _{Wt c0} of (Wt _c - From Wt _c0 ), calculate the amount of electrolyte (r _vol x (t _c- t _c0 )) that naturally volatilized during the time (t _c- t _c0 ), subtract this, and subtract the amount of change in charge weight ((Wt c0)). _c- Wt _c0 )-(r _vol x (t _c- t _c0 ))). r _vol is the electrolytic solution volatilization rate obtained earlier.

_{In this way, the amount of change in weight at time t c} is read from the storage unit 250, and the _{amount of electrolyte volatilization at time t c} calculated using the electrolyte volatilization rate at the time of rest immediately before charging is subtracted from this value. For the electrolytic solution volatilization rate, the value calculated above is used.

The charge weight change amount may be calculated at predetermined time intervals according to the user's setting, or may be calculated each time the weight change amount of the metal-air battery is measured.

The calculation / evaluation preferably calculates the number of electrons required to discharge oxygen from the metal-air battery during the charging reaction. The amount of weight change caused only by the charging reaction _{of the time interval Δt c} during charging of the charge / discharge characteristics _{is divided by the time interval Δt c} to calculate the weight change rate, and the current value used for measuring the charge / discharge characteristics is this. Divide by the rate of weight change to calculate the number of reaction electrons. The exemplary time interval Δt _c is in the range of 1 second or more and 60 seconds or less.

The calculation / evaluation preferably calculates the capacitance. The capacitance is calculated from the time ΔT required after the start of discharge of the charge / discharge characteristics and until the weight change occurs, and the current value (mA) flowing during the time ΔT. Specifically, the capacitance (mAh) is based on the following equation.
Capacitance (mAh) = current (mA) x time ΔT

FIG. 13 is a flowchart showing a method for evaluating the battery characteristics of another metal-air battery of the present invention.

Step S1310: Prior to step S1210 in FIG. 12, the arrangement of the immutable heavy goods such as the weight and the cell holder at the measurement position of the weight measuring unit 110 (left figure in FIG. 1) and the separation of the immutable heavy goods from the measurement position (the left figure of FIG. 1). The weight of the immutable weight product is repeatedly measured by repeating (the right figure of FIG. 1). Since this step is the same as step S1220, the description thereof will be omitted.

Step S1320: At the same time as step S1310, the temperature change in the measurement environment inside the housing 140 and / or the atmospheric pressure change inside the housing 140 are measured. Since it is measured at the same time, temperature change and / or barometric pressure change can be associated with the amount of weight change. The measured temperature change and / or barometric pressure change data is stored, for example, in the storage unit 250 of the control unit 160 of the evaluation device 100 in association with the value of the weight change amount in time.

Step S1330: Determine whether the weighed value of the immutable weight product fluctuates due to temperature change and / or atmospheric pressure change. Normally, it is known that a temperature change of about ± 1 ° C. and a pressure change of about ± 20 Pa occur even in a limited space such as a housing 140, and with such a slight change, it is known. When the amount of change in weight increases or decreases within the range of ± 5 ppm (± 0.0005%), it is determined that the weighed value has changed. If the range of increase / decrease in the amount of weight change is within the above range, the effect on the battery evaluation is small and can be ignored. Such a determination may be made by the control unit 160 by comparing the values of the weight change amount, the temperature change, and the atmospheric pressure change.

If it is determined that the weighed value of the immutable heavy product fluctuates due to temperature change and / or atmospheric pressure change, the process proceeds to step S1330. If it is not determined that the weighed value of the immutable weight product is fluctuating due to temperature change and / or atmospheric pressure change (that is, it is determined that the weighed value is not fluctuating), the weighing value is not corrected, and step S1210 is performed. Proceed to evaluate the metal-air battery.

Step S1340: In step S1330, when it is determined that the weighed value of the immutable weight product fluctuates due to temperature change and / or atmospheric pressure change, the weighed value is corrected by the sensitivity drift value of the weight measuring unit 110. .. The sensitivity drift value may be a value provided in the weight measuring unit 110 in advance, or may be set according to the amount of change obtained in step S1320. As a result, the effects of temperature and atmospheric pressure on the amount of weight change of the metal-air battery can be taken into consideration, which enables highly accurate evaluation. Next, the process proceeds to step S1210 to evaluate the metal-air battery. The following procedure has been described with reference to FIG. 12, and will be omitted.

Each functional block in the control unit 160 of the evaluation device 100 of the present invention described with reference to FIG. 2 may be configured by hardware logic, or may be realized by software using a CPU (Central Processing Unit). good.

The evaluation device 100 of the present invention includes a CPU (not shown) that executes instructions of a program that realizes each function, a ROM (Read Only Memory, not shown) that stores the program, and a RAM (Randam Access) that expands the program. A recording medium such as a memory (not shown), a memory for storing a program and various data may be provided. A computer or a CPU may read and execute the program code recorded on the recording medium on a recording medium in which the program code of a program that is software that realizes the above-mentioned functions is readablely recorded by a computer. In this way, a method of evaluating the battery characteristics of the metal-air battery by the evaluation device 100 can be realized.

Such recording media include, for example, disks such as CD-ROMs, cards such as IC cards, and semiconductor memories such as flash ROMs.

The evaluation device 100 of the present invention may be connected to a communication network, and the program code may be supplied via the communication network. Such a communication network is not particularly limited, and may be, for example, the Internet, an intranet, a LAN, an ISDN, a CATV communication network, a telephone line network, a satellite communication network, or the like. The program code may be in the form of a computer data signal embodied in electronic transmission and embedded in a carrier wave.

Next, the present invention will be described in detail with reference to specific examples, but it should be noted that the present invention is not limited to these examples.

[Example 1]
In Example 1, the evaluation device of FIG. 1 was constructed and the battery characteristics of the lithium ion battery were evaluated. Since the lithium ion battery is weight-invariant, it was used as an invariant weight product.

The weight measuring unit 110 in FIG. 1 is an electronic balance (A & D Co., Ltd., AD-4212B-23), and the charge / discharge characteristic measuring unit 150 is a charge / discharge tester (ECAD-1000, manufactured by EC Frontier Co., Ltd.). A thermocouple was used as the temperature detection unit 190, and a personal computer was used as the control unit 160. The lithium ion battery was a CR-2032 coin cell battery in which a Li metal foil / LFP (LiFePO ₄ : lithium iron phosphate) positive electrode (φ16 mm) was opposed to each other.

A lithium-ion battery was placed on the stage 120, which is a battery holder. The battery holder could be raised and lowered by the raising and lowering unit 130. The weight measuring unit 150 and the elevating unit 130 were housed in a housing 140 (internal volume 5L) having a gas supply port and a gas exhaust port. The lithium ion battery was electrically contacted with the charge / discharge tester by a gold wire having a diameter of 30 μm. The cables and conductors required to control the electronic balance, elevating part, and charge / discharge tester were wired through the gas exhaust port and connected to a personal computer or the like.

FIG. 14 is a diagram showing a charge / discharge characteristic measurement condition setting screen of Example 1.

The battery characteristics of the lithium ion battery were evaluated under the same weight measurement conditions as in FIG. 4 and the charge / discharge characteristic measurement conditions shown in FIG. The results are shown in FIG.

FIG. 15 is a diagram showing the weight change amount and charge / discharge characteristics of the lithium ion battery of Example 1.

According to FIG. 15, it was found that the weight of the lithium ion battery hardly changed for 7 days (168 hours), and the lithium ion battery could be normally charged and discharged.

[Example 2]
In Example 2, the battery characteristics of the lithium-ion battery were evaluated in the same manner as in Example 1 under the same weight measurement conditions as in FIG. 4 (that is, the same weight measurement conditions as in FIG. 6) except that the weighing value correction was turned on. The results are shown in FIGS. 16 and 17. The sensitivity drift value of the electronic balance was 2.8 ppm / ° C.

FIG. 16 is a diagram showing a weight change amount and a temperature change of the lithium ion battery of Example 1.
FIG. 17 is a diagram showing a weight change amount and a temperature change of the lithium ion battery of Example 2.

Note that the temperature changes in FIGS. 16 and 17 are temperature changes inside the housing. FIG. 16 is a diagram showing an enlarged amount of weight change in FIG. 15 in Example 1 together with a temperature change. According to FIG. 16, it was found that the temperature fluctuates at ± 1 ° C. even inside the housing, and the weighed value of the lithium ion battery also fluctuates at ± 40 μg following this temperature fluctuation.

On the other hand, according to FIG. 17, the weighing value of the lithium ion battery of Example 2 was constant without following the temperature change, and was continuously weighed with a standard deviation of 8 μg. The standard deviation of this weighed value was also valid from the accuracy specifications of the electronic balance. From this, it was shown that the weight correction based on the sensitivity drift value of the weight measuring unit is effective. In all subsequent examples, measurements were taken with weighing value correction turned on.

[Example 3]
In Example 3, the evaluation device constructed in Example 1 was used to evaluate the battery characteristics (1 cycle of rest, discharge, and charge) of the lithium-air battery cell while flowing pure oxygen into the housing (flow velocity 150 mL / min). The lithium-air battery cell is a CR-2032 coin cell in which a Li metal foil / CNT carbon nanotube air electrode (φ16 mm) is opposed to each other, and a large number of air holes (φ0.7 mm) for absorbing and discharging oxygen are provided on the air electrode side. Had.

FIG. 18 is a diagram showing a charge / discharge characteristic measurement condition setting screen of Example 3.

The battery characteristics of the lithium-air battery were evaluated under the weight measurement conditions shown in FIG. 6 and the charge / discharge characteristic measurement conditions shown in FIG. As the evaluation items of the battery characteristics, the calculation of the electrolytic solution volatilization rate shown in FIG. 9, the calculation of the weight change amount associated with the charge reaction / discharge reaction, and the calculation of the number of electrons associated with the charge reaction / discharge reaction were selected. The time interval of the electrolyte volatilization rate is 50 hours, the amount of weight change due to the charge reaction / discharge reaction is performed every time the weight is measured, and the time interval for calculating the number of electrons associated with the charge reaction / discharge reaction is every 30 seconds. rice field. The results are shown in FIGS. 19 and 20.

FIG. 19 is a diagram showing the results of the battery characteristics of the lithium-air battery of Example 3.
FIG. 20 is a diagram showing another result of the battery characteristics of the lithium-air battery of Example 3.

According to FIG. 19, it was found that the electrolytic solution volatilization rate at the time of rest was −5.63 (± 0.06) μg / h, and the electrolytic solution contained in the lithium-air battery volatilized naturally. Do you get it.

The upper part of FIG. 20 shows the amount of weight change due to the charge reaction / discharge reaction calculated from the electrolyte volatilization rate of FIG. In the middle of FIG. 20, the weight change rate is shown in the charge reaction / discharge reaction calculated from the amount of weight change accompanying the charge reaction / discharge reaction. The lower part of FIG. 20 shows the air reaction / number of discharged electrons calculated from the weight change rate and the current value in the charge reaction / discharge reaction.

The rate of weight change during the discharge reaction excluding the loss of volatile electrolyte is +122.11 (± 0.08) μg / h, and +1.955 ± 0.005 electrons per oxygen molecule react. It turned out that oxygen was fixed. This value was one to two orders of magnitude more accurate than the method described in Non-Patent Document 1. From this, it was shown that the battery characteristics of the metal-air battery can be evaluated with high accuracy by using the evaluation device of the present invention.

Similarly, the weight change rate during the charging reaction (however, at the initial stage of charging start) excluding the loss of volatilization of the electrolytic solution is -114.50 (± 0.08) μg / h, and -2. It was found that 109 ± 0.006 electrons reacted and oxygen was released. Looking at FIG. 20, the weight of the lithium ion battery decreased linearly due to oxygen release at the initial stage of charging, but the weight decreased remarkably in the latter half of charging, showing a weight loss equal to or greater than the fixed amount of oxygen. This suggests that the gas was released due to the decomposition and deterioration of the electrolyte and the electrode material of the lithium-air battery.

[Example 4]
In Example 4, the evaluation device constructed in Example 1 was used to evaluate the battery characteristics (multiple cycles of rest, discharge, rest, and charge) of the lithium-air battery while flowing pure oxygen into the housing.

FIG. 21 is a diagram showing a weight measurement condition setting screen of Example 4.

The battery characteristics of the lithium-air battery were evaluated under the weight measurement conditions shown in FIG. 6 and the charge / discharge characteristic measurement conditions shown in FIG. As the evaluation items of the battery characteristics, the calculation of the electrolytic solution volatilization rate shown in FIG. 9, the calculation of the weight change amount due to the charge reaction / discharge reaction, the calculation of the number of electrons due to the charge reaction / discharge reaction, and the calculation of the capacitance are selected. bottom. The time interval of the electrolyte volatilization rate is 50 hours, the amount of weight change due to the charge reaction / discharge reaction is performed every time the weight is measured, and the time interval for calculating the number of electrons associated with the charge reaction / discharge reaction is every 30 seconds. rice field. The results are shown in FIGS. 22 to 25.

FIG. 22 is a diagram showing the results of the battery characteristics of the lithium-air battery of Example 4.
FIG. 23 is a diagram showing another result of the battery characteristics of the lithium-air battery of Example 4.

According to FIG. 22, the volatilization rate of the electrolytic solution at the time of the first rest is −5.36 (± 0.07) μg / h, and it depends on the discharge reaction by performing a plurality of cycles of rest, discharge, rest, and charge. It was found that the weight of the lithium-ion battery was reduced as a whole while repeating the weight increase and the weight decrease due to the charging reaction. This suggests that in addition to the weight loss due to the volatilization of the electrolytic solution, the outgassing due to the decomposition and deterioration of the electrolytic solution and the electrode material has a great influence. Although FIG. 22 shows only the electrolyte volatilization rate at the first rest, the electrolyte volatilization rate at all rests is actually calculated.

The upper part of FIG. 23 shows the amount of weight change due to the charge reaction / discharge reaction calculated from the electrolyte volatilization rate of FIG. 22. In the middle of FIG. 23, the weight change rate is shown in the charge reaction / discharge reaction calculated from the amount of weight change accompanying the charge reaction / discharge reaction. The lower part of FIG. 23 shows the number of reaction electrons calculated from the weight change rate and the current value in the charge reaction / discharge reaction.

Focusing on the number of reacted electrons during the charging reaction, the number of electrons deviated significantly from the ideal value (-2) in the latter half of the cycle, suggesting that the gas was released due to the decomposition and deterioration of the electrolyte and the electrode material.

FIG. 24 is a diagram showing another result of the battery characteristics of the lithium-air battery of Example 4.
FIG. 25 is a diagram showing another result of the battery characteristics of the lithium-air battery of Example 4.

FIG. 24 is an enlarged view of a part of FIG. 23. According to FIG. 24, it can be seen that the weight is changed according to the start / stop of charging / discharging, and the charging / discharging reaction is accurately tracked.

However, according to FIG. 25, a deviation of about ten minutes was observed between the start of discharge and the start of weight change. The capacitance of 0.2 mAh was calculated from the current value and the time during this deviation period. It was found that the lithium-air battery used in Example 4 was discharged by this capacitance. This capacitance was in good agreement with the capacitance (0.2 mAh) estimated from the voltage drop rate, and was a reliable value.

By using the metal-air battery evaluation device of the present invention, minute weight changes of the metal-air battery can be continuously measured for a long period of time. Therefore, among the battery reactions at the air electrode, the reaction efficiency of oxygen and electrons taken into the cell Can be accurately measured over a long period of time over multiple charge / discharge cycles. In addition, it is possible to measure and evaluate the volatilization rate of the electrolytic solution from the change in the weight of the cell when there is no current (rest). In addition to the metal-air battery, such an evaluation device can also evaluate the absorption / discharge characteristics of materials that exchange with external gas.

100 Evaluation device 110 Weight measuring unit 120 Stage 130 Elevating unit 140 Housing 150 Charging / discharging characteristic measuring unit 160 Control unit 170 Gas intake port 180 Gas exhaust port 190 Temperature detection unit

Claims (29)

1. An evaluation device that evaluates the battery characteristics of metal-air batteries.
   A weight measuring unit that measures the weight of the metal-air battery,
   An elevating part that is provided with a stage for mounting the metal-air battery and raises and lowers the stage,
   A housing that houses at least the weight measuring unit and the metal-air battery,
   A charge / discharge characteristic measuring unit that measures the charge / discharge characteristics of the metal-air battery,
   It is provided with a control unit that controls the operation of the elevating unit, the weight measuring unit, and the charge / discharge characteristic measuring unit, and evaluates the battery characteristics of the metal-air battery.
   The control unit
   A measurement control unit that raises and lowers the stage of the elevating unit, executes measurement by the weight measuring unit and the charging / discharging characteristic measuring unit, and acquires the weight change amount and charging / discharging characteristics of the metal-air battery.
   An evaluation device including a calculation / evaluation unit that calculates / evaluates the battery characteristics of the metal-air battery based on the weight change amount and the charge / discharge characteristics acquired by the measurement control unit.
2. The calculating and evaluation unit, the change in weight at time _{t r} during rest of the charge and discharge characteristics Wt _r and time _{t r0 (However, t r>} t _r0) weight change amount difference Wt of the change in weight _{Wt r0} of dividing the _r -wt _r0 by the time difference _t r _{-t r0,} further comprising an electrolyte evaporation rate calculation unit for calculating an electrolyte volatilization rate _{((Wt r -Wt r0) /} (t r -t r0)), wherein Item 1. The evaluation device according to item 1.
3. The calculation / evaluation unit estimates the volatilization of the electrolytic solution at the _{time t d from the amount of change in weight at the time t d} during the discharge of the charge / discharge characteristics using the volatilization rate of the electrolytic solution in the rest immediately before the discharge. The evaluation device according to claim 2, further comprising a discharge weight change amount calculation unit that reduces the amount and calculates the weight change amount due only to the discharge reaction.
4. The calculation / evaluation unit divides the amount of weight change due only to the discharge reaction _{of the time interval Δt d} during discharge of the charge / discharge characteristics calculated by the discharge weight change amount calculation unit by the _{time interval Δt d.} , The number of reaction electrons for calculating the weight change rate, dividing the current value used for measuring the charge / discharge characteristics by the weight change rate, and calculating the number of electrons reacting with the air absorbed in the metal air battery. The evaluation device according to claim 3, further comprising a calculation unit.
5. The calculation / evaluation unit estimates the volatilization of the electrolyte at _{time t c from the amount of change in weight at time t c} during charging of the charge / discharge characteristics using the volatilization rate of the electrolyte in the rest immediately before charging. The evaluation device according to any one of claims 2 to 4, further comprising a charge weight change amount calculation unit that reduces the amount and calculates the weight change amount due only to the charge reaction.
6. The calculation / evaluation unit divides the amount of weight change due only to the charging reaction _{of the time interval Δt c} during charging of the charge / discharge characteristics calculated by the charge weight change amount calculation unit by the _{time interval Δt c.} , The reaction to calculate the weight change rate, divide the current value used for measuring the charge / discharge characteristics by the weight change rate, and calculate the number of electrons required to discharge the air fixed to the metal-air battery. The evaluation device according to claim 5, further comprising an electron number calculation unit.
7. The calculation / calculation unit calculates the capacitance from the time ΔT required for the weight change to occur after the start of discharge of the charge / discharge characteristics and the current value flowing during the time ΔT. The evaluation device according to any one of claims 1 to 6, further comprising.
8. The evaluation device according to any one of claims 1 to 7, wherein the control unit further includes a display unit that displays the result of the calculation / evaluation unit.
9. The evaluation device according to any one of claims 1 to 8, further comprising a temperature detection unit in the housing.
10. The evaluation device according to any one of claims 1 to 9, further comprising an atmospheric pressure detection unit in the housing.
11. The evaluation device according to claim 9 or 10, wherein the control unit further includes a weighing value correction unit that corrects a weighing value by the weight measuring unit with a sensitivity drift value of the weight measuring unit.
12. The evaluation device according to any one of claims 1 to 11, wherein the housing includes a gas air supply port and a gas exhaust port.
13. The evaluation device according to any one of claims 1 to 12, further comprising a temperature control device for holding the temperature inside the housing.
14. A method for evaluating the battery characteristics of metal-air batteries.
    The arrangement of the metal-air battery at the measurement position of the weight measuring unit and the separation of the metal-air battery from the measurement position are repeated, and the weight of the metal-air battery is repeatedly measured.
    At the same time as the repeated measurement of the weight, the charge / discharge characteristics of the metal-air battery are measured.
    To calculate and evaluate the battery characteristics of the metal-air battery based on the weight change amount obtained by the repeated measurement and the charge / discharge characteristics obtained by measuring the charge / discharge characteristics. A method that includes and.
15. The calculation and evaluation that is, the change in weight at time _{t r} during rest of the charge and discharge characteristics Wt _r and time _{t r0 (However, t r>} t _r0) the change in weight difference between the change in weight _{Wt r0} of dividing the Wt _r -wt _r0 by the time difference _t r _{-t r0,} further comprising calculating the electrolyte volatilization rate _{((Wt r -Wt r0) /} (t r -t r0)), in claim 14 The method described.
16. The calculation / evaluation is an electrolytic solution at the _{time t d estimated from the amount of change in weight at the time t d} during the discharge of the charge / discharge characteristics and the volatilization rate of the electrolytic solution in the rest immediately before the discharge. The method of claim 15, further comprising reducing the amount of volatilization and calculating the amount of weight change due solely to the discharge reaction.
17. The calculation / evaluation is to calculate the weight change rate by dividing the amount of weight change caused only by the discharge reaction _{of the time interval Δt d} during discharge of the calculated charge / discharge characteristics by the _{time interval Δt d.} 16 of the invention, further comprising dividing the current value used for measuring the charge / discharge characteristics by the weight change rate to calculate the number of electrons reacting with the air absorbed by the metal air battery. The method described in.
18. The calculation / evaluation is an electrolytic solution at the _{time t c estimated from the amount of change in weight at the time t c} during charging of the charge / discharge characteristics using the electrolytic solution volatilization rate in the rest immediately before the charge. The method of any of claims 15-17, further comprising reducing the amount of volatilization and calculating the amount of weight change due solely to the charging reaction.
19. The calculation / evaluation is to calculate the weight change rate by dividing the amount of weight change caused only by the charging reaction _{of the time interval Δt c} during charging of the calculated charge / discharge characteristics by the _{time interval Δt c.} Further, the present invention further includes calculating the number of electrons required for discharging the air fixed to the metal-air battery by dividing the current value used for measuring the charge / discharge characteristics by the weight change rate. Item 18. The method according to Item 18.
20. The calculation / evaluation further includes calculating the capacitance from the time ΔT required for the weight change to occur after the start of discharge of the charge / discharge characteristics and the current value flowing during the time ΔT. The method according to any one of claims 14 to 19.
21. Prior to the repeated measurement,
    The placement of the immutable weight product at the measurement position of the weight measuring unit and the separation of the immutable weight product from the measurement position are repeated, and the weight of the immutable weight product is repeatedly measured.
    Simultaneously with the repeated measurement of the weight of the immutable weight product, the temperature change and / or the atmospheric pressure change in the measurement environment can be measured.
    Determining whether the weighed value of the immutable weight product fluctuates with the temperature change and / or the atmospheric pressure change.
    If it is determined that the weight is fluctuating in the above determination, the weighing value is corrected by the sensitivity drift value of the weight measuring unit, and if it is determined that the weighing value is not fluctuating in the above determination, the weighing value is not corrected. The method according to any one of claims 14 to 20, further comprising.
22. The method according to any one of claims 14 to 21, further comprising flowing an atmosphere control gas into the measurement environment prior to the repeated measurement.
23. A program that evaluates the battery characteristics of metal-air batteries.
    A function of repeatedly measuring the weight of the metal-air battery by repeatedly arranging the metal-air battery at the measurement position of the weight measuring unit and separating the metal-air battery from the measuring position.
    A function to measure the charge / discharge characteristics of the metal-air battery at the same time as the repeated measurement of the weight,
    A function of calculating and evaluating the battery characteristics of the metal-air battery based on the weight change amount obtained by the repeated measurement and the charge / discharge characteristics obtained by measuring the charge / discharge characteristics. A program that makes a computer realize.
24. The calculation and evaluation functions, the change in weight at time _{t r} during rest of the charge and discharge characteristics Wt _r and time _{t r0 (However, t r>} t _r0) the change in weight difference between the change in weight _{Wt r0} of dividing the Wt _r -wt _r0 by the time difference _t r _{-t r0,} further comprising the function of calculating the electrolyte volatilization rate _{((Wt r -Wt r0) /} (t r -t r0)), according to claim 23 Program.
25. The function of calculating and evaluating the electrolytic solution at the _{time t d estimated from the amount of change in the weight of the electrolytic solution at the time t d} during the discharge of the charge / discharge characteristics using the volatilization rate of the electrolytic solution in the rest immediately before the discharge. 24. The program of claim 24, further comprising the function of reducing the amount of volatilization and calculating the amount of weight change due solely to the discharge reaction.
26. The calculation / evaluation function calculates the weight change rate by dividing the amount of weight change caused only by the discharge reaction _{of the time interval Δt d} during discharge of the calculated charge / discharge characteristics by the _{time interval Δt d.} 25. The claim 25 further includes a function of dividing the current value used for measuring the charge / discharge characteristics by the weight change rate and calculating the number of electrons reacting with the air absorbed by the metal air battery. The method described.
27. The function of calculating and evaluating the electrolytic solution at the _{time t c estimated from the amount of change in weight at the time t c} during charging of the charge / discharge characteristics using the electrolytic solution volatilization rate in the rest immediately before the charge. The program according to any of claims 24 to 26, further comprising the function of reducing the amount of volatilization and calculating the amount of weight change due only to the charging reaction.
28. The calculation / evaluation function calculates the weight change rate by dividing the amount of weight change caused only by the charging reaction _{of the time interval Δt c} during charging of the calculated charge / discharge characteristics by the _{time interval Δt c.} The claim further includes a function of dividing the current value used for measuring the charge / discharge characteristics by the weight change rate and calculating the number of electrons required for discharging the air fixed to the metal-air battery. 27.
29. The function of calculating and evaluating further includes a function of calculating the capacitance from the time ΔT required for the weight change to occur after the start of discharging the charge / discharge characteristics and the current value flowing during the time ΔT. , The program according to any one of claims 23 to 28.

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