JP2014212056A - Deterioration determination device and deterioration determination method of secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine the degree of deterioration in a secondary battery without incurring an increase in the size of the secondary battery and degradation in the battery characteristics thereof.SOLUTION: A charger 1 is configured in such a manner that the degree of deterioration in a secondary battery 10 in which a positive electrode 11, a negative electrode 12 and a reference electrode 13 are stored together with an electrolytic solution in a container can be determined. The charger 1 includes: a storage section 6 for storing reference data D0 for determination that enables a mutual relationship between: degree of deterioration in the secondary battery 10; a potential difference between the positive electrode 11 and the negative electrode 12; and a potential difference between the positive electrode 11 and the reference electrode 13 to be identified; a measuring section 3 for performing a measurement processing for measuring each of a "first potential difference" between the positive electrode 11 and the negative electrode 12 and a "second potential difference" between the positive electrode 11 and the reference electrode 13; and a control section 7 for making the measuring section 3 measure the "first potential difference" and the "second potential difference" and identifying the degree of the deterioration in the second battery 10 based on the measured "first potential difference" and the measured "second potential difference" and the reference data D0 for determination.

Description

  The present invention relates to a secondary battery deterioration determination device and a secondary battery deterioration determination method for determining a deterioration state of a secondary battery in which a positive electrode, a negative electrode, and a reference electrode are contained in a container together with an electrolytic solution.

  Today, lithium-ion secondary batteries are widely used as power sources for various electronic devices and electric machines because the battery performance does not deteriorate even when recharging is performed and the energy density is high. However, even in the lithium ion secondary battery, the battery capacity (the amount of electric power that can be released from the fully charged state) is reduced due to deterioration as charging and discharging are repeated a plurality of times. Therefore, in electronic devices and electric machines that use this type of secondary battery as a power source, it is necessary to replace the deteriorated secondary battery with a new secondary battery in order to avoid unintended loss of the power source. is there. For this reason, it is necessary to accurately determine the degree of deterioration of the secondary battery.

  For example, Japanese Patent Laid-Open No. 2012-79582 diagnoses the degree of deterioration of a secondary battery that includes four electrodes, a positive electrode, a negative electrode, a reference electrode, and a counter electrode (determining the degree of deterioration). A degradation degree diagnosis method is disclosed. In this deterioration degree diagnosis method, first, using the positive electrode in the secondary battery as a working electrode, the impedance of the positive electrode (positive electrode and reference electrode) is determined by the AC impedance method using the positive electrode, the reference electrode, and the counter electrode. The impedance of the positive electrode (charge transfer resistance) is specified based on the measured impedance. Next, in the same manner as the above-described treatment for the positive electrode, impedance measurement is performed using the negative electrode as a working electrode, and the resistance of the negative electrode is specified.

  Subsequently, the degree of deterioration of the secondary battery is diagnosed based on the identified positive electrode resistance and negative electrode resistance (charge transfer resistance). In this case, in this type of secondary battery, the resistance of the positive electrode and the resistance of the negative electrode tend to increase as the deterioration progresses. Therefore, it is possible to diagnose the deterioration state of the positive electrode by comparing the resistance of the positive electrode in the secondary battery that has not deteriorated with the resistance of the positive electrode specified in the secondary battery to be diagnosed, and the deterioration occurs. The deterioration state of the negative electrode can be diagnosed by comparing the resistance of the negative electrode in the non-rechargeable secondary battery with the resistance of the negative electrode specified in the secondary battery to be diagnosed. Thereby, the degree of deterioration of the secondary battery is diagnosed.

JP 2012-79582 A (page 4-11, Fig. 1-4)

  However, the conventional degradation degree diagnosis method has the following problems. That is, in the conventional degradation degree diagnosis method, the impedance of the positive electrode is determined by measuring the impedance of the positive electrode by the AC impedance method using the positive electrode as the working electrode, and the impedance of the negative electrode is determined by the AC impedance method using the negative electrode as the working electrode. A method of diagnosing the degree of deterioration of the secondary battery by measuring the resistance of the negative electrode and specifying the resistance of the negative electrode is employed. In this case, the positive electrode impedance and the negative electrode impedance measured by the AC impedance method are greatly different depending on the size of the reference electrode (the electrode area of the reference electrode). The amount of change in impedance due to the degree of degradation (difference in positive electrode resistance and negative electrode resistance) is reduced. Therefore, in a secondary battery with a small reference electrode, it is difficult to accurately specify the resistance of the positive electrode and the resistance of the negative electrode based on the measured impedance.

  However, when the reference electrode is enlarged in order to accurately diagnose the degree of deterioration, it has the same battery capacity as the large reference electrode that does not directly contribute to charge / discharge is accommodated in the battery container. This leads to a larger size than other secondary batteries. Moreover, in a secondary battery having a configuration in which a reference electrode is disposed between a sheet-like positive electrode and a sheet-like negative electrode, as in the secondary battery disclosed in the above prior art document, the positive electrode, the negative electrode, When a large reference electrode is disposed between the two, the battery reaction (migration of lithium ions) occurring between the positive electrode and the negative electrode is hindered by the large reference electrode, and the battery characteristics may deteriorate. For this reason, it is difficult to enlarge the reference electrode, and there is a problem that it is difficult to accurately diagnose the degree of deterioration of the secondary battery in the conventional deterioration degree diagnosis method.

  The present invention has been made in view of such problems, and a secondary battery deterioration determination device capable of accurately determining the degree of deterioration without incurring an increase in the size of a secondary battery or deterioration in battery characteristics. And it aims at providing the degradation determination method of a secondary battery.

  In order to achieve the above-mentioned object, the secondary battery deterioration determination device according to claim 1 has a degree of deterioration for a secondary battery configured such that a positive electrode, a negative electrode, and a reference electrode are housed in a container together with an electrolyte. A secondary battery deterioration determination device configured to be capable of determination, wherein the secondary battery has a degree of deterioration, a potential difference between the positive electrode and the negative electrode, and a potential difference between the positive electrode and the reference electrode. A storage unit that stores deterioration determination information that can specify the first potential difference, and a first potential difference between the positive electrode and the negative electrode, and a measurement process that measures a second potential difference between the positive electrode and the reference electrode And measuring the first potential difference and the second potential difference in the secondary battery to be determined by controlling the measurement unit to execute the measurement process, and measuring the measured potential And a processing unit for identifying the degree of deterioration of the secondary battery of the determination target based on the first potential difference and the said deterioration determining information stored in the storage unit and the second potential difference.

  The secondary battery deterioration determination method according to claim 2 is a secondary battery for determining a degree of deterioration for a secondary battery configured such that a positive electrode, a negative electrode, and a reference electrode are housed in a container together with an electrolyte. Deterioration determination information, the deterioration determination information capable of specifying the degree of deterioration of the secondary battery, the potential difference between the positive electrode and the negative electrode, and the potential difference between the positive electrode and the reference electrode. And performing a measurement process for measuring a first potential difference between the positive electrode and the negative electrode and a second potential difference between the positive electrode and the reference electrode in the secondary battery to be determined, Based on the first potential difference, the second potential difference, and the deterioration determination information, the degree of deterioration of the determination target secondary battery is specified.

  In the secondary battery deterioration determination apparatus according to claim 1 and the secondary battery deterioration determination method according to claim 2, the first potential difference between the positive electrode and the negative electrode in the secondary battery to be determined, the positive electrode, and the reference A measurement process for measuring each of the second potential difference between the electrodes, the measured first potential difference and the second potential difference, the degree of deterioration of the secondary battery, the potential difference between the positive electrode and the negative electrode, and The degree of deterioration of the determination target secondary battery is specified based on the deterioration determination information that can specify the correlation between the potential difference between the positive electrode and the reference electrode.

  Therefore, according to the deterioration determination device for a secondary battery according to claim 1 and the deterioration determination method for a secondary battery according to claim 2, the secondary battery including a reference electrode having a sufficiently large reference electrode capable of measuring the positive electrode potential is provided. As long as the battery is a secondary battery, by measuring the positive electrode potential and the battery voltage, the degree of deterioration of the secondary battery can be accurately determined based on the measurement result and the information for deterioration determination. For this reason, according to the deterioration determination device and the deterioration determination method, it is not necessary to mount a large reference electrode in order to accurately determine the degree of deterioration, so that the degree of deterioration can be accurately measured. Thus, it is possible to provide a secondary battery having good battery characteristics and being sufficiently miniaturized.

2 is a configuration diagram showing configurations of a charger 1 and a secondary battery 10. FIG. Potential difference between the positive electrode 11 and the negative electrode 12 for the secondary battery 10 that has not deteriorated, the secondary battery 10 in which the battery capacity has been reduced by 10%, and the secondary battery 10 in which the battery capacity has been reduced by 20%. It is explanatory drawing for demonstrating the relationship between (battery voltage) and the electrical potential difference between the positive electrode 11 and the reference electrode 13. FIG. Potential difference between the positive electrode 11 and the negative electrode 12 for the secondary battery 10 that has not deteriorated, the secondary battery 10 in which the battery capacity has been reduced by 10%, and the secondary battery 10 in which the battery capacity has been reduced by 20%. FIG. 10 is another explanatory diagram for explaining a relationship between (battery voltage) and a potential difference between the positive electrode 11 and the reference electrode 13.

  Hereinafter, embodiments of a secondary battery deterioration determination device and a secondary battery deterioration determination method will be described with reference to the accompanying drawings.

  The charger 1 shown in FIG. 1 is an example of a “secondary battery deterioration determination device” configured to be able to determine the degree of deterioration of the secondary battery 10 according to a “secondary battery deterioration determination method” described later. , Power supply unit 2, measurement unit 3, operation unit 4, display unit 5, storage unit 6, and control unit 7. In this case, the secondary battery 10 is a lithium ion secondary battery that is an example of a “secondary battery”, and the three electrodes of the positive electrode 11, the negative electrode 12, and the reference electrode 13 are accommodated in the battery container together with the electrolyte. Configured.

  Specifically, the positive electrode 11 includes, as an example, a coating liquid obtained by mixing a conductive additive such as a lithium-containing oxide of transition metals such as cobalt, nickel, and manganese, carbon, and a binder with aluminum, an aluminum alloy, or the like. The electrode layer is formed by applying and curing on the surface of the support composed of the metal (conductor), and is formed into a sheet shape as a whole. The negative electrode 12 is made of a coating liquid obtained by mixing granular (scale-like, fibrous, spherical, pseudo-spherical, massive and powdery) graphite (graphite), amorphous carbon, and the like with a binder. An electrode layer is formed by applying and curing on the surface of a support made of a metal (conductor) such as a metal sheet, and is formed into a sheet shape as a whole. Further, the reference electrode 13 has an electrode layer formed by applying a coating liquid in which lithium or a lithium alloy is dispersed on the surface of a support made of a metal (conductor) such as nickel or stainless steel and curing the coating liquid. As a whole, it is formed into a sheet shape. As an example, the internal structure of the secondary battery 10 is the same as that of the secondary battery to be diagnosed in the conventional degradation degree diagnosis method, and thus illustration and detailed description thereof are omitted.

In this case, the inventor has found that the potential difference between the positive electrode 11 and the reference electrode 13, that is, the potential of the positive electrode 11 with respect to the reference electrode 13, as the deterioration progresses (the battery capacity decreases). (In the present example in which the reference electrode 13 includes an electrode layer formed of lithium, a lithium alloy, or the like, the potential based on “Li ⁺ / Li: hereinafter, also referred to as“ positive electrode potential ”) is high. I found that this phenomenon occurs.

  Specifically, as shown in FIGS. 2 and 3, for example, when the potential difference between the positive electrode 11 and the negative electrode 12 (that is, the battery voltage) is 3.0 V, the deterioration occurs. In the secondary battery 10 having a battery capacity of 100% (hereinafter also referred to as “secondary battery 10 having a capacity of 100%”), the positive electrode potential is 3.4918 V, whereas the battery is in a fully charged state due to deterioration. In the secondary battery 10 whose capacity is reduced by 10% (hereinafter also referred to as “secondary battery 10 having a capacity of 90%”), the positive electrode potential is 3.7518 V, and the battery capacity in the fully charged state is reduced by 20% due to deterioration. In the secondary battery 10 (hereinafter, also referred to as “secondary battery 10 having a capacity of 80%”), the positive electrode potential was confirmed to be 3.7952V. Similarly, when focusing on the positive electrode potential when the battery voltage is 4.0 V, the secondary battery 10 with a capacity of 100% has a positive electrode potential of 4.0648 V, whereas the secondary battery with a capacity of 90%. 10, the positive electrode potential was 4.0700 V, and in the secondary battery 10 having a capacity of 80%, it was confirmed that the positive electrode potential was 4.0872 V.

  Such a phenomenon is caused by repeating charging and discharging a plurality of times, whereby metallic lithium is deposited on the surface of the negative electrode 12, or SEI (Solid Electrolyte Interface) is caused by a chemical reaction in the electrolyte (for example, the interface of the negative electrode 12). Is formed (irreversible reaction due to charging / discharging), and the amount of lithium ions that can move between the positive electrode 11, the electrolytic solution, and the negative electrode 12 is reduced. It is considered that the positive electrode potential is increased by reducing the amount of ions taken into the substrate. Therefore, as will be described later, in the deterioration determination method using the charger 1, the degree of deterioration of the secondary battery 10 is determined by measuring the potential of the positive electrode 11 with respect to the reference electrode 13 and comparing it with a reference value.

  On the other hand, the power supply unit 2 applies a charging voltage between the positive electrode 11 and the negative electrode 12 of the secondary battery 10 according to the control of the control unit 7 during the charging process. The measurement unit 3 is an example of a “measurement unit” and includes a voltage measurement circuit and a connection switching unit (not shown), and a potential difference between the positive electrode 11 and the negative electrode 12 of the secondary battery 10 according to the control of the control unit 7. (Battery voltage: an example of “first potential difference”) is measured and a measured value DV1 is output, and a potential difference between the positive electrode 11 and the reference electrode 13 of the secondary battery 10 (positive electrode potential: “second potential difference”) ) Is measured and a measured value DV2 is output. In addition, during the charging process, the measurement unit 3 measures a potential difference (negative electrode potential) between the negative electrode 12 and the reference electrode 13 of the secondary battery 10 in addition to the above-described potential difference, and outputs a measured value DV3. In this case, according to the control of the control unit 7, the connection switching unit described above connects and disconnects the positive electrode 11 to the high potential side connection unit in the voltage measurement circuit, and disconnects the negative electrode 12 from the low potential side connection unit in the voltage measurement circuit. The connection of the reference electrode 13 to either the high potential side connection portion or the low potential side connection portion is switched.

  The operation unit 4 includes a charge process start / stop switch for starting / stopping the charge process and a determination process start / stop switch for starting / stopping the deterioration state determination process, and sends an operation signal to the control unit 7 according to the switch operation. Output. The display unit 5 displays a message indicating that the charging process is in progress (not shown) and the determination result of the deterioration state determination process (not shown) under the control of the control unit 7. The storage unit 6 is an example of a “storage unit”, and is used for determination that can specify the correlation between the degree of deterioration of the secondary battery 10 (specifically, “battery capacity”), the battery voltage, and the positive electrode potential. Reference data D0 (an example of “degradation determination information”) is stored. In this case, for the determination reference data D0, as an example, measurement processing for the secondary battery 10 having a capacity of 100%, the secondary battery 10 having a capacity of 90%, and the secondary battery 10 having a capacity of 80% is executed. In advance.

  Specifically, as an example, as shown in FIGS. 2 and 3, for a secondary battery 10 having a capacity of 100%, the “battery voltage (potential difference between the positive electrode 11 and the negative electrode 12)” is 3.0 V, “When measuring the positive electrode potential (potential difference between the positive electrode 11 and the reference electrode 13) at each voltage value of 3.2V, 3.4V, 3.6V, 3.8V, 4.0V and 4.2V, Based on each measured “positive electrode potential”, the above-described voltage values of “battery voltage” are complemented to obtain “positive electrode potential for each battery voltage” indicated by a solid line in FIG. Similarly, for the secondary battery 10 having a capacity of 90%, the “positive electrode potential for each battery voltage” shown by the one-dot chain line in FIG. 2 is obtained, and for the secondary battery 10 having the capacity of 80%, the two-dot chain line in FIG. The “positive electrode potential for each battery voltage” is obtained. Next, determination reference data D0 is generated based on the “positive electrode potential for each battery voltage” for each secondary battery 10.

  The determination reference data D0 can also be generated in the charger 1, but in this example, as an example, the measurement (not shown) by the manufacturer of the secondary battery 10 (or the manufacturer of the charger 1). It is assumed that determination reference data D0 generated in advance based on the measurement result measured using the apparatus is stored in the storage unit 6. Further, in this example, in order to facilitate understanding of the “secondary battery deterioration determination device” and the “secondary battery deterioration determination method”, the three types of secondary batteries 10 described above were obtained. “Positive electrode potential for each battery voltage” is used as the determination reference data D0. In addition to the three types of secondary batteries 10 described above, for example, the secondary battery 10 having a capacity of 95% and the secondary battery having a capacity of 85% are used. The determination reference data D0 can be generated in consideration of the “positive electrode potential for each battery voltage” obtained for the battery 10.

  The control unit 7 controls the charger 1 as a whole. Specifically, the control unit 7 controls the power supply unit 2 to apply a charging voltage between the positive electrode 11 and the negative electrode 12 of the secondary battery 10 during the charging process. In addition, the control unit 7 controls the measurement unit 3 to measure the potential difference (negative electrode potential) between the negative electrode 12 and the reference electrode 13 during the charging process, and the measured potential difference (measured value DV3) The occurrence of overcharging is avoided by controlling the application of the charging voltage by the power supply unit 2 so as not to fall below a predetermined lower limit value. Furthermore, the control unit 7 controls the measurement unit 3 to measure the potential difference (battery voltage) between the positive electrode 11 and the negative electrode 12 during the charging process, and the charging process is performed based on the measured voltage value (measured value DV1). When the measured value DV1 becomes a fully charged state defined in advance and the measured value DV3 falls to the above lower limit value (overcharge) The power supply unit 2 is controlled to stop the application of the charging voltage.

  The control unit 7 corresponds to a “processing unit” and executes a deterioration determination process for the secondary battery 10. Specifically, as an example, when the start of the deterioration determination process is instructed by the operation of the operation unit 4, the control unit 7 controls the measurement unit 3 to execute the measurement process to determine the secondary battery to be determined. 10, the potential difference between the positive electrode 11 and the negative electrode 12 (battery voltage: measured value DV1) and the potential difference between the positive electrode 11 and the reference electrode 13 (positive electrode potential: measured value DV2) are measured. Further, the control unit 7 determines the degree of deterioration of the secondary battery 10 to be determined based on the measured values DV1 and DV2 measured by the measuring unit 3 and the determination reference data D0 stored in the storage unit 6. Identify.

  In order to determine the degree of deterioration of the secondary battery 10 by the charger 1, first, as shown in FIG. 1, the positive terminal, the negative terminal, and the reference electrode terminal in the secondary battery 10 to be determined are determined by the measuring unit 3. Connect to the connection switching unit. Next, the determination process start / stop switch of the operation unit 4 is operated. At this time, the control unit 7 first controls the measurement unit 3 according to the operation signal from the operation unit 4, and controls the potential difference (battery voltage) between the positive electrode 11 and the negative electrode 12 and the positive electrode 11 and the reference electrode 13. The potential difference (positive electrode potential) is measured.

  At this time, in the measurement unit 3, first, the connection switching unit connects the positive electrode 11 to the high potential side connection unit of the voltage measurement circuit and connects the negative electrode 12 to the low potential side connection unit of the voltage measurement circuit, The reference electrode 13 is switched to a state where it is not connected to any connection part. Next, the voltage measurement circuit measures the potential difference (battery voltage) between the positive electrode 11 (high potential side connection portion) and the negative electrode 12 (low potential side connection portion), and the measured value DV1 indicating the measured battery voltage is controlled by the control unit. 7 is output. Subsequently, while the connection switching unit maintains the state in which the positive electrode 11 is connected to the high potential side connection unit, the reference electrode 13 is connected to the low potential side connection unit, and the negative electrode 12 is connected to any connection unit. Switch to a state that is not done. Next, the voltage measurement circuit measures the potential difference (positive electrode potential) between the positive electrode 11 (high potential side connection portion) and the reference electrode 13 (low potential side connection portion), and controls the measured value DV2 indicating the measured battery voltage. Output to unit 7.

  Next, the control unit 7 determines the secondary battery to be determined connected to the measurement unit 3 based on the measurement values DV1 and DV2 output from the measurement unit 3 and the determination reference data D0 read from the storage unit 6. A degree of degradation of 10 is determined.

  At this time, as an example, when the measured value DV1 (battery voltage) output from the measuring unit 3 is 3.3V and the measured value DV2 (positive electrode potential) is 3.75V (the measured values DV1 and DV2 are shown in the figure). 2), the control unit 7 determines that the determination target secondary battery 10 has a battery capacity of about 90% based on both the measured values DV1 and DV2 and the determination reference data D0. It is determined (identified) that it is in a state (deteriorated state in which the battery capacity has decreased by about 10%), and the result of the determination (as an example, “This battery has a battery capacity decreased by about 10%”) Message) is displayed on the display unit 5 (not shown). Specifically, in this example, the measured value DV1 is 3.3V and the measured value DV2 is 3.75V, and the secondary battery 10 has a battery capacity of 90% (the battery capacity is 10%). The reference data D0 for determination (decreased deterioration state) are related to each other. For this reason, the control part 7 specifies that the state of the secondary battery 10 corresponding to this point A is a state in which the battery capacity is about 90%.

  As another example, when the measured value DV1 (battery voltage) output from the measuring unit 3 is 3.1V and the measured value DV2 (positive electrode potential) is 3.65V (the measured values DV1 and DV2 are shown in the figure). 2), the control unit 7 determines that the determination target secondary battery 10 has a capacity of 100% (based on both the measurement values DV1 and DV2 and the determination reference data D0). It is determined (identified) to be between a state in which no deterioration has occurred and a state in which the capacity is 90% (a state in which the battery capacity has deteriorated within a range of less than 10%). Is displayed on the display unit 5 (not shown). Specifically, in this example, the point B where the measured value DV1 is 3.1V and the measured value DV2 is 3.65V, the determination reference data D0 when the battery capacity is 100%, and the secondary battery 10 are The reference data D0 for determination in a state where the battery capacity is 90% are related to each other. Therefore, the control unit 7 determines that the state of the secondary battery 10 corresponding to this point B is an intermediate deterioration state between the state where no deterioration has occurred and the state where the battery capacity is 90%, that is, about 95. % Battery capacity is specified.

  As still another example, when the measured value DV1 (battery voltage) output from the measuring unit 3 is 3.4V and the measured value DV2 (positive electrode potential) is 3.80V (the measured values DV1 and DV2 are 2), the control unit 7 determines that the determination target secondary battery 10 has a capacity of 80% based on the measured values DV1 and DV2 and the determination reference data D0. (Deteriorated state when battery capacity is reduced by 20%) is determined (specified), and the result of the determination (for example, “This battery is about 20% less battery capacity” message) is displayed 5 (not shown). Specifically, in this example, the measured value DV1 is 3.4V and the measured value DV2 is 3.80V, and the secondary battery 10 has a battery capacity of 80% (the battery capacity is 20%). The reference data D0 for determination (decreased deterioration state) are related to each other. For this reason, the control part 7 specifies that the state of the secondary battery 10 corresponding to this point C is a state in which the battery capacity is about 80%.

  As shown in FIGS. 2 and 3, it was confirmed that the increase in the positive electrode potential according to the degree of deterioration of the secondary battery 10 is more noticeable as the battery voltage is lower. Therefore, the lower limit value of the battery voltage in the normal use state of the secondary battery 10 (for example, 3.0 V in the secondary battery 10 having the characteristics shown in both figures) and the upper limit value of the battery voltage (the battery voltage in the fully charged state, In the secondary battery 10 having the characteristics shown in both figures, the degree of deterioration of the determination-target secondary battery 10 by executing the above-described deterioration determination process at a battery voltage equal to or lower than an intermediate voltage of 4.2 V, for example. Can be determined more accurately. Thereby, the deterioration determination process is completed.

  In this case, as shown in FIGS. 2 and 3, in the secondary battery 10 having a capacity of 100% (secondary battery 10 without deterioration), the battery voltage is changed from 4.2V to 3.0V. The positive electrode potential changes greatly for each battery voltage. Therefore, in the secondary battery 10 having a capacity of 100%, a sufficient amount of ions are released from the active material of the positive electrode 11 into the electrolytic solution until the battery voltage is changed from 4.2 V to 3.0 V. I understand that.

  On the other hand, in the secondary battery 10 having a capacity of 90% (the secondary battery 10 having a battery capacity reduced by 10% due to deterioration), each battery is changed from a state of 4.2V to a state of about 3.6V. Although the positive electrode potential changes greatly for each voltage, when the battery voltage falls below 3.6 V, the amount of decrease in the positive electrode potential for each battery voltage decreases. Therefore, in the secondary battery 10 having a capacity of 90%, a sufficient amount of ions from the active material of the positive electrode 11 to the electrolyte solution until the battery voltage is changed from 4.2 V to about 3.6 V. Although released, when the battery voltage falls below 3.6 V, a sufficient amount of ions are released into the electrolyte due to the fact that a sufficient amount of ions do not remain in the active material of the positive electrode 11. It can be seen that it is impossible to supply a sufficient amount of power.

  Further, in the secondary battery 10 having a capacity of 80% (the secondary battery 10 having a battery capacity reduced by 20% due to deterioration), each battery is changed from a state of 4.2V to a state of about 3.6V. Although the positive electrode potential changes greatly for each voltage, when the battery voltage falls below 3.6 V, the positive electrode potential for each battery voltage hardly changes. Therefore, in the secondary battery 10 having a capacity of 80%, a sufficient amount of ions are contained in the electrolyte from the active material of the positive electrode 11 until the battery voltage is changed from 4.2 V to about 3.6 V. Although released, when the battery voltage falls below 3.6 V, there are almost no releasable ions remaining in the active material of the positive electrode 11, that is, a state where only a very small amount of power can be supplied. I understand.

  Therefore, a user who has seen the determination result by the charger 1 (in this example, the determination result displayed on the display unit 5), as an example, indicates that the determination-target secondary battery 10 has deteriorated to a capacity of 80%. When the determination is made, the secondary battery 10 is replaced with a new secondary battery 10 and mounted on an electronic device or the like. Thereby, the situation where the power loss which is not intended in the electronic device which uses the secondary battery 10 as a power supply arises is avoided.

  As described above, in the charger 1 and the deterioration determination method using the charger 1, the potential difference between the positive electrode 11 and the negative electrode 12 (battery voltage: measured value DV1: first potential difference) in the secondary battery 10 to be determined is , A measurement process for measuring the potential difference between the positive electrode 11 and the reference electrode 13 (positive electrode potential: measured value DV2: second potential difference) is performed, and the measured values DV1, DV2 measured and the secondary battery 10 Determination standard data D0 that can specify the degree of deterioration (battery capacity), the potential difference between the positive electrode 11 and the negative electrode 12 (battery voltage), and the potential difference between the positive electrode 11 and the reference electrode 13 (positive electrode potential). Based on the above, the degree of deterioration of the secondary battery 10 to be determined is specified.

  Therefore, according to the charger 1 and the method for determining the deterioration of the secondary battery by the charger 1, as long as it is a “secondary battery” having a “reference electrode” having a necessary and sufficient size capable of measuring the positive electrode potential. By measuring the positive electrode potential and the battery voltage, the degree of deterioration of the “secondary battery” can be accurately determined based on the measurement result and the determination reference data D0. Therefore, according to the charger 1 and the secondary battery deterioration determination method using the charger 1, it is not necessary to mount a large “reference electrode” to accurately determine the degree of deterioration. It is possible not only to measure the degree accurately, but also to provide a “secondary battery” having good battery characteristics and being sufficiently miniaturized.

  The configuration of the “secondary battery deterioration determination device” and the “secondary battery deterioration determination method” are not limited to the configuration of the charger 1 and the deterioration determination method by the charger 1. For example, for the “lithium ion secondary battery”, the configuration / method for determining the degree of deterioration has been described. For example, various “such as“ calcium ion secondary battery ”and“ aluminum ion secondary battery ” Even when a “secondary battery” is targeted, the degree of deterioration can be determined by the same configuration and method as in the above example. In addition, the configuration in which the “secondary battery deterioration determination device” is applied to the “charger” has been described as an example, but instead of such a configuration, a component for executing the charging process is not provided. The “secondary battery deterioration determination method” may be executed in the apparatus to determine the degree of deterioration of the determination target “secondary battery”.

DESCRIPTION OF SYMBOLS 1 Charger 2 Power supply part 3 Measuring part 6 Storage part 7 Control part 10 Secondary battery 11 Positive electrode 12 Negative electrode 13 Reference electrode D0 Reference data for determination DV1 to DV3 Measured value

Claims (2)

A secondary battery deterioration determination device configured to be capable of determining the degree of deterioration for a secondary battery configured by accommodating a positive electrode, a negative electrode, and a reference electrode together with an electrolyte in a container body,
A storage unit that stores deterioration determination information capable of specifying the degree of deterioration of the secondary battery, the potential difference between the positive electrode and the negative electrode, and the potential difference between the positive electrode and the reference electrode;
A measurement unit that performs a measurement process for measuring a first potential difference between the positive electrode and the negative electrode, and a second potential difference between the positive electrode and the reference electrode;
The measurement unit is controlled to execute the measurement process to measure the first potential difference and the second potential difference in the determination target secondary battery, respectively, and the measured first potential difference and the second potential difference are measured. A deterioration determination device for a secondary battery, comprising: a processing unit that specifies a degree of deterioration of the determination target secondary battery based on the potential difference of 2 and the deterioration determination information stored in the storage unit. A secondary battery deterioration determination method for determining the degree of deterioration for a secondary battery configured by accommodating a positive electrode, a negative electrode, and a reference electrode together with an electrolyte in a container body,
Obtaining deterioration determination information capable of specifying the degree of deterioration of the secondary battery, the potential difference between the positive electrode and the negative electrode, and the potential difference between the positive electrode and the reference electrode, and the determination target A measurement process is performed to measure a first potential difference between the positive electrode and the negative electrode and a second potential difference between the positive electrode and the reference electrode in a secondary battery, respectively, and the measured first potential difference and the measured A secondary battery deterioration determination method for specifying a degree of deterioration of the determination-target secondary battery based on a second potential difference and the deterioration determination information.

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