Degradation-state determination device for lithium metal battery, method for determining degradation state of lithium metal battery, and program

Abstract

To accurately detect degradation of a lithium metal battery.SOLUTION: A degradation-state determination device for a lithium metal battery includes: an acquisition unit configured to acquire an anode resistance value obtained by applying a voltage to a lithium metal battery having an anode containing lithium; and a determination unit configured to determine the degradation state of the lithium metal battery on the basis of the estimated thickness of the anode estimated from the anode resistance value and the relationship between the anode resistance value and the first reference value related to the thickness of the anode, the relationship being defined by a first map.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device for determining the state of deterioration of a lithium metal battery, a method for determining the state of deterioration of a lithium metal battery, and a program. [Background technology]

[0002] In recent years, research and development has been conducted to contribute to energy efficiency so that more people can have access to affordable, reliable, sustainable, and advanced energy. Regarding this technology, lithium metal batteries, which use lithium metal as a negative electrode, have attracted attention as a secondary battery. A lithium metal battery includes a positive electrode, a negative electrode having a metallic lithium layer, and an electrolyte disposed between the positive electrode and the negative electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2023 / 118960 [Patent Document 2] Japanese Patent Publication No. 2023-17581 [Patent Document 3] Japanese Patent Publication No. 2022-113377 Summary of the Invention [Problem to be solved by the invention]

[0004] In this technology, as lithium metal batteries are repeatedly charged and discharged, a solid electrolyte interphase (SEI) film is formed and grows on the metallic lithium layer of the negative electrode. As a result, as the thickness of the negative electrode increases, a load is placed on the lithium metal, raising concerns about deterioration that could lead to structural damage to the lithium metal battery.

[0005] The present invention has been made in consideration of the above circumstances, and one of its objects is to enable accurate detection of deterioration of lithium metal batteries, which in turn contributes to improved energy efficiency. [Means for solving the problem]

[0006] The device, method, and program for determining the state of deterioration of a lithium metal battery according to the present invention employ the following configuration. (1): A lithium metal battery degradation state determination device according to one embodiment of the present invention is a lithium metal battery degradation state determination device comprising: an acquisition unit that acquires resistance value information relating to the resistance value obtained by applying a voltage to a lithium metal battery having a negative electrode containing lithium; a first map that shows the relationship between the thickness of the negative electrode and the resistance value, which is created in advance; and a determination unit that determines the degradation state of the lithium metal battery based on the acquired resistance value information.

[0007] (2) In the above aspect (1), the acquisition unit acquires the resistance value information based on the current value of the current discharged from the lithium metal battery.

[0008] (3): In the above aspect (1), the judgment unit judges that the deterioration state of the lithium metal battery is in a state where it can be reused when the acquired resistance value is a resistance value at which the thickness of the negative electrode is equal to or less than a first reference value.

[0009] (4): In the above aspect (3), the judgment unit judges the deterioration state of the lithium metal battery further based on a second map created in advance that shows the relationship between the thickness of the positive electrode of the lithium metal battery and the resistance value, and if the acquired resistance value is a resistance value at which the thickness of the positive electrode is equal to or less than a second reference value, judges that the deterioration state of the lithium metal battery is in a state where it can be reused.

[0010] (5): In the above aspect (3) or (4), the lithium metal battery is a lithium metal battery mounted on a vehicle, and the acquisition unit acquires the resistance value obtained by applying an AC voltage to the lithium metal battery removed from the vehicle.

[0011] (6): In the above aspect (1), the lithium metal battery is a lithium metal battery mounted on a vehicle, and the acquisition unit acquires a resistance value obtained by applying an AC voltage to the lithium metal battery mounted on the vehicle.

[0012] (7): In the aspect of (1) above, the lithium metal battery is a lithium metal battery mounted on a vehicle, and the acquisition unit acquires a measurement result of measuring the current discharged from the lithium metal battery mounted on the vehicle at a timing after a predetermined time of 0.001 seconds or more and 1.0 seconds or less has elapsed, and acquires a preliminary judgment result that preliminarily judges the deterioration state of the lithium metal battery based on the measurement result, and the judgment unit preliminarily judges the deterioration state of the lithium metal battery based on the preliminary judgment result that preliminarily judges the deterioration state of the lithium metal battery based on the acquired measurement result.

[0013] (8): A method for determining the state of deterioration of a lithium metal battery according to one embodiment of the present invention is a method for determining the state of deterioration of a lithium metal battery, in which a computer acquires resistance value information regarding the resistance value obtained by applying a voltage to a lithium metal battery having a negative electrode containing lithium, and determines the state of deterioration of the lithium metal battery based on a first map created in advance that shows the relationship between the thickness of the negative electrode and the resistance value and the acquired resistance value information.

[0014] (9): A program according to one embodiment of the present invention is a program that causes a computer to acquire resistance value information regarding the resistance value obtained by applying a voltage to a lithium metal battery having a negative electrode containing lithium, and determine the state of deterioration of the lithium metal battery based on a first map that shows the relationship between the thickness of the negative electrode and the resistance value and the acquired resistance value information, which is created in advance. [Effects of the Invention]

[0015] According to aspects (1) to (9), the deterioration of the lithium metal battery can be detected with high accuracy. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing an example of a deterioration state determining device 100 according to a first embodiment. [Figure 2] 1 is a diagram showing an example of a lithium metal battery 10 mounted on a vehicle M. FIG. [Figure 3] 1 is a diagram showing a schematic diagram of changes in the negative electrode 12 when the lithium metal battery 10 is repeatedly charged and discharged. [Figure 4] FIG. 10 is a diagram showing an example of a visualized deterioration determination map 121. [Figure 5] FIG. 10 is a diagram showing an example of a visualized preliminary determination map 122. [Figure 6] 4 is a flowchart illustrating an example of processing performed by the determination device 100 of the first embodiment. [Figure 7] FIG. 2 is a block diagram showing an example of a degradation state determining device 200 according to a second embodiment. [Figure 8] FIG. 10 is a diagram showing an example of a visualized bipolar deterioration determination map 123. [Figure 9] 10 is a flowchart showing an example of processing performed by a determination device 200 according to the second embodiment. [Figure 10] 10 is a graph showing an example of the relationship between impedance mainly derived from resistance values ​​and impedance mainly derived from capacitor components. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the drawings, an embodiment of a lithium metal battery degradation state determination device, a lithium metal battery degradation state determination method, and a program according to the present invention will be described.

[0018] First Embodiment A first embodiment will be described. FIG. 1 is a block diagram showing an example of a degradation state determination device 100 of the first embodiment. The degradation state determination device (hereinafter referred to as determination device) 100 of the first embodiment determines the degradation state of a lithium metal battery 10. The lithium metal battery 10 has a negative electrode containing lithium. The lithium metal battery 10 is a secondary battery that can be charged and discharged. The lithium metal battery 10 is used, for example, by being mounted on a vehicle.

[0019] For example, the determination device 100 removes the lithium metal battery 10 that was installed in the vehicle, determines its degradation state, and determines whether the degree of degradation of the lithium metal battery 10 is sufficient to allow reuse. When the determination device 100 determines the degradation state of the lithium metal battery 10, an AC power source 20 and an ammeter 30 are connected to the lithium metal battery 10. The degradation state of the lithium metal battery 10 determined by the determination device 100 is primarily a state related to structural destruction of the lithium metal battery 10 due to the growth of an SEI layer attached to the negative electrode.

[0020] Prior to describing the determination device 100, the lithium metal battery 10 will be described. Fig. 2 is a diagram showing an example of a state in which the lithium metal battery 10 is mounted on a vehicle M. In addition to the lithium metal battery 10, the vehicle M is also equipped with an electrical device 40, a preliminary degradation measuring device 50, and a converter 60. In the vehicle M, the preliminary degradation measuring device 50 preliminarily measures the degradation of the lithium metal battery 10 when the vehicle M supplies power to the electrical device 40 using the lithium metal battery 10.

[0021] The lithium metal battery 10 is, for example, a semi-solid battery. The lithium metal battery 10 includes, for example, a positive electrode 11, a negative electrode 12, and an electrolyte 13. The positive electrode 11 includes, for example, a positive electrode current collector 11A and a positive electrode active material layer 11B. The positive electrode current collector 11A is made of, for example, a current collecting foil such as aluminum. The positive electrode active material layer 11B is made of, for example, a layer of lithium cobalt oxide.

[0022] The negative electrode 12 includes, for example, a negative electrode current collector 12A and a negative electrode active material layer 12B. The negative electrode current collector 12A is made of, for example, a current collecting foil such as copper. The negative electrode active material layer 12B is made of, for example, a metallic lithium layer. The electrolyte 13 is a semi-solid electrolyte containing lithium ions (Li+). The electrolyte 13 is partitioned into a positive electrode 11 side and a negative electrode 12 side by a separator 13S.

[0023] During discharge, when the lithium metal battery 10 supplies power to an electrical device 40 mounted on the vehicle M, lithium ions Li+ flow from the negative electrode active material layer 12B through the separator 13S to the positive electrode 11. Along with the flow of lithium ions Li+, electrons e flow from the negative electrode 12 through the circuit of the electrical device 40 to the positive electrode 11. Due to the flow of lithium ions Li+ and electrons e, a current flows from the positive electrode 11 to the negative electrode 12, discharging the lithium metal battery 10. In the negative electrode active material layer 12B, metallic lithium dissolves as the lithium metal battery 10 discharges.

[0024] The lithium metal battery 10 is charged by a charging facility 80 located outside the vehicle M. The charging facility 80 is installed, for example, at the home of the owner of the vehicle M or at a charging station. During charging, lithium ions Li+ flow from the positive electrode active material layer 11B through the separator 13S to the negative electrode 12 side.

[0025] Along with the flow of lithium ions Li+, electrons e flow from positive electrode 11 to 12 through charging equipment 80. The flow of lithium ions Li+ and electrons e causes a current to flow from negative electrode 12 to positive electrode 11, charging lithium metal battery 10. In negative electrode active material layer 12B, metallic lithium is deposited as lithium metal battery 10 is charged.

[0026] 3 is a diagram schematically illustrating changes in the negative electrode 12 when the lithium metal battery 10 is repeatedly charged and discharged. Repeated charge and discharge of the lithium metal battery 10 causes metallic lithium to precipitate in the negative electrode active material layer 12B. As a result, the SEI layer Q gradually thickens over time as the lithium metal battery 10 deteriorates, and the thickness of the negative electrode 12 gradually increases from a first thickness D1 to a second thickness D2, a third thickness D3, and a fourth thickness D4.

[0027] The electrical equipment 40 includes various devices that are mounted on the vehicle M and are supplied with power by the lithium metal battery 10. The electrical equipment 40 includes, for example, a traction motor for driving the vehicle M, an air conditioning control device for controlling the air conditioning in the passenger compartment of the vehicle M, and a monitor for displaying images to provide various information to the occupants.

[0028] The preliminary deterioration measuring device 50 includes, for example, a voltage detector 51, a current detector 52, a calculation device 53, and a providing device. The voltage detector 51 detects the voltage value of the terminal voltage of the lithium metal battery 10. The current detector 52 detects the current value of the current flowing from the positive electrode 11 side to the negative electrode 12 side of the lithium metal battery 10.

[0029] The calculation device 53 estimates the growth degree of the SEI film in the lithium metal layer of the lithium metal battery 10 based on the voltage value detected by the voltage detector 51 and the current value detected by the current detector 52. In estimating the growth degree of the SEI film, the calculation device 53 measures the current discharged from the lithium metal battery 10 mounted on the vehicle M after a predetermined time of 0.001 to 1.0 seconds, for example, 0.1 seconds, has elapsed.

[0030] The arithmetic unit 53 measures the voltage drop after 0.1 seconds based on the voltage value output by the voltage detector 51, for example. The arithmetic unit 53 further measures the current after 0.1 seconds based on the current value output by the current detector 52. The arithmetic unit 53 calculates the impedance after 0.1 seconds (hereinafter referred to as the 0.1-second resistance) based on the measured voltage drop after 0.1 seconds and current after 0.1 seconds. Specifically, the arithmetic unit 53 calculates the 0.1-second resistance by dividing the voltage drop after 0.1 seconds by the current after 0.1 seconds. The 0.1-second resistance increases as the number of charge / discharge cycles of the lithium metal battery 10 increases.

[0031] The providing device 54 stores the 0.1-second resistance calculated by the arithmetic device 53. When the lithium metal battery 10 is removed from the vehicle M and connected to the determination device 100, the providing device 54 provides the determination device 100 with some or all of the stored 0.1-second resistances, for example, the latest value of the 0.1-second resistances.

[0032] Returning to FIG. 1 , AC power supply 20 applies a test voltage to lithium metal battery 10 under the control of determination device 100. The test voltage is applied to lithium metal battery 10 as, for example, an AC current. Ammeter 30 is connected to lithium metal battery 10. Ammeter 30 measures, for example, the current value of the current discharged from lithium metal battery 10 to which test voltage has been applied by AC power supply 20. Ammeter 30 transmits a current signal based on the measured current value to determination device 100.

[0033] The determination device 100 includes, for example, a communication unit 110, a storage unit 120, and a processing unit 130. The communication unit 110 transmits and receives signals between the determination device 100 and an external device. The communication unit 110 transmits, for example, a current supply signal generated by the processing unit 130 to the AC power supply 20. The communication unit 110 receives a current signal transmitted by the ammeter 30. The transmission and reception performed by the communication unit 110 may be wired communication via wiring or wireless communication via a network.

[0034] The storage unit 120 is formed of, for example, a hard disk drive (HDD) or a flash memory. The storage unit 120 stores a deterioration determination map 121 and a preliminary determination map 122. The deterioration determination map 121 is a map that indicates the relationship between the thickness of the negative electrode 12 and the resistance value of the lithium metal battery 10, and is a map that has been created in advance.

[0035] 4 is a diagram showing an example of a visualized deterioration determination map 121. The deterioration determination map 121 is a map obtained, for example, by measuring the resistance or AC impedance for 0.1 seconds when an AC voltage is applied to a lithium metal battery 10 produced for testing and having a known thickness of the negative electrode 12, and then determining the bulk resistance and the negative electrode reaction resistance, and thereby determining the resistance value relative to the thickness of the negative electrode 12.

[0036] The deterioration determination map 121 may be created using a lithium metal battery with an unknown thickness of the negative electrode 12. In this case, the deterioration determination map 121 may be generated by measuring the thickness of the negative electrode 12 when an AC voltage is applied to the lithium metal battery 10, and by using the resistance value calculated when the AC voltage is applied to the lithium metal battery 10. The deterioration determination map 121 is an example of a first map.

[0037] The deterioration determination map 121 sets a first reference value B1 that serves as a criterion for determining whether the deterioration of the lithium metal battery 10 has progressed and the lithium metal battery 10 is unreusable. The first reference value B1 is, for example, a resistance value corresponding to the thickness of the negative electrode 12 at which it is determined that the growth of the SEI layer formed on the negative electrode 12 has progressed and that the lithium metal battery 10 is likely to suffer structural damage.

[0038] The preliminary determination map 122 is, for example, a map showing the relationship between the thickness of the negative electrode 12 and the resistance value of the 0.1-second resistance, and is a map created in advance. FIG. 5 is a diagram showing an example of a visualized preliminary determination map 122. The preliminary determination map 122 is calculated, for example, using a resistance value calculated based on the current value of the current discharged from a lithium metal battery 10 having a known thickness of the negative electrode 12. The preliminary determination map 122 may be generated by measuring the thickness of the negative electrode 12 when the current is discharged from the lithium metal battery 10 and using a resistance value calculated based on the current value of the current discharged from the lithium metal battery 10.

[0039] The preliminary determination map 122 has a preliminary reference value B0 set therein, which serves as a reference for preliminary determining whether the lithium metal battery 10 has deteriorated to the point where it is no longer reusable. The preliminary reference value B0 is, for example, a resistance value corresponding to the thickness of the negative electrode 12 at which it is determined that the growth of the SEI layer formed on the negative electrode 12 has progressed and that the lithium metal battery 10 may suffer structural damage. The preliminary reference value B0 is a value greater than the first reference value B1.

[0040] The processing unit 130 includes, for example, a control unit 131, an acquisition unit 132, and a determination unit 133. These components are realized by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware.

[0041] The program may be stored in advance in a storage unit 120 (a storage device with a non-transitory storage medium) such as an HDD or flash memory, or may be stored in a removable storage medium (a non-transitory storage medium) such as a DVD or CD-ROM, and installed by inserting the storage medium into a drive device.

[0042] For example, when the determination device 100 determines the degradation state of the lithium metal battery 10, the control unit 131 performs overall control of the operation of the determination device 100. For example, when starting to determine the degradation state of the lithium metal battery 10, the control unit 131 generates a current supply signal for applying a predetermined AC voltage as a test voltage to the lithium metal battery 10 and transmits it to the AC power source 20.

[0043] The acquisition unit 132 acquires resistance value information relating to the resistance value obtained by applying a voltage to the lithium metal battery 10. The acquisition unit 132 acquires, for example, a current signal transmitted by the ammeter 30 and received by the communication unit 110. Based on the acquired current signal, the acquisition unit 132 acquires the current value of the current discharged by the lithium metal battery 10 to which the test voltage has been applied.

[0044] The acquisition unit 132 calculates the resistance value of the lithium metal battery 10 based on the acquired current value and the voltage value of the voltage applied to the lithium metal battery 10 by the AC power supply 20. The acquisition unit 132 calculates the resistance value of the lithium metal battery 10, for example, by dividing the acquired current value by the voltage value of the voltage applied to the lithium metal battery 10. The acquisition unit 132 acquires the calculated resistance value as resistance value information. The acquisition unit 132 also acquires information on the 0.1-second resistance of the lithium metal battery 10, which is provided by the providing device 54, as a preliminary assessment result of the lithium metal battery 10.

[0045] The determination unit 133 determines the degradation state of the lithium metal battery 10 based on the degradation determination map 121 and the resistance value information acquired by the acquisition unit 132. The determination unit 133 calculates the thickness of the negative electrode 12 of the lithium metal battery 10, for example, by referring to the degradation determination map 121 for a resistance value based on the acquired resistance value information. The determination unit 133 determines the degradation state of the lithium metal battery 10 by comparing the calculated thickness of the negative electrode 12 with a first reference value B1.

[0046] Before determining the state of degradation of the lithium metal battery 10 by comparing the thickness of the negative electrode 12 with the first reference value B1, the determination unit 133 preliminarily determines the state of degradation of the lithium metal battery 10 based on the 0.1-second resistance provided by the lithium metal battery 10 providing device 54 and acquired by the acquisition unit 132, and the preliminary determination map 122. For example, the determination unit 133 references the 0.1-second resistance to the preliminary determination map 122, and compares the 0.1-second resistance with the preliminary reference value B0 to perform a preliminarily determination of the state of degradation of the lithium metal battery 10.

[0047] Next, the processing in the determination device 100 of the first embodiment will be described. Fig. 6 is a flowchart showing an example of the processing in the determination device 100 of the first embodiment. The flowchart shown in Fig. 6 is executed after the lithium metal battery 10, which has been removed from the vehicle M, is connected to the determination device 100.

[0048] The determination device 100 first acquires the latest 0.1-second resistance of the lithium metal battery 10 provided by the providing device 54 in the acquisition unit 132 (step S101). Next, the determination unit 133 refers to the 0.1-second resistance acquired by the acquisition unit 132 in the preliminary determination map 122 (step S103), and determines whether the acquired 0.1-second resistance exceeds the preliminary reference value B0 (step S105).

[0049] If the determination unit 133 determines that the acquired 0.1-second resistance exceeds the preliminary reference value B0, the determination device 100 performs impedance measurement (step S107) to acquire the resistance value of the lithium metal battery 10. In the impedance measurement, the control unit 131 first transmits a current supply signal to the AC power supply 20. After the AC power supply 20 receives the current supply signal and applies a test voltage to the lithium metal battery 10, the ammeter 30 measures the current value of the current discharged from the lithium metal battery 10, and generates and transmits a current signal based on the current value to the determination device 100.

[0050] The determination device 100 acquires the current signal transmitted by the ammeter 30 in the acquisition unit 132. Next, the acquisition unit 132 calculates the resistance value of the lithium metal battery 10 based on the current value based on the acquired current signal and the voltage value of the voltage applied to the lithium metal battery 10 by the AC power supply 20, and acquires resistance value information. Impedance measurement is performed in this manner.

[0051] Next, the determination unit 133 refers to the degradation determination map 121 for the resistance value based on the resistance value information acquired by the acquisition unit 132 (step S109), and determines whether the resistance value of the lithium metal battery 10 exceeds a first reference value B1 (step S111). If it is determined that the resistance value of the lithium metal battery 10 exceeds the first reference value B1, the determination unit 133 determines that the lithium metal battery 10 cannot be reused (step S113). In this way, the determination device 100 ends the process shown in FIG.

[0052] If the determination unit 133 determines in step S105 that the acquired 0.1-second resistance does not exceed the preliminary reference value B0 (is equal to or less than the preliminary reference value B0), the determination unit 133 determines that reuse is possible (step S115), and the determination device 100 ends the processing shown in Fig. 6. Also, if the determination unit 133 determines in step S111 that the resistance value of the lithium metal battery 10 does not exceed the first reference value B1 (is equal to or less than the first reference value B1), the determination unit 133 also determines that reuse is possible (step S115), and the determination device 100 ends the processing shown in Fig. 6.

[0053] The determination device 100 of the first embodiment determines the deterioration of the lithium metal battery 10 using the deterioration determination map 121. This allows for accurate determination of the deterioration of the lithium metal battery 10. Furthermore, when the lithium metal battery 10 is removed from the vehicle, the determination device 100 of the first embodiment determines the deterioration of the lithium metal battery 10 that is preliminarily determined to be deteriorated based on the 0.1-second resistance, and determines whether the lithium metal battery 10 can be reused. This allows for the omission of the deterioration determination for lithium metal batteries 10 that are unlikely to be reused, thereby allowing for efficient determination of whether the lithium metal battery 10 can be reused.

[0054] <Second embodiment> Next, a second embodiment will be described. Fig. 7 is a block diagram showing an example of a determination device 200 of the second embodiment. The second embodiment differs from the first embodiment mainly in that a bipolar deterioration determination map 123 is stored in the storage unit 120 and in the processing that utilizes the bipolar deterioration determination map 123. In the following description, elements common to the first embodiment will be assigned the same reference numerals and their description may be omitted.

[0055] In the determination device 100 of the second embodiment, the storage unit 120 stores a bipolar deterioration determination map 123 instead of the deterioration determination map 121. The bipolar deterioration determination map 123 is a map that is created in advance and indicates the relationship between the deterioration levels of the positive electrode 11 and negative electrode and the resistance value of the lithium metal battery 10. FIG. 8 is a diagram showing an example of a visualized bipolar deterioration determination map 123.

[0056] The bipolar deterioration determination map 123 is generated, for example, using resistance values ​​calculated when an AC voltage is applied to a lithium metal battery 10 whose degrees of deterioration of the positive electrode 11 and negative electrode are known. The degree of deterioration of the positive electrode 11 appears, for example, in changes between layers of the positive electrode 11; as deterioration of the positive electrode 11 progresses, the thickness of the positive electrode 11 increases, resulting in an increase in the resistance value of the lithium metal battery 10. The degree of deterioration of the negative electrode 12 is determined, for example, by using the thickness of the negative electrode 12 in the first embodiment.

[0057] The bipolar electrode deterioration determination map 123 includes a positive electrode deterioration determination map 124 and a negative electrode deterioration determination map 125. The positive electrode deterioration determination map 124 is a map obtained, for example, by measuring the 0.1-second resistance or AC impedance of the lithium metal battery 10, determining the bulk resistance and the positive electrode reaction resistance, and determining the resistance value relative to the thickness of the positive electrode 11. The negative electrode deterioration determination map 125 is a map similar to the deterioration determination map 121 in the first embodiment. The positive electrode deterioration determination map 124 is an example of a second map.

[0058] The positive electrode deterioration determination map 124 and the negative electrode deterioration determination map 125 are set with a second reference value B2 and a third reference value B3, respectively, which are used to determine whether the lithium metal battery 10 has deteriorated to the point where it is deemed unreusable. The second reference value B2 is, for example, a resistance value corresponding to the thickness of the positive electrode 11 at which it is determined that the deterioration of the positive electrode 11 has progressed to the point where it is highly likely that the lithium metal battery 10 cannot be reused. The third reference value B3 is, for example, a value corresponding to the first reference value B1 in the first embodiment.

[0059] Next, the processing in the determination device 200 of the second embodiment will be described. Fig. 9 is a flowchart showing an example of the processing in the determination device 200 of the second embodiment. The flowchart shown in Fig. 9 is executed after it is determined that the preliminary reference value is exceeded up to step S105 shown in Fig. 6 of the first embodiment, for example.

[0060] The determination device 200 first performs impedance measurement (step S201) to obtain the resistance value of the lithium metal battery 10. In the impedance measurement, the ammeter 30 measures the current value of the current discharged from the lithium metal battery 10 using the same procedure as in the first embodiment, and generates and transmits a current signal based on the current value to the determination device 100. The determination device 100 calculates the resistance value of the lithium metal battery 10 using the same procedure as in the first embodiment, and obtains resistance value information.

[0061] Next, the determination unit 133 refers to the bipolar degradation determination map 123 for the resistance value based on the resistance value information acquired by the acquisition unit 132 (step S203), and determines whether the resistance value of the lithium metal battery 10 exceeds the second reference value B2 or the third reference value B3 (step S205). If the determination unit 133 determines that the resistance value of the lithium metal battery 10 exceeds the second reference value B2 or the third reference value B3, the determination unit 133 determines that the lithium metal battery 10 is not reusable (step S207). In this manner, the determination device 200 ends the processing shown in FIG. 9. If the determination unit 133 determines that the resistance value of the lithium metal battery 10 does not exceed either the second reference value B2 or the third reference value B3 (is equal to or less than the second reference value B2 and the third reference value B3), the determination unit 133 determines that the lithium metal battery 10 is reusable (step S209). In this manner, the determination device 100 ends the processing shown in FIG. 9.

[0062] Here, we will explain the procedure for determining the bulk resistance, negative electrode reaction resistance, and positive electrode reaction resistance used when generating the bipolar deterioration determination map 123. Fig. 10 is a graph showing an example of the relationship between the impedance mainly derived from the resistance value and the impedance mainly derived from the capacitor component. In Fig. 10, the horizontal axis shows the impedance mainly derived from the resistance value, and the vertical axis shows the impedance mainly derived from the capacitor.

[0063] 10 shows the relationship between the impedance derived from the measured resistance value (hereinafter referred to as resistance impedance) and the impedance derived mainly from the capacitor component (hereinafter referred to as capacitor impedance) for three lithium metal batteries 10. The measurement results for each of the three lithium metal batteries 10 are shown as measurement result 1, measurement result 2, and measurement result 3.

[0064] In the first capacitor curve K1, the second capacitor curve K2, and the third capacitor curve K3, which respectively show the first measurement result, the second measurement result, and the third measurement result, the capacitor impedance is 0 before an AC voltage is applied to the lithium metal battery 10. When an AC voltage is applied to the lithium metal battery 10 from this state, both the resistance impedance and the capacitor impedance increase.

[0065] In the initial stage of applying an AC voltage to the lithium metal battery 10, as the resistance impedance increases, the capacitor impedance also increases. However, once the resistance impedance reaches a first peak, the relationship shifts to one in which the capacitor impedance decreases as the resistance impedance increases. Furthermore, once the resistance impedance reaches a first nadir, the relationship shifts back to one in which the capacitor impedance increases as the resistance impedance increases. Therefore, the first upwardly convex first arc lines K11, K21, and K31 are generated on the first capacitor curve K1, the second capacitor curve K2, and the third capacitor curve K3.

[0066] Next, when the resistance impedance reaches a second peak, the relationship becomes such that the capacitor impedance decreases as the resistance impedance increases. Furthermore, when the resistance impedance reaches a second bottom, the relationship becomes such that the capacitor impedance increases as the resistance impedance increases. Therefore, the first capacitor curve K1, the second capacitor curve K2, and the third capacitor curve K3 each have a convex second arc line K12, K22, or K32. If the lithium metal battery 10 does not contain a capacitor component, the first capacitor curve K1, the second capacitor curve K2, and the third capacitor curve K3 would all be linear.

[0067] Since the lithium metal battery 10 has a capacitor component, first arcuate lines K11, K21, K31 and second arcuate lines K12, K22, K32 are generated on the first capacitor curve K1, the second capacitor curve K2, and the third capacitor curve K3, respectively. The left end points of the first arcuate lines K11, K21, K31 on the first capacitor curve K1, the second capacitor curve K2, and the third capacitor curve K3 are considered to be the bulk resistance R0.

[0068] The length (resistance impedance) of the first arcuate wires K11, K21, and K31 is considered to be the negative electrode reaction resistance R1 that occurs mainly due to the influence of the negative electrode 12. The length of the second arcuate wires K12, K22, and K32 is considered to be the positive electrode reaction resistance R2 that occurs mainly due to the influence of the positive electrode 11. Theoretically, the 0.1 second resistance is obtained by adding the bulk resistance R0, the negative electrode reaction resistance R1, and the positive electrode reaction resistance R2.

[0069] The determination device 200 of the second embodiment has the same effects as those of the first embodiment. The determination device 200 of the second embodiment further determines the deterioration of the lithium metal battery 10 using a bipolar deterioration determination map 123 including a positive electrode deterioration determination map 124 and a negative electrode deterioration determination map 125. This allows the deterioration of the lithium metal battery 10 to be determined more accurately.

[0070] In each of the above embodiments, the degradation state of the lithium metal battery 10 is determined after removal from the vehicle M, but the determination device 100, 200 may be connected to the lithium metal battery 10 mounted on the vehicle M to determine the degradation state of the lithium metal battery 10. In this case, an AC voltage is applied to the lithium metal battery 10 mounted on the vehicle M.

[0071] When applying a voltage to the lithium metal battery 10 to determine the degradation state of the lithium metal battery 10, an AC power source 20 may be used, or a voltage supplied by a charging facility 80 shown in Fig. 2 may be used. When using a voltage supplied by the charging facility 80, the converter 60 may supply an AC voltage to the lithium metal battery 10 by reducing the AC voltage supplied to the charging facility 80 while keeping it as an AC voltage.

[0072] Furthermore, for lithium metal batteries 10 determined to be reusable, the remaining life of the lithium metal battery 10 when reused may be estimated based on the measured thickness of the negative electrode 12. In this case, the remaining life of the lithium metal battery 10 may be shortened as the thickness of the negative electrode 12 increases. When a lithium metal battery 10 determined to be reusable is used in combination, lithium metal batteries 10 with similar remaining lives may be combined.

[0073] The above-described embodiment can be expressed as follows. a storage medium for storing computer-readable instructions; a processor connected to the storage medium; The processor executes the computer-readable instructions to: Obtaining resistance value information relating to a resistance value obtained by applying a voltage to a lithium metal battery including a negative electrode containing lithium; determining a deterioration state of the lithium metal battery based on a first map created in advance that indicates a relationship between the thickness of the negative electrode and the resistance value and the acquired resistance value information; A device for determining the deterioration state of lithium metal batteries.

[0074] The above describes the form for carrying out the present invention using an embodiment, but the present invention is not limited to such an embodiment, and various modifications and substitutions can be made within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0075] 10. Lithium metal batteries 11 Positive electrode 11A positive electrode current collector 11B Positive electrode active material layer 12 Negative electrode 12A negative electrode current collector 12B Negative electrode active material layer 13 Electrolytes 13S Separator 20 AC power supply 30 ammeter 40 Electrical Equipment 50 Preliminary deterioration measurement device 51 Voltage detector 52 Current detector 53 Arithmetic unit 54 Providing device 60 converter 80 Charging equipment 100,200 Determination device (deterioration state determination device) 110 Communications Department 120 Storage section 121 Deterioration Determination Map 122 Preliminary Judgment Map 123 Polarity Deterioration Determination Map 124 Positive electrode deterioration determination map 125 Negative electrode deterioration determination map 130 Processing section 131 Control Unit 132 Acquisition Department 133 Judgment section M vehicle Q SEI layer R0 bulk resistance R1 negative electrode reaction resistance R2 Positive electrode reaction resistance

Claims

1. an acquisition unit that acquires resistance value information relating to a resistance value obtained by applying a voltage to a lithium metal battery having a negative electrode containing lithium; a determination unit that determines a degradation state of the lithium metal battery based on a first map that is created in advance and that indicates a relationship between the thickness of the negative electrode and the resistance value, and the acquired resistance value information; A device for determining the deterioration state of lithium metal batteries.

2. the acquiring unit acquires the resistance value information based on a current value of a current discharged from the lithium metal battery. The device for determining the deterioration state of a lithium metal battery according to claim 1.

3. the determination unit determines that the deterioration state of the lithium metal battery is in a state where it can be reused when the acquired resistance value is a resistance value at which the thickness of the negative electrode is equal to or less than a first reference value; The device for determining the deterioration state of a lithium metal battery according to claim 1.

4. the determination unit determines the deterioration state of the lithium metal battery further based on a second map created in advance and showing a relationship between the thickness of the positive electrode of the lithium metal battery and the resistance value; When the acquired resistance value is a resistance value at which the thickness of the positive electrode is equal to or less than a second reference value, the deterioration state of the lithium metal battery is determined to be in a state where it can be reused. The device for determining the deterioration state of a lithium metal battery according to claim 3.

5. the lithium metal battery is a lithium metal battery mounted on a vehicle, the acquisition unit acquires a resistance value obtained by applying an AC voltage to the lithium metal battery removed from the vehicle. The device for determining the deterioration state of a lithium metal battery according to claim 3 or 4.

6. the lithium metal battery is a lithium metal battery mounted on a vehicle, the acquisition unit acquires a resistance value obtained by applying an AC voltage to the lithium metal battery mounted on the vehicle. The device for determining the deterioration state of a lithium metal battery according to claim 1.

7. the lithium metal battery is a lithium metal battery mounted on a vehicle, the acquisition unit acquires a measurement result of a current discharged from the lithium metal battery mounted on the vehicle at a timing after a predetermined time of 0.001 seconds or more and 1.0 seconds or less has elapsed, and acquires a preliminary determination result of a deterioration state of the lithium metal battery based on the measurement result; The determination unit preliminarily determines the state of deterioration of the lithium metal battery based on a preliminary determination result obtained by preliminarily determining the state of deterioration of the lithium metal battery based on the acquired measurement result. The device for determining the deterioration state of a lithium metal battery according to claim 1.

8. The computer Obtaining resistance value information relating to a resistance value obtained by applying a voltage to a lithium metal battery having a negative electrode containing lithium; determining a degradation state of the lithium metal battery based on a first map that is created in advance and that indicates a relationship between the thickness of the negative electrode and the resistance value, and the acquired resistance value information; A method for determining the deterioration state of a lithium metal battery.

9. On the computer, Obtaining resistance value information relating to a resistance value obtained by applying a voltage to a lithium metal battery having a negative electrode containing lithium; determining a deterioration state of the lithium metal battery based on a first map that is created in advance and that indicates a relationship between the thickness of the negative electrode and the resistance value, and the acquired resistance value information; program.

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