Ion movement measuring device and movement measuring method

Abstract

The present invention is to solve the problem that the movement state of the second atomic ion at the time of application of the target voltage and the movement state of the second atomic ion due to diffusion can be detected with high accuracy. To solve the above problem, the ion movement measuring device has a test body and a detection device. The test body has a first electrode and a second electrode, and an electrolyte disposed between the first electrode and the second electrode. The first electrode and the second electrode have layers of the same element as each other, and are at the same potential as each other in a state where no voltage is applied to the test body from the outside. At least the aforementioned first electrode contains a first atom and a second atom of the element with the highest natural abundance ratio in the element at a higher abundance ratio than the natural abundance ratio of the isotopes. The detection device detects ions of the first atom and the second atom released from the electrolyte.

Description

TECHNICAL FIELD

[0001] The present application relates to a measuring device and a measuring method of ions moving in an electrolyte. BACKGROUND

[0002] In recent years, from the viewpoint of reducing the discharge of carbon dioxide to reduce the adverse effects on the global environment, etc., electric vehicles such as electric vehicles (EV) or hybrid electric vehicles (HEV) are becoming popular. Therefore, it is urgently needed to develop high-performance batteries.

[0003] [Prior Art Documents]

[0004] (Patent Document)

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-144859 SUMMARY

[0006] [Problems to be Solved by the Invention]

[0007] In the development of batteries, it is important to correctly measure ion conductivity that affects output characteristics, etc. However, in a test body of a lithium ion battery having an electrolyte between a positive electrode and a negative electrode, for example, it is difficult to distinguish and observe specific lithium atom ions moving in the electrolyte from other lithium atom ions. Therefore, the present inventors and others considered that a portion of the positive electrode that abuts against the electrolyte is formed mainly of lithium 6 atoms, which are isotopes of lithium 7 atoms having the highest natural abundance ratio among lithium atoms, and that a current flows from the positive electrode to the negative electrode through the electrolyte, whereby lithium 6 atom ions moving in the electrolyte are observed.

[0008] According to this method, lithium 6 atom ions can be distinguished from lithium 7 atom ions and observed according to the difference in mass, but the present inventors and others focused on the following problem. That is, in the case where a base portion of the positive electrode is formed of a positive electrode material as it is for a battery, and a base portion of the negative electrode is formed of a negative electrode material as it is for a battery, etc., an unexpected voltage is applied between the terminals of the electrolyte due to the potential difference caused by the difference between these materials. Thus, it is not possible to detect the movement state of lithium 6 atom ions at the time when a target voltage is applied. In addition, in a diffusion test of lithium 6 atom ions in which the test body is left without applying a voltage, it is not possible to accurately detect the movement state of lithium 6 atom ions caused only by diffusion due to this unexpected voltage.

[0009] In addition, the above shows the case where lithium 6 atom ions are distinguished from lithium 7 atom ions and observed, but second atom ions can be distinguished from first atom ions and observed in other elements. However, the same problem occurs in this case as well.

[0010] The present application was achieved in view of the above-described circumstances, and aims at enabling high-precision detection of a movement state of a second atomic ion such as a lithium-6 atomic ion at a target voltage application time, and a movement state of the second atomic ion due to diffusion.

[0011] [Technical means for solving the problem]

[0012] The present inventors found that if an electrolyte is sandwiched by a first electrode containing a second atomic ion at a higher abundance ratio than a natural abundance ratio and a second electrode at the same potential as the first electrode, and a voltage is applied between the two electrodes from the outside, a movement state of the second atomic ion at a target voltage application time can be detected with high precision, thereby completing the present application. The present application is a movement measuring device of ions of (1) to (4) below and a movement measuring method of ions of (5) to (10) below.

[0013] (1) A movement measuring device of ions, comprising:

[0014] a test body having a first electrode and a second electrode, and an electrolyte disposed between the first electrode and the second electrode,

[0015] the first electrode and the second electrode have layers of the same element as each other, and are at the same potential as each other in a state where no voltage is applied to the test body from the outside,

[0016] and at least the first electrode contains a first atomic ion and a second atomic ion of an isotope, which are the highest in natural abundance ratio among the elements, at a higher abundance ratio than a natural abundance ratio of the second atomic ion; and

[0017] a detection device that detects ions of the first atomic ion and the second atomic ion released from the electrolyte.

[0018] In addition, regarding the first electrode and the second electrode being at the same potential as each other in a state where no voltage is applied to the test body from the outside, for example, the first electrode and the second electrode can be made by being formed only by layers of the same element, or the first electrode and the second electrode can be made by laminating the layers of the same element on base members of the same material as each other.

[0019] According to the present configuration, the ions of the second atom can be distinguished from the ions of the first atom based on the mass difference and observed. Further, by applying a voltage between the first electrode and the second electrode from the outside of the test body, a voltage of a target time can be applied between the terminals of the electrolyte. Further, since the first electrode and the second electrode are the same element, they are at the same potential in a state where no voltage is applied to the test body from the outside, and thus there is no concern that an unintended voltage is applied between the terminals of the electrolyte. Therefore, in a case where a voltage is applied to the test body from the outside, the movement state of the ions of the second atom at the time when the target voltage is applied can be detected with high precision. In addition, in a case where the test body is left without applying a voltage to the test body from the outside, the movement state due to diffusion of the ions of the second atom can be detected with high precision without being affected by an unintended voltage.

[0020] (2) The ion movement measuring apparatus according to the aforementioned (1), wherein the ion movement measuring apparatus has a movement device that causes the ions of the first atom and the second atom to move from the first electrode side to the second electrode side in the test body by applying a voltage between the first electrode and the second electrode to form a high potential on the first electrode side.

[0021] According to the present configuration, the desired voltage can be applied between the first electrode and the second electrode by the movement device.

[0022] (3) The ion movement measuring apparatus according to the aforementioned (1) or (2),

[0023] the electrolyte is a solid electrolyte,

[0024] the same element is lithium, the first atom is lithium-7, and the second atom is lithium-6.

[0025] According to the present configuration, the present application can be used in development tests of lithium ion batteries having a solid electrolyte.

[0026] (4) The ion movement measuring apparatus according to the aforementioned (1) or (2), wherein the second electrode contains the second atom at a higher abundance ratio than the natural abundance ratio of the second atom.

[0027] According to the present configuration, the first electrode and the second electrode can be manufactured using the same material. Therefore, the manufacturing of the test body is facilitated.

[0028] (5) The ion movement measuring apparatus according to the aforementioned (1) or (2), wherein the second electrode contains the first atom at a higher abundance ratio than the abundance ratio of the first atom in the first electrode, and contains the second atom at a lower abundance ratio than the abundance ratio of the second atom in the first electrode.

[0029] According to the present configuration, since the first electrode contains the second atom at a higher abundance ratio than the second electrode, it is easy to determine that the increase in the second atom ions in the electrolyte is because the second atom ions move from the first electrode side.

[0030] (6) The ion movement measuring apparatus according to the above (1) or (2), wherein the detection means detects ions of the first atom and the second atom at a plurality of points in the test body in a direction from the first electrode side toward the second electrode side,

[0031] The ion movement measuring apparatus further has:

[0032] a creator that creates a measured curve that depicts a concentration of ions of the first atom or the second atom at the plurality of points, based on a result of the detection by the detection means;

[0033] a calculator that calculates, for each of a plurality of diffusion parameters that include a diffusion coefficient of the ions in the test body, a calculation curve that is calculated with respect to the concentration; and

[0034] an estimator that estimates the diffusion parameter corresponding to the calculated calculation curve that is determined to have the smallest deviation from the measured curve.

[0035] In the present configuration, as in the case of the above (1) cited above, the first electrode and the second electrode are also at the same potential, and thus there is no concern about applying an unexpected voltage between the terminals of the electrolyte. In this case, the detection means detects ions at a plurality of points in the test body. Also, the creator creates a measured curve based on a result of the detection by the detection means. Thus, it is possible to detect movement due to diffusion of ions with high precision and to create a measured curve with high precision, without being affected by an unexpected voltage.

[0036] Also, the estimator estimates a calculation curve that is determined to have the smallest deviation from the measured curve, and estimates the diffusion parameter corresponding to the calculation curve. Thus, it is possible to inversely calculate a calculation curve when a condition such as a placement time or a temperature is changed, based on the estimated diffusion parameter. Thus, it is possible to estimate a diffusion state of ions when the condition is changed.

[0037] (7) The ion movement measuring apparatus according to the above (6), wherein the diffusion parameters include a diffusion coefficient of the ions that diffuse from the electrolyte to one of the first electrode and the second electrode and a diffusion coefficient of the ions that diffuse from the electrode to the electrolyte.

[0038] According to the present configuration, by including the diffusion coefficient of ions at a plurality of portions in the test body in the diffusion parameter, the diffusion state of ions in the test body can be estimated with higher accuracy.

[0039] (8) The ion movement measuring device according to (1) or (2) above, wherein the electrolyte of the test body has at least one of an active material, a conductive aid, and a binder.

[0040] The positive electrode material in the secondary electrode sometimes contains an active material, a conductive aid, a binder, and the like. Therefore, according to the present configuration, as the electrolyte of the test body, the positive electrode material in the secondary electrode or the like can be used.

[0041] (9) An ion movement measuring method using a test body,

[0042] the test body having a first electrode and a second electrode, and an electrolyte disposed between the first electrode and the second electrode,

[0043] the first electrode and the second electrode have a layer of the same element as each other, and are at the same potential as each other in a state where no voltage is applied to the test body from the outside,

[0044] and at least the first electrode contains a first atom and a second atom of the element having the highest natural abundance ratio, at a higher abundance ratio than the natural abundance ratio of the second atom of the isotope;

[0045] the ion movement measuring method has:

[0046] a detection step of detecting ions of the first atom and the second atom released from the electrolyte.

[0047] According to the present method, the same effects as the device of (1) above can be obtained.

[0048] (10) The ion movement measuring method according to (9) above, wherein the ion movement measuring method has:

[0049] a movement step of causing ions of the first atom and the second atom to move from the first electrode side to the second electrode side in the test body, by applying a voltage between the first electrode and the second electrode from the outside of the test body to make the first electrode side a high potential,

[0050] the detection step is performed after or during the movement step.

[0051] According to the present configuration, the same effects as the device of (2) above can be obtained.

[0052] (11) The ion movement measuring method according to (9) or (10) above, wherein

[0053] The aforementioned electrolyte has a solid electrolyte,

[0054] The aforementioned same element is lithium, the aforementioned first atom is a lithium 7 atom, and the aforementioned second atom is a lithium 6 atom.

[0055] According to the present configuration, the present method can be employed in development tests of lithium ion batteries having a solid electrolyte.

[0056] (12) The ion movement measuring method according to (10) above, wherein the detection process is performed in a state in which no voltage is applied to the test body from the outside after the movement process.

[0057] According to the present configuration, the movement state of ions can be detected simply at the time of application of a target voltage, as compared with the case in which ions released from the electrolyte are detected at the same time as the application of a voltage from the outside.

[0058] (13) The ion movement measuring method according to (12) above, wherein

[0059] Between the movement process and the detection process, there is a disassembly process in which the electrolyte is disassembled,

[0060] In the detection process, ions of the first atom and the second atom released from a disassembly cross section of the electrolyte are detected.

[0061] According to the present configuration, the movement state of ions can be detected with high precision, as compared with the case in which ions released only from the end surface of the electrolyte, for example, are detected in the case in which

[0062] (14) The ion movement measuring method according to (13) above, wherein in the disassembly process, the electrolyte is disassembled in such a manner that the disassembly cross section extends in a direction connecting the first electrode and the second electrode.

[0063] According to the present configuration, the movement state of ions can be detected in each portion of the direction of movement of ions in the electrolyte.

[0064] (15) The ion movement measuring method according to any one of (12) to (14) above, wherein

[0065] In the detection process, ions released from the end surface of the electrolyte are detected in a state in which the electrolyte is not disassembled,

[0066] The detection process is performed at a plurality of times at which the total time of application of a voltage in the movement process differs from one another.

[0067] According to the present configuration, the moving state of ions can be detected at a plurality of voltage application timings.

[0068] (16) The ion movement measurement method according to (9) or (10) above, wherein in the detection process, ions of the first atom and the second atom are detected at a plurality of points in the test body in a direction from the first electrode side toward the second electrode side,

[0069] The ion movement measurement method further includes:

[0070] a creation process of creating a measured curve that depicts a concentration of ions of the first atom or the second atom at the plurality of points, based on a result of the detection in the detection process;

[0071] a calculation process of calculating, for each of a plurality of diffusion parameters that include a diffusion coefficient of the ions in the test body, a calculation curve that is calculated for the concentration; and

[0072] an estimation process of estimating the diffusion parameter corresponding to the calculated calculation curve that is determined to have the smallest deviation from the measured curve, among the plurality of calculated calculation curves.

[0073] According to the present configuration, the same effects as those of the device of (6) above can be obtained.

[0074] (17) The ion movement measurement method according to (16) above, wherein the diffusion parameters include a diffusion coefficient of the ions that diffuse from the electrolyte to one of the first electrode and the second electrode and a diffusion coefficient of the ions that diffuse from the electrode to the electrolyte.

[0075] According to the present configuration, the same effects as those of the device of (7) above can be obtained.

[0076] (18) The ion movement measurement method according to (9) or (10) above, wherein the electrolyte of the test body has at least one of an active material, a conductive aid, and a binder.

[0077] According to the present configuration, the same effects as those of the device of (8) above can be obtained.

[0078] (EFFECTS OF THE INVENTION)

[0079] According to the device of the aforementioned (1) and the method of the aforementioned (9), the movement state of the second atomic ions at the time of application of the target voltage and the movement state of the second atomic ions due to diffusion can be detected with high precision. Furthermore, according to the structures of the aforementioned (2) to (8) referring to the aforementioned (1) and the structures of the aforementioned (10) to (18) referring to the aforementioned (9), the respective additional effects can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0080] Figure 1 is a diagram illustrating a movement measuring device of ions of the first embodiment.

[0081] Figure 2 is a flowchart illustrating a movement measuring method of ions.

[0082] Figure 3 is a diagram illustrating a manufacturing process.

[0083] Figure 4 is a diagram illustrating a preparation stage of a movement process.

[0084] Figure 5 is a diagram illustrating a movement process.

[0085] Figure 6 is a diagram illustrating an end time of a movement process.

[0086] Figure 7 is a diagram illustrating a disassembly process.

[0087] Figure 8 is a diagram illustrating a detection process.

[0088] Figure 9 is a diagram illustrating an image of analysis in an analysis process.

[0089] Figure 10 is a flowchart illustrating a movement measuring method of ions of the second embodiment.

[0090] Figure 11 is a diagram illustrating a test body and the like of the third embodiment.

[0091] Figure 12 is a diagram illustrating a movement measuring device of ions of the fourth embodiment.

[0092] Figure 13 is a flowchart illustrating a movement measuring method of ions.

[0093] Figure 14 is a graph illustrating a measured curve.

[0094] Figure 15 is a flowchart illustrating details of a calculation process.

[0095] Figure 16 is a graph illustrating the operation curve at the time of placement time of 0.

[0096] Figure 17 is a graph illustrating the operation curve at the time of placement time of a predetermined value.

[0097] Figure 18 is a graph illustrating the operation curve of each diffusion parameter. DETAILED DESCRIPTION

[0098] Hereinafter, an embodiment of the present application will be described with reference to the accompanying drawings. However, the present application is not limited to the following embodiment, and can be appropriately changed within the scope of the gist of the present application.

[0099] [First Embodiment]

[0100] Figure 1 is a schematic view of an ion movement measuring apparatus 100 of the present embodiment. The ion movement measuring apparatus 100 has a test body 10, a movement apparatus 30, a disassembling apparatus 40, a detection apparatus 50, and an analysis apparatus 60. Hereinafter, a lithium 7 atom, i.e., a lithium atom having an atomic weight of 7 is denoted as "7Li", an ion of 7Li is denoted as "7Li+", and a lithium 6 atom, i.e., a lithium atom having an atomic weight of 6 is denoted as "6Li", an ion of 6Li is denoted as "6Li+". In addition, among lithium atoms, the atom having the highest natural abundance is 7Li.

[0101] The test body 10 has a first electrode 11 and a second electrode 12, and an electrolyte 13. The electrolyte 13 is a solid electrolyte, and is disposed between the first electrode 11 and the second electrode 12. More specifically, the electrolyte 13 of the test body 10 is an electrolyte material of a secondary electrode in the present embodiment, but can be, for example, a positive electrode material of a secondary electrode. In this case, the electrolyte 13 of the test body 10 can have, for example, at least one of an active material, a conductive aid, and a binder.

[0102] Either of the first electrode 11 and the second electrode 12 is composed only of lithium. Therefore, between the first electrode 11 and the second electrode 12, a potential difference due to a difference in material is not generated. Therefore, the first electrode 11 and the second electrode 12 become the same potential with each other in a state where no voltage is applied from the outside of the test body 10.

[0103] Specifically, either of the first electrode 11 and the second electrode 12 is also a metal lithium layer that is mainly composed of 6Li. Thus, either of the first electrode 11 and the second electrode 12 contains 6Li at a higher abundance ratio than the natural abundance ratio and contains 7Li at a lower abundance ratio than the natural abundance ratio. More specifically, either of the first electrode 11 and the second electrode 12 is about 95% in 6Li abundance ratio and about 5% in 7Li abundance ratio.

[0104] The mobile device 30 has a switch 31 and a voltage source 33. The positive terminal of the voltage source 33 is electrically connected to the first electrode 11 via the switch 31, and the negative terminal of the voltage source 33 is electrically connected to the second electrode 12 via the second switch 32. Hereinafter, the first switch 31 and the second switch 32 are collectively referred to as "switches 31, 32". In this state, when the switches 31, 32 are turned on, a voltage is applied between the first electrode 11 and the second electrode 12 to make the first electrode 11 side a high potential, and a voltage is applied between the terminals of the electrolyte 13. Thus, within the test body 10, 6Li+and 7Li+move from the first electrode 11 side to the second electrode 12 side.

[0105] The disassembling device 40 is a device for disassembling the test body 10, and has a cutter 44 for cutting the test body 10.

[0106] The detection device 50 has an irradiation section 51 and a detection section 52. The irradiation section 51 promotes the release of 6Li+and 7Li+from the electrolyte 13 by energy irradiation E such as laser irradiation, ion irradiation, electron irradiation, or the like to the electrolyte 13. The detection section 52 detects 6Li+and 7Li+released from the electrolyte 13.

[0107] The analysis device 60 analyzes the movement state of 6Li+within the test body 10 on the basis of 6Li+and 7Li+detected by the detection section 52.

[0108] Figure 2 is a flowchart illustrating an ion movement measurement method using the above ion movement measurement device 100. In the ion movement measurement method, a preparation process S1, a manufacturing process S2, a movement process S3, a disassembling process S4, a detection process S5, and an analysis process S6 are sequentially performed.

[0109] In the preparation process S1, a sulfide solid electrolyte as a material of the electrolyte 13 and a lithium foil as a material of the first electrode 11 and the second electrode 12 are prepared. The lithium foil is mainly composed of 6Li and has a thickness of about 0.1 to 0.4 mm.

[0110] Figure 3is a view illustrating the manufacturing process S2. In order to avoid the chalcogenide solid electrolyte from being in contact with the atmosphere, the manufacturing process S2, the moving process S3, the disassembly process S4, and the detection process S5 shown below are performed in a glove box.

[0111] The manufacturing device 20 has a first pressing portion 21, a second pressing portion 22, and a cylindrical portion 23. In the manufacturing process S2, first, the chalcogenide solid electrolyte is disposed inside the cylindrical portion 23 in a manner of being sandwiched with lithium foils. Next, one lithium foil is pressed against the solid electrolyte with the first pressing portion 21, and another lithium foil is pressed against the solid electrolyte from the opposite side thereof with the second pressing portion 22. In addition, the driving of the first pressing portion 21 and the second pressing portion 22 is performed, for example, with a hydraulic device or the like. Thus, the test body 10 is formed inside the cylindrical portion 23. Then, the pressing of the first pressing portion 21 and the second pressing portion 22 is released, and the test body 10 is taken out of the cylindrical portion 23.

[0112] Figure 4 is a view illustrating a preparation stage of the moving process S3. In this preparation stage, the terminal of the positive electrode side of the moving device 30 is connected to the first electrode 11, and the terminal of the negative electrode side of the moving device 30 is connected to the second electrode 12.

[0113] Figure 5 is a view illustrating the moving process S3. In the moving process S3, the test body 10 is subjected to one or a plurality of times of voltage application by turning on the switches 31, 32. Thus, 6Li+and 7Li+in the test body 10 move from the first electrode 11 side to the second electrode 12 side. Hereinafter, the direction from the first electrode 11 side toward the second electrode 12 side, that is, the moving direction of 6Li+and 7Li+is simply referred to as the "moving direction".

[0114] Figure 6 is a view illustrating the end time of the moving process S3. When the switches 31, 32 are turned off, the test body 10 is no longer subjected to voltage application from the moving device 30, and the movement of 6Li+and 7Li+in the test body 10 stops. Then, the moving device 30 is detached from the test body 10.

[0115] Figure 7 is a view illustrating the disassembly process S4. The electrolyte 13 is disassembled by cutting the test body 10 with the cutter 44 of the disassembly device 40. At this time, the electrolyte 13 is disassembled in a manner of making the disassembly cross section D of the test body 10 a face extending in the moving direction. Then, the disassembly cross section D is processed to be smooth with a cooled ion milling.

[0116] Figure 8is a graph illustrating the detection process S5 and the analysis process S6. In the detection process S5, first, sputtering for removing damage caused by the aforementioned ion milling is performed on the disassembled section D. Then, the disassembled section D of the electrolyte 13 is subjected to energy irradiation E with the irradiation section 51 to promote the release of 6Li+and 7Li+, and the released 6Li+and 7Li+are detected with the detection section 52. At this time, using an analysis method capable of analyzing the mass difference of isotopes such as Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS), or the like, 6Li+and 7Li+are distinguished from each other.

[0117] In the analysis process S6, the analysis device 60 analyzes the movement state of 6Li+within the test piece 10 based on 6Li+and 7Li+detected by the detection section 52.

[0118] Figure 9 is a graph of an image illustrating the analysis in the analysis process S6. The horizontal axis of the graph indicates the position in the movement direction within the electrolyte 13. On the other hand, the vertical axis indicates the ratio of 6Li+to 7Li+detected at the position in the movement direction. Hereinafter, the ratio of 6Li+to 7Li+detected will be referred to as "6Li+ / 7Li+".

[0119] From this Figure 9 As is clear from the graph of 6Li+ / 7Li+, 6Li+ / 7Li+of about 8% in nature is about 50% or more in the entire region of the movement direction within the electrolyte 13. From this, it is known that 6Li+reaches the entire region of the movement direction within the electrolyte 13 from the first electrode 11. On the other hand, for example, when 6Li+ / 7Li+is about 8% in the entire region or a part of the region of the movement direction within the electrolyte 13, it is known that 6Li+does not reach the part from the first electrode 11.

[0120] The advantages of this embodiment are summarized below. According to this embodiment, it is possible to distinguish and observe 6Li+ and 7Li+ moving from the first electrode 11 to the electrolyte 13 based on their mass difference. Furthermore, by applying a voltage between the first electrode 11 and the second electrode 12 from outside the test body 10 using the moving device 30, a voltage at a target time can be applied between the terminals of the electrolyte 13. Moreover, since both the first electrode 11 and the second electrode 12 are metallic lithium, they are at the same potential when no voltage is applied from outside the test body, so there is no need to worry about applying an unexpected voltage between the terminals of the electrolyte 13. Therefore, the movement state of 6Li+ at the time the target voltage is applied can be detected with high precision.

[0121] Furthermore, in the detection step S5, 6Li+ and 7Li+ released from the electrolyte 13 are detected without applying voltage to the test body 10 from the outside. Therefore, compared with the case where voltage is applied to the test body 10 and 6Li+ and 7Li+ released from the electrolyte 13 are detected simultaneously, the movement state of 6Li+ can be easily detected at the moment the target voltage is applied.

[0122] Furthermore, in the disassembly step S4, the electrolyte 13 is disassembled, and in the detection step S5, 6Li+ and 7Li+ released from the disassembly section D of the electrolyte 13 are detected. Therefore, compared to detecting ions released only from the end face of the electrolyte 13 without disassembling it, the movement state of 6Li+ can be detected with high precision.

[0123] Furthermore, in the disassembly step S4, the electrolyte 13 is disassembled in such a way that the disassembly section D extends in the moving direction. Therefore, the movement state of 6Li+ can be detected in each part of the electrolyte 13 in the moving direction.

[0124] Furthermore, the second electrode 12 contains 6Li+ and 7Li+ in the same abundance ratio as the first electrode 11. Therefore, the first electrode 11 and the second electrode 12 can be manufactured from the same material, i.e., the same lithium metal foil. Thus, the manufacture of the test specimen 10 becomes easier.

[0125] [Second Implementation]

[0126] Next, the second embodiment will be described. The following embodiments will be based on the first embodiment and will focus on the differences from the first embodiment. Points that are the same as or similar to the first embodiment will be omitted from the description as appropriate.

[0127] Figure 10 This is a flowchart illustrating the ion movement measurement method of this embodiment. The difference between this embodiment and the first embodiment is the absence of the disassembly step S4, the repeated movement step S3, the detection step S5, and the analysis step S6.

[0128] In the detection process S5, the end surface of the electrolyte 13 is subjected to energy irradiation E by the irradiation section 51 in a state where the electrolyte 13 is not disassembled, and 6Li+and 7Li+released from the end surface of the electrolyte 13 are detected. Specifically, in the present embodiment, the movement process S3 is temporarily ended, and the detection process S5 is performed in a state where the voltage is not applied to the test body 10 from the movement device 30. However, instead of this, the detection process S5 can be performed simultaneously with the movement process S3, that is, while the voltage is applied to the test body 10.

[0129] After the detection process S5, the analysis process S6 is performed as in the case of the first embodiment. After the analysis process S6, it is determined in S7 whether the movement process S3, the detection process S5, and the analysis process S6 have been performed a prescribed number of times. When the determination is negative, the movement process S3, the detection process S5, and the analysis process S6 are repeated. On the other hand, when the determination is affirmative in S5, the flow is ended.

[0130] According to the present embodiment, by repeating the movement process S3, the detection process S5, and the analysis process S6, the detection process S5 is performed at a plurality of times when the total time of voltage application in the movement process S3 is different from each other. Therefore, the movement state of 6Li+can be detected at a plurality of times of voltage application.

[0131] [Third Embodiment]

[0132] Figure 11 is a view illustrating a test body 10 and the like of the third embodiment. In the present embodiment, the second electrode 12 is mainly composed of 7Li, instead of 6Li. Therefore, the second electrode 12 contains 7Li at a higher abundance ratio than that of 6Li in the first electrode 11, and contains 6Li at a lower abundance ratio than that of 6Li in the first electrode 11. Specifically, for example, the second electrode 12 can contain 6Li and 7Li at a natural abundance ratio, respectively, or can be composed of 7Li substantially only.

[0133] According to the present embodiment, since the first electrode 11 contains 6Li at a higher abundance ratio than the second electrode 12, it is easy to determine that the increase of 6Li+in the electrolyte 13 is due to the movement of 6Li+from the first electrode 11 side.

[0134] [Fourth Embodiment]

[0135] Figure 12is a mode diagram illustrating the ion movement measuring apparatus 100 of the fourth embodiment. The fourth embodiment differs from the first embodiment in that the ion movement measuring apparatus 100 does not have the movement apparatus 30 described in the first embodiment, and the analysis apparatus 60 has a creator 61, a calculator 62, and an estimator 63. In the fourth embodiment, one computer includes the creator 61, the calculator 62, and the estimator 63. However, instead, for example, the creator 61, the calculator 62, and the estimator 63 can be respectively constituted by different computers.

[0136] Figure 13 is a flowchart illustrating the ion movement measuring method of the fourth embodiment. The ion movement measuring method of the fourth embodiment differs from the first embodiment in the following points. First, the ion movement measuring method differs from the first embodiment in that the ion movement measuring method has the placement procedures S3a, S3b instead of the movement procedure S3. Further, the ion movement measuring method differs from the first embodiment in that the ion movement measuring method has the creation procedure S6a, the calculation procedure S6b, and the estimation procedure S6c instead of the analysis procedure S6. Further, the ion movement measuring method differs from the first embodiment in that the ion movement measuring method has the placement time confirmation procedure S7 after the estimation procedure S6c.

[0137] The preparation procedure S1 and the manufacturing procedure S2 are the same as in the case of the first embodiment. In the placement procedure S3a, the test body 10 is placed for a prescribed placement time t of, for example, 2 days, 4 days, or the like, without applying a voltage between the first electrode 11 and the second electrode 12. The disassembly procedure S4 is the same as in the case of the first embodiment.

[0138] Hereinafter, the direction from the first electrode 11 side toward the aforementioned second electrode 12 side, that is, the movement direction described in the first embodiment, will be referred to as a "diffusion direction X". The detection procedure S5 of the fourth embodiment differs from the case of the first embodiment in that the detection apparatus 50 detects 6Li+ in the range including the electrolyte 13 and the diffusion direction X of the first electrode 11.

[0139] Hereinafter, a curve that depicts the concentration of 6Li+ at a plurality of points in the diffusion direction X will be simply referred to as a "curve", a curve based on a measured value will be referred to as a "measured curve Pa", and a curve based on calculation will be referred to as a "calculated curve Pc".

[0140] In the creation procedure S6a, the creator 61 creates the measured curve Pa based on the detection result in the detection procedure S5. Hereinafter, the diffusion coefficient of 6Li+ that diffuses from the electrolyte 13 toward the first electrode 11 will be referred to as an "electrode diffusion coefficient DLi", and the diffusion coefficient of 6Li+ that diffuses from the first electrode 11 toward the electrolyte 13 will be referred to as an "electrolyte diffusion coefficient Dse". In addition, hereinafter, the combination of the electrode diffusion coefficient DLi and the electrolyte diffusion coefficient Dse will be referred to as "diffusion parameters DLi, Dse".

[0141] In the calculation process S6b, the calculator 62 calculates the operation curve Pc for each of the diffusion parameters DLi, Dse using the plurality of diffusion parameters DLi, Dse. Details of the calculation method will be described below.

[0142] In the estimation process S6c, the estimator 63 estimates the operation curve Pc that is judged to have the smallest deviation from the measured curve Pa among the plurality of calculated operation curves Pc. Details of the estimation method will be described below. Also, the estimator 63 estimates the diffusion parameters DLi, Dse corresponding to the estimated operation curve Pc.

[0143] In the placement time confirmation process S7, it is determined whether or not the accumulated time of the placement time t reaches a prescribed time. When the determination is negative N, the same placement process S3b as the placement process S3a is performed, and then the flow returns to the detection process S5. On the other hand, when the determination is affirmative Y in the placement time confirmation process S7, the flow ends.

[0144] Figure 14 is an example of the measured curve Pa created in the creation process S6a. The broken line indicates the measured curve Pa at the placement time t of 2 days, and the solid line indicates the measured curve Pa at the placement time t of 4 days.

[0145] Figure 15 is an example of the measured curve Pa created in the creation process S6a. The broken line indicates the measured curve Pa at the placement time t of 2 days, and the solid line indicates the measured curve Pa at the placement time t of 4 days. Figure 13 is a flowchart illustrating details of the calculation process S6b shown in FIG. 6. Hereinafter, with respect to the electrode diffusion coefficient DLi, the lower limit value of the range that can become real is referred to as "lower limit value DLiL", and the upper limit value of the range that can become real is referred to as "upper limit value DLiU". Also, with respect to the electrolyte diffusion coefficient Dse, the lower limit value of the range that can become real is referred to as "lower limit value DseL", and the upper limit value of the range that can become real is referred to as "upper limit value DseU".

[0146] First, in S61, the electrode diffusion coefficient DLi is set to the lower limit value DLiL. Next, in S62, it is determined whether or not the electrode diffusion coefficient DLi is below the upper limit value DLiU. When the determination is affirmative Y, in S63, the electrolyte diffusion coefficient Dse is set to the lower limit value DseL.

[0147] Next, in S64, it is determined whether or not the electrolyte diffusion coefficient Dse is below the upper limit value DseU. When the determination is affirmative Y, in S65, the operation curve Pc is calculated based on the current diffusion parameters DLi, Dse. Details of the calculation will be described below. Next, in S66, the deviation of the calculated operation curve Pc from the measured curve Pa is calculated. Details of the calculation will be described below.

[0148] Next, in S67, after the electrolyte diffusion coefficient Dse is increased by a prescribed value, the routine returns to S64. Then, as long as the determination in S64 is affirmative Y, that is, as long as the electrolyte diffusion coefficient Dse is below the upper limit value DseU, S64 to 67 are repeated.

[0149] On the other hand, when the determination in S64 is negative N, that is, when the electrolyte diffusion coefficient Dse exceeds the upper limit value, the routine proceeds to S68, the electrode diffusion coefficient DLi is increased by a prescribed value, and the routine returns to S62. Then, as long as the determination in S62 is affirmative Y, that is, as long as the electrode diffusion coefficient DLi is below the upper limit value DLiU, S62 to 68 are repeated.

[0150] On the other hand, when the determination in S62 is negative N, that is, when the electrode diffusion coefficient DLi exceeds the upper limit value DLiU, the routine proceeds to the estimation process S6c.

[0151] Next, the calculation of the operation curve Pc in S65 shown in Figure 16 and Figure 17 will be described. Figure 15

[0152] Figure 16 is a graph illustrating the operation curve Pc in the initial state where the standing time is "0". Hereinafter, the ratio of 6Li+ to the total lithium ions including 6Li+ and 7Li+ will be referred to as the "concentration of 6Li+". Thus, in the initial state, it is assumed that the concentration of 6Li+ in the first electrode 11 is constant at a prescribed initial concentration CLi of, for example, 95%, and the concentration of 6Li+ in the electrolyte 13 is constant at a prescribed initial concentration Cse of, for example, 7.5% as the natural abundance ratio.

[0153] According to this state, it is assumed that 6Li+ in the first electrode 11 diffuses into the electrolyte 13 in accordance with the electrode diffusion coefficient DLi, and 6Li+ in the electrolyte 13 diffuses into the first electrode 11 in accordance with the electrolyte diffusion coefficient Dse.

[0154] Figure 17 is a graph illustrating the operation curve Pc in a prescribed state where the standing time t is 2 days. Hereinafter, the curve based on the diffusion of 6Li+ from the first electrode 11 to the electrolyte 13 will be referred to as the "first curve Pc1", and the curve based on the diffusion of 6Li+ from the electrolyte 13 to the first electrode 11 will be referred to as the "second curve Pc2". The operation curve Pc is the sum of these first curve Pc1 and second curve Pc2.

[0155] Specifically, the first curve Pc1 can be calculated based on the following formula 1, and the second curve Pc2 can be calculated based on the following formula 2.

[0156] [Formula 1] ​

[0157]

[0158] [Num 2]

[0159]

[0160] In these Formula 1, Formula 2, "C(x, t)" is the concentration of 6Li+ at "x" "t". "erf" indicates an error function. Hereinafter, the boundary of the first electrode 11 and the electrolyte 13 is referred to as "boundary B". "x" indicates the position of the diffusion direction X. "xb" indicates the position of the diffusion direction X of the boundary B. "t" is the placement time t. As this placement time t, the same placement time t as in the case of the measured curve Pa is adopted. That is, the placement time t at the time when 6Li+ is detected in the detection process is adopted. "CLi" is the initial concentration CLi of 6Li+ within the first electrode 11. "Cse" is the initial concentration Cse of 6Li+ within the electrolyte 13.

[0161] Next, the calculation of the deviation in S66 shown in FIG. 6 will be described with reference to FIG. 7. Figure 18 Figure 15 The three curves of FIG. 7 respectively indicate the calculated curves Pc in the case where the electrode diffusion coefficient DLi and the electrolyte diffusion coefficient Dse are relatively large, relatively small, and intermediate. Figure 18 For each of the calculated curves Pc, the calculation of the deviation in S66 is performed using the least square method in the boundary region Rb. That is, the difference between the concentration of 6Li+ in the calculated curve Pc and the concentration of 6Li+ in the measured curve Pa is calculated at a plurality of points in the diffusion direction X in the boundary region Rb. The sum of the squares of the differences at these points is stored as a deviation parameter indicating the magnitude of the deviation.

[0162] Further, in the estimation process S6c, the calculated curve Pc having the smallest deviation parameter described above is estimated. Further, the diffusion parameters DLi, Dse corresponding to the estimated calculated curve Pc are estimated.

[0163]

[0164] The analysis device 60 shown in FIG. 6 displays the estimated diffusion parameters DLi, Dse on, for example, a display, or inputs them into a computer or a memory constituting at least a part of the analysis device 60, or outputs them into a computer or a memory located outside the analysis device 60. Figure 12

[0165] ​​Next, the use of the calculated diffusion parameters DLi, Dse will be described. Based on the calculated electrode diffusion coefficient DLi and electrolyte diffusion coefficient Dse, the aforementioned formula 1 and formula 2, and the required standing time t, the diffusion state of 6Li+ after the test body 10 is left for the required standing time t can be estimated.

[0166] Specifically, based on the calculated electrode diffusion coefficient DLi, the aforementioned formula 1, and the required standing time t, the first curve P1 in the state after the test body 10 is left for the required standing time t can be calculated. In addition, based on the calculated electrolyte diffusion coefficient Dse, the aforementioned formula 2, and the required standing time t, the second curve P2 in the state after the test body 10 is left for the required standing time t can be calculated. The operation curve Pc in the state after the test body 10 is left for the required standing time t is calculated based on the sum of these first curve P1 and second curve P2. Thereby, the diffusion state of 6Li+ in the state after the test body 10 is left for the required standing time t can be estimated.

[0167] Further, the calculated diffusion parameters DLi, Dse can be temperature-corrected based on the following formula 3, formula 4.

[0168] [Equation 3]

[0169] DLi = A exp(-QLi / RT) (Formula 3)

[0170] [Equation 4]

[0171] Dse = A exp(-Qse / RT) (Formula 4)

[0172] In the aforementioned formula 3 and formula 4, "A" is a frequency factor. "QLi" is the activation energy QLi of 6Li+ within the first electrode 11, and "Qse" is the activation energy Qse of 6Li+ within the electrolyte 13. "R" is the gas constant. "T" is the absolute temperature of the test body 10.

[0173] Regarding the above correction, in detail, as follows. Based on the calculated electrode diffusion coefficient DLi, the temperature T corresponding to the measured curve Pa and the operation curve Pc used in the calculation, and the aforementioned formula 3, the activation energy QLi can be calculated. From the calculated activation energy QLi, the aforementioned formula 3, and the required temperature T, the electrode diffusion coefficient DLi at the required temperature T can be inversely calculated. As described above, the electrolyte diffusion coefficient Dse at the required temperature T can be calculated. From the above, the diffusion parameters DLi, Dse at the required temperature T can be estimated. That is, the diffusion parameters DLi, Dse can be temperature-corrected.

[0174] The configuration and effects of the present embodiment are summarized below.

[0175] In the present embodiment, as in the case of the first embodiment, the first electrode 11 and the second electrode 12 are also the same potential, and thus, there is no concern that an unintended voltage is applied between the terminals of the electrolyte 13. In this case, in the detection process S5, the 6Li+is detected at a plurality of points in the diffusion direction X in the test body 10. Also, in the creation process S6a, the measured curve Pa is created based on the detection result in the detection process S5. Thus, the movement due to the diffusion of the 6Li+can be detected with high precision, and the measured curve Pa can be created with high precision without being affected by the unintended voltage.

[0176] Also, in the estimation process S6c, the operation curve Pc that is judged to have the smallest deviation from the measured curve Pa is estimated, and the diffusion parameters DLi, Dse corresponding to the operation curve Pc are estimated. Thus, according to the estimated diffusion parameters DLi, Dse, the operation curve Pc at the time when the conditions such as the placement time t and the temperature T are changed can be inversely calculated. Thus, the diffusion state of the 6Li+at the time when the conditions are changed can be estimated. Thus, it will be possible to estimate the state of the secondary electrode such as the lithium ion concentration in a specific layer, the charge and discharge capacity, and the like under the desired conditions, and further, it will be possible to optimally set and optimally control the secondary electrode.

[0177] [Other Embodiments]

[0178] The above embodiments can be implemented, for example, by being changed as follows. The electrolyte 13 can be a liquid electrolyte, or can be constituted by both a solid electrolyte and a liquid electrolyte.

[0179] In addition, the first electrode 11 and the second electrode 12 can also be formed by laminating metallic lithium on base members of the same material as each other such as stainless steel. Even in this case, since a potential difference due to a difference in material does not occur between the first electrode 11 and the second electrode 12, the first electrode 11 and the second electrode 12 become the same potential as each other in a state where no voltage is applied to the test body 10 from the outside.

[0180] In addition, the first electrode 11 and the second electrode 12 can also be constituted by an element other than metallic lithium, and in the detection process S5, the first atomic ion of the element and the second atomic ion of the isotope thereof can also be distinguished.

[0181] In addition, in the fourth embodiment, a curve of the concentration of 7Li+may be calculated instead of the curve of the concentration of 6Li+. In addition, in the fourth embodiment, the deviation parameter can be calculated using a method other than the least square method. Specifically, for example, the sum of the absolute values of the differences of the points can be set as the deviation parameter. In addition, in the fourth embodiment, the calculation of the curve Pc can be performed using Equation 1, Equation 2, which represent the interdiffusion when two different metals are joined, but can also be performed using another equation or model that represents diffusion.

[0182] Reference Signs

[0183] 6Li+Lithium 6 atom ion as ion of second atom

[0184] 7Li+Lithium 7 atom ion as ion of first atom

[0185] 10 Test body

[0186] 11 First electrode

[0187] 12 Second electrode

[0188] 13 Electrolyte

[0189] 30 Moving device

[0190] 40 Disassembling device

[0191] 50 Detecting device

[0192] 61 Creator

[0193] 62 Calculator

[0194] 63 Estimator

[0195] 100 Ion movement measuring device

[0196] S3 Moving step

[0197] S3a Placing step

[0198] S4 Disassembling step

[0199] S5 Detecting step

[0200] S6a Creating step

[0201] S6b Calculating step

[0202] S6c Estimating step

Claims

1. An ion movement measuring apparatus comprising: a test body having a first electrode and a second electrode, and an electrolyte disposed between the first electrode and the second electrode, the first electrode and the second electrode having a layer of the same element as each other, being the same potential as each other in a state where no voltage is applied from the outside to the test body, and at least the first electrode containing a first atom and a second atom, which are the highest and second highest in natural abundance ratio among the elements, at a higher abundance ratio than the natural abundance ratio of the second atom of the isotope; and a detection apparatus that detects ions of the first atom and the second atom released from the electrolyte.

2. The ion movement measuring apparatus according to claim 1, wherein the ion movement measuring apparatus has a movement apparatus that causes the ions of the first atom and the second atom to move from the first electrode side to the second electrode side in the test body by applying a voltage between the first electrode and the second electrode to form a high potential on the first electrode side.

3. The ion movement measuring apparatus according to claim 1 or 2, wherein the electrolyte is a solid electrolyte, the same element is lithium, the first atom is a lithium-7 atom, and the second atom is a lithium-6 atom.

4. The apparatus according to claim 1 or 2, wherein the second electrode contains the second atom at a higher abundance ratio than the natural abundance ratio of the second atom.

5. The apparatus according to claim 1 or 2, wherein the second electrode contains the first atom at a higher abundance ratio than the abundance ratio of the first atom in the first electrode, and contains the second atom at a lower abundance ratio than the abundance ratio of the second atom in the first electrode.

6. The ion movement measuring apparatus according to claim 1 or 2, wherein the detection apparatus detects ions of the first atom and the second atom at a plurality of points in the test body in a direction from the first electrode side toward the second electrode side, the ion movement measuring apparatus further has: a creator that creates a measured curve that depicts a concentration of the ions of the first atom or the second atom at the plurality of points, based on a detection result of the detection apparatus; a calculator that calculates, for each of a plurality of diffusion parameters including a diffusion coefficient of the ions in the test body, a calculation curve calculated for the concentration, using the diffusion parameter; and an estimator that estimates the calculation curve of the plurality of calculated calculation curves that is determined to have the smallest deviation from the measured curve, thereby estimating the diffusion parameter corresponding to the estimated calculation curve.

7. The ion movement measuring apparatus according to claim 6, wherein the diffusion parameters include a diffusion coefficient of the ions diffusing from the electrolyte to one of the first electrode and the second electrode, and a diffusion coefficient of the ions diffusing from the electrode to the electrolyte.

8. The apparatus according to claim 1 or 2, wherein the electrolyte of the test body has at least one of an active material, a conductive aid, and a binder.

9. An ion movement measuring method using a test body, The test body has a first electrode and a second electrode, and an electrolyte disposed between the first electrode and the second electrode, the first electrode and the second electrode have layers of the same element as each other, are the same potential as each other in a state where no voltage is applied to the test body from the outside, and at least the first electrode contains a first atom and a second atom of the element having the highest natural abundance ratio, the first atom having a higher abundance ratio than the natural abundance ratio of the second atom of the isotope; The ion movement measurement method has: a detection step of detecting ions of the first atom and the second atom released from the electrolyte.

10. The ion movement measurement method according to claim 9, wherein The ion movement measurement method has: a movement step of causing ions of the first atom and the second atom to move from the first electrode side to the second electrode side in the test body by applying a voltage between the first electrode and the second electrode from the outside of the test body to make the first electrode side a high potential, the detection step is after or during the movement step, and detects ions of the first atom and the second atom released from the electrolyte.

11. The ion movement measurement method according to claim 9 or 10, wherein the electrolyte is a solid electrolyte, the same element is lithium, the first atom is a lithium-7 atom, and the second atom is a lithium-6 atom.

12. The method of claim 10, wherein, The detection step is performed in a state where no voltage is applied to the test body from the outside after the movement step.

13. The ion movement measurement method according to claim 12, wherein between the movement step and the detection step, there is a disassembly step of disassembling the electrolyte, in the detection step, ions of the first atom and the second atom released from a disassembled cross section of the electrolyte are detected.

14. The method of measuring movement of ions according to claim 13, wherein, In the disassembly step, the electrolyte is disassembled in a manner such that the disassembled cross section extends in a direction connecting the first electrode and the second electrode.

15. The ion movement measurement method according to any one of claims 12 to 14, wherein in the detection step, ions released from an end surface of the electrolyte are detected in a state where the electrolyte is not disassembled, the detection step is performed at a plurality of times at which a total time of the applied voltage in the movement step is different from each other.

16. The ion movement measurement method according to claim 9 or 10, wherein in the detection step, ions of the first atom and the second atom are detected at a plurality of points in a direction from the first electrode side toward the second electrode side in the test body, the ion movement measurement method further has: a creation step of creating a measured curve that depicts a concentration of ions of the first atom or the second atom at the plurality of points, based on a result of the detection in the detection step; a calculation step of calculating, for each of a plurality of diffusion parameters including a diffusion coefficient of the ions in the test body, a calculation curve calculated for the concentration, and a determination step of determining whether or not the test body is normal based on a result of the calculation in the calculation step. The estimation process estimates the diffusion parameter corresponding to the estimated operation curve from among the plurality of calculated operation curves by determining which of the operation curves has the smallest deviation from the measured curve.

17. The method of mobility determination of ions according to claim 16, wherein, The diffusion parameter includes a diffusion coefficient of the ions diffusing from the electrolyte to one of the first electrode and the second electrode and a diffusion coefficient of the ions diffusing from the electrode to the electrolyte.

18. The method according to claim 9 or 10, wherein, The electrolyte of the test body has at least one of an active material, a conductive aid, and a binder.

Images