Cell for analysis and x-ray diffraction device

Abstract

To provide a cell for analysis that can be used for XRD analysis.SOLUTION: An X-ray transmission window material 14 includes a resin film. A second exterior body 12 held between a first exterior body 11 and a third exterior body 13 is in contact with the third exterior body through an O-ring. The first exterior body includes a first opening 21. The second exterior body includes a second opening 22 whose area is smaller than that of the first opening. The second opening exists inside the first opening. In a space surrounded by the first exterior body, the second exterior body, the third exterior body, and the O-ring, the X-ray transmission window material, a multilayer body, a pedestal, and a spring are provided at a position overlapping with the second opening. The X-ray transmission window material is fixed to a surface of the second exterior body on the space side so as to cover the entire second opening. The multilayer body is held by the X-ray transmission window material and the pedestal. The pedestal is in contact with the third exterior body through the spring. The multilayer body includes a lithium metal negative electrode, a separator, and a positive electrode in order from the X-ray transmission window material to the pedestal. The lithium metal negative electrode includes a region in contact with the second exterior body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One aspect of the present invention relates to an analytical cell, an analytical method, or a method for manufacturing an analytical cell, or to an X-ray diffraction (XRD) device having the analytical cell, a measurement method for the X-ray diffraction device using the analytical cell, or a method for manufacturing an X-ray diffraction device using the analytical cell. [Background technology]

[0002] In recent years, various types of power storage devices have been actively developed, such as lithium-ion secondary batteries, lithium-ion capacitors, air batteries, all-solid-state batteries, etc. In particular, the demand for high-output, high-capacity lithium-ion secondary batteries has rapidly expanded in line with the development of the semiconductor industry, and they have become indispensable in the modern information society as a rechargeable energy source.

[0003] In particular, there is a high demand for lithium ion secondary batteries with large discharge capacity per weight and excellent cycle characteristics for use in mobile electronic devices, etc. In order to meet this demand, there has been active improvement of the positive electrode active material in the positive electrode of lithium ion secondary batteries, and research on the crystal structure of the positive electrode active material is also being conducted (Patent Document 1).

[0004] Known methods for analyzing the crystal structure of active materials include XRD, electron beam diffraction, neutron diffraction, etc. Among them, XRD allows for in-situ analysis (also called operando analysis) in which a cell incorporating an electrode made from the active material to be analyzed is analyzed while being charged or discharged, and improvements to analytical cells for in-situ XRD analysis are also being made (Patent Document 2, Non-Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication 2018-195581 [Patent Document 2] Patent Publication No. 2019-2887 [Non-patent literature]

[0006] [Non-Patent Document 1] GG Amatucci, JM Tarascon, LC Klein, “CoO2, The End Member of the LiCoO2 Solid Solution”, Journal of The Electrochemical Society, 143(3), 1114,1996 Summary of the Invention [Problem to be solved by the invention]

[0007] Analytical cells for in-situ XRD analysis are commercially available from manufacturers of XRD devices, and there are also cases where proprietary analytical cells have been developed, such as in Patent Document 2.

[0008] Regarding the X-ray transmission window material of an analytical cell for in-situ XRD analysis, analytical cells sold by manufacturers of XRD devices often use beryllium. However, X-ray transmission window materials using beryllium are easily damaged, and there is a concern that the X-ray transmission window material using beryllium may cause health damage if it is altered to beryllium oxide. Therefore, Patent Document 2 discloses an X-ray transmission window material that does not use beryllium, which is constructed by sandwiching aluminum foil between two sheets of polyimide resin and bonding them together with epoxy resin.

[0009] In the configuration of Patent Document 2, the X-ray transmission window material contains aluminum foil, so that in XRD measurement, the diffraction peaks derived from aluminum are included in the measurement data. Measurement data containing the diffraction peaks derived from aluminum may hinder the analysis of the crystal structure of the positive electrode active material such as lithium cobalt oxide and lithium nickel-cobalt-manganese oxide. For example, the (111) diffraction derived from the aluminum foil and the (006) diffraction and (10-2) diffraction of lithium cobalt oxide are both observed around 2θ=38.5°. In addition, the (200) diffraction of aluminum foil and the (104) diffraction of lithium cobalt oxide are both observed near 2θ=45.0°. In addition, the (220) diffraction of aluminum foil and the (108) diffraction of lithium cobalt oxide are both observed near 2θ=65.0°. Therefore, when attempting to detect a weak diffraction peak originating from lithium cobalt oxide, the diffraction peak of the lithium cobalt oxide and the diffraction peak of the aluminum foil may overlap, hindering the analysis.

[0010] Therefore, it is preferable that the XRD measurement data used for analyzing the crystal structure of the positive electrode active material such as lithium cobalt oxide, lithium nickel-cobalt-manganese oxide, etc. does not include a diffraction peak derived from aluminum. In other words, it is preferable that the analytical cell used for XRD measurement of the crystal structure of the positive electrode active material such as lithium cobalt oxide, lithium nickel-cobalt-manganese oxide, etc. does not have aluminum in the X-ray transmission window material.

[0011] In view of the above, an object of one embodiment of the present invention is to provide an analytical cell having an X-ray transmission window material that does not contain beryllium and aluminum. Alternatively, an object of one embodiment of the present invention is to provide an analytical cell having an X-ray transmission window material that does not contain a metal material. Alternatively, an object of one embodiment of the present invention is to provide an analytical cell having an X-ray transmission window material made of a resin film. Alternatively, an object of one embodiment of the present invention is to provide an analytical cell having an X-ray transmission window material made of a polyimide film. Alternatively, an object of one embodiment of the present invention is to provide an analytical cell in an XRD device that does not contain a metal material other than lithium metal in an X-ray irradiation path and reflection path.

[0012] Incidentally, no consideration is given to the effect on in-situ XRD analysis of gas generated in the analytical cell when the conventional analytical cell is charged to a high voltage of 4.5 V or more, for example, 4.55 V or more, 4.60 V or more, 4.65 V or more, 4.70 V or more, 4.75 V or more, or 4.80 V or more. For example, in the structure of a conventional analytical cell, simply replacing an X-ray transmission window material that does not contain beryllium and aluminum with a polymer film as the X-ray transmission window material may cause the polymer film to deform due to the gas generated in the analytical cell, which may interfere with XRD measurement.

[0013] In view of the above, an object of one embodiment of the present invention is to provide an analytical cell in which deformation of the X-ray transmission window material is suppressed by gas generated in the analytical cell even when a polymer film is used as the X-ray transmission window material. Alternatively, an object of one embodiment of the present invention is to provide an analytical cell in which deformation of the X-ray transmission window material is suppressed by gas generated in the analytical cell even when a metal material is not used as the X-ray transmission window material.

[0014] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that it is possible to extract problems other than these from the description of the specification, drawings, and claims. [Means for solving the problem]

[0015] One aspect of the present invention is an analytical cell having a first exterior body, a second exterior body, a third exterior body, an O-ring, an X-ray transparent window material, a laminate, a base, and a spring, in which the X-ray transparent window material has a resin film, the second exterior body sandwiched between the first exterior body and the third exterior body is in contact with the third exterior body via the O-ring, the first exterior body has a first opening, the second exterior body has a second opening having an area smaller than the first opening, the second opening is located inside the first opening, and the first exterior body, the second exterior body, and the third exterior body and an O-ring, the X-ray transparent window material, the laminate, the base, and the spring are provided in a position overlapping with the second opening, the X-ray transparent window material is fixed to the space-side surface of the second exterior body so as to cover the entire second opening, the laminate is sandwiched between the X-ray transparent window material and the base, the base is in contact with the third exterior body via the spring, and the laminate has, from the X-ray transparent window material toward the base, a lithium metal negative electrode, a separator, and a positive electrode, in that order, and the lithium metal negative electrode has an area in contact with the second exterior body.

[0016] In the above, the resin film preferably contains polyimide.

[0017] Another aspect of the present invention is an X-ray diffraction instrument having any one of the analytical cells described above.

[0018] Furthermore, it is preferable that the X-ray diffraction apparatus has an X-ray source and an X-ray detector, the X-rays irradiated from the X-ray source are reflected inside the analytical cell and the reflected X-rays are measured by the X-ray detector, and the shape of the second opening is a rectangle with its long side in the direction connecting the X-ray source and the X-ray detector.

[0019] In the above, it is preferable that the rectangular shape of the second opening has a short side of 2.2 mm or more and 5.0 mm or less and a long side of 6.0 mm or more and 10.0 mm or less.

[0020] The rectangular shape of the second opening is preferably a rounded rectangle with short sides of 2.2 mm to 5.0 mm and long sides of 6.0 mm to 10.0 mm, the corners having a radius equal to half the length of the short sides. Effect of the Invention

[0021] According to one embodiment of the present invention, an analytical cell having an X-ray transmission window material free of beryllium and aluminum can be provided. Alternatively, according to one embodiment of the present invention, an analytical cell having an X-ray transmission window material free of a metal material can be provided. Alternatively, according to one embodiment of the present invention, an analytical cell having an X-ray transmission window material made of a resin film can be provided. Alternatively, according to one embodiment of the present invention, an analytical cell having an X-ray transmission window material made of a polyimide film can be provided. Alternatively, according to one embodiment of the present invention, an analytical cell having an X-ray transmission window material free of a crystalline material can be provided. Alternatively, according to one embodiment of the present invention, an object of the present invention is to provide an analytical cell having no metal material other than lithium metal in the X-ray irradiation path and reflection path in an XRD device.

[0022] According to one aspect of the present invention, an analytical cell can be provided in which deformation of the X-ray transmission window material is suppressed by gas generated in the analytical cell even when a polymer film is used as the X-ray transmission window material, or in which deformation of the X-ray transmission window material is suppressed by gas generated in the analytical cell even when a metal material is not used as the X-ray transmission window material.

[0023] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract effects other than these from the description in the specification, drawings, claims, etc. [Brief description of the drawings]

[0024] [Figure 1] 1(A) and 1(B) are diagrams illustrating an analytical cell according to one embodiment of the present invention. [Diagram 2] 2(A) and 2(B) are diagrams illustrating an analytical cell according to one embodiment of the present invention. [Diagram 3] 3(A) and 3(B) are diagrams illustrating an analytical cell according to one embodiment of the present invention. [Figure 4] 4A to 4F are diagrams illustrating an analytical cell according to one embodiment of the present invention. [Diagram 5] 5(A) and 5(B) are diagrams illustrating an X-ray diffraction apparatus according to one embodiment of the present invention. [Figure 6] 6(A) and 6(B) are diagrams illustrating an analytical cell according to one embodiment of the present invention. [Figure 7] 7(A) to 7(E) are diagrams illustrating the analytical cell prepared in the examples. [Figure 8] 8(A) and 8(B) are diagrams illustrating the results of XRD measurement using the analytical cell prepared in the example. [Figure 9] 9(A) and 9(B) are diagrams illustrating the results of XRD measurement using the analytical cell prepared in the example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] In the following, examples of embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention should not be interpreted as being limited to the following examples. The embodiments of the present invention can be modified without departing from the spirit of the present invention.

[0026] In this specification, the space group is expressed using the short notation of the international notation (or Hermann-Mauguin notation). Also, the crystal plane and crystal direction are expressed using Miller indices. Individual planes indicating crystal planes are expressed using (). In crystallography, the numbers are marked with a superscript bar when notating space groups, crystal planes, and crystal directions, but in this specification, due to format restrictions, instead of placing a bar above the number, a - (minus sign) may be placed before the number. Also, individual directions indicating directions within a crystal are expressed with [ ], collective directions indicating all equivalent directions are expressed with < >, individual planes indicating crystal planes are expressed with ( ), and collective planes with equivalent symmetry are expressed with {}. Also, trigonal crystals represented by the space group R-3m are generally expressed as a composite hexagonal lattice of hexagonal crystals for ease of understanding of the structure, and Miller indices may use not only (hkl) but also (hkil). Here, i is -(h+k).

[0027] (Embodiment 1) In this embodiment, an example of an analytical cell 10 of one embodiment of the present invention will be described with reference to FIGS.

[0028] <Analysis cell> Fig. 1(A) is a schematic perspective view of an analytical cell 10 according to one embodiment of the present invention. Fig. 1(B) is a schematic top view of the analytical cell 10. Fig. 2(A) is a schematic cross-sectional view taken along dashed line X1-X2 in Fig. 1(B). Fig. 2(B) is a schematic cross-sectional view taken along dashed line Y1-Y2 in Fig. 1(B).

[0029] 1(A), the analytical cell 10 has a first exterior body 11, a second exterior body 12, a third exterior body 13, and an X-ray transmissive window material 14. The analytical cell 10 allows X-rays to transmit from the outside to the inside of the analytical cell 10 through the X-ray transmissive window material 14.

[0030] As shown in FIG. 1(B), the first exterior body 11 has a first opening 21. One example of the shape of the first opening 21 is the shape shown by the dashed line in FIG. 1(B). The second exterior body 12 has a second opening 22 at a position overlapping with the first opening 21. One example of the shape of the second opening 22 is the shape shown by the dashed line in FIG. 1(B). In this way, the second opening 22 is smaller than the first opening 21 and is located inside the first opening 21.

[0031] As shown in Fig. 2(A) and Fig. 2(B), the second exterior body 12 is sandwiched between the first exterior body 11 and the third exterior body 13. The analytical cell 10 also has an O-ring 16, an insulating sheet 17, a laminate 30, a pedestal 15, and a spring 18. The X-ray transmissive window material 14 is larger than the second opening 22 and is bonded to the second exterior body 12 on the side of the space surrounded by the second exterior body 12 and the third exterior body 13. That is, in the space surrounded by the first exterior body 11, the second exterior body 12, the third exterior body 13, and the O-ring 16, the X-ray transmissive window material 14, the laminate 30, the pedestal 15, and the spring 18 are provided at positions overlapping the second opening 22. Moreover, the X-ray transmissive window material 14 is fixed to the surface of the second exterior body 12 facing the space so as to cover the entire second opening 22. Note that the insulating sheet 17 is preferably provided so that the first exterior body 11 and the third exterior body 13 do not come into direct contact with each other.

[0032] In order to seal the space surrounded by the second exterior body 12 and the third exterior body 13, the second exterior body 12 and the third exterior body 13 are preferably in contact with each other via an O-ring 16. In other words, the second exterior body 12 and the O-ring 16 are in contact with each other, and the O-ring 16 is in contact with the third exterior body 13, so that the inside of the analytical cell 10 is sealed by the second exterior body 12, the O-ring 16, and the third exterior body 13. The space surrounded by the second exterior body 12 and the third exterior body 13 may be referred to as the inside of the analytical cell 10. In other words, the inside of the analytical cell 10 is sealed, and the intrusion of atmospheric components such as water and oxygen from the outside to the inside of the analytical cell 10 is suppressed.

[0033] The second exterior body 12 is press-fitted into the inside of the first exterior body 11, and the first exterior body 11 and the third exterior body 13 are fixed together with insulating screws. For example, a high-strength resin material such as engineering plastic may be used as the material for the screws, and PEEK (polyether ether ketone) may be used. Although screw holes are omitted in Fig. 1 and the like, appropriate screw holes may be provided at positions where the first exterior body 11 and the third exterior body 13 can be fixed together.

[0034] Also, second exterior body 12 and third exterior body 13 may be in contact with each other via another O-ring in addition to O-ring 16. Note that the number of O-rings provided to seal the space surrounded by second exterior body 12 and third exterior body 13 is not limited to one, and may be two or more.

[0035] As shown in Figures 2(A) and 2(B), inside the analysis cell 10, the laminate 30 is sandwiched between the second exterior body 12 and the third exterior body 13. At this time, as shown in Figures 2(A) and 2(B), it is preferable that the upper surface of the laminate 30 is in close contact with the lower surface of the X-ray transmission window material 14 by the pedestal 15 and the spring 18. Note that the configuration for bringing the upper surface of the laminate 30 into close contact with the lower surface of the X-ray transmission window material 14 is not limited to the above example, and for example, a configuration in which the lower surface of the pedestal 15 is pushed up using a bolt penetrating the third exterior body 13 may be used. However, when the shape of the laminate 30 changes during charging and discharging, it is preferable to use a spring 18 that can press the laminate 30 with a constant force.

[0036] Details of the laminate 30 will be described with reference to Fig. 3(A) and Fig. 3(B). Fig. 3(A) is an enlarged schematic cross-sectional view of an area A enclosed by a dotted line in Fig. 2(A). Fig. 3(B) is a schematic cross-sectional view of a comparative example.

[0037] 3(A), the laminate 30 has a positive electrode 31, a separator 34, and a negative electrode 35. The positive electrode 31 has a positive electrode current collector 32 and a positive electrode active material layer 33.

[0038] Inside the analytical cell 10, the spring 18, the base 15, and the laminate 30 are configured by stacking the spring 18, the base 15, the positive electrode 31, the separator 34, and the negative electrode 35 in this order from the third exterior body 13 toward the second exterior body 12. The upper surface of the negative electrode 35 is in close contact with the lower surface of the X-ray transmission window material 14. As shown in FIG. 3(A), a part of the negative electrode 35 preferably has an area in contact with the second exterior body 12. Alternatively, a part of the negative electrode 35 is preferably electrically connected to the second exterior body 12. In this way, a part of the negative electrode 35 is electrically connected to the second exterior body 12, and the second exterior body 12 and the first exterior body 11 are electrically connected, so that the first exterior body 11 can be used as a negative electrode terminal of the analytical cell 10. Furthermore, since the positive electrode 31 is electrically connected to the third exterior body 13 via the spring 18 and the base 15, the third exterior body 13 can be used as a positive electrode terminal of the analytical cell 10.

[0039] More specifically, as an example of the region A, as shown in FIG. 3(A), a positive electrode collector 32 is provided on a base 15, a positive electrode active material layer 33 is provided on the positive electrode collector 32, a separator 34 is provided on the positive electrode active material layer 33, a negative electrode 35 is provided on the separator 34, an X-ray transmission window material 14 and a second exterior body 12 are provided on the negative electrode 35, and the second exterior body 12 is provided on the X-ray transmission window material 14. The X-ray transmission window material 14 may be connected to the second exterior body 12 via an adhesive 19. As the adhesive 19, a polyimide-based resin may be used, and it is preferable to prepare the adhesive 19 using a polyimide precursor solution that becomes a polyimide-based resin after curing. When a polyimide-based resin is used for the adhesive 19, since it has high resistance to dissolution in an electrolyte, the X-ray transmission window material 14 can be fixed for a long time. As the polyimide precursor solution, for example, a commonly known polyimide precursor solution such as Semicofine (registered trademark) manufactured by Toray can be used.

[0040] The positional relationship between the second exterior body 12, the X-ray transmission window material 14, the positive electrode 31, the negative electrode 35, and the pedestal 15 in the analytical cell 10 according to one embodiment of the present invention will be described with reference to FIG. 3(A). For the purpose of description, an arbitrary point inside the second opening 22 of the second exterior body 12, for example, the X-direction position CE of the center of the second opening 22, is defined. The X-direction distance from the position CE to the end of the second opening 22 is defined as L1, and the X-direction distance from the position CE to the end of the X-ray transmission window material 14 is defined as L2. The shortest X-direction distance among the X-direction distance from the position CE to the end of the positive electrode 31, the X-direction distance from the position CE to the end of the negative electrode 35, and the X-direction distance from the position CE to the end of the pedestal 15 is defined as L3.

[0041] At this time, it is preferable that L2 is longer than L1 in order to fix the X-ray transmissive window material 14. It is also preferable that L3 is longer than L1 in order to prevent deformation of the X-ray transmissive window material 14. If L3 is shorter than L1, there is a possibility that the X-ray transmissive window material 14 will deform, for example, as shown in the comparative example of FIG.

[0042] 3(A) and 3(B), the positional relationship in the X direction among the second exterior body 12, the X-ray transparent window material 14, the positive electrode 31, the negative electrode 35, and the base 15 has been described. Although not shown, the positional relationship in the Y direction among the X-ray transparent window material 14, the positive electrode 31, the negative electrode 35, and the base 15 is the same as the positional relationship in the X direction described above.

[0043] 4(A) to 4(F) are schematic top views of an example of components constituting the analysis cell 10. FIG. 4(A) is a schematic top view of the first exterior body 11, FIG. 4(B) is a schematic top view of the second exterior body 12, FIG. 4(C) is a schematic top view of the O-ring 16, FIG. 4(D) is a schematic top view of the pedestal 15, FIG. 4(E) is a schematic top view of the third exterior body 13, and FIG. 4(F) is a schematic top view of the insulating sheet 17. For the cross-sectional structures of each, refer to FIG. 2(A) and FIG. 2(B). The dashed lines in FIG. 4(A), FIG. 4(B), FIG. 4(D), and FIG. 4(E) indicate recesses or protrusions hidden from the top views, and the dotted lines in FIG. 4(A) to FIG. 4(E) are auxiliary lines showing the positional relationship of each component.

[0044] <XRD device> Using FIGS. 5 and 6, a configuration example of the XRD device 50 having the above-described analysis cell 10 will be described.

[0045] As shown in FIG. 5(A), the XRD device 50 includes an X-ray source 51, an X-ray detector 52, and a sample stage 53 that holds the analysis cell 10. Although not shown, the cable of the charge / discharge tester can be connected to the analysis cell 10. For example, the negative cable of the charge / discharge tester can be connected to the first exterior body 11, and the positive cable of the charge / discharge tester can be connected to the third exterior body 13. As for the connection of the cable, connection methods such as a connection method of providing a screw hole in the above-described exterior body and screwing, and a connection method of providing a terminal socket in the above-described exterior body and inserting a cable (pin) can be used.

[0046] As an outline of the XRD measurement, the incident X-ray X emitted from the X-ray source 51 in passes through the X-ray transmission window material 14 of the analysis cell 10, enters the inside of the analysis cell 10, and the reflected X-ray X reflected inside the analysis cell 10 refl passes through the X-ray transmission window material 14 and enters the X-ray detector 52, and the intensity of the reflected X-ray X refl is detected. In the XRD measurement, the measurement may be performed by a method such as repeatedly moving the X-ray source 51 and the X-ray detector 52 step by step in the directions indicated by the solid arrows in the figure and detecting the reflected X-ray X refl .

[0047] Not only a configuration using a zero-dimensional detector such as the X-ray detector 52 described in FIG. 5(A), but also a configuration using a one-dimensional detector such as the X-ray detector 54 shown in FIG. 5(B) may be used. The X-ray detector 54, which is a one-dimensional detector, reflects X at a plurality of angles as shown in FIG. 5(B). reflThe configuration using a one-dimensional detector or a two-dimensional detector is particularly preferable for in-situ XRD analysis because it can detect all at once and perform XRD measurement in a short time. Note that the results of measurement using a two-dimensional detector may be convoluted into one dimension and used.

[0048] Fig. 6(A) is a schematic diagram illustrating the positional relationship between an X-ray source 51, an analytical cell 10, and an X-ray detector 52 (or an X-ray detector 54) in an XRD device 50. Fig. 6(B) is a schematic top view illustrating the shape of a second opening 22 in the analytical cell 10.

[0049] As mentioned above, the incident X-rays in The incident X-rays X are transmitted through the X-ray transmitting window material 14 of the analytical cell 10 and enter the inside of the analytical cell 10. That is, the shape of the second opening 22 in the analytical cell 10 is in The irradiation area of ​​the incident X-rays must be larger than that of the in Even when the incidence angle of X-rays is low, in However, the shape of second opening 22 needs to be made large so as not to come into contact with the edge of second opening 22, that is, second exterior body 12.

[0050] However, when the shape of the second opening 22 is enlarged, the area of ​​the X-ray transmission window material 14 exposed to the outside of the analytical cell 10 increases. If the area of ​​the X-ray transmission window material 14 exposed to the outside of the analytical cell 10 increases, when gas is generated inside the analytical cell 10, the X-ray transmission window material 14 is more likely to be deformed by the gas.

[0051] Therefore, as the shape of the second opening 22 of the analytical cell 10, as shown in FIG. 6(A) and FIG. 6(B), it is preferable that the second opening 22 is a rectangle having a long side of width Wx in the direction connecting the X-ray source 51 and the X-ray detector 52 (or the X-ray detector 54) and a short side of width Wy shorter than width Wx in the direction perpendicular to the long side. By making it a rectangle, the amount of deformation of the X-ray transmission window material 14 can be suppressed. In addition, it is preferable that the rectangle is a rounded rectangle having corners with a radius of 1 / 2 the length of the short side. The outline of the rounded rectangle is composed of two parallel lines of equal length and two semicircles. The rectangle may be a rectangle with rounded corners. By making it into the above shape, even if gas is generated inside the analytical cell 10 and the internal pressure of the cell increases, the concentration of stress on the X-ray transmission window material 14 is alleviated, and the possibility of the film breaking and peeling off from the corners of the second opening 22 is reduced.

[0052] More specifically, in the XRD device 50, when the X-ray beam diameter is 2.0 mm, the size of the second opening 22 required to measure a range of 15 degrees or more is set to a width Wx of 6.0 mm or more and a width Wy of 2.2 mm or more (1.1 times the beam diameter or more), so that the incident X-rays Xin do not hit the second exterior body 12. In addition, as a configuration for suppressing deformation of the X-ray transmission window material 14, it is preferable that the width Wx is 10.0 mm or less and the width Wy is 5.0 mm or less. In other words, it is preferable that the width Wy is 2.2 mm or more and 5.0 mm or less, and the width Wx is 6.0 mm or more and 10.0 mm or less. As an example of a preferable configuration, for example, the width Wx can be 8.0 mm and the width Wy can be 4.0 mm.

[0053] 1 and other figures, the first exterior body 11 may have a recess. The first exterior body 11 preferably has a thin region. By providing the recess (thin region) in a region overlapping with a direction connecting the X-ray source 51 and the X-ray detector 52, the incident X-rays X can be prevented from being scattered even when the X-ray source 51 is positioned at a lower angle. in It is possible to configure the device so that it does not come into contact with first exterior body 11. EXAMPLES

[0054] In this example, an analytical cell according to one embodiment of the present invention was prepared, which does not have any metal material other than lithium metal in the X-ray irradiation path and reflection path, and in-situ XRD analysis was performed during a charge-discharge cycle in which charging at a high voltage of 4.5 V or more (4.70 V) and discharging were repeated.

[0055] The analytical cell 10 was fabricated with the second opening 22 having a width Wx of 8.0 mm and a width Wy of 4.0 mm in FIG. 6(B).

[0056] The first exterior body 11 shown in FIG. 4(A) was made of stainless steel (SUS316L). The second exterior body 12 shown in FIG. 4(B) was made of stainless steel (SUS316L). The base 15 shown in FIG. 4(C) was made of stainless steel (SUS316L). The third exterior body 13 shown in FIG. 4(D) was made of stainless steel (SUS316L). Stainless steel (SUS316L) has excellent oxidation-reduction resistance and high hardness, so it is suitable as a material for the above-mentioned exterior body. In addition, if the voltage applied to the analytical cell 10 is not high in the measurement, other types of stainless steel materials such as SUS316 and SUS403 may be used. In addition, the O-ring 16 shown in FIG. 2(A) was made of fluororubber (perfluoroelastomer), the insulating sheet 17 was made of fluororesin (polytetrafluoroethylene), and the spring 18 was made of stainless steel (SUS304).

[0057] The X-ray transparent window material 14 shown in Fig. 2(A) etc. was made of a 25 µm thick polyimide film. The X-ray transparent window material 14 was bonded to the second opening 22 of the second exterior body 12 using Semicofine (registered trademark) SP-811 manufactured by Toray. To harden the Semicofine, it was dried at 80°C for 20 minutes in a ventilated drying oven, and then heated at 320°C for 10 hours in a nitrogen (N2) atmosphere (N2 flow rate: 5 L / min) in a small muffle furnace.

[0058] FIG. 7(A) shows the first exterior body 11, second exterior body 12, third exterior body 13, base 15, O-ring 16, insulating sheet 17, spring 18, and screw (made of insulating PEEK).

[0059] Particles of lithium cobalt oxide having Mg, F, Ni, and Al on the surface layer, which has a stable crystal structure even when charged at a high voltage, were prepared as the positive electrode active material used in the positive electrode active material layer 33. The positive electrode active material particles were mixed with PVdF (polyvinylidene fluoride) as a binder, AB (acetylene black) as a conductive material, and NMP (N-methylpyrrolidone) as a dispersion medium to prepare a slurry. The slurry was applied onto an aluminum foil with a thickness of 20 μm and dried to prepare a positive electrode 31.

[0060] A 20 μm thick porous polypropylene film was prepared as a separator. A 0.6 mm thick lithium metal foil (lithium metal negative electrode) was prepared as the negative electrode 35. In addition, as the electrolyte, a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) in a ratio of EC:DEC=3:7 (volume ratio) was added with 2 wt% vinylene carbonate (VC) as an additive, and an electrolyte containing 1 mol / L lithium hexafluorophosphate (LiPF6) as a lithium salt was prepared.

[0061] The analytical cell 10 was fabricated by assembling the above-prepared components as shown in Fig. 2 etc. A top view photograph of the fabricated analytical cell 10 is shown in Fig. 7(B), a bottom view photograph is shown in Fig. 7(C), a side view photograph is shown in Fig. 7(D), and a perspective photograph is shown in Fig. 7(E).

[0062] The prepared analytical cell was placed in the XRD instrument. The measurement cable of the charge / discharge tester installed outside the XRD instrument was inserted into the XRD instrument and connected to the analytical cell. In this way, preparation for in-situ XRD analysis was completed.

[0063] While repeatedly charging and discharging the above analytical cell, in-situ XRD analysis was performed under the following XRD conditions. XRD equipment: Bruker AXS, D8 ADVANCE X-rays: Cu Kα1 Output: 40kV, 40mA Optical system: Goebel mirror (multilayer mirror) Goniometer radius: 280mm Detector distance: 230mm Detector: EIGER2 R 500K detector Scan method: θ=23°(fixed) Measurement range (2θ): 37 to 55° (2θ=46° centered ±9°) Counting time: 90 seconds / time

[0064] The conditions for charging and discharging were as follows: charging was performed at a constant current of 100 mAh / g per weight of the positive electrode active material up to 4.70 V, followed by constant voltage charging at 4.70 V until the charging current fell below 50 mAh / g. After a rest period, the battery was discharged at a constant current of 100 mAh / g down to 2.50 V. In this example, the above charging and discharging were repeated four times.

[0065] The results of the XRD measurement are shown in FIG. 8 and FIG.

[0066] 8(A) is a graph showing XRD patterns measured during repeated charge and discharge, including a rest period, a second charge period, a rest period, and a second discharge period. The vertical axis of the XRD pattern (intensity (au)) is a normalized value, and the horizontal axis is 2θ (°).

[0067] FIG. 8(B) is a graph showing the voltage of the analytical cell, and corresponds to FIG. 8(A). The vertical axis of FIG. 8(B) shows the number of XRD measurements, and the horizontal axis shows the voltage of the analytical cell (cell voltage (V)). For example, the voltage of the analytical cell at the time when the XRD pattern marked with X152 in FIG. 8(A) was measured is shown at the vertical position marked with X152 in FIG. 8(B). Similarly, the voltage of the analytical cell at the time when the XRD pattern marked with X311 in FIG. 8(A) was measured is shown at the vertical position marked with X311 in FIG. 8(B).

[0068] In Fig. 8(A), in addition to the XRD pattern measured using the analytical cell, the position of the (200) diffraction of aluminum (Al200: 44.72°) is shown. In addition, in the XRD pattern of lithium cobalt oxide measured in this example, the ranges of interest for material analysis are indicated with dotted lines as interest range A (43-46°) and interest range B (48-50°). These interest ranges were selected to confirm whether the crystal structure of lithium cobalt oxide changes continuously or discontinuously.

[0069] As shown in FIG. 8(A), the position of the (200) diffraction of aluminum is included within the range of interest A described above. However, the XRD pattern of this example, which was measured using the analytical cell of one embodiment of the present invention, was not affected by the (200) diffraction of aluminum, and the in-situ XRD analysis was possible.

[0070] 8(A) did not reveal any results suggesting deformation of the window material of the analytical cell, such as changes in background level, etc. In other words, the analytical cell of one embodiment of the present invention suppressed deformation of the window material of the analytical cell even under conditions where gas is likely to be generated in the cell, such as repeated charging at a high voltage of 4.70 V.

[0071] Figure 9 is a graph created from the measurement results shown in Figure 8, focusing on the change in the position of the diffraction peak in the focus range A and the focus range B. Figure 9(A) shows the change in the peak position, with the vertical axis representing the number of XRD measurements (times) and the horizontal axis representing the peak position (2θ), and Figure 9(B) shows the change in the voltage of the analytical cell corresponding to Figure 9(A).

[0072] It can be seen that the peak positions change continuously in both the focus range A (near 45°) and the focus range B (near 49°).

[0073] Here, the relationship between the change in the peak position and the change in the crystal structure will be described. In the case of normal lithium cobalt oxide without added elements, the crystal structure changes discontinuously from the O3 structure to the H1-3 structure during charging at a high voltage of 4.5V or more, and the peak positions of the attention range A and the attention range B change discontinuously at that time. On the other hand, as shown in FIG. 9, lithium cobalt oxide having Mg, F, Ni, and Al in the surface layer portion does not show a discontinuous change in the crystal structure of the positive electrode active material even when charged to a high voltage, and is a stable material in which the change in the crystal structure is suppressed. Thus, the characteristics of lithium cobalt oxide having Mg, F, Ni, and Al in the surface layer portion were confirmed in the in-situ XRD analysis of this embodiment.

[0074] As shown in the above examples, it was confirmed that the analytical cell of one embodiment of the present invention is an analytical cell that does not have any metal material other than lithium metal in the X-ray irradiation path and reflection path, and that suppresses deformation of the X-ray transmission window material due to gas generated in the analytical cell. In other words, the analytical cell of one embodiment of the present invention is capable of analyzing the crystal structure change of the positive electrode active material in in-situ XRD analysis during a charge-discharge cycle in which charging and discharging at a high voltage (4.70 V) of 4.5 V or more is repeated, without being affected by the (200) diffraction of aluminum. [Explanation of symbols]

[0075] 10 Analysis Cell 11 Exterior body 12 Exterior body 13 Exterior body 14 Window material for X-ray transmission 15 Pedestal 16 O-ring 17 Insulation sheet 18 Spring 19. Adhesive 21 Aperture 22 Aperture 30 Laminate 31 Positive electrode 32 Positive electrode current collector 33 Positive electrode active material layer 34 Separator 35 negative electrode 50 XRD equipment 51 X-ray source 52 X-ray detector 53 Sample stage 54 X-ray detector X in incident x-ray X refl reflected x-ray

Claims

1. An analytical cell having a first exterior body, a second exterior body, a third exterior body, an O-ring, an X-ray transmissive window material, a laminate, a base, and a spring, the X-ray transmissive window material has a resin film, the second exterior body sandwiched between the first exterior body and the third exterior body is in contact with the third exterior body via the O-ring; the first exterior body has a first opening, the second exterior body has a second opening having an area smaller than that of the first opening, the second opening is located inside the first opening, the X-ray transmissive window material, the laminate, the base, and the spring are provided at positions overlapping with the second opening in a space surrounded by the first exterior body, the second exterior body, the third exterior body, and the O-ring, the X-ray transmissive window material is fixed to a surface of the second exterior body facing the space so as to cover the entire second opening, the laminate is sandwiched between the X-ray transmissive window material and the base, the base is in contact with the third exterior body via the spring, the laminate includes, in order from the X-ray transmissive window material toward the base, a lithium metal negative electrode, a separator, and a positive electrode; The lithium metal negative electrode has an area in contact with the second exterior body.

2. In claim 1, The resin film comprises polyimide.

3. An X-ray diffraction apparatus comprising the analytical cell according to claim 1 or 2.

4. In claim 3, The X-ray diffraction apparatus includes an X-ray source and an X-ray detector. X-rays emitted from the X-ray source are reflected inside the analysis cell, The reflected X-rays are measured by the X-ray detector; An X-ray diffraction apparatus, wherein the shape of the second opening is a rectangle having a long side in a direction connecting the X-ray source and the X-ray detector.

5. In claim 4, The rectangle has a short side of 2.2 mm or more and 5.0 mm or less and a long side of 6.0 mm or more and 10.0 mm or less.

6. In claim 4, The rectangle has a short side of 2.2 mm or more and 5.0 mm or less and a long side of 6.0 mm or more and 10.0 mm or less, and is a rounded rectangle having corners with a radius equal to half the length of the short side.

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