阅读说明：本技术 电池材料的化学状态分析装置和方法 (Chemical state analysis device and method for battery material ) 是由 佐藤贤治 德田敏 和泉拓朗 米田哲弥 足立晋 于 2018-02-21 设计创作，主要内容包括：化学状态分析装置(10)具备：激发源(11),其向包含电池材料的试样(S)中的规定面内的照射区域(A)照射用于使该电池材料产生特征X射线的激发射线；分光晶体(13),其由面向照射区域(A)设置的平板构成；狭缝(12),其设置于照射区域(A)与分光晶体(13)之间,且与照射区域(A)及分光晶体(13)的规定的晶面平行；X射线线性传感器(15),其是在平行于该狭缝的方向上具有长度的线状的检测元件(151)以沿垂直于狭缝(12)的方向排列的方式设置而成的；波长谱制作部(161),其基于X射线线性传感器(15)检测出的特征X射线的强度来制作波长谱；峰值波长决定部(162),其求出峰值波长,该峰值波长是所述波长谱的峰值处的波长；以及化学状态确定部(163),其根据由峰值波长决定部(162)求出的峰值波长、以及标准曲线来求出用于确定试样(S)中的电池材料的化学状态的值,该标准曲线表示峰值波长与代表试样S中的电池材料的化学状态的值之间的关系。(A chemical state analysis device (10) is provided with: an excitation source (11) that irradiates an irradiation region (A) in a predetermined plane in a sample (S) containing a battery material with excitation radiation for causing the battery material to generate characteristic X-rays; a spectroscopic crystal (13) constituted by a flat plate disposed facing the irradiation region (A); a slit (12) which is provided between the irradiation region (A) and the spectroscopic crystal (13), and which is parallel to a predetermined crystal plane of the irradiation region (A) and the spectroscopic crystal (13); an X-ray linear sensor (15) in which linear detection elements (151) having a length in a direction parallel to the slit are arranged in a direction perpendicular to the slit (12); a wavelength spectrum creation unit (161) that creates a wavelength spectrum on the basis of the intensity of the characteristic X-rays detected by the X-ray linear sensor (15); a peak wavelength determination unit (162) that determines a peak wavelength that is a wavelength at the peak of the wavelength spectrum; and a chemical state determination unit (163) that determines a value for determining the chemical state of the battery material in the sample (S) on the basis of the peak wavelength determined by the peak wavelength determination unit (162) and a standard curve that represents the relationship between the peak wavelength and the value representing the chemical state of the battery material in the sample (S).)

1. A chemical state analysis device is characterized by comprising:

a) an excitation source that irradiates an irradiation region in a predetermined plane in a sample containing a battery material with excitation radiation for causing the battery material to generate characteristic X-rays;

b) a spectroscopic crystal constituted by a flat plate disposed facing the irradiation region;

c) a slit provided between the irradiation region and the spectroscopic crystal and parallel to a predetermined crystal plane of the irradiation region and the spectroscopic crystal;

d) an X-ray linear sensor in which linear detection elements having a length in a direction parallel to the slit are arranged in a direction perpendicular to the slit;

e) a wavelength spectrum creation unit that creates a wavelength spectrum based on the intensity of the characteristic X-ray detected by the X-ray linear sensor;

f) a peak wavelength determination unit that determines a peak wavelength that is a wavelength at a peak of the wavelength spectrum; and

g) and a chemical state determination unit that determines a value for determining a chemical state of the battery material in the sample, based on the peak wavelength determined by the peak wavelength determination unit and a standard curve that represents a relationship between the peak wavelength and a value representing the chemical state.

2. The chemical state analysis device according to claim 1,

the calibration curve is prepared based on the peak wavelength of the wavelength spectrum and the valence number of each of a plurality of calibration samples, which are chemically stable with respect to the chemical properties of the battery material to be measured and contain ions having different valence numbers and being composed of one of the elements contained in the battery material.

3. The chemical state analysis device according to claim 1,

the calibration curve is prepared based on the peak wavelength and the valence of a wavelength spectrum obtained from each of a plurality of calibration samples that are composed of the same kind of elements as the plurality of elements of the battery material to be measured and that contain ions that are composed of one of the plurality of elements and have different valences from each other.

4. The chemical state analysis device according to claim 1,

the calibration curve is prepared based on the peak wavelength of the wavelength spectrum when the same type of secondary battery is charged to the upper charge limit voltage and the peak wavelength of the wavelength spectrum when the same type of secondary battery is discharged to the discharge end voltage.

5. A chemical state analysis method characterized in that,

an irradiation region in a predetermined plane in a sample containing a cell material is irradiated with an excitation beam for causing the cell material to generate a characteristic X-ray,

splitting the characteristic X-ray by causing the characteristic X-ray generated in the irradiation region by irradiation with the excitation ray to pass through a slit and enter a spectroscopic crystal composed of a flat plate provided to face the irradiation region, the slit being provided between the irradiation region and the spectroscopic crystal in parallel with a predetermined crystal plane of the irradiation region and the spectroscopic crystal,

detecting the characteristic X-ray that has been split by the splitting crystal by an X-ray line sensor, wherein the X-ray line sensor is formed by arranging linear detecting elements having a length in a direction parallel to the slit in a direction perpendicular to the slit,

a wavelength spectrum is created based on the intensity of characteristic X-rays detected by the X-ray linear sensor, a peak wavelength which is the wavelength at the peak of the wavelength spectrum is determined, and a value for specifying the chemical state of the battery material in the sample is determined from the peak wavelength and a standard curve which represents the relationship between the peak wavelength and the value representing the chemical state.

6. The chemical state analysis method according to claim 5,

the calibration curve is prepared based on the peak wavelength of the wavelength spectrum and the valence number of each of a plurality of calibration samples, which are chemically stable with respect to the chemical properties of the battery material to be measured and contain ions having different valence numbers and being composed of one of the elements contained in the battery material.

7. The chemical state analysis method according to claim 5,

the calibration curve is prepared based on the peak wavelength and the valence of a wavelength spectrum obtained from each of a plurality of calibration samples that are composed of the same kind of elements as the plurality of elements of the battery material to be measured and that contain ions that are composed of one of the plurality of elements and have different valences from each other.

8. The chemical state analysis method according to claim 5,

the calibration curve is prepared based on the peak wavelength of the wavelength spectrum when the same type of secondary battery is charged to the upper charge limit voltage and the peak wavelength of the wavelength spectrum when the same type of secondary battery is discharged to the discharge end voltage.

Technical Field

The present invention relates to an apparatus and a method for analyzing a chemical state of a battery material, such as a valence number of ions of an element contained in a material (battery material) constituting a battery, before, during, or after use of a primary battery or a secondary battery.

Background

Secondary batteries such as lithium ion batteries are widely used as power sources for portable information terminals, electric vehicles, and the like, and it is required to improve charging capacity (which directly relates to the time during which a portable information terminal can be used by one charge and the distance over which an electric vehicle can travel), service life (which is generally expressed as the number of times charging and discharging can be repeated at a practical capacity), and the like. For this reason, development of materials used for electrodes for secondary batteries and the like has been vigorously carried out.

Non-patent document 1 describes the following: while the secondary battery is discharged after charging, XAFS (X-ray absorption fine structure) measurement is performed on the electrode of the secondary battery. XAFS assay is the following method: a spectrum of X-rays passing through or reflected by a sample is obtained by irradiating the sample with synchrotron radiation, and the electronic state of the sample is obtained from the position and shape of the peak of the X-rays absorbed by the sample. In non-patent document 1, the following measurement results are obtained: as the secondary battery is continuously discharged, the peak position of the obtained spectrum gradually shifts to the high energy side. This shift in peak position is caused by a change in the valence of ions of an element (Co ions in the example shown in non-patent document 1) contained in the material of the electrode during discharge of the secondary battery.

Disclosure of Invention

Problems to be solved by the invention

Since the measurement method described in non-patent document 1 uses synchrotron radiation, a large and expensive measurement device for carrying out the measurement method is required.

In the development of secondary batteries and the like, it is important to know the change in chemical state such as the valence of ions contained in the material of the electrode during discharge or charge, and for this purpose, it is required to measure and quantify the chemical state. Non-patent document 1 describes that it is considered that a change in the price can be quantitatively evaluated from the relationship between the SOC (State of Charge) of the secondary battery and the peak position. However, non-patent document 1 does not specifically show an evaluation method. Although the secondary battery is described here as an object, the same applies to the primary battery.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a battery material chemical state analysis device and method that can be made smaller and less expensive than conventional devices, and can quantify the chemical state of a battery material such as the valence of ions.

Means for solving the problems

In order to solve the above problems, a battery material chemical state analysis device according to the present invention includes:

a) an excitation source that irradiates an irradiation region in a predetermined plane in a sample containing a battery material with excitation radiation for causing the battery material to generate characteristic X-rays;

b) a spectroscopic crystal constituted by a flat plate disposed facing the irradiation region;

c) a slit provided between the irradiation region and the spectroscopic crystal and parallel to a predetermined crystal plane of the irradiation region and the spectroscopic crystal;

d) an X-ray linear sensor in which linear detection elements having a length in a direction parallel to the slit are arranged in a direction perpendicular to the slit;

e) a wavelength spectrum creation unit that creates a wavelength spectrum based on the intensity of the characteristic X-ray detected by the X-ray linear sensor;

f) a peak wavelength determination unit that determines a peak wavelength that is a wavelength at a peak of the wavelength spectrum; and

g) and a chemical state determination unit that determines a value for determining a chemical state of the battery material in the sample, based on the peak wavelength determined by the peak wavelength determination unit and a standard curve (calibration curve) that represents a relationship between the peak wavelength and the value representing the chemical state.

The method for analyzing the chemical state of a battery material according to the present invention, which has been accomplished to solve the above problems, is characterized in that,

an irradiation region in a predetermined plane in a sample containing a cell material is irradiated with an excitation beam for causing the cell material to generate a characteristic X-ray,

splitting the characteristic X-ray by causing the characteristic X-ray generated in the irradiation region by irradiation with the excitation ray to pass through a slit and enter a spectroscopic crystal composed of a flat plate provided to face the irradiation region, the slit being provided between the irradiation region and the spectroscopic crystal in parallel with a predetermined crystal plane of the irradiation region and the spectroscopic crystal,

detecting the characteristic X-ray that has been split by the splitting crystal by an X-ray line sensor, wherein the X-ray line sensor is formed by arranging linear detecting elements having a length in a direction parallel to the slit in a direction perpendicular to the slit,

a wavelength spectrum is created based on the intensity of characteristic X-rays detected by the X-ray linear sensor, a peak wavelength which is the wavelength at the peak of the wavelength spectrum is determined, and a value for specifying the chemical state of the battery material in the sample is determined from the peak wavelength and a standard curve which represents the relationship between the peak wavelength and the value representing the chemical state.

In the present invention, the term "wavelength spectrum" also includes an energy spectrum and a wave number spectrum represented by energy and wave number which are values corresponding to the wavelength. Similarly, the term "peak wavelength" includes peak energy and peak wave number.

In the present invention, the following X-ray spectroscopic analysis apparatus is used: the X-ray spectroscopic analyzer includes the excitation source, the spectroscopic crystal, the slit, and the X-ray linear sensor having the above-described configuration. This X-ray spectroscopic analyzer is invented by the present inventors and is described in patent document 1. In this X-ray spectroscopic analyzer, the excitation radiation is irradiated to the irradiation region to emit characteristic X-rays from each position in the irradiation region in each direction, but only the characteristic X-rays passing through the slit among the characteristic X-rays reach the spectroscopic crystal. When the irradiation region is divided into linear portions parallel to the slit, only the characteristic X-rays emitted from any one of the linear portions among the characteristic X-rays having a specific wavelength (energy) pass through the slit, are incident and diffracted at an incident angle satisfying a diffraction condition, and are detected by a specific one of the detection elements of the X-ray linear sensor. Therefore, since each detection element detects a different characteristic X-ray of a specific wavelength, the wavelength spectrum of the characteristic X-ray can be obtained from the intensity of each detection element. Here, regarding the characteristic X-rays having different wavelengths, only the characteristic X-rays emitted from the linear portions having different wavelengths are detected by the X-ray linear sensor, but since the average value in the linear portion is obtained from one linear portion, even if the composition in the irradiation region is somewhat uneven, the measurement can be performed without any problem.

The wavelength (peak wavelength) at the peak of the wavelength spectrum obtained by using the X-ray spectroscopic analysis device as described above is a value that differs depending on the type of the element contained in the battery material, and even if the same element is used, if the chemical state of the battery material such as the valence of the ion differs, the wavelength (peak wavelength) at the peak is a slightly different value. Therefore, by applying the measured value of the peak wavelength to a calibration curve showing the relationship between the peak wavelength and the value representing the chemical state of the battery material, it is possible to obtain a value representing the chemical state of the battery material in the sample as the measurement target.

According to the present invention, as the excitation source, an X-ray source, an electron beam source, or the like used as a light source for irradiating a sample with characteristic X-rays generated from the sample in a general X-ray spectroscopic analyzer can be used as it is. Therefore, the chemical state analysis device for a battery material according to the present invention can be smaller and cheaper than conventional devices, and the chemical state analysis method for a battery material according to the present invention can be implemented by such cheap devices.

In addition, according to the present invention, the chemical state of the battery material represented by the valence of the ion or the like can be quantified by using the calibration curve.

In the chemical state analysis device and method for a battery material according to the present invention, it is preferable that the standard curve is prepared based on the peak wavelength of the wavelength spectrum and the valence number obtained from each of a plurality of standard samples having chemical properties more stable than the chemical properties of the battery material to be measured and containing ions having one of the elements included in the battery material and different valence numbers from each other. In this case, the value representing the chemical state of the battery material is the valence number of ions that the battery material has. Since the battery material itself may have a change in valence due to charge and discharge, chemical reaction, or the like, the accuracy of the calibration curve can be improved by using a calibration sample having a chemical property more stable than that of the battery material. As such a chemically stable standard sample, for example, an oxide, a hydroxide, a sulfide, a chloride, or the like of an element to be subjected to valence determination in a battery material can be used.

Alternatively, in the apparatus and method for analyzing a chemical state of a battery material according to the present invention, the standard curve may be created based on a peak wavelength of a wavelength spectrum and a valence number of each of a plurality of standard samples that are composed of the same kind of elements as a plurality of elements included in the battery material to be measured and that contain ions composed of one of the plurality of elements and having different valence numbers. In this case, the value representing the chemical state of the battery material is the valence number of the ion contained in the battery material. In this way, by using a standard sample composed of the same kind of element as the battery material to be measured, the standard curve is prepared with a composition close to that of the battery material actually used, and therefore the accuracy of the standard curve can be improved.

In the chemical state analysis device and method for a battery material according to the present invention, the standard curve may be determined with reference to a peak wavelength of a wavelength spectrum when charging to a charge upper limit voltage and a peak wavelength of a wavelength spectrum when discharging to a discharge end voltage in a secondary battery of the same type. In this case, the price of the battery material is not required. For example, in a secondary battery as a standard sample, a peak wavelength of a wavelength spectrum when the secondary battery is charged to a charge upper limit voltage is defined as 100%, a peak wavelength when the secondary battery is discharged to a discharge end voltage is defined as 0%, a line connecting the peak wavelength and the discharge end voltage with a straight line is defined as a standard curve showing a relationship between the peak wavelength and a value representing a chemical state of a battery material in the sample, and a value representing the chemical state of the sample can be obtained by applying a peak wavelength obtained when the sample to be measured is measured to the standard curve.

ADVANTAGEOUS EFFECTS OF INVENTION

The chemical state analysis device and method for a battery material according to the present invention can be made smaller and cheaper than conventional devices, and can quantify the chemical state of a battery material by the valence of ions or the like.

Drawings

Fig. 1 is a schematic side view showing one embodiment of a chemical state analyzer according to the present invention.

Fig. 2 is a diagram (a) showing an example of a lithium ion battery to be measured, and a diagram (b) showing a state in which the lithium ion battery is disassembled and attached to a sample holder for measurement.

Fig. 3 is a perspective view showing the arrangement of the slit, the spectroscopic crystal, the X-ray linear sensor, and the sample holder in the chemical state analyzer of the present embodiment.

FIG. 4 shows Mn to stabilize chemical properties₂O₃And MnO₂The results of the standard curve prepared as a standard sample and the analysis of the valence number of Mn contained in the battery material of the sample using the standard curve are (a) a graph showing the standard curve and the analysis result at the time of charge, and (b) a graph showing the standard curve and the analysis result at the time of discharge.

FIG. 5 shows LiMn to be a sample to be analyzed having a plurality of elements of the same kind as the battery material₂O₄And Li₂MnO₃The results of the standard curve prepared as a standard sample and the analysis of the valence number of Mn contained in the battery material of the sample using the standard curve are (a) a graph showing the standard curve and the analysis result at the time of charge, and (b) a graph showing the standard curve and the analysis result at the time of discharge.

FIG. 6 (a) is a graph showing the results of a calibration curve prepared by using as a standard sample the battery material of a secondary battery subjected to primary charging to a charging upper limit voltage and a secondary battery subjected to primary discharging to a discharging end voltage after that, and an analysis of the chemical state of the secondary battery during charging or discharging using the calibration curve, and (b) of fig. 6 is a graph showing the results of a calibration curve created using, as a calibration sample, the battery material of a secondary battery after a primary charge in which charging to the upper charge limit voltage is performed and a primary discharge in which discharging to the end discharge voltage is performed, and then a secondary battery after a secondary charge in which charging to the upper charge limit voltage is performed and a secondary discharge in which discharging to the end discharge voltage is performed, and analyzing the chemical state of the secondary battery during charging or discharging using the calibration curve.

Detailed Description

Embodiments of an apparatus and a method for analyzing a chemical state of a battery material according to the present invention will be described with reference to fig. 1 to 6.

(1) The chemical state analyzer of the present embodiment has a structure

Fig. 1 is a schematic side view of a chemical state analyzer 10 according to the present embodiment. The chemical state analyzer 10 includes an excitation source 11, a slit 12, a spectroscopic crystal 13 made of a flat plate, an X-ray linear sensor 14, a sample holder 15, a data processing unit 16, and a calibration curve data storage unit 17.

The excitation source 11 is an X-ray source that irradiates X-rays as excitation light (excitation rays) onto a predetermined surface of a battery material of a battery, which is the sample S held by the sample holder 15. Instead of an X-ray source, an electron-ray source may also be used. Hereinafter, a region of the battery material to which the excitation light is irradiated on the predetermined surface is referred to as an "irradiation region a". In the present embodiment, the irradiation region a is irradiated with the excitation light vertically, but the irradiation region a may be irradiated with the excitation light at an oblique angle.

The slit 12 is disposed between the irradiation region a and the spectroscopic crystal 13. In the present embodiment, the spectroscopic crystal 13 is a spectroscopic crystal having a predetermined crystal plane parallel to the crystal surface. The slit 12 is arranged parallel to the irradiation region a and a crystal plane of the spectroscopic crystal 13 (in the present embodiment, the surface of the spectroscopic crystal 13) for detecting the characteristic X-ray (in fig. 1, perpendicular to the plane of the paper).

The X-ray line sensor 14 is provided with a plurality of linear detection elements 141 having a length in a direction parallel to the slit 12 (perpendicular to the paper surface of fig. 1) and arranged in a direction perpendicular to the slit 12. As described above, the characteristic X-ray having a specific wavelength (energy) is detected by a specific one of the detection elements 141 of the X-ray linear sensor 14, and each detection element 141 detects a different characteristic X-ray of a specific wavelength. Therefore, each detection element 141 only needs to detect the intensity (photon count) of the X-ray incident on the detection element 141, and a function of strictly detecting the wavelength and energy of the incident X-ray is not required.

The data processing unit 16 is realized by hardware such as a personal computer or software, and includes a wavelength spectrum creation unit 161, a peak wavelength determination unit 162, and a chemical state determination unit 163 as functional blocks.

The wavelength spectrum creation unit 161 creates a wavelength spectrum from the wavelength of the characteristic X-ray detected by each detection element 141 of the X-ray line sensor 14 and the detection intensity of each detection element 141.

The peak wavelength determining unit 162 detects a peak from the wavelength spectrum generated by the wavelength spectrum generating unit 161, and obtains a value of the peak wavelength. A known method used for general data processing can be applied to the detection of the peak.

The chemical state specifying unit 163 specifies the chemical state of the battery material in the sample S based on the peak wavelength obtained by the peak wavelength determining unit 162 and the standard curve stored in the standard curve data storage unit 17 described below.

The calibration curve data storage unit 17 stores data of a calibration curve that is created in advance and indicates a relationship between a peak wavelength of a wavelength spectrum of the characteristic X-ray and a chemical state. The standard curve was made by: the chemical state analyzer 10 of the present embodiment, or another characteristic X-ray measuring device, is used to determine the relationship between the peak wavelength of the wavelength spectrum of the characteristic X-ray emitted from the standard sample and the value of the index representing the chemical state of the standard sample, such as the valence of the element contained in the standard sample.

For example, as the standard sample, a plurality of samples as follows can be used: the chemical property ratios of the plurality of samples are such that the chemical properties of the battery material in the battery to be actually measured are higher than the chemical properties of the battery materialThe plurality of samples are stable and contain ions which are composed of one of the elements of the battery material and have different valences from each other. As a specific example, LiMn, which is one of the materials of electrodes used in lithium ion batteries₂O₄In the case of a battery material to be measured, LiMn₂O₄Mn itself has a valence of +3.5, while MnO₂Mn of (2) has a valence of +4, Mn₂O₃Mn of (2) has a valence of an integer of +3, MnO₂And Mn₂O₃Chemical property ratio of (2) LiMn₂O₄The chemical properties of (A) are more stable. Thus, MnO is used₂And Mn₂O₃The peak wavelengths of K β 1,3 rays, which are one of the characteristic X rays of Mn, were obtained as standard samples for the two standard samples, and two points, which are the measurement results of the two standard samples, were plotted on a graph in which one of the vertical and horizontal axes is a valence and the other is a peak wavelength, and a straight line connecting the two points was set as a standard curve.

In addition, as the standard sample, a plurality of samples as follows may be used: the plurality of samples are composed of a plurality of elements of the same kind as the battery material in the battery to be actually measured, and the plurality of samples contain ions composed of one of the plurality of elements and having different valences from each other. As a specific example, the above LiMn is₂O₄In the case of a battery material to be measured, LiMn having a valence of +3.5 for Mn₂O₄By itself and Li having a valence of +4 for Mn₂MnO₃The two standard samples each measure the peak wavelength of K β 1, 3-ray, which is one of the characteristic X-rays of Mn, and two points, which are the measurement results of the two standard samples, are plotted on a graph in which one of the vertical axis and the horizontal axis is a valence and the other is a peak wavelength, and a straight line connecting the two points is a standard curve.

Alternatively, a secondary battery charged to the upper limit charge voltage of the same type as the battery to be actually measured and a secondary battery discharged to the end-of-discharge voltage of the same type as the battery to be actually measured may be prepared, and the peak wavelengths of the characteristic X-rays emitted from the battery material may be measured for each of the two secondary batteries as data for creating the calibration curve. In this case, a point where the peak wavelength at the time of charging to the charging upper limit voltage is set to the index 100% and a point where the peak wavelength at the time of discharging to the discharge end voltage is set to the index 0% are plotted on a graph in which one of the vertical axis and the horizontal axis is set to the index of the chemical state represented by a numerical value of 0% to 100% and the other is set to the peak wavelength, and a straight line connecting the two points is set as a standard curve. The valence of the element contained in the battery material is not considered when using the standard curve.

In the example described above, two standard samples are used, but three or more standard samples may be used, and a straight line or a curve connecting three or more obtained data points, or a straight line determined so that an error between the straight line and the three or more data points is minimized, or a curve represented by a quadratic or higher function may be used as the standard curve.

(2) Operation of the chemical state analysis device of the present embodiment and the chemical state analysis method of the present embodiment

Next, the operation of the chemical state analysis device 10 of the present embodiment and the chemical state analysis method of the present embodiment will be described.

First, the sample S is set on the sample holder 15. Here, a case will be described, as an example, in which the positive electrode material 21 of the lithium ion battery 20 shown in fig. 2 (a) is used as a battery material to be measured. In the lithium ion battery 20, LiMn is used at the time of the discharge end voltage₂O₄A separator 23 is provided between the positive electrode material 21 and the negative electrode material 22 made of Li, and a current collector 24 made of Al is provided on the opposite side of the separator 23 from the positive electrode material 21. The positive electrode material 21, the negative electrode material 22, the separator 23, and the current collector 24 are covered with a laminate 26, and the inside of the laminate 26 is filled with an electrolyte 25 in addition to the above-described components. The lithium ion battery 20 can be measured even in the form of being left as it is, but this is doneIn the case of this, the excitation light irradiated to the positive electrode material 21 and the characteristic X-ray emitted from the positive electrode material 21 pass through either the separator 23 or the current collector 24, and the intensity of the detected characteristic X-ray is reduced. Therefore, in the present embodiment, after the lithium ion battery 20 is disassembled and the negative electrode material 22, the separator 23, and the electrolyte 25 are removed, the positive electrode material 21 is set on the sample holder 15 so as to face the excitation source 11 ((b) of fig. 2). However, since it is difficult to separate the current collector 24 from the positive electrode material 21, the current collector 24 is disposed on the opposite side of the excitation source 11 from the positive electrode material 21 in a state where the current collector 24 remains. As shown in fig. 2 b, the periphery of the positive electrode material 21 (and the current collector 24) may be covered with a new laminate material 27 (different from the laminate material 26 provided in the lithium ion battery 20) to protect the positive electrode material 21. The laminate 27 is a constituent material mainly made of resin such as nylon or polypropylene, and has a very low action of attenuating excitation light and characteristic X-rays as compared with the separator 23 and the collector 24, and therefore does not hinder the measurement.

Next, X-rays as excitation light are irradiated from the excitation source 11 to the irradiation region a. Thereby, characteristic X-rays having energies different depending on the elements constituting the electrode material (in the example of fig. 2, the positive electrode material 21) are emitted from the entire irradiation region a in various directions from various positions within the irradiation region a. Regarding these characteristic X-rays, when the irradiation region a is divided into linear portions parallel to the slit 12 (see fig. 1, a1, a2 · · · · · fig. 3, here, fig. 3 shows the arrangement of the slit 12, the spectroscopic crystal 13, the X-ray line sensor 14, and the sample holder 15 in a perspective view), only the characteristic X-rays emitted in a direction incident on the surface of the spectroscopic crystal 13 at a specific one incident angle (90- θ) ° (θ ° is a diffraction angle in the case where the characteristic X-rays are bragg-reflected by the spectroscopic crystal 13) pass through the slit 12. Further, the linear portions at different positions have different incident angles of the characteristic X-rays incident on the spectroscopic crystal 13 after passing through the slit 12. For example, the characteristic X-ray emitted from the linear portion A1 is at only one incident angle (90-theta)₁) DEG (diffraction angle theta)₁Degree) of the X-ray beam is incident on the spectroscopic crystal 13, and the characteristic X-ray beam emitted from the other linear portion a2 is emitted only in the same manner as the above-mentioned characteristic X-ray beamIncident angle (90-theta)₁) An angle of incidence (90-theta) different₂) DEG (diffraction angle theta)₂Degree) is incident on the spectroscopic crystal 13.

The characteristic X-rays incident on the spectroscopic crystal 13 from each linear portion of the irradiation region a are diffracted (reflected) at the diffraction angle θ only when they have a wavelength satisfying the condition of bragg reflection, that is, λ ═ 2d/n sin θ (λ is the wavelength of the characteristic X-rays, d is the interplanar spacing of the spectroscopic crystal 13, and n is the order). The characteristic X-ray diffracted (reflected) by the spectroscopic crystal 13 is detected by one detection element 141 of the detection elements 141 of the X-ray linear sensor 14. Since the light is incident on the spectroscopic crystal 13 at a specific one of the incident angles (90- θ) °, which differs according to the linear portion within the irradiation region a, as described above, only characteristic X-rays of a specific one of the wavelengths, which differs, are incident on the X-ray line sensor 14 in each linear portion, and are detected by the different detection elements 141. For example, among the characteristic X-rays emitted from the linear portion a1, only the characteristic X-rays having the wavelength λ₁＝(2d/n)sinθ₁Is incident on the X-ray line sensor 14 and is detected by one detection element 1411, and only the characteristic X-rays emitted from the linear portion a2 have the X-ray intensity λ₁Different wavelength lambda₂＝(2d/n)sinθ₂The characteristic X-ray of (1) is incident on the X-ray line sensor 14 and detected by a detection element 1412 different from the detection element 1411 (refer to fig. 1 and 3).

Therefore, the wavelength spectrum creating unit 161 acquires a signal of the intensity (photon count) of the X-ray detected by each detector 141 within a predetermined measurement time from the X-ray line sensor 14, and then creates a wavelength spectrum of the characteristic X-ray emitted from the irradiation field a based on the detected intensity and the detected wavelength. Here, the measurement time may be appropriately determined according to the intensity of the characteristic X-ray per unit time that reaches the X-ray line sensor 14, but the measurement time can be shortened by disassembling the lithium ion battery 20 as described above and irradiating the positive electrode material 21 with excitation light without passing through the separator 23 and the current collector 24.

Next, the peak wavelength determination unit 162 detects a peak from the wavelength spectrum generated by the wavelength spectrum generation unit 161, and determines a peak wavelength.

Next, the chemical state specifying unit 163 selects a calibration curve for the element based on the element included in the battery material to be measured, which is input from an input unit (not shown) by the measurer in advance. Alternatively, the measurer may select the standard curve itself using the input unit. Next, the chemical state determination unit 163 obtains an index representing the chemical state, such as the valence number corresponding to the peak wavelength obtained by the peak wavelength determination unit 162, from the selected calibration curve. By the above operation, the one chemical state analysis operation is ended.

(3) The standard curve thus prepared and the result of analysis of the sample

Next, a standard curve actually prepared in the chemical state analysis apparatus and method according to the present embodiment and results obtained by analyzing a sample using the standard curve are shown.

(3-1) Standard Curve created Using Stable Standard sample and analysis results

In the graphs of (a) and (b) of fig. 4, Mn based on stabilization of chemical properties is shown by a straight line₂O₃(Mn is +3 valent) and MnO₂(Mn +4 + valence) as a standard sample, and a standard curve showing the relationship between the valence of Mn and the peak energy (corresponding to the peak wavelength) was prepared. The abscissa of the graph represents the valence of Mn, and the ordinate represents the peak energy. In addition, the two standard curves shown in (a) and (b) of fig. 4 are the same. In the figure, two white circle symbols represent measured values of peak energy, and a straight line is a standard curve defined by connecting measured points of the two white circle symbols with a straight line. For Mn₂O₃、MnO₂Each measurement was performed 5 times, and the average of the peak energy was obtained. In addition, the value of the standard deviation is set as an error bar (error bar).

In fig. 4 (a), the values of peak energy obtained by measuring the following states by the chemical state analysis device and method according to the present embodiment are shown by black circles on the standard curve at the same time as the standard curve: to useFrom LiMn₂O₄A state before the lithium ion battery 20 constituting the positive electrode material 21 is charged for the second time after being charged and discharged for the first time as aging (referred to as "SOC-0". hereinafter, "SOC" is a "state of charge" (abbreviation for States of charge)); the charging was performed to a state of 50% capacity (SOC-50); and the charging is performed to a state of 100% capacity (SOC-100). In fig. 4 (b), the values of the peak energy obtained by measuring the following states by the chemical state analysis device and method according to the present embodiment are shown by black circles on the standard curve at the same time as the standard curve: a state in which the secondary charging is performed to 100% after the primary charging and discharging is performed as aging (the same as the above-described "SOC-100") using the same lithium ion battery 20; after that, the Discharge was performed to 50% (to "DOD-50". The "DOD" is abbreviated as "Depth of Discharge"); and a state (DOD-100) in which the discharge was performed to 100% (to the capacity 0%). These data were also measured 5 times in each charge/discharge stage as in the case of the standard sample, and the average of the peak energy was obtained, and the value of the standard deviation was set as an error bar. The values on the horizontal axis at the data points indicated by the black circles indicate the valence (chemical state) of Mn in the positive electrode material 21 in each charged or discharged state.

(3-2) Standard Curve created Using Standard sample having multiple elements of the same kind as the Battery Material to be analyzed, and analysis result

In the graphs of (a) and (b) of fig. 5, LiMn based on the material to be the same as that of the cathode material 21 is shown by a straight line₂O₄And Li composed of a plurality of elements (Li, Mn, and O) of the same kind as that of the positive electrode material 21₂MnO₃A calibration curve showing the relationship between the valence of Mn and the peak energy (corresponding to the peak wavelength) was prepared as a result of measurement using a standard sample. Similarly to fig. 4, the abscissa of the graph represents the valence of Mn, and the ordinate represents the peak energy, and the two standard curves shown in (a) and (b) are the same. Two white circles in the figureThe symbol represents a measured value of peak energy, and the straight line is a standard curve defined by connecting the measured points of two white circle symbols with a straight line. For LiMn₂O₄、Li₂MnO₃Each measurement was performed 5 times, and the average of the peak energy was obtained, and the value of the standard deviation was defined as an error bar.

In fig. 5 (a), in parallel with the standard curve, the values of the peak energy obtained by measuring the lithium ion batteries 20 in the SOC-0, SOC-50, and SOC-100 states of charge by the chemical state analysis device and method according to the present embodiment are shown by the black circle symbols on the standard curve in the same manner as the example shown in fig. 4 (a). In addition, in fig. 5 (b), in parallel with the standard curve, the values of the peak energy obtained by measuring the lithium ion battery 20 in the state of charge of SOC-100 and the state of discharge of DOD-50 and DOD-100 by the chemical state analysis device and method according to the present embodiment are shown by the black circle symbols on the standard curve as in the example shown in fig. 4 (b). These data were also measured 5 times in each charge/discharge stage as in the case of the standard sample, and the average of the peak energy was obtained, and the value of the standard deviation was set as an error bar.

In addition, the error bars of the data of the standard sample and the sample to be analyzed shown so far can be made smaller by increasing the measurement time or the number of times of measurement.

(3-3) calibration curves prepared by using, as calibration samples, cell materials of a secondary battery charged to the upper limit charge voltage and a secondary battery discharged to the end-of-discharge voltage, and analysis results

In the graph of fig. 6 a, a calibration curve is shown by straight lines, which is prepared by using, as calibration samples, the positive electrode material 21 of the lithium ion battery 20 that has been charged to the upper charge limit voltage (SOC-100 (initial charge)) and the positive electrode material 21 of the lithium ion battery 20 that has been charged to the upper charge limit voltage and then discharged to the end-of-discharge voltage (DOD-100 (initial discharge)). In this standard curve, the chemical state of SOC-100 (first charge) is defined as 100%, the chemical state of DOD-100 (first discharge) is defined as 0%, the indices of these chemical states are plotted on a graph with the abscissa and the value of the peak energy as the ordinate (white circle symbols in fig. 6 (a)), and both are connected by a straight line. Fig. 6 (a) shows, on a standard curve, the values of peak energy measured by the chemical state analysis device and method of the present embodiment for the following states, simultaneously with a black circle symbol: a state (SOC-50) in which the lithium ion battery 20 is charged to 50% of capacity after being charged once to the upper limit charge voltage and discharged once to the end discharge voltage; and a state of being discharged to 50% of capacity (DOD-50) after the second charge to the charge upper limit voltage. The value on the horizontal axis at the data points of these black circle symbols is an index representing the chemical state of the positive electrode material 21 in each charged or discharged state. Further, for both standard samples, measurements were performed 5 times each at SOC-50 and DOD-50, and the average of the peak energy was obtained, and the value of the standard deviation was defined as an error bar.

In the graph of fig. 6 (b), a calibration curve is shown by a straight line, which is created by the same method as that of fig. 6 (a) using, as a calibration sample, the positive electrode material 21 of the lithium ion battery 20 that has been subjected to the first charge to the charge upper limit voltage and the first discharge to the discharge end voltage and then the second charge to the charge upper limit voltage, and the positive electrode material 21 of the lithium ion battery 20 that has been subjected to the second discharge to the discharge end voltage. The data (black circles in the figure) of SOC-50 and DOD-50 are data obtained by plotting the peak energy values measured by the chemical state analysis apparatus and method according to the present embodiment on a calibration curve. The value on the horizontal axis at the data points of these black circle symbols is an index representing the chemical state of the positive electrode material 21 in each charged or discharged state. Further, for both standard samples, measurements were performed 5 times each at SOC-50 and DOD-50, and the average of the peak energy was obtained, and the value of the standard deviation was defined as an error bar.

As described above, by creating standard curves indicating the relationship between the peak wavelength and the value representing the chemical state of the battery material using various standard samples, and plotting the peak energy value measured with the battery material to be analyzed on these standard curves, the chemical state of the battery material to be analyzed, such as the valence number of the element, can be quantitatively determined.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. For example, in the present embodiment, the measurement is performed after disassembling the battery (lithium ion battery 20) to be measured and only the battery material (for example, positive electrode material 21) is rearranged, but the disassembly of the battery may be omitted when the measurement accuracy may be slightly low or when the time for detecting the characteristic X-ray is allowed to be extended. The measurement target is not limited to the positive electrode material, and may be a substance contained in the negative electrode material as long as the valence number changes. The battery to be measured is not limited to the lithium ion battery, and various primary batteries and secondary batteries can be used as the measurement target.

Description of the reference numerals

10: a chemical state analyzing device; 11: an excitation source; 12: a slit; 13: a spectroscopic crystal; 14: an X-ray linear sensor; 141. 1411, 1412: a detection element; 15: a sample holder; 16: a data processing unit; 161: a wavelength spectrum creation unit; 162: a peak wavelength determination unit; 163: a chemical state determination section; 17: a standard curve data storage unit; 20: a lithium ion battery; 21: a positive electrode material; 22: a negative electrode material; 23: a diaphragm; 24: a current collector; 25: an electrolyte; 26. 27: a laminate material; a: irradiating the area; s: and (4) sampling.