Inspection method and inspection device of negative electrode carbon material of lithium ion battery

Abstract

To provide an inspection method of a negative electrode carbon material of a lithium ion battery, of which an inspection accuracy is improved, and provide an inspection device for executing the inspection method.SOLUTION: An inspection method of a negative electrode carbon material of a lithium ion battery, includes: a step of manufacturing the negative electrode carbon material of the lithium ion battery; a step of measuring a BET ratio surface area S of the negative electrode carbon material; a step of calculating an abundance ratio rn (herein below n is a suffix expressing a chemical coupling state or a type of a functional group) in each of a chemical coupling state or a functional group (n) of a hetero atom existed on a front surface by performing an analysis of the chemical coupling state of a front surface of the negative electrode carbon material with an X-ray photoelectron spectroscopy; a step of calculating an activation energy Ean in a desolvation reaction model of Li+ in each of the chemical coupling state or the functional group (n); a step of calculating a Boltzmann factor FBn from the activation energy Ean; and a step of determining a quality of the negative electrode carbon material by comparing a determination value as a sum of a volume of the S and the rn and a volume of the FBn with a threshold value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method and an apparatus for inspecting a negative electrode carbon material of a lithium ion battery. [Background technology]

[0002] Lithium-ion batteries are widely used in portable devices such as personal computers and smartphones, as well as in batteries for environmentally friendly vehicles.

[0003] In recent years, lithium ion batteries have been required to have higher performance, such as faster charging and discharging. To meet this demand, heteroatom-doped carbon materials have been investigated as new negative electrode carbon materials for lithium ion batteries.

[0004] Patent Document 1 discloses a carbon material doped with nitrogen elements so as to substitute for a portion of the carbon elements in the carbon skeleton, characterized in that the ratio of nitrogen elements to carbon elements in the carbon material (N / C) is 0.01 to 20 mol %, and the ratio of N3 type nitrogen atoms to total nitrogen on the surface of the carbon material (surface N3), as measured by X-ray photoelectron spectroscopy (XPS), is 10 mol % or more. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-089016 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when heteroatom-doped negative electrode materials were produced, there had been no examples of quantitatively evaluating the contribution to battery performance of each possible chemical bond state or functional group of the heteroatoms doped into the negative electrode carbon material and applying this to the testing of negative electrode carbon materials.

[0007] An object of the present disclosure is to provide a method for inspecting a negative electrode carbon material of a lithium ion battery with improved inspection accuracy, based on the results of a quantitative evaluation of the contribution to battery performance of each chemical bond state or functional group that a heteroatom doped in the negative electrode carbon material can take. Another problem to be solved by another embodiment of the present disclosure is to provide an inspection device for inspecting a negative electrode carbon material of a lithium ion battery for carrying out the inspection method. [Means for solving the problem]

[0008] Means for solving the above problems include the following aspects. <1> A step (S1) of producing a negative electrode carbon material for a lithium ion battery; A step (S2) of measuring the BET specific surface area S of the negative electrode carbon material; The surface of the negative electrode carbon material is subjected to a chemical bond state analysis by X-ray photoelectron spectroscopy (XPS) to determine the chemical bond state of the heteroatoms present on the surface or the abundance ratio r of each functional group (n). n (n is a subscript representing a chemical bond state or a type of functional group), Li for each of the chemical bond states or functional groups (n) + Activation energy E in the desolvation reaction model of an (n is a subscript representing a chemical bond state or a type of functional group) The activation energy E an from the Boltzmann factor F Bn (n is a subscript representing a chemical bond state or a type of functional group) The S and the r n and the product of F Bn a step (S6) of determining whether the negative electrode carbon material is good or bad by comparing a judgment value, which is the sum of the products of A method for inspecting a negative electrode carbon material of a lithium ion battery, comprising: <2> The negative electrode carbon material is a nitrogen-doped negative electrode carbon material; <1> A method for inspecting the negative electrode carbon material of a lithium ion battery according to claim 1. <3> An inspection device for a negative electrode carbon material of a lithium ion battery, comprising: A first measuring section for measuring the BET specific surface area S of the negative electrode carbon material; The surface of the negative electrode carbon material is subjected to a chemical bond state analysis by X-ray photoelectron spectroscopy (XPS) to determine the chemical bond state of the heteroatoms present on the surface or the abundance ratio r of each functional group (n). n A second measurement unit for calculating A first program for calculating at least the S, and the r n and a second program for calculating Li for each of the chemical bond states or functional groups (n). + Activation energy E in the desolvation reaction model of an (n is a subscript representing a chemical bond state or a type of functional group), and a third program for calculating the activation energy E an from the Boltzmann factor F Bn (n is a subscript representing a chemical bond state or a type of functional group), and a fourth program for calculating S and r n and the product of F Bn a storage unit that stores therein a fifth program for determining whether the negative electrode carbon material is good or bad by comparing a judgment value, which is the sum of the products of 13. An inspection apparatus for inspecting anode carbon materials of a lithium ion battery, comprising: <4> The negative electrode carbon material is a nitrogen-doped negative electrode carbon material; <3> An inspection device for the negative electrode carbon material of the lithium ion battery described in claim 1. Effect of the Invention

[0009] According to one embodiment of the present disclosure, there is provided a method for inspecting a negative electrode carbon material of a lithium ion battery with improved inspection accuracy, based on the results of a quantitative evaluation of the contribution to battery performance of each possible chemical bond state or functional group of heteroatoms doped into the negative electrode carbon material. According to another embodiment of the present disclosure, there is provided an inspection device for inspecting a negative electrode carbon material of a lithium ion battery for carrying out the inspection method. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic process diagram showing an example of a method for inspecting a negative electrode carbon material of a lithium ion battery according to the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram showing an example of the chemical bond state or functional group of a heteroatom doped in a negative electrode carbon material according to the inspection method of a negative electrode carbon material for a lithium ion battery of the present disclosure. [Diagram 3] FIG. 3 is a flow diagram showing an example of the process in step (S4) of the inspection method for a negative electrode carbon material of a lithium ion battery according to the present disclosure. [Figure 4] FIG. 4 is a schematic diagram showing an example of the process in step (S4) of the inspection method for a negative electrode carbon material of a lithium ion battery according to the present disclosure. [Diagram 5] FIG. 5 is a plot showing the relationship between the total energy of the system in the Li+ desolvation reaction model in step (S4) of the inspection method for the negative electrode carbon material of a lithium ion battery of the present disclosure and the distance d between the solvation model MS and the heteroatom-doped negative electrode carbon material model MC. [Figure 6] FIG. 6 is a schematic diagram showing another example of the chemical bond state or functional group of the heteroatom doped in the negative electrode carbon material in the inspection method of the negative electrode carbon material of the lithium ion battery of the present disclosure. [Figure 7] FIG. 7 is a schematic diagram showing an example of the configuration of an inspection device for a negative-electrode carbon material of a lithium-ion battery according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described. The description is for illustrating the embodiments and is not intended to limit the scope of the present disclosure.

[0012] In this specification, a numerical range indicated using "~" indicates a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in the present embodiment, the upper limit or lower limit of one numerical range may be replaced with the upper limit or lower limit of another numerical range described in the present embodiment. In addition, in the numerical ranges described in the present embodiment, the upper limit or lower limit of the numerical range may be replaced with a value shown in the examples.

[0013] In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

[0014] In this specification, when an embodiment is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0015] In this specification, each component may contain a plurality of corresponding substances. When the amount of each component in a composition is mentioned in this specification, if a plurality of substances corresponding to each component are present in the composition, the amount means the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0016] <Inspection method for negative electrode carbon material of lithium-ion batteries> A method for inspecting a negative electrode carbon material of a lithium ion battery according to an embodiment of the present disclosure includes: A step (S1) of producing a negative electrode carbon material for a lithium ion battery; A step (S2) of measuring the BET specific surface area S of the negative electrode carbon material; The surface of the negative electrode carbon material is subjected to a chemical bond state analysis by X-ray photoelectron spectroscopy (XPS) to determine the chemical bond state of the heteroatoms present on the surface or the abundance ratio r of each functional group (n). n (n is a subscript representing a chemical bond state or a type of functional group), Li for each of the chemical bond states or functional groups (n) + Activation energy E in the desolvation reaction model of an(n is a subscript representing a chemical bond state or a type of functional group) The activation energy E an from the Boltzmann factor F Bn (n is a subscript representing a chemical bond state or a type of functional group) The S and the r n and the product of F Bn a step (S6) of determining whether the negative electrode carbon material is good or bad by comparing a judgment value, which is the sum of the products of The method for inspecting a negative electrode carbon material of a lithium ion battery includes: By including the above process, the negative electrode carbon material of a lithium ion battery can be inspected based on the results of a quantitative evaluation of the contribution to battery performance of each possible chemical bond state or functional group of the heteroatom doped in the negative electrode carbon material, thereby improving the inspection accuracy.

[0017] Hereinafter, the method for inspecting the negative electrode carbon material of a lithium ion battery will be described in detail with reference to the drawings. Fig. 1 is a schematic process diagram showing an example of the method for inspecting the negative electrode carbon material of a lithium ion battery according to the present disclosure.

[0018] In the method for inspecting a negative electrode carbon material of a lithium ion battery according to the present disclosure, each step may be performed manually, or some or all of the steps may be controlled to be performed automatically.

[0019] -Process (S1)- In step (S1), a negative electrode carbon material for a lithium ion battery is produced.

[0020] The negative electrode carbon material of the lithium ion battery is preferably a heteroatom-doped negative electrode carbon material, such as a nitrogen-doped negative electrode carbon material, a sulfur-doped negative electrode carbon material, or a boron-doped negative electrode carbon material.

[0021] Hereinafter, the nitrogen-doped negative electrode carbon material will be described as an example.

[0022] First, a base carbon material and a nitrogen source are mixed together.

[0023] Examples of carbon materials include acetylene black, ketjen black, expanded graphite, carbon nanotubes (CNTs), and polyacetylene.

[0024] Examples of the nitrogen source include nitrogen-containing cyclic compounds such as polyacrylonitrile, N-methylpyrrolidone, pyridine, melamine, and pyrrole; compounds having an amino group such as amino acids, urea, and aniline; compounds having an amide bond such as formamide, acetamide, and acetanilide; and compounds having a cyano group such as acetonitrile.

[0025] The kneading may be carried out by known means such as a high-pressure homogenizer, a rotary homogenizer, an ultrasonic homogenizer, a bead mill, a ball mill, a three-roll mill, a planetary mixer, a disper mixer, a Henschel mixer, or a kneader.

[0026] The amount of the nitrogen source may be, for example, 8 parts by mass to 12 parts by mass with respect to 100 parts by mass of the carbon material.

[0027] The kneaded carbon material and nitrogen source are then heated in an inert atmosphere. The heating temperature is not particularly limited, but is preferably 50° C. to 100° C. higher than the thermal decomposition temperature of the nitrogen source. For example, the heating temperature is 750° C. to 850° C. when the nitrogen source is polyacrylonitrile.

[0028] The heating time is not particularly limited, but is preferably sufficient for the nitrogen source to be thermally decomposed. For example, when the nitrogen source is polyacrylonitrile, the heating time is 1 hour to 2 hours. The heating time sufficient for the thermal decomposition is TG-M S It may also be estimated by kinetic analysis of the thermal decomposition reaction by

[0029] The nitrogen source liquefied or vaporized by high temperature comes into contact with the highly reactive sites of graphite, whereby the carbon atoms of the highly reactive sites of graphite are substituted with nitrogen elements or nitrogen elements are added onto the carbon atoms, thus obtaining a nitrogen-doped negative electrode carbon material. The remaining nitrogen source is thermally decomposed and removed from the kneaded product.

[0030] In this manner, a nitrogen-doped negative electrode carbon material can be produced.

[0031] -Process (S2)- In the next step (S2), the BET specific surface area S of the negative electrode carbon material is measured.

[0032] The BET specific surface area S is a value calculated by analyzing an adsorption / desorption isotherm obtained by measuring the adsorption / desorption of nitrogen gas (at a temperature of −196° C.) using a multipoint BET (Brenauer-Emmet-Telle) method, and can be measured using a known measuring device (for example, a high-precision automatic gas / vapor adsorption measuring device (BELSORP MAX, manufactured by BEL Japan, Inc.)). It is preferable to vacuum-dry the measurement sample at a temperature of 150° C. for 6 hours before the measurement.

[0033] The BET specific surface area of ​​the negative electrode carbon material is, for example, 1 m 2 / g~1,000m 2 When the BET specific surface area is within the above range, good electrical conductivity is easily obtained, and the material is suitable for use as a negative electrode material.

[0034] -Process (S3)- In the next step (S3), the surface of the negative electrode carbon material is subjected to a chemical bond state analysis by X-ray photoelectron spectroscopy (XPS) to determine the chemical bond state of the heteroatoms present on the surface or the abundance ratio r of each functional group (n). n (n is a subscript representing the chemical bond state or the type of functional group).

[0035] Hereinafter, the nitrogen-doped negative electrode carbon material will be described as an example.

[0036] When the negative electrode carbon material is a nitrogen-doped negative electrode carbon material, the nitrogen atoms present on the surface of the negative electrode carbon material have five chemical bond states or functional groups, namely, pyridine type (1), amine type (2), pyrrole type (3), quaternary type (4), and pyridone type (5), as shown in Figure 2.

[0037] Here, in the nitrogen N1s spectrum obtained by XPS measurement, the pyridine type (1) gives a peak in the binding energy range of 398.3 eV to 398.7 eV. The amine type (2) gives a peak in the binding energy range of 399.3 eV to 399.7 eV. The pyrrole type (3) gives a peak in the binding energy range of 400.3 eV to 400.7 eV. The quaternary type (4) gives a peak in the binding energy range of 401.0 eV to 401.4 eV. The pyridone type (5) gives a peak in the binding energy range of 402.7 eV to 403.1 eV. The peaks obtained by measurement are treated as Gaussian functions, and are optimized and fitted with the peak intensity, peak position, and peak half-width as parameters, and are divided into the above peaks.

[0038] The area ratio of the divided peaks indicates the proportion of each chemical bond state or functional group (n). Therefore, by dividing the peak area corresponding to each chemical bond state or functional group by the sum of the peak areas, the abundance ratio r of each chemical bond state or functional group (n) in the N1s spectrum can be calculated. n (Here, r1 to r5) are obtained.

[0039] The above five chemical bond states or functional groups can be summarized as shown in Table 1 below.

[0040] [Table 1]

[0041] -Process (S4)- In the next step (S4), Li + Activation energy E in the desolvation reaction model of an(n is a subscript representing the chemical bond state or the type of functional group).

[0042] The calculation is performed using commercial software such as Gaussian 16W, GAMESS, Spartan, etc. The calculation accuracy is preferably good, and for example, conditions using B3LYP / 6-31G(d,p) and B3LYP / 6-31G(d) as functionals / basis functions are preferred. In addition, it is preferable to use the polarized dielectric model method (PCM method) for the calculation, taking into account the solvent effect. In this case, any value may be used as the dielectric constant of the solvent, for example, the dielectric constant of ethylene carbonate (EC) may be set to 90.

[0043] The calculation method will be described below with reference to FIG.

[0044] Solvent molecules are Li + Solvated model M coordinated to S The solvent may be appropriately selected from carbonate solvents such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC).

[0045] The solvation model M S The structure is optimized and the total energy E(S) is calculated.

[0046] Heteroatom-doped negative electrode carbon material model M C Create a heteroatom-doped negative electrode carbon material model M C may be a minimum unit including a heteroatom-doped site, but may also be an extended conjugated system based on a carbon skeleton.

[0047] The model M of the heteroatom-doped negative electrode carbon material C The structure is optimized and the total energy E(C) is calculated.

[0048] Next, the solvation model M Sand heteroatom-doped negative electrode carbon material model M C For example, the heteroatom-doped negative electrode carbon material model M C Heteroatoms and solvation model M S Li + and are arranged so that they face each other, and the structure is optimized.

[0049] Next, the total energy (E'(S)+E'(C)) is calculated at a distance D (for example, 15 Å as a non-interacting distance).

[0050] Next, the solvation model M S Li + The heteroatom-doped negative electrode carbon material model M C The solvation model M S Solvent molecules and heteroatom-doped anode carbon material model M C The relative positions of the

[0051] Calculate the total energy (E''(S)+E''(C)).

[0052] Solvation Model M S Li + and heteroatom-doped negative electrode carbon material M C The above process is repeated until the distance between the heteroatom and the heteroatom is less than x Å (for example, x=2 Å).

[0053] When the distance is less than x Å, the total energy (E'''(S) + E'''(C) reaches its maximum value E max Request.

[0054] Next, E max Calculate -E(S)-E(C) and Li + Activation energy E of the desolvation process of a Calculate.

[0055] The above process is carried out for each chemical bond state or functional group (n) of the heteroatom-doped portion.

[0056] -Process (S5)- In the next step (S5), the activation energy E an from the Boltzmann factor F Bn (n is a subscript that indicates the chemical bond state or the type of functional group). The Boltzmann factor F Bn can be calculated by the following formula:

[0057]

number

[0058] In the formula, E an is the activation energy corresponding to the chemical bond state or functional group (n), and R is the gas constant 8.314 Jmol -1 K -1 where T is absolute temperature in K.

[0059] Li + Activation energy E in the desolvation reaction model of an and the Boltzmann factor F Bn E may be calculated every time the negative electrode carbon material is inspected. Also, instead of calculating every time an inspection is performed, a previously calculated value may be stored in the memory of the inspection device and E may be calculated whenever necessary, such as when calculating the judgment value for the next process or later. an or F Bn It is also possible to read out and use it in the calculation. By saving it, the value can be reused, so the step (S4) can be performed with the activation energy E a The step (S4-1) of reading out the Boltzmann factor F B This can be replaced with a step (S5-1) of reading out the signal from the memory 14. This can simplify the inspection process.

[0060] -Process (S6)- In the next step (S6), the specific surface area S of the negative electrode carbon material and the abundance ratio r of each chemical bond state or functional group (n) are n and the Boltzmann factor F BnThe judgment value, which is the sum of the products of and, is compared with a threshold value to judge the quality of the negative electrode carbon material. By comparing the judgment value with the threshold value, the quality of the negative electrode carbon material of the lithium ion battery can be judged.

[0061] The pass / fail judgment is performed as follows: if the judgment value is equal to or greater than a threshold, the product is judged as pass, and if the judgment value is less than the threshold, the product is judged as defective.

[0062] (Judgment value) The judgment value is calculated by dividing the specific surface area S of the negative electrode carbon material by the chemical bond state or the abundance ratio r of the functional group (n), as shown in the following formula. n and the Boltzmann factor F Bn The sum of the products of and .

[0063]

number

[0064] In the formula, S is the specific surface area of ​​the negative electrode carbon material.

[0065] Here, the larger the specific surface area S of the negative electrode carbon material, the faster the charging reaction of the lithium ion battery tends to be. On the other hand, the smaller the specific surface area S of the negative electrode carbon material, the slower the charging reaction of the lithium ion battery tends to be. In other words, the specific surface area S of the negative electrode carbon material is proportional to the reaction resistance R during the charging process of the lithium ion battery. ct It is proportional to the inverse of and is involved in battery performance. Therefore, by incorporating the specific surface area S of the negative electrode as a parameter of the judgment value, the accuracy of the judgment of the quality of the negative electrode carbon material can be improved.

[0066] In the inspection method of the present disclosure, in particular, the specific surface area S of the negative electrode carbon material is calculated by dividing the chemical bond state or the abundance ratio r n S multiplied by r nThat is, the specific surface area S is distributed according to the chemical bonding state of the heteroatoms or the abundance ratio of the functional groups in the negative electrode material, and reflects the actual surface state. Therefore, the judgment value used in the inspection method of one embodiment of the present disclosure is associated with the actual surface state of the negative electrode carbon material, and the use of this judgment value improves the accuracy of the pass / fail judgment of the negative electrode carbon material.

[0067] In addition, the Boltzmann factor F Bn The larger the value of is, the faster the reaction tends to be. On the other hand, the Boltzmann factor F Bn The smaller the value of F, the slower the reaction tends to be. Bn Also, the reaction resistance R during the charging process of a lithium-ion battery ct It is proportional to the inverse of and is involved in the battery performance. Therefore, the Boltzmann factor F Bn By incorporating this, the accuracy of determining whether the negative electrode carbon material is good or bad can be improved.

[0068] The judgment value used in the inspection method of the present disclosure is further determined by the specific surface area S of the negative-electrode carbon material and the abundance ratio r of each chemical bond state or functional group (n) in order to reflect the overall state of the negative-electrode carbon material. n and the Boltzmann factor F Bn All the products of and are added together. This is a highly accurate index for determining whether the negative electrode carbon material is good or bad. Therefore, by using the above-mentioned determination value to determine whether the negative electrode carbon material is good or bad, the inspection accuracy can be improved.

[0069] Hereinafter, the judgment value will be described taking as an example a case where the negative electrode carbon material is a nitrogen-doped negative electrode carbon material.

[0070] When the negative electrode carbon material is a nitrogen-doped negative electrode carbon material, the judgment value is S×r1×F B1 +S×r2×F B2 +S×r3×F B3 +S×r4×F B4 +S×r5×F B5 In the judgment value, the contribution of pyridine type (1) is S × r1 × F B1In the judgment value, the contribution of amine type (2) is S × r2 × F B2 In the judgment value, the contribution of pyrrole type (3) is S×r3×F B3 In the judgment value, the contribution of the quaternary type (4) is S×r4×F B4 In the judgment value, the contribution of pyridone type (5) is S×r5×F B5 It becomes.

[0071] For the above five chemical bond states or functional groups, the calculation results are, for example, as shown in Table 2 below, and the BET specific surface area S = 4.0 m 2 / g, the judgment value is 3.46×10 -13 m 2 / g.

[0072] [Table 2]

[0073] Although the judgment value may be less accurate than the judgment value shown by the above formula, the judgment value shown by the following formula may be used instead of the judgment value shown by the above formula.

[0074]

number

[0075] In the formula, r n is the abundance ratio of the chemical bond state or functional group (n), and F Bn is the Boltzmann factor.

[0076] In addition, the judgment value is less accurate than the judgment value shown by the above formula, but it is possible to obtain a non-nitrogen doped benzene molecule by Li + The acceptor was Li + Activation energy E in the desolvation reaction model of an Calculate the activation energy E an Activation energy E below an The abundance ratio r of chemical bond states or functional groups (n) having nIt can also be the sum of.

[0077] In this case, for the above five chemical bond states or functional groups, the calculation results are, for example, as shown in Table 3 below, and the judgment value is calculated to be 0.41.

[0078] [Table 3]

[0079] (Threshold) The threshold value may be determined arbitrarily. For example, a coin cell is assembled using the negative electrode carbon material of the lithium ion battery of the present disclosure as the negative electrode and Li as the counter electrode, and the reaction resistance R obtained by measuring the AC impedance is ct It may be determined appropriately based on the above.

[0080] Threshold is 3.2×10 -13 m 2 / g, the above judgment value (3.46 × 10 -13 m 2 / g) is determined to be equal to or greater than the threshold value, so that the product can be determined to be non-defective.

[0081] According to the method described above, one embodiment of the present disclosure can provide a method for inspecting a negative electrode carbon material of a lithium ion battery with improved inspection accuracy.

[0082] Although the above describes an example of five chemical bond states or functional groups (bond states or functional groups of five types of nitrogen-doped portions), chemical bond states or functional groups other than the above five can also be judged in a similar manner, thereby improving the inspection accuracy.

[0083] In addition, although the above description has focused on the case of nitrogen doping, the atoms doped into the carbon material are not limited to nitrogen. For example, a sulfur-doped carbon material doped with sulfur atoms can also be evaluated in the same manner as above, thereby improving the inspection accuracy.

[0084] In addition, among the solvent molecules constituting the electrolyte, it is preferable to use the molecules for which the desolvation process is rate-limiting (the activation energy of the desolvation process is large) as the solvent molecules of the solvation molecule model. For example, in the case of an electrolyte composed of EC and DMC (dimethyl carbonate), since the activation energy of the desolvation process of EC is larger than the activation energy of the desolvation process of DMC, it is preferable to select EC as the solvation molecule model. However, it is not necessary to select EC as the solvent molecule of the solvation molecule model, and as described above, any solvent molecule can be selected. For example, even if the solvent molecule is replaced with EMC (ethyl methyl carbonate), PC (propylene carbonate), etc., it can be judged in the same manner as above, and the inspection accuracy can be improved. The non-nitrogen-doped portion of the negative electrode partial structure may contain multiple ring structures. For example, even if the model shown in FIG. 6 is used instead of the pyridine-type nitrogen-doped negative electrode model described above, the determination can be performed in the same manner as above, and the inspection accuracy can be improved.

[0085] Above, we have considered the solvation model as + Although the above description has focused on the case where one solvent molecule is used for the solvation model, a solvation model with multiple solvent molecules may also be used.

[0086] <Inspection equipment> Another embodiment of the present disclosure is an inspection device for a negative electrode carbon material of a lithium ion battery, comprising: A first measuring section for measuring the BET specific surface area S of the negative electrode carbon material; The surface of the negative electrode carbon material is subjected to a chemical bond state analysis by X-ray photoelectron spectroscopy (XPS) to determine the chemical bond state of the heteroatoms present on the surface or the abundance ratio r of each functional group (n). n (n is a subscript representing a chemical bond state or a type of functional group), A first program for calculating at least the S, and the r n and a second program for calculating Li for each of the chemical bond states or functional groups (n). + Activation energy E in the desolvation reaction model ofan (n is a subscript representing a chemical bond state or a type of functional group), and a third program for calculating the activation energy E an from the Boltzmann factor F Bn (n is a subscript representing a chemical bond state or a type of functional group), and a fourth program for calculating S and r n and the product of F Bn a storage unit that stores therein a fifth program for determining whether the negative electrode carbon material is good or bad by comparing a judgment value, which is the sum of the products of The present invention relates to an inspection device for a negative electrode carbon material of a lithium ion battery, the device including: By using the inspection device of the present disclosure, it is possible to carry out an inspection method for a negative electrode carbon material of a lithium ion battery with improved inspection accuracy according to one embodiment of the present disclosure.

[0087] The configuration of the inspection device will be described below. Fig. 7 is a schematic diagram showing an example of the configuration of an inspection device for a negative-electrode carbon material of a lithium-ion battery according to the present disclosure. In Fig. 7, the inspection device 100 includes a first measurement unit 10, a second measurement unit 20, and a storage unit 30, and the first measurement unit 10, the second measurement unit 20, and the storage unit 30 are electrically connected via a network.

[0088] -1st measurement section- The first measuring section measures the BET specific surface area S of the negative electrode carbon material. The first measuring section is not particularly limited as long as it can measure the BET specific surface area S of the negative electrode carbon material. For example, a commercially available high-precision automatic gas / vapor adsorption measuring device (e.g., BELSORP MAX, manufactured by BEL JAPAN, Inc.) can be used.

[0089] -Second measurement section- The second measurement unit measures the abundance ratio r of each chemical bond state or functional group (n) of heteroatoms present on the surface of the negative electrode carbon material of the lithium ion battery. nIn order to calculate the above, the surface of the negative electrode carbon material is subjected to chemical bond state analysis and measurement by X-ray photoelectron spectroscopy (XPS). The second measurement unit is not particularly limited as long as it can achieve the above-mentioned purpose. For example, a commercially available photoelectron spectroscopy (XPS) (e.g., JPS-9030, manufactured by JEOL Ltd.) can be used.

[0090] -Storage Department- The storage unit includes at least a first program for calculating the S, and n and a second program for calculating Li for each of the chemical bond states or functional groups (n). + Activation energy E in the desolvation reaction model of an (n is a subscript representing a chemical bond state or a type of functional group), and a third program for calculating the activation energy E an from the Boltzmann factor F Bn (n is a subscript representing a chemical bond state or a type of functional group), and a fourth program for calculating S and r n and the product of F Bn and a fifth program for comparing a judgment value, which is the sum of products of the above and a threshold value, with the result that the negative electrode carbon material is good or bad.

[0091] The first program automatically analyzes the results of measuring the adsorption of the negative electrode carbon material to calculate the specific surface area S. The first program may be a known program. The second program automatically analyzes the results of measuring the surface of the negative electrode carbon material to calculate the chemical bond state or the abundance ratio r of each functional group (n). n The second program may be a known program. The third program calculates Li + Activation energy E in the desolvation reaction model of an The third program may be a known program. The fourth program calculates the activation energy E an from the Boltzmann factor F Bn The fifth program calculates the S and the r n and the product of F Bn The negative electrode carbon material is judged to be good or bad by comparing a judgment value, which is the sum of the products of these, with a threshold value.

[0092] Moreover, the inspection device preferably includes an input section, an output section, and a control and calculation section in addition to the above-mentioned first measurement section, second measurement section, and storage section.

[0093] - Input section - Examples of the input unit include a keyboard, a mouse, and a touch panel.

[0094] - Output section - Examples of the output unit include a liquid crystal display and a touch panel.

[0095] -Control and calculation section- The control calculation unit may be a device having a calculation processing function such as a CPU.

[0096] According to the inspection device for the negative electrode carbon material of a lithium ion battery of another embodiment of the present disclosure described above, it is possible to execute the inspection method for the negative electrode carbon material of a lithium ion battery of the present disclosure with improved inspection accuracy, thereby improving the inspection accuracy. [Explanation of symbols]

[0097] 10 1st measurement section 20 Second measuring section 30 Storage section 40 Input section 50 Output section 60 Control and calculation section 100 Inspection Equipment

Claims

1. A step (S1) of producing a negative electrode carbon material for a lithium ion battery; A step (S2) of measuring a BET specific surface area S of the negative electrode carbon material; The surface of the negative electrode carbon material is subjected to a chemical bond state analysis by X-ray photoelectron spectroscopy (XPS) to determine the chemical bond state of the heteroatoms present on the surface or the abundance ratio r of each functional group (n). ｎ (n is a subscript representing a chemical bond state or a type of functional group) Li for each of the chemical bond states or functional groups (n) ＋ Activation energy E in the desolvation reaction model ａｎ (n is a subscript representing a chemical bond state or a type of functional group) The activation energy E ａｎ From the Boltzmann factor F Ｂｎ (n is a subscript representing a chemical bond state or a type of functional group) The S and the r ｎ and the product of F Ｂｎ a step (S6) of determining whether the negative electrode carbon material is good or bad by comparing a judgment value, which is the sum of the products of A method for inspecting a negative electrode carbon material of a lithium ion battery, comprising:

2. The method for inspecting a negative electrode carbon material of a lithium ion battery according to claim 1 , wherein the negative electrode carbon material is a nitrogen-doped negative electrode carbon material.

3. An inspection device for a negative electrode carbon material of a lithium ion battery, comprising: a first measuring section for measuring a BET specific surface area S of the negative electrode carbon material; The surface of the negative electrode carbon material is subjected to a chemical bond state analysis by X-ray photoelectron spectroscopy (XPS) to determine the chemical bond state of the heteroatoms present on the surface or the abundance ratio r of each functional group (n). ｎ (n is a subscript representing a chemical bond state or a type of functional group), A first program for calculating at least the S; ｎ A second program for calculating Li for each of the chemical bond states or functional groups (n) ＋ Activation energy E in the desolvation reaction model ａｎ (n is a subscript representing a chemical bond state or a type of functional group), and ａｎ From the Boltzmann factor F Ｂｎ (n is a subscript representing a chemical bond state or a type of functional group), and a fourth program for calculating S and r ｎ and the product of F Ｂｎ a fifth program for determining whether the negative electrode carbon material is good or bad by comparing a judgment value, which is the sum of the products of 13. An inspection apparatus for inspecting anode carbon materials of a lithium ion battery, comprising:

4. 4. The inspection device for a negative electrode carbon material of a lithium ion battery according to claim 3, wherein the negative electrode carbon material is a nitrogen-doped negative electrode carbon material.

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