JP7300181B2 - BATTERY MANAGEMENT SYSTEM AND BATTERY MANAGEMENT METHOD - Google Patents

Description

The present invention relates to a battery management system and a battery management method.

Toward the realization of a low-carbon society, there is a trend to expand the scope of application of chargeable/dischargeable secondary batteries such as lithium ion batteries (hereinafter referred to as “LiB”) to in-vehicle and stationary applications. In addition, the application range of secondary batteries such as LiB is expanding from consumer use to infrastructure use.

The in-vehicle application of the secondary battery refers to the installation of the secondary battery in an electric vehicle (hereinafter referred to as “xEV”). Since the cruising range of mobility including xEV depends on the capacity of the secondary battery, the secondary battery is an important component in improving the performance of mobility. According to Non-Patent Document 1, the target is to increase the energy density of a secondary battery as a storage battery for xEV to 500 Wh/kg or more by 2030.

The stationary use of the secondary battery refers to the storage of electric energy obtained by an energy harvester (hereinafter referred to as "EH") including photovoltaic power generation and wind power generation. EH is an unstable power source compared to thermal power generation that utilizes fossil fuels, because the amount of power generated is affected by the weather and the like. Therefore, the secondary battery is also an important component in stabilizing power supply.

Common to these applications, battery management (hereinafter referred to as "BM") technology that can evaluate parameters such as the amount of charge and internal resistance of secondary battery cells is a secondary technology for systems such as xEV and EH. It is one of the important technologies in the introduction of batteries. In common with these applications, the BM technology capable of evaluating the charge/discharge state of a secondary battery cell is one of the important technologies.

In other words, the BM technology that can evaluate the cycle life of the secondary battery cell as the period during which the system such as xEV/EH can exhibit the performance required is one of the important technologies. In addition, BM technology, which is capable of diagnosing deterioration and predicting failure of secondary battery cells, is one of the important technologies.

A deterioration mechanism of a secondary battery cell such as LiB is grasped as follows, for example.
- Guest cations M ⁺ (for example, Li ⁺ ) remain inserted into the host negative electrode active material and are no longer extracted from the host negative electrode active material, resulting in a decrease in the total amount of active guest cations M ⁺ .
- Guest cations M 2 ⁺ are reduced on the surface of the host negative electrode active material and react with the electrolyte, thereby reducing the total amount of active guest cations M 2 ⁺ in the secondary battery cell.
- Formation of a film on the surface of the host negative electrode active material due to a chemical reaction with the electrolyte lowers the diffusion coefficient of the guest cation M ⁺ and increases the internal resistance of the secondary battery cell.

The performance index of secondary battery cells such as LiB is energy density based on parameters including discharge voltage and charge amount, or output density based on parameters including open circuit voltage, internal resistance, and current. Evaluable BM technology is one of the key technologies.

According to Patent Document 1, a battery configured to easily examine the optical properties of a surplus electrolyte of LiB, a battery system capable of detecting the lithium salt concentration of the surplus electrolyte, and a lithium salt concentration of the surplus electrolyte An invention is disclosed for a battery system capable of detecting and suppressing/reducing an increase in the internal resistance of the battery to recover the deterioration of the battery and keep the internal resistance within an appropriate range.

It can be understood that the invention described in Patent Document 1 is one of the BM techniques that can evaluate the above parameters based on optical measurement. However, the invention has room for improvement in terms of evaluating secondary battery cells based on optical measurement of active materials.

In principle, reversibility of charge/discharge in secondary batteries such as LiB is ensured by the intercalation reaction of guest cations M ⁺ with the active material as the host. At this time, the crystal structure of the host active material changes due to the insertion/extraction of the guest cation M ⁺ . Changes in the crystal structure in the host active material affect the storage of guest cations M ⁺ .

As exemplified by LMO materials, LiMnO ₂ having an R3-m structure undergoes a phase transition to spinel-type LiMn ₂ O ₄ due to repeated charging and discharging. In the LMO-based compound, the insertion of Li ⁺ into the vacant octahedral site is 3V vs. Tetragonal phase LiMn ₂ O ₄ is formed due to Jahn-Teller strain occurring below Li/Li ⁺ . At this time, the crystal structure of the LMO-based material is elongated in the c-axis direction and the particles are crushed, resulting in a decrease in capacity.

In view of the above circumstances, the BM technology capable of detecting the crystal structure in the active material of a secondary battery cell such as LiB and evaluating the charge/discharge state of the secondary battery is one of the important technologies.

Detection of the crystal structure in the active material of a secondary battery such as LiB (corresponding to structure determination) includes, for example, X-ray diffraction (XRD), which determines the crystal structure using X-ray diffraction, electron beam diffraction, and the like. It is realized by transmission electron microscopy (TEM), which determines the space group using analyses, and X-ray photoelectron spectroscopy (XPS), which determines the composition and chemical bonding state constituting the vicinity of the surface of the active material.

However, since the above XRD, TEM, XPS, etc. are analysis methods that require irradiation of X-rays and electron beams on the secondary battery, BM technology that can easily evaluate the active material in the secondary battery cell during operation in the system. It is difficult to say that it is a method that can realize

Further, to specify the elemental composition ratio in the active material of a secondary battery such as LiB, for example, the element species of the sample-constituting element is specified from the optical spectrum of the sample-constituting element ionized in an inductively coupled high-frequency plasma (ICP). Realized by ICP-AES.

However, the above-mentioned ICP-AES and the like are analysis methods that require plasma to identify the elemental composition ratio (for example, corresponding to the amount of guest cation M ⁺ in the active material) in the secondary battery, so it can be operated in the system. It is hard to say that it is a method that can realize a BM technology that can easily evaluate the active material of the secondary battery inside.

Raman spectroscopy is known as an optical technique for detecting a crystal structure in an active material of a secondary battery such as LiB. Since the optical method is an analysis method using light waves including visible light, it can easily evaluate the active material of the secondary battery compared to the methods such as XRD, TEM, XPS, and ICP-AES. It can be understood that it is an analytical method.

However, since Raman spectroscopy is an analysis method that requires post-processing such as peak separation and peak shape evaluation for analysis data in the process of obtaining a wide range of information including the crystal grain size of the active material, It is difficult to say that this is a method that can realize a BM technique that can easily evaluate active materials in cells.

Japanese Patent Application Laid-Open No. 2010-232080

New Energy and Industrial Technology Development Organization (NEDO), “Secondary Battery Technology Development Roadmap 2013 (Battery RM 2013)”, NEDO, August 2013.

In view of the above circumstances, an object of the present invention is to provide a novel BM technique.

In order to solve the above-mentioned problems, the present invention provides a battery management system, comprising: measuring means for measuring optical density in a region containing at least part of an active material constituting a secondary battery cell; evaluation means for evaluating the charge/discharge state of the secondary battery cell based on the above. With such a configuration, the present invention provides a BM technology that can easily evaluate the performance of a secondary battery cell based on at least the optical density corresponding to the amount of light absorption in the active material of the secondary battery cell. be able to. In addition, with such a configuration, the present invention contributes to optimization of secondary battery cell monitoring by introducing the optical density of the secondary battery cell as a parameter to the conventional BM technology. can be done.

A preferred embodiment of the present invention is technically characterized in that the region includes at least part of the positive electrode active material, which is the active material. With such a configuration, the present invention can obtain, for example, the optical density, which is a measurement parameter related to the amount of guest cations M ⁺ stored in the positive electrode active material constituting the secondary battery cell. Further, with such a configuration, the present invention can obtain, for example, the optical density, which is a measurement parameter related to the crystal structure of the positive electrode active material that constitutes the secondary battery cell.

A preferred embodiment of the present invention is technically characterized in that the region includes at least part of the negative electrode active material, which is the active material. With such a configuration, the present invention can obtain, for example, the optical density, which is a measurement parameter related to the amount of guest cations M ⁺ stored in the negative electrode active material constituting the secondary battery cell. Further, with such a configuration, the present invention can, for example, obtain optical density, which is a measurement parameter related to the crystal structure of the negative electrode active material that constitutes the secondary battery cell.

A preferred form of the present invention is technically characterized in that the region further includes at least part of a current collector that constitutes the secondary battery cell. With such a configuration, the present invention can measure the optical density of an active material using, for example, a current collector, which is a transparent electrode, as an optical window.

A preferred form of the present invention is technically characterized in that the region further includes at least part of an electrolyte that constitutes the secondary battery cell. With such a configuration, the present invention can obtain an optical density that can be changed according to the formation of films/dendrites in the electrolyte.

In a preferred embodiment of the present invention, the measuring means is technically characterized in that the measurement light is incident on the region, the measurement light transmitted through the region is received, and the optical density is measured. With such a configuration, the present invention can provide an optical system capable of evaluating the performance of a secondary battery cell to a conventional power supply configuration including a secondary battery.

A preferred embodiment of the present invention is technically characterized in that the measurement light is single-wavelength light. Further, in a preferred form of the present invention, the technical feature is that the single-wavelength light is visible light. Further, in a preferred form of the present invention, the technical feature is that the single-wavelength light is ultraviolet light. Further, a preferred embodiment of the present invention is technically characterized in that the single-wavelength light is infrared light. By adopting such a configuration, the present invention takes into consideration the wavelength selectivity in the optical density of the active material constituting the secondary battery cell, and is exposed to the storage amount of the guest cation M ⁺ in the active material. A predetermined wavelength can be employed that depends on the .

A preferred embodiment of the present invention is characterized in that the measuring means performs operand measurements of the optical density and the charge/discharge capacity of the secondary battery cell. With such a configuration, the present invention can perform operand measurements of the electrical characteristics and optical characteristics of operating secondary battery cells that constitute systems such as xEV EH. Evaluation of the charge/discharge state of the secondary battery cell based on the optical density can be realized more preferably.

A preferred embodiment of the present invention is technically characterized in that the evaluation means determines charge/discharge capacity-optical density characteristics (COD characteristics) based on the charge/discharge capacity and optical density. With such a configuration, the present invention can evaluate the correlation between the electrical characteristics and optical characteristics of a secondary battery cell in operation that constitutes a system such as xEV EH. Evaluation of the charge/discharge state of the secondary battery cell based on the density can be realized more preferably.

In a preferred embodiment of the present invention, the evaluation means evaluates the CO based on the optical density and the charge/discharge capacity of the secondary battery cell at different numbers of cycles. D. characteristic cycle characteristics, and the CO. D. The technical feature is that the amount of voltage drop (ΔV) of the secondary battery cell is evaluated based on the amount of change in optical density (ΔO.D.) in the cycle characteristic of the characteristic. With such a configuration, the present invention evaluates the charge and discharge state of the secondary battery cell based on the correlation between the deterioration and optical characteristics of the secondary battery cell in operation that constitutes a system such as xEV EH. can be more suitably realized, and can contribute to the realization of deterioration prediction of secondary battery cells and the like.

A preferred embodiment of the present invention is characterized in that the evaluation means evaluates the amount of charge in the active material based on the optical density. With such a configuration, the present invention provides a BM technique that can easily evaluate the performance including the charge and discharge capacity of the secondary battery cell based on at least the optical density of the active material of the secondary battery cell. be able to.

Further, in order to solve the above problems, the present invention provides a battery management method, comprising: a measuring step of measuring an optical density in a region including at least part of an active material constituting a secondary battery cell; and an evaluation step of evaluating the charge/discharge state of the secondary battery cell based at least on the above. With such a configuration, the present invention can provide a BM technique that can easily evaluate the performance of a secondary battery cell based on at least the optical density of the active material of the secondary battery cell. In addition, with such a configuration, the present invention contributes to optimization of secondary battery cell monitoring by introducing the optical density of the secondary battery cell as a parameter to the conventional BM technology. can be done.

Further, in order to solve the above problems, the present invention provides a battery management system, which evaluates the charge and discharge state of the secondary battery cell based at least on the optical density in the area containing the active material of the secondary battery cell. It is technically characterized by comprising a computer having means. With such a configuration, the present invention provides a technology related to BM computing that can easily evaluate the performance of a secondary battery cell based at least on the optical density of the active material of the secondary battery cell. can be done.

Further, in order to solve the above problems, the present invention provides a battery management method, which evaluates the charge and discharge state of the secondary battery cell based at least on the optical density in the area containing the active material of the secondary battery cell. A technical feature is that the steps are executed by a processor of a computer. With such a configuration, the present invention provides a technology related to BM computing that can easily evaluate the performance of a secondary battery cell based at least on the optical density of the active material of the secondary battery cell. can be done.

Further, in order to solve the above problems, the present invention provides a battery management program, wherein a computer evaluates the charge and discharge state of the secondary battery cell based on at least the optical density in the area containing the active material of the secondary battery cell The technical feature is to function as an evaluation means for performing With such a configuration, the present invention provides a technology related to BM computing that can easily evaluate the performance of a secondary battery cell based at least on the optical density of the active material of the secondary battery cell. can be done.

The present invention can realize the provision of novel BM technology. "BM technology" includes a battery management system (hereinafter referred to as "BM system"), a battery management method (hereinafter referred to as "BM method"), and a battery management program (hereinafter referred to as "BM program". ) refers to a technical feature in at least one of

In addition, other problems, features, and advantages will be appropriately clarified by the "modes for carrying out the invention" taken up together with the drawings and claims.

1 shows a functional block diagram of a BM system 1 according to Embodiment 1. FIG. 4 shows a flowchart of BM according to Embodiment 1. FIG. FIG. 4 shows an explanatory diagram of optical characteristic measurement in the region 200 according to the first embodiment; FIG. 10 is an explanatory diagram of optical characteristic measurement in the region 200 according to the second embodiment; FIG. 11 is an explanatory diagram of optical characteristic measurement in the region 200 according to the third embodiment; FIG. 11 is an explanatory diagram of optical characteristic measurement in a region 200 according to Embodiment 4; FIG. 11 is an explanatory diagram of optical characteristic measurement in a region 200 according to Embodiment 5; 4 shows CV characteristics of the secondary battery cell 2 according to Example 1. FIG. 2 shows optical properties of a positive electrode active material 22 according to Example 1. FIG. CO of the secondary battery cell 2 according to Example 1. D. characterize. ΔO. of the secondary battery cell 2 according to Example 1. D. -ΔV characteristics are shown. 4 shows optical properties of a positive electrode active material 22 according to Example 2. FIG.

This specification describes the configuration, effects, and the like according to an embodiment of the present invention with reference to the drawings. The present invention is not limited to the following one embodiment, and can adopt various configurations. In addition, one embodiment of the present invention can adopt at least part of the configuration of each other as appropriate.

Each of the BM system 1 and the BM method has similar effects. Each means in the BM system 1 and each step in the BM method have similar effects.

Moreover, each of the BM system 1, the BM method, the BM program, and the BM program medium has similar effects. Each means of the BM system 1, the BM program, and the BM program medium and each step of the BM method have the same effect.

Note that the BM program medium refers to a non-transitory recording medium storing the BM program. The recording medium indicates, for example, non-volatile memory such as flash memory.

<<Embodiment 1>>
This specification describes Embodiment 1 of the present invention below. It should be noted that some of the reference numerals used in the description of this specification may not be illustrated.

As illustrated in FIG. 1, the BM system 1 includes measuring means 11 (corresponding to a measuring step) for measuring the optical density in the region 200 containing the active material of the secondary battery cell 2, and at least evaluation means 12 (corresponding to an evaluation step) for evaluating the charge/discharge state of the secondary battery cell 2 based on the evaluation means.

<Secondary battery cell 2>
The secondary battery cell 2 is a known or commonly used secondary battery that can be charged and discharged. The secondary battery cell 2 includes at least a current collector 21 , a positive electrode active material 22 , an electrolyte 23 and a negative electrode active material 24 . In addition, the secondary battery cell 2 may further include a binder, a separator, a conductive aid, an SEI film, and the like.

The secondary battery cell 2 is LiB as an example. Moreover, the secondary battery cell 2 is a sodium ion battery as an example. Moreover, the secondary battery cell 2 is an all-solid-state battery as an example. Moreover, the secondary battery cell 2 is a bulk-type all-solid-state battery as an example. Also, the secondary battery cell 2 is, for example, a thin-film type all-solid-state battery. The type of the secondary battery cell 2 is not limited as long as it is a chargeable/dischargeable metal ion battery.

Current collector 21 may employ a known or commonly used conductive material. The current collector 21 is made of, for example, a transparent electrode material such as indium tin oxide (ITO).

The positive electrode active material 22 functions as a host for guest cations M ⁺ (for example, Li ⁺ ) and provides desired Potential vs. There are no restrictions on the type of material as long as it is a material that guarantees M/M ⁺ . The positive electrode active material 22 is, for example, a Li--Nb--O based material or a Li--VO based material.

The type of the electrolyte 23 is not limited as long as it is a material that functions as an ionic conductor for guest cations M ⁺ (for example, Li ⁺ ) and ensures desired ionic conductivity. The electrolyte 23 may be a known or commonly used electrolytic solution, or a known or commonly used solid electrolyte.

The type of the negative electrode active material 24 is not limited as long as it functions as a host for guest cations M ⁺ (for example, Li ⁺ ) and ensures desired Capacity/mAh g ⁻¹ . The negative electrode active material 24 is, for example, a transparent material.

<Measuring Means 11>
The measuring means 11 (corresponding to a measuring device) emits measurement light 111c from the light source 111a to the region 200 along the stacking direction X of the current collector 21 and the active material, and transmits the measurement light transmitted through the region 200. 111c is received by the light receiving element 111b, and optical characteristic measuring means 111 (corresponding to an optical measuring instrument) is provided for measuring the optical density (OD) in the area 200. FIG.

It can be understood that the light receiving element 111 b receives the measurement light 111 c that has undergone reflection/multiple reflection in the area 200 . Further, it can be understood that the light receiving element 111b receives the measurement light 111c that has undergone refraction in the region 200. FIG. Further, it can be understood that the light receiving element 111b receives the measurement light 111c that has undergone scattering in the region 200. FIG. Further, it can be understood that the light receiving element 111b receives the measurement light 111c that has undergone absorption in the region 200. FIG. As an example, “the measurement light 111c that has undergone scattering in the region 200” in the description of this specification corresponds to the measurement light 111c scattered/dispersed in the region 200. FIG.

It can be understood that the light receiving element 111b receives the measurement light 111c that has undergone absorption/reflection/multiple reflection/refraction/scattering at the particle surface/particle boundary/near the area 200 and the like. Further, it can be understood that the light receiving element 111b receives the measurement light 111c that has undergone absorption/reflection/multiple reflection/refraction/scattering at or near the grain boundary of the region 200. FIG. Further, it can be understood that the light receiving element 111b receives the measurement light 111c that has undergone absorption/reflection/multiple reflection/refraction/scattering at/near the interface of the region 200, and the like. Further, it can be understood that the light receiving element 111b receives the measurement light 111c that has undergone absorption/reflection/multiple reflection/refraction/scattering in the local structure of the region 200/the vicinity thereof. There is no limit to the width of the neighborhood.

"Optical density" in the description herein corresponds to the amount of light absorption. Also, the optical density corresponds to the amount of coloring. Also, the optical density corresponds to a measurement parameter based on the ratio of incident light intensity and transmitted light intensity (corresponding to transmittance), and is expressed based on the common logarithm of the transmittance.

Here, the measuring means 11 has an optical property measuring means 111 which is known or commonly used optical means including a light source 111a and a light receiving element 111b. The light intensity and spot diameter of the measurement light 111c incident by the optical property measuring means 111 are not limited. The optical path length of the measurement light 111c in the optical characteristic measuring means 111 is not limited.

The light source 111a is an optical element including a known or commonly used oscillator capable of emitting measurement light 111c. The light source 111a may be, for example, a gas laser such as a He--Ne laser or an Ar laser, or a solid-state laser such as a YAG laser. It may be a semiconductor laser, and its active medium and excitation method are not limited. The light source 111a may be an optical element capable of emitting light such as white light.

The optical property measuring means 111 may further include a known or commonly used demultiplexing element/spectroscopic element. Also, light source 111a may further comprise a known or conventional grating. In addition, the light source 111a may further include an optical scanner capable of alignment (corresponding to focus position adjustment) and scanning of the measurement light 111c. The optical scanner is, for example, a known or commonly used galvanometer scanner that includes a galvanometer mirror, an axially rotating motor, and a condenser lens.

The light receiving element 111b is a known or commonly used optical element such as a photometer, spectrophotometer, or absorptiometer capable of measuring the light intensity of the measurement light 111c. Also, the light receiving element 111b may be a known or commonly used photodiode, or a known or commonly used laser sensor.

The measurement light 111c is, for example, single-wavelength light. Here, the single-wavelength light is, for example, visible light in the wavelength band of 380-700 nm, ultraviolet light in the wavelength band of 200-380 nm, or infrared light in the wavelength band of 0.7-2.5 μm. Note that the infrared light has a wavelength in a wavelength band of 2.5-4.0 μm, for example. The wavelength of the measurement light 111c in one embodiment of the present invention is not limited as long as it can be classified as a light wave. In addition, the said single wavelength light is a laser beam which has directivity as an example.

The measuring means 11 includes an electrical characteristic measuring means 112 (equivalent to an electrical measuring instrument) which is a known or commonly used means capable of measuring parameters including charge/discharge capacity (C), discharge voltage, and impedance of the secondary battery cell 2. have. The electrical property measuring means 112 performs known or conventional cyclic measurements (cycle tests) such as measuring the parameter at different number of cycles.

Here, the measurement means 11 performs operand measurement such that the measurement of the optical density of the region 200 by the optical property measurement means 111 and the measurement of the charge/discharge capacity of the secondary battery cell 2 by the electrical property measurement means 112 are performed simultaneously. / Real-time measurement / Real-time measurement is possible.

Note that the measuring means 11 may be configured to be able to measure the light intensity (corresponding to the incident light intensity) of the measurement light 111c when it does not pass through the region 200 . The light intensity can optionally be used to measure (determine) the optical density of region 200 . The light intensity may be measured by the light receiving element 111b, or may be measured by another light receiving element different from the light receiving element 111b.

<Evaluation Means 12>
The evaluation means 12 evaluates the charge/discharge state of the secondary battery cell 2 based at least on the optical density measured by the measurement means 11 .

The “charged/discharged state” in the description of this specification indicates, for example, the remaining performance (corresponding to performance) of the secondary battery cell 2 . Moreover, the charge/discharge state indicates, for example, the electrical characteristics of the secondary battery cell 2 . Further, the charge/discharge state indicates, for example, any one or a combination of charge/discharge capacity, internal resistance, and open-circuit voltage of the secondary battery cell 2 . Further, the charge/discharge state indicates, for example, a charge/discharge level corresponding to the remaining capacity during charge/discharge/consumption. Also, the charge/discharge state is an example. The degree/state of deterioration or failure of the secondary battery cell 2 is shown. Moreover, the charge/discharge state indicates, for example, the cycle life of the secondary battery cell 2 .

The evaluation means 12 determines charge/discharge capacity-optical density characteristics (COD characteristics) based on the charge/discharge capacity and optical density measured by the measurement means 11 .

Evaluation means 12 calculates CO.O. D. to determine the cycle characteristics of the characteristic; D. The amount of voltage drop (ΔV) of the secondary battery cell 2 is evaluated based on the amount of change in optical density (ΔO.D.) in the cycle characteristic of the characteristic. At this time, the evaluation means 12 determines the ΔO. D. Further based on the -ΔV characteristic, the ΔV is evaluated.

"ΔO.D." in the description of this specification is, for example, the optical density when the secondary battery cell 2 (cycle number = 1) exhibits a predetermined charge-discharge capacity, and the secondary battery cell 2 (cycle (number≧2), it corresponds to the difference between the optical density and the optical density when the predetermined charge/discharge capacity is exhibited. The predetermined charge/discharge capacity is, for example, 0 mAh/g. In addition, "ΔV" in the description in this specification is, for example, the open-circuit voltage in the secondary battery cell 2 (number of cycles = 1) and the open-circuit voltage in the secondary battery cell 2 (number of cycles ≥ 2). Equivalent to difference.

The evaluation means 12 is based on the CO. D. Based on the cycle characteristics of the characteristics, evaluation of the charge/discharge state including any of deterioration diagnosis, failure prediction, and cycle life evaluation of the secondary battery cell 2 may be performed. Specifically, the evaluation means 12 determines C and/or ΔO. D. exceeds a predetermined threshold value, the secondary battery cell 2 may be evaluated as corresponding to a predetermined state (for example, a deteriorated state or a failure state). It can be understood that the predetermined threshold value is set in advance based on the optical properties of the material included in the region 200 (for example, wavelength dependence of optical density).

The evaluation means 12 calculates the number of cycles-ΔO. D. Evaluation of the charge/discharge state including any of deterioration diagnosis, failure prediction, and cycle life evaluation of the secondary battery cell 2 may be performed based on the slope of the characteristic. Specifically, the evaluation means 12 is configured to evaluate that the secondary battery cell 2 is in a predetermined state (for example, a deteriorated state or a failure state) when the gradient exceeds a predetermined threshold. It's okay. It can be understood that the predetermined threshold value is set in advance based on the optical properties of the material included in the region 200 (for example, wavelength dependence of optical density).

The evaluation means 12 is based on the CO. D. Based on a prediction model in which at least one of various parameters related to characteristics (for example, C, OD, ΔO.D., cycle number-ΔO.D. gradient in characteristics) is input It may be configured to perform an evaluation. The predictive model may be, for example, a statistical model. Also, the prediction model may be, for example, a machine learning model such as a deep learning model, and there is no restriction on the presence or absence of training data.

The evaluation means 12 determines the ΔO. D. Based on the slope of the -ΔV characteristic, evaluation of the charge/discharge state including any of deterioration diagnosis, failure prediction, and cycle life evaluation of the secondary battery cell 2 may be performed. Specifically, the evaluation means 12 is configured to evaluate that the secondary battery cell 2 is in a predetermined state (for example, a deteriorated state or a failure state) when the gradient exceeds a predetermined threshold. It's okay. It can be understood that the predetermined threshold value is set in advance based on the optical properties of the material included in the region 200 (for example, wavelength dependence of optical density).

The evaluation means 12 determines the ΔO. D. By determining the probability of reaching a predetermined ΔV in the secondary battery cell 2 based on the -ΔV characteristic, evaluation of the charge/discharge state including any of deterioration diagnosis, failure prediction, and cycle life evaluation of the secondary battery cell 2 is performed. you can go Specifically, the evaluation means 12, for example, ΔO. D. A fitting curve may be drawn by applying an approximation function to the -ΔV characteristic to determine the probability. Also, the evaluation means 12 may, for example, calculate ΔO. D. The probability may be determined by performing Bayesian estimation on the -ΔV characteristic. Here, the evaluation means 12 is configured to evaluate that the secondary battery cell 2 corresponds to a predetermined state (for example, a deteriorated state or a failure state) when the probability exceeds a predetermined threshold. good.

The evaluation means 12 determines the ΔO. D. The evaluation may be performed based on a predictive model in which at least one of various parameters related to the -ΔV characteristic is used as an input value. The predictive model may be, for example, a statistical model. Also, the prediction model may be, for example, a machine learning model such as a deep learning model, and there is no restriction on the presence or absence of training data.

“Evaluation of cycle life” in the description of this specification refers to predicting, estimating, and quantifying the remaining number of times the secondary battery cell 2 can be charged/discharged (corresponding to the number of cycles).

As illustrated in FIG. 2, the BM flowchart in one embodiment of the present invention includes the following steps. First, the measuring means 11 measures the optical density in the area 200 of the secondary battery cell 2 . Next, the charge/discharge capacity of the secondary battery cell 2 is measured. Next, the evaluation means 12 selects the CO. D. Determine characteristics. Next, based on the measurement result by the measurement means 11, the evaluation means 12 determines the CO. D. Determine the cycle characteristics of the characteristic. Next, the evaluation means 12 calculates ΔO.D based on the cycle characteristics. D. to decide. Finally, the evaluation means 12 determine the ΔO. D. ΔV is determined based on and the charge/discharge state of the secondary battery cell 2 is evaluated.

As illustrated in FIG. 3, the region 200 of Embodiment 1 includes at least a portion of each of the active material/current collector 21/electrolyte 23 . In addition, the region 200 may further include at least part of each of the members constituting the secondary battery, such as a binder, a separator, a conductive aid, and a solid electrolyte interface (SEI) layer. Further, the region 200 of Embodiment 1 may take a mode that includes either the positive electrode active material 22 or the negative electrode active material 24 as the active material.

<<Embodiment 2>>
This specification describes Embodiment 2 of the present invention below. This specification omits the description of the configuration common to the other embodiments, and applies the same reference numerals to the second embodiment.

As illustrated in FIG. 4 , the region 200 of Embodiment 2 includes portions of each of the positive electrode-side current collector 21 and the positive electrode active material 22 . Here, the secondary battery cell 2 has voids 25 . The void 25 of Embodiment 2 may be provided in a part of the secondary battery cell 2 .

Region 200 of Embodiment 2 may include a portion of cathode active material 22, as an example. The region 200 of Embodiment 2 can have a configuration including a part of each of at least one of the current collector 21 , the positive electrode active material 22 , the electrolyte 23 , and the negative electrode active material 24 .

When the region 200 contains either the positive electrode active material 22 or the negative electrode active material 24 but does not contain the electrolyte 23 , the evaluation means 12 of the second embodiment evaluates the guest cations of the active material contained in the region 200 based on the optical density of the region 200 . The amount of M ⁺ (eg, Li ⁺ ) is evaluated, and based on that amount, the amount of charge in the active material is evaluated. At this time, the evaluation unit 12 evaluates the charge amount further based on the optical properties of the active material, as an example.

The evaluation means 12 of Embodiment 2 may be configured to determine the charge/discharge capacity based on the charge amount of the active material in the region 200 and evaluate the charge/discharge state of the secondary battery cell 2 .

<<Embodiment 3>>
This specification describes Embodiment 3 of the present invention below. This specification omits the description of the configuration common to the other embodiments, and applies the same reference numerals to the third embodiment.

As illustrated in FIG. 5, region 200 of Embodiment 3 includes a portion of either positive electrode active material 22 or negative electrode active material 24 . The measuring means 11 of the third embodiment makes the measurement light 111c incident on the region 200 along the orthogonal direction Y orthogonal to the stacking direction X of the current collector 21 and the active material.

The evaluation means 12 of Embodiment 3 evaluates the charge amount of the active material contained in the region 200 based on the optical density of the region 200 . At this time, the evaluation unit 12 evaluates the charge amount further based on the optical properties of the active material, as an example.

The evaluation means 12 of Embodiment 3 may be configured to determine the charge/discharge capacity based on the charge amount of the active material in the region 200 and evaluate the charge/discharge state of the secondary battery cell 2 .

<<Embodiment 4>>
This specification describes Embodiment 4 of the present invention below. This specification omits the description of the configuration common to the other embodiments, and applies the same reference numerals to the fourth embodiment.

As illustrated in FIG. 6 , region 200 of Embodiment 4 includes at least a portion of either positive electrode active material 22 or negative electrode active material 24 . The region 200 of Embodiment 2 can be configured to further include a portion of the current collector 21 and/or the electrolyte 23 .

The measuring means 11 of the fourth embodiment makes the measurement light 111c incident on the region 200 along the orthogonal direction Y orthogonal to the stacking direction X of the current collector 21 and the active material.

The spot diameter, alignment, etc. of the measurement light 111c in the fourth embodiment can be adjusted according to the number of types of secondary battery members included in the region 200 as the measurement target.

When the region 200 contains either the positive electrode active material 22 or the negative electrode active material 24 but does not contain the electrolyte 23, the evaluation means 12 of Embodiment 4 calculates the charge amount of the active material contained in the region 200 based on the optical density of the region 200. Evaluate. At this time, the evaluation unit 12 evaluates the charge amount further based on the optical properties of the active material, as an example.

The evaluation means 12 of Embodiment 4 may be configured to determine the charge/discharge capacity based on the charge amount of the active material in the region 200 and evaluate the charge/discharge state of the secondary battery cell 2 .

<<Embodiment 5>>
This specification describes Embodiment 5 of the present invention below. This specification omits the description of the configuration common to the other embodiments, and applies the same reference numerals to the fifth embodiment.

As illustrated in FIG. 7, in the optical characteristic measurement in the fifth embodiment, the optical characteristic measuring means 111 detects the scattered light generated when the area 200 is irradiated with the measurement light 111c from the light source 111a. To detect. At this time, the light receiving element 111b can measure the scattered light intensity of the scattered light. Note that the optical property measuring means 111 may be configured to further include a known or commonly used filter capable of removing Rayleigh scattered light.

Note that the optical characteristic measuring means 111 in Embodiment 5 may be configured to measure the transmitted light intensity in the region 200 in addition to the scattered light intensity in the region 200 .

The measuring means 11 in one embodiment of the present invention may be configured to measure the scattered light intensity instead of/in addition to the optical density of the region 200 . Further, the evaluation means 12 in one embodiment of the present invention may be configured to evaluate the charge/discharge state of the secondary battery cell 2 based on the scattered light intensity instead of/in addition to the optical density of the region 200 . Here, the optical characteristic measuring means 111 may be configured to include a light receiving element 111b for measuring transmitted light intensity and/or a light receiving element 111b for measuring scattered light intensity.

The measuring means 11 in one embodiment of the present invention may be configured to enter the measurement light 111c into the region 200 over the plurality of secondary battery cells 2 and measure the optical density of the region 200 .

The measuring means 11 in one embodiment of the present invention can adopt/select the wavelength of the measuring light 111c based on at least part of the optical properties of the material included in the region 200, for example.

The evaluation means 12 in one embodiment of the invention includes a known or customary computer 121 and a database 122 .

The computer 121 includes an arithmetic unit having a known or conventional processor capable of executing an instruction set, a main memory having a known or conventional volatile memory capable of storing the instruction set, and a known or conventional memory capable of recording programs and the like. It has at least an auxiliary storage device with media and a bus interface. It can be understood that the action and effect of the evaluation means 12 are realized by the processor. Also, the computer 121 may further include an input device, an output device, and a communication device.

The database 122 is a local storage (corresponding to an auxiliary storage device) that the computer 121 has, or an external storage capable of mutual communication with the computer 121 . Also, the database 122 can store the measurement parameters measured by the measuring means 11 . In addition, the database 122 stores various characteristics determined by the evaluation means 12 and/or charge/discharge states evaluated by the evaluation means 12 in the form of data 1200 .

The computer 121 in one embodiment of the present invention has means for measuring the secondary battery cell 2 in cooperation with the measuring means 11 . The means may be configured to control at least part of the measuring means 11, for example. Further, the means may be configured to synchronize the measurement by the optical property measuring means 111 and the measurement by the electrical property measuring means 112 . The control refers to, for example, control of alignment, scanning, etc. of the measurement light 111c. Further, the control refers to, for example, adjustment of charging/discharging current in measurement of charging/discharging characteristics.

It can be understood that various parameters, characteristics, etc. obtained by the measuring means 11 and/or the evaluating means 12 in one embodiment of the present invention can be used for control of the secondary battery cell 2 .

At least a part of the measurement means 11 and/or the evaluation means 12 in one embodiment of the present invention may be configured to use the secondary battery cell 2 as a power source.

At least part of the effects of the measurement means 11 and the evaluation means 12 in one embodiment of the present invention may be realized by a device group housed in the same housing. Also, the measuring means 11 and the evaluating means 12 may be packaged as the same system. Note that the housing/system may be configured to have the secondary battery cell 2 therein.

The negative electrode active material 24 in one embodiment of the present invention is preferably made of the transparent electrode material when the negative electrode active material 24 is included in the region 200 .

<<Example 1>>
This specification describes Example 1 of the present invention below. In this specification, descriptions of configurations common to the embodiments of the present invention are omitted for examples, and the same reference numerals are applied.

The secondary battery cell 2 in Example 1 consisted of a 400 nm-thick Nb ₂ O ₅ thin film (corresponding to the positive electrode active material 22) deposited on NESA glass (corresponding to the current collector 21) by a sputtering method. , a separator having voids (different from the voids 25), Li pieces (corresponding to the negative electrode active material 24), and Pyrex (registered trademark) glass are laminated along the stacking direction X. . The gap is filled with LiC104-PC (corresponding to the electrolyte 23), which is an electrolytic solution.

It can be understood that the Nb ₂ O ₅ thin film in Example 1 is a Li _x Nb ₂ O ₅ thin film in which the storage amount of the guest cation Li ⁺ changes with charging and discharging. Incidentally, the Nb ₂ O ₅ thin film in Example 1 was heat-treated under the condition of annealing time of 60 minutes after film formation.

It can be understood that the region 200 in Example 1 includes the current collector 21 , the positive electrode active material 22 , the electrolyte 23 , and the negative electrode active material 24 .

The measuring means 11 in Example 1 emits measuring light 111c from the light source 111a to the area 200 along the stacking direction X of the current collector 21 and the active material. In addition, the measurement means 11 measures the incident light intensity and the transmitted light intensity by receiving the measurement light 111c transmitted through the region 200 with a double beam spectrophotometer (corresponding to the light receiving element 111b), Make a density measurement. In addition, the measuring means 11 measures the charging/discharging characteristics of the secondary battery cell 2 under the conditions of an Ar atmosphere, a charging/discharging current of 10 μA, and an ambient temperature of 500°C.

As shown in FIG. 8, the optical properties of the secondary battery cell 2 (especially the Li _x Nb ₂ O ₅ thin film) in Example 1 exhibit the wavelength dependency of the optical density and the Li amount (x) dependency.

In the optical properties of Example 1, it can be understood that the optical density in the visible light region increases with an increase in the amount of Li (x) when x=0.0-1.0. In addition, in the optical characteristics, it can be understood that when x<1.0, the increase in optical density in the longer wavelength region tends to saturate compared to the visible light region. In addition, in the optical characteristics, when x>1.0, the optical density in the short wavelength side (eg, 400-500 nm wavelength band) compared to the visible light region tends to increase depending on the amount of Li (x). It can be grasped that it is in

In view of such optical characteristics, one embodiment of the present invention considers the dependence of the optical density of the active material constituting the secondary battery cell 2 on the guest cation M ⁺ amount, etc., and the region 200 containing the active material It can be understood that the BM technology capable of evaluating the charge/discharge state is provided.

The cycle characteristics of FIGS. 9 and 10 correspond to the charge/discharge characteristics of the secondary battery cell 2 in Example 1 and the CO of the secondary battery cell 2 in Example 1, respectively. D. characterize. Note that "1, 2, 5" in the figure indicate the number of cycles. 9 and 10, the charge/discharge characteristics and CO. D. It can be understood that each of the characteristics corresponds in terms of the increase or decrease of the vertical axis parameter in each characteristic.

As shown in FIG. 11, the ΔO. D. According to the -ΔV characteristic, ΔO. D. It can be understood that (the amount of change in optical density in cycle characteristics) and ΔV (the amount of voltage drop in cycle characteristics) have a positive correlation. Note that ΔO. D. It can be understood that the rapid increase at the beginning and end of the curve in the -ΔV characteristic is due to the polarization of the active material and not due to the migration of the guest cation Li ^{2 +} .

In view of such characteristics, one embodiment of the present invention includes deterioration diagnosis, failure prediction, etc. of the secondary battery cell 2 based on the optical density of the region 200 containing the active material constituting the secondary battery cell 2. It can be understood that the BM technology that enables evaluation of the charge/discharge state is provided.

<<Example 2>>
This specification describes Example 2 of the present invention below. In this specification, descriptions of configurations common to the embodiments and examples of the present invention are omitted, and the same reference numerals are applied to the examples.

The secondary battery cell 2 in Example 2 uses a V ₂ O ₅ thin film as the positive electrode active material 22 instead of the Nb ₂ O ₅ thin film. Further, it can be understood that the V ₂ O ₅ thin film in Example 1 is a Li _x V ₂ O ₅ thin film in which the storage amount of the guest cation Li ⁺ changes with charging and discharging. The V ₂ O ₅ thin film is formed by the same method as in Example 1 or by a method corresponding to Example 1. FIG.

As shown in FIG. 12, the optical characteristics of the secondary battery cell 2 (in particular, the Li _x V ₂ O ₅ thin film) in Example 2 exhibit the wavelength dependence and the Li amount (x) dependence of the optical coefficient.

As for the optical characteristics of the positive electrode active material 22 in Example 2, it can be understood that the tendency of the optical density to increase or decrease with an increase in the amount of Li (x) varies depending on the wavelength band.

In the optical properties of the positive electrode active material 22 in Example 2, for example, it can be understood that there is a tendency for the optical density to increase due to the formation of colored centers due to the increase in the amount of Li (x) in the wavelength band of ≧500 nm. . However, in the optical properties, there is a tendency for the optical density to decrease due to the shift of the fundamental absorption edge to the short wavelength side due to the increase in the amount of Li (x) in the wavelength band of ≤ 500 nm (including the ultraviolet wavelength band). can be understood. It can be understood that the colored center corresponds to a tungsten bronze-like point-defect colored center and contributes to the formation of a broad absorption band in the visible light region. The fundamental absorption edge corresponds to the rise of the short wavelength region in the optical characteristics.

In view of such optical characteristics, one embodiment of the present invention considers the wavelength selectivity and cycle number dependence of the optical density of the active material that constitutes the secondary battery cell 2. The active material-containing region 200 It can be understood that the BM technology that can evaluate the charge and discharge state of the battery is provided.

According to the present invention, it is possible to provide a novel electro-optical fusion type BM technology.

Moreover, according to the present invention, it is possible to provide a novel BM technique that enables simple evaluation of the charge/discharge state of a secondary battery.

Moreover, according to the present invention, it is possible to provide a novel BM technology that enables non-invasive, non-contact, and non-destructive evaluation of the charge/discharge state of a secondary battery.

Further, according to the present invention, it is possible to provide a novel BM technique that enables real-time evaluation of the charge/discharge state of a secondary battery.

1: BM system 2: Secondary battery cell 11: Measuring means 12: Evaluation means 21: Current collector 22: Positive electrode active material 23: Electrolyte 24: Negative electrode active material 25: Gap 111: Optical characteristic measuring means 111a: Light source 111b: Light receiving element 111c: light for measurement 112: electrical property measuring means 121: computer 122: database 200: region X: stacking direction Y: orthogonal direction

Claims (12)

measuring means for measuring optical density in a region containing at least part of an active material constituting a secondary battery cell;
determining cycle characteristics of charge/discharge capacity-optical density characteristics (COD characteristics) based at least on the optical density;
Optical density change amount corresponding to the difference between the optical density exhibiting a predetermined charge-discharge capacity at the cycle number = 1 and the optical density exhibiting the predetermined charge-discharge capacity at the cycle number ≥ 2 determined as the cycle characteristic The number of cycles determined-ΔO. D. and evaluation means for evaluating the charge/discharge state of the secondary battery cell based on the gradient in the characteristics . 2. The battery management system according to claim 1, wherein said evaluation means evaluates said secondary battery cell as corresponding to a predetermined charge/discharge state when said gradient exceeds a predetermined threshold. performing operand measurements of the optical density and the charge/discharge capacity of the secondary battery cell;
Based on the optical density and the charge/discharge capacity of the secondary battery cell for different numbers of cycles, the CO. D. determine the cycle characteristics of the characteristic,
The measuring means measures the optical density of the secondary battery cell to be evaluated,
wherein the evaluation means determines the cycle characteristics based on the optical density;
The battery management system according to claim 1 or 2. The region includes at least part of the positive electrode active material that is the active material
The battery management system according to any one of claims 1 to 3 . The region includes at least part of a negative electrode active material that is the active material
The battery management system according to any one of claims 1 to 4 . The region further includes at least part of a current collector that constitutes the secondary battery cell.
The battery management system according to any one of claims 1-5 . The region further includes at least part of an electrolyte that constitutes the secondary battery cell.
The battery management system according to any one of claims 1-6 . The measuring means measures the optical density by receiving the measuring light that is incident on the region and transmitted through the region.
The battery management system according to any one of claims 1-7 . The measurement light is at least one single-wavelength light selected from visible light, ultraviolet light, and infrared light
The battery management system according to claim 8 . The evaluation means evaluates the CO based on the optical density and the charge/discharge capacity of the secondary battery cell for different numbers of cycles. D. Determine the cycle characteristics of the characteristic; ΔO. D. -ΔV characteristics and the CO. D. 4. The battery management system according to claim 3 , wherein the amount of voltage drop ([Delta]V) of the secondary battery cell is evaluated based on the amount of optical density change ([Delta]O.D.) in the cycle characteristic of the characteristic. The evaluation means evaluates the amount of charge in the active material based on the optical density.
The battery management system according to any one of claims 1-10 . a measuring step of measuring the optical density in a region containing at least part of the active material constituting the secondary battery cell;
determining cycle characteristics of charge/discharge capacity-optical density characteristics (COD characteristics) based at least on the optical density;
Optical density change amount corresponding to the difference between the optical density exhibiting a predetermined charge-discharge capacity at the cycle number = 1 and the optical density exhibiting the predetermined charge-discharge capacity at the cycle number ≥ 2 determined as the cycle characteristic The number of cycles determined-ΔO. D. and an evaluation step of evaluating the charge/discharge state of the secondary battery cell based on the gradient in the characteristic .

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