Device and method for detecting state of inside of battery

Abstract

To provide a device and a method for detecting the inside of a battery which can accurately detect the state of the inside of a battery while suppressing increase of the weight and the volume of the battery.SOLUTION: A battery inside state detector 100 is for detecting the state of the inside of a battery 200 having a laminate structure of an electrode mixture layer 24 containing an electrode active material and a collector 23. The detector includes: a first AE sensor 11 for detecting a first AE signal of an electrode terminal part electrically connected to the collector 23; a second AE sensor 12 for detecting a second AE signal of a member which is not the electrode terminal part; and an analyzer 10 for detecting the state of the inside of the battery 200 on the basis of the differential signal of the first AE signal and the second AE signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a device and a method for detecting the internal state of a battery. [Background technology]

[0002] Patent document 1 describes an internal state detection device that detects elastic waves generated within a battery using an AE (Acoustic Emission) sensor installed on the outside of the battery and detects the internal state of the battery by analyzing the detected elastic waves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 001471 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when detecting the internal state of a battery using the internal state detection device of Patent Document 1, it is necessary to attach an elastic film and a non-metallic plate to the outside of the battery in order to improve the detection accuracy of the elastic waves generated inside the battery, which may increase the weight and volume of the battery.

[0005] An object of the present invention is to provide an apparatus and method for detecting the internal state of a battery that can accurately detect the internal state of a battery while suppressing an increase in the weight and volume of the battery. [Means for solving the problem]

[0006] The present invention solves the above problem by using a first AE sensor to detect a first AE signal of an electrode terminal electrically connected to a current collector of a storage element, and using a second AE sensor to detect a second AE signal of a member other than the electrode terminal, and detecting the internal state of the battery based on a differential signal between the first AE signal and the second AE signal. Effect of the Invention

[0007] The present invention has the effect of being able to detect the internal state of the battery with high accuracy while suppressing increases in the weight and volume of the battery. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are a cross-sectional view of a battery and a diagram showing the configuration of a battery internal state detection device that detects the internal state of the battery. [Diagram 2] 13 is a diagram showing another example of the attachment location of the first AE sensor of the battery internal state detection device. FIG. [Diagram 3] 4 is a graph showing an example of a first AE signal, a second AE signal, and a differential signal acquired by a battery internal state detection device. [Figure 4] 4 is a flowchart showing the steps of a battery internal state detection method executed by a battery internal state detection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First Embodiment As shown in FIG. 1, the battery internal state detection device 100 according to the present embodiment detects the internal state of a battery 200. The battery internal state detection device 100 includes an analysis device 10, a first AE sensor 11, a second AE sensor 12, and an output device 13. The analysis device 10 is connected to the first AE sensor 11 and the second AE sensor 12 by wire or wirelessly. The first AE sensor 11 and the second AE sensor 12 are attached to the battery 200. The first AE sensor 11 and the second AE sensor 12 detect elastic waves of 10 kHz to 1 MHz. In the example shown in FIG. 1, two first AE sensors 11 and one second AE sensor 12 are provided, but this is not limited thereto, and one or three or more first AE sensors 11 may be provided, and a plurality of second AE sensors 12 may be provided. The output device 13 is also connected to the analysis device 10 by wire or wirelessly. The output device 13 is, for example, a display, an audio output device, or a printer.

[0010] As shown in FIG. 1, the battery 200 has an electricity storage element 21 sealed inside a battery exterior part 22 such as a laminate film. The electricity storage element 21 has a laminated structure of a current collector 23 and an electrode mixture layer 24 containing an electrode active material. Specifically, in the example shown in FIG. 1, the electricity storage element 21 has a plurality of negative electrodes 25 and a plurality of positive electrodes 26 arranged alternately along the lamination direction L. The negative electrode 25 has a negative electrode side current collector 23a and a negative electrode side electrode mixture layer 24a provided on both sides or one side of the negative electrode side current collector 23a. The positive electrode 26 has a positive electrode side current collector 23b and a positive electrode side electrode mixture layer 24b provided on both sides or one side of the positive electrode side current collector 23b. That is, the current collectors 23 (the negative electrode side current collector 23a and the positive electrode side current collector 23b) and the electrode mixture layer 24 (the negative electrode side electrode mixture layer 24a and the positive electrode side electrode mixture layer 24b) are stacked along the stacking direction L.

[0011] A negative electrode side tab lead 29a connected to the negative electrode side current collector 23a and a positive electrode side tab lead 29b connected to the positive electrode side current collector 23b are led out from the battery exterior part 22 of the battery 200. The tab leads 29 (negative electrode side tab lead 29a and positive electrode side tab lead 29b) constitute an electrode terminal part electrically connected to the current collector 23. A first AE sensor 11 is attached to each of the negative electrode side tab lead 29a and the positive electrode side tab lead 29b. Note that the first AE sensor 11 may be attached to only one of the negative electrode side tab lead 29a and the positive electrode side tab lead 29b.

[0012] Further, the attachment location of the first AE sensor 11 is not limited to the tab lead 29. For example, as shown in Fig. 2, the first AE sensor 11 may be provided on a bus bar 30 that connects a plurality of batteries 200 together. The bus bar 30, like the tab lead 29, constitutes an electrode terminal portion that is electrically connected to the current collector 23. Further, the first AE sensor 11 may be provided on an electronically conductive member that is electrically connected to the electrode terminal portion (the tab lead 29 or the bus bar 30).

[0013] 1 and 2, a second AE sensor 12 is attached to the outside of the battery exterior part 22. The battery exterior part 22 is made of an insulating material and is electrically insulated from the negative electrode side tab lead 29a and the positive electrode side tab lead 29b, which are electrode terminal parts. The second AE sensor 12 may be attached to a part that comes into contact with the battery exterior part 22.

[0014] As shown in FIG. 3, the analysis device 10 acquires a first AE signal detected by the first AE sensor 11 and a second AE signal detected by the second AE sensor 12. The analysis device 10 then acquires a differential signal between the first AE signal and the second AE signal. Here, the first AE signal includes noise outside the battery 200 in addition to a signal indicating an elastic wave generated inside the battery 200. On the other hand, the second AE signal is a signal mainly indicating noise outside the battery 200. Therefore, the differential signal between the first AE signal and the second AE signal is a signal in which the influence of noise outside the battery 200 is cancelled, and is an AE signal mainly indicating only elastic waves generated inside the battery 200. In addition, when a plurality of first AE sensors 11 are attached to the battery 200, the analysis device 10 may average the signals acquired from each of the plurality of first AE sensors 11 to calculate the first AE signal, or may acquire a plurality of differential signals based on the plurality of first AE signals. Similarly, in the case where multiple second AE sensors 12 are attached to the battery 200, the analysis device 10 may calculate a second AE signal by averaging the signals acquired from each of the multiple second AE sensors 12, or may acquire multiple differential signals based on the multiple second AE signals.

[0015] The analysis device 10 determines that an abnormality has occurred inside the battery 200 when the number of AE events of the differential signal exceeds a predetermined threshold number. The analysis device 10 also determines that an abnormality has occurred inside the battery 200 when the AE event intensity of the differential signal exceeds a predetermined threshold intensity. The abnormality inside the battery 200 refers to gas generation or active material cracking in the electrode mixture layer 24 of the battery 200. The number of AE events is the number of AE signals generated due to gas generation or active material cracking in the battery 200, and is specifically the number of waves in the waveform graph shown in FIG. 3. The AE event intensity is the intensity of the AE signal generated due to gas generation or active material cracking in the battery 200, and is specifically the amplitude of the waveform graph shown in FIG. 3. In the example shown in FIG. 3, the threshold intensity of the AE event intensity is X. That is, the analysis device 10 determines that an abnormality has occurred inside the battery 200 when the value of the AE signal exceeds X or when the value of the AE signal falls below -X.

[0016] When the analysis device 10 determines that an abnormality has occurred inside the battery 200, the analysis device 10 outputs to the output device 13 a signal indicating that an abnormality has occurred inside the battery 200. The analysis device 10 may also output information including the number of AE events and the intensity of the AE events to the output device 13. The analysis device 10 may also output to the output device 13 a waveform graph of a differential signal between the first AE signal and the second AE signal.

[0017] Next, a procedure for detecting the internal state of a battery executed by the battery internal state detection device 100 will be described with reference to the flowchart of FIG. First, in step S1 , the analysis device 10 of the battery internal state detection device 100 acquires the first AE signal detected by the first AE sensor 11 . Furthermore, in step S2, the analytical device 10 acquires the second AE signal detected by the second AE sensor 12. The process of step S1 and the process of step S2 are executed almost simultaneously.

[0018] Next, in step S3, the analysis device 10 obtains a differential signal between the first AE signal and the second AE signal.

[0019] Then, in step S4, the analyzer 10 determines whether the number of AE events in the difference signal exceeds a predetermined threshold number. If it is determined in step S4 that "the number of AE events exceeds the threshold number", then in step S6, the analyzer 10 determines that an abnormality has occurred in the battery 200.

[0020] On the other hand, if it is determined in step S4 that "the number of AE events is equal to or less than the threshold number", then in step S5, the analyzer 10 determines whether the AE event intensity of the differential signal exceeds a predetermined threshold intensity. If it is determined in step S5 that "the AE event intensity exceeds the threshold intensity", the analyzer 10 determines in step S6 that an abnormality has occurred in the battery 200. On the other hand, if it is determined in step S5 that "the AE event intensity is equal to or less than the threshold intensity", the analyzer 10 determines in step S7 that no abnormality has occurred in the battery 200.

[0021] Furthermore, in step S8, the analysis device 10 outputs to the output device 13 the determination result in step S6 or step S7.

[0022] The analysis device 10 may omit step S4 and determine the presence or absence of an abnormality in the battery 200 only by the determination process of "whether or not the AE event intensity of the differential signal exceeds a predetermined threshold intensity" in step S5. The analysis device 10 may omit step S5 and determine the presence or absence of an abnormality in the battery 200 only by the determination process of "whether or not the number of AE events of the differential signal exceeds a predetermined threshold number" in step S4. The analysis device 10 may execute the determination process of step S4 after the determination process of step S5.

[0023] As described above, the battery internal state detection device 100 according to this embodiment includes a first AE sensor 11 that detects a first AE signal of an electrode terminal portion electrically connected to a current collector 23 of the battery 200, a second AE sensor 12 that detects a second AE signal of a member other than the electrode terminal portion, and an analyzer 10 that detects the internal state of the battery based on a differential signal between the first AE signal and the second AE signal. The differential signal acquired by the battery internal state detection device 100 is an AE signal in which the influence of noise outside the battery 200 is cancelled and which indicates only an elastic wave generated inside the battery 200, so that the battery internal state detection device 100 can detect the internal state of the battery 200 with high accuracy based on the differential signal. Therefore, the battery internal state detection device 100 can accurately detect the internal state of the battery 200 by including the first AE sensor 11 that detects the first AE signal of the electrode terminal portion and the second AE sensor 12 that detects the second AE signal of a member other than the electrode terminal portion, and therefore does not need to provide members such as an elastic film and a nonmetallic plate on the outside of the battery. This allows the battery internal state detection device 100 to detect the internal state of the battery 200 with high accuracy while suppressing an increase in the weight and volume of the battery 200.

[0024] The first AE sensor 11 of the battery internal state detection device 100 is provided on the tab lead 29 or bus bar 30 as the electrode terminal of the battery 200, or on an electronically conductive member electrically connected to the electrode terminal. As a result, the elastic waves generated inside the battery 200 are transmitted to the first AE sensor 11 via a member made of a material with low acoustic impedance, such as a current collector foil (e.g., copper or aluminum), so that attenuation of the elastic waves is suppressed and the first AE sensor 11 can detect the first AE signal with higher sensitivity. If the first AE sensor 11 is provided on the battery exterior 22 of the battery 200, the elastic waves will attenuate because they pass through the power storage element 21 and the battery exterior 22 before being transmitted to the first AE sensor 11. However, if the first AE sensor 11 is provided on the electrode terminal or an electronically conductive member electrically connected to the electrode terminal as in the present invention, the number of members through which the elastic waves pass is reduced, and attenuation of the elastic waves can be suppressed.

[0025] Furthermore, the second AE sensor 12 of the battery internal state detection device 100 is provided on the battery exterior part 22 that is electrically insulated from the electrode terminal part, or on a component that contacts the battery exterior part 22. This makes it difficult for the elastic waves inside the battery 200 to be transmitted to the second AE sensor 12, and the proportion of noise contained in the second AE signal increases. Therefore, in the differential signal, the influence of noise outside the battery 200 is sufficiently suppressed, and the proportion of the AE signal that indicates only the elastic waves generated inside the battery 200 increases, so that the battery internal state detection device 100 can accurately detect the internal state of the battery 200.

[0026] Furthermore, the analysis device 10 of the battery internal state detection device 100 determines that an abnormality has occurred inside the battery when the number of AE events of the differential signal exceeds a predetermined threshold number. This enables the battery internal state detection device 100 to quantitatively grasp the number of occurrences of abnormal phenomena that have occurred inside the battery 200 and detect an abnormality in the battery 200.

[0027] Moreover, the analysis device 10 of the battery internal state detection device 100 determines that an abnormality has occurred inside the battery 200 when the AE event intensity of the differential signal exceeds a predetermined threshold intensity. As a result, even if the number of AE events of the differential signal is small, the battery internal state detection device 100 can detect the occurrence of an abnormality inside the battery 200 when it detects a high AE event intensity. Specifically, among the main phenomena caused by the deterioration of the battery 200, the occurrence of cracks in the active material tends to cause a smaller number of AE events but a higher AE event intensity than gas generation. On the other hand, the influence of cracks in the active material on the deterioration of battery performance is greater than that of gas generation. Therefore, the battery internal state detection device 100 can more accurately grasp the deterioration state of the battery 200 by detecting the occurrence of a high-intensity AE event.

[0028] Moreover, the first AE sensor 11 and the second AE sensor 12 of the battery internal state detection device 100 detect elastic waves of 10 kHz to 1 MHz. This allows the battery internal state detection device 100 to selectively detect AE signals caused by abnormal phenomena occurring inside the battery 200, and to accurately detect abnormalities inside the battery 200. [Explanation of symbols]

[0029] 100... Battery internal state detection device 10…Analyzer 11…First AE sensor 12…Second AE sensor 22…Battery exterior part 23...Current collector 24...Electrode mixture layer 29...Tab lead (electrode terminal part) 30... Bus bar (electrode terminal part)

Claims

1. A battery internal state detection device for detecting an internal state of a battery having a laminated structure of an electrode mixture layer containing an electrode active material and a current collector, a first AE sensor for detecting a first AE signal of an electrode terminal portion electrically connected to the current collector; a second AE sensor for detecting a second AE signal of a member other than the electrode terminal portion; an analyzer that detects the internal state of the battery based on a differential signal between the first AE signal and the second AE signal.

2. 2 . The battery internal state detection device according to claim 1 , wherein the first AE sensor is provided on a tab lead or a bus bar serving as the electrode terminal portion, or on an electronically conductive member electrically connected to the electrode terminal portion.

3. 2 . The battery internal state detection device according to claim 1 , wherein the second AE sensor is provided on a battery exterior portion that is electrically insulated from the electrode terminal portion, or on a component that contacts the battery exterior portion.

4. 2 . The battery internal state detection device according to claim 1 , wherein the analysis device determines that an abnormality has occurred inside the battery when the number of AE events of the differential signal exceeds a predetermined threshold number.

5. 2 . The battery internal state detection device according to claim 1 , wherein the analysis device determines that an abnormality has occurred inside the battery when an AE event intensity of the differential signal exceeds a predetermined threshold intensity.

6. 2. The battery internal state detection device according to claim 1, wherein the first AE sensor and the second AE sensor detect elastic waves of 10 kHz to 1 MHz.

7. A method for detecting an internal state of a battery, comprising the steps of: detecting an internal state of a battery having a laminated structure of an electrode mixture layer containing an electrode active material and a current collector, using a device for detecting an internal state of the battery, the method comprising the steps of: The battery internal state detection device includes: Detecting a first AE signal from an electrode terminal portion electrically connected to the current collector; A second AE signal of a member other than the electrode terminal portion is detected. The internal state of the battery is detected based on a differential signal between the first AE signal and the second AE signal.

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