In-situ battery failure analysis system and method

Abstract

Disclosed in the present invention are an in-situ battery failure analysis system and method, which are applicable to a rechargeable battery preset with an optical fiber probe. The in-situ battery failure analysis system comprises: a battery model, a charging and discharging test system, an optical fiber stress test system and a differential electrochemical mass spectrometry test system, wherein by means of the battery model, a rechargeable battery to be analyzed and an optical fiber probe thereof are respectively coupled to the optical fiber stress test system and the differential electrochemical mass spectrometry test system, such that when the charging and discharging test system performs charging and discharging on the rechargeable battery, the following operations can be synchronously implemented: the optical fiber stress test system performs a test to obtain a stress change feature of an electrode material of the rechargeable battery during charging, and the differential electrochemical mass spectrometry test system performs a test to obtain a gas generation characteristic of the electrode material of the rechargeable battery during charging. Thus, by means of the stress change feature and the gas generation characteristic, a failure mechanism of the electrode material of the rechargeable battery during charging is clarified.

Description

Battery in-situ failure analysis system and method TECHNICAL FIELD

[0001] The present application relates to the failure analysis of rechargeable lithium-ion batteries, in particular to a battery in-situ failure analysis system and method. BACKGROUND

[0002] Rechargeable lithium-ion batteries are widely used in consumer electronics, power grids, aerospace and electric vehicles due to their excellent performance in energy density, economy and environmental footprint. However, frequent problems such as lithium battery fires, explosions, gas leaks, poor durability, etc. have caused serious problems to people's lives. At present, battery management systems (BMS) are mainly used to monitor battery data and adjust charging and discharging strategies, or in-situ X-ray diffractometer, operable electron microscope and other means are used to track the volume and stress changes caused by lithium deintercalation in the electrode. The sensors of these technologies are often placed outside the battery and cannot monitor the local stress changes occurring in the electrode in real time. In addition, the battery is prone to produce gas during long cycle, overcharge, overdischarge or thermal abuse, resulting in performance deterioration. In order to solve the above problems, it is urgent to develop local and non-invasive operation technology combined with specific battery design to realize the detection of stress change characteristics and gas production characteristics of the battery internal interface under real charging and discharging conditions. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a battery in-situ failure analysis system and method.

[0004] To solve the above technical problems, the technical solution adopted by the present application is as follows:

[0005] A battery in-situ failure analysis system, characterized in that: it is suitable for a rechargeable battery with an optical fiber probe arranged inside, and the optical fiber probe is in contact with at least one of the positive electrode sheet, the electrolyte and the negative electrode sheet of the rechargeable battery, and the two ends of the optical fiber probe are exposed outside the rechargeable battery; wherein the rechargeable battery can be a lithium-ion battery, a solid-state battery, a semi-solid-state battery, a sodium-ion battery, a water-based zinc-ion battery, a lithium metal battery or a battery with the same structure.

[0006] The battery in-situ failure analysis system comprises a battery model, a charging and discharging test system, an optical fiber stress test system and a differential electrochemical mass spectrometry test system.

[0007] The battery model has a battery model shell provided with a positive electrode terminal, a negative electrode terminal, an air inlet channel, an air outlet channel and a model sealed internal cavity, wherein the air inlet channel and the air outlet channel are respectively communicated with the model sealed internal cavity; and when the rechargeable battery is installed into the battery model, the rechargeable battery is fixed in the model sealed internal cavity, and the positive electrode terminal and the negative electrode terminal are respectively electrically connected with the tab on the positive electrode plate and the negative electrode plate of the rechargeable battery.

[0008] The charge-discharge test system can charge and discharge the rechargeable battery installed in the battery model through the positive electrode terminal and the negative electrode terminal according to a preset charge-discharge program; wherein the charge-discharge program can be constant current charge-discharge, constant voltage charge-discharge, constant power charge-discharge, etc., and the constant current charge-discharge current can be selected as C / 5, C / 10, C / 15, C / 20, C / 30, etc.

[0009] The optical fiber stress test system can guide the input light into the optical fiber probe and detect the output light transmitted through the optical fiber probe to obtain the stress change characteristics of the electrode material of the rechargeable battery during the charging process.

[0010] The differential electrochemical mass spectrometry test system can inject inert gas into the model sealed internal cavity through the air inlet channel and detect the gas output from the air outlet channel to obtain the gas production characteristics of the electrode material of the rechargeable battery during the charging process; wherein the inert gas can be argon, helium, neon, etc., and the gas purity is 99.999%.

[0011] Preferably, the optical fiber probe is arranged at the junction position of the positive electrode plate and the electrolyte, or at the junction position of the negative electrode plate and the electrolyte.

[0012] Preferably, the battery model shell is composed of a positive electrode side top cover provided with the positive electrode terminal and a negative electrode side base provided with the negative electrode terminal, and the positive electrode side top cover and the negative electrode side base combine to form the model sealed internal cavity. The via hole on the battery model shell can be sealed by coating epoxy resin.

[0013] Wherein:

[0014] The optical fiber probe can be any one of a fiber with a grating, a cavity fiber, a micro fiber, a nano fiber, a tapered fiber, a side-polished fiber, a microstructure fiber and a photonic crystal fiber; the grating type of the fiber with a grating can be any one of a fiber Bragg grating (FBG), a tilted fiber Bragg grating (TFBG), a long period fiber grating (LPG), a chirped fiber grating and a phase-shifted grating.

[0015] The optical fiber probe preferably consists of a fiber core and a cladding which are sequentially sleeved from inside to outside, and an inclined grating is arranged on the fiber core, and the inclination angle of the inclined grating relative to the longitudinal axis of the fiber core is less than 90 degrees. Preferably, the inclination angle of the inclined grating ranges from 2 degrees to 45 degrees. Further, the optical fiber probe preferably further comprises a surface plasmon resonance layer (i.e. SPR layer) coated on the outer surface of the cladding, wherein the SPR layer is a material capable of exciting surface plasmon resonance (SPR), and the material of the SPR layer can be any one of gold (Au), silver (Ag), platinum (Pt), copper (Cu), aluminum (Al), semiconductor material, metal oxide material, two-dimensional (2D) material, and optical super material. Further, the optical fiber probe preferably further comprises a protective film layer coated on the outer surface of the surface plasmon resonance layer (i.e. SPR layer), and the material of the protective film layer can be diamond, silicon, indium tin oxide (ITO), zinc peroxide (ZnO2), tin oxide (SnO2), indium oxide (In2O3), polyethylene (PE), or polypropylene (PP). Further, the optical fiber probe preferably further comprises a transition film layer arranged between the cladding and the surface plasmon resonance layer (i.e. SPR layer), and the transition film layer is used to improve the adhesion of the cladding to the fiber core, wherein the transition film layer can be any one of chromium (Cr), titanium (Ti), or molybdenum (Mo).

[0016] The working mode of the optical fiber probe can be transmission mode or reflection mode.

[0017] When designed as transmission mode, the light source device guides the input light from one end of the optical fiber probe, and the other end of the optical fiber probe guides the output light and inputs it to the signal detection and processing device.

[0018] When designed as reflection mode, the light source device and the signal detection and processing device are arranged at the same end of the optical fiber probe, and a mirror is arranged at the other end of the optical fiber probe, so that the input light guided by the light source device is transmitted forward through the optical fiber probe, reflected by the mirror, transmitted backward through the optical fiber probe, and then output to the signal detection and processing device. Further, in this mode, the system can further comprise a fiber circulator, which is arranged between the light source device and the optical fiber probe along the input light path, and arranged between the optical fiber probe and the signal detection and processing device along the output light path. The fiber circulator separates the input light path and the output light path, so that the signal detection and processing device can be free from the influence of the input light, and further obtain the signal of the cladding mode or SPR from the optical fiber probe.

[0019] The optical fiber probe can be configured as a single point, or can be configured as multiple points through series and parallel connection.

[0020] As a preferred embodiment of the present application: referring to FIG. 2, the optical fiber probe is composed of an optical fiber core, a cladding and a surface plasmon resonance layer (i.e. SPR layer) which are sequentially sleeved from inside to outside, and the optical fiber core is provided with an inclined fiber tilted Bragg grating (i.e. FTBG); thus, the stress change characteristics of the electrode material of the rechargeable battery during the charging process can be calculated by Formulas 1 to 4.

[0021] Moreover, the optical fiber stress testing system comprises a light source device capable of guiding input light into the optical fiber probe, and a signal detection and processing device capable of receiving output light transmitted by the optical fiber probe and converting the output light into an electrical signal for detection, so as to obtain the stress change characteristics of the electrode material of the rechargeable battery during the charging process. The light source device can be a broadband light source or a tunable laser source, and the signal detection and processing device can adopt a spectrum analyzer, or can adopt an optical detector and an analog-to-digital converter to receive the output light transmitted by the optical fiber probe with the optical detector and convert the analog electrical signal into a digital electrical signal with the analog-to-digital converter.

[0022] As a preferred embodiment of the present application: referring to FIG. 3, the differential electrochemical mass spectrometry testing system comprises: the gas outlet channel is connected to the inlet of the differential electrochemical mass spectrometer through a vacuum system pipeline, and the vacuum system pipeline is sequentially provided with a water-blocking and air-permeable membrane, a gas coarse adjustment valve, a mechanical pump, a gas fine adjustment valve and a turbo pump in the direction from the gas outlet channel to the differential electrochemical mass spectrometer, so that the gas output from the gas outlet channel enters the differential electrochemical mass spectrometer through the pipeline for detection, and the detection data output by the differential electrochemical mass spectrometer is analyzed by data analysis software to obtain the gas production characteristics of the electrode material of the rechargeable battery during the charging process.

[0023] A battery in-situ failure analysis method, characterized in that: based on the battery in-situ failure analysis system, comprising:

[0024] Step S1, installing the rechargeable battery to be analyzed into the battery model, and completing the connection between the battery model and the charge-discharge testing system, the optical fiber stress testing system and the differential electrochemical mass spectrometry testing system;

[0025] Step S2, injecting inert gas into the model sealed inner cavity through the gas inlet channel with the differential electrochemical mass spectrometry testing system, so that the air in the model sealed inner cavity is discharged through the gas outlet channel, i.e. the model sealed inner cavity is filled with the injected inert gas;

[0026] Step S3, performing charge-discharge test on the rechargeable battery installed in the battery model with the charge-discharge testing system;

[0027] Step S4, guiding the input light into the optical fiber probe by the optical fiber stress testing system, and detecting the output light transmitted by the optical fiber probe, so as to obtain the stress change characteristics of the electrode material of the rechargeable battery during the charging process according to the output light; thus, it can be judged whether there is an abnormal situation in the rechargeable battery, such as electrolyte aging, lithium dendrite growth, electrode material lattice structure damage, etc., and the failure mechanism of the electrode material during the charging process is clarified.

[0028] Step S5, detecting the gas output from the gas outlet by the differential electrochemical mass spectrometry testing system, so as to obtain the gas production characteristics of the electrode material of the rechargeable battery during the charging process; thus, the influence of the cycle life shortening, electrolyte decomposition, and polarization increase of the rechargeable battery can be judged by the gas production characteristics, and the failure mechanism of the electrode material during the charging process is clarified.

[0029] Therefore, the rechargeable battery and its optical fiber probe to be analyzed are respectively coupled with the optical fiber stress testing system and the differential electrochemical mass spectrometry testing system by the battery model, so that when the rechargeable battery is charged and discharged by the charging and discharging testing system, the stress change characteristics of the electrode material of the rechargeable battery during the charging process can be tested by the optical fiber stress testing system, and the gas production characteristics of the electrode material of the rechargeable battery during the charging process can be tested by the differential electrochemical mass spectrometry testing system; thus, the failure mechanism of the electrode material of the rechargeable battery during the charging process is clarified by the stress change characteristics and the gas production characteristics.

[0030] Preferably, in the step S4, the way of obtaining the stress change characteristics comprises:

[0031] Step S4-1, according to the output light, obtaining the wavelength shift change amount of the optical fiber probe relative to the initial moment of the charging process during the charging process of the rechargeable battery ;

[0032] Step S4-2, according to the wavelength shift change amount , determining the stress change characteristics of the electrode material of the rechargeable battery during the charging process.

[0033] Preferably, the step S4-1 comprises:

[0034] Step S4-1a, obtaining a cladding mode signal or a surface plasmon resonance signal (i.e. SPR signal) from the output light; wherein the cladding mode signal is obtained by a fiber probe composed of a fiber core and a cladding which are sequentially sleeved from inside to outside, and the surface plasmon resonance signal (i.e. SPR signal) is obtained by a fiber probe composed of a fiber core, a cladding and a surface plasmon resonance layer (i.e. SPR layer) which are sequentially sleeved from inside to outside;

[0035] Step S4-1b, calculating the wavelength shift variation of the output light according to the cladding mode signal or the surface plasmon resonance signal (i.e. SPR signal) 。

[0036] Preferably, the fiber probe is an optical fiber with a fiber Bragg grating (FBG), and the stress change characteristic of the electrode material of the rechargeable battery during the charging process is calculated according to the following formula in step S4-2:

[0037] [Formula One]

[0038] [Formula Two]

[0039] [Formula Three]

[0040] [Formula Four]

[0041] In the formula, is the Bragg wavelength of the output light at the initial moment of the charging process of the rechargeable battery (2), is the effective refractive index of the guided mode in the fiber probe (1), which is generally 1.45 according to the material properties, is the period of refractive index modulation; is the Bragg wavelength of the output light during the charging process of the rechargeable battery (2), is the wavelength shift variation of the fiber probe (1) relative to the initial moment of the charging process during the charging process of the rechargeable battery (2); is the effective photoelastic coefficient, is the strain change occurring around the fiber probe (1); is the Young's modulus; stress variation characteristics of electrode materials of the rechargeable battery (2) during charging.

[0042] Preferably, in the step S5, the gas production characteristics are obtained by detecting the gas output from the gas outlet channel by the differential electrochemical mass spectrometry testing system, measuring the mass-to-charge ratio (m / z) of the gas output from the gas outlet channel, and determining the type of the gas output from the gas outlet channel by the measured mass-to-charge ratio (m / z), for example, one or more of CO, CO2, O2, H2, CH4, C2H6 and HF that may be produced by the rechargeable battery during charging, thereby obtaining the gas production characteristics of the electrode materials of the rechargeable battery during charging.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] The rechargeable battery to be analyzed and the optical fiber probe thereof are coupled to the optical fiber stress testing system and the differential electrochemical mass spectrometry testing system by the battery model, so that when the rechargeable battery is charged and discharged by the charging and discharging testing system, the stress variation characteristics of the electrode materials of the rechargeable battery during charging can be tested by the optical fiber stress testing system, and the gas production characteristics of the electrode materials of the rechargeable battery during charging can be tested by the differential electrochemical mass spectrometry testing system; thus, the failure mechanism of the electrode materials of the rechargeable battery during charging is clarified by the stress variation characteristics and the gas production characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0045] The present application will be further described in detail below in combination with the drawings and specific embodiments:

[0046] Fig. 1 is a structural schematic view of a battery model and a rechargeable battery installed therein in the present application;

[0047] Fig. 2 is a structural schematic view of an optical fiber probe in Embodiment Three of the present application;

[0048] Fig. 3 is a structural schematic view of a differential electrochemical mass spectrometry testing system in Embodiment Three of the present application;

[0049] Fig. 4 is a reflection spectrum diagram obtained by testing in Embodiment Three of the present application;

[0050] Fig. 5 is a graph of the relationship between voltage and strain obtained by testing in Embodiment Three of the present application;

[0051] Fig. 6 is a graph of the relationship between voltage and stress obtained by testing in Embodiment Three of the present application;

[0052] Fig. 7 is a graph of the relationship between voltage and SOC obtained by testing in Embodiment Three of the present application. DETAILED DESCRIPTION ​

[0053] The application will be described in greater detail below with reference to the embodiments and drawings, to help those skilled in the art better understand the inventive concept of the application, but the protection scope of the claims of the application is not limited to the following embodiments, and all other embodiments obtained by those skilled in the art without creative labor on the premise of not departing from the inventive concept of the application belong to the protection scope of the application.

[0054] Embodiment one

[0055] As shown in FIG. 1, the application discloses a battery in-situ failure analysis system, which is suitable for a rechargeable battery 2 internally provided with an optical fiber probe 1, and the optical fiber probe 1 is in contact with at least one of a positive electrode tab 2-1, an electrolyte 2-2 and a negative electrode tab 2-3 of the rechargeable battery 2, and both ends of the optical fiber probe 1 are exposed outside the rechargeable battery 2; wherein the rechargeable battery 2 can be a lithium ion battery, a solid-state battery, a semi-solid-state battery, a sodium ion battery, a water-based zinc ion battery, a lithium metal battery or a battery with the same structure.

[0056] The battery in-situ failure analysis system comprises a battery model, a charge-discharge test system, an optical fiber stress test system and a differential electrochemical mass spectrometry test system.

[0057] The battery model has a battery model shell 7 provided with a positive electrode terminal post 3, a negative electrode terminal post 4, an air inlet channel 5, an air outlet channel 6 and a model sealed inner cavity 7a, wherein the air inlet channel 5 and the air outlet channel 6 are respectively communicated with the model sealed inner cavity 7a; and when the rechargeable battery 2 is installed into the battery model, the rechargeable battery 2 is fixed in the model sealed inner cavity 7a, and the positive electrode terminal post 3 and the negative electrode terminal post 4 are respectively electrically connected with the tabs on the positive electrode tab 2-1 and the negative electrode tab 2-3 of the rechargeable battery 2.

[0058] The charge-discharge test system can charge and discharge the rechargeable battery 2 installed in the battery model through the positive electrode terminal post 3 and the negative electrode terminal post 4 according to a preset charge-discharge program; wherein the charge-discharge program can be constant current charge-discharge, constant voltage charge-discharge, constant power charge-discharge, etc., and the constant current charge-discharge current can be selected as C / 5, C / 10, C / 15, C / 20, C / 30, etc.

[0059] The optical fiber stress test system can guide input light into the optical fiber probe 1 and detect the output light transmitted through the optical fiber probe 1 to obtain the stress change characteristics of the electrode material of the rechargeable battery 2 during the charging process.

[0060] The differential electrochemical mass spectrometry test system can inject inert gas into the model sealed inner cavity 7a through the gas inlet channel 5, and detect the gas output from the gas outlet channel 6, so as to obtain the gas production characteristics of the electrode material of the rechargeable battery 2 during the charging process; wherein the inert gas can be argon, helium, neon, etc., and the gas purity is 99.999%.

[0061] The above is the basic implementation of the first embodiment, which can be further optimized, improved and limited on the basis of the basic implementation:

[0062] Preferably, the optical fiber probe 1 is arranged at the junction position of the positive electrode plate 2-1 and the electrolyte 2-2, or at the junction position of the negative electrode plate 2-3 and the electrolyte 2-2.

[0063] Preferably, the battery model shell 7 is composed of a positive side top cover 7-1 provided with the positive terminal post 3 and a negative side base 7-2 provided with the negative terminal post 4, and the positive side top cover 7-1 and the negative side base 7-2 are combined to form the model sealed inner cavity 7a. The via hole on the battery model shell 7 can be sealed by coating epoxy resin.

[0064] Wherein:

[0065] The optical fiber probe 1 can be any one of a fiber with a grating, a fiber with a cavity, a micro fiber, a nano fiber, a tapered fiber, a side-polished fiber, a microstructure fiber and a photonic crystal fiber; the fiber with a grating can be any one of a fiber Bragg grating (FBG), a tilted fiber Bragg grating (TFBG), a long period fiber grating (LPG), a chirped fiber grating and a phase-shifted grating.

[0066] The optical fiber probe 1 is preferably composed of a fiber core and a cladding which are sequentially sleeved from inside to outside, and the fiber core is provided with an inclined grating, and the inclination angle of the inclined grating relative to the longitudinal axis of the fiber core is less than 90 degrees. Preferably, the inclination angle of the inclined grating ranges from 2 degrees to 45 degrees. Further, the optical fiber probe 1 preferably further comprises a surface plasmon resonance layer (i.e. an SPR layer) coated on the outer surface of the cladding, wherein the SPR layer is a material capable of exciting surface plasmon resonance (SPR), and the material of the SPR layer can be any one of gold (Au), silver (Ag), platinum (Pt), copper (Cu), aluminum (Al), a semiconductor material, a metal oxide material, a two-dimensional (2D) material, and an optical super material. Further, the optical fiber probe 1 preferably further comprises a protective film layer coated on the outer surface of the surface plasmon resonance layer (i.e. the SPR layer), and the material of the protective film layer can be diamond, silicon, indium tin oxide (ITO), zinc peroxide (ZnO2), tin oxide (SnO2), indium oxide (In2O3), polyethylene (PE), or polypropylene (PP). Further, the optical fiber probe 1 preferably further comprises a transition film layer arranged between the cladding and the surface plasmon resonance layer (i.e. the SPR layer), and the transition film layer is used to improve the adhesion of the cladding to the fiber core, wherein the transition film layer can be any one of chromium (Cr), titanium (Ti), or molybdenum (Mo).

[0067] The working mode of the optical fiber probe 1 can be a transmission mode or a reflection mode.

[0068] When designed as the transmission mode, the light source device guides the input light into one end of the optical fiber probe 1, and the other end of the optical fiber probe 1 guides the output light and inputs the output light into the signal detection and processing device.

[0069] When designed as the reflection mode, the light source device and the signal detection and processing device are arranged at the same end of the optical fiber probe 1, and a mirror is arranged at the other end of the optical fiber probe 1, so that the input light guided by the light source device into the optical fiber probe 1 is transmitted forward through the optical fiber probe 1, reflected by the mirror, transmitted backward through the optical fiber probe 1, and then output to the signal detection and processing device. Further, in this mode, the system can further comprise a fiber circulator which is arranged between the light source device and the optical fiber probe along the input light path, and arranged between the optical fiber probe and the signal detection and processing device along the output light path. The fiber circulator separates the input light path and the output light path, so that the signal detection and processing device can be free from the influence of the input light, and further obtain the signal of the cladding mode or the SPR from the optical fiber probe.

[0070] The optical fiber probe 1 can be configured as a single point, or configured as multiple points through series and parallel connection.

[0071] Embodiment Two

[0072] The application also discloses a battery in-situ failure analysis method, which is implemented based on the battery in-situ failure analysis system in the first embodiment and comprises the following steps:

[0073] In step S1, the analyzed rechargeable battery 2 is installed into the battery model, and the connection between the battery model and the charge-discharge test system, the optical fiber stress test system and the differential electrochemical mass spectrum test system is completed.

[0074] In step S2, the differential electrochemical mass spectrum test system is used to inject inert gas into the model sealed inner cavity 7a through the gas inlet channel 5, so that the air in the model sealed inner cavity 7a is discharged through the gas outlet channel 6, that is, the model sealed inner cavity 7a is filled with the injected inert gas.

[0075] In step S3, the rechargeable battery 2 installed in the battery model is subjected to charge-discharge test by the charge-discharge test system.

[0076] In step S4, the optical fiber stress test system is used to guide input light into the optical fiber probe 1 and detect the output light transmitted through the optical fiber probe 1, so as to obtain the stress change characteristics of the electrode material of the rechargeable battery 2 in the charging process according to the output light; thus, whether there is an abnormal condition in the rechargeable battery 2, such as electrolyte aging, lithium dendrite growth, electrode material lattice structure damage, etc., can be judged by the stress change characteristics, and the failure mechanism of the electrode material in the charging process is clarified.

[0077] In step S5, the differential electrochemical mass spectrum test system is used to detect the gas output from the gas outlet channel 6, so as to obtain the gas production characteristics of the electrode material of the rechargeable battery 2 in the charging process; thus, the influence of the cycle life shortening, electrolyte decomposition and polarization increase of the rechargeable battery 2 can be judged by the gas production characteristics, and the failure mechanism of the electrode material in the charging process is clarified.

[0078] Therefore, the rechargeable battery 2 and the optical fiber probe 1 thereof to be analyzed are coupled with the optical fiber stress test system and the differential electrochemical mass spectrum test system respectively by the battery model, so that when the rechargeable battery 2 is subjected to charge-discharge by the charge-discharge test system, the stress change characteristics of the electrode material of the rechargeable battery 2 in the charging process can be tested by the optical fiber stress test system, and the gas production characteristics of the electrode material of the rechargeable battery 2 in the charging process can be tested by the differential electrochemical mass spectrum test system; thus, the failure mechanism of the electrode material of the rechargeable battery 2 in the charging process is clarified by the stress change characteristics and the gas production characteristics.

[0079] The above is the basic implementation manner of the second embodiment, and further optimization, improvement and limitation can be made on the basis of the basic implementation manner.

[0080] Preferably, in the step S4, the way of obtaining the stress change characteristic comprises:

[0081] In the step S4-1, the wavelength shift change amount of the fiber probe 1 relative to the initial moment of the charging process is obtained according to the output light.

[0082] In the step S4-2, the stress change characteristic of the electrode material of the rechargeable battery 2 in the charging process is determined according to the wavelength shift change amount.

[0083] Preferably, the step S4-1 comprises:

[0084] In the step S4-1a, a cladding mode signal or a surface plasmon resonance signal (i.e. SPR signal) is obtained from the output light; wherein the way of obtaining the cladding mode signal is suitable for the fiber probe 1 composed of a fiber core and a cladding which are sequentially sleeved from inside to outside, and the way of obtaining the surface plasmon resonance signal (i.e. SPR signal) is suitable for the fiber probe 1 composed of a fiber core, a cladding and a surface plasmon resonance layer (i.e. SPR layer) which are sequentially sleeved from inside to outside.

[0085] In the step S4-1b, the wavelength shift change amount is calculated according to the cladding mode signal or the surface plasmon resonance signal (i.e. SPR signal).

[0086] Preferably, the fiber probe 1 adopts an optical fiber with a fiber Bragg grating (FBG), and in the step S4-2, the stress change characteristic of the electrode material of the rechargeable battery 2 in the charging process is calculated according to the following formula:

[0087] [Formula One]

[0088] = [Formula Two]

[0089] [Formula Three]

[0090] [Formula Four]

[0091] ​​​wherein, is the Bragg wavelength of the output light at the initial moment of the charging process of the rechargeable battery (2), is the effective refractive index of the guided mode in the optical fiber probe (1), generally 1.45 according to the material properties, is the period of the refractive index modulation; is the Bragg wavelength of the output light during the charging process of the rechargeable battery (2), is the wavelength shift change of the optical fiber probe (1) relative to the initial moment of the charging process during the charging process of the rechargeable battery (2); is the effective photoelastic coefficient, is the strain change occurring around the optical fiber probe (1); is the Young's modulus; is the stress change characteristic of the electrode material of the rechargeable battery (2) during the charging process.

[0092] Preferably, in the step S5, the gas production characteristic is obtained by detecting the gas output from the gas outlet channel 6 with the differential electrochemical mass spectrometry test system, measuring the mass-to-charge ratio (m / z) of the gas output from the gas outlet channel 6, and determining the type of the gas output from the gas outlet channel 6 through the measured mass-to-charge ratio (m / z), for example, one or more of CO, CO2, O2, H2, CH4, C2H6, and HF that may be produced by the rechargeable battery 2 during the charging process, thereby obtaining the gas production characteristic of the electrode material of the rechargeable battery 2 during the charging process.

[0093] Embodiment Three

[0094] On the basis of the above-mentioned embodiment one or embodiment two, the embodiment three further adopts the following preferred implementation manner:

[0095] Referring to FIG. 2, the optical fiber probe 1 is composed of an optical fiber core 101, a cladding 102, and a surface plasmon resonance layer 103 (i.e., an SPR layer) which are sequentially sleeved from inside to outside, and the optical fiber core 101 is provided with an inclined light ray Bragg grating 104 (i.e., an FTBG); thus, the stress change characteristic of the electrode material of the rechargeable battery 2 during the charging process can be calculated through the formulas one to four.

[0096] And the optical fiber stress test system comprises a light source device and a signal detection processing device, the light source device can guide input light into the optical fiber probe 1, and the signal detection processing device can receive output light transmitted by the optical fiber probe 1 and convert the output light into an electric signal for detection, so as to obtain the stress change characteristics of the electrode material of the rechargeable battery 2 in the charging process. Wherein, the light source device can be a broadband light source or a tunable laser source, and the signal detection processing device can adopt a spectrum analyzer, or can adopt an optical detector and an analog-to-digital converter, so as to receive the output light transmitted by the optical fiber probe 1 with the optical detector and convert the output light into an analog electric signal, and then convert the analog electric signal into a digital electric signal by the analog-to-digital converter.

[0097] Referring to FIG. 3, the differential electrochemical mass spectrometry test system comprises: the gas outlet channel 6 is connected with the inlet of the differential electrochemical mass spectrometer 14 through a vacuum system pipeline 8, and the vacuum system pipeline 8 is sequentially provided with a water-blocking air-permeable film 9, a gas coarse adjustment valve 10, a mechanical pump 11, a gas fine adjustment valve 12 and a turbo pump 13 in the direction from the gas outlet channel 6 to the differential electrochemical mass spectrometer 14, so that the gas output from the gas outlet channel 6 enters the differential electrochemical mass spectrometer 14 through the pipeline for detection, and the detection data output by the differential electrochemical mass spectrometer 14 is analyzed by the data analysis software 15 to obtain the gas generation characteristics of the electrode material of the rechargeable battery 2 in the charging process.

[0098] The present application is tested on the battery in-situ failure analysis system described in embodiment three:

[0099] The test conditions are: the positive plate 2-1, the electrolyte 2-2 and the negative plate 2-3 of the rechargeable battery 2 are LTO, solid-state electrolyte and lithium-indium alloy respectively, the optical fiber probe 1 is located at the interface between the positive plate 2-1 and the electrolyte 2-2; the constant current charging and discharging current is C / 10, and the inert gas is Ar.

[0100] The test purposes are: to obtain the reflection spectrum, the relationship between voltage and strain, the relationship between voltage and stress, and the relationship with SOC, so as to study the stress change of the battery in the charging and discharging process, and effectively evaluate the capacity stability of the battery.

[0101] As shown in FIG. 4, it is the reflection spectrum obtained by testing, the initial is denoted as For the recorded spectrum, a single Bragg wavelength peak can be seen, which moves to the right during charging and moves to the left during discharging. It can be inferred that, under the condition of continuous cycle, with the charging and discharging, the peak will move repeatedly from right to left, so as to judge the mechanical reversibility of the battery.

[0102] Figure 5 shows the relationship between voltage and strain obtained from the test. It illustrates how strain changes with voltage during one charge-discharge cycle. As shown in the figure, the voltage continuously increases during battery charging. It also continues to increase, and when the voltage reaches 1.3 V, It is 0.03, and as the discharge proceeds, The gradual decrease indicates that the battery has good cycle performance, low internal resistance, and lithium ions can freely insert / deintercalate.

[0103] Figure 6 shows the relationship between voltage and stress obtained from the test, illustrating how stress changes with voltage. The stress and strain in Figures 5 and 6 exhibit the same trend with voltage, calculated based on Hooke's law within one charge-discharge cycle. A pressure less than 2 MPa indicates that the battery has good capacity retention. This embodiment provides an effective method and research evidence to successfully couple the fiber optic stress testing system and the charge-discharge system through a battery model, enabling real-time monitoring of the stress and strain evolution of the lithium battery during charge-discharge, and intuitively obtaining numerical values ​​of electrode freshness / aging. This is crucial for improving lithium battery life and assessing battery safety.

[0104] As shown in Figure 7, the results obtained from the test are as follows. The graph showing the relationship between SOC and discharge process is as follows: Relationship with State of Charge (SOC). During discharge, lithium ions are extracted from the negative electrode, pass through the separator, and enter the positive electrode. Electrons are transferred from the external circuit to the positive electrode. If there are significant changes in the internal stress of the electrode during this process, it will affect the normal transport of lithium ions, potentially leading to lithium source loss, a decrease in lithium concentration, and a reduction in SOC. Therefore, monitoring... Changes in State of Charge (SOC) can effectively provide information about a battery's capacity. As shown in the figure, when the battery's SOC is 100%, the pressure is 5.6 MPa. As discharge progresses, the stress gradually decreases with decreasing SOC. A fiber optic stress testing system can accurately obtain the battery's state of charge, providing a basis for evaluating the battery's true capacity.

[0105] This invention is not limited to the specific embodiments described above. Based on the above content and in accordance with common technical knowledge and conventional methods in the field, without departing from the basic technical concept of this invention, this invention can also make other equivalent modifications, substitutions or alterations, all of which fall within the protection scope of this invention.

Claims

1. A battery in-situ failure analysis system, characterized by: The application is suitable for a rechargeable battery (2) with an optical fiber probe (1) arranged inside, and the optical fiber probe (1) is in contact with at least one of the positive electrode tab (2-1), the electrolyte (2-2) and the negative electrode tab (2-3) of the rechargeable battery (2), and both ends of the optical fiber probe (1) are exposed outside the rechargeable battery (2); The battery in-situ failure analysis system comprises a battery model, a charge-discharge test system, an optical fiber stress test system and a differential electrochemical mass spectrum test system. The battery model is provided with a battery model shell (7) provided with a positive electrode terminal post (3), a negative electrode terminal post (4), an air inlet channel (5), an air outlet channel (6) and a model sealed inner cavity (7a), wherein the air inlet channel (5) and the air outlet channel (6) are respectively communicated with the model sealed inner cavity (7a); and when the rechargeable battery (2) is installed into the battery model, the rechargeable battery (2) is fixed in the model sealed inner cavity (7a), and the positive electrode terminal post (3) and the negative electrode terminal post (4) are respectively electrically connected with the tabs on the positive electrode tab (2-1) and the negative electrode tab (2-3) of the rechargeable battery (2). The charge-discharge test system can charge and discharge the rechargeable battery (2) installed in the battery model according to a preset charge-discharge program through the positive electrode terminal post (3) and the negative electrode terminal post (4). The optical fiber stress test system can guide input light into the optical fiber probe (1) and detect output light transmitted through the optical fiber probe (1) to obtain stress change characteristics of electrode materials of the rechargeable battery (2) during charging. The differential electrochemical mass spectrum test system can inject inert gas into the model sealed inner cavity (7a) through the air inlet channel (5) and detect gas output from the air outlet channel (6) to obtain gas production characteristics of electrode materials of the rechargeable battery (2) during charging.

2. The battery in-situ failure analysis system of claim 1, wherein: The optical fiber probe (1) is arranged at the junction position of the positive electrode tab (2-1) and the electrolyte (2-2), or at the junction position of the negative electrode tab (2-3) and the electrolyte (2-2).

3. The battery in-situ failure analysis system of claim 1, wherein: The battery model shell (7) is composed of a positive electrode side top cover (7-1) provided with the positive electrode terminal post (3) and a negative electrode side base (7-2) provided with the negative electrode terminal post (4), and the positive electrode side top cover (7-1) and the negative electrode side base (7-2) combine to form the model sealed inner cavity (7a).

4. The battery in situ failure analysis system of any one of claims 1 to 3, wherein: The optical fiber probe (1) is composed of an optical fiber core (101), a cladding layer (102) and a surface plasmon resonance layer (103) which are sequentially sleeved from inside to outside, and the optical fiber core (101) is provided with an inclined optical Bragg grating (104). Furthermore, the optical fiber stress test system comprises a light source device and a signal detection and processing device, the light source device can guide input light into the optical fiber probe (1), and the signal detection and processing device can receive output light transmitted through the optical fiber probe (1) and convert the output light into an electric signal for detection to obtain stress change characteristics of electrode materials of the rechargeable battery (2) during charging.

5. The battery in situ failure analysis system of any one of claims 1 to 3, wherein: The differential electrochemical mass spectrometry test system comprises: the gas outlet channel (6) is connected with the inlet of the differential electrochemical mass spectrometer (14) through a vacuum system pipeline (8), and the vacuum system pipeline (8) is sequentially provided with a water-blocking and air-permeating film (9), a gas coarse adjustment valve (10), a mechanical pump (11), a gas fine adjustment valve (12) and a turbo pump (13) in the direction from the gas outlet channel (6) to the differential electrochemical mass spectrometer (14).

6. A method for in-situ battery failure analysis, the method comprising: The in-situ failure analysis system for the battery according to any one of claims 1 to 5 is implemented, comprising: Step S1, installing the analyzed rechargeable battery (2) into the battery model, and completing the connection between the battery model and the charge-discharge test system, the optical fiber stress test system and the differential electrochemical mass spectrometry test system; Step S2, injecting inert gas into the model sealed inner cavity (7a) through the gas inlet channel (5) by using the differential electrochemical mass spectrometry test system, so that the air in the model sealed inner cavity (7a) is discharged through the gas outlet channel (6); Step S3, performing charge-discharge test on the rechargeable battery (2) installed in the battery model by using the charge-discharge test system; Step S4, guiding input light into the optical fiber probe (1) by using the optical fiber stress test system, and detecting the output light transmitted through the optical fiber probe (1) to obtain the stress change characteristics of the electrode material of the rechargeable battery (2) in the charging process according to the output light; Step S5, detecting the gas output from the gas outlet channel (6) by using the differential electrochemical mass spectrometry test system to obtain the gas production characteristics of the electrode material of the rechargeable battery (2) in the charging process.

7. The method of claim 6, wherein: In the step S4, the stress change characteristics are obtained by: Step S4-1, according to the output light, obtaining: a wavelength shift variation amount of the optical fiber probe (1) relative to an initial moment of the charging process in the charging process of the rechargeable battery (2) ； Step S4-2, changing the wavelength shift according to the wavelength shift variation determining the stress change characteristics of the electrode material of the rechargeable battery (2) in the charging process.

8. The method of claim 7, wherein: The step S4-1 comprises: Step S4-1a, obtaining a cladding mode signal or a surface plasmon resonance signal from the output light; wherein the cladding mode signal is obtained by using the optical fiber probe (1) composed of a fiber core and a cladding layer which are sequentially sleeved from inside to outside, and the surface plasmon resonance signal is obtained by using the optical fiber probe (1) composed of a fiber core, a cladding layer and a surface plasmon resonance layer which are sequentially sleeved from inside to outside; Step S4-1b, calculating the amount of change in the wavelength shift from the cladding mode signal or the surface plasmon resonance signal 。 9. The method of claim 7 or 8, wherein: The optical fiber probe (1) uses an optical fiber with a fiber Bragg grating, and in the step S4-2, the stress change characteristics of the electrode material of the rechargeable battery (2) in the charging process are calculated according to the following formula: [Formula One] = [Formula Two] [Formula Three] [Formula Four] In the formulae, for the Bragg wavelength of the output light at the initial moment of the charging process of the rechargeable battery (2), the effective refractive index of the guided mode in the optical fiber probe (1), for the refractive index modulation; for the output light in the Bragg wavelength during charging of the rechargeable battery (2), a wavelength shift variation amount of the optical fiber probe (1) with respect to a charging process initial time in a charging process of the rechargeable battery (2); effective photoelastic coefficient, for a change in strain occurring around the optical fiber probe (1); Young's modulus; The stress change characteristics of the electrode material of the rechargeable battery (2) in the charging process.

10. The method of claim 6, wherein: In the step S5, the gas production characteristics are obtained by: detecting the gas output from the gas outlet channel (6) by using the differential electrochemical mass spectrometry test system, measuring the mass-to-charge ratio of the gas output from the gas outlet channel (6), and determining the type of the gas output from the gas outlet channel (6) through the measured mass-to-charge ratio, thereby obtaining the gas production characteristics of the electrode material of the rechargeable battery (2) in the charging process.

Images