Battery in-situ failure analysis system and method

Abstract

The present invention discloses a battery in-situ failure analysis system and method, which are applicable to a rechargeable battery pre-equipped with an optical fiber probe. The battery in-situ failure analysis system comprises: a battery model, a charge and discharge test system, an optical fiber stress test system and a differential electrochemical mass spectrometry test system. The rechargeable battery to be analyzed and its optical fiber probe are coupled with the optical fiber stress test system and the differential electrochemical mass spectrometry test system respectively through the battery model, so that when the charge and discharge test system charges and discharges the rechargeable battery, it is possible to simultaneously achieve: the stress change characteristics of the electrode material of the rechargeable battery during the charging process are tested by the optical fiber stress test system, and the gas generation characteristics of the electrode material of the rechargeable battery during the charging process are tested by the differential electrochemical mass spectrometry test system. Therefore, the failure mechanism of the electrode material of the rechargeable battery during the charging process is explained through the stress change characteristics and the gas generation characteristics.

Description

Technical Field

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

[0002] Rechargeable lithium-ion batteries are widely used in consumer electronics, power grids, aerospace, and electric vehicles due to their outstanding performance in energy density, affordability, and environmental footprint. However, frequent lithium battery fires, explosions, gas leaks, and poor durability pose a serious threat to people's lives. Currently, battery management systems (BMS) are mainly used to monitor battery data and adjust charging and discharging strategies. Alternatively, in-situ X-ray diffractometers and operational electron microscopes are used to track the volume and stress changes caused by lithium intercalation and deintercalation in the electrodes. However, the sensors of these technologies are often placed on the outside of the battery and cannot monitor the local stress changes in the electrodes in real time. In addition, batteries are prone to gas generation during long-term cycling, overcharge, over-discharge, or thermal abuse, leading to performance degradation. To address these issues, it is urgent to develop local and non-invasive manipulation techniques combined with specific battery designs to detect stress changes and gas generation characteristics within the battery / interface under realistic charging and discharging conditions. Summary of the Invention

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

[0004] To solve the above technical problems, the technical solutions adopted by the present invention are 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 installed inside, and the optical fiber probe contacts at least one of the positive electrode plate, electrolyte and negative electrode plate of the rechargeable battery, and both 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, an aqueous zinc-ion battery, a lithium metal battery or a battery with the same structure.

[0006] The battery in-situ failure analysis system includes: a battery model, a charge and discharge test system, an optical fiber stress test system and a differential electrochemical mass spectrometry test system;

[0007] The battery model comprises a battery model housing having a positive terminal, a negative terminal, an air inlet channel, an air outlet channel, and a sealed inner cavity of the model, wherein the air inlet channel and the air outlet channel are respectively connected to the sealed inner cavity of the model; and when the rechargeable battery is installed in the battery model, the rechargeable battery is fixed in the sealed inner cavity of the model, and the positive terminal and the negative terminal are respectively electrically connected to the tabs on the positive and negative electrode sheets of the rechargeable battery;

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

[0009] The optical fiber stress testing system is capable of introducing input light into the optical fiber probe and detecting output light transmitted by the optical fiber probe to obtain stress change characteristics of the electrode material of the rechargeable battery during charging;

[0010] The differential electrochemical mass spectrometry testing system is capable of injecting an inert gas into the sealed inner cavity of the model through the air inlet channel and detecting the gas output from the air outlet channel to obtain the gas generation 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 interface between the positive electrode plate and the electrolyte, or at the interface between the negative electrode plate and the electrolyte.

[0012] Preferably, the battery model housing comprises a positive-side top cover having the positive terminal and a negative-side base having the negative terminal. The positive-side top cover and the negative-side base are combined to form the sealed inner cavity of the model. The vias in the battery model housing can be sealed by coating with epoxy resin.

[0013] in:

[0014] The optical fiber probe can be any one of an optical fiber with a grating, a cavity optical fiber, a micro optical fiber, a nano optical fiber, a tapered optical fiber, a side-polished optical fiber, a microstructured optical fiber and a photonic crystal optical fiber; the optical fiber with a grating can have a grating type of 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 is preferably composed of an optical fiber core and a cladding that are sequentially sleeved from the inside to the outside, and a tilted grating is provided on the optical fiber core, and the tilt angle of the tilted grating relative to the longitudinal axis of the optical fiber core is less than 90 degrees. Moreover, the tilt angle range of the tilted grating is preferably 2 degrees to 45 degrees. Further, the optical fiber probe preferably also includes a surface plasmon resonance layer (i.e., SPR layer) coated on the outer surface of the cladding, wherein the SPR layer is a material for 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 materials, metal oxide materials, two-dimensional (2D) materials, and optical metamaterials. Further, the optical fiber probe preferably also includes 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). Furthermore, the optical fiber probe preferably also includes 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 optical 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 in transmission mode, the light source device introduces input light from one end of the optical fiber probe, and output light is extracted from the other end of the optical fiber probe and input into the signal detection and processing device.

[0018] When designed in 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 reflector is provided at the other end of the optical fiber probe, so that the input light introduced by the light source device to the optical fiber probe is transmitted forward by the optical fiber probe, reflected by the reflector, and then transmitted backward by the optical fiber probe before being output to the signal detection and processing device. Furthermore, in this mode, the system can also include a fiber optic circulator, which is arranged between the light source device and the optical fiber probe along the input optical path and between the optical fiber probe and the signal detection and processing device along the output optical path. The fiber optic circulator separates the input optical path and the output optical path, so that the signal detection and processing device can be unaffected by the input light, thereby obtaining the cladding mode or SPR signal from the optical fiber probe.

[0019] The optical fiber probe can be configured at a single point or at multiple points through serial and parallel connections.

[0020] As a preferred embodiment of the present invention: Figure 2The optical fiber probe is composed of an optical fiber core, a cladding, and a surface plasmon resonance layer (i.e., an SPR layer) sequentially arranged from the inside to the outside, and the optical fiber core has a tilted fiber 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 using Formulas 1 to 4.

[0021] Furthermore, the optical fiber stress testing system includes a light source device and a signal detection and processing device. The light source device is capable of directing input light into the optical fiber probe, and the signal detection and processing device is capable of receiving output light transmitted by the optical fiber probe and converting the output light into an electrical signal for detection, thereby obtaining 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 be a spectrum analyzer or an optical detector and an analog-to-digital converter. The optical detector receives the output light transmitted by the optical fiber probe and converts it into an analog electrical signal, which is then converted into a digital electrical signal by the analog-to-digital converter.

[0022] As a preferred embodiment of the present invention: Figure 3 The differential electrochemical mass spectrometry testing system includes: 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 installed with a water-blocking and breathable membrane, a gas coarse regulating valve, a mechanical pump, a gas fine regulating valve, and a turbine pump in sequence 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 line 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 it is implemented based on the battery in-situ failure analysis system, and includes:

[0024] Step S1: Install the rechargeable battery to be analyzed into the battery model, and complete the connection between the battery model and the charge and discharge test system, the optical fiber stress test system, and the differential electrochemical mass spectrometry test system;

[0025] Step S2: using the differential electrochemical mass spectrometry testing system to inject an inert gas into the sealed inner cavity of the model through the air inlet channel, so that the air in the sealed inner cavity of the model is discharged through the air outlet channel, that is, the sealed inner cavity of the model is filled with the injected inert gas;

[0026] Step S3, using the charge and discharge test system to perform a charge and discharge test on the rechargeable battery installed in the battery model;

[0027] Step S4: Use the optical fiber stress testing system to introduce input light into the optical fiber probe, and detect the output light transmitted by the optical fiber probe to obtain the stress change characteristics of the electrode material of the rechargeable battery during the charging process based on the output light; thereby, it is possible to determine whether there is an abnormality inside the rechargeable battery, such as electrolyte aging, lithium dendrite growth, damage to the electrode material lattice structure, etc., through the stress change characteristics, and clarify the failure mechanism of the electrode material during the charging process.

[0028] Step S5: Use the differential electrochemical mass spectrometry testing system to detect the gas output from the gas outlet channel to obtain the gas generation characteristics of the electrode material during the charging process of the rechargeable battery; thereby, the gas generation characteristics can be used to determine the effects of shortened cycle life, electrolyte decomposition, and increased polarization of the rechargeable battery, and the failure mechanism of the electrode material during the charging process is clarified.

[0029] Therefore, the present invention couples the rechargeable battery to be analyzed and its optical fiber probe with the optical fiber stress testing system and the differential electrochemical mass spectrometry testing system respectively through a battery model, so that when the charge and discharge testing system charges and discharges the rechargeable battery, it can simultaneously achieve: the stress change characteristics of the electrode material of the rechargeable battery during the charging process are tested by the optical fiber stress testing system, and the gas generation characteristics of the electrode material of the rechargeable battery during the charging process are 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 explained through the stress change characteristics and the gas generation characteristics.

[0030] Preferably, in step S4, the method of obtaining the stress change characteristics includes:

[0031] Step S4-1: Obtain, based on the output light: a wavelength shift change Δλ of the optical fiber probe during the charging process of the rechargeable battery relative to the initial moment of the charging process; B ;

[0032] Step S4-2: according to the wavelength shift variation Δλ B , determine the stress change characteristics of the electrode material of the rechargeable battery during the charging process.

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

[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 method for obtaining the cladding mode signal is applicable to an optical fiber probe consisting of an optical fiber core and a cladding sequentially arranged from the inside out, and the method for obtaining the surface plasmon resonance signal (i.e., SPR signal) is applicable to an optical fiber probe consisting of an optical fiber core, a cladding, and a surface plasmon resonance layer (i.e., SPR layer) sequentially arranged from the inside out;

[0035] Step S4-1b: Calculate the wavelength shift variation Δλ based on the cladding mode signal or surface plasmon resonance signal (ie, SPR signal). B .

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

[0037] λ B,0 =2n eff ∧ [Formula 1]

[0038] Δλ B =λ B -λ B,0 [Formula 2]

[0039] Δλ B / λ B,0 =(1-p e )ε [Formula 3]

[0040] σ=Eε [Formula 4]

[0041] Where λ B,0 is the Bragg wavelength of the output light at the initial moment of the charging process of the rechargeable battery (2), n eff is the effective refractive index of the guided mode in the optical fiber probe (1), which is generally 1.45 according to the material properties, and ∧ is the period of refractive index modulation; B is the Bragg wavelength of the output light during the charging process of the rechargeable battery (2), Δλ B is the wavelength shift variation of the optical fiber probe (1) during the charging process of the rechargeable battery (2) relative to the initial moment of the charging process; p e is the effective photoelastic coefficient, ε is the strain change occurring around the optical fiber probe (1); E is the Young's modulus; and σ is the stress change characteristic of the electrode material of the rechargeable battery (2) during the charging process.

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

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

[0044] The present invention couples a rechargeable battery to be analyzed and its optical fiber probe with an optical fiber stress testing system and a differential electrochemical mass spectrometry testing system respectively through a battery model, so that when the charge-discharge testing system charges and discharges the rechargeable battery, the following can be achieved simultaneously: the stress change characteristics of the electrode material of the rechargeable battery during the charging process are tested by the optical fiber stress testing system, and the gas generation characteristics of the electrode material of the rechargeable battery during the charging process are 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 explained through the stress change characteristics and the gas generation characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0046] Figure 1 A schematic structural diagram of a battery model and a rechargeable battery installed therein in the present invention;

[0047] Figure 2 Schematic diagram of the structure of the optical fiber probe according to the third embodiment of the present invention;

[0048] Figure 3 Schematic diagram of the structure of the differential electrochemical mass spectrometry testing system according to the third embodiment of the present invention;

[0049] Figure 4 This is a reflection spectrum obtained by testing Example 3 of the present invention;

[0050] Figure 5 This is a graph showing the relationship between voltage and strain obtained from testing in Example 3 of the present invention;

[0051] Figure 6 This is a relationship diagram between voltage and stress obtained by testing in Example 3 of the present invention;

[0052] Figure 7 This is a relationship diagram between Δσ and SOC obtained by testing in Example 3 of the present invention. DETAILED DESCRIPTION

[0053] The present invention is described in detail below in conjunction with the embodiments and the accompanying drawings to help those skilled in the art better understand the inventive concept of the present invention. However, the scope of protection of the claims of the present invention is not limited to the following embodiments. For those skilled in the art, all other embodiments obtained without creative work without departing from the inventive concept of the present invention shall fall within the scope of protection of the present invention.

[0054] Example 1

[0055] like Figure 1As shown, the present invention discloses a battery in-situ failure analysis system, which is suitable for a rechargeable battery 2 with an optical fiber probe 1 installed inside, and the optical fiber probe 1 is in contact with at least one of the positive electrode plate 2-1, the electrolyte 2-2 and the negative electrode plate 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, an aqueous zinc-ion battery, a lithium metal battery or a battery with the same structure.

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

[0057] The battery model comprises a battery model housing 7 having a positive terminal 3, a negative terminal 4, an air inlet channel 5, an air outlet channel 6, and a sealed inner cavity 7a of the model, wherein the air inlet channel 5 and the air outlet channel 6 are respectively connected to the sealed inner cavity 7a of the model; and when the rechargeable battery 2 is installed in the battery model, the rechargeable battery 2 is fixed in the sealed inner cavity 7a of the model, and the positive terminal 3 and the negative terminal 4 are respectively electrically connected to the tabs on the positive electrode sheet 2-1 and the negative electrode sheet 2-3 of the rechargeable battery 2;

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

[0059] The optical fiber stress testing system is capable of introducing input light into the optical fiber probe 1 and detecting output light transmitted by the optical fiber probe 1 to obtain stress change characteristics of the electrode material of the rechargeable battery 2 during the charging process;

[0060] The differential electrochemical mass spectrometry testing system can inject an inert gas into the sealed inner cavity 7a of the model through the inlet channel 5 and detect the gas output from the outlet channel 6 to obtain the gas generation 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 a basic implementation of the first embodiment of the present invention. Further optimization, improvement and limitation can be made based on this basic implementation:

[0062] Preferably, the optical fiber probe 1 is arranged at the interface between the positive electrode piece 2-1 and the electrolyte 2-2, or at the interface between the negative electrode piece 2-3 and the electrolyte 2-2.

[0063] Preferably, the battery model housing 7 is composed of a positive-side top cover 7-1 equipped with the positive terminal 3 and a negative-side base 7-2 equipped with the negative terminal 4. 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 vias in the battery model housing 7 can be sealed by coating with epoxy resin.

[0064] in:

[0065] The optical fiber probe 1 can be any one of an optical fiber with a grating, a cavity optical fiber, a micro optical fiber, a nano optical fiber, a tapered optical fiber, a side-polished optical fiber, a microstructured optical fiber and a photonic crystal optical fiber; the optical fiber with a grating can have a grating type of 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 an optical fiber core and a cladding that are sequentially sleeved from the inside to the outside, and a tilted grating is provided on the optical fiber core, and the tilted grating is less than 90 degrees relative to the longitudinal axis of the optical fiber core. Moreover, the tilt angle range of the tilted grating is preferably 2 degrees to 45 degrees. Further, the optical fiber probe 1 preferably also includes a surface plasmon resonance layer (i.e., SPR layer) coated on the outer surface of the cladding, wherein the SPR layer is a material for 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 materials, metal oxide materials, two-dimensional (2D) materials, and optical metamaterials. Furthermore, the optical fiber probe 1 preferably also includes 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). Furthermore, the optical fiber probe 1 preferably also includes 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 optical 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 in transmission mode, the light source device introduces input light from one end of the optical fiber probe 1 and extracts output light from the other end of the optical fiber probe 1 and inputs it into the signal detection and processing device.

[0069] When designed in 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 reflector is provided at the other end of the optical fiber probe 1, so that the input light introduced by the light source device to the optical fiber probe 1 is transmitted forward through the optical fiber probe 1, reflected by the reflector, and then transmitted backward through the optical fiber probe 1 before being output to the signal detection and processing device. Furthermore, in this mode, the system can also include a fiber optic circulator, which is arranged between the light source device and the optical fiber probe along the input optical path and between the optical fiber probe and the signal detection and processing device along the output optical path. The fiber optic circulator separates the input optical path and the output optical path, so that the signal detection and processing device is not affected by the input light, and thus obtains the cladding mode or SPR signal from the optical fiber probe.

[0070] The optical fiber probe 1 can be configured in a single point or in a multi-point configuration through serial and parallel connections.

[0071] Example 2

[0072] The present invention also discloses a battery in-situ failure analysis method, which is implemented based on the battery in-situ failure analysis system described in Example 1 and includes:

[0073] Step S1, installing the rechargeable battery 2 to be analyzed into the battery model, and completing the connection between the battery model and the charge and discharge test system, the optical fiber stress test system, and the differential electrochemical mass spectrometry test system;

[0074] Step S2: Injecting an inert gas into the mold sealed inner cavity 7a through the air inlet channel 5 using the differential electrochemical mass spectrometry testing system, so that the air in the mold sealed inner cavity 7a is discharged through the air outlet channel 6, that is, the mold sealed inner cavity 7a is filled with the injected inert gas;

[0075] Step S3: using the charge-discharge test system to perform a charge-discharge test on the rechargeable battery 2 installed in the battery model;

[0076] Step S4: Use the optical fiber stress testing system to introduce input light into the optical fiber probe 1, and detect the output light transmitted by the optical fiber probe 1 to obtain the stress change characteristics of the electrode material of the rechargeable battery 2 during the charging process based on the output light; thereby, it is possible to judge whether there is an abnormality inside the rechargeable battery 2, such as electrolyte aging, lithium dendrite growth, damage to the lattice structure of the electrode material, etc., through the stress change characteristics, and clarify the failure mechanism of the electrode material during the charging process.

[0077] Step S5: Use the differential electrochemical mass spectrometry testing system to detect the gas output from the gas outlet channel 6 to obtain the gas generation characteristics of the electrode material of the rechargeable battery 2 during the charging process; thereby, the effects of the shortened cycle life, electrolyte decomposition, and increased polarization of the rechargeable battery 2 can be determined through the gas generation characteristics, and the failure mechanism of the electrode material during the charging process can be clarified.

[0078] Therefore, the present invention couples the rechargeable battery 2 to be analyzed and its optical fiber probe 1 with the optical fiber stress testing system and the differential electrochemical mass spectrometry testing system respectively through a battery model, so that when the charge and discharge testing system charges and discharges the rechargeable battery 2, it can simultaneously achieve: the stress change characteristics of the electrode material of the rechargeable battery 2 during the charging process are tested by the optical fiber stress testing system, and the gas production characteristics of the electrode material of the rechargeable battery 2 during the charging process are tested by the differential electrochemical mass spectrometry testing system; thus, the failure mechanism of the electrode material of the rechargeable battery 2 during the charging process is explained through the stress change characteristics and the gas production characteristics.

[0079] The above is the basic implementation of the second embodiment. Further optimization, improvement and limitation can be made based on this basic implementation:

[0080] Preferably, in step S4, the method of obtaining the stress change characteristics includes:

[0081] Step S4-1: Based on the output light, obtain: the wavelength shift change Δλ of the optical fiber probe 1 during the charging process of the rechargeable battery 2 relative to the initial moment of the charging process; B ;

[0082] Step S4-2: according to the wavelength shift variation Δλ B , determine the stress change characteristics of the electrode material of the rechargeable battery 2 during the charging process.

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

[0084] Step S4-1a, obtaining a cladding mode signal or a surface plasmon resonance signal (i.e., SPR signal) from the output light; wherein the method for obtaining the cladding mode signal is applicable to an optical fiber probe 1 consisting of an optical fiber core and a cladding sequentially arranged from the inside to the outside, and the method for obtaining the surface plasmon resonance signal (i.e., SPR signal) is applicable to an optical fiber probe 1 consisting of an optical fiber core, a cladding, and a surface plasmon resonance layer (i.e., SPR layer) sequentially arranged from the inside to the outside;

[0085] Step S4-1b: Calculate the wavelength shift variation Δλ based on the cladding mode signal or surface plasmon resonance signal (ie, SPR signal). B .

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

[0087] λ B,0 =2n eff ∧ [Formula 1]

[0088] Δλ B =λ B -λ B,0 [Formula 2]

[0089] Δλ B / λ B,0 =(1-p e )ε [Formula 3]

[0090] σ=Eε [Formula 4]

[0091] Where λ B,0 is the Bragg wavelength of the output light at the initial moment of the charging process of the rechargeable battery (2), n eff is the effective refractive index of the guided mode in the optical fiber probe (1), which is generally 1.45 according to the material properties, and ∧ is the period of refractive index modulation; B is the Bragg wavelength of the output light during the charging process of the rechargeable battery (2), Δλ B is the wavelength shift variation of the optical fiber probe (1) during the charging process of the rechargeable battery (2) relative to the initial moment of the charging process; p e is the effective photoelastic coefficient, ε is the strain change occurring around the optical fiber probe (1); E is the Young's modulus; and σ is the stress change characteristic of the electrode material of the rechargeable battery (2) during the charging process.

[0092] Preferably, in step S5, the gas production characteristics are obtained by detecting the gas output from the gas outlet channel 6 using the differential electrochemical mass spectrometry testing system to measure the mass-to-charge ratio (m / z) of the gas output from the gas outlet channel 6, and determining the type of gas output from the gas outlet channel 6 by the measured mass-to-charge ratio (m / z), for example, one or more gases among 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 characteristics of the electrode material of the rechargeable battery 2 during the charging process.

[0093] Example 3

[0094] Based on the above-mentioned embodiment 1 or embodiment 2, this embodiment 3 further adopts the following preferred implementation manner:

[0095] See also Figure 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., SPR layer) sequentially arranged from the inside to the outside, and the optical fiber core 101 has a tilted fiber Bragg grating 104 (i.e., FTBG); therefore, the stress change characteristics of the electrode material of the rechargeable battery 2 during the charging process can be calculated using Formulas 1 to 4.

[0096] Furthermore, the optical fiber stress testing system includes a light source device and a signal detection and processing device. The light source device is capable of directing input light into the optical fiber probe 1. The signal detection and processing device is capable of receiving output light transmitted by the optical fiber probe 1 and converting the output light into an electrical signal for detection, thereby obtaining the stress change characteristics of the electrode material of the rechargeable battery 2 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 be a spectrum analyzer or an optical detector and an analog-to-digital converter. The optical detector receives the output light transmitted by the optical fiber probe 1 and converts it into an analog electrical signal. The analog-to-digital converter then converts the analog electrical signal into a digital electrical signal.

[0097] See also Figure 3 The differential electrochemical mass spectrometry testing system includes: the gas outlet channel 6 is connected to the inlet of the differential electrochemical mass spectrometer 14 through the vacuum system pipeline 8, and the vacuum system pipeline 8 is installed with a water-blocking and breathable membrane 9, a gas coarse regulating valve 10, a mechanical pump 11, a gas fine regulating valve 12, and a turbine 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 line 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 production characteristics of the electrode material of the rechargeable battery 2 during the charging process.

[0098] The present invention conducts tests on the battery in-situ failure analysis system described in Example 3:

[0099] The experimental conditions are as follows: the positive electrode 2-1, electrolyte 2-2, and negative electrode 2-3 of the rechargeable battery 2 are LTO, solid electrolyte, and lithium indium alloy, respectively; the optical fiber probe 1 is located at the interface between the positive electrode 2-1 and the electrolyte 2-2; the constant current charge and discharge current is C / 10, and Ar is used as the inert gas.

[0100] The purpose of the test is to obtain the reflection spectrum diagram, the relationship diagram between voltage and strain, the relationship diagram between voltage and stress, and the relationship diagram between Δσ and SOC, so as to study the changes in stress of the battery during the charging and discharging process, which can effectively evaluate the battery capacity stability.

[0101] like Figure 4 As shown in the figure, it is the reflection spectrum obtained by the test. The initial λB Denoted as λ B,0 In the recorded spectrum, a single Bragg wavelength peak can be seen, which shifts to the right during charging and to the left during discharging. It can be inferred that under continuous cycling conditions, as charging and discharging proceed, the peak will repeatedly shift from right to left, thereby determining the mechanical reversibility of the battery.

[0102] like Figure 5 The figure shows the relationship between voltage and strain obtained from the test, which shows the change of strain with voltage during a charge and discharge cycle. As shown in the figure, when the battery is charging, the voltage continues to increase and Δλ also continues to increase. When the voltage reaches 1.3V, Δλ is 0.03. As the discharge progresses, Δλ gradually decreases, indicating that the battery has good cycle performance, small internal resistance, and lithium ions can be freely embedded / de-embedded.

[0103] like Figure 6 As shown in the figure, the relationship between voltage and stress obtained by the test is shown in the figure, which shows the change of stress with voltage. Figure 5 and Figure 6 The stress and strain in the Δσ show the same trend with voltage, as calculated based on Hooke's law. Within a single charge-discharge cycle, Δσ is less than 2 MPa, indicating good battery capacity retention. This example provides an effective method and research demonstration for successfully coupling an optical fiber stress testing system with a charge-discharge system through a battery model, enabling real-time monitoring of the stress and strain evolution of lithium batteries during charge and discharge, and intuitively obtaining numerical values ​​for electrode freshness / aging, which is crucial for improving lithium battery life and assessing battery safety.

[0104] like Figure 7 The graph below shows the relationship between Δσ and SOC obtained from the test, and the relationship between σ and SOC during the discharge process. During discharge, lithium ions are deintercalated from the negative electrode, pass through the separator, and enter the positive electrode. Electrons are then transferred from the external circuit to the positive electrode. During this process, significant changes in stress within the electrode will affect the normal transmission of lithium ions, potentially leading to lithium source loss, a decrease in lithium concentration, and a reduction in SOC. Therefore, monitoring changes in σ and SOC can effectively obtain information about the battery's capacity. As shown in the figure, when the battery's SOC is 100%, the battery pressure is 5.6 MPa. As discharge progresses, the stress gradually decreases with decreasing SOC. The fiber optic stress testing system can accurately determine the battery's state of charge, providing a basis for evaluating the battery's true capacity.

[0105] The present invention is not limited to the above-mentioned specific implementation methods. According to the above content, in accordance with the common technical knowledge and customary means in this field, without departing from the above-mentioned basic technical ideas of the present invention, the present invention can also make other various forms of equivalent modifications, replacements or changes, all of which fall within the scope of protection of the present invention.

Claims

1. A battery in-situ failure analysis system, characterized by: The invention is suitable for a rechargeable battery (2) having an optical fiber probe (1) disposed therein, wherein the optical fiber probe (1) contacts at least one of a positive electrode sheet (2-1), an electrolyte (2-2), and a negative electrode sheet (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 includes: a battery model, a charge and discharge test system, an optical fiber stress test system and a differential electrochemical mass spectrometry test system; The battery model comprises a battery model housing (7) provided with a positive electrode terminal (3), a negative electrode terminal (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 connected to the model sealed inner cavity (7a); and when the rechargeable battery (2) is installed in the battery model, the rechargeable battery (2) is fixed in the model sealed inner cavity (7a), and the positive electrode terminal (3) and the negative electrode terminal (4) are respectively electrically connected to the tabs on the positive electrode sheet (2-1) and the negative electrode sheet (2-3) of the rechargeable battery (2); The charge and discharge test system is capable of charging and discharging the rechargeable battery (2) installed in the battery model according to a preset charge and discharge program through the positive electrode terminal (3) and the negative electrode terminal (4); The optical fiber stress testing system is capable of introducing input light into the optical fiber probe (1) and detecting output light transmitted by the optical fiber probe (1) to obtain stress change characteristics of the electrode material of the rechargeable battery (2) during the charging process; The differential electrochemical mass spectrometry testing system is capable of injecting inert gas into the sealed inner cavity (7a) of the model through the gas inlet channel (5) and detecting the gas output from the gas outlet channel (6) to obtain the gas generation characteristics of the electrode material of the rechargeable battery (2) during the charging process.

2. The battery in-situ failure analysis system according to claim 1, characterized in that: The optical fiber probe (1) is arranged at the interface between the positive electrode piece (2-1) and the electrolyte (2-2), or at the interface between the negative electrode piece (2-3) and the electrolyte (2-2).

3. The battery in-situ failure analysis system according to claim 1, characterized in that: The battery model housing (7) is composed of a positive electrode side top cover (7-1) provided with the positive electrode terminal (3) and a negative electrode side base (7-2) provided with the negative electrode terminal (4); the positive electrode side top cover (7-1) and the negative electrode side base (7-2) are combined to form the model sealed inner cavity (7a).

4. The battery in-situ failure analysis system according to any one of claims 1 to 3, characterized in that: The optical fiber probe (1) is composed of an optical fiber core (101), a cladding (102), and a surface plasmon resonance layer (103) which are sequentially arranged from the inside to the outside, and the optical fiber core (101) is provided with an inclined optical Bragg grating (104); Furthermore, the optical fiber stress testing system comprises a light source device and a signal detection and processing device. The light source device is capable of introducing input light into the optical fiber probe (1), and the signal detection and processing device is capable of receiving output light transmitted by the optical fiber probe (1) and converting the output light into an electrical signal for detection, so as to obtain stress change characteristics of the electrode material of the rechargeable battery (2) during the charging process.

5. The battery in-situ failure analysis system according to any one of claims 1 to 3, characterized in that: The differential electrochemical mass spectrometry testing system comprises: the gas outlet channel (6) is connected to the inlet of a differential electrochemical mass spectrometer (14) through a vacuum system pipeline (8), and the vacuum system pipeline (8) is sequentially installed with a water-blocking and breathable membrane (9), a gas coarse regulating valve (10), a mechanical pump (11), a gas fine regulating valve (12), and a turbine pump (13) in the direction from the gas outlet channel (6) to the differential electrochemical mass spectrometer (14).

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

7. The battery in-situ failure analysis method according to claim 6, characterized in that: In step S4, the method of obtaining the stress change characteristics includes: Step S4-1: Based on the output light, obtain: the wavelength shift change Δλ of the optical fiber probe (1) during the charging process of the rechargeable battery (2) relative to the initial moment of the charging process B ; Step S4-2: according to the wavelength shift variation Δλ B , determining the stress change characteristics of the electrode material of the rechargeable battery (2) during the charging process.

8. The battery in-situ failure analysis method according to claim 7, characterized in that: The step S4-1 includes: Step S4-1a, obtaining a cladding mode signal or a surface plasmon resonance signal from the output light; wherein the method of obtaining the cladding mode signal is applicable to an optical fiber probe (1) consisting of an optical fiber core and a cladding sequentially arranged from the inside to the outside, and the method of obtaining the surface plasmon resonance signal is applicable to an optical fiber probe (1) consisting of an optical fiber core, a cladding, and a surface plasmon resonance layer sequentially arranged from the inside to the outside; Step S4-1b: Calculate the wavelength shift variation Δλ based on the cladding mode signal or surface plasmon resonance signal. B .

9. The battery in-situ failure analysis method according to claim 7 or 8, characterized in that: The optical fiber probe (1) uses an optical fiber with a light Bragg grating, and in step S4-2, the stress change characteristics of the electrode material of the rechargeable battery (2) during the charging process are calculated according to the following formula: λ B,0 =2n eff Λ[Formula 1] Δλ B = λ B - λ B,0 [Formula 2] Δλ B / λ B,0 =(1 - p e )ε[Formula Three] σ=Eε[Formula 4]where λ B,0 is the Bragg wavelength of the output light at the initial moment of the charging process of the rechargeable battery (2), n eff is the effective refractive index of the guided mode in the optical fiber probe (1), ∧ is the period of refractive index modulation; λ B is the Bragg wavelength of the output light during the charging process of the rechargeable battery (2), Δλ B is the wavelength shift variation of the optical fiber probe (1) during the charging process of the rechargeable battery (2) relative to the initial moment of the charging process; p e is the effective photoelastic coefficient, ε is the strain change occurring around the optical fiber probe (1); E is the Young's modulus; and σ is the stress change characteristic of the electrode material of the rechargeable battery (2) during the charging process.

10. The battery in-situ failure analysis method according to claim 6, characterized in that: In step S5, the gas generation characteristics are obtained by using the differential electrochemical mass spectrometry test system to detect the gas output from the gas outlet channel (6), 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) based on the measured mass-to-charge ratio, thereby obtaining the gas generation characteristics of the electrode material of the rechargeable battery (2) during the charging process.

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