A multi-field in-situ strain characterization method and device for a pouch battery

Abstract

The embodiment of the application provides a kind of soft package battery's multiple field in-situ strain characterization method and device, with shear thickening electrolyte, soft package battery speckle mark surface is upwards, it is placed in the recess of in-situ observation platform, and positive and negative lug is connected to hard plate;Using intelligent temperature control device, the ambient temperature is adjusted to experimental temperature, infrared thermal imager is opened, and it is aligned with soft package battery;Fixed mechanical loading device is below the impact window of in-situ observation platform, and the adjustable power supply outside explosion-proof cover is connected with point device;Soft package battery is connected with battery test system and carries out charge-discharge test;CCD camera is connected with computer and is aligned with in-situ observation platform observation window, and starts shooting;Adjust the adjustable power supply parameter outside explosion-proof cover, and start mechanical loading device;Output the first mechanical behavior information and the second mechanical behavior information corresponding to the first time and the second time of soft package battery;According to the first mechanical behavior information and the second mechanical behavior information, the surface strain of soft package battery is obtained.

Description

Technical Field

[0001] This invention belongs to the field of battery in-situ characterization testing equipment and technology, and in particular relates to a multi-field in-situ strain characterization method and device for pouch batteries. Background Technology

[0002] Shear-thickened electrolytes are a novel type of safe battery material with unique mechanical response characteristics. They can transform from a liquid to a near-solid state under impact loads, effectively reducing the risk of thermal runaway in lithium-ion batteries caused by mechanical abuse. Studies show that parameters such as viscosity, critical shear rate, storage modulus, and loss modulus of shear-thickened electrolytes are significantly sensitive to temperature, and changes in electrical load also affect the thermal stability and electrochemical performance of batteries containing shear-thickened electrolytes. However, the influencing factors on the energy absorption buffer efficiency and electrochemical performance of batteries containing shear-thickened electrolytes under service conditions remain unclear. How to intuitively and quantitatively analyze the thermal stability, mechanical stability, and electrochemical characteristics of pouch cells containing shear-thickened electrolytes through experimental methods is crucial for the practical application of shear-thickened electrolytes.

[0003] To date, various experimental methods have been applied to the in-situ and non-in-situ characterization of shear-thickened electrolytes and their batteries. Current research on the safety and reliability of batteries containing shear-thickened electrolytes mainly focuses on characterizing thermal stability, mechanical properties, and electrochemical performance under single loads such as thermal, mechanical, and electrochemical loads. Examples include monitoring the open-circuit voltage stability of batteries containing shear-thickened electrolytes under impact conditions; indirectly characterizing the pressure distribution of batteries containing shear-thickened electrolytes under impact conditions using colorimetric pressure-sensitive paper; and capturing the morphological changes of batteries containing shear-thickened electrolytes under falling ball impact using high-speed cameras. Compared to traditional contact-based mechanical strain measurement methods, the emerging in-situ characterization technology based on digital image correlation (DIR) can provide real-time analysis support for the full-field strain of materials using non-contact measurement methods. A series of studies have utilized this technology to perform in-situ characterization of electrode strain during charging and discharging processes, such as using DIR to characterize the strain of graphite anodes caused by their own expansion.

[0004] The above characterization methods for shear-thickened electrolytes can reflect the shock resistance of electrolytes to a certain extent, but the following problems and challenges still exist: (1) Relying on single analysis methods such as voltage fluctuation and color distribution can only qualitatively assess the safety of the battery, and cannot quantitatively assess and classify the battery safety based on the changes in various safety characteristic parameters such as battery voltage, surface temperature, and surface strain during the test. (2) The service environment of batteries is complex, and in extreme cases, they are usually accompanied by multiple abuse conditions such as heat, force, and electrochemistry. Under the single-physical field test conditions provided in the existing research, it is not possible to systematically analyze the safety performance of batteries containing shear-thickened electrolytes under the influence of multiple factors of thermo-mechanical-electrochemical load. (3) If the test results under multiple single physical fields are combined to analyze the mechanical-chemical coupling behavior of the battery under multiple fields, it is not only necessary to have multiple batteries and multiple tests, which is time-consuming and laborious, but also cannot eliminate the differences between batteries in multiple tests, making it difficult to reflect the accuracy of the evolution of battery mechanical behavior under the coupling of various physical fields. Summary of the Invention

[0005] The purpose of this invention is to propose a multi-field in-situ strain characterization method and device for pouch batteries, which solves the problems of the current single method, discontinuous analysis results, and difficulty in quantification of safety performance analysis of batteries containing shear-thickened electrolytes under multi-physics field coupling.

[0006] To achieve the above objectives, the technical solution of this invention is implemented as follows:

[0007] In a first aspect, embodiments of the present invention provide a multi-field in-situ strain characterization method for pouch cells, comprising:

[0008] Place the pouch cell containing the shear-thickening electrolyte with the speckle markings facing upwards in the groove of the in-situ observation platform, and connect the positive and negative tabs to the rigid plate.

[0009] Use an intelligent temperature control device to adjust the ambient temperature to the experimental temperature, turn on the infrared thermal imager, and aim it at the soft-pack battery.

[0010] The fixed mechanical loading device is positioned below the impact window of the in-situ observation platform, and the jogging device is connected to an adjustable power supply outside the explosion-proof cover;

[0011] The soft-pack battery is connected to a battery testing system for charge and discharge testing.

[0012] Connect the CCD camera to the computer and align it with the observation window of the in-situ observation platform to start shooting;

[0013] Adjust the adjustable power parameters outside the explosion-proof cover and start the mechanical loading device;

[0014] Output the first mechanical behavior information and the second mechanical behavior information of the soft-pack battery at the first and second time points;

[0015] The surface strain of the pouch cell is obtained based on the first mechanical behavior information and the second mechanical behavior information.

[0016] Preferably, the first mechanical behavior information includes the strain contour map of the multi-field load at the first moment, the surface average strain, and the point strain, and the second mechanical behavior information includes the strain contour map of the multi-field load at the second moment, the surface average strain, and the point strain.

[0017] Preferably, the method further includes:

[0018] Point the CCD camera at the observation window of the in-situ observation platform, connect it to the computer and focus it until the speckle pattern on the surface of the pouch battery is clearly displayed, and turn on the CCD camera's fast capture mode.

[0019] Preferably, before aligning the speckle marking surface of the pouch cell containing the shear-thickening electrolyte upwards, the following steps are included:

[0020] A speckled pattern was uniformly sprayed onto the surface of a soft-pack battery containing a shear-thickening electrolyte using thermoplastic acrylic aerosol paint.

[0021] Secondly, embodiments of the present invention provide a multi-field in-situ strain characterization device for a pouch cell, comprising:

[0022] (1) A mechanical loading device, comprising an L-shaped base, a punch rod, a punch head, an adjustable power supply, and a jogging device; the L-shaped base has positioning holes, and the mechanical loading device is fixed on the vibration isolation platform by bolt connection; the stroke of the punch rod is adjustable, the punch head and the punch rod are threadedly connected, and the punch head is detachable; the adjustable power supply can adjust the impact force of the punch rod of the mechanical loading device.

[0023] (2) In-situ observation system, which includes an Aramis testing system, a CCD camera and an in-situ observation platform, to acquire the surface temperature, charge-discharge curve and mechanical behavior information of the soft-pack battery at any time or within any time period; the observation platform is fixed above the mechanical loading device by an upper rigid plate, a lower rigid plate, a long screw and a hexagonal nut, and the battery sample is placed between the rigid plates; both the in-situ observation platform and the mechanical loading device are placed inside an explosion-proof cover;

[0024] (3) Intelligent temperature control device, the intelligent temperature control device includes intelligent temperature control equipment and infrared thermal imager, the intelligent temperature control equipment is embedded in an explosion-proof cover;

[0025] (4) A battery testing system, wherein the battery testing system is connected to the positive and negative terminals of the lithium-ion battery via wires;

[0026] (5) Explosion-proof cover, the explosion-proof cover has a transparent observation port on the top, the transparent observation port provides an in-situ characterization observation channel for the battery; the explosion-proof cover has a wire outlet on the side for connecting the internal and external devices of the explosion-proof cover; a supplementary light is installed on the top corner of the explosion-proof cover.

[0027] Preferably, the upper rigid plate has a circular hole at its center as a CCD camera observation window, and the lower rigid plate has a circular hole at its center as an impact window. A shallow groove is formed at the center of the upper surface of the lower rigid plate to fix the soft-pack battery. The upper and lower rigid plates each have four through holes for the long screw to pass through. The long screw is a solid cylinder with threads at both the upper and lower ends and is marked with scale graduations. The upper and lower rigid plates are fixed to the upper end of the long screw with hexagonal nuts, and the lower end of the long screw is fixed to the vibration isolation platform with bolts.

[0028] This invention provides a multi-field in-situ strain characterization method for pouch batteries, comprising: uniformly spraying a speckle pattern onto the surface of a pouch battery containing a shear-thickening electrolyte using thermoplastic acrylic aerosol paint; adjusting the ambient temperature to the experimental temperature using an intelligent temperature control device; placing the pouch battery with the speckle surface facing upwards in a groove of an in-situ observation platform, with the positive and negative terminals connected to a rigid plate; turning on an infrared thermal imager, aiming it at the pouch battery, and recording the real-time surface temperature of the battery; fixing a mechanical loading device below the impact window of the in-situ observation platform, and connecting the jogging device to an adjustable power supply outside the explosion-proof cover; connecting the pouch battery to a battery testing system for charge-discharge testing; and outputting the surface temperature, charge-discharge curve, and mechanical behavior information of the pouch battery under different temperature fields, mechanical loads, and charge-discharge conditions. Compared with the prior art, this method has the following advantages:

[0029] 1) It can provide a test system that integrates thermal, mechanical and electrochemical field loading functions to simulate the complex working conditions of batteries during service;

[0030] 2) It can realize coupled data monitoring and quantitative analysis of multiple key parameters such as battery surface temperature, discharge voltage, and surface strain at any time point or time period during the entire testing process;

[0031] 3) This method can be applied to the study of thermo-mechanical-electrochemical coupling characteristics of soft-pack batteries containing shear-thickening electrolytes, and can flexibly adapt to the in-situ characterization needs of different types of coupling characteristics;

[0032] 4) This method is simple to operate, efficient, and has a wide range of applications, providing theoretical support for the design optimization of high-performance soft-pack batteries containing shear-thickening electrolytes and the safety evaluation of lithium-ion soft-pack batteries. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a multi-field in-situ strain characterization device for a soft-pack battery provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of a mechanical loading device provided in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the structure of an in-situ observation platform provided in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the structure of an explosion-proof cover provided in an embodiment of the present invention;

[0037] Figure 5 An in-situ voltage-surface average strain diagram of a pouch cell under multiple field effects provided in an embodiment of the present invention;

[0038] Figure 6 This is a strain contour plot of a pouch cell under multiple field conditions provided in an embodiment of the present invention.

[0039] Figure 7 This is a point strain diagram of a pouch cell under multiple field conditions provided in an embodiment of the present invention.

[0040] Figure 8 The strain contour plots of a pouch cell provided in this invention under multiple field conditions are shown in a proportional representation.

[0041] Explanation of reference numerals in the attached diagram: 1. Soft-pack battery; 2. Intelligent temperature control device; 3. Infrared thermal imager; 4. Mechanical loading device; 5. Explosion-proof cover; 6. Adjustable power supply; 7. Battery testing system; 8. CCD camera; 9. Aramis system; 10. Vibration isolation platform; 11. Supplemental light; 12. L-shaped base; 13. Punch; 14. Jog device; 15. Upper rigid plate; 16. Lower rigid plate; 17. Long screw; 18. Groove; 19. Transparent observation port; 20. Cable outlet; 21. Hexagonal nut; 22. Observation window; 23. Impact window; 24. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0044] Before providing a further detailed description of the present invention, the nouns and terms used in the embodiments of the present invention are explained, and the nouns and terms used in the embodiments of the present invention are subject to the following interpretations:

[0045] 1) Shear thickening: The viscosity of the system increases by orders of magnitude with the increase of shear rate or shear stress, exhibiting non-Newtonian fluid behavior;

[0046] 2) Speckle pattern: Random feature points are artificially created on the surface of the specimen for optical capture;

[0047] 3) Soft-pack battery containing shear-thickening electrolyte: The shear-thickening electrolyte is used as the ion transport medium to replace the conventional liquid electrolyte and assembled into a soft-pack battery;

[0048] 4) Digital image correlation method: A method to obtain the full-field displacement by calculating and processing speckle mark images on the surface of specimens in undeformed and deformed states;

[0049] 5) Mechanochemical coupling relationship: the relationship between battery surface strain and parameters such as discharge voltage during the same process;

[0050] 6) Strain: The proportion of deformation of a material relative to its initial state after being subjected to a force load;

[0051] 7) First mechanical behavior information: refers to the surface strain information of the soft pack battery recorded at the first moment during the entire process of the mechanical loading device's punch contacting the back of the soft pack from the upward movement to the downward movement away from the back of the soft pack battery;

[0052] 8) Second mechanical behavior information: refers to the surface strain information of the pouch battery recorded at the second moment during the entire process from the moment the punch of the mechanical loading device leaves the back of the pouch battery to the end of the shooting.

[0053] This invention provides a multi-field in-situ strain characterization method for pouch cells, including:

[0054] Place the pouch cell containing the shear-thickening electrolyte with the speckle markings facing upwards in the groove of the in-situ observation platform, and connect the positive and negative tabs to the rigid plate.

[0055] Use an intelligent temperature control device to adjust the ambient temperature to the experimental temperature, turn on the infrared thermal imager, and aim it at the soft-pack battery.

[0056] The fixed mechanical loading device is positioned below the impact window of the in-situ observation platform, and the jogging device is connected to an adjustable power supply outside the explosion-proof cover;

[0057] The soft-pack battery is connected to a battery testing system for charge and discharge testing.

[0058] Connect the CCD camera to the computer and align it with the observation window of the in-situ observation platform to start shooting;

[0059] Adjust the adjustable power parameters outside the explosion-proof cover and start the mechanical loading device;

[0060] Output the first mechanical behavior information and the second mechanical behavior information of the soft-pack battery at the first and second time points;

[0061] The surface strain of the pouch cell is obtained based on the first mechanical behavior information and the second mechanical behavior information.

[0062] It should be noted that the mechanical behavior information in this embodiment of the invention is the analysis of three processes: impact contact, impact process, and impact removal. The first moment and the second moment include any point in time or any time period of the impact contact, impact process, and impact removal mentioned above.

[0063] In one embodiment, the first mechanical behavior information includes the strain contour map of the multi-field load at a first moment, the surface average strain, and the point strain, and the second mechanical behavior information includes the strain contour map of the multi-field load at a second moment, the surface average strain, and the point strain.

[0064] In one embodiment, the method further includes:

[0065] Point the CCD camera at the observation window of the in-situ observation platform, connect it to the computer and focus it until the speckle pattern on the surface of the pouch battery is clearly displayed, and turn on the CCD camera's fast capture mode.

[0066] In one embodiment, before aligning the speckle marking surface of the pouch cell containing the shear-thickening electrolyte upwards, the following steps are included:

[0067] A speckled pattern was uniformly sprayed onto the surface of a shear-thickened electrolyte pouch battery using thermoplastic acrylic aerosol paint.

[0068] Secondly, embodiments of the present invention provide a multi-field in-situ strain characterization device for a pouch cell, comprising:

[0069] (1) A mechanical loading device, comprising an L-shaped base, a punch rod, a punch head, an adjustable power supply, and a jogging device; the L-shaped base has positioning holes, and the mechanical loading device is fixed on the vibration isolation platform by bolt connection; the stroke of the punch rod is adjustable, the punch head and the punch rod are threadedly connected, and the punch head is detachable; the adjustable power supply can adjust the impact force of the punch rod of the mechanical loading device.

[0070] (2) In-situ observation system, which includes an Aramis testing system, a CCD camera and an in-situ observation platform, to acquire the surface temperature, charge-discharge curve and mechanical behavior information of the soft-pack battery at any time or within any time period; the observation platform is fixed above the mechanical loading device by an upper rigid plate, a lower rigid plate, a long screw and a hexagonal nut, and the battery sample is placed between the rigid plates; both the in-situ observation platform and the mechanical loading device are placed inside an explosion-proof cover;

[0071] (3) Intelligent temperature control device, the intelligent temperature control device includes intelligent temperature control equipment and infrared thermal imager, the intelligent temperature control equipment is embedded in an explosion-proof cover;

[0072] (4) A battery testing system, wherein the battery testing system is connected to the positive and negative terminals of the lithium-ion battery via wires;

[0073] (5) Explosion-proof cover, the explosion-proof cover has a transparent observation port on the top, the transparent observation port provides an in-situ characterization observation channel for the battery; the explosion-proof cover has a wire outlet on the side for connecting the internal and external devices of the explosion-proof cover; a supplementary light is installed on the top corner of the explosion-proof cover.

[0074] In one embodiment, a circular hole is formed at the center of the upper rigid plate as an observation window for a CCD camera, and a circular hole is formed at the center of the lower rigid plate as an impact window. A shallow groove is formed at the center of the upper surface of the lower rigid plate to fix the soft-pack battery. The upper and lower rigid plates are each provided with four through holes for a long screw to pass through. The long screw is a solid cylinder with threads at both the upper and lower ends and is marked with scale graduations. The upper and lower rigid plates are fixed to the upper end of the long screw with hexagonal nuts, and the lower end of the long screw is fixed to the vibration isolation platform with bolts.

[0075] The specific embodiments of the present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the embodiments described herein.

[0076] Example 1

[0077] Battery under test: Shear-thickened electrolyte pouch cell

[0078] Device: such as Figure 1 As shown, four long screws of the in-situ observation platform are fixed on the vibration isolation platform, and the height of the in-situ observation platform is adjusted and fixed; the positive and negative terminals of the soft-pack battery are connected to the battery testing system and placed in the shallow groove on the upper surface of the lower rigid plate, and the upper and lower rigid plates are clamped by hexagonal bolts; the impact load device is fixed below the impact window of the lower rigid plate of the in-situ observation platform through the positioning hole of the L-shaped base; the CCD camera of the in-situ observation system is placed above the observation port of the in-situ observation platform and focused to clearly observe the speckle pattern on the battery surface.

[0079] Work process

[0080] Step 1: Assemble a pouch cell containing a shear-thickening electrolyte in a glove box with an argon atmosphere containing <0.1ppm of water and oxygen.

[0081] Step 2: Spray a speckled pattern of thermoplastic acrylic aerosol paint evenly onto the surface of the battery, and place it in a constant temperature drying oven for 8 hours;

[0082] Step 3: Place the pouch battery with the speckle side facing up in the shallow groove on the upper surface of the rigid plate under the in-situ observation platform, and connect the positive and negative terminals out of the rigid plate through wires, and fix the upper and lower rigid plates with nuts.

[0083] Step 4: Turn on the infrared thermal imager, aim it at the soft-pack battery, and record the real-time surface temperature of the battery;

[0084] Step 5: Fix the mechanical loading device directly below the impact window of the in-situ observation platform, and connect the jog device to the adjustable power supply outside the explosion-proof cover;

[0085] Step Six: Adjust the intelligent temperature control device to apply an ambient temperature of 40°C to the battery of the in-situ observation platform;

[0086] Step 7: At the fixed temperature mentioned above, the battery is subjected to a 5C charge-discharge test using a battery testing system, and the charge-discharge curve of the battery is recorded.

[0087] Step 8: Connect the CCD camera to the computer, align it with the observation port of the in-situ observation platform, adjust the focal length of the CCD camera until the speckle pattern on the surface of the soft-pack battery is clearly displayed, turn on the camera's fast capture mode, and collect digital image information of the speckle on the battery surface.

[0088] Step 9: Set the impact force to 16N by adjusting the adjustable power supply, start the jog device to apply a single impact load to the battery, and then turn off the camera capture mode.

[0089] Step 10: Using the Aramis testing system, the acquired digital image information is calculated and analyzed to obtain the full-process strain cloud map, average surface strain, and point strain of the pouch battery under multiple thermal / mechanical / electrochemical conditions, as well as the charge-discharge curves and continuous changes in surface temperature at different stages of battery operation. Based on the above information, the first and second mechanical behaviors of the pouch battery at the first and second moments under multiple loads are analyzed, including the force-electrochemical coupling relationship and thermal stability of the pouch battery.

[0090] Results analysis:

[0091] (1) Real-time thermo-mechanical-electric coupling analysis under multiple loads: The collected information is summarized and processed to obtain real-time data on the voltage, surface strain, and surface temperature of the shear-thickened electrolyte pouch cell at any time point or within any time period during the entire testing process. For example, see attached... Figure 5 As shown, the x-axis represents time, the left y-axis represents discharge voltage, and the right y-axis represents average surface strain. During the impact loading process (within 100ms, recording time 1.4-1.5s), deformation of the battery surface was observed in the shear-thickened electrolyte pouch battery. As the impact rod of the mechanical load device pressed against the back of the battery, the average surface strain gradually increased. At the same time, the discharge voltage of the battery decreased with the increase of the average surface strain, showing a negative linear correlation. The average strain on the surface of the pouch battery increased to 0.74% at a rate of 0.695% per second, while the voltage decreased to 3.114V at a rate of 0.3V per second. After the plunger reached its maximum stroke and began to descend (within 100ms, recording time 1.5-1.6s), the average strain on the battery surface gradually decreased with the removal of the load, recovering to 0.157%. Simultaneously, the discharge voltage of the pouch battery continued to decrease uniformly to 3.100V at a rate of 0.014V / s. During the recovery of the average strain on the pouch battery surface, the discharge voltage and the average surface strain showed a positive linear correlation. After the plunger was completely removed from the lower surface of the in-situ observation platform (recording time 1.6-12s), the average strain on the surface of the shear-thickened pouch battery slowly decreased to 0.135%, while the discharge voltage recovered to its original voltage plateau, with the rate of increase gradually slowing down until it stabilized at the initial discharge voltage plateau. This occurred at any point in time or during any time period.

[0092] (2) Multi-load in-situ strain contour plot analysis: The strain contour plots output in Example 1 above are selected from any time point at different stages (at impact contact, during impact, and after impact removal), as shown in the attached figure. Figure 6 As shown, during the impact loading process of the mechanical loading device, the shear-thickened electrolyte pouch battery exhibits significant strain in its central region. The cloud map shows a mesh-like strain that gradually develops from the impact center outwards, and the color of the mesh cloud map gradually deepens as the force is applied. After the impact rod reaches its maximum stroke and begins to descend, the mesh structure of the pouch battery's strain cloud map gradually fades in color from the edge towards the impact center, and finally the mesh strain structure disappears, essentially returning to its initial state. This result is consistent with the surface average strain curve result.

[0093] (3) Real-time strain analysis under multiple loads: Strain data at any point at the impact center was extracted from the DIC analysis area of ​​the strain cloud map output in Example 1 above, as shown in the attached figure. Figure 7As shown, the deformation evolution of the point under impact load is illustrated. The point strain depends on the selection of the analysis position on the electrode surface by the DIC system. The peak point strain at the selected position in Example 1 is 0.32%, which is less than the average surface strain (0.74%), but the overall trend and the time nodes of each stage are consistent with the average surface strain curve.

[0094] Example 2

[0095] Battery under test: Shear-thickened electrolyte pouch cell

[0096] Device: such as Figure 1 As shown, four long screws of the in-situ observation platform are fixed on the vibration isolation platform, and the height of the in-situ observation platform is adjusted and fixed; the positive and negative terminals of the soft-pack battery are connected to the battery testing system and placed in the shallow groove on the upper surface of the lower rigid plate, and the upper and lower rigid plates are clamped by hexagonal bolts; the impact load device is fixed below the impact window of the lower rigid plate of the in-situ observation platform through the positioning hole of the L-shaped base; the CCD camera of the in-situ observation system is placed above the observation port of the in-situ observation platform and focused to clearly observe the speckle pattern on the battery surface.

[0097] Work process

[0098] Step 1: Assemble a pouch cell containing a shear-thickening electrolyte in a glove box with an argon atmosphere containing <0.1ppm of water and oxygen.

[0099] Step 2: Spray a speckled pattern of thermoplastic acrylic aerosol paint evenly onto the surface of the battery, and place it in a constant temperature drying oven for 8 hours;

[0100] Step 3: Place the pouch battery with the speckle side facing up in the shallow groove on the upper surface of the rigid plate under the in-situ observation platform, and connect the positive and negative terminals out of the rigid plate through wires, and fix the upper and lower rigid plates with nuts.

[0101] Step 4: Turn on the infrared thermal imager, aim it at the soft-pack battery, and record the real-time surface temperature of the battery;

[0102] Step 5: Fix the mechanical loading device directly below the impact window of the in-situ observation platform, and connect the jog device to the adjustable power supply outside the explosion-proof cover;

[0103] Step Six: Adjust the intelligent temperature control device to apply an ambient temperature of 25°C to the battery of the in-situ observation platform;

[0104] Step 7: At the above fixed temperature, perform a charge-discharge test on the battery at 0.1C using a battery testing system, and record the charge-discharge curve of the battery;

[0105] Step 8: Connect the CCD camera to the computer, align it with the observation port of the in-situ observation platform, adjust the focal length of the CCD camera until the speckle pattern on the surface of the soft-pack battery is clearly displayed, turn on the camera's fast capture mode, and collect digital image information of the speckle on the battery surface.

[0106] Step 9: Set the impact force to 16N by adjusting the adjustable power supply, start the jog device to apply a single impact load to the battery, and then turn off the camera capture mode.

[0107] Step 10: Using the Aramis testing system, the acquired digital image information is calculated and analyzed to obtain the full-process strain cloud map, average surface strain, and point strain of the pouch battery under multiple thermal / mechanical / electrochemical conditions, as well as the charge-discharge curves and continuous changes in surface temperature at different stages of battery operation. Based on the above information, the first and second mechanical behaviors of the pouch battery at the first and second moments under multiple loads are analyzed, including the force-electrochemical coupling relationship and thermal stability of the pouch battery.

[0108] Results analysis:

[0109] (1) Real-time thermo-mechanical-electric coupling analysis under multiple loads: The collected information was summarized and processed to obtain real-time data on the voltage, surface strain, and surface temperature of the shear-thickening electrolyte pouch battery at any time point or time period during the entire test process. During the impact loading process, deformation of the battery surface was observed. As the impact rod of the mechanical load device pressed against the back of the battery, the average surface strain gradually increased. At the same time, the discharge voltage of the battery decreased with the increase of the average surface strain, showing a negative linear correlation. The average surface strain of the pouch battery increased to 0.45% at a rate of 0.407% per second, and the voltage decreased to 3.379V at a rate of 0.05V per second. After the impact rod reached its maximum stroke, it began to descend. The average surface strain of the battery gradually decreased with the removal of the load, recovering to 0.118%. The discharge voltage of the pouch battery continued to decrease at a uniform rate of 0.006V / s to 3.373V. During the recovery of the average strain on the surface of the soft-pack battery, the discharge voltage and the average surface strain are positively linearly correlated. After the punch is completely removed from the lower surface of the in-situ observation platform, the average strain on the surface of the shear-thickened soft-pack battery slowly decreases to 0.106%, and the discharge voltage recovers to the original voltage plateau, with the rate of increase gradually slowing down until it stabilizes at the initial discharge voltage plateau.

[0110] (2) Multi-load in-situ strain cloud map analysis: The strain cloud map output in Example 2 above selects the strain cloud map at any time point in different stages (at impact contact, during impact, and after impact removal). During the impact loading process of the mechanical loading device, the shear-thickened electrolyte soft-pack battery exhibits a certain degree of strain in the central region. The cloud map shows a mesh-like strain that gradually develops from the impact center to the surrounding area, and the color of the mesh cloud map gradually deepens with the force loading process. After the stroke of the impact rod reaches its maximum and begins to descend, the mesh structure of the soft-pack battery strain cloud map gradually fades in color from the edge towards the impact center, and finally the mesh strain structure disappears, basically returning to the initial state. This result is consistent with the surface average strain curve result.

[0111] (3) Real-time point strain analysis under multiple loads: The strain data of any point at the impact center was extracted from the strain cloud map DIC analysis area output in Example 2 above, showing the deformation evolution of the point under the impact load. The point strain depends on the selection of the analysis position on the electrode surface by the DIC system. The peak point strain at the selected position in Example 2 is 0.08%, which is less than the average surface strain (0.45%), but the overall trend and the time nodes of each stage are consistent with the average surface strain curve.

[0112] Example 3

[0113] Battery under test: Shear-thickened electrolyte pouch cell

[0114] Device: such as Figure 1 As shown, four long screws of the in-situ observation platform are fixed on the vibration isolation platform, and the height of the in-situ observation platform is adjusted and fixed; the positive and negative terminals of the soft-pack battery are connected to the battery testing system and placed in the shallow groove on the upper surface of the lower rigid plate, and the upper and lower rigid plates are clamped by hexagonal bolts; the impact load device is fixed below the impact window of the lower rigid plate of the in-situ observation platform through the positioning hole of the L-shaped base; the CCD camera of the in-situ observation system is placed above the observation port of the in-situ observation platform and focused to clearly observe the speckle pattern on the battery surface.

[0115] Work process

[0116] Step 1: Assemble a pouch cell containing a shear-thickening electrolyte in a glove box with an argon atmosphere containing <0.1ppm of water and oxygen.

[0117] Step 2: Spray a speckled pattern of thermoplastic acrylic aerosol paint evenly onto the surface of the battery, and place it in a constant temperature drying oven for 8 hours;

[0118] Step 3: Place the pouch battery with the speckle side facing up in the shallow groove on the upper surface of the rigid plate under the in-situ observation platform, and connect the positive and negative terminals out of the rigid plate through wires, and fix the upper and lower rigid plates with nuts.

[0119] Step 4: Turn on the infrared thermal imager, aim it at the soft-pack battery, and record the real-time surface temperature of the battery;

[0120] Step 5: Fix the mechanical loading device directly below the impact window of the in-situ observation platform, and connect the jog device to the adjustable power supply outside the explosion-proof cover;

[0121] Step Six: Adjust the intelligent temperature control device to apply an ambient temperature of 25°C to the battery of the in-situ observation platform;

[0122] Step 7: At the fixed temperature mentioned above, perform a charge-discharge test on the battery at 5C using a battery testing system, and record the charge-discharge curve of the battery.

[0123] Step 8: Connect the CCD camera to the computer, align it with the observation port of the in-situ observation platform, adjust the focal length of the CCD camera until the speckle pattern on the surface of the soft-pack battery is clearly displayed, turn on the camera's fast capture mode, and collect digital image information of the speckle on the battery surface.

[0124] Step 9: Set the impact force to 16N by adjusting the adjustable power supply, start the jog device to apply a single impact load to the battery, and then turn off the camera capture mode.

[0125] Step 10: Using the Aramis testing system, the acquired digital image information is calculated and analyzed to obtain the full-process strain cloud map, average surface strain, and point strain of the pouch battery under multiple thermal / mechanical / electrochemical conditions, as well as the charge-discharge curves and continuous changes in surface temperature at different stages of battery operation. Based on the above information, the first and second mechanical behaviors of the pouch battery at the first and second moments under multiple loads are analyzed, including the force-electrochemical coupling relationship and thermal stability of the pouch battery.

[0126] Results analysis:

[0127] (1) Real-time thermo-mechanical-electric coupling analysis under multiple loads: The collected information is summarized and processed to obtain real-time data on the voltage, surface strain, and surface temperature of the shear-thickened electrolyte pouch battery at any time point or within any time period during the entire test process. During the impact loading process, deformation of the battery surface was observed. As the impact rod of the mechanical load device squeezed the back of the battery, the average surface strain gradually increased. At the same time, the discharge voltage of the battery decreased with the increase of surface strain, showing a negative linear correlation. The average strain on the surface of the pouch battery increased to 0.46% at a rate of 0.409% per second, while the voltage decreased to 3.323V at a rate of 0.087V per second. After the plunger reached its maximum stroke, it began to descend. The average strain on the battery surface gradually decreased as the load was removed, recovering to 0.126%. The battery discharge voltage continued to decrease uniformly to 3.312V at a rate of 0.011V / s. During the recovery of the average strain on the pouch battery surface, the discharge voltage and the average surface strain showed a positive linear correlation. After the plunger was completely removed from the lower surface of the in-situ observation platform, the average strain on the shear-thickened pouch battery surface slowly decreased to 0.108%, while the discharge voltage recovered to the original voltage plateau, with the rate of increase gradually slowing down until it stabilized at the initial discharge voltage plateau.

[0128] (2) Multi-load in-situ strain cloud map analysis: The strain cloud map output in Example 3 above selects the strain cloud map at any time point in different stages (at impact contact, during impact, and after impact removal). During the impact loading process of the mechanical loading device, the shear-thickened electrolyte soft-pack battery exhibits a certain degree of strain in the central region. The cloud map shows a mesh-like strain that gradually develops from the impact center to the surrounding area, and the color of the mesh cloud map gradually deepens with the force loading process. After the stroke of the impact rod reaches its maximum and begins to descend, the mesh structure of the soft-pack battery strain cloud map gradually fades in color from the edge towards the impact center, and finally the mesh strain structure disappears, basically returning to the initial state. This result is consistent with the surface average strain curve result.

[0129] (3) Real-time point strain analysis under multiple loads: The strain data of any point at the impact center was extracted from the DIC analysis area of ​​the strain cloud map output in Example 3 above, showing the deformation evolution of the point under the impact load. The point strain depends on the selection of the analysis position on the electrode surface by the DIC system. The peak point strain at the selected position in Example 3 is 0.14%, which is less than the average surface strain (0.46%), but the overall trend and the time nodes of each stage are consistent with the average surface strain curve.

[0130] Example 4

[0131] Battery under test: Shear-thickened electrolyte pouch cell

[0132] Device: such as Figure 1As shown, four long screws of the in-situ observation platform are fixed on the vibration isolation platform, and the height of the in-situ observation platform is adjusted and fixed; the positive and negative terminals of the soft-pack battery are connected to the battery testing system and placed in the shallow groove on the upper surface of the lower rigid plate, and the upper and lower rigid plates are clamped by hexagonal bolts; the impact load device is fixed below the impact window of the lower rigid plate of the in-situ observation platform through the positioning hole of the L-shaped base; the CCD camera of the in-situ observation system is placed above the observation port of the in-situ observation platform and focused to clearly observe the speckle pattern on the battery surface.

[0133] Work process

[0134] Step 1: Assemble a pouch cell containing a shear-thickening electrolyte in a glove box with an argon atmosphere containing <0.1ppm of water and oxygen.

[0135] Step 2: Spray a speckled pattern of thermoplastic acrylic aerosol paint evenly onto the surface of the battery, and place it in a constant temperature drying oven for 8 hours;

[0136] Step 3: Place the pouch battery with the speckle side facing up in the shallow groove on the upper surface of the rigid plate under the in-situ observation platform, and connect the positive and negative terminals out of the rigid plate through wires, and fix the upper and lower rigid plates with nuts.

[0137] Step 4: Turn on the infrared thermal imager, aim it at the soft-pack battery, and record the real-time surface temperature of the battery;

[0138] Step 5: Fix the mechanical loading device directly below the impact window of the in-situ observation platform, and connect the jog device to the adjustable power supply outside the explosion-proof cover;

[0139] Step Six: Adjust the intelligent temperature control device to apply an ambient temperature of 40°C to the battery of the in-situ observation platform;

[0140] Step 7: At the fixed temperature mentioned above, perform a charge-discharge test on the battery at 0.1C using a battery testing system, and record the charge-discharge curve of the battery;

[0141] Step 8: Connect the CCD camera to the computer, align it with the observation port of the in-situ observation platform, adjust the focal length of the CCD camera until the speckle pattern on the surface of the soft-pack battery is clearly displayed, turn on the camera's fast capture mode, and collect digital image information of the speckle on the battery surface.

[0142] Step 9: Set the impact force to 16N by adjusting the adjustable power supply, start the jog device to apply a single impact load to the battery, and then turn off the camera capture mode.

[0143] Step 10: Using the Aramis testing system, the acquired digital image information is calculated and analyzed to obtain the full-process strain cloud map, average surface strain, and point strain of the pouch battery under multiple thermal / mechanical / electrochemical conditions, as well as the charge-discharge curves and continuous changes in surface temperature at different stages of battery operation. Based on the above information, the first and second mechanical behaviors of the pouch battery at the first and second moments under multiple loads are analyzed, including the force-electrochemical coupling relationship and thermal stability of the pouch battery.

[0144] Results analysis:

[0145] (1) Real-time thermo-mechanical-electric coupling analysis under multiple loads: The collected information was summarized and processed to obtain real-time data on the voltage, surface strain, and surface temperature of the shear-thickened electrolyte pouch battery at any time point or time period during the entire test process. During the impact loading process, deformation of the battery surface was observed. As the impact rod of the mechanical load device pressed against the back of the battery, the average surface strain gradually increased, while the battery discharge voltage decreased with the increase of strain, showing a negative linear correlation. The average surface strain of the pouch battery increased to 0.63% at a rate of 0.578% per second, and the voltage decreased to 3.335V at a rate of 0.075V per second. After the impact rod reached its maximum stroke, it began to descend. The average surface strain of the battery gradually decreased with the removal of the load, recovering to 0.148%, and the battery discharge voltage continued to decrease uniformly to 3.326V at a rate of 0.009V / s. During the recovery of the average strain on the surface of the soft-pack battery, the discharge voltage and the average surface strain are positively linearly correlated. After the punch is completely removed from the lower surface of the in-situ observation platform, the average strain on the surface of the shear-thickened soft-pack battery slowly decreases to 0.121%, and at the same time, the discharge voltage recovers to the original voltage platform, and the rate of increase gradually slows down until it stabilizes at the initial discharge voltage platform.

[0146] (2) Multi-load in-situ strain cloud map analysis: The strain cloud map output in Example 4 above selects the strain cloud map at any time point in different stages (at impact contact, during impact, and after impact removal). During the impact loading process of the mechanical loading device, the shear-thickened electrolyte pouch battery shows obvious strain in the central region. The cloud map shows a mesh strain that gradually develops from the impact center to the surrounding area, and the color of the mesh cloud map gradually deepens with the force loading process. After the stroke of the impact rod reaches its maximum and begins to descend, the mesh structure of the pouch battery strain cloud map gradually fades in color from the edge to the impact center. Finally, the mesh strain structure disappears and basically returns to the initial state. This result is consistent with the surface average strain curve result.

[0147] (3) Real-time point strain analysis under multiple loads: The strain data of any point at the impact center was extracted from the DIC analysis area of ​​the strain cloud map output in Example 4 above, showing the deformation evolution of the point under the impact load. The point strain depends on the selection of the analysis position on the electrode surface by the DIC system. The peak point strain at the selected position in Example 4 is 0.25%, which is less than the average surface strain (0.63%), but the overall trend and the time nodes of each stage are consistent with the average surface strain curve.

[0148] First moment voltage fluctuation Surface average strain Example 1 -0.314V +0.74％ Example 2 -0.056V +0.45％ Example 3 -0.098V +0.47％ Example 4 -0.084V +0.63％ Comparative Example 1 -2.402V /

[0149] Table 1

[0150] Second moment voltage fluctuation Surface average strain Example 1 Gradually recover to the initial voltage plateau Gradually recovered to 0.135%. Example 2 Gradually recover to the initial voltage plateau Gradually recovered to 0.106%. Example 3 Gradually recover to the initial voltage plateau Gradually recovered to 0.108%. Example 4 Gradually recover to the initial voltage plateau Gradually recovered to 0.121%. Comparative Example 1 Rapidly reduced to 0V /

[0151] Table 2

[0152] See Tables 1 and 2 above for results analysis:

[0153] (1) Examples 2-4 lack the influence of at least one physical field compared to the test conditions in Example 1. Analysis of the data shows that the fluctuations in data such as voltage and average surface strain of the pouch battery, lacking at least one physical field, cannot be obtained by simply superimposing the data to achieve test results involving multiple physical fields. For example, compared to Examples 1 and 3, increasing the battery charge / discharge rate also affects the voltage fluctuation of the pouch battery under the same impact force; the higher the charge / discharge rate, the greater the voltage fluctuation under the impact load. Compared to Examples 1 and 4, the introduction of a temperature field directly affects the protective effect of the shear-thickening electrolyte. Specifically, the average surface strain of the battery increases with the increase of the test environment temperature, and this deformation process is accompanied by varying degrees of voltage drop and surface temperature rise.

[0154] (2) Based on the analysis of Example 2, Example 3 showed a voltage degradation of 0.042V and an increase in average surface strain of 0.02% compared to Example 2. Example 4 showed a voltage degradation of 0.028V and an increase in average surface strain of 0.18% compared to Example 2. The test conditions of Example 3 and Example 4 should be superimposed to those of Example 1. However, the test results of Example 1 showed a voltage degradation of 0.258V and an increase in average surface strain of 0.29% compared to Example 2. This indicates that superimposing the test results of a single field to analyze the performance of the battery under complex operating conditions is unreliable. The results of this thermo-mechanical-electrochemical coupling in Example 1 are more accurate, verifying the superiority of the multi-field in-situ strain characterization method.

[0155] (3) The superposition of test conditions in Examples 3 and 4 means that the larger load among the same external loads is taken as the test condition. Examples 1-4 can capture the fluctuations of voltage, surface strain and surface temperature data within any test time period, and continuously observe the working state of the battery under multiple loads.

[0156] Comparative Example 1

[0157] Battery under test: Conventional liquid electrolyte pouch battery

[0158] Device: such as Figure 1 As shown, four long screws of the in-situ observation platform are fixed on the vibration isolation platform, and the height of the in-situ observation platform is adjusted and fixed; the positive and negative terminals of the soft-pack battery are connected to the battery testing system and placed in the shallow groove on the upper surface of the lower rigid plate, and the upper and lower rigid plates are clamped by hexagonal bolts; the impact load device is fixed below the impact window of the lower rigid plate of the in-situ observation platform through the positioning hole of the L-shaped base; the CCD camera of the in-situ observation system is placed above the observation port of the in-situ observation platform and focused to clearly observe the speckle pattern on the battery surface.

[0159] Work process

[0160] Step 1: Assemble a pouch cell containing a conventional liquid electrolyte in a glove box with an argon atmosphere containing <0.1ppm of water and oxygen.

[0161] Step 2: Spray a speckled pattern of thermoplastic acrylic aerosol paint evenly onto the surface of the battery, and place it in a constant temperature drying oven for 8 hours;

[0162] Step 3: Place the pouch battery with the speckle side facing up in the shallow groove on the upper surface of the rigid plate under the in-situ observation platform, and connect the positive and negative terminals out of the rigid plate through wires, and fix the upper and lower rigid plates with nuts.

[0163] Step 4: Turn on the infrared thermal imager, aim it at the soft-pack battery, and record the real-time surface temperature of the battery;

[0164] Step 5: Fix the mechanical loading device directly below the impact window of the in-situ observation platform, and connect the jog device to the adjustable power supply outside the explosion-proof cover;

[0165] Step Six: Adjust the intelligent temperature control device to apply an ambient temperature of 40°C to the battery of the in-situ observation platform;

[0166] Step 7: At the fixed temperature mentioned above, perform a charge-discharge test on the battery at 5C using a battery testing system, and record the charge-discharge curve of the battery.

[0167] Step 8: Connect the CCD camera to the computer, align it with the observation port of the in-situ observation platform, adjust the focal length of the CCD camera until the speckle pattern on the surface of the soft-pack battery is clearly displayed, turn on the camera's fast capture mode, and collect digital image information of the speckle on the battery surface.

[0168] Step 9: Set the impact force to 16N by adjusting the adjustable power supply, start the jog device to apply a single impact load to the battery, and then turn off the camera capture mode.

[0169] Step 10: Using the Aramis testing system, the acquired digital image information is calculated and analyzed to obtain the full-process strain cloud map, average surface strain, and point strain of the pouch battery under multiple thermal / mechanical / electrochemical conditions, as well as the charge-discharge curves and continuous changes in surface temperature at different stages of battery operation. Based on the above information, the first and second mechanical behaviors of the pouch battery at the first and second moments under multiple loads are analyzed, including the force-electrochemical coupling relationship and thermal stability of the pouch battery.

[0170] Results analysis:

[0171] (1) Real-time thermo-mechanical-electric coupling analysis under multiple loads: The collected information is summarized and processed to obtain real-time data on the voltage, surface strain, and surface temperature of the conventional liquid electrolyte pouch battery at any time point or time period during the entire test process. During the impact loading process, the conventional liquid electrolyte pouch battery was observed to undergo significant surface deformation. As the impact rod of the mechanical load device pressed against the back of the battery, the average surface strain gradually increased, and the discharge voltage of the battery decreased with the increase of surface strain, showing a negative linear correlation. After the impact rod reached its maximum stroke, the deformation of the pouch battery was significantly greater than that of the shear-thickened electrolyte pouch battery. The speckle displacement distance on the surface of the conventional liquid electrolyte pouch battery exceeded the capture range of the CCD camera, making it impossible to obtain an accurate average surface strain of the battery. During the entire process from the impact rod contacting the back of the pouch battery to its removal from the back of the battery, the pouch battery voltage decreased to 1V at a rate of 1.201V per second. During the entire process from the impact rod being completely removed from the underside of the original observation platform to the end of the shooting, the discharge voltage of the pouch battery rapidly decreased to 0V, indicating that the battery had a short circuit.

[0172] (2) Multi-load in-situ strain cloud map analysis: The strain cloud map output by Comparative Example 1 above selects strain cloud maps at any time point in different stages (at impact contact, during impact, and after impact removal). During the impact loading process of the mechanical loading device, the shear-thickened electrolyte pouch battery shows a large area of ​​strain loss in the central region, and the cloud map is incomplete; after the stroke of the impact rod reaches its maximum and begins to descend until it leaves the back of the pouch battery, the strain cloud map of the pouch battery shows a slight decrease in strain in the colored area, but the area of ​​strain loss remains basically unchanged;

[0173] (3) Real-time point strain analysis under multiple loads: Strain data at the impact center cannot be extracted from the strain cloud map output in Comparative Example 1 in the DIC analysis area. Point strain depends on the DIC system's selection of the analysis location on the electrode surface. Due to the excessive strain at the impact center of the conventional liquid electrolyte pouch battery, the strain cloud map shows too many missing points in the speckle pattern, making point strain analysis impossible for conventional liquid electrolyte pouch batteries. These results indicate that conventional liquid electrolyte pouch batteries are not suitable for this multi-field in-situ strain characterization method and device.

[0174] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and scope of the present invention are included within the scope of protection of the present invention.

Claims

1. A multi-field in-situ strain characterization method for pouch cells, characterized in that, include: Place the pouch cell containing the shear-thickening electrolyte with the speckle markings facing upwards in the groove of the in-situ observation platform, and connect the positive and negative tabs to the rigid plate. Use an intelligent temperature control device to adjust the ambient temperature to the experimental temperature, turn on the infrared thermal imager, and aim it at the soft-pack battery. The fixed mechanical loading device is positioned below the impact window of the in-situ observation platform, and the jogging device is connected to an adjustable power supply outside the explosion-proof cover; The soft-pack battery is connected to a battery testing system for charge and discharge testing. Connect the CCD camera to the computer and align it with the observation window of the in-situ observation platform to start shooting; Adjust the adjustable power parameters outside the explosion-proof cover and start the mechanical loading device; Output the first mechanical behavior information of the pouch battery at the first time point, and output the second mechanical behavior information of the pouch battery at the second time point; The surface strain of the pouch cell is obtained based on the first mechanical behavior information and the second mechanical behavior information. The first mechanical behavior information includes the strain cloud map of the multi-field load at the first moment, the average surface strain, and the point strain. The second mechanical behavior information includes the strain cloud map of the multi-field load at the second moment, the average surface strain, and the point strain.

2. The multi-field in-situ strain characterization method for soft-pack batteries according to claim 1, characterized in that, The method further includes: Point the CCD camera at the observation window of the in-situ observation platform, connect it to the computer and focus it until the speckle pattern on the surface of the pouch battery is clearly displayed, and turn on the CCD camera's fast capture mode.

3. The multi-field in-situ strain characterization method for soft-pack batteries according to claim 2, characterized in that, Before aligning the speckle marking surface of the pouch cell containing the shear-thickening electrolyte upwards, the process includes: A speckled pattern was uniformly sprayed onto the surface of a soft-pack battery containing a shear-thickening electrolyte using thermoplastic acrylic aerosol paint.

4. A multi-field in-situ strain characterization device for a pouch cell based on the multi-field in-situ strain characterization method for pouch cells according to claims 1 to 3, characterized in that, include: (1) A mechanical loading device, comprising an L-shaped base, a punch rod, a punch head, an adjustable power supply, and a jogging device; the L-shaped base has positioning holes, and the mechanical loading device is fixed on the vibration isolation platform by bolt connection; the stroke of the punch rod is adjustable, the punch head and the punch rod are threadedly connected, and the punch head is detachable; the adjustable power supply can adjust the impact force of the punch rod of the mechanical loading device. (2) In-situ observation system, which includes an Aramis testing system, a CCD camera and an in-situ observation platform, to acquire the surface temperature, charge-discharge curve and mechanical behavior information of the soft-pack battery at any time or within any time period; the observation platform is fixed above the mechanical loading device by an upper rigid plate, a lower rigid plate, a long screw and a hexagonal nut, and the battery sample is placed between the rigid plates; both the in-situ observation platform and the mechanical loading device are placed inside an explosion-proof cover; (3) Intelligent temperature control device, the intelligent temperature control device includes intelligent temperature control equipment and infrared thermal imager, the intelligent temperature control equipment being embedded in an explosion-proof cover; (4) A battery testing system, wherein the battery testing system is connected to the positive and negative terminals of the lithium-ion battery via wires; (5) Explosion-proof cover, wherein a transparent observation port is opened on the top of the explosion-proof cover, and the transparent observation port provides an in-situ characterization observation channel for the battery; a wire outlet is provided on the side of the explosion-proof cover for connecting the internal and external devices of the explosion-proof cover; and a supplementary light is installed on the top corner of the explosion-proof cover.

5. The multi-field in-situ strain characterization device for soft-pack batteries according to claim 4, characterized in that, The upper rigid plate has a circular hole at its center as a CCD camera observation window, and the lower rigid plate has a circular hole at its center as an impact window. A shallow groove is formed at the center of the upper surface of the lower rigid plate to fix the soft-pack battery. The upper and lower rigid plates each have four through holes for the long screw to pass through. The long screw is a solid cylinder with threads at both the upper and lower ends and is marked with scale graduations. The upper and lower rigid plates are fixed to the upper end of the long screw with hexagonal nuts, and the lower end of the long screw is fixed to the vibration isolation platform with bolts.

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