CN114813408B - In-situ testing system for force-heat-electric coupling of battery separators under actual working conditions - Google Patents

Abstract

The invention discloses a battery diaphragm force-heat-electricity coupling in-situ test system under actual working conditions, which relates to the technical field of precision instruments and comprises a temperature control box, an environment module, a mechanical loading module and a multispectral-sound spectrum monitoring module. The environment module constructs electrochemical and low-temperature environment, the mechanical loading module carries out biaxial static-dynamic coupling loading on the cross diaphragm sample, and the multispectral-sound spectrum monitoring module comprises an optical imaging module, an infrared thermal imaging module and a sound emission module and is used for real-time monitoring of the loading process. According to the invention, the actual working condition of the diaphragm is simulated through the environment module, the mechanical loading module is used for loading, and the optical imaging module in the multispectral-acoustic spectrum monitoring module is used for dynamically observing the microstructure of the diaphragm; the infrared thermal imaging module identifies the temperature distribution of the diaphragm; the acoustic emission module is used for monitoring cracks and damages of the diaphragm. The invention provides instrument support for revealing the failure mechanism of the battery diaphragm and the microstructure evolution behavior of the battery diaphragm under the force-heat-electricity coupling.

Description

In-situ testing system for force-heat-electric coupling of battery separators under actual working conditions

Technical Field

The present invention relates to the field of precision instruments and the field of in-situ testing of battery materials, and in particular to an in-situ testing system for static-dynamic coupled loading of battery diaphragms that simulates actual working conditions and integrates multi-spectral-acoustic monitoring. The system integrates an optical microscope, an infrared thermal imager, and an acoustic emission nondestructive testing element, uses a three-level Peltier patch to create a low-temperature environment, and simulates an electrochemical environment through an electrolyte solution and positive and negative electrode materials. It can perform multi-spectral-acoustic in-situ monitoring of the failure process of biaxial static-dynamic coupled loading of the diaphragm under actual working conditions, and provides a testing instrument for understanding and revealing the failure mechanism of the diaphragm and improving the service reliability and stability of the battery.

Background technique

Since the 21st century, the energy shortage and environmental pollution behind the rapid economic development have brought great impact to the traditional automobile industry. Its high dependence on non-renewable energy and damage to the environment have limited its long-term application in the future. As one of the key development areas, new energy vehicles have innovated its power source and adopted batteries as a new power source for automobile driving, which has put forward higher requirements for battery technology. Among them, lithium-ion batteries with significant advantages such as high energy density, long cycle life and high charging efficiency are the mainstream batteries in electric vehicles. The frequent occurrence of fire and explosion accidents has limited its large-scale application and rapid popularization. Although after long-term experiments and explorations, the design of the on-board power battery system is relatively complete, most of them are installed in a solid shell for protection, and have passed a large number of industrial tests, but unpredictable traffic collision accidents and complex service working environments have caused lithium-ion batteries to fail due to abuse. Mechanical abuse such as extrusion, collision, and puncture, thermal abuse in low temperature environments, and electrical abuse such as overcharging and over-discharging can cause short circuits inside the battery, complex chemical reactions, and release of a large amount of heat and gas, causing thermal runaway, and then causing dangerous consequences such as fire and even explosion. The accelerated lithium intercalation and deposition in lithium-ion batteries under low temperature conditions can induce dendrite growth and development, piercing the diaphragm and causing a short circuit. As an important component of lithium-ion batteries, the failure mechanism of the diaphragm under the coupling of multiple physical fields such as cold environment and static-dynamic load has a significant impact on the safety and stability of lithium-ion batteries. In order to explore the performance of the diaphragm, it is more common to use instruments such as electron microscopes and XRD for static monitoring and analysis. However, this non-in-situ test can only obtain the microstructure and performance of the diaphragm before and after the test, and cannot dynamically observe the microstructural changes of the entire diaphragm failure process. Therefore, designing a diaphragm static-dynamic coupling loading device that can simulate actual working conditions and integrates an "optical-infrared-acoustic emission" multi-spectrum-acoustic spectrum in-situ monitoring instrument is of great significance for obtaining the real-time correlation between the diaphragm performance and the microstructural evolution behavior, and conducting research on the failure mechanism of battery diaphragms.

Summary of the invention

The purpose of the present invention is to design an in-situ testing system for the force-heat-electric coupling of a battery diaphragm under actual working conditions to solve the problems existing in the above-mentioned prior art. The "optical-infrared-acoustic emission" multi-spectrum-acoustic spectrum in-situ monitoring of the biaxial static-dynamic coupled loading process of the lithium-ion battery diaphragm under actual working conditions can be performed to observe the microstructural changes, global temperature gradients and local damage and failure of the diaphragm.

The above-mentioned purpose of the present invention is achieved by the following technical solutions:

A battery diaphragm force-heat-electric coupling in-situ testing system under actual working conditions, comprising a temperature control box 1, an environmental module 2, a mechanical loading module 3 and a multi-spectrum-acoustic monitoring module 4, wherein the temperature control box 1 is provided with the environmental module 2, the mechanical loading module 3 and the multi-spectrum-acoustic monitoring module 4, a cross-shaped diaphragm specimen 3.2 is installed in the mechanical loading module 3 for biaxial static-dynamic coupling loading, the environmental module 2 simulates the electrochemical environment and low temperature environment of the actual working condition of the diaphragm, the multi-spectrum-acoustic monitoring module comprises an optical imaging module 4, an infrared thermal imaging module 5 and an acoustic emission module 6, which are integrated into the temperature control box 1 via a cross bar 1.3.

The temperature control box 1 includes a temperature sensor 1.1, a guide rail 1.2, a cross bar 1.3, a display 1.4 and a temperature control box body 1.5. The display 1.4 is arranged on the outer side of the temperature control box body 1.5, and the guide rails 1.2 are symmetrically arranged on the two inner side surfaces of the temperature control box body 1.5. The cross bar 1.3 is slidably connected to the guide rail 1.2 through the card slots at both ends to achieve height adjustment. The multi-spectrum-acoustic spectrum monitoring module is integrated and installed directly above the environment module 2 in the temperature control box 1 through the cross bar 1.3.

The environmental module 2 includes an electrolyte environment box 2.1 and a low temperature environment box 2.2. The electrolyte environment box 2.1 includes an electrolyte box body 2.1.1 and an end cover 2.1.2. A quartz window is provided on the top of the box body for focusing each characterization instrument in the multi-spectral-acoustic spectrum monitoring module. The bottom of the end cover 2.1.2 is used to simulate the positive electrode of the battery, which is a conductive plate and a positive electrode material layer from top to bottom. The bottom of the electrolyte box body 2.1.1 is used to simulate the negative electrode of the battery, which is a conductive plate and a negative electrode material layer from bottom to top. The inside of the box body is filled with electrolyte solution, which is used to achieve electrochemical environment simulation of the actual working condition of the diaphragm. The low temperature environment box 2.2 includes a low temperature box body 2.2.1, a three-stage Peltier sheet 2.2.2 and a heat sink 2.2.3. The heat sink 2.2.3 is bonded to the three-stage Peltier sheet 2.2.2 by strong glue, and the array is arranged around and on the bottom of the low temperature box body 2.2.1.

The mechanical loading module 3 includes a force sensor 3.1, a cross-shaped diaphragm specimen 3.2, a dynamic loading unit 3.3, a cross-shaped specimen clamping unit 3.4, a static loading unit 3.5, a support pad 3.6, a fixture pad 3.7 and a base 3.8. The upper clamping body and the lower clamping body of the cross-shaped specimen clamping unit 3.4 are provided with a knurled structure on the contact surface with the diaphragm to increase the friction force and ensure stable clamping. The upper and lower clamping bodies are clamped by tightening screws and fixed on the fixture pad 3.7; the dynamic loading unit 3.3 is composed of four orthogonally arranged magnetostrictive actuators, and the flexible hinge 3.3.2 is respectively fastened to the fixture pad 3.7/force sensor 3.1 and the support pad 3.6 through a symmetrically arranged internal threaded hole structure. The magnetostrictive rod 3.3.1 driven by the magnetic coil Embedded in the flexible hinge 3.3.2; the static loading unit 3.5 is composed of two groups of orthogonally arranged left-right ball screw nut pairs, including left-right ball screws 3.5.1, ball nuts 3.5.4, fixed seats 3.5.2, motors 3.5.3 and support seats 3.5.5. The fixed seats 3.5.2 and support seats 3.5.5 are rigidly connected to the base 3.8 by threaded connections. The motor 3.5.3 is installed at the end of the fixed seat 3.5.2 to drive the left-right ball screw nut pairs. The ball nuts 3.5.4 are rigidly connected to the support pads 3.6 through nut seats.

The optical imaging module 4 includes a first bracket 4.1, an optical microscope 4.2 and an industrial camera 4.3. The tail end of the optical microscope 4.2 is threadedly connected to the industrial camera 4.3, clamped and fixed by a first clamping mechanism 4.1.5, and slidably connected to the cross bar 1.3 through a first displacement block 4.1.1. The first steering mechanism 4.1.3 adjusts the angle change.

The infrared thermal imaging module 5 comprises a second bracket 5.1, a fixing frame 5.2 and an infrared thermal imager 5.3. The infrared thermal imager 5.3 is embedded in the fixing frame 5.2 through a threaded connection, and is slidably connected to the crossbar 1.3 through a second displacement block 5.1.1. The second steering mechanism 5.1.3 adjusts the angle change.

The acoustic emission module 6 includes a third bracket 6.1, a precision displacement platform 6.2 and an acoustic emission sensor 6.3. The acoustic emission sensor 6.3 is bonded to the surface of the precision displacement platform 6.2 by strong glue, and the precision displacement platform 6.2 is rigidly connected to the third bracket 6.1 by threaded connection, and is slidably connected to the crossbar 1.3 by the third displacement block 6.1.2.

The multi-spectral-acoustic monitoring module performs "optical-infrared-acoustic emission" multi-spectral-acoustic in-situ monitoring based on optical microscopy imaging technology, infrared thermal imaging technology, and acoustic emission non-destructive testing technology, and is used to observe the microstructure of the failure micro-area, the global temperature gradient, and local damage failure of the cross-shaped diaphragm specimen 3.2 under static-dynamic coupled loading, and can cover the visual blind spots during the loading process to achieve all-round monitoring.

The mechanical loading module 3 realizes static-dynamic coupling loading of the cross-shaped diaphragm specimen 3.2. The left-right rotation ball screw nut pair in the static loading unit 3.5 is driven by the motor 3.5.3 to convert the left/right rotation into a synchronous and opposite large-stroke axial movement of the ball nut 3.5.4. The ball nut 3.5.4 drives the flexible hinge 3.3.2 rigidly connected to the support pad 3.6 to generate a bidirectional infinite tensile static load, which is suitable for loading superplastic diaphragm materials; the flexible hinge 3.3.2 in the dynamic loading unit 3.3 A diamond structure is adopted to convert the length change of the magnetostrictive rod 3.3.1 into its displacement in the orthogonal direction. The magnetostrictive rod 3.3.1 is always in a state of bearing compressive stress and produces periodic deformation under the action of the excitation magnetic field to achieve fatigue loading. The static loading unit 3.5 realizes synchronous reverse linear motion through a left-right rotating ball screw nut pair, and the dynamic loading unit 3.3 realizes the synchronization of fatigue loading through the orthogonal arrangement of magnetostrictive drivers in pairs, which is conducive to the central area of the cross-shaped diaphragm sample 3.2 always being in the center of the imaging field.

The cross-shaped diaphragm specimen 3.2 is provided with a notch in the central region to provide a non-uniform stress field, which serves as the region where crack initiation or fracture occurs during loading, so as to facilitate determination of the observation region of the multi-spectrum-acoustic spectrum monitoring module before the in-situ test begins.

The low-temperature box 2.2.1 in the environmental module 2 is arranged circumferentially around and the three-stage Peltier 2.2.2 arranged in an array on the bottom creates a uniform low-temperature environment to achieve global cooling. The electrolyte box 2.1.1 uses high thermal conductivity materials to achieve rapid cooling. The electrolyte solution is filled inside and together with the positive/negative electrode material layer simulates the electrochemical environment of the actual working condition of the diaphragm. The airtight structure of the temperature control box 1.5 maintains the stability of the low-temperature conditions and creates a constant low-temperature environment.

The beneficial effects of the present invention are as follows: a low-temperature environment and an electrochemical environment of the actual service conditions of the diaphragm are constructed through the environmental module, and dynamic fatigue testing and infinite tensile static loading of the diaphragm can be carried out by combining a flexible hinge with a ball screw transmission pair. Through the integration of an optical microscope, an infrared thermal imager and an acoustic emission sensor, "optical-infrared-acoustic emission" multi-spectrum-acoustic spectrum in-situ monitoring is realized, which can cover the visual blind area to achieve all-round observation, and provide a test instrument for understanding and revealing the failure mechanism of the diaphragm and improving the service reliability and stability of the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are used to provide further understanding of the present invention and constitute a part of this application. The illustrative examples of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

FIG1 is an axonometric view of the overall appearance of the present invention;

FIG2 is a front view of the overall appearance of the present invention;

FIG3 is an axonometric view of a temperature control box of the present invention;

FIG4 is a top view of an environmental module of the present invention;

FIG5 is an axonometric view of a mechanical loading module of the present invention;

FIG6 is a top view of a cross-shaped diaphragm sample of the present invention;

FIG7 is a schematic diagram of a cross-shaped sample clamping unit of the present invention;

FIG8 is a schematic diagram of a magnetostrictive actuator of the present invention;

FIG9 is a schematic diagram of a base of the present invention;

FIG10 is a schematic diagram of an optical imaging module of the present invention;

FIG11 is a schematic diagram of an infrared thermal imaging module of the present invention;

FIG. 12 is a schematic diagram of an acoustic emission module of the present invention.

In the figure: 1. Temperature control box; 1.1. Temperature sensor; 1.2. Guide rail; 1.3. Crossbar; 1.4. Display; 1.5. Temperature control box; 2. Environmental module; 2.1. Electrolyte environmental box; 2.1.1. Electrolyte box; 2.1.2. End cover; 2.2. Low temperature environmental box; 2.2.1. Low temperature box; 2.2.2. Three-stage Peltier patch; 2.2.3. Heat sink; 3. Mechanical loading module; 3.1. Force sensor; 3.2. Cross-shaped diaphragm specimen; 3.3. Dynamic loading unit; 3.3.1. Magnetostrictive rod; 3.3.2. Flexible hinge; 3.4. Cross-shaped specimen clamping unit; 3.5. Static 3.5.1, left-right rotating ball screw; 3.5.2, fixed seat; 3.5.3, motor; 3.5.4, ball nut; 3.5.5, support seat; 3.6, support pad; 3.7, fixture pad; 3.8, base; 4, optical imaging module; 4.1, first bracket; 4.1.1, first displacement block; 4.1.2, first hand wheel I; 4.1.3, first steering mechanism; 4.1.4, first hand wheel II; 4.1.5, first clamping mechanism; 4.2, optical microscope; 4.3. Industrial camera; 5. Infrared thermal imaging module; 5.1. Second bracket; 5.1.1. Second displacement block; 5.1.2. Second hand wheel I; 5.1.3. Second steering mechanism; 5.1.4. Second hand wheel II; 5.2. Fixed frame; 5.3. Infrared thermal imager; 6. Acoustic emission module; 6.1. Third bracket; 6.1.1. Third hand wheel; 6.1.2. Third displacement block; 6.2. Precision displacement stage; 6.3. Acoustic emission sensor.

Detailed ways

The details of the present invention and its specific implementation methods are further described below in conjunction with the accompanying drawings.

Referring to Figures 1 to 12: The present invention provides a battery diaphragm force-heat-electric coupling in-situ testing system under actual working conditions. The overall size of the system is 1320mm×1340mm×940mm, including a temperature control box, an environmental module, a mechanical loading module and a multi-spectral-acoustic monitoring module. The temperature control box is provided with an environmental module, a mechanical loading module and a multi-spectral-acoustic monitoring module. The cross-shaped diaphragm specimen is installed in the mechanical loading module for biaxial static-dynamic coupling loading. The environmental module simulates the electrochemical environment and low temperature environment of the actual working condition of the diaphragm. The multi-spectral-acoustic monitoring module includes an optical imaging module, an infrared thermal imaging module and an acoustic emission module.

In this embodiment, the temperature control box includes a temperature sensor, a guide rail, a cross bar, a display and a temperature control box body. The temperature control box body uses its closed structure to maintain a constant low temperature state. A temperature sensor is provided on the inside of the temperature control box body for real-time monitoring of changes in low temperature conditions. The display is arranged on the outer side of the temperature control box body, and the monitoring results of the optical microscope, infrared thermal imager and acoustic emission sensor are integrated into the display through the upper computer software; the guide rails are symmetrically arranged on the two sides inside the temperature control box body, and the cross bar is slidably connected to the guide rails through the slots at both ends to achieve height adjustment; the multi-spectrum-acoustic spectrum monitoring module is integrated and installed directly above the environmental module in the temperature control box through the cross bar.

In this embodiment, the environmental module includes an electrolyte environment box and a low temperature environment box. The electrolyte environment box includes an electrolyte box body and an end cover. A quartz window is provided on the top of the box body for focusing each characterization instrument in the multi-spectral-acoustic spectrum monitoring module. The bottom of the end cover is used to simulate the positive electrode of the battery, which is a conductive plate and a positive electrode material layer from top to bottom. The bottom of the electrolyte box body is used to simulate the negative electrode of the battery, which is a conductive plate and a negative electrode material layer from bottom to top. The inside of the box body is filled with electrolyte solution, which is used to realize the electrochemical environment simulation of the actual working condition of the diaphragm. The low temperature environment box includes a low temperature box body, a three-stage Peltier sheet and a heat sink. The heat sink and the three-stage Peltier sheet are bonded by strong glue. The circumferential layout around the low temperature box body and the bottom array layout create a low temperature environment to achieve global refrigeration. The electrolyte box body uses high thermal conductivity materials to accelerate heat conduction and achieve rapid cooling.

In this embodiment, the mechanical loading module includes a force sensor, a cross-shaped diaphragm specimen, a dynamic loading unit, a cross-shaped specimen clamping unit, a static loading unit, a support pad, a fixture pad and a base. A notch is set in the central area of the cross-shaped diaphragm specimen to provide a non-uniform stress field, which serves as the area where crack initiation or fracture occurs during the loading process, so as to facilitate the determination of the observation area of the multi-spectrum-acoustic spectrum monitoring module before the start of the in-situ test. The upper and lower clamping bodies of the cross-shaped specimen clamping unit are provided with a knurled structure on the contact surface with the diaphragm to increase the friction force and ensure stable clamping. The upper and lower clamping bodies are clamped by tightening screws and fixed on the fixture pad. The dynamic loading unit consists of four orthogonally arranged magnetostrictive actuators. The flexible hinge is fastened to the fixture pad/force sensor and the support pad through symmetrically arranged internal threaded hole structures. The magnetostrictive rod driven by the magnetic coil is embedded in the flexible hinge. The length change of the magnetostrictive rod is converted into its displacement in the orthogonal direction by utilizing the characteristics of the diamond structure. The magnetostrictive rod is always in a state of compressive stress and produces periodic deformation under the action of the excitation magnetic field to achieve fatigue loading. The static loading unit is composed of two groups of orthogonally arranged left-right ball screw nut pairs, including left-right ball screws, ball nuts, fixed seats, motors and support seats. The fixed seats and support seats are rigidly connected to the base through threaded connections to limit the axial movement of the screw. The motor is installed at the end of the fixed seat to drive the left-right ball screw nut pair, converting the left/right rotation into a pair of opposite large-stroke axial movements of the ball nuts. The ball nuts are rigidly connected to the support pads through the nut seat, driving the flexible hinges fastened to the support pads to generate infinitely tensile static loads, which are suitable for loading superplastic diaphragm materials. The dynamic loading unit realizes the synchronization of fatigue loading through the orthogonal arrangement of magnetostrictive drivers in pairs. The static loading unit realizes synchronous reverse linear motion through the left-right ball screw nut pair, which is conducive to the central area of the cross-shaped diaphragm specimen always being in the center of the imaging field of view. The static-dynamic coupled loading of the cross-shaped diaphragm specimen is realized through the combination of the two loading units, and fatigue tests, large-stroke tensile tests and their coupled test methods can be carried out.

In this embodiment, the optical imaging module includes a first bracket, an optical microscope and an industrial camera. The first bracket is composed of a first displacement block, a first hand wheel I, a first steering mechanism, a first hand wheel II and a first clamping mechanism. The tail end of the optical microscope is threadedly connected to the industrial camera, and a high depth of field continuously variable optical microscope lens is used. It is clamped and fixed by the radial fastening screws of the first clamping mechanism. The first steering mechanism is adjusted by the first hand wheel II to change the angle and lock the position. The first displacement block is slidably connected to the cross bar and locked by the first hand wheel I. The multi-degree-of-freedom movement and the zoom capability of the optical microscope itself can achieve accurate focusing and precise imaging of the central area of the cross-shaped diaphragm sample, and real-time observation of the microstructure of the diaphragm failure micro-area.

In this embodiment, the infrared thermal imaging module includes a second bracket, a fixed frame and an infrared thermal imager. The second bracket is composed of a second displacement block, a second hand wheel I, a second steering mechanism and a second hand wheel II. The infrared thermal imager is embedded in the fixed frame through a threaded connection. The second hand wheel II realizes the angle adjustment and position locking between it and the second steering mechanism. The second displacement block is slidably connected to the cross bar and locked by the second hand wheel I. The multi-degree-of-freedom movement can realize the global temperature gradient monitoring of the infrared thermal imager test area and the accurate identification of the abnormal point temperature.

In this embodiment, the acoustic emission module includes a third bracket, a precision displacement stage and an acoustic emission sensor, and the third bracket is composed of a third handwheel and a third displacement block. The acoustic emission sensor is bonded to the surface of the precision displacement stage by strong glue to achieve high-precision fine-tuning in the height direction. The precision displacement stage is rigidly connected to the third displacement block by a threaded connection, and the third displacement block is slidably connected to the cross bar and locked by the third handwheel. In this example, the acoustic emission sensor uses an optical fiber sensor to achieve non-contact measurement, monitor the defects and damage inside the diaphragm material in real time, and integrate the internal defect damage image of the diaphragm with the microstructure and global temperature on the display after analysis and processing.

In this embodiment, the multi-spectral-acoustic monitoring module performs "optical-infrared-acoustic emission" multi-spectral-acoustic in-situ monitoring based on optical microscopy imaging technology, infrared thermal imaging technology, and acoustic emission non-destructive testing technology. It can cover the visual blind spots during the loading process, and realize the "synchronous-same-situ" real-time in-situ monitoring of "micro-area microstructure-global temperature gradient-local damage and failure" when the battery diaphragm is subjected to static-dynamic loading under actual working conditions.

The battery diaphragm force-heat-electric coupling in-situ testing system under actual working conditions of this embodiment can create a low temperature and electrochemical environment, and can apply biaxial static-dynamic coupling loading to the cross-shaped diaphragm sample. Through the integration of optical imaging module, infrared thermal imaging module and acoustic emission module, the "optical-infrared-acoustic emission" multi-spectral-acoustic spectrum in-situ monitoring under actual working conditions can be performed, which can realize the real-time observation of the microstructure of the micro-area, the global temperature gradient and the local failure defects of the diaphragm. This embodiment provides instrument support for revealing the failure mechanism of the diaphragm and its microstructural evolution behavior under the coupling of force-heat-electric multi-physical fields.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (5)

1. A battery diaphragm force-heat-electric coupling in-situ testing system under actual working conditions, characterized in that it comprises a temperature control box (1), an environmental module (2), a mechanical loading module (3) and a multi-spectrum-acoustic monitoring module (4), wherein the temperature control box (1) is provided with the environmental module (2), the mechanical loading module (3) and the multi-spectrum-acoustic monitoring module (4), a cross-shaped diaphragm specimen (3.2) is installed in the mechanical loading module (3) for biaxial static-dynamic coupling loading, the environmental module (2) simulates the electrochemical environment and low temperature environment of the actual working condition of the diaphragm, and the multi-spectrum-acoustic monitoring module comprises an optical imaging module (4), an infrared thermal imaging module (5) and an acoustic emission module (6), which are integrated into the temperature control box (1) through a cross bar (1.3); The temperature control box (1) comprises a temperature sensor (1.1), a guide rail (1.2), a cross bar (1.3), a display (1.4) and a temperature control box body (1.5); the display (1.4) is arranged on the outer side of the temperature control box body (1.5); the guide rail (1.2) is symmetrically arranged on two side surfaces inside the temperature control box body (1.5); the cross bar (1.3) is slidably connected to the guide rail (1.2) via slots at both ends to achieve height adjustment; and the multi-spectrum-sound spectrum monitoring module is integrated and installed directly above the environment module (2) in the temperature control box (1) via the cross bar (1.3); The environmental module (2) comprises an electrolyte environmental box (2.1) and a low temperature environmental box (2.2). The electrolyte environmental box (2.1) comprises an electrolyte box body (2.1.1) and an end cover (2.1.2). A quartz window is provided on the top of the box body for focusing each characterization instrument in the multi-spectrum-acoustic spectrum monitoring module. The bottom surface of the end cover (2.1.2) is used to simulate the positive electrode of the battery, and from top to bottom are a conductive plate and a positive electrode material layer. The bottom of the electrolyte box body (2.1.1) is used to The simulated battery negative electrode includes, from bottom to top, a conductive plate and a negative electrode material layer, and the interior of the box is filled with an electrolyte solution, so as to realize the electrochemical environment simulation of the actual working condition of the diaphragm; the low temperature environment box (2.2) includes a low temperature box (2.2.1), a three-stage Peltier sheet (2.2.2) and a heat sink (2.2.3), and the heat sink (2.2.3) and the three-stage Peltier sheet (2.2.2) are bonded by strong glue, and the array is arranged around and on the bottom of the low temperature box (2.2.1); The mechanical loading module (3) comprises a force sensor (3.1), a cross-shaped diaphragm specimen (3.2), a dynamic loading unit (3.3), a cross-shaped specimen clamping unit (3.4), a static loading unit (3.5), a support pad (3.6), a fixture pad (3.7) and a base (3.8); the upper clamping body and the lower clamping body of the cross-shaped specimen clamping unit (3.4) are provided with a knurled structure on the contact surface with the diaphragm to increase the friction force and ensure stable clamping, and the upper and lower clamping bodies are clamped by tightening screws and fixed on the fixture pad (3.7); the dynamic loading unit (3.3) is composed of four orthogonally arranged magnetostrictive actuators, and the flexible hinge (3.3.2) is respectively connected to the fixture pad (3.7)/force sensor (3.8) through symmetrically arranged internal threaded hole structures. 1), the support pad (3.6) is tightly connected, and the magnetostrictive rod (3.3.1) driven by the magnetic coil is embedded in the flexible hinge (3.3.2); the static loading unit (3.5) is composed of two groups of orthogonally arranged left-right ball screw nut pairs, including left-right ball screws (3.5.1), ball nuts (3.5.4), fixed seats (3.5.2), motors (3.5.3) and support seats (3.5.5), the fixed seats (3.5.2) and the support seats (3.5.5) are rigidly connected to the base (3.8) by threaded connection, the motor (3.5.3) is installed at the end of the fixed seat (3.5.2) to drive the left-right ball screw nut pair, and the ball nuts (3.5.4) are transitionally rigidly connected to the support pad (3.6) through the nut seat; The optical imaging module (4) comprises a first bracket (4.1), an optical microscope (4.2) and an industrial camera (4.3); the tail end of the optical microscope (4.2) is threadedly connected to the industrial camera (4.3), clamped and fixed by a first clamping mechanism (4.1.5), slidably connected to the crossbar (1.3) by a first displacement block (4.1.1), and the first steering mechanism (4.1.3) adjusts the angle change; The infrared thermal imaging module (5) comprises a second bracket (5.1), a fixing frame (5.2) and an infrared thermal imager (5.3); the infrared thermal imager (5.3) is embedded in the fixing frame (5.2) through a threaded connection, and is slidably connected to the crossbar (1.3) through a second displacement block (5.1.1); and the second steering mechanism (5.1.3) adjusts the angle change; The acoustic emission module (6) comprises a third bracket (6.1), a precision displacement platform (6.2) and an acoustic emission sensor (6.3); the acoustic emission sensor (6.3) is bonded to the surface of the precision displacement platform (6.2) by means of strong glue, the precision displacement platform (6.2) is rigidly connected to the third bracket (6.1) by means of a threaded connection, and is slidably connected to the crossbar (1.3) by means of a third displacement block (6.1.2). 2. According to the actual working condition battery diaphragm force-heat-electric coupling in-situ testing system described in claim 1, it is characterized in that: the multi-spectrum-acoustic spectrum monitoring module performs "optical-infrared-acoustic emission" multi-spectrum-acoustic spectrum in-situ monitoring based on optical microscopy imaging technology, infrared thermal imaging technology, and acoustic emission non-destructive testing technology, which is used to observe the microstructure of the failure micro-area, the global temperature gradient and local damage failure of the cross-shaped diaphragm specimen (3.2) under static-dynamic coupling loading, and can cover the visual blind spots during the loading process to achieve all-round monitoring. 3. According to the actual working condition of the battery diaphragm force-heat-electric coupling in-situ testing system described in claim 1, it is characterized in that: the mechanical loading module (3) realizes static-dynamic coupling loading of the cross-shaped diaphragm specimen (3.2), and the left-right rotation ball screw nut pair in the static loading unit (3.5) is driven by the motor (3.5.3) to convert the left/right rotation into a synchronous and opposite large-stroke axial movement of the ball nut (3.5.4), and the flexible hinge (3.3.2) rigidly connected to the support pad (3.6) is driven by the ball nut (3.5.4) to generate a bidirectional infinite tensile static load, which is suitable for loading superplastic diaphragm materials; The flexible hinge (3.3.2) in the dynamic loading unit (3.3) adopts a diamond structure, and the length change of the magnetostrictive rod (3.3.1) is converted into the displacement in the orthogonal direction thereof. The magnetostrictive rod (3.3.1) is always in a state of bearing compressive stress, and produces periodic deformation under the action of the excitation magnetic field to achieve fatigue loading. The static loading unit (3.5) realizes synchronous reverse linear motion through a left-right rotating ball screw nut pair, and the dynamic loading unit (3.3) realizes the synchronization of fatigue loading through a pair of symmetrical orthogonal arrangement of magnetostrictive drivers, which is conducive to the central area of the cross-shaped diaphragm sample (3.2) always being in the center of the imaging field. 4. The battery diaphragm force-heat-electric coupling in-situ testing system under actual working conditions according to claim 1 is characterized in that: the cross-shaped diaphragm specimen (3.2) is provided with a notch in the central area to provide a non-uniform stress field, which serves as the area where crack initiation or fracture occurs during loading, so as to facilitate determination of the observation area of the multi-spectral-acoustic spectrum monitoring module before the in-situ test begins. 5. According to the in-situ test system for the force-heat-electric coupling of the battery diaphragm under actual working conditions as described in claim 1, it is characterized in that: the three-stage Peltier sheets (2.2.2) arranged circumferentially around the low-temperature box (2.2.1) in the environmental module (2) and arranged in an array on the bottom create a uniform low-temperature environment to achieve global cooling; the electrolyte box (2.1.1) adopts high thermal conductivity materials to achieve rapid cooling, and is filled with electrolyte solution inside, which together with the positive/negative electrode material layer simulates the electrochemical environment of the actual working condition of the diaphragm; the airtight structure of the temperature control box (1.5) maintains the stability of the low-temperature conditions and creates a constant low-temperature environment.