Lithium battery internal structure integrity device based on vibration detection

Abstract

The utility model relates to a lithium battery internal structure integrity device based on vibration detection, the device comprises a test part, a positioning part and a protection part, the test part is composed of a test board, a base, a pillar, a cushioning pad, a vibration motor and a vibration sensor, the vibration motor adopts a linear vibration motor (50-500Hz) to drive the test board to vibrate, and the positioning part is arranged on the base. The cushioning pad is made of 8-15mm natural rubber so as to isolate external interference; the positioning part realizes self-adaptive fixation of the battery through an air cylinder and a positioning rubber block on the door frame type bracket; and the protection part adopts an electric push rod to drive a 8-12mm silica gel protection pad, so that the vibration displacement of the battery is prevented. According to the device, battery feedback signals are collected in real time through broadband vibration, the problems of looseness, breakage and the like in the battery can be accurately detected in combination with dynamic anti-interference design, and the device has the advantages of dynamic detection, self-adaptive positioning, high reliability and integration and is suitable for the field of lithium battery production and safety evaluation.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of lithium battery detection, especially a lithium battery internal structure integrity device based on vibration detection. BACKGROUND

[0002] Lithium ion batteries have been widely used in new energy vehicles, aerospace and portable electronic devices due to their high energy density and long cycle life. However, during transportation and use, the batteries are often in a complex vibration environment, which may cause problems such as a decrease in the bonding force between the internal electrode material and the current collector, a slight damage to the separator, or a shedding of active material, and in severe cases, a heat runaway risk. In the prior art, the detection of the internal structure integrity of lithium batteries mainly relies on offline detection methods such as X-ray diffraction or electron microscope analysis, but such methods require the battery to be disassembled or placed in a static environment, making it difficult to reflect the real-time changes in the structure during dynamic vibration.

[0003] Currently, some studies attempt to simulate the transportation vibration environment using a vibration table and then analyze the internal structure of the battery using X-ray diffraction technology. However, this method has significant limitations: first, the vibration table usually uses a single frequency or a preset vibration mode, which cannot truly reproduce the randomly changing vibration conditions in actual scenarios; second, offline detection cannot capture the material self-repair phenomenon (such as the dynamic recovery of electrolyte infiltration of the separator) during vibration; in addition, the X-ray diffraction equipment is costly and requires a complex sample preparation process, making it difficult to achieve rapid detection. The vibration test tool in the prior art can adapt to different battery sizes, but it does not solve the dynamic and real-time problems of the detection method itself.

[0004] Therefore, it is a technical problem for those skilled in the art to develop a detection device that can monitor the internal structure integrity of the battery in real time during vibration to compensate for the lack of dynamic response capability of traditional offline detection methods and provide a more reliable technical means for lithium battery safety evaluation. UTILITY MODEL CONTENTS

[0005] To solve the problems in the background art, the utility model develops a lithium battery internal structure integrity device based on vibration detection, aiming to realize the detection of the internal integrity of the lithium battery through vibration. The device includes a test part, which includes a test table, the test table is a rectangular flat plate, the lower part of the test table is provided with a base, the corners of the four sides of the base are respectively provided with support columns, the upper part of the support columns is provided with a shock-absorbing pad, the test table is arranged above the shock-absorbing pad, the lower part of the test table is provided with a vibration motor, the middle part of the test table is provided with a circular hole, and a vibration sensor is arranged in the circular hole.

[0006] The test table is used for placing the lithium battery to be tested, the vibration motor drives the whole test table to vibrate through its vibration, so as to realize the vibration of the detected object on the test table, the vibration sensor is arranged at the center of the test table and is used for detecting the condition of the detected object, and the shock-absorbing pads arranged at the four corners of the test table are used for arranging the test table on a flexible support, so as to realize the vibration experiment of the test table and filter part of the resonance.

[0007] Further, the vibration motor adopts a linear vibration motor, and the vibration frequency is 50-500 Hz.

[0008] The vibration motor has a wide frequency range and can cover the typical resonance frequency of the internal structure of the lithium battery, the amplitude is stable and adjustable, the vibration intensity can be accurately adjusted by controlling the current or voltage, and meanwhile, the vibration motor is small in size and light in weight and is convenient to integrate under the test table. The vibration motor is suitable for scenes requiring wide-frequency vibration and high-precision detection, and is especially suitable for analyzing the loosening or fracture of the internal fine structure of the battery. The resonance frequency of the internal structure of the lithium battery (such as the electrode and the diaphragm) is usually between 50-500 Hz, so the vibration frequency of the vibration motor is selected as 50-500 Hz.

[0009] Further, the shock-absorbing pad is made of natural rubber with a thickness of 8-15 mm.

[0010] The elastic modulus of the natural rubber is 1-10 MPa, which is much lower than that of the metal support structure, and can significantly reduce the vibration transmission rate. The high damping characteristic (loss factor 0.1-0.3) of the natural rubber can quickly dissipate vibration energy and avoid resonance between the test table and the support column. The natural frequency of the natural rubber can be adjusted to 5-10 Hz by adjusting the thickness, for example, when the thickness of the shock-absorbing pad is 10 mm, the weight of the test table 11 is <50 kg, and according to the frequency matching calculation formula: , and the working frequency of the linear vibration motor is 50-500 Hz, which meets the 1 / 3 frequency isolation principle (i.e. the equipment frequency is greater than 3 times the natural frequency), and ensures that the isolation efficiency is >90%. If the mass of the test table is <50 kg (such as 30 kg) and the thickness is 8 mm, the natural frequency is approximately 8 Hz, which still meets the isolation requirement. If higher isolation efficiency is required, the thickness of 15 mm can reduce the natural frequency to 5 Hz, and the isolation efficiency is increased to more than 95%. The allowable compression strain of the natural rubber is 20%, that is, the 8 mm thick pad allows a maximum compression of 1.6 mm, and the amplitude of the motor is usually ≤0.5 mm, so the safety factor is 3.2, which is higher than the recommended safety factor of 2.0. In actual vibration, the dynamic stiffness of the rubber will increase with the increase of the amplitude, but the thickness of 8-15 mm provides enough nonlinear buffer space to avoid rigid contact.

[0011] Further, the device further comprises a positioning part, the positioning part comprises two vertical frames, a horizontal frame is arranged between the vertical frames, the vertical frames and the horizontal frame form a door frame type support arranged on the test table, a cylinder is arranged on the upper part of the middle of the horizontal frame, the working part of the cylinder penetrates through the horizontal frame, a positioning rubber block is arranged on the lower end of the working part of the cylinder, and the positioning rubber block is controlled to be lowered by the cylinder to realize positioning of the detected lithium battery.

[0012] Further, the device further comprises a protection part, the protection part is arranged on the left and right sides of the test table, the protection part comprises a fixing frame, the fixing frame is arranged on the two sides of the test table, a plurality of push rods are arranged inward on the side of the fixing frame, and a protection pad is arranged at the front end of the push rod. The protection part is used for placing the detected lithium battery to prevent the lithium battery from deviating or falling during vibration.

[0013] Further, the protection pad is made of silica gel material with a thickness of 8-12 mm.

[0014] The silica gel can maintain elasticity in the range of -60 DEG C to 200 DEG C, and is suitable for the detection requirements of lithium battery thermal abuse test or high-temperature environment. Compared with other materials such as nitrile rubber, the compression permanent deformation rate (<10%) of silica gel at a high temperature above 150 DEG C is significantly better than that (>30%) of nitrile rubber, and silica gel is suitable for long-term high-temperature test scenes. Compared with polyurethane, the friction coefficient of silica gel decays at a rate (<5% / year) lower than that (10% / year) of polyurethane after long-term use, thereby reducing the risk of fixation failure caused by material aging.

[0015] In terms of thickness, the elastic modulus of silica gel is about 2-5 MPa, and a 8mm-thick pad can absorb more than 90% of vibration energy with an amplitude of 0.5mm. In a conventional vibration test (amplitude ≤0.5mm), the occupied space is small, and it is suitable for compact test tables. The thickness of 12mm can cope with extreme test conditions with an amplitude of 0.8-1mm, and it is suitable for high-vibration amplitude or high-battery gravity conditions.

[0016] Preferably, the push rod is an electric push rod, and the electric push rod can automatically control the position of the protection pad through PLC.

[0017] Further, the device further comprises a controller, and the controller is used for controlling vibration test and collecting test data.

[0018] The device has the advantages and beneficial effects that the wide-frequency vibration of the linear vibration motor and the vibration sensor are cooperatively designed, the battery feedback signal can be collected in real time in the vibration process, the limitation that the traditional offline detection method cannot capture dynamic structure changes is broken, real-time diagnosis of problems such as looseness and fracture in the lithium battery is realized, and the timeliness of detection is significantly improved. The test table, the vibration source, the sensor and the protection structure are highly integrated, and are suitable for laboratory and production line rapid deployment. Key components are designed in a modular manner, and are convenient to maintain and replace. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 The utility model discloses a schematic diagram.

[0020] Fig. 2 The utility model discloses a schematic diagram of the test part of the utility model.

[0021] Fig. 3 The utility model discloses a schematic diagram of the positioning part of the utility model.

[0022] Fig. 4 The utility model discloses a schematic diagram of the protection part of the utility model.

[0023] Wherein, 1-test part, 11-test table, 12-base, 13-strut, 14-cushion pad, 15-vibration motor, 16-vibration sensor, 2-positioning part, 21-vertical frame, 22-cross frame, 23-cylinder, 24-positioning rubber block, 3-protection part, 31-fixed frame, 32-push rod, 33-protection pad, 4-controller. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the utility model. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the utility model, and are not used to limit the utility model. In the utility model, the orientation words such as 'up' and 'down' are generally used to indicate the up and down of the device in the actual use or working state, and the specific direction is the direction of the drawing in the drawings. And 'inner' and 'outer' are used in relation to the outline of the device.

[0025] As shown in Figs. 1 to 4 A lithium battery internal structure integrity device based on vibration detection, the device mainly includes a test part 1, a positioning part 2 and a protection part 3.

[0026] In this embodiment, the test table 11 is a rectangular flat plate, and the bottom surface is fixedly connected to the base 12 by bolts. Four support columns 13 are vertically welded at the corners of the periphery of the base 12, and the top ends of the support columns 13 are embedded in natural rubber shock pads 14 with a thickness of 10 mm. The test table 11 is supported above the support columns 13 by the shock pads 14. A linear vibration motor 15 is fixedly connected to the center of the bottom surface of the test table 11 by a countersunk screw. The vibration direction of the motor is perpendicular to the surface of the test table 11. A circular hole with a diameter of 8 mm is formed in the middle of the test table 11. A vibration sensor 16 is fixedly connected in the hole by adhesive. The sensing end of the vibration sensor 16 is flush with the upper surface of the test table 11. The test part 1 is connected to the controller 4. The test table 11 and the base 12 are flexibly connected by the shock pads 14, and the vibration motor 15 and the test table 11 are rigidly connected.

[0027] Two vertical frames 21 are vertically welded on the edges of the test table 11, and the top parts are welded to form a door frame structure by the cross frame 22. A cylinder 23 is installed on the upper middle part of the cross frame 22. The piston rod of the cylinder 23 passes through the through hole in the middle part of the cross frame 22 and is connected to the positioning rubber block 24 by a flange plate and bolts. The bottom surface of the positioning rubber block 24 is provided with a sawtooth anti-slip pattern. The positioning rubber block 24 is movably connected to the cross frame 22 by the cylinder 23.

[0028] The fixed frame 31 is symmetrically installed on the two side edges of the test table 11 by bolts. Three electric push rods 32 are arranged on the horizontal section of each fixed frame 31. The axis of the electric push rod 32 is parallel to the length direction of the test table 11. The front end of the electric push rod 32 is connected to a silica gel protective pad 33 with a thickness of 8 mm. The protective pad 33 is adjustably connected to the fixed frame 31 by the electric push rod 32.

[0029] Usage:

[0030] Parameter setting: The battery model, test frequency range (50-500 Hz) and amplitude parameters are input through the controller 4. The system automatically calculates the target distance of the electric push rod 32 and drives it to move, so that the distance between the two protective pads 33 is adapted to the width of the battery (error ≤ ±1 mm).

[0031] Battery fixation: Place the lithium battery in the center of the test table 11. Start the cylinder 23 to push the positioning rubber block 24 to press down. The pressure sensor controls the positioning pressure to be 0.1-0.3 MPa to ensure that the top surface of the battery is in full contact with the positioning rubber block 24.

[0032] Vibration test: The linear vibration motor 15 vibrates at a preset frequency. The vibration sensor 16 collects the acceleration signal of the test table 11 in real time and transmits it to the signal analysis system. The protective pad 33 absorbs vibration energy by elastic deformation of silica gel. The wavy groove can enhance the lateral restraint force to prevent the battery from sliding sideways.

[0033] Test end: The cylinder 23 retracts to release the battery, and the electric push rod 32 returns to the initial position. The system feeds back the test results to the controller 4.

[0034] The above has carried out the detailed introduction to the device for detecting the internal structure integrity of lithium battery based on vibration. The principle and implementation mode of the present application are described by applying specific examples. It should be pointed out that, for ordinary skilled in the art, without departing from the principle of the present application, the present application can be improved and modified, and these improvements and modifications also fall within the protection scope of the present application.

Claims

1. A device for detecting the internal structural integrity of a lithium battery based on vibration detection, comprising a testing unit (1), characterized in that, The testing unit (1) includes a testing platform (11), which is a rectangular plate. A base (12) is provided at the bottom of the testing platform (11). Support columns (13) are provided at the four corners of the base (12). A shock-absorbing pad (14) is provided above the support columns (13). The testing platform (11) is located above the shock-absorbing pad (14). A vibration motor (15) is provided below the testing platform (11). A circular hole is opened in the middle of the testing platform (11), and a vibration sensor (16) is provided in the circular hole.

2. The device for detecting the internal structural integrity of a lithium battery based on vibration detection according to claim 1, characterized in that, The vibration motor (15) is a linear vibration motor with a vibration frequency of 50-500Hz.

3. The device for detecting the internal structural integrity of a lithium battery based on vibration detection according to claim 2, characterized in that, The shock-absorbing pad (14) is made of natural rubber with a thickness of 8-15mm.

4. The device for detecting the internal structural integrity of a lithium battery based on vibration detection according to claim 3, characterized in that, The device also includes a positioning part (2), which includes two vertical frames (21) on the left and right, and a horizontal frame (22) is provided between the vertical frames (21). The vertical frames (21) and the horizontal frame (22) form a door frame-like support and are set on the test bench (11). A cylinder (23) is provided in the upper middle part of the horizontal frame (22). The working part of the cylinder (23) passes through the horizontal frame (22), and a positioning rubber block (24) is provided at the lower working part of the cylinder (23).

5. A device for detecting the internal structural integrity of a lithium battery based on vibration detection according to claim 3, characterized in that, The device also includes a protective part (3), which is disposed on the left and right sides of the test bench (11). The protective part (3) includes a fixing frame (31), which is disposed on both sides of the test bench (11). Multiple push rods (32) are disposed inward on the side of the fixing frame (31), and a protective pad (33) is disposed at the front end of the push rod (32).

6. The device for detecting the internal structural integrity of a lithium battery based on vibration detection according to claim 5, characterized in that, The protective pad (33) is made of 8-12mm silicone material.

7. A device for detecting the internal structural integrity of a lithium battery based on vibration detection according to claim 6, characterized in that, The push rod (32) is an electric push rod.

8. A device for detecting the internal structural integrity of a lithium battery based on vibration detection according to any one of claims 1 to 7, characterized in that, The device also includes a controller (4) for controlling the vibration test and collecting test data.

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