CN-121995250-A - Electrical core mechanical safety coupling evaluation method and test device

CN121995250ACN 121995250 ACN121995250 ACN 121995250ACN-121995250-A

Abstract

The invention discloses an evaluation method and a test device for mechanical safety coupling of an electric core. The method comprises the steps of performing impact tests on the battery cells by using an impact body under different test conditions, wherein the impact body is provided with a structure for simultaneously generating an extrusion effect and a needling effect during impact, acquiring voltage data, temperature data and appearance states of the battery cells and impact speed of the impact body in each impact test, calculating impact energy based on the mass and impact speed of the impact body, evaluating safety performance of the battery cells based on the voltage data, the temperature data, the appearance states and the impact energy under different test conditions, and respectively quantifying severity of extrusion and needling effects in the impact body through an extrusion evaluation model and a needling evaluation model so as to analyze dominant modes in mechanical damage. The invention can realize synchronous simulation, quantitative evaluation and analysis of the influence of extrusion and needling coupling damage on the safety of the battery cell, and remarkably improves the authenticity of the test and the comprehensiveness of the evaluation.

Inventors

Su can
YANG HUIMIN
AN HONGLI
Du Runkun
SONG CI
WANG LIPENG
ZHENG XUHAN

Assignees

北京新能源汽车股份有限公司
北京新能源汽车股份有限公司蓝谷动力系统分公司

Dates

Publication Date: 20260508
Application Date: 20260206

Claims (10)

1. A method for evaluating mechanical safety coupling of an electrical cell, comprising: Under different test conditions, the electric core is subjected to impact test by utilizing an impact body, wherein the impact body is provided with a structure for simultaneously generating an extrusion effect and a needling effect during impact; acquiring voltage data, temperature data and appearance state of the battery cell and the impact speed of the impact body in each impact test; Calculating impact energy based on the mass and impact velocity of the impact body; evaluating the safety performance of the battery cell based on the voltage data, the temperature data, the appearance state and the impact energy under different test conditions; and quantifying the severity of the extrusion and needling actions in the impact body by an extrusion evaluation model and a needling evaluation model respectively to analyze the dominant mode in the mechanical damage.
2. The method for evaluating mechanical safety coupling of a cell according to claim 1, characterized in that the test conditions include: Different states of charge of the cells, and different impact energies obtained by adjusting the release height, release angle or mass of the impact body.
3. The method of claim 1, wherein the impact testing is accomplished by driving the impact body in the form of a free fall or pendulum.
4. The method of claim 1, wherein the extrusion evaluation model is used to calculate an extrusion evaluation factor that characterizes the severity of extrusion, and the expression is: ; Wherein, the The total amount of work displacement is done for the impact body vertical to the surface of the battery cell, As a function of the dimensions and mechanical properties of the cells, For the upper limit of the working displacement, In order to test the quality of the impact body, For the quality of the electrical core to be measured, Is the falling height or equivalent falling height of the impact body.
5. The method of claim 4, wherein the needling evaluation model is used to calculate a needling evaluation factor that characterizes the severity of needling, expressed as: ; Wherein, the To the depth of penetration of the protruding structures into the cell to be tested, For a standard penetration depth for a conventional needling test, Is a half cone angle of the convex structure.
6. The method of claim 5, wherein analyzing dominant modes of mechanical damage comprises: Comparison And (3) with Is a numerical value of (2); If it is Judging that the needling factor is the dominant mode of mechanical damage; If it is The crush factor is determined to be the dominant mode of mechanical damage.
7. The method of claim 1, wherein the impact body comprises a body and at least one protrusion disposed on a surface of the body.
8. The method of evaluating mechanical safety coupling of a cell according to claim 7, wherein the protruding structure is a tapered structure detachably mounted on the main body, which is made of tungsten steel or stainless steel, has a height of 5mm to 60mm, a tip diameter of 1mm to 20mm, a tail diameter of 1mm to 50mm, and a half taper angle of 15 ° to 45 °.
9. The method of claim 1, wherein the computational expression of the impact energy is: E ; Wherein, the For the mass of the impact body, For the striking speed of the impact body, , The acceleration of the gravity is that, Is the falling height or equivalent falling height of the impact body.
10. A cell mechanical safety coupling test device for implementing the cell mechanical safety coupling evaluation method according to any one of claims 1 to 9, the device comprising: The fixing tool is used for fixing the battery cell; an impact body provided with a structure for simultaneously generating extrusion and needling effects upon impact; a release mechanism for releasing the impact body to strike the cell in a free-falling or pendulum manner; The control module is used for controlling the release mechanism to release the impact body; the data acquisition unit is used for acquiring voltage data, temperature data and appearance state of the battery cell and the impact speed of the impact body; The analysis processing unit is in communication connection with the data acquisition unit and is used for calculating impact energy based on the speed data, evaluating the safety performance of the battery cell based on the voltage data, the temperature data, the appearance state and the impact energy under different test conditions, and respectively quantifying the severity of the extrusion action and the needling action in the impact body through the extrusion evaluation model and the needling evaluation model so as to analyze the dominant mode in the mechanical damage.

Description

Electrical core mechanical safety coupling evaluation method and test device Technical Field The invention belongs to the technical field of electrical core safety test, and particularly relates to an electrical core mechanical safety coupling evaluation method and a test device. Background The electric core is used as a core energy storage unit of the lithium ion power battery, and the mechanical safety of the electric core is a key factor affecting the overall safety and reliability of application scenes such as electric automobiles, energy storage systems and the like. In the actual use process, the battery cell can bear complex mechanical load due to unexpected events such as vehicle collision, battery pack falling, foreign matter collision and the like, so that the internal structure of the battery cell is damaged, and serious safety accidents such as internal short circuit, thermal runaway, fire explosion and the like can be caused. Therefore, a scientific and effective mechanical safety evaluation method is established, and the method has important significance for design optimization, quality control and safety standard formulation of the battery cell product. At present, standardized test methods for the mechanical safety of an electric core in the industry mainly focus on two types of single mechanical abuse scene simulation, namely extrusion test and needling test. Extrusion testing generally simulates static or quasi-static mechanical loads. The test observes its physical deformation, whether an internal short circuit occurs, and whether thermal runaway is triggered by slowly applying a compressive force to the cell. However, this method has a low loading rate and a long process duration, and is unable to accurately reproduce the instantaneous, high energy impact events common in real collision accidents. The test result mainly reflects the safety of the battery cell under slow deformation, but is difficult to effectively capture key mechanisms such as dynamic response under impact load, impact heat caused by instantaneous energy injection and the like, and the test scene has obvious difference from a real high-momentum collision working condition. The needling test then simulates the extreme case of a sharp foreign object piercing the cell membrane. The test uses a metal steel needle to pierce the cell at a constant speed, artificially triggering an internal short circuit and observing thermal runaway behavior. Although this method is directly effective for triggering internal short circuits, its mechanical triggering mode is too single and special, representing only a sharp, localized puncture lesion. In actual complex accidents (such as vehicle side impact or bottom scraping), the cells are more commonly subjected to large area crush, wrinkling, tearing and their attendant localized penetration, etc. coupled damage patterns caused by blunt or structural members. A single sharp needle stick cannot characterize this more common complex failure mode caused by blunt impact. In summary, the conventional standardized testing methods (extrusion and needling) take into account both the extrusion and penetration modes of mechanical damage in isolation. However, under real mechanical abuse conditions, the cell damage is often the result of multiple modes acting together, coupled to each other. This coupling effect can significantly change the failure threshold, thermal trigger sensitivity, and hazard level of the power core. The current separated test system is difficult to simulate and evaluate the coupling damage effect, so that the safety risk of the battery cell under the actual complex working condition is not revealed enough, and a comprehensive and accurate input basis cannot be provided for the mechanical safety design of the battery cell. Therefore, a new method and a corresponding device for simulating and quantitatively evaluating the safety performance of the battery cell under the coupling action of extrusion and needling are needed in the industry, so as to fill the blank of the existing test system in simulating the actual and complex mechanical abuse scene, and improve the engineering relevance of the test result and the accuracy of safety early warning. Disclosure of Invention The invention aims to provide an electric core mechanical safety coupling evaluation method and a test device, which solve the key technical problems that the traditional electric core mechanical safety test method is used for carrying out extrusion and needling damage in isolation and can not simulate the coupling action of the extrusion and needling damage in real complex working conditions, realize synchronous simulation, quantitative evaluation and analysis of the influence of the extrusion and needling coupling damage on the electric core safety, and remarkably improve the authenticity and the comprehensiveness of the test. To achieve the above object, in a first aspect, the present invention provides a meth