Device for real-time non-contact measurement of pressure distribution and thickness distribution of lithium battery

Abstract

The utility model belongs to the technical field of lithium battery testing, and particularly relates to a device for measuring pressure distribution and thickness distribution of a lithium battery in a real-time non-contact manner, which comprises an expansion force and force distribution testing mechanism, the mechanism is of a left-right structure, and the battery is vertically placed in a module; the device for measuring the pressure distribution and the thickness distribution of the lithium battery in the real-time non-contact manner further comprises a battery thickness measuring mechanism, and the expansion force and force distribution measuring mechanism comprises a first mounting plate, a second mounting plate, a pressure mapping sensor, a guide shaft and an annular force sensor. The utility model has the advantages that the expansion force and the force distribution condition of the battery can be accurately measured in real time; the thickness distribution condition of the battery is accurately measured in real time; according to the results, analysis and research of lithium battery expansive force behaviors, design of expansive force models, and providing of data support for module design and the like play an important role.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium battery testing, and in particular relates to a device for real-time contactless measurement of pressure distribution and thickness distribution of lithium batteries. Background Art

[0002] As sales of electric vehicles continue to grow, lithium-ion batteries are becoming more and more popular. Lithium batteries themselves pose safety risks, especially when they are improperly used or even abused, posing different hazards such as electrical, chemical and thermal hazards. In order to ensure high safety standards, the mechanical behavior of the battery throughout its service life must be investigated, especially the expansion force.

[0003] The pressure distribution of the expansion force is one of the key mechanical parameters that affects not only the electrical performance of the battery but also the safety performance of the battery. The impact of the pressure distribution of the expansion force is more pronounced in the next-generation lithium metal batteries, which experience larger volume changes than conventional lithium metal batteries. Uneven pressure distribution may lead to local pore closure, which promotes the occurrence of higher local current density, resulting in hot spots and local overcharging, leading to local lithium plating. Hot spots and lithium plating accelerate uneven aging or even severe degradation, and increase the risk of internal short circuits and may eventually lead to thermal runaway.

[0004] At present, the literature mainly focuses on the overall measurement of battery thickness or force evolution during electrochemical cycles, while local changes are only sporadic. In-depth understanding of the reversible expansion caused by aging and the pressure distribution of the expansion force. According to experience, the distribution of the expansion force is consistent with the distribution of battery thickness. Therefore, measuring the pressure distribution of the expansion force and the battery thickness distribution provides data support for studying the expansion behavior of the battery and model design. In order to obtain more accurate pressure distribution and thickness distribution, online non-contact measurement devices and measurement methods are required. Utility Model Content

[0005] Therefore, the purpose of this utility model is to accurately measure the expansion behavior and pressure distribution of the expansion force of lithium batteries during cycling or storage from a testing perspective, which is crucial for us to provide data support for studying its expansion behavior and model design. This utility model provides a device and a method for non-contact measurement of the distribution of lithium battery thickness.

[0006] To achieve the above-mentioned purpose, the utility model adopts the following technical solutions: a device for real-time contactless measurement of pressure distribution and thickness distribution of lithium batteries, including a testing mechanism for expansion force and force distribution, which is a left-right structure, and the battery is placed upright in the module; the device for real-time contactless measurement of pressure distribution and thickness distribution of lithium batteries also includes: a battery thickness measuring mechanism.

[0007] Furthermore, the expansion force and force distribution testing mechanism includes a first mounting plate, a second mounting plate, a pressure mapping sensor, a guide shaft and an annular force sensor. The first mounting plate and the second mounting plate are arranged in parallel and are made of stainless steel. The pressure mapping sensor is arranged on the second mounting plate and is used to measure the pressure distribution on the battery surface. The guide shaft passes through the first mounting plate and the second mounting plate, and can fix and adjust the first mounting plate and the second mounting plate. The annular force sensor is mounted on the guide shaft and is mainly used to set the initial preload force and measure the force.

[0008] Furthermore, a battery can be placed between the first mounting plate and the second mounting plate, the surfaces of the first mounting plate and the second mounting plate close to each other are insulated, the pressure mapping sensor is arranged on the surface of the second mounting plate close to the battery, and the second mounting plate can slide along the guide shaft under pressure.

[0009] Furthermore, a spring is sleeved on the guide shaft, and the spring is mainly used for elastic support. In actual testing, different types of springs can be selected for use according to the type of expansion force test.

[0010] Furthermore, the battery thickness measuring mechanism includes two displacement sensors, which can actually measure the distance between the first mounting plate and the second mounting plate. In order to ensure seamless adhesion and zero point selection error during the test, the two displacement sensors are respectively arranged on the first mounting plate and the second mounting plate, and the two displacement sensors can be freely extended and retracted through magnetic induction.

[0011] Compared with the existing technology, the advantages of the utility model are: accurate and real-time measurement of the expansion force and force distribution of the battery; accurate and real-time measurement of the thickness distribution of the battery; based on the above results, it is important to analyze and study the expansion force behavior of lithium batteries, design expansion force models, and provide data support for module design. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the top view of a device for real-time contactless measurement of pressure distribution and thickness distribution of a lithium battery provided by the utility model;

[0013] Figure 2 It is a schematic diagram of the arrangement and power collection of a device for real-time contactless measurement of pressure distribution and thickness distribution of lithium batteries provided by the utility model;

[0014] Figure 3 It is a schematic diagram of thickness measurement of a device for real-time contactless measurement of pressure distribution and thickness distribution of a lithium battery provided by the utility model;

[0015] Figure 4 It is the pressure distribution diagram under different preload conditions of 0% SOC and 100% SOC;

[0016] Figure 5 This is the thickness distribution diagram under different preload conditions of 0% SOC and 100% SOC.

[0017] In the figure, 1 is a spring, 2 is an annular force sensor, 3 is a first mounting plate, 4 is a pressure mapping sensor, 5 is an experimental battery, 6 is a second mounting plate, 7 is a displacement sensor, and 8 is a guide shaft. DETAILED DESCRIPTION

[0018] The following embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0019] Example

[0020] This embodiment mainly describes the test mechanism and test principle of expansion force and force distribution: it mainly includes a first mounting plate 3 and a second mounting plate 6 which are parallel to each other, and are generally made of stainless steel. The experimental battery 5 is installed between the first mounting plate 3 and the second mounting plate 6, but the contact surfaces of the first mounting plate 3, the second mounting plate 6 and the experimental battery 5 need to be insulated to prevent the installation of the experimental battery 5 or the whole test process from being conductive, and the insulation treatment should be tight; there is a pressure mapping sensor 4 of the same size on the contact surface of the second mounting plate 6 and the experimental battery 5, and the collected force data is synchronously synthesized into a pressure distribution map for measuring The pressure distribution on the surface of the experimental battery 5; the guide shaft 8 runs through the first mounting plate 3 and the second mounting plate 6 to fix and adjust the first mounting plate 3 and the second mounting plate 6; the second mounting plate 6 moves left and right along the guide shaft 8 under the action of pressure, and an annular force sensor 2 is sleeved on the guide shaft, which is mainly used to set the initial preload and force measurement; in addition, a spring 1 is sleeved on the guide shaft 8, and different springs 1 are selected according to the expansion force test type, and the spring 1 mainly provides elastic support; the test mechanism for expansion force and force distribution is a left-right structure, and the battery is generally placed upright in the module, so it is also placed upright during the test. The experimental battery 5 expands with the cycle of charge and discharge, and the annular force sensor 2 senses it, triggering the pressure mapping sensor 5, and synchronously measuring the force distribution on the surface of the experimental battery 5 in time. There are two groups of experiments, each group of experiments has 2 parallel sample experimental batteries 5, and the two groups of experiments use different initial preloads, (a) (b) is one group, and cd is another group. The results are as follows Figure 4 shown.

[0021] This embodiment mainly illustrates the testing principle of the battery thickness measuring mechanism, which mainly includes: a guide rail 1 and a displacement sensor 7. The displacement sensor 7 is retractable and capacitive, and can realize the free movement of the displacement sensor 7 installed on the surface of the experimental battery 5.

[0022] Here’s how it works:

[0023] First, follow Figure 2 As shown, the two large surfaces of the experimental battery 5 are assumed to be divided into several small grids, mainly to facilitate the subsequent acquisition procedure of setting the position of the displacement sensor 7; the displacement sensor 7 is controlled and the program is edited and sent by a computer, and the position is generally acquired in the order from left to right and from top to bottom; then, according to Figure 3 As shown, the distance between the two planes of the first mounting plate 3 and the second mounting plate 6 that are in contact with the experimental battery 5 is represented by R, which is also the probe spacing of the capacitive displacement sensor 7; in the absence of contact, the distance d1 from the first mounting plate 3 to the surface of the experimental battery 5 and the distance d2 from the second mounting plate 6 to the surface of the experimental battery 5 are measured; the symmetrical dual-probe design of the two capacitive displacement sensors 7 is mainly to avoid errors caused by the selection of the zero point; finally, the thickness of the experimental battery 5 is calculated according to the formula D=R-d1-d2. There are two groups of experiments, each with 2 parallel sample experimental batteries 5. The two groups of experiments use different initial preloads, (a) (b) for one group, and cd for the other group. The results are shown in Figure 5 shown.

[0024] Through Examples 1 and 2 of the present invention, the pressure distribution and thickness distribution of the battery during the cycle process can be obtained, providing data support for exploring the expansion force behavior of the battery under constant displacement.

[0025] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for real-time non-contact measurement of pressure distribution and thickness distribution of lithium batteries, comprising: The expansion force and force distribution test mechanism is a left-right structure, and the battery is placed vertically in the module; Features: The device for real-time contactless measurement of pressure distribution and thickness distribution of lithium batteries also includes: Battery thickness measurement mechanism.

2. The device for real-time contactless measurement of pressure distribution and thickness distribution of lithium batteries according to claim 1, characterized in that: The expansion force and force distribution testing mechanism comprises a first mounting plate (3), a second mounting plate (6), a pressure mapping sensor (4), a guide shaft (8) and an annular force sensor (2); the first mounting plate (3) and the second mounting plate (6) are arranged in parallel; the pressure mapping sensor (4) is arranged on the second mounting plate (6) and is used to measure the pressure distribution on the battery surface; the guide shaft (8) passes through the first mounting plate (3) and the second mounting plate (6) and can fix and adjust the first mounting plate (3) and the second mounting plate (6); the annular force sensor (2) is sleeved on the guide shaft (8) and is used to set the initial preload force and measure the force.

3. The device for real-time contactless measurement of pressure distribution and thickness distribution of lithium batteries according to claim 2, characterized in that: A battery is arranged between the first mounting plate (3) and the second mounting plate (6); the first mounting plate (3) and the second mounting plate (6) are both insulated on a side close to each other; the pressure mapping sensor (4) is arranged on a side of the second mounting plate (6) close to the battery; and the second mounting plate (6) can slide along the guide shaft (8) under the action of pressure.

4. The device for real-time contactless measurement of pressure distribution and thickness distribution of lithium batteries according to claim 2, characterized in that: The guide shaft (8) is sleeved with a spring (1), and the spring (1) is used for elastic support.

5. The device for real-time non-contact measurement of pressure distribution and thickness distribution of lithium batteries according to claim 2, characterized in that: The battery thickness measuring mechanism comprises two displacement sensors (7), and the displacement sensors (7) are used to actually measure the distance between the first mounting plate (3) and the second mounting plate (6).

6. The device for real-time non-contact measurement of pressure distribution and thickness distribution of lithium batteries according to claim 5, characterized in that: The two displacement sensors (7) are respectively arranged on the first mounting plate (3) and the second mounting plate (6), and the two displacement sensors (7) can freely extend and retract through magnetic induction.

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