External pressurizing device for lithium battery expansibility evaluation

Abstract

The utility model discloses a special external pressure device for lithium battery expansibility assessment, which comprises a first fixing mechanism, a second fixing mechanism, nuts, bolts, springs, a pressure sensor and a battery clamp, the two fixing mechanisms are connected and fastened by four groups of bolts and nuts, the top of each bolt is sleeved with the spring, and the pressure sensor is connected with the battery clamp. The spring is used for applying pressure to the two fixing mechanisms; a pressure sensor and a battery clamp are arranged between the two fixing mechanisms; the pressure sensor is placed between the first fixing mechanism and the battery clamp and is used for obtaining external pressure borne by the battery; the battery clamp consists of two semi-rigid material plates, namely a left semi-rigid material plate and a right semi-rigid material plate, and can be used for clamping a soft package battery and a cylindrical battery. The device can pressurize the outer surfaces of the soft package battery and the cylindrical battery, and monitor the external load and the temperature condition of the battery.

Description

Technical Field

[0001] This utility model belongs to the technical field of battery quality control and safety, specifically relating to an external pressure device for evaluating the expansion force of lithium batteries. Background Technology

[0002] The electrification of automobiles is driving the rapid development of the lithium-ion battery materials industry. As a core component of new energy vehicles, the demand for power batteries is surging. Lithium-ion power batteries, with their higher energy density and performance, are currently the mainstream batteries used in new energy intelligent vehicles. Lithium-ion batteries possess advantages such as high operating voltage, wide operating range, stable discharge, and high specific power, and are widely used in electric vehicles, 3C digital products, and energy storage devices. As the requirements for lithium-ion battery end products continue to increase, the various performance aspects of lithium-ion batteries also need continuous improvement, such as structural stability, safety performance, and surface hardness.

[0003] The mechanical properties of lithium-ion batteries include elastic modulus, tensile strength, and thickness, which collectively determine the battery's structural stability and performance. With increasing electrode thickness, SEI film growth, and gas generation, the cell expands, directly impacting battery safety. Improving cell stiffness not only enhances aesthetics but also improves safety performance, such as resistance to impacts from hard objects, drops from heights, and compression. It also plays a crucial role in the safety design of the battery module. Battery pressurization devices apply appropriate external loads to lithium batteries, allowing for testing the impact of different external loads on battery performance and monitoring external temperature changes to ensure performance meets factory requirements—an essential step. Therefore, simple and practical pressurization devices and testing methods for evaluating the mechanical properties of lithium-ion batteries are not only significant for the battery testing industry but also crucial for ensuring the safety and stability of lithium batteries. In practical applications, understanding and optimizing these mechanical properties helps improve the safety, reliability, and lifespan of lithium-ion batteries. Summary of the Invention

[0004] The main objective of this invention is to overcome the shortcomings and deficiencies of existing technologies and provide a dedicated external pressurization device for evaluating the expansion force of lithium batteries. This device can apply pressure to the outer surface of pouch batteries and cylindrical batteries, monitoring the magnitude of the external load and temperature conditions of the battery. Simultaneously, mechanical properties and temperature changes are related to the internal state of the lithium battery. By utilizing the battery's external load change data and temperature data obtained during the testing process, it is possible to predict the battery's SOC (State of Charge) and SOH (State of Health).

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, this utility model provides a special external pressure device for assessing the expansion force of lithium batteries. The device includes a first fixing mechanism, a second fixing mechanism, nuts, bolts, springs, pressure sensors, and battery clamps. The first fixing mechanism has a sensor mounting groove and a fixing through hole on its inner surface; the second fixing mechanism has a plate mounting groove and a through hole on its inner surface; the nuts, bolts, and springs are grouped together, and several groups are provided; several battery clamps are provided, each including a pair of semi-rigid material plates; the fixing through holes are evenly distributed along the inner surface edge of the first fixing mechanism, and the through holes are evenly distributed along the inner surface of the second fixing mechanism, with the number of through holes corresponding to the number of fixing through holes; the bolts have a resistance mechanism at their tops; and the springs have a radius larger than the fixing through holes and the through holes.

[0007] In use, the pressure sensor is mounted on the inner surface of the first fixing mechanism through the sensor mounting slot. The battery clamp aligns the battery and places it between the semi-rigid material plates. The outer surface of one semi-rigid material plate contacts the measuring end of the pressure sensor, and the other semi-rigid material plate is mounted on the inner surface of the second fixing mechanism through the plate mounting slot. The bottom of the bolt is connected to the nut through a fixing through hole and a through hole. The inner surface of the resistance mechanism contacts the outer surface of the first fixing mechanism. The spring is sleeved on the top of the bolt, and the top of the spring contacts the inner surface of the first fixing mechanism. When the nut is tightened, the first fixing mechanism and the second fixing mechanism clamp and fix the battery, the battery clamp, and the pressure sensor.

[0008] As a preferred technical solution, the first fixing mechanism and the second fixing mechanism are made of steel plate or other alloy plate.

[0009] As a preferred technical solution, the semi-rigid material plates are all made of aluminum alloy.

[0010] As a preferred technical solution, the inner surface of the semi-rigid material plate is provided with a groove for temperature measurement, and the groove for temperature measurement extends from the edge of the inner surface of the semi-rigid material plate to near the center line of the inner surface.

[0011] As a preferred technical solution, the groove for temperature measurement is a temperature measuring line groove, and at least one temperature measuring line groove is provided; when more than one temperature measuring line groove is provided, the position of the temperature measuring line groove is set according to the direction and position of the positive and negative terminals of the battery.

[0012] As a preferred technical solution, when testing a soft-pack battery, the groove used for temperature measurement is a "well" shaped groove or a "+" shaped groove, used to measure the temperature changes at the positive and negative electrodes and the edges of the soft-pack battery;

[0013] When testing a cylindrical battery, the groove for temperature measurement extends from the upper and lower edges of the inner surface of the semi-rigid material plate to near the center line, and is used to measure the temperature change at the cylindrical positive and negative electrodes.

[0014] As a preferred technical solution, the inner surface of the semi-rigid material plate is provided with a battery mounting groove, which is cut from the center of the inner surface outwards according to the battery type.

[0015] As a preferred technical solution, the battery mounting slot is a cube, cuboid, cylinder, polygonal prism, or other prism.

[0016] As a preferred technical solution, battery testing also includes power lines, thermocouples, multiplexers, RS-485 / 422 converters, and signal lines.

[0017] As a preferred technical solution, during battery testing, the positive and negative terminals of the battery are connected to the battery performance test bench via the power line and signal test line. The pressure sensor is connected to the multi-channel transmitter, which is connected to the computer interface via a USB to RS-485 / 422 converter. When the first and second fixing mechanisms clamp and fix the battery, battery clamp, and pressure sensor, the pressure applied by the springs to the first and second fixing mechanisms is slowly adjusted and kept parallel. The thermocouple is installed in the groove for temperature measurement and is connected to the computer interface via a signal line.

[0018] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0019] The battery clamp of this invention uses a semi-rigid material. These materials deform to a certain extent under stress, but do not undergo complete plastic deformation. Typical semi-rigid materials have a certain degree of elasticity, meaning they deform under stress but return to their initial or near-initial state after stress is removed. Therefore, this device can apply pressure to the deformation peaks of the battery while reducing pressure on the deformation troughs of the pouch battery's outer surface. Thanks to the spring, the device can apply pressure to the rigid plate and adjust the magnitude of the applied pressure, while ensuring uniform pressure distribution. Furthermore, the combination of the semi-rigid material plate and the spring ensures pressure stability even when the pouch battery's outer surface deforms. Finally, because the device is equipped with a pressure sensor, it can obtain the applied pressure signal, which can be directly converted into a numerical value by a transmitter and displayed on a computer, making it simple and convenient, and improving pressure monitoring and control capabilities. In summary, the pressurizing device of this invention has the function of applying appropriate pressure to batteries of different shapes and ensuring pressure stability, providing reliable assurance for battery production and safety performance.

[0020] In practical applications, changes in charge / discharge rates can alter the stress on the battery. Therefore, these factors must be considered when designing a battery structure with good mechanical stability. Understanding the mechanical properties of a battery under different conditions helps in assessing its safety performance. For thin-walled batteries such as pouch cells, the expansion force curve provides crucial information about the battery's expansion under different pressures and rates, thus enabling an assessment of battery safety. Based on the battery's mechanical properties under various conditions, corresponding usage specifications and safety standards can be developed to ensure the battery's safety and reliability in practical applications. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is an overall structural diagram of the external pressurization device for evaluating the expansion force of lithium batteries, according to an embodiment of this utility model.

[0023] Figure 2 These are schematic diagrams of different semi-rigid material plate clamping structures in embodiments of this utility model;

[0024] Figure 3 The graph shows the change in expansion force under an external pressure of 600 N in the embodiment of this utility model.

[0025] In the diagram: 1-First fixing mechanism; 2-Second fixing mechanism; 3-Nut; 4-Bolt; 5-Spring; 6-Pressure sensor; 7-Battery clamp; 8-Battery. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0027] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0028] First embodiment.

[0029] This embodiment provides a dedicated external pressure device for assessing the expansion force of lithium batteries, comprising a first fixing mechanism 1, a second fixing mechanism 2, a nut 3, a bolt 4, a spring 5, a pressure sensor 6, and a battery clamp 7. The inner surface of the first fixing mechanism 1 is provided with a sensor mounting groove and a fixing through hole. The inner surface of the second fixing mechanism 2 is provided with a plate mounting groove and a through hole. The nut 3, bolt 4, and spring 5 are grouped together, and several groups are provided. Several battery clamps 7 are provided, each battery clamp 7 including a pair of semi-rigid material plates. The fixing through holes are evenly distributed on the inner surface edge of the first fixing mechanism 1 and evenly distributed on the inner surface of the second fixing mechanism 2. The number of through holes corresponds to the number of fixing through holes. The bolt 4 is provided with a resistance mechanism at its top. The radius of the spring 5 is larger than the fixing through holes and the through holes.

[0030] In use, the pressure sensor 6 is mounted on the inner surface of the first fixing mechanism 1 through the sensor mounting slot. The battery clamp 7 aligns the battery 8 and places it between the semi-rigid material plates. The outer surface of one of the semi-rigid material plates is in contact with the measuring end of the pressure sensor 6, and the other semi-rigid material plate is mounted on the inner surface of the second fixing mechanism 2 through the plate mounting slot. The bottom of the bolt 4 is connected to the nut 3 through a fixing through hole and a through hole. The inner surface of the resistance mechanism is in contact with the outer surface of the first fixing mechanism 1. The spring 5 is sleeved on the top of the bolt 4, and the top of the spring 5 is in contact with the inner surface of the first fixing mechanism 1. When the nut 3 is tightened, the first fixing mechanism 1 and the second fixing mechanism 2 clamp and fix the battery 8, the battery clamp 7, and the pressure sensor 6.

[0031] To ensure uniform heat conduction and stress distribution of the fixed battery 8 during pressure testing, the first fixing mechanism 1 and the second fixing mechanism 2 in this embodiment are made of steel plates or other alloy plates. Other alloy plates may also be tungsten steel alloys, beryllium copper alloys, nickel-chromium alloys, molybdenum alloys, and other metal-based composite materials, which possess good thermal conductivity and rigidity.

[0032] In use, the two fixing mechanisms are placed vertically parallel to each other and are fixed by bolts 4 and nuts 3.

[0033] Specifically, in this embodiment, the size and number of through holes and fixed through holes match the bolts 4. The through holes and fixed through holes can be evenly distributed in four directions of the first fixing mechanism 1 and the second fixing mechanism 2, forming four sets of nuts 3, bolts 4, and springs 5. A spring 5 is fitted onto the top of each bolt 4, and this spring 5 applies pressure to the two rigid plates, namely the first fixing mechanism 1 and the second fixing mechanism 2. During the fixing process, the top of the bolt has a resistance mechanism that can contact the outer surface of the first fixing mechanism 1 and provide tightening resistance. Furthermore, to accommodate tests with batteries 8 of different sizes and numbers, the through holes and fixed through holes can also be adjusted accordingly.

[0034] Furthermore, the resistance mechanism can be a hemisphere, a cylinder, or a nut, etc., and the side length or diameter of the resistance mechanism is larger than that of the fixed through hole.

[0035] For each battery clamp 7, there is a pair of semi-rigid material plates. Semi-rigid materials are those with properties between rigid materials (completely inoperable) and flexible materials (completely malleable). These materials deform to some extent when subjected to force, but do not undergo complete plastic deformation. Typical semi-rigid materials have a degree of elasticity, meaning they deform under stress but return to their initial or near-initial state after the stress is removed. Therefore, this device can apply pressure to the deformation peaks of the battery 8 while reducing the pressure on the deformation troughs of the outer surface of the pouch battery 8.

[0036] Furthermore, in this embodiment, the battery clamp 7 is made of aluminum alloy.

[0037] Furthermore, such as Figure 2 As shown, the inner surface of the semi-rigid material plate is provided with a battery mounting groove. In actual use, the battery mounting groove or the semi-rigid material plate can be replaced with a shape that adapts to the different types of batteries 8 being clamped. Specifically, the battery mounting groove can be designed as a cube, cuboid, cylinder, polygonal prism, or other prism.

[0038] Furthermore, in order to test multiple or multiple specifications of batteries 8 simultaneously, the number and mounting slots of the semi-rigid material plate can be adjusted according to the size and quantity of the batteries 8.

[0039] In the battery 8 test, to obtain the expansion force change curve, this embodiment includes a pressure sensor 6 and a thermocouple to provide the mechanical properties and heat release of battery 8 under different conditions. The pressure sensor 6 is located inside the device and directly contacts the battery clamp 7, thereby acquiring real-time pressure changes within the device. The thermocouple monitors the surface temperature changes of battery 8, especially the temperature at the positive and negative electrodes. Therefore, this embodiment provides a groove for temperature measurement on the inner surface of the semi-rigid material plate, extending from the edge of the inner surface to near the centerline. Specifically, see again... Figure 2 The inner surface of the semi-rigid material plate is provided with a temperature measuring line groove, and at least one temperature measuring line groove is provided; when more than one temperature measuring line groove is provided, the position of the temperature measuring line groove needs to be set according to the direction and position of the positive and negative terminals of the battery 8.

[0040] When the test is applied to pouch cells, it can be configured with a "well" shaped groove or a "+" shaped groove to measure the temperature changes at the positive and negative electrodes and edges of the pouch cell. When the test is applied to cylindrical cells, grooves are opened at both the top and bottom ends inside the rigid material plate to measure the temperature changes at the positive and negative electrodes of the cylinder.

[0041] The thermocouple wires are placed at different depths within the groove according to different temperature measurement points to measure the temperature of the positive and negative terminals and edges of battery 8, and the temperature of battery 8 is fed back in real time via the thermocouples. The semi-rigid material plate has a suitable shape for different types of batteries being clamped and can be replaced.

[0042] Second embodiment.

[0043] Based on the first embodiment, this embodiment is actually for specific data testing of battery 8, so it also requires a computer and its port, power cord, thermocouple, multiplexer, RS-485 / 422 converter and signal line.

[0044] To achieve the testing objective, this embodiment will employ the following settings:

[0045] (1) Place the battery 8 between the left half rigid material plate and the right half rigid material plate, and connect the positive and negative terminals of the battery 8 to the battery 8 performance test bench through the power line and signal test line.

[0046] (2) Connect the pressure sensor 6 to the multi-channel transmitter. The multi-channel transmitter is connected to the computer interface via a USB to RS-485 / 422 converter.

[0047] (3) Install the multi-channel test recording system APP on the computer. After debugging, the external pressure of battery 8 can be displayed.

[0048] (4) Place two magnetic small level instruments horizontally on the outside of the two steel plates, then tighten the four sets of bolts 4 and nuts 3 simultaneously and slowly. Apply load to the two rigid plates through spring 5. According to the pressure change displayed on the multi-channel test recording system APP on the computer, slowly adjust the pressure of spring 5 on the two rigid plates and keep the two rigid plates parallel until the pressure displayed on the multi-channel test recording system APP is consistent with the expected load size. This is the pressure on the outer surface of battery 8.

[0049] By applying an external force to battery 8, this force can be adjusted as needed. The pressure sensor 6 has a range of 0-1000 N, allowing for quick and convenient adjustment of the expected external pressure. The expansion force and temperature data during the charging and discharging process of battery 8 are collected by the pressure sensor 6 and the thermocouple, respectively, and fed back through a multi-channel test recording system APP on a computer. The above features are not found in existing patents. Furthermore, by analyzing this data, conclusions can be drawn, such as that under an external pressure of 600 N, changing the charging rate results in a generally consistent trend in expansion force change.

[0050] Third embodiment.

[0051] This embodiment conducts a pressure test on the outer surface of the pouch battery and explores its expansion force change characteristics. The pressure device is placed in a constant temperature chamber at 25 degrees Celsius, and the remaining settings are the same as in the second embodiment, specifically including the following settings:

[0052] (1) Set the initial external pressure to 300 N, and slowly tighten the four nuts 3 to apply pressure to the two rigid plates through the spring 5 and keep the two rigid plates parallel through the outer magnetic level until the external pressure is displayed as 300 N on the computer.

[0053] (2) The charge / discharge rate of battery 8 is increased from 0.5C to 2C. Each time the rate is increased by 0.5C, data is recorded.

[0054] (3) Increase the external pressure of battery 8 from 300N to 400N and repeat setting (2).

[0055] (4) Increase the external pressure of battery 8 from 400N to 500N and repeat setting (2).

[0056] (5) Increase the external pressure of battery 8 from 500N to 600N and repeat setting (2).

[0057] (6) Plot the obtained data using Origin plotting software, see Figure 3 .

[0058] According to the pressure testing method using the pressure device on the outer surface of the soft-pack battery involved in this embodiment, the required pressure that can be directly applied to the outer surface of the soft-pack battery can be obtained by manually adjusting the tightness of the bolt 4 and nut 3 and changing the magnitude of the force applied by the spring 5. This device can accurately control the magnitude of the external pressure applied to the outer surface of the battery 8.

[0059] Depend on Figure 3 It can be seen that under ambient temperature of 25℃ and external pressure of 600 N, the battery expansion force remains relatively consistent from 0.5C to 2C charging rates up to 30% SoC. From 30% to 100% SoC, the expansion force remains relatively consistent from 1C to 2C charging rates, but the expansion force is slightly lower at 0.5C. Studying the mechanical characteristics of the battery under these different conditions can provide important references for battery design and optimization, and help evaluate its safety performance.

[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. An external pressurization device for evaluating the expansion force of lithium batteries, characterized in that, The device includes a first fixing mechanism, a second fixing mechanism, nuts, bolts, springs, a pressure sensor, and battery clamps. The inner surface of the first fixing mechanism has a sensor mounting groove and a fixing through hole, and the inner surface of the second fixing mechanism has a plate mounting groove and a through hole. The nuts, bolts, and springs are grouped together, and several groups are provided. Several battery clamps are provided, and each battery clamp includes a pair of semi-rigid material plates. The fixing through holes are evenly distributed on the inner surface edge of the first fixing mechanism, and the through holes are evenly distributed on the inner surface of the second fixing mechanism. The number of through holes corresponds to the number of fixing through holes. The bolts have a resistance mechanism at the top, and the spring radius is larger than the fixing through holes and the through holes. In use, the pressure sensor is mounted on the inner surface of the first fixing mechanism through the sensor mounting slot. The battery clamp aligns the battery and places it between the semi-rigid material plates. The outer surface of one semi-rigid material plate contacts the measuring end of the pressure sensor, and the other semi-rigid material plate is mounted on the inner surface of the second fixing mechanism through the plate mounting slot. The bottom of the bolt is connected to the nut through a fixing through hole and a through hole. The inner surface of the resistance mechanism contacts the outer surface of the first fixing mechanism. The spring is sleeved on the top of the bolt, and the top of the spring contacts the inner surface of the first fixing mechanism. When the nut is tightened, the first fixing mechanism and the second fixing mechanism clamp and fix the battery, the battery clamp, and the pressure sensor.

2. The external pressurization device for assessing the expansion force of lithium batteries according to claim 1, characterized in that, The first fixing mechanism and the second fixing mechanism are made of steel plate or other alloy plate.

3. The external pressurization device for assessing the expansion force of lithium batteries according to claim 1, characterized in that, All the semi-rigid material plates are made of aluminum alloy.

4. The external pressurization device for assessing the expansion force of lithium batteries according to claim 1, characterized in that, The inner surface of the semi-rigid material plate is provided with a groove for temperature measurement, which extends from the edge of the inner surface of the semi-rigid material plate to near the center line of the inner surface.

5. The external pressurization device for assessing the expansion force of lithium batteries according to claim 4, characterized in that, The groove used for temperature measurement is a temperature measuring line groove, and at least one temperature measuring line groove is provided; when more than one temperature measuring line groove is provided, the position of the temperature measuring line groove is set according to the direction and position of the positive and negative terminals of the battery.

6. The external pressurization device for assessing the expansion force of lithium batteries according to claim 4, characterized in that, When testing a pouch battery, the groove used for temperature measurement is a "well" shaped groove or a "+" shaped groove, used to measure the temperature changes at the positive and negative electrodes and the edges of the pouch battery; When testing a cylindrical battery, the groove for temperature measurement extends from the upper and lower edges of the inner surface of the semi-rigid material plate to near the center line, and is used to measure the temperature change at the cylindrical positive and negative electrodes.

7. The external pressurization device for assessing the expansion force of lithium batteries according to claim 1, characterized in that, The inner surface of the semi-rigid material plate is provided with a battery mounting groove, which is cut from the center of the inner surface outwards according to the battery type.

8. The external pressurization device for assessing the expansion force of lithium batteries according to claim 7, characterized in that, The battery mounting slot is a cube, cuboid, cylinder, polygonal prism, or other prism.

9. The external pressurization device for assessing the expansion force of lithium batteries according to claim 1, characterized in that, Battery testing also includes power cords, thermocouples, multiplexers, RS-485 / 422 converters, and signal lines.

10. The external pressurization device for assessing the expansion force of lithium batteries according to claim 9, characterized in that, During battery testing, the positive and negative terminals of the battery are connected to the battery performance test bench via the power cord and signal test line. The pressure sensor is connected to the multi-channel transmitter, which is connected to the computer interface via a USB to RS-485 / 422 converter. When the first and second fixing mechanisms clamp and fix the battery, battery clamp, and pressure sensor, the pressure applied by the springs to the first and second fixing mechanisms is slowly adjusted and kept parallel. The thermocouple is installed in the groove for temperature measurement and is connected to the computer interface via a signal line.

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