CN116046239A - Method for testing internal pressure of lithium secondary battery module - Google Patents
Method for testing internal pressure of lithium secondary battery module Download PDFInfo
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- CN116046239A CN116046239A CN202310176163.4A CN202310176163A CN116046239A CN 116046239 A CN116046239 A CN 116046239A CN 202310176163 A CN202310176163 A CN 202310176163A CN 116046239 A CN116046239 A CN 116046239A
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- main battery
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/389—Measuring internal impedance, internal conductance or related variables
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention provides a method for testing internal pressure of a lithium secondary battery module, which relates to the technical field of lithium batteries, wherein a main battery core is adopted to assemble a thin film sensor with a common elastic material and a steel plate clamp, and then the main battery core is subjected to charge-discharge cycle test; s2: testing the contact pressure distribution state of the contact surface with the battery cell through a film sensor, and obtaining the cyclic expansion stress sigma of each area of the surface of the main battery cell from the expansion force distribution range of each area of the surface of the main battery cell, wherein the deformation of each area of the surface of the main battery cell is consistent in the charge-discharge cyclic process, namely the strain epsilon is consistent; s3: calculating a novel elastic material E, E=sigma/epsilon in the module according to the S2 test data; s4: each designed novel elastic material is assembled into an auxiliary battery cell to form a module, so that the problem of inconsistent deformation of each area caused by different expansion forces during charge and discharge cycles of the metal lithium battery module is solved.
Description
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a method for testing internal pressure of a lithium secondary battery module.
Background
The metal lithium battery adopts pure metal lithium as a cathode material, has ultrahigh theoretical specific capacity and extremely low potential, is expected to increase the endurance mileage of the electric automobile by more than one time, and is an important development direction of innovative breakthrough technology in the current battery industry. However, the use of metallic lithium as the negative electrode has the challenge of mutual containment, including lithium dendrite growth, instability of the solid electrolyte interface film, and accompanying huge volume change during charge and discharge, not only reducing battery efficiency, shortening service life, but also bringing potential safety hazards.
Compared with a lithium ion battery made of a common graphite negative electrode material, the lithium ion battery made of the common graphite negative electrode material has less lattice space for lithium ion intercalation graphite in the charging process, so that the charging expansion amount of the metal lithium battery is larger than that of the lithium ion battery made of the common graphite negative electrode material, and if the metal lithium battery is expanded, the negative electrode lithium sheet of the metal lithium battery is powdered in the charging and discharging processes, so that the attenuation of the metal lithium battery is accelerated. Therefore, when designing and manufacturing the metal lithium module, a certain initial pretightening force needs to be applied to the module, elastic foam can be added between the battery cores in the module, and the functions of isolation and heat insulation are achieved when the battery cores expand.
However, in the metal lithium battery cell cycle test, the expansion force of each area of the battery cell is inconsistent, when the battery cells are grouped, the expansion force of the battery cell positioned at the middle position of the module is larger, the battery cell close to the edge is smaller in expansion force, the inconsistent expansion amount of the surface of the metal lithium battery cell occurs, the deformation of the negative electrode metal lithium sheet is inconsistent, the negative electrode metal lithium sheet is seriously deformed, and various performances of the metal lithium battery cell are reduced.
Therefore, we propose a testing method for internal pressure of lithium secondary battery module, which uses the elastic material design method of the module to solve the problem of uneven expansion of the surface of the battery core during the charge-discharge cycle of the metal lithium module.
Disclosure of Invention
Aiming at the problems existing in the prior art, the method for testing the internal pressure of the lithium secondary battery module is provided.
The aim and the effect of the invention are achieved by the following specific technical means:
a method for testing internal pressure of a lithium secondary battery module comprises the following steps:
s1: the method comprises the steps of taking a main battery cell, assembling a thin film sensor with a common elastic material and a steel plate clamp, and then performing charge-discharge cyclic test on the main battery cell;
s2: testing the contact pressure distribution state of the contact surface with the battery cell through a film sensor, and obtaining the cyclic expansion stress sigma of each area of the surface of the main battery cell from the expansion force distribution range of each area of the surface of the main battery cell, wherein the deformation of each area of the surface of the main battery cell is consistent in the charge-discharge cyclic process, namely the strain epsilon is consistent;
s3: calculating a novel elastic material E, E=sigma/epsilon in the module according to the S2 test data;
s4: each designed novel elastic material is assembled into an auxiliary battery cell to form a module;
through the design, the elastic performance of each novel elastic material is inconsistent, and the novel elastic material corresponds to the expansion force of each battery cell in the battery cell circulation process.
Further preferred embodiments are as follows: in the S1, a thin film sensor is arranged on one side of a main battery cell, common elastic materials are arranged on the other side of the main battery cell and the outer side of the thin film sensor, and steel plate clamps are arranged outside the common elastic materials;
further: a fastening bolt is arranged between the steel plate clamps, the steel plate clamps are locked through the fastening bolt, the main battery core is tightly pressed by the common elastic material, and the film sensor can test the expansion pressure of the main battery core;
according to the design, the thin film sensor is clamped with the common elastic material and the main battery cell through the steel plate clamp, so that the expansion force of the main battery cell can be better tested.
Further preferred embodiments are as follows: in the step S4, the module includes:
the battery comprises a plurality of auxiliary battery cells which are arranged in parallel, novel elastic materials arranged between the auxiliary battery cells, a module aluminum plate clamp arranged outside the auxiliary battery cells, and a binding belt encircling the auxiliary battery cells, the novel elastic materials and the module aluminum plate clamp;
the elasticity of each piece of novel elastic material is designed according to the data measured by the film sensor.
Further preferred embodiments are as follows: a busbar is connected between the auxiliary battery cores;
and the multiple groups of auxiliary electric cores are connected through the bus bars.
Further preferred embodiments are as follows: the compressive resistance value of the novel elastic material is obtained by S3.
The invention has the beneficial effects that:
calculating the elastic coefficient required by the novel elastic material, wherein the novel elastic material E=sigma/epsilon is used as an elastic heat insulation material between the battery cells and the module end plate, so that when the module is in charge-discharge circulation, the expansion force of each region of the battery cells is different, but the expansion deformation of each region is consistent, thereby solving the problem of inconsistent deformation of each region caused by different expansion force when the metal lithium battery module is in charge-discharge circulation.
Drawings
The invention is further described with reference to the following description of the drawings.
Fig. 1 is a diagram of a cell structure (pressure test state) of the present invention;
fig. 2 is an assembled structure view of a battery module according to the present invention;
FIG. 3 is a pressure cloud chart of the main cell structure cycle process of the present invention;
fig. 4 is a pressure cloud of the main cell structure cycle process of the present invention.
In the figure: the novel electric power strip comprises a steel plate clamp (1), a common elastic material (2), a film sensor (3), a main electric core (4), a fastening bolt (5), a module aluminum plate clamp (6), a novel elastic material (7), an auxiliary electric core (8), a binding belt (9) and a busbar (10).
Detailed Description
In order that the above objects, features and advantages of the invention will be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. The following examples are merely illustrative of the practice of the invention. It should be noted that the disclosed embodiments do not limit the scope of the invention. On the contrary, the invention is intended to cover modifications and variations without departing from the scope of the invention.
Referring to fig. 1, a method for testing internal pressure of a lithium secondary battery module includes:
s1: the main battery cell 4 is taken, the thin film sensor 3, the common elastic material 2 and the steel plate clamp 1 are assembled, and then the main battery cell 4 is subjected to charge-discharge cycle test;
the method comprises the following steps: the method comprises the steps that a thin film sensor 3 is arranged on one side of a main battery cell 4, two pieces of common elastic materials 2 are picked up and placed on the outer side of the thin film sensor 3 and the other side of the main battery cell 4, then steel plate clamps 1 are respectively placed outside the common elastic materials 2, fastening bolts 5 are arranged between the steel plate clamps 1, the steel plate clamps 1 are locked through the fastening bolts 5, the common elastic materials 2 compress the main battery cell 4, the main battery cell 4 can perform charge and discharge circulation, the contact pressure distribution state of the contact surface with the main battery cell 4 is tested through the thin film sensor 3, the expansion force distribution range of each area on the surface of the main battery cell 4 is obtained, the cyclic expansion stress sigma of each area on the surface of the main battery cell 4 is obtained, the deformation of each area on the surface of the main battery cell 4 is consistent in the charge and discharge circulation process, namely the strain epsilon is consistent, the elastic coefficient required by a novel elastic material 7 is calculated, and the novel elastic material 7E=sigma/epsilon;
referring to fig. 2, after the elastic coefficient of each new elastic material 7 is designed according to the above manner, a plurality of new elastic materials 7 are obtained, and each new elastic material 7 is assembled into the secondary battery core 8 to form a module, which specifically comprises the following steps:
the auxiliary battery cores 8 are arranged in parallel, a space is reserved between the auxiliary battery cores 8, the novel elastic material 7 is placed in the corresponding space, the module aluminum plate clamp 6 is arranged outside the auxiliary battery cores 8, the two module aluminum plate clamps 6 are respectively located at the outermost sides of the modules, then the binding tape 9 is wound, the auxiliary battery cores 8, the novel elastic material 7 and the module aluminum plate clamp 6 are fastened through the binding tape 9, and the modules are formed to complete the work.
In the improved module, the auxiliary battery cells 8 are used as elastic heat insulation materials between the auxiliary battery cells 8 by using the novel elastic materials 7 in the charge-discharge cycle process, and the expansion deformation of each area of the auxiliary battery cells 8 is consistent although the cyclic expansion forces of each area are different in the charge-discharge cycle, so that the problem of inconsistent deformation of each area caused by the different expansion forces in the charge-discharge cycle of the module is solved.
Embodiment one:
in order to better simulate the state of a metal lithium battery core in a module and pack, a traditional battery core is tested by carrying a clamp when being subjected to a charge-discharge cycle test, as shown in fig. 1, common elastic materials 2 are respectively added at two ends of a main battery core 4, a thin film sensor 3 is added between the common elastic materials 2 and the main battery core 4 for measuring the expansion force and the change condition of the main battery core 4 during the cycle, the thickness of the thin film sensor 3 is 0.33mm, and the thin film sensor is ultrathin, flexible and bendable, can accurately measure the contact pressure distribution state of a contact surface, can display the contact pressure of the contact surface through a two-dimensional or three-dimensional pressure cloud picture, and can record the stress process of the whole charge-discharge cycle; then clamping the main battery cell 4, the film sensor 3 and the common elastic material 2 by using the steel plate clamp 1, and fixing and clamping by using the fastening bolt 5, wherein the initial pretightening force is 1Mpa;
as shown in fig. 1 and 3, after the steel plate clamp 1 is installed and an initial pretightening force of 1Mpa is applied, charging and discharging cycles are carried out on the main battery cell 4 at 25 ℃, the cyclic charging multiplying power is 0.2C, the discharging multiplying power is 1C, the contact pressure distribution in the whole process of charging and discharging cycles is monitored, and a pressure distribution cloud chart is shown in fig. 3;
wherein fig. 3 is a pressure cloud chart under an initial pretightening force of 1Mpa, it can be seen that under the pretightening force of 1Mpa, the pressure cloud chart in the middle of the main cell 4 is dark, the darker the color is, the larger the contact pressure is, and the pressure cloud chart in the position of the cell near the edge is light, the contact pressure is relatively smaller; after 10 cycles, the pressure cloud chart of the main battery cell 4 is shown in fig. 4;
in fig. 4, the pressure cloud image in the middle of the main cell 4 is black, which represents that the received contact pressure is larger, the actual test data is about 6-6.5Mpa, the pressure cloud image of the main cell 4 near the edge is light, which represents that the received contact pressure is smaller, the actual test data is about 4-5Mpa, and in the charge-discharge cycle process of the main cell 4, the expansion force of the main cell 4 is inconsistent, the expansion force is larger and the expansion force is closer to the edge of the main cell 4, the expansion force is smaller, after the expansion force is tested, the film sensor 3 is taken out, and the novel elastic material 7 is calculated according to a calculation formula.
Claims (6)
1. A method for testing internal pressure of a lithium secondary battery module, comprising:
s1: the method comprises the steps of taking a main battery cell, assembling a thin film sensor with a common elastic material and a steel plate clamp, and then performing charge-discharge cyclic test on the main battery cell;
s2: testing the contact pressure distribution state of the contact surface with the battery cell through a film sensor, and obtaining the cyclic expansion stress sigma of each area of the surface of the main battery cell from the expansion force distribution range of each area of the surface of the main battery cell, wherein the deformation of each area of the surface of the main battery cell is consistent in the charge-discharge cyclic process, namely the strain epsilon is consistent;
s3: calculating a novel elastic material E, E=sigma/epsilon in the module according to the S2 test data;
s4: and assembling each designed novel elastic material into the auxiliary battery core to form a module.
2. The method for testing the internal pressure of a lithium secondary battery module according to claim 1, wherein: in the S1, the thin film sensor is arranged on one side of the main battery cell, the other side of the main battery cell and the outer side of the thin film sensor are provided with common elastic materials, and steel plate clamps are arranged outside the common elastic materials.
3. The method for testing the internal pressure of a lithium secondary battery module according to claim 2, wherein: the thin film sensor can test the expansion pressure of the main battery cell.
4. The method for testing the internal pressure of a lithium secondary battery module according to claim 2, wherein: in the step S4, the module includes:
the battery pack comprises a plurality of auxiliary battery cells which are arranged in parallel, novel elastic materials arranged between the auxiliary battery cells, a module aluminum plate clamp arranged outside the auxiliary battery cells, and a binding belt encircling the auxiliary battery cells, the novel elastic materials and the module aluminum plate clamp.
5. The method for testing the internal pressure of a lithium secondary battery module according to claim 4, wherein: and a busbar is connected between the secondary battery cells.
6. The method for testing the internal pressure of a lithium secondary battery module according to claim 1, wherein: the compressive resistance value of the novel elastic material is obtained by S3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310176163.4A CN116046239A (en) | 2023-02-28 | 2023-02-28 | Method for testing internal pressure of lithium secondary battery module |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310176163.4A CN116046239A (en) | 2023-02-28 | 2023-02-28 | Method for testing internal pressure of lithium secondary battery module |
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| CN116046239A true CN116046239A (en) | 2023-05-02 |
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| CN202310176163.4A Pending CN116046239A (en) | 2023-02-28 | 2023-02-28 | Method for testing internal pressure of lithium secondary battery module |
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- 2023-02-28 CN CN202310176163.4A patent/CN116046239A/en active Pending
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