CN108226803B - Variable extrusion force battery testing method and system - Google Patents
Variable extrusion force battery testing method and system Download PDFInfo
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- CN108226803B CN108226803B CN201810034504.3A CN201810034504A CN108226803B CN 108226803 B CN108226803 B CN 108226803B CN 201810034504 A CN201810034504 A CN 201810034504A CN 108226803 B CN108226803 B CN 108226803B
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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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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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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]
- G01R31/385—Arrangements for measuring battery or accumulator variables
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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Abstract
The embodiment of the invention provides a variable extrusion force battery testing method and system. First, the two batteries apply the same pressing force, respectively, and the pressing force is maintained for a first period of time. And simultaneously charging the first battery to be full, discharging the second battery to be discharged, and recording the first charging electric quantity of the first battery and the ohmic internal resistance and the polarization internal resistance of the two batteries after standing for a second time period. The compressive force was then released and the two cells were allowed to stand again for a second period of time. And after standing, discharging the first battery until the first battery is discharged, charging the second battery to be full, standing the two batteries for a second time period, and recording the second charging capacity of the second battery. And changing the extrusion force and continuing the steps. And obtaining a test result according to the recorded charging capacity, ohmic internal resistance and polarization internal resistance of the first battery and the second battery under different extrusion forces. Therefore, the variable extrusion force endurance test is carried out on the battery, and the battery capacity degradation condition is not tested only through the charging and discharging times.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a variable extrusion force battery testing method and system.
Background
With the continuous development of science and technology, the pollution to the environment is more and more serious. Among them, automobile exhaust is a major source of pollution. And the pure electric vehicles have less or even no exhaust emission, so the research and development of the pure electric vehicles are more and more concerned. The power of the pure electric vehicle is a battery. At present, after a battery is produced and manufactured into a finished product, a general evaluation method is to screen battery parameters through formation charging and discharging times so as to judge whether the finished battery meets the requirements of delivery specifications. With the popularization and application of a large number of pure electric vehicles, the problem of battery charging safety is more and more important, and the battery cannot be tested only through the charging and discharging times.
Disclosure of Invention
In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a method and a system for testing a battery with variable pressing force, which can test the battery by applying different pressing forces to the battery under the charging and discharging conditions, and obtain the test result.
The embodiment of the invention provides a variable extrusion force battery testing method, which comprises the following steps:
after the discharging of the first battery and the charging of the second battery are finished, respectively applying extrusion force to the first battery and the second battery, keeping the extrusion force for a first time period, simultaneously charging the first battery to be full, and discharging the second battery to be discharged;
in the first time period, after the fully charged first battery and the discharged second battery are placed still for a second time period, recording a first charging capacity, a first ohmic internal resistance and a first polarization internal resistance of the first battery and a second ohmic internal resistance and a second polarization internal resistance of the second battery, wherein the second time period is less than the first time period;
releasing the pressing force applied to the first and second batteries, and allowing the first and second batteries to stand for the second period of time;
after standing for the second time period, discharging the first battery until the discharging is finished, standing for the second time period after the discharging is finished, charging the second battery to be full, standing for the second time period after the full charging is finished, and recording the second charging capacity of the second battery;
and changing the extrusion force, repeating the steps, and obtaining a test result according to the first charging electric quantity, the first ohmic internal resistance and the first polarization internal resistance of the first battery and the second charging electric quantity, the second ohmic internal resistance and the second polarization internal resistance of the second battery under different extrusion forces.
In an embodiment of the present invention, after the discharging of the first battery and the charging of the second battery are finished, the method further includes, before the steps of applying the pressing forces to the first battery and the second battery, respectively, maintaining the pressing forces for a first time period, charging the first battery to be fully charged, and discharging the second battery to be fully discharged:
preprocessing the first battery and the second battery to enable the first battery to be in a discharging end state and the second battery to be in a charging end state;
the step of pre-processing the first battery and the second battery comprises:
before the extrusion force is not applied, the first battery is subjected to standard charge and discharge once, and the first charge capacity of the first battery is recorded;
after the first battery is discharged, standing the first battery for the second time period;
and after the second battery is charged, standing for the second time period.
In an embodiment of the present invention, the method further comprises:
and judging whether lithium ion dendrites exist in the battery according to the first charging electric quantity of the first battery and the second charging electric quantity of the second battery with different extrusion forces.
In an embodiment of the present invention, the method further comprises:
respectively obtaining a first ohm internal resistance curve and a first polarization internal resistance curve according to the first ohm internal resistance and the first polarization internal resistance of the first battery under different extrusion forces;
respectively obtaining a second ohmic internal resistance curve and a second polarization internal resistance curve according to a second ohmic internal resistance and a second polarization internal resistance of the second battery under different extrusion forces;
and analyzing the first ohm internal resistance curve and the second ohm internal resistance curve, analyzing the first polarization internal resistance curve and the second polarization internal resistance curve, and judging the state of the battery pole piece.
In an embodiment of the present invention, the method further comprises:
and screening the batteries according to the states of the battery pole pieces.
In an embodiment of the present invention, the manner of applying the pressing force to the first battery and the second battery respectively includes:
and horizontally extruding the first battery and the second battery respectively.
The embodiment of the invention also provides a battery test system with variable extrusion force, which is applied to the method and comprises a control unit, an extrusion unit, a measurement unit and a charging and discharging unit which are electrically connected, wherein the first battery and the second battery are arranged on a test board,
the extrusion unit is used for applying extrusion force to the first battery and the second battery respectively and keeping the first battery and the second battery for a first time period;
the measuring unit is used for measuring a first charging capacity, a first ohm internal resistance and a first polarization internal resistance of the first battery and a second charging capacity, a second ohm internal resistance and a second polarization internal resistance of the second battery;
the charging and discharging unit is used for charging and discharging the first battery and the second battery;
the control unit is used for controlling the working states of the extrusion unit, the measurement unit and the charging and discharging unit, and obtaining a test result according to the first charging electric quantity, the first ohmic internal resistance and the first polarization internal resistance of the first battery and the second charging electric quantity, the second ohmic internal resistance and the second polarization internal resistance of the second battery under different extrusion forces.
In an embodiment of the present invention, the control unit is further configured to perform battery screening according to the first ohmic internal resistance and the first polarization internal resistance of the first battery and the second ohmic internal resistance and the second polarization internal resistance of the second battery under different pressing forces.
In an embodiment of the invention, the system further comprises connectors, the number of the connectors is matched with the number of the batteries,
one end of the connecting piece is electrically connected with the anode or the cathode of the battery, the other end of the connecting piece is electrically connected with the measuring unit, and the measuring unit measures the charging capacity, the ohmic internal resistance and the polarization internal resistance of the battery through the connecting piece.
In the embodiment of the invention, the test board is provided with a contact element electrically connected with the measuring unit, and the contact element is in contact with the positive electrode or the negative electrode of the fixed battery, so that the measuring unit measures the charging capacity, the ohmic internal resistance and the polarization internal resistance of the battery.
Compared with the prior art, the invention has the following beneficial effects:
the embodiment of the invention provides a variable extrusion force battery testing method and system. When the first battery is discharged and the second battery is charged, the same pressing force is applied to the first battery and the second battery, respectively, and the pressing forces are maintained for a first period of time. Charging the first battery to full charge under the condition of applying extrusion force, and standing for the second time period after full charge, wherein the second time period is less than the first time period; and simultaneously discharging the second battery until discharging is finished, and standing for the second time period after discharging is finished. After standing, recording a first charging capacity, a first ohmic internal resistance and a first polarization internal resistance of the first battery; and recording a second ohmic internal resistance and a second polarized internal resistance of the second battery. The compressive force is then released and the first and second batteries are rested for the second period of time again. After the standing is finished, discharging the first battery till the discharging is finished, and standing for the second time period; and charging the second battery to be full, standing for the second time period, and recording the second charging capacity of the second battery. And changing the extrusion force and continuing the steps. And obtaining a test result according to the recorded charging capacity, ohmic internal resistance and polarization internal resistance of the first battery and the second battery under different extrusion forces. Therefore, the variable extrusion force endurance test is carried out on the battery, and the battery capacity degradation condition is not tested only through the charging and discharging times. By the method, not only can the new battery be tested, but also the old battery can be screened through the test.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic flow chart of a battery testing method for variable compression force according to an embodiment of the present invention.
Fig. 2 is a graph of battery charging current, battery voltage, and time.
Fig. 3 is a second schematic flow chart of a battery testing method with variable compression force according to an embodiment of the present invention.
Fig. 4 is a flowchart illustrating sub-steps included in step S110 in fig. 3.
Fig. 5 is a third schematic flow chart of a battery testing method for variable compression force according to an embodiment of the present invention.
Fig. 6 is a block diagram of a battery testing system with variable compression force according to an embodiment of the present invention.
Icon: 100-a battery test system; 110-a control unit; 120-a pressing unit; 130-a measurement unit; 140-charge and discharge unit.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present invention, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.
Some embodiments of the invention are described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.
Referring to fig. 1, fig. 1 is a schematic flow chart of a method for testing a battery with variable compression force according to an embodiment of the present invention. The internal resistance and polarization state of the battery change under compression. In this embodiment, ohmic internal resistance and polarization internal resistance of the battery under different extrusion forces are recorded, and the recorded data are analyzed to obtain a test result. The method for testing the battery with variable pressing force is described in detail below.
In this embodiment, when the first battery and the second battery are both lithium batteries, lithium ions are extracted from the positive electrode and inserted into the negative electrode during the charging process of the batteries, so that the negative electrode expands and the positive electrode reduces in volume; during the discharging process of the battery, lithium ions are extracted from the negative electrode and are inserted into the positive electrode, so that the positive electrode expands and the negative electrode shrinks in volume. The battery test is carried out by utilizing the volume change of the anode and the cathode of the battery and matching with the external extrusion force of the battery at different charging and discharging moments.
In this embodiment, a battery test is performed using the first battery and the second battery. The first battery and the second battery may be different batteries, for example, the first battery is used as a standard battery, the measurement data of the first battery is used as a standard, and the measurement data of the second battery is analyzed to obtain a test result of the second battery.
Step S120, after the discharging of the first battery and the charging of the second battery are finished, respectively applying extrusion forces to the first battery and the second battery, keeping the extrusion forces for a first time period, simultaneously charging the first battery to be full, and discharging the second battery to be finished.
In the present embodiment, after the end of the discharge of the first battery, a pressing force is applied to the first battery, and the first battery is charged to full charge with the pressing force applied. And simultaneously, after the second battery is charged, applying the same extrusion force to the second battery, and discharging the second battery until the second battery is discharged under the condition of applying the extrusion force. Wherein the compressive force is maintained for a first period of time after the compressive force is applied.
In the embodiment of the present embodiment, the pressing force may be applied to the first battery and the second battery, respectively, but is not limited to, horizontal pressing of the first battery and the second battery, respectively.
Wherein, when the extrusion force is the maximum extrusion force, the internal structure of the battery can not collapse and the short circuit fault can not occur. The contact state of the positive electrode and the interface and the contact state of the negative electrode and the interface of the battery in the pressed state are different from those of the battery not in the pressed state. The interior of the battery is usually in a winding, stacking or zigzag shape, and after the battery is subjected to a pressing force, the pressed state of each pole piece in the battery is relatively uniform, so that the internal resistance and the polarization state of the battery can be changed.
Wherein the interface is an SEI (solid electrolyte interface (film)) film, and the SEI film is a passivation film layer having a solid electrolyte property. The SEI is an excellent conductor of lithium ions, and can transmit the lithium ions in the SEI to enter the surface of graphite so as to carry out lithium extraction. Meanwhile, the insulating material is a good electronic insulator, and the internal short-circuit probability can be effectively reduced. The SEI film can effectively prevent the co-intercalation of solvent molecules, avoids the damage to an electrode material caused by the co-intercalation of the solvent molecules, and greatly improves the cycle performance and the service life of the electrode in step S130.
In the present embodiment, with the above-described pressing force applied, the first battery that is fully charged is left to stand for a second period of time, and the second battery that is discharged is also left to stand for the second period of time. And after standing for the second time period, recording the first charging capacity, the first ohmic internal resistance and the first polarization internal resistance of the first battery and the second ohmic internal resistance and the second polarization internal resistance of the second battery. Wherein the second time period is less than the first time period. The first time period and the second time period may be set according to an actual situation, for example, the second time period is 30 min.
Referring to fig. 2, fig. 2 is a graph showing a relationship between a charging current of a battery, a battery voltage and time. The cell voltage of the li-ion cell under the charging pulse will show the curve shown in fig. 2. Vr1, Vr2, Vr3 in fig. 2 are due to the internal resistance of the cell, and the exponential change includes a portion of the cell polarization voltage in addition to the increase in the cell voltage. Therefore, when the extrusion force test is carried out, the ohmic internal resistance and the polarization internal resistance of the battery can be recorded.
Step S140, releasing the pressing force applied to the first battery and the second battery, and allowing the first battery and the second battery to stand for the second period of time.
In this embodiment, after the second period of time of standing, the pressing forces applied to the first and second batteries are released, and after the pressing forces are released, the first and second batteries are again allowed to stand for the second period of time to prepare for the subsequent operation.
And S150, after standing for the second time period, discharging the first battery until the first battery is discharged, standing for the second time period after the first battery is discharged, charging the second battery until the second battery is fully charged, standing for the second time period after the second battery is fully charged, and recording the second charging capacity of the second battery.
In this embodiment, after the end of the second standing, the first battery is discharged to the end of discharging, and is left standing for the second period of time. After the second standing is finished, charging the second battery to be full, and after the second battery is full, standing the second battery for the second time period; and recording the second charging capacity of the second battery after the standing is finished.
And changing the extrusion force, and repeating the steps to obtain the charging capacity, the ohmic internal resistance and the polarization internal resistance of the battery under different extrusion forces. Wherein the pressing force may be changed in a gradually increasing manner.
Step S160, obtaining a test result according to the first charging electric quantity, the first ohmic internal resistance and the first polarization internal resistance of the first battery and the second charging electric quantity, the second ohmic internal resistance and the second polarization internal resistance of the second battery under different extrusion forces.
In this embodiment, one of the first battery and the second battery may be used as a standard, so as to compare measurement data (including the charging capacity, the ohmic internal resistance, and the polarization internal resistance) of the other battery according to the standard charging capacity, the ohmic internal resistance, and the polarization internal resistance, thereby obtaining a test result.
Referring to fig. 3, fig. 3 is a second schematic flow chart of a method for testing a battery with variable compression force according to an embodiment of the present invention. Before step S120, the method may further include step S110.
Step S110, pre-processing the first battery and the second battery.
Referring to fig. 4, fig. 4 is a flowchart illustrating sub-steps included in step S110 in fig. 3. Step S110 may include sub-step S111, sub-step S112, and sub-step S113.
And a substep S111 of performing standard charge and discharge once on the first battery before applying no extrusion force, and recording a first charge capacity of the first battery.
And a substep S112, after the first battery is discharged, standing the first battery for the second time period.
And a substep S113, after the second battery is charged, standing for the second time period.
In the present embodiment, the first charge capacity of the first battery is obtained and recorded by subjecting the first battery to standard charge and discharge before the pressing force is not applied. Then, standing the discharged first battery for the second time period; and after the second battery is charged, standing for the second time period so as to test the battery under the condition of applying extrusion force.
By the method, the variable extrusion force tolerance test can be performed on the new battery, so that the condition that the battery capacity is degenerated only through the charging and discharging times is avoided, and the charging safety of the battery is further ensured.
In this embodiment, one of the first battery and the second battery may include a recycled battery that is utilized in a stepped manner. Through the test, whether the lithium ion dendrite exists in the battery or not can be judged according to the first charging capacity of the first battery and the second charging capacity of the second battery with different extrusion forces. The echelon utilization refers to a continuous use process that a certain used product reaches the original design life and the function of the product is completely or partially recovered by other methods.
When lithium dendrite exists in the battery, the interface states of an SEI film, a positive plate and a negative plate in the battery which are utilized in a gradient manner are changed through the cyclic process of extrusion force application-release-application-release, and after obvious lithium dendrite is extruded, micro short circuit or internal short circuit to a certain degree can be caused. Therefore, whether lithium ion dendrites exist in the battery or not can be judged according to the charging amount of the battery, and the battery is further screened. Therefore, the old battery can be screened according to whether the lithium ion dendrites are stored or not based on the method.
The variable extrusion force test is carried out on the cyclic battery which is utilized in the echelon mode, and an SEI film of a negative electrode graphite layer and electrolyte can be rebuilt. The newly-built SEI film is of significant help for improving the reliability of the lithium ion battery cathode after circulation.
Referring to fig. 5, fig. 5 is a third schematic flow chart of a method for testing a battery with variable compression force according to an embodiment of the present invention. The method may further include step S171, step S172, and step S173.
Step S171 is to obtain a first ohmic internal resistance curve and a first polarized internal resistance curve according to the first ohmic internal resistance and the first polarized internal resistance of the first battery under different extrusion forces, respectively.
Step S172, a second ohmic internal resistance curve and a second polarized internal resistance curve are obtained according to a second ohmic internal resistance and a second polarized internal resistance of the second battery under different extrusion forces, respectively.
Step S173, analyzing the first and second ohmic internal resistance curves, analyzing the first and second polarization internal resistance curves, and determining the state of the battery pole piece.
The ohmic resistance curve and the polarization internal resistance curve of the new battery under different extrusion forces are respectively obviously different from the ohmic resistance curve and the polarization internal resistance curve of the old battery under the same extrusion force. Therefore, the pole piece health state of the battery can be distinguished through the ohm internal resistance curve and the polarization internal resistance curve, and the battery is screened according to the state of the battery pole piece.
In the embodiment of the present embodiment, the battery testing method may be used for, but is not limited to, a ternary lithium battery, a lithium manganate battery, a lithium iron phosphate battery, and the like.
Referring to fig. 6, fig. 6 is a block diagram illustrating a battery testing system 100 with variable compression force according to an embodiment of the present invention. The variable-compression-force battery test system 100 is applied to a variable-compression-force battery test method. The battery test system 100 may include a control unit 110, a compression unit 120, a measurement unit 130, and a charge and discharge unit 140, which are communicatively connected. The first battery and the second battery are arranged on a test board.
The pressing unit 120 is configured to apply pressing forces to the first battery and the second battery, respectively, and maintain the pressing forces for a first period of time.
The measuring unit 130 is configured to measure a first charging capacity, a first ohmic internal resistance and a first polarization internal resistance of the first battery, and a second charging capacity, a second ohmic internal resistance and a second polarization internal resistance of the second battery.
The charge/discharge unit 140 is used to charge and discharge the first battery and the second battery.
The control unit 110 is configured to control the working states of the pressing unit 120, the measuring unit 130, and the charging and discharging unit 140, and obtain a test result according to the first ohmic internal resistance and the first polarized internal resistance of the first battery and the second ohmic internal resistance and the second polarized internal resistance of the second battery under different pressing forces.
In the embodiment of the present invention, the control unit 110 may be a computing device, such as a desktop computer, a controller, and the like.
The control unit 110 is further configured to perform battery screening according to the first ohmic internal resistance and the first polarization internal resistance of the first battery and the second ohmic internal resistance and the second polarization internal resistance of the second battery under different pressing forces.
In one embodiment of this embodiment, the system may further include connectors, and the number of the connectors matches the number of the batteries. When the battery is placed on the test table, one end of the connecting member is electrically connected to the positive electrode or the negative electrode of the battery, and the other end is electrically connected to the measuring unit 130. The measurement unit 130 measures the charging capacity, ohmic internal resistance and polarization internal resistance of the battery through the connection member.
In another embodiment of this embodiment, the test platform is provided with a contact electrically connected to the measurement unit 130, and the contact is in contact with the positive electrode or the negative electrode of the fixed battery. Through the above resetting, the measurement unit 130 can measure the charging capacity, the ohmic internal resistance and the polarization internal resistance of the battery.
In an embodiment of this embodiment, the charging and discharging unit 140 may charge the battery through a connection line or other means.
In summary, the embodiments of the present invention provide a method and a system for testing a battery with variable compression force. When the first battery is discharged and the second battery is charged, the same pressing force is applied to the first battery and the second battery, respectively, and the pressing forces are maintained for a first period of time. Charging the first battery to full charge under the condition of applying extrusion force, and standing for the second time period after full charge, wherein the second time period is less than the first time period; and simultaneously discharging the second battery until discharging is finished, and standing for the second time period after discharging is finished. After standing, recording a first charging capacity, a first ohmic internal resistance and a first polarization internal resistance of the first battery; and recording a second ohmic internal resistance and a second polarized internal resistance of the second battery. The compressive force is then released and the first and second batteries are rested for the second period of time again. After the standing is finished, discharging the first battery till the discharging is finished, and standing for the second time period; and charging the second battery to be full, standing for the second time period, and recording the second charging capacity of the second battery. And changing the extrusion force and continuing the steps. And obtaining a test result according to the recorded charging capacity, ohmic internal resistance and polarization internal resistance of the first battery and the second battery under different extrusion forces. Therefore, the variable extrusion force endurance test is carried out on the battery, and the battery capacity degradation condition is not tested only through the charging and discharging times. By the method, not only can the new battery be tested, but also the old battery can be screened.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A variable crush force battery test method, comprising:
after the discharging of the first battery and the charging of the second battery are finished, respectively applying extrusion force to the first battery and the second battery, keeping the extrusion force for a first time period, simultaneously charging the first battery to be full, and discharging the second battery to be discharged;
in the first time period, after the fully charged first battery and the discharged second battery are placed still for a second time period, recording a first charging capacity, a first ohmic internal resistance and a first polarization internal resistance of the first battery and a second ohmic internal resistance and a second polarization internal resistance of the second battery, wherein the second time period is less than the first time period;
releasing the pressing force applied to the first and second batteries, and allowing the first and second batteries to stand for the second period of time;
after standing for the second time period, discharging the first battery until the discharging is finished, standing for the second time period after the discharging is finished, charging the second battery to be full, standing for the second time period after the full charging is finished, and recording the second charging capacity of the second battery;
and changing the extrusion force, repeating the steps, and obtaining a test result according to the first charging electric quantity, the first ohmic internal resistance and the first polarization internal resistance of the first battery and the second charging electric quantity, the second ohmic internal resistance and the second polarization internal resistance of the second battery under different extrusion forces.
2. The method of claim 1, wherein after the discharging of the first battery and the charging of the second battery are completed, applying a pressing force to the first battery and the second battery, respectively, and maintaining the pressing forces for a first period of time while the first battery is fully charged and the second battery is discharged until the discharging is completed, the method further comprises:
preprocessing the first battery and the second battery to enable the first battery to be in a discharging end state and the second battery to be in a charging end state;
the step of pre-processing the first battery and the second battery comprises:
before the extrusion force is not applied, the first battery is subjected to standard charge and discharge once, and the first charge capacity of the first battery is recorded;
after the first battery is discharged, standing the first battery for the second time period;
and after the second battery is charged, standing for the second time period.
3. The method of claim 1, further comprising:
and judging whether lithium ion dendrites exist in the battery according to the first charging electric quantity of the first battery and the second charging electric quantity of the second battery with different extrusion forces.
4. The method of claim 1, further comprising:
respectively obtaining a first ohm internal resistance curve and a first polarization internal resistance curve according to the first ohm internal resistance and the first polarization internal resistance of the first battery under different extrusion forces;
respectively obtaining a second ohmic internal resistance curve and a second polarization internal resistance curve according to a second ohmic internal resistance and a second polarization internal resistance of the second battery under different extrusion forces;
and analyzing the first ohm internal resistance curve and the second ohm internal resistance curve, analyzing the first polarization internal resistance curve and the second polarization internal resistance curve, and judging the state of the battery pole piece.
5. The method of claim 4, further comprising:
and screening the batteries according to the states of the battery pole pieces.
6. The method of claim 1, wherein the applying the compressive force to the first battery and the second battery respectively comprises:
and horizontally extruding the first battery and the second battery respectively.
7. A variable-extrusion-force battery testing system applied to the method of any one of claims 1-6, the system comprising a control unit, an extrusion unit, a measurement unit and a charging and discharging unit which are electrically connected, wherein the first battery and the second battery are arranged on a testing platform,
the extrusion unit is used for applying extrusion force to the first battery and the second battery respectively and keeping the first battery and the second battery for a first time period;
the measuring unit is used for measuring a first charging capacity, a first ohm internal resistance and a first polarization internal resistance of the first battery and a second charging capacity, a second ohm internal resistance and a second polarization internal resistance of the second battery;
the charging and discharging unit is used for charging and discharging the first battery and the second battery;
the control unit is used for controlling the working states of the extrusion unit, the measurement unit and the charging and discharging unit, and obtaining a test result according to the first charging electric quantity, the first ohmic internal resistance and the first polarization internal resistance of the first battery and the second charging electric quantity, the second ohmic internal resistance and the second polarization internal resistance of the second battery under different extrusion forces.
8. The system of claim 7, wherein the control unit is further configured to perform cell screening based on the first ohmic internal resistance and the first polarization internal resistance of the first cell and the second ohmic internal resistance and the second polarization internal resistance of the second cell at different compressive forces.
9. The system of claim 7, further comprising a number of connectors matching a number of batteries,
one end of the connecting piece is electrically connected with the anode or the cathode of the battery, the other end of the connecting piece is electrically connected with the measuring unit, and the measuring unit measures the charging capacity, the ohmic internal resistance and the polarization internal resistance of the battery through the connecting piece.
10. The system of claim 7, wherein the testing platform is provided with a contact member electrically connected with the measuring unit, and the contact member is in contact with the positive electrode or the negative electrode of the fixed battery, so that the measuring unit can measure the charging capacity, the ohmic internal resistance and the polarization internal resistance of the battery.
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| CN110850310B (en) * | 2019-12-20 | 2022-04-15 | 东软睿驰汽车技术（沈阳）有限公司 | Battery safety testing method and device |
| CN111999667B (en) * | 2020-08-21 | 2023-05-30 | 惠州亿纬锂能股份有限公司 | Evaluation method of internal resistance of battery |
| CN113325318B (en) * | 2021-04-30 | 2022-12-13 | 上海空间电源研究所 | Lithium ion storage battery consistency screening method |
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| CN101452057B (en) * | 2007-12-07 | 2012-06-20 | 株式会社Ntt都科摩 | Battery testing device and battery testing method |
| CN201251621Y (en) * | 2008-08-15 | 2009-06-03 | 天津力神电池股份有限公司 | Detection device for voltage internal resistance of steady pressure lithium ion battery |
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