CN116338477A - Battery expansion force influence factor testing and analyzing method - Google Patents
Battery expansion force influence factor testing and analyzing method Download PDFInfo
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- CN116338477A CN116338477A CN202310324661.9A CN202310324661A CN116338477A CN 116338477 A CN116338477 A CN 116338477A CN 202310324661 A CN202310324661 A CN 202310324661A CN 116338477 A CN116338477 A CN 116338477A
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- 238000012360 testing method Methods 0.000 title claims abstract description 68
- 238000000034 method Methods 0.000 title claims abstract description 50
- 230000008569 process Effects 0.000 claims abstract description 31
- 230000002238 attenuated effect Effects 0.000 claims abstract description 9
- 238000012544 monitoring process Methods 0.000 claims abstract description 5
- 230000002441 reversible effect Effects 0.000 claims description 31
- 230000002427 irreversible effect Effects 0.000 claims description 20
- 230000008859 change Effects 0.000 claims description 18
- 238000007599 discharging Methods 0.000 claims description 15
- 230000008961 swelling Effects 0.000 claims description 10
- 239000010405 anode material Substances 0.000 claims description 7
- 239000010406 cathode material Substances 0.000 claims description 7
- 230000007613 environmental effect Effects 0.000 claims description 6
- 230000002829 reductive effect Effects 0.000 abstract description 8
- 238000002474 experimental method Methods 0.000 abstract description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 22
- 229910052744 lithium Inorganic materials 0.000 description 22
- 239000002245 particle Substances 0.000 description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 230000036541 health Effects 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000003411 electrode reaction Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910003063 Li1−xCoO2 Inorganic materials 0.000 description 1
- 241000238367 Mya arenaria Species 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000003862 health status Effects 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
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- 239000007788 liquid Substances 0.000 description 1
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- 230000004048 modification Effects 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
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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]
- G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
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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]
- G01R31/392—Determining battery ageing or deterioration, e.g. state of health
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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
Abstract
The invention provides a battery expansion force influence factor testing and analyzing method, which comprises the steps of selecting a plurality of groups of batteries in the same batch, carrying out a charge-discharge test by changing test conditions of each group of batteries until the battery capacity is attenuated to 80% of rated capacity, wherein the test conditions comprise ambient temperature, charge-discharge multiplying power and pretightening force, monitoring and recording expansion force values, cycle times and battery capacities corresponding to the cycle times in the cycle charge-discharge process of the plurality of groups of batteries, drawing a battery capacity-cycle times curve, an expansion force-cycle times curve and an expansion force-battery capacity curve of each group of batteries, and analyzing. According to the invention, the battery expansion force influence factors are tested and analyzed in a multi-group cross experiment mode, so that the control of various variables is realized, and the experimental sample size is reduced.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a battery expansion force influence factor testing and analyzing method.
Background
When the lithium battery is used as an energy carrier, chemical reaction and material deformation occur at any time in the lithium battery, so that the shape of the lithium battery continuously changes along with the use state. Both the hard and soft shell materials of lithium batteries have a certain ductility, and a series of physical and chemical changes can form pressure effects inside the lithium battery in the early stages of thermal runaway of the lithium battery. Over time, lithium batteries can expand significantly causing significant pressure changes between the cells.
The expansion of the lithium battery can be divided into reversible deformation and irreversible deformation, and the influence factors of the reversible deformation and the irreversible deformation are numerous, so that a large amount of data support is needed for analyzing the influence of the expansion force on the cycle life of the battery, and if the test scheme is unreasonable, the number of test samples is excessive, so that waste is caused.
Disclosure of Invention
The invention aims at overcoming the defects of the prior art and provides a method for testing and analyzing the influence factors of the expansion force of a battery.
The invention provides a battery expansion force influence factor testing and analyzing method, which comprises the steps of selecting a plurality of groups of batteries in the same batch, carrying out a charge-discharge test by changing test conditions of each group of batteries until the battery capacity is attenuated to 80% of rated capacity, wherein the test conditions comprise ambient temperature, charge-discharge multiplying power and pretightening force, monitoring and recording expansion force values, cycle times and battery capacities corresponding to the cycle times in the cycle charge-discharge process of the plurality of groups of batteries, and drawing and analyzing battery capacity-cycle times curves, expansion force-cycle times curves and expansion force-battery capacity curves of the batteries of each group;
the number of the battery packs is at least six, the first battery pack and the second battery pack are different in only ambient temperature, the third battery pack and the fourth battery pack are different in only ambient temperature, the first battery pack and the third battery pack are different in only charge and discharge multiplying power, the second battery pack and the fourth battery pack are different in only charge and discharge multiplying power, and the first battery pack, the fifth battery pack and the sixth battery pack are different in only initial pretightening force.
The six groups of batteries are mutually crossed experiments, and control over various variables is realized through a crossed comparison mode, so that the experimental sample size is reduced, the experimental cost is reduced, and the influences of charge and discharge multiplying power, charge and discharge temperature, cycle times, pretightening force and battery health state on the battery expansion force and the relationship between the expansion force and the battery service life can be analyzed and verified through analysis of a battery capacity-cycle number curve, an expansion force-cycle number curve and an expansion force-battery capacity curve, so that theoretical basis is provided for adjustment of a battery thermal management scheme and a charge and discharge strategy, and the cycle life of the battery is improved.
Further, the test conditions for the first set of cells were: the charge-discharge multiplying power is 1C, the initial pretightening force is 300kg, and the ambient temperature is 25+/-2 ℃;
the test conditions for the second set of cells were: the charge-discharge multiplying power is 1C, the initial pretightening force is 300kg, and the ambient temperature is 45+/-2 ℃;
the test conditions for the third set of cells were: the charge-discharge multiplying power is 1/3C, the initial pretightening force is 300kg, and the ambient temperature is 25+/-2 ℃;
the test conditions for the fourth set of cells were: the charge-discharge multiplying power is 1/3C, the initial pretightening force is 300kg, and the ambient temperature is 45+/-2 ℃;
the test conditions for the fifth set of cells were: the charge-discharge multiplying power is 1C, the initial pretightening force is 400kg, and the ambient temperature is 25+/-2 ℃;
the test conditions for the sixth set of cells were: the charge-discharge multiplying power is 1C, the initial pretightening force is 200kg, and the ambient temperature is 25+/-2 ℃;
the rest time of the six groups of cells was the same.
The environment temperature is 25+/-2 ℃ and 45+/-2 ℃, the 25+/-2 ℃ is the normal working temperature, the 45+/-2 ℃ is the higher working temperature, and the two temperatures are representative, and the charge and discharge multiplying power 1C and 1/3C are common multiplying power, so that the test scheme is representative, and the test result has great reference significance.
Further, according to the battery capacity-cycle number curves of the first group of batteries and the second group of batteries, comparing the capacities of the two groups of batteries under the same cycle number, and analyzing the influence of the ambient temperature on the service life of the batteries; according to the expansion force-cycle number curve and the expansion force-battery capacity curve of the first battery and the second battery, comparing the expansion force of the two batteries under the same cycle number, comparing the expansion force of the two batteries under the same battery capacity, and analyzing the influence of the environmental temperature on the irreversible deformation of the batteries.
And the influence of temperature on the service life of the battery and the expansion force of the battery can be obtained through analysis of test data of the first battery and the second battery, so that a reference is provided for the design of a battery thermal management scheme.
Further, according to the battery capacity-cycle number curves of the first battery and the third battery, comparing the capacities of the two batteries under the same cycle number, analyzing the influence of the charge-discharge multiplying power on the service life of the battery, according to the expansion force-cycle number curves and the expansion force-battery capacity curves of the first battery and the third battery, comparing the expansion force of the two batteries under the same cycle number, comparing the expansion force of the two batteries under the same battery capacity, and analyzing the influence of the charge-discharge multiplying power on the irreversible deformation of the battery;
according to the battery capacity-cycle number curves of the second battery and the fourth battery, comparing the capacity of the two batteries under the same cycle number, analyzing the influence of the charge-discharge multiplying power on the service life of the battery, according to the expansion force-cycle number curves of the second battery and the fourth battery and the expansion force-battery capacity curves, comparing the expansion force of the two batteries under the same cycle number, comparing the expansion force of the two batteries under the same battery capacity, and analyzing the influence of the charge-discharge multiplying power on the irreversible deformation of the battery.
By analyzing the test data of the first four groups of batteries, the influence of changing the charge-discharge multiplying power at each ambient temperature on the service life of the battery and irreversible deformation of the battery can be obtained, and the battery can have longer service life and smaller expansion force due to the fact that the charge-discharge multiplying power is adopted at a certain temperature, so that a reference is provided for the design of a charge-discharge strategy.
Further, according to the battery capacity-cycle number curves of the first battery and the third battery and the second battery and the fourth battery, comparing the difference value of the two battery capacities of the first battery and the third battery under the same cycle number with the difference value of the two battery capacities of the second battery and the fourth battery under the same cycle number, and analyzing the influence of changing the charge-discharge multiplying power of the battery under different environment temperatures on the service life of the battery;
according to the expansion force-cycle number curve and the expansion force-battery capacity curve of the first battery and the third battery and the second battery and the fourth battery, comparing the difference value of the expansion forces of the first battery and the third battery under the same cycle number with the difference value of the expansion forces of the second battery and the fourth battery under the same cycle number, comparing the difference value of the expansion forces of the first battery and the third battery under the same battery capacity with the difference value of the expansion forces of the second battery and the fourth battery under the same battery capacity, and analyzing the influence of changing charge and discharge multiplying power on the expansion forces of the batteries under different environment temperatures.
By analyzing the test data of the first four groups of batteries, the influence of changing the charge-discharge multiplying power on the service life of the batteries and irreversible deformation of the batteries at different ambient temperatures can be obtained, and the battery is longer in service life and smaller in expansion force due to the fact that the charge-discharge multiplying power is adopted at different temperatures, so that a reference is provided for the design of charge-discharge strategies.
Further, according to the battery capacity-cycle number curves of the first group battery, the fifth group battery and the sixth group battery, the sizes of the battery capacities of the first group battery, the fifth group battery and the sixth group battery under the same cycle number are compared, and the influence of different pretightening forces on the service life of the battery is analyzed.
And the influence of the pretightening force on the service life of the battery can be obtained by analyzing the test data of the first group, the fifth group and the sixth group of batteries, so that a reference is provided for the design of the pretightening force of the battery.
Further, drawing corresponding expansion force-SOC curves of each group of batteries in different SOHs, comparing the expansion force of the group of batteries in different SOHs, and analyzing the change condition of reversible deformation of the group of batteries in different SOHs.
According to the corresponding expansion force-SOC curve of each group of batteries in different SOH, the change condition of reversible deformation of the batteries after reaching a certain cycle number or a certain health state under the corresponding test conditions can be analyzed.
Further, the change condition of the battery expansion force in one charge and discharge process of the first battery and the second battery in each SOH is compared, the influence of the battery on the reversible deformation of the battery in the environment temperature of different SOHs is analyzed, the change condition of the battery expansion force in one charge and discharge process of the first battery and the third battery in each SOH is compared, the influence of the battery charge and discharge multiplying power in different SOHs on the reversible deformation of the battery is analyzed, the change condition of the battery expansion force in one charge and discharge process of the first battery, the fifth battery and the sixth battery in each SOH is compared, and the influence of the pretightening force of the battery in different SOHs on the reversible deformation of the battery is analyzed.
The magnitude of the influence of the ambient temperature, the charge-discharge multiplying power and the pretightening force on the reversible deformation of the battery can be obtained by respectively comparing the test data of the first group, the second group, the first group, the third group, the first group, the fifth group and the sixth group of batteries.
Further, according to the expansion force-SOC curve of each group of batteries, the difference between the maximum value and the minimum value of the expansion force of each group of batteries in a charging and discharging process of each group of batteries in different SOHs is calculated, and the most sensitive factor of reversible deformation of the batteries in different SOHs is analyzed.
By comparing the difference between the maximum and minimum values of the expansion force of the batteries in a charge and discharge process when the batteries are different from each other, the external factors which most easily affect the reversible deformation of the batteries can be obtained.
Further, the method also comprises the step of performing charge and discharge tests by using batteries with different anode and cathode materials.
The battery with different anode and cathode materials is arranged for charge and discharge test, so that the influence of the different anode and cathode materials on the battery expansion force and the cycle life can be analyzed, a more suitable material is found, the influence of external factors on the battery life can be reduced, and the battery expansion force can be ensured to be in a proper range.
The beneficial effects of the invention are as follows: the battery expansion force influence factors are tested and analyzed in a multi-group cross experiment mode, so that the relations among temperature, charge-discharge multiplying power, cycle times, expansion force, battery capacity, capacity retention rate and capacity attenuation rate can be obtained, control of various variables is realized, and the experimental sample size is reduced. The optimal scheme for prolonging the cycle life of the battery and the adjustment basis for the charging and discharging strategies of the battery thermal management scheme can be obtained by analyzing the influence factors of the expansion force of the battery, and the personal and property loss of the lithium battery caused by thermal runaway is reduced.
Drawings
FIG. 1 is a graph of expansion force versus SOC during charging of a first battery pack according to an embodiment of the present invention;
fig. 2 is an expansion force-SOC curve during discharge of the first battery pack in an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved by the present application more clear, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
The expansion of lithium batteries includes reversible deformation and irreversible deformation.
The reaction principle of the lithium battery is as follows: positive electrode reaction: liCoO2→Li1-xCoO2+xLi++ xe (electrons), negative electrode reaction: the reversible deformation of the battery in the use process is mainly related to the quantity of lithium ions participating in the charge and discharge process, and in the lithium battery charging process, the distance between graphite lattices in the negative electrode is continuously increased due to the movement of the lithium ions between the positive electrode and the negative electrode, so that the internal stress generated between the lattices is larger and larger, and the negative electrode is expanded in the process to cause the swelling of the lithium battery. During the discharge process, lithium ions in the negative electrode start to be dissociated back to the positive electrode, and the original shape of the lithium battery is restored. Namely, the influence factors of the reversible expansion of the lithium battery are as follows: charge-discharge rate, state of health (SOH) of lithium battery, different positive electrode materials.
Irreversible expansion of lithium batteries includes gas expansion, SEI film growth, active particle and pole piece breakage:
1. the gas expansion, which is associated with different degrees throughout the normal charge and discharge cycle, is accompanied by a lithium battery in which the electrolyte decomposes into the most predominant gas generating reaction, which is exacerbated by an increase in temperature. The main contributors to gas production expansion include: charge-discharge temperature, charge-discharge multiplying power and electrolyte.
2. The SEI film grows, the thickness of the SEI film increases with the increase of charge and discharge cycles, and meanwhile, the liberation of electrons is restrained, so that the growth speed of the SEI film is reduced. From this, the main influencing factors of SEI film growth include: and the cycle times are increased, the charge-discharge multiplying power and the charge-discharge temperature are increased.
3. Active particles and pole pieces break: in the process of recycling the battery, the structural damage of the anode plate and the breakage of active material particles caused by the movement of lithium removal and lithium intercalation are important reasons for causing irreversible deformation of the lithium battery. The main factors of the breakage of the active particles and the pole pieces include the cycle times, the charge-discharge multiplying power and the core materials (binder and electrode materials).
4. When the batteries are grouped, a pretightening force is given to the batteries, different effects can be caused by the pretightening force or not and different pretightening forces, and if the pretightening force is too large, when the batteries are expanded and lack of constraint, once one battery cell is out of control, the battery cell can explode rapidly. Different pre-pressures have different effects on battery life.
In connection with the above analysis, the test protocol of this example is as follows:
the method comprises the steps of selecting the batteries in the same batch to be equally divided into six groups for charge and discharge cycle test, monitoring and recording the expansion force of each group of batteries at any time by using an expansion force testing device, wherein the rest time of the six groups of batteries is the same as one hour, the rest time refers to the rest time which is required to be passed for a period of time after the batteries are charged or discharged in the normal charge and discharge process of the batteries, the rest time is customized according to the strategy of a battery manufacturer, and the rest time is a process of cooling and cooling recovery of the batteries, so that the influence of the change of the temperature on test results caused by the charge and discharge of the batteries can be prevented.
A first group: charging and discharging multiplying power 1C, shelf time 1h, initial pretightening force 300kg, and charging and discharging circulation at 25+/-2 ℃ environment temperature until the battery capacity is attenuated to 80% of rated capacity.
Second group: charging and discharging multiplying power 1C, shelf time 1h, initial pretightening force 300kg, and charging and discharging circulation at 45+/-2 ℃ environment temperature until the battery capacity is attenuated to 80% of rated capacity.
Third group: the charge-discharge multiplying power is 1/3C, the rest time is 1h, the initial pretightening force is 300kg, and the charge-discharge cycle is carried out at the ambient temperature of 25+/-2 ℃ until the battery capacity is attenuated to 80% of the rated capacity.
Fourth group: the charge-discharge multiplying power is 1/3C, the rest time is 1h, the initial pretightening force is 300kg, and the charge-discharge cycle is carried out at the ambient temperature of 45+/-2 ℃ until the battery capacity is attenuated to 80% of the rated capacity.
Fifth group: charging and discharging multiplying power 1C, at room temperature 25+/-2 ℃, resting time 1h, pretightening force 400kg, and charging and discharging circulation at the ambient temperature of 25+/-2 ℃ until the battery capacity is attenuated to 80% of rated capacity.
Sixth group: charging and discharging multiplying power 1C, placing for 1h at room temperature 25+/-2 ℃, pretightening force 200kg, and performing charging and discharging circulation at the ambient temperature of 25+/-2 ℃ until the battery capacity is attenuated to 80% of rated capacity.
And monitoring and recording the temperature, the pressure difference, the capacity, the cycle times, the expansion force and the charge and discharge energy of the six groups of batteries in the charge and discharge process in the test process.
Because the temperature change of the battery is large in the charging and discharging process, the temperature of the battery is controlled by adjusting the water temperature and the flow rate through liquid cooling in the whole test process, the battery is ensured to be at a given ambient temperature, and the accuracy of the test result is ensured.
Because the test object is a semi-finished product module, the single voltage of each cell needs to be monitored, the cell voltage difference is ensured not to be overlarge, and the static voltage differences of the discharge end, the charge end and the rest of six groups of test samples are basically equivalent, so that the consistency of the test sample modules is ensured to be basically the same.
The charge and discharge energy is monitored to determine the energy decay after the battery is cycled and aged and to compare with the battery expansion data.
The test conditions for each set are shown in the following table:
cross-contrast analysis was performed on six groups of experiments after completion of the six groups:
and drawing capacity-cycle number curves, expansion force-cycle number curves and expansion force-battery capacity curves of the two groups according to the first group and the second group of test data.
According to the battery capacity-cycle number curves of the first group of batteries and the second group of batteries, comparing the capacities of the two groups of batteries under the same cycle number, for example, comparing the battery capacities of the first group of batteries and the second group of batteries after the 500 th charge and discharge are completed, analyzing the influence of two environment temperatures of 25+/-2 ℃ and 45+/-2 ℃ on the service life of the batteries, and indicating that the environment temperature is the optimal temperature when the battery capacities are larger under the same cycle number;
according to the expansion force-cycle number curve and the expansion force-battery capacity curve of the first battery and the second battery, the expansion force of the two batteries under the same cycle number and the expansion force of the two batteries under the same battery capacity are compared, for example, the expansion force of the first battery and the expansion force of the second battery after the 500 th charge and discharge are compared, and the expansion force of the first battery and the expansion force of the second battery when the battery capacity is 90% of the rated capacity are compared, the influence of the environmental temperature on the irreversible deformation of the battery is analyzed, and the smaller expansion force of the battery under the same cycle number or the same battery capacity can ensure the safety of the battery and prevent the thermal runaway of the battery.
It should be noted that, the expansion force of the battery after each charge-discharge cycle is not completely restored to the magnitude before the cycle, because at least one of gas expansion, SEI film growth, active particles and pole piece breakage may occur in the battery during the charge-discharge process, the battery is irreversibly deformed, so that the irreversible deformation of the battery can be analyzed according to the expansion force-cycle number curve and the expansion force-battery capacity curve.
And drawing capacity-cycle number curves, expansion force-cycle number curves and expansion force-battery capacity curves of the two groups according to the test data of the first group and the third group of batteries.
And comparing the capacity of the two groups of batteries under the same cycle times according to the battery capacity-cycle times curves of the first group of batteries and the third group of batteries, and analyzing the influence of the charge-discharge multiplying power on the service life of the batteries.
And comparing the expansion forces of the two groups of batteries under the same cycle times according to the expansion force-cycle times curves and the expansion force-battery capacity curves of the first group of batteries and the third group of batteries, comparing the expansion forces of the two groups of batteries under the same battery capacity, and analyzing the influence of charge and discharge multiplying power on irreversible deformation of the batteries.
And drawing capacity-cycle number curves, expansion force-cycle number curves and expansion force-battery capacity curves of the two groups according to the test data of the second group of batteries and the fourth group of batteries.
And comparing the capacity of the two groups of batteries under the same cycle times according to the battery capacity-cycle times curves of the second group of batteries and the fourth group of batteries, and analyzing the influence of the charge-discharge multiplying power on the service life of the batteries.
And comparing the expansion forces of the two groups of batteries under the same cycle times according to the expansion force-cycle times curve and the expansion force-battery capacity curve of the second group of batteries and the fourth group of batteries, comparing the expansion forces of the two groups of batteries under the same battery capacity, and analyzing the influence of charge and discharge multiplying power on irreversible deformation of the batteries.
Comparing the difference value of the capacities of the first group battery and the third group battery under the same cycle times with the difference value of the capacities of the second group battery and the fourth group battery under the same cycle times according to the battery capacity-cycle times curves of the first group battery and the third group battery and the second group battery and the fourth group battery, and analyzing the influence of the change of the charge-discharge multiplying power of the battery under different environment temperatures on the service life of the battery; for example, the difference between the capacities of the first group of batteries and the third group of batteries with the cycle times of 500 is compared with the difference between the capacities of the second group of batteries and the fourth group of batteries with the cycle times of 500, so that the influence of the change of the charge-discharge multiplying power on the service life of the batteries when the temperature is different can be obtained; in addition, the difference value of the capacities of the first group of batteries and the second group of batteries under the same cycle times can be compared with the difference value of the capacities of the third group of batteries and the fourth group of batteries under the same cycle times, and the influence of changing the ambient temperature of the batteries under different charge and discharge multiplying factors on the service life of the batteries is analyzed.
According to the expansion force-cycle number curve and the expansion force-battery capacity curve of the first battery and the third battery and the second battery and the fourth battery, the difference value of the expansion forces of the first battery and the third battery and the difference value of the expansion forces of the second battery and the fourth battery are compared under the same cycle number, the difference value of the expansion forces of the first battery and the third battery and the difference value of the expansion forces of the second battery and the fourth battery are compared under the same battery capacity, and the influence of changing charge and discharge multiplying power on the expansion forces of the batteries under different environment temperatures is analyzed. For example, the difference value of the expansion forces of the first group of batteries and the third group of batteries with the cycle times of 500 is compared with the difference value of the expansion forces of the second group of batteries and the fourth group of batteries with the cycle times of 500, so that the influence of changing the charge-discharge multiplying power on the service life of the batteries when the temperatures are different can be obtained; comparing the difference value of the expansion forces of the first group of batteries and the third group of batteries with the battery capacity being 90% of the rated capacity with the difference value of the expansion forces of the second group of batteries and the fourth group of batteries with the battery capacity being 90% of the rated capacity, and obtaining the influence of the change of the charge-discharge multiplying power on the service life of the batteries when the temperature is different; in addition, the difference value of the expansion forces of the two groups of batteries of the first group of batteries and the second group of batteries under the same cycle times can be compared with the difference value of the expansion forces of the two groups of batteries of the third group of batteries and the fourth group of batteries under the same cycle times, and the influence of changing the environment temperature of the batteries under different charge and discharge multiplying powers on the expansion forces of the batteries is analyzed.
And drawing a battery capacity-cycle number curve according to test data of the first group, the fifth group and the sixth group of batteries, comparing the sizes of the battery capacities of the first group, the fifth group and the sixth group of batteries under the same cycle number, and analyzing the influence of different pretightening forces on the service life of the batteries.
Battery SOH is the degree of battery health, which can be understood as the percentage of the current capacity of the battery to the factory capacity.
According to the first group of experimental data, expansion force-SOC curves when SOH is 100%, 95%, 90%, 85% and 80% are selected, and the relationship between different SOHs and reversible deformation of the battery under the conditions of 25 ℃ and 1C charge-discharge multiplying power and pretightening force of 300kg is analyzed.
As shown in fig. 1, the curves in the figure are respectively expansion force-SOC curves of 1 st, 100 th, 200 th, 300 th, 400 th and 500 th in charging from bottom to top, and as shown in fig. 2, the curves in the figure are respectively expansion force-SOC curves of 1 st, 100 th, 200 th, 300 th, 400 th and 500 th in discharging from bottom to top, and the battery is reversibly deformed due to the back and forth movement of lithium ions between the positive electrode and the negative electrode in the charging and discharging process, so that the size of the reversible deformation of the battery in different SOH states can be observed through the expansion force-SOC curves.
According to the second group of experimental data, expansion force-SOC curves when SOH is 100%, 95%, 90%, 85% and 80% are selected, and the relationship between different SOHs and reversible deformation of the battery under the conditions of 45 ℃ and 1C charge-discharge multiplying power and pretightening force of 300kg is analyzed.
According to the third group of experimental data, expansion force-SOC curves when SOH is 100%, 95%, 90%, 85% and 80% are selected, and the relation between different SOHs and reversible deformation of the battery under the conditions of 25 ℃ and a 1/3C charge-discharge multiplying power and a pretightening force of 300kg is analyzed.
According to the fourth group of experimental data, expansion force-SOC curves when SOH is 100%, 95%, 90%, 85% and 80% are selected, and the relationship between different SOHs and reversible deformation of the battery under the conditions of 45 ℃ and 1C charge-discharge multiplying power and pretightening force of 300kg is analyzed.
According to the fifth group of experimental data, expansion force-SOC curves when SOH is 100%, 95%, 90%, 85% and 80% are selected, and the relation between different SOHs and reversible deformation of the battery under the conditions of 25 ℃ and 1C charge-discharge multiplying power and pretightening force of 400kg is analyzed.
According to the sixth group of experimental data, expansion force-SOC curves when SOH is 100%, 95%, 90%, 85% and 80% are selected, and the relation between different SOHs and reversible deformation of the battery under the conditions of 25 ℃ and 1C charge-discharge multiplying power and pretightening force of 200kg is analyzed.
As the irreversible deformation of the battery is gradually accumulated along with the increase of the charge and discharge cycle times, the reversible deformation of the battery can be represented by taking the expansion force of the battery at different stages (SOH is 100%, 95%, 90%, 85%, 80%); while the expansion force of the battery during the entire cycle decays to 80% of rated capacity is indicative of irreversible deformation.
Comparing the change condition of battery expansion force in one charge and discharge process of the first battery and the second battery in each SOH, analyzing the size of the influence of the battery on the reversible deformation of the battery due to the environmental temperature in different SOHs, comparing the change condition of battery expansion force in one charge and discharge process of the first battery and the third battery in each SOH, analyzing the size of the influence of the charge and discharge multiplying power of the battery on the reversible deformation of the battery in different SOHs, comparing the change condition of battery expansion force in one charge and discharge process of the first battery, the fifth battery and the sixth battery in each SOH, and analyzing the size of the influence of the pretightening force of the battery on the reversible deformation of the battery in different SOHs. The above-mentioned variation includes the variation speed of the expansion force, the maximum value and the minimum value of the expansion force, and the like.
According to the expansion force-SOC curve of each group of batteries, calculating the difference between the maximum value and the minimum value of the expansion force of each group of batteries in a charging and discharging process of each group of batteries in different SOHs, and analyzing the most sensitive factor of reversible deformation of the batteries in different SOHs. For example, the difference between the maximum value and the minimum value of the expansion force of the batteries in one charge and discharge process when the SOH of the first, second, third, fifth and sixth batteries is 90% is calculated, the difference between the batteries in each group is compared based on the first group, and a group with the largest difference can be obtained by analysis.
Six sets of tests can be performed simultaneously, however, the six sets of tests must all be completed to obtain complete data.
In addition, the test can be further provided with six groups of batteries, and the anode and cathode materials of the six groups of batteries are different from those of the six groups of batteries, so that the influence of different anode and cathode materials on the expansion force and the cycle life of the battery is analyzed, a more suitable material is found, the influence of external factors on the service life of the battery can be reduced, and the expansion force of the battery can be ensured to be in a proper range.
In addition to the influences of battery electrolyte, a diaphragm and anode and cathode materials, the expansion factors of the lithium battery comprise influences of battery charge-discharge multiplying power, charge-discharge temperature, cycle times, pretightening force and battery health status, and the batteries are related to the factors in both reversible deformation and irreversible deformation.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.
Claims (10)
1. A battery expansion force influence factor testing and analyzing method is characterized in that: selecting a plurality of groups of batteries in the same batch, performing a charge-discharge test by changing test conditions of each group of batteries until the battery capacity is attenuated to 80% of rated capacity, wherein the test conditions comprise ambient temperature, charge-discharge multiplying power and pretightening force, monitoring and recording the expansion force values, cycle times and battery capacities corresponding to the cycle times in the cycle charge-discharge process of the plurality of groups of batteries, drawing a battery capacity-cycle times curve, an expansion force-cycle times curve and an expansion force-battery capacity curve of each group of batteries, and analyzing;
the number of the battery packs is at least six, the first battery pack and the second battery pack are different in only ambient temperature, the third battery pack and the fourth battery pack are different in only ambient temperature, the first battery pack and the third battery pack are different in only charge and discharge multiplying power, the second battery pack and the fourth battery pack are different in only charge and discharge multiplying power, and the first battery pack, the fifth battery pack and the sixth battery pack are different in only initial pretightening force.
2. The battery swelling force influence factor testing and analyzing method according to claim 1, wherein: the test conditions for the first set of cells were: the charge-discharge multiplying power is 1C, the initial pretightening force is 300kg, and the ambient temperature is 25+/-2 ℃;
the test conditions for the second set of cells were: the charge-discharge multiplying power is 1C, the initial pretightening force is 300kg, and the ambient temperature is 45+/-2 ℃;
the test conditions for the third set of cells were: the charge-discharge multiplying power is 1/3C, the initial pretightening force is 300kg, and the ambient temperature is 25+/-2 ℃;
the test conditions for the fourth set of cells were: the charge-discharge multiplying power is 1/3C, the initial pretightening force is 300kg, and the ambient temperature is 45+/-2 ℃;
the test conditions for the fifth set of cells were: the charge-discharge multiplying power is 1C, the initial pretightening force is 400kg, and the ambient temperature is 25+/-2 ℃;
the test conditions for the sixth set of cells were: the charge-discharge multiplying power is 1C, the initial pretightening force is 200kg, and the ambient temperature is 25+/-2 ℃;
the rest time of the six groups of cells was the same.
3. The battery swelling force influence factor testing and analyzing method according to claim 1 or 2, wherein: according to the battery capacity-cycle number curves of the first group of batteries and the second group of batteries, comparing the capacities of the two groups of batteries under the same cycle number, and analyzing the influence of the environmental temperature on the service life of the batteries; according to the expansion force-cycle number curve and the expansion force-battery capacity curve of the first battery and the second battery, comparing the expansion force of the two batteries under the same cycle number, comparing the expansion force of the two batteries under the same battery capacity, and analyzing the influence of the environmental temperature on the irreversible deformation of the batteries.
4. The battery swelling force influence factor testing and analyzing method according to claim 1 or 2, wherein: according to the battery capacity-cycle number curves of the first group of batteries and the third group of batteries, comparing the capacity of the two groups of batteries under the same cycle number, analyzing the influence of charge-discharge multiplying power on the service life of the batteries, according to the expansion force-cycle number curves of the first group of batteries and the third group of batteries and the expansion force-battery capacity curves, comparing the expansion force of the two groups of batteries under the same cycle number, comparing the expansion force of the two groups of batteries under the same battery capacity, and analyzing the influence of charge-discharge multiplying power on the irreversible deformation of the batteries;
according to the battery capacity-cycle number curves of the second battery and the fourth battery, comparing the capacity of the two batteries under the same cycle number, analyzing the influence of the charge-discharge multiplying power on the service life of the battery, according to the expansion force-cycle number curves of the second battery and the fourth battery and the expansion force-battery capacity curves, comparing the expansion force of the two batteries under the same cycle number, comparing the expansion force of the two batteries under the same battery capacity, and analyzing the influence of the charge-discharge multiplying power on the irreversible deformation of the battery.
5. The battery swelling force influence factor testing and analyzing method according to claim 1 or 2, wherein: comparing the difference value of the capacities of the first group battery and the third group battery under the same cycle times with the difference value of the capacities of the second group battery and the fourth group battery under the same cycle times according to the battery capacity-cycle times curves of the first group battery and the third group battery and the second group battery and the fourth group battery, and analyzing the influence of the change of the charge-discharge multiplying power of the battery under different environment temperatures on the service life of the battery;
according to the expansion force-cycle number curve and the expansion force-battery capacity curve of the first battery and the third battery and the second battery and the fourth battery, comparing the difference value of the expansion forces of the first battery and the third battery under the same cycle number with the difference value of the expansion forces of the second battery and the fourth battery under the same cycle number, comparing the difference value of the expansion forces of the first battery and the third battery under the same battery capacity with the difference value of the expansion forces of the second battery and the fourth battery under the same battery capacity, and analyzing the influence of changing charge and discharge multiplying power on the expansion forces of the batteries under different environment temperatures.
6. The battery swelling force influence factor testing and analyzing method according to claim 1 or 2, wherein: and comparing the sizes of the battery capacities of the first group, the fifth group and the sixth group of batteries under the same cycle times according to the battery capacity-cycle times curves of the first group, the fifth group and the sixth group of batteries, and analyzing the influence of different pretightening forces on the service life of the batteries.
7. The battery swelling force influence factor testing and analyzing method according to claim 1 or 2, wherein: and drawing corresponding expansion force-SOC curves of each group of batteries in different SOHs, comparing the expansion force of the batteries in the group in different SOHs, and analyzing the change condition of reversible deformation of the batteries in the group in different SOHs.
8. The battery swelling force influence factor testing and analyzing method according to claim 7, wherein: comparing the change condition of battery expansion force in one charge and discharge process of the first battery and the second battery in each SOH, analyzing the size of the influence of the battery on the reversible deformation of the battery due to the environmental temperature in different SOHs, comparing the change condition of battery expansion force in one charge and discharge process of the first battery and the third battery in each SOH, analyzing the size of the influence of the charge and discharge multiplying power of the battery on the reversible deformation of the battery in different SOHs, comparing the change condition of battery expansion force in one charge and discharge process of the first battery, the fifth battery and the sixth battery in each SOH, and analyzing the size of the influence of the pretightening force of the battery on the reversible deformation of the battery in different SOHs.
9. The battery swelling force influence factor testing and analyzing method according to claim 7, wherein: according to the expansion force-SOC curve of each group of batteries, calculating the difference between the maximum value and the minimum value of the expansion force of each group of batteries in a charging and discharging process of each group of batteries in different SOHs, and analyzing the most sensitive factor of reversible deformation of the batteries in different SOHs.
10. The battery swelling force influence factor testing and analyzing method according to claim 1 or 2, wherein: and the method also comprises the step of performing charge and discharge tests by using batteries with different anode and cathode materials.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116577679A (en) * | 2023-07-12 | 2023-08-11 | 苏州精控能源科技有限公司 | Thermal runaway early warning method and system for large energy storage battery, electronic equipment and medium |
| CN116660760A (en) * | 2023-07-31 | 2023-08-29 | 宁德时代新能源科技股份有限公司 | Method, device, power consumption device and storage medium for determining SOH value of battery |
| CN116914277A (en) * | 2023-09-12 | 2023-10-20 | 厦门海辰储能科技股份有限公司 | Battery monomer, battery pack and power utilization device thereof |
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- 2023-03-30 CN CN202310324661.9A patent/CN116338477A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116577679A (en) * | 2023-07-12 | 2023-08-11 | 苏州精控能源科技有限公司 | Thermal runaway early warning method and system for large energy storage battery, electronic equipment and medium |
| CN116577679B (en) * | 2023-07-12 | 2023-09-12 | 苏州精控能源科技有限公司 | Thermal runaway early warning method and system for large energy storage battery, electronic equipment and medium |
| CN116660760A (en) * | 2023-07-31 | 2023-08-29 | 宁德时代新能源科技股份有限公司 | Method, device, power consumption device and storage medium for determining SOH value of battery |
| CN116660760B (en) * | 2023-07-31 | 2023-12-22 | 宁德时代新能源科技股份有限公司 | Method, device, power consumption device and storage medium for determining SOH value of battery |
| CN116914277A (en) * | 2023-09-12 | 2023-10-20 | 厦门海辰储能科技股份有限公司 | Battery monomer, battery pack and power utilization device thereof |
| CN116914277B (en) * | 2023-09-12 | 2024-01-26 | 厦门海辰储能科技股份有限公司 | Battery monomer, battery pack and power utilization device thereof |
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