CN112924880A - Method for measuring internal pressure and gas generation amount of battery after aging and application thereof - Google Patents

Method for measuring internal pressure and gas generation amount of battery after aging and application thereof Download PDF

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CN112924880A
CN112924880A CN202110100955.4A CN202110100955A CN112924880A CN 112924880 A CN112924880 A CN 112924880A CN 202110100955 A CN202110100955 A CN 202110100955A CN 112924880 A CN112924880 A CN 112924880A
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gas
aging
battery
gass
amount
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CN112924880B (en
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林春景
刘磊
王芳
温浩然
马天翼
刘仕强
樊彬
王金伟
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China Automotive Technology and Research Center Co Ltd
CATARC Automotive Test Center Tianjin Co Ltd
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China Automotive Technology and Research Center Co Ltd
CATARC Automotive Test Center Tianjin Co Ltd
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/389Measuring internal impedance, internal conductance or related variables
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/392Determining battery ageing or deterioration, e.g. state of health
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/396Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery

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Abstract

The invention relates to a method for testing the internal pressure and the amount of gas-generating substances after battery aging and application thereof. The test method comprises the following steps: testing the amount of internal gas substances of the standard sample piece when the standard sample piece is not aged by adopting a gas extraction method, wherein the gas extraction method is a method for extracting gas in the battery to test the amount of the internal gas substances of the battery; and respectively testing the volume of the battery when the standard sample piece is not aged, the aged volume of the sample piece to be tested and the expansion force of the sample piece to be tested at least two temperatures, and calculating the amount and the internal pressure of a gas generating substance after the sample piece to be tested is aged according to the amount of an internal gas substance when the standard sample piece is not aged, the volume of the battery when the standard sample piece is not aged, the aged volume of the sample piece to be tested and the expansion force of the sample piece to be tested at different temperatures. The method can realize the rapid, simple and accurate test of the amount and the internal pressure of the gas production substance in the battery in any aging state, and obtain the amount and the internal pressure of the gas production substance in the battery in the whole life cycle.

Description

Method for measuring internal pressure and gas generation amount of battery after aging and application thereof
Technical Field
The invention relates to the field of power battery detection, in particular to a method for testing the internal pressure and the amount of gas-generating substances after battery aging and application thereof.
Background
Due to the shortage of energy and the influence of greenhouse effect, the electric automobile has been developed in the past decade. In China, the electric automobile industry receives high attention of the government, and the government brings a series of scientific researches, demonstration applications and financial subsidy policies to support the development of electric automobiles. At present, lithium ion batteries are used as main or only power sources for hybrid electric vehicles and pure electric vehicles, which are mainstream at home and abroad, and the reason is that the lithium ion batteries have stronger competitive advantages in energy/power density, safety, cycle life, self-discharge rate and other aspects than other types of secondary batteries.
However, lithium ion batteries undergo various types of side reactions during cycling, accompanied by the generation of gases, which is particularly significant for high specific energy ternary system batteries. The gas generated inside the battery can lead to the increase of the distance between the pole piece and the diaphragm inside the battery, and the increase of ion transmission resistance, and further lead to the reduction of available capacity, energy and power characteristics. On the other hand, when the generated gas reaches a certain level, a protection mechanism inside the battery is triggered, thereby causing the battery to fail. Therefore, the accurate measurement of the amount and pressure of the gas generating substances in the battery under different aging states has important significance for improving the cycle performance and the safety performance of the battery.
At present, no effective method exists for the combined test of the internal gas pressure of the battery and the amount of gas generating substances, and particularly, the technical difficulty exists in testing the parameters of the batteries with different aging states. At present, most of tests are tests of the gas production volume in the battery, and the traditional method is mainly a drainage method. The drainage method is divided into two types, wherein one type belongs to a nondestructive testing method, namely, the battery is placed in distilled water which is not easy to conduct electricity, and the gas production volume of the battery is equivalently calculated according to the volume of the distilled water discharged by the battery. Another method belongs to a destructive test method, namely, a battery shell (generally an aluminum shell or a steel shell) or an aluminum plastic film package is perforated, gas in the battery is led out and is connected with a U-shaped pipe, and the method has the advantage that the pressure and the volume of the gas in the battery can be measured simultaneously. But it also has obvious disadvantages, firstly, the gas in the battery has components which are easy to react with water, thus leading to larger error of the test result; secondly, punching can destroy battery case structure, causes irreversible damage to the battery, influences follow-up other tests. Therefore, it has become necessary to develop a method capable of accurately measuring the amount and internal pressure of gas-generating substances inside a square hard-shell battery. Meanwhile, if the method can conveniently realize the test of the amount and the internal pressure of the gas production substances in the batteries with different aging states, the research and development efficiency of enterprises can be effectively improved, and the method has stronger engineering significance and value.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a method for testing the internal pressure and the gas generation amount of a battery after aging and application thereof, so as to realize the effect of accurately, simply and efficiently testing the gas generation amount and the internal pressure of the battery after aging.
In order to achieve the above purpose of the present invention, the following technical solutions are adopted:
in a first aspect, the present invention provides a method for measuring the amount of internal pressure and gassing substances after aging of a battery, comprising the steps of:
method for testing internal gas of standard sample piece without aging by adopting gas extraction methodAmount of substance ngass-1The gas drawing method is a method of drawing out gas inside a battery to test the amount of gas substances inside the battery;
respectively testing the volume V of the battery when the standard sample piece is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at least two temperatures after aging according to the amount n of the internal gas substances of the standard sample piece when the standard sample piece is not agedgass-1Battery volume V when standard sample is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging, and calculating the amount n of the gas-generating substance after aginggass-2And internal pressure Pgass-2
As a further preferable technical solution, the at least two temperatures include a temperature when the amount of the internal gas substance is not aged in the test standard sample, and a difference between the temperature when the amount of the internal gas substance is not aged in the test standard sample and a temperature when the volume of the battery is not aged in the test standard sample and a difference between temperatures when the volume of the sample to be tested is aged in the test standard sample are within a preset range.
As a further preferable technical scheme, the method for testing the amount n of the internal gas substances of the standard sample piece in the non-aging state by adopting the gas extraction methodgass-1The method comprises the following steps:
respectively testing the internal pressure P of the standard sample piece when the standard sample piece is not aged by adopting a gas extraction methodgass-1And an internal gas volume Vgass-1Calculating the amount n of the internal gas substance when the standard sample is not agedgass-1,Vgass-1And Pgass-1Are all at a first temperature T1The process is carried out as follows.
As a further preferred solution, the amount n of the internal gas substance in the unaged standard samplegass-1The following formula is used for calculation:
Figure BDA0002915625470000031
wherein R is the gas constant.
As a further preferred technical scheme, the battery volume V is measured when the standard sample is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging according to the amount n of the internal gas substances of the standard sample piece when the standard sample piece is not agedgass-1Battery volume V when standard sample is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging, and calculating the amount n of the gas-generating substance after aginggass-2And internal pressure Pgass-2The method comprises the following steps:
respectively testing the volume V of the battery when the standard sample piece is not agedcell-1And the volume V of the sample to be measured after agingcell-2Calculating the gas production volume V of the sample to be measured after aginggass-2,Vcell-1And Vcell-2Are all at a first temperature T1Measuring;
respectively testing the expansion force F of the sample piece to be tested at the first temperature after aging1And expansion force F at a second temperature2(ii) a The second temperature is denoted as T2
According to the expansion force F at the first temperature1Expansion force at second temperature F2The contact area S between the pressure sensor and the clamp during the expansion force test, and the amount n of the internal gas substance when the standard sample piece is not agedgass-1Internal gas volume V when standard sample is not agedgass-1And the gas production volume V of the sample piece to be measured after aginggass-2Calculating the amount n of gas generated after the sample piece to be tested is agedgass-2
According to the amount n of internal gaseous substances when the standard sample is not agedgass-1The amount n of the gas-generating substance after the sample member to be measured is agedgass-2Internal gas volume V when standard sample is not agedgass-1Gas production volume V after aging of sample piece to be testedgass-2And a first temperature T1Calculating the internal pressure P of the sample to be measured after aginggass-2
As a further preferred technical scheme, the gas production volume V of the sample piece to be detected after aginggass-2The following formula is used for calculation: vgass-2=Vcell-2-Vcell-1
As a further preferred technical scheme, the amount n of the gas production substance of the sample piece to be detected after aginggass-2The following formula is used for calculation:
Figure BDA0002915625470000041
wherein R is the gas constant.
As a further preferable technical scheme, the internal pressure P of the sample piece to be measured after aginggass-2The following formula is used for calculation:
Figure BDA0002915625470000042
wherein R is the gas constant.
As a further preferred solution, the temperature difference between the at least two temperatures is higher than 20 ℃.
In a second aspect, the invention provides an application of the method for testing the internal pressure and the amount of gas generated after the battery is aged in analyzing the aging characteristics of the battery, determining the threshold value for starting the uncontrolled pressure relief of the battery or regulating the aging behavior of the battery.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a method for testing the amount of internal pressure and gas-generating substances after aging of a battery, which comprises the steps of firstly testing the amount n of internal gas substances when a standard sample is not aged by adopting a gas extraction methodgass-1In n isgass-1As a reference, the amount of the internal gas substance in the unaged other sample to be measured was determined. Because the gas extraction method needs to extract the gas in the battery, for example, the battery shell is perforated and then the internal gas is extracted, the method has irreversible damage to the battery, and other tests on the battery can not be carried out after the internal gas is obtained, therefore, the invention replaces the amount of the internal gas substances of all other samples to be tested when the samples to be tested are not aged by testing the amount of the internal gas substances of the standard sample, does not need to modify the samples to be tested, and avoids the damage of the samples to be tested.
Then, the volume V of the battery is measured by respectively testing the unaged standard samplecell-1Volume V of sample piece to be measured after agingcell-2And the sample to be tested expands at different temperatures after agingForce according to the amount n of internal gaseous substances when the standard sample is not agedgass-1Battery volume V when standard sample is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging, and the amount n of the gas production substance after aging of the sample piece to be tested is calculatedgass-2And internal pressure Pgass-2. It can be seen that when a sample to be tested is tested, the main test items are the aged volume and the expansion force at different temperatures of the sample to be tested, and the volume of the battery when the standard sample is not aged, and the amount and the internal pressure of the gas production substance of the sample to be tested after aging can be calculated according to the data. Meanwhile, because the sample piece to be tested does not need to be modified, particularly a destructive testing mode is not adopted, the error caused by the reaction of the generated gas and water can be avoided, and the testing result is more accurate.
According to the method, the quantity and the internal pressure of the gas generating substance in the battery in any aging state can be quickly, simply and accurately tested only through the standard sample without destructively modifying the sample to be tested in other aging states, and the quantity and the internal pressure of the gas generating substance in the battery in any aging state can be obtained by means of measuring the expansion force of the gas in the battery caused by the temperature change.
After the method is adopted for testing, on one hand, data support can be provided for analyzing the aging characteristics of the battery and determining the thermal runaway pressure release starting threshold of the battery, the research and development period is shortened, and the research and development efficiency of enterprises is improved; on the other hand, by rapidly measuring the gas production behavior of the battery cell in the aging process, the influence of different design and use factors on the gas production behavior of the battery can be evaluated, and the method is used for regulating and controlling the aging behavior of the battery cell to improve the performance of the battery cell.
Drawings
FIG. 1 is a flow chart of a method for testing the amount of internal pressure and gassing substances after aging of a battery according to the present invention;
FIG. 2 is a schematic diagram of internal pressure of a test standard sample without aging;
FIG. 3 is a schematic illustration of the internal gas volume of a test standard when unaged;
FIG. 4 is a schematic illustration of an expansion force test;
FIG. 5 is a schematic diagram showing the relationship between the expansion force increase and the temperature rise after 1200 cycles of a lithium iron phosphate lithium ion battery;
fig. 6 is a schematic diagram of the corresponding relationship between the expansion force increase value and the temperature rise amplitude of a certain lithium iron phosphate lithium ion battery under different aging states.
Icon: 1-standard sample piece; 2-metal piping; 3-a valve; 4-a pressure gauge; 5-U-shaped pipe; 6-a suction device; 7-a clamp; 8-a sample to be tested; 9-pressure sensor.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer.
According to an aspect of the present invention, as shown in fig. 1, the present embodiment provides a method for testing the internal pressure and the amount of gas-generating substances after aging of a battery, which is suitable for testing the internal pressure and the amount of gas-generating substances after aging of a prismatic battery (e.g., a prismatic hard-shell battery), a cylindrical battery, and a pouch battery, for example, a lithium ion battery.
The term "aging" means that the battery is cycled several times at a certain temperature, for example, 45 ℃ or 55 ℃, at a certain charge/discharge rate, for example, 1C, at a discharge rate, for example, 2C, and at a cycle number, for example, 300 to 1000, and the cycle number is also considered in the battery system, for example, the cycle life of the lithium iron phosphate/graphite system battery is longer, and a larger cycle number is recommended, and the cycle number of the ternary/graphite system battery is recommended to be smaller.
The "internal pressure" refers to the pressure generated by all internal gases (including the internal original gases and the gases newly generated after aging) after aging of the battery.
The "amount of gas-generating substance" refers to the amount of gas-generating substance newly generated after the battery is aged.
Referring to fig. 1, the test method includes the steps of:
s110, testing the amount n of internal gas substances of the standard sample piece in the non-aging state by adopting a gas extraction methodgass-1The gas drawing method is a method of drawing out gas inside a battery to test the amount of gas substances inside the battery.
The "standard" refers to a battery of a certain size and having an electrochemical performance that reaches the median level of the battery of the certain size. The cells at the median level refer to cells at the median position in the sequence ordered by electrochemical performance goodness.
The "amount of substance" is also referred to as a molar number and indicates a group containing a certain number of particles, and the unit is a mole and the unit symbol is a mole.
The "gas extraction method" can be carried out in vacuum or air, and the process is carried out on the premise that the battery shell does not deform obviously. Because the gas in the battery is mainly air when the battery is not aged and gas which is easy to react with water does not exist, the influence on the test error is effectively avoided.
Preferably, the method for testing the amount n of the internal gas substances of the standard sample piece in the non-aged state by adopting the gas extraction methodgass-1The method comprises the following steps:
respectively testing the internal pressure P of the standard sample piece when the standard sample piece is not aged by adopting a gas extraction methodgass-1And an internal gas volume Vgass-1Calculating the amount n of the internal gas substance when the standard sample is not agedgass-1,Vgass-1And Pgass-1Are all at a first temperature T1The process is carried out as follows.
The internal pressure of the standard sample piece can be tested by adopting the schematic diagram shown in fig. 2 when the internal pressure is not aged, a hole is formed above the standard sample piece 1 (usually, one side of the pressure release valve) and is in sealing connection with the metal pipeline 2, then the metal pipeline 2 is connected with the pressure gauge 4, the valve 3 is arranged between the metal pipeline 2 and the pressure gauge 4, and the degree of the pressure gauge is the internal pressure of the standard sample piece when the standard sample piece is not aged.
The method can be carried out by adopting the schematic diagram shown in fig. 3 when the internal gas volume of the standard sample piece is not aged, punching is carried out above the standard sample piece 1 (generally, one side of a pressure release valve) and is in sealing connection with a metal pipeline 2, the standard sample piece 1 is further connected with a U-shaped pipe 5 through the metal pipeline 2, a valve 3 is arranged between the metal pipeline 2 and the U-shaped pipe 5, water is filled in the U-shaped pipe 5, scales are arranged on the surface of the U-shaped pipe 5, the other end of the U-shaped pipe 5 is connected with a suction device 6, and the suction device is a vacuum pump or an.
Further, the amount n of the internal gas substance when the master piece is not agedgass-1The following formula is used for calculation:
Figure BDA0002915625470000081
wherein R is the gas constant.
S120, respectively testing the volume V of the battery when the standard sample piece is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at least two temperatures after aging according to the amount n of the internal gas substances of the standard sample piece when the standard sample piece is not agedgass-1Battery volume V when standard sample is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging, and calculating the amount n of the gas-generating substance after aginggass-2And internal pressure Pgass-2
It should be understood that the standard sample and the sample to be tested should be batteries of the same model and the same batch, so that the parameters of the standard sample before aging can be used to replace the parameters of the sample before aging, and the batteries of different batches of the same model or different models have certain errors, and the standard sample is not representative.
The "sample to be tested" refers to a battery of the same type and batch as the standard sample and to be tested for the amount of internal pressure and gas generation substances after aging.
The above-mentioned "at least two temperatures" includes two temperatures, three temperatures, four temperatures, or the like. Generally, the amount of the desired substance can be measured at two temperatures, and in order to improve the accuracy of the measurement, one or more additional measurement temperatures may be added, and then the average value of the amounts of the plurality of substances to be measured is used as the amount of the desired substance.
The "swelling force" refers to the pressure on the side of the battery.
Preferably, the at least two temperatures include a temperature when the amount of the internal gas substance of the standard sample is not aged, and a difference between the temperature when the amount of the internal gas substance of the standard sample is not aged and a temperature when the volume of the battery is not aged and a difference between temperatures when the volume of the sample to be tested is aged are within a preset range. When the above conditions are satisfied, it can be considered that the amount of the internal gas substance has a more accurate substitution effect on the sample to be measured when the standard sample is not aged. More preferably, the difference between the temperatures is 0.
Preferably, the temperature difference of the at least two temperatures is higher than 20 ℃. The temperature differences are all higher than 20 ℃ in the sense that the temperature difference between each two temperatures is higher than 20 ℃, for example, when two temperatures are tested, the temperature difference between the two temperatures is higher than 20 ℃, when three temperatures are tested, the temperature difference between every two of the three temperatures is higher than 20 ℃, and so on. The temperature difference is too small, the change of the expansion force is less obvious, the generated error is larger, and the accuracy of the test is not facilitated.
Preferably, the separate test standard sample has a battery volume V when not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging according to the amount n of the internal gas substances of the standard sample piece when the standard sample piece is not agedgass-1Battery volume V when standard sample is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging, and calculating the amount n of the gas-generating substance after aginggass-2And internal pressure Pgass-2The method comprises the following steps:
s121, respectively testing the volume V of the battery when the standard sample piece is not agedcell-1And the volume V of the sample to be measured after agingcell-2Calculating the gas production volume V of the sample to be measured after aginggass-2,Vcell-1And Vcell-2Are all at a first temperature T1And (4) measuring.
The volume Vcell-1And volume Vcell-2All adopt drainage method to measure, will correspond to the battery and place in distilled water, test and obtain the required volume. Gas production volume V of sample to be tested after aginggass-2The following formula is used for calculation: vgass-2=Vcell-2-Vcell-1
S122, respectively testing the expansion force F of the sample piece to be tested at the first temperature after aging1And expansion force F at a second temperature2(ii) a The second temperature is denoted as T2
The expansion force at each temperature can be tested by adopting the schematic diagram shown in fig. 4, the sample 8 to be tested is clamped by adopting the clamp 7, and the clamp 7 is also provided with the pressure sensor 9. When the expansion force is tested, the battery is not charged and discharged, and the temperature change can cause weak electron transfer in the battery because the battery is not charged and discharged, but the influence on the expansion force of the battery is extremely small and can be ignored. Therefore, the difference in expansion force at each temperature is mainly caused by the pressure change of the battery internal gas caused by the temperature change. Therefore, the change Δ P in the internal pressure of the sample to be measured is: Δ P ═ Δ F/S ═ (F)2-F1)/S。
Setting the initial value of the expansion force to be 1000N, placing the expansion force device and the sample piece to be tested in a temperature box, standing for 2 hours, and judging that the surface temperature change rate of the battery to be tested is less than 1 ℃/min when the temperature of the battery is consistent with the temperature in the temperature box.
S123, expansion force F according to first temperature1Expansion force at second temperature F2The contact area S between the pressure sensor and the clamp during the expansion force test, and the amount n of the internal gas substance when the standard sample piece is not agedgass-1Internal gas volume V when standard sample is not agedgass-1And treatGas production volume V after sample aginggass-2Calculating the amount n of gas generated after the sample piece to be tested is agedgass-2
From the ideal gas equation, Δ P × V ═ n × R × Δ T, Δ T ═ T2-T1,n=ngass-1+ngass-2,V=Vgass-1+Vgass-2
As can be further derived, the following results show that,
Figure BDA0002915625470000101
wherein R is the gas constant.
S124, according to the amount n of the internal gas substances when the standard sample piece is not agedgass-1The amount n of the gas-generating substance after the sample member to be measured is agedgass-2Internal gas volume V when standard sample is not agedgass-1Gas production volume V after aging of sample piece to be testedgass-2And a first temperature T1Calculating the internal pressure P of the sample to be measured after aginggass-2
Specifically, according to the ideal state gas equation, the internal pressure P of the sample to be measured after aging is knowngass-2Comprises the following steps:
Figure BDA0002915625470000102
wherein R is the gas constant.
The method is adopted to test the internal pressure and the gas generation amount of a certain lithium iron phosphate lithium ion battery after the battery is aged, and a sample piece to be tested is subjected to a cycle life test (namely aging) for a certain number of times at the temperature of 45 ℃, wherein the cycle life test comprises 1C constant current charging and 2C constant current discharging which are respectively cycled to 1200 circles and 1500 circles.
And (3) placing the sample piece to be tested which circulates to 1200 circles in an expansion force testing device, placing the expansion force testing device and the sample piece to be tested in a temperature box together, adjusting the temperature in the temperature box from a value of 25 ℃ to a value of 55 ℃, 60 ℃, 65 ℃, 70 ℃ and 75 ℃ respectively, and recording expansion force increase values under different temperature rise amplitudes (the result is shown in figure 5).
As can be seen from the test data shown in fig. 5, for the battery in the aged state of 90%, the expansion force of the battery and the temperature rise amplitude show strict equal ratio relationship at different temperature rise amplitudes (30 ℃ or higher), and the proportionality coefficient for the sample is 1.2. This phenomenon is mainly caused by the fact that the change in the internal gas pressure of the battery during this process is caused by thermal expansion due to the temperature rise, and there is an equal ratio relationship between the internal gas pressure of the battery and the amount of the internal gas substance of the battery, and therefore there is a correspondence relationship between the amount of the internal gas substance of the battery and the expansion force of the battery.
The sample pieces to be tested which circulate to 1200 circles and 1500 circles are placed in an expansion force testing device, the expansion force testing device and the sample pieces to be tested are placed in a temperature box together, the temperature in the temperature box is adjusted from a value of 25 ℃ to 50 ℃ and from the value of 25 ℃ to 55 ℃, and the expansion force increasing values in the different processes are recorded (the result is shown in figure 6).
Based on the analysis, the relationship of the expansion force increase of the samples in different aging states under the same temperature rise amplitude is further analyzed. From the test data shown in fig. 6, it can be seen that the expansion force changes of the batteries under different aging states under the same temperature rise condition also show an obvious proportional relationship, and for the batteries, the proportional coefficient is 2.1, so that the rationality of the method of the present invention is verified.
According to another aspect of the invention, the invention further provides application of the method for testing the internal pressure and the gas generation amount of the aged battery in analysis of battery aging characteristics, determination of an uncontrolled pressure release starting threshold value of the battery or regulation and control of battery aging behaviors. The test method is applied to analyzing the aging characteristics of the battery, determining the uncontrolled pressure relief starting threshold value of the battery or regulating the aging behavior of the battery, and is beneficial to accurately analyzing the aging characteristics of the battery, accurately determining the uncontrolled pressure relief starting threshold value of the battery and effectively regulating the aging behavior of the battery.
While particular embodiments of the present invention have been illustrated and described, it would be obvious that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims (10)

1. A method for testing the internal pressure and the amount of gas-generating substances after the battery is aged, which is characterized by comprising the following steps:
testing the amount n of internal gas substances of a standard sample piece in the absence of aging by a gas extraction methodgass-1The gas drawing method is a method of drawing out gas inside a battery to test the amount of gas substances inside the battery;
respectively testing the volume V of the battery when the standard sample piece is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at least two temperatures after aging according to the amount n of the internal gas substances of the standard sample piece when the standard sample piece is not agedgass-1Battery volume V when standard sample is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging, and calculating the amount n of the gas-generating substance after aginggass-2And internal pressure Pgass-2
2. The method according to claim 1, wherein the at least two temperatures include a temperature at which the amount of the internal gas substance is measured when the standard sample is not aged, and a difference between the temperature at which the amount of the internal gas substance is measured when the standard sample is not aged and a temperature at which the volume of the battery is measured when the standard sample is not aged and a difference between the temperatures at which the volume of the sample to be measured is measured after aging are within predetermined ranges.
3. The method for measuring the amount of internal pressure and outgassed substances after aging of a battery according to claim 1, wherein the amount n of internal gas substances in the unaged standard sample is measured by a gas extraction methodgass-1The method comprises the following steps:
respectively testing the internal pressure P of the standard sample piece when the standard sample piece is not aged by adopting a gas extraction methodgass-1And an internal gas volume Vgass-1Calculating the amount n of the internal gas substance when the standard sample is not agedgass-1,Vgass-1And Pgass-1Are all at a first temperature T1The process is carried out as follows.
4. The method for measuring the amount of internal pressure and outgassed substances after aging of a battery as claimed in claim 3, wherein the amount of internal gas substances n in the unaged standard sample is measuredgass-1The following formula is used for calculation:
Figure FDA0002915625460000011
wherein R is the gas constant.
5. The method for measuring the amount of internal pressure and gas generation substances after aging of a battery according to claim 3, wherein the volume V of the battery before aging of the standard sample is measured separatelycell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging according to the amount n of the internal gas substances of the standard sample piece when the standard sample piece is not agedgass-1Battery volume V when standard sample is not agedcell-1Volume V of sample piece to be measured after agingcell-2And the expansion force of the sample piece to be tested at different temperatures after aging, and calculating the amount n of the gas-generating substance after aginggass-2And internal pressure Pgass-2The method comprises the following steps:
respectively testing the volume V of the battery when the standard sample piece is not agedcell-1And the volume V of the sample to be measured after agingcell-2Calculating the gas production volume V of the sample to be measured after aginggass-2,Vcell-1And Vcell-2Are all at a first temperature T1Measuring;
respectively testing the expansion force F of the sample piece to be tested at the first temperature after aging1And expansion force F at a second temperature2(ii) a The second temperature is denoted as T2
According to the expansion force F at the first temperature1Expansion force at second temperature F2The contact area S between the pressure sensor and the clamp during the expansion force test, and the amount n of the internal gas substance when the standard sample piece is not agedgass-1Internal gas volume V when standard sample is not agedgass-1And the product of the sample piece to be tested after agingVolume of gas Vgass-2Calculating the amount n of gas generated after the sample piece to be tested is agedgass-2
According to the amount n of internal gaseous substances when the standard sample is not agedgass-1The amount n of the gas-generating substance after the sample member to be measured is agedgass-2Internal gas volume V when standard sample is not agedgass-1Gas production volume V after aging of sample piece to be testedgass-2And a first temperature T1Calculating the internal pressure P of the sample to be measured after aginggass-2
6. The method of claim 5, wherein the volume V of the gas generated from the sample after aging is measuredgass-2The following formula is used for calculation: vgass-2=Vcell-2-Vcell-1
7. The method of claim 5, wherein the amount of gas generating substance n is determined by measuring the amount of gas generating substance in the sample after aginggass-2The following formula is used for calculation:
Figure FDA0002915625460000021
wherein R is the gas constant.
8. The method according to claim 5, wherein the internal pressure P of the sample to be measured after aging is measuredgass-2The following formula is used for calculation:
Figure FDA0002915625460000031
wherein R is the gas constant.
9. The method for testing the internal pressure and the amount of a substance generating gas after aging of a battery according to any one of claims 1 to 8, wherein the temperature difference of the at least two temperatures is higher than 20 ℃.
10. Use of a method for testing the internal pressure and the amount of gas-generating substances after battery aging according to any of claims 1 to 9 for analyzing the aging characteristics of a battery, for determining the runaway pressure relief opening threshold of a battery or for regulating the aging behavior of a battery.
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