CN108446435B - Power battery electrode material thermal stability judgment method and device and computer readable storage medium - Google Patents

Power battery electrode material thermal stability judgment method and device and computer readable storage medium Download PDF

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CN108446435B
CN108446435B CN201810123757.8A CN201810123757A CN108446435B CN 108446435 B CN108446435 B CN 108446435B CN 201810123757 A CN201810123757 A CN 201810123757A CN 108446435 B CN108446435 B CN 108446435B
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electrode material
power battery
power
thermal stability
reaction
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CN108446435A (en
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任东生
刘翔
冯旭宁
卢兰光
欧阳明高
李建秋
王烁祺
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Tsinghua University
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/08—Thermal analysis or thermal optimisation
    • 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 application discloses a method and a device for judging thermal stability of an electrode material of a power battery and a computer-readable storage medium. The method comprises the following steps: s10, selecting temperature data of the electrode material of the first power battery; s20, obtaining heat generation power data of the first power battery electrode material according to the temperature data of the first power battery electrode material and a thermal decomposition reaction kinetic model of the electrode material; and S30, comparing the heat generation power data with a standard value, and judging the thermal stability of the first power battery electrode material. The method can be used for evaluating the thermal stability of the first power battery electrode material at different temperatures, can be used for comprehensively evaluating the thermal stability of the first power battery electrode material, and can improve the evaluation efficiency of the thermal stability of the electrode material.

Description

Power battery electrode material thermal stability judgment method and device and computer readable storage medium
Technical Field
The present disclosure relates to the field of batteries, and in particular, to a method and an apparatus for determining thermal stability of an electrode material of a power battery, and a computer-readable storage medium.
Background
The traditional electric automobile is the main body of a new energy automobile, and the power battery is the core energy source of the electric automobile. The lithium ion power battery (hereinafter referred to as "power battery") has the advantages of high energy/power density and long service life, and is the most widely applied chemical power source for vehicles at present. Due to the limited vehicle-mounted space, in order to increase the driving range of the electric vehicle, the specific energy of the power battery is required to be increased besides the power battery which is additionally arranged in the limited vehicle-mounted space. In order to increase the specific energy of the battery, researchers have developed a variety of new material systems. However, these new material systems are required to meet a range of industrial standards, including safety standards, etc., when used in large-scale industrialized batteries. Because the energy released by thermal runaway of the power battery with higher specific energy is more concentrated when a safety accident occurs, the thermal runaway safety performance of the battery after large-scale mass production must be ensured in the design and development process of the power battery with high specific energy.
The safety of the power battery is mainly related to the thermal stability of the electrode material. In general, the thermal stability of the electrode material of the power battery can be evaluated by obtaining the heat generation rate of the thermal decomposition of the electrode material at a specific temperature through an accelerated calorimetric test or a differential scanning calorimetric test. However, the method for evaluating the thermal stability of the electrode material through the thermal test can only qualitatively evaluate the thermal stability of the electrode material under specific heating conditions, and the evaluation result is difficult to expand to other heating conditions, so that the thermal stability of the electrode material cannot be comprehensively evaluated.
Disclosure of Invention
In view of the above, it is necessary to provide a method, an apparatus and a computer-readable storage medium for determining thermal stability of an electrode material of a power battery, which can solve the problem that the conventional method for determining thermal stability of an electrode material of a power battery can only be used under specific conditions.
A method for judging the thermal stability of an electrode material of a power battery comprises the following steps:
s10, selecting temperature data of the electrode material of the first power battery;
s20, obtaining heat generation power data of the first power battery electrode material according to the temperature data of the first power battery electrode material and a thermal decomposition reaction kinetic model of the electrode material; and
and S30, comparing the heat generation power data with a standard value, and judging the thermal stability of the first power battery electrode material.
In one embodiment, in S20, the method for establishing the thermal decomposition reaction kinetic model includes:
s21, providing a second power battery, and carrying out battery charging and discharging processing on the second power battery;
s22, disassembling the second power battery after the charging and discharging treatment to obtain a second power battery electrode material;
s23, selecting a temperature rise rate value, and carrying out scanning calorimetry test on the second power battery electrode material according to the temperature rise rate value to obtain a temperature-power relation curve of test temperature data and test heat generation power data of the reaction of the second power battery electrode material; and
and S24, calculating the reaction kinetic parameter value of the electrode material of the second power battery according to the temperature-power relation curve, and obtaining the thermal decomposition reaction kinetic model according to the reaction kinetic parameter value.
In one embodiment, the S24 includes:
s241, obtaining peak temperature data of the temperature-power relation curve and a temperature rise rate value corresponding to the peak temperature data;
s242, establishing a reaction kinetic equation of the second power battery electrode material, and obtaining a heat generation power calculation formula of the second power battery electrode material according to a mass conservation equation, a heat release power calculation formula and the reaction kinetic equation;
s243, calculating the reaction kinetic parameter value according to the peak temperature data and the temperature rise rate value corresponding to the peak temperature data, a thermal analysis kinetic equation and the heat generation power calculation formula; and
and S244, obtaining the thermal decomposition reaction kinetic model according to the reaction kinetic equation, the heat generation power calculation formula and the reaction kinetic parameter value.
In one embodiment, in S242, the reaction kinetic equation is:
Figure GDA0003208112580000021
the mass conservation equation is as follows:
Figure GDA0003208112580000031
the heat release power calculation formula is as follows:
Figure GDA0003208112580000032
wherein x represents the reaction of the second power cell electrode material; c. CxA normalized concentration of a reactant representing a reaction of the second power cell electrode material in units of 1; a. thexRepresents the forward factor of the reaction in units of s-1；Ea,xRepresents the activation energy of the reaction and has the unit of J.mol-1(ii) a R is an ideal gas constant 8.314 J.mol-1·K-1，nxIs the reaction order, the unit is 1, and T is the temperature of the second electrode material; qxRepresenting the exothermic power of the reaction; m represents the mass of the reactants in g; hxRepresents the reaction enthalpy of the reaction x of the second electrode material in the reaction kinetic parameters and has the unit of J.g-1；Ax，Ea,x,nxAnd HxRepresents the reaction kinetic parameters.
In one embodiment, the heat generation power calculation is:
Q＝Qx_1+Qx_2+Qx_3+… (4)
wherein the subscripts x _1, x _2, x _3 … represent the reaction of the different second electrode materials.
In one embodiment, the thermoanalytical kinetic equation is:
Figure GDA0003208112580000033
wherein, betaiRepresenting said rate of rise value, Tpi,xRepresenting the peak temperature data.
In one embodiment, before the S241, the method further includes:
and S240, obtaining the number of exothermic reactions of the electrode material of the second power battery according to the temperature-power relation curve.
In one embodiment, in S243, the reaction kinetic parameter value is calculated by a numerical optimization method.
A power battery electrode material thermal stability judging device comprises a power battery electrode material thermal stability judging device and a computer, wherein the computer comprises a memory, a processor and a computer program which is stored on the memory and can run on the processor, and the processor adopts a power battery electrode material thermal stability judging method when executing the computer program, and the method comprises the following steps:
s10, selecting temperature data of the electrode material of the first power battery;
s20, obtaining heat generation power data of the first power battery electrode material according to the temperature data of the first power battery electrode material and a thermal decomposition reaction kinetic model of the electrode material; and
and S30, comparing the heat generation power data with a standard value, and judging the thermal stability of the first power battery electrode material.
A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, is operative to carry out the steps of the method.
According to the method for judging the thermal stability of the power battery electrode material, the temperature data of the first power battery electrode material is input into the thermal decomposition reaction kinetic model, and then the heat generation power data of the first power battery electrode material is obtained. And judging the thermal stability of the electrode material of the first power battery according to the heat generation power data. The method for judging the thermal stability of the electrode material of the power battery can be used for evaluating the thermal stability of the electrode material of the first power battery at different temperatures, comprehensively evaluating the thermal stability of the electrode material of the first power battery, and improving the evaluation efficiency of the thermal stability of the electrode material.
Drawings
Fig. 1 is a flowchart of a method for determining thermal stability of an electrode material of a power battery according to an embodiment of the present disclosure;
FIG. 2 is a temperature-power relationship graph of a scanning calorimetry test at a temperature-rise rate for a second power cell electrode material provided by an embodiment of the present application;
FIG. 3 is a temperature-power relationship graph of a scanning calorimetry test at a plurality of temperature-rise rates for a second power cell electrode material provided by an embodiment of the present application;
FIG. 4 shows the exothermic reaction of the second power cell electrode material provided in the examples of the present application
Figure GDA0003208112580000041
A relationship diagram of (1);
FIG. 5 is a graph comparing the predicted results and experimental results of the thermal decomposition reaction kinetics model in the examples of the present application;
fig. 6 is a schematic diagram of a device for determining thermal stability of a battery electrode material according to an embodiment of the present disclosure.
Detailed Description
In order to make the objects, technical solutions and technical effects of the present application more apparent, specific embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Referring to fig. 1, an embodiment of the present application provides a method for determining thermal stability of an electrode material of a power battery. The method for judging the thermal stability of the power battery electrode material comprises the following steps:
s10, selecting temperature data of the electrode material of the first power battery;
s20, obtaining heat generation power data of the first power battery electrode material according to the temperature data of the first power battery electrode material and a thermal decomposition reaction kinetic model of the electrode material; and
and S30, comparing the heat generation power data with a standard value, and judging the thermal stability of the first power battery electrode material.
In step S10, the temperature data of the first power battery electrode material may be a battery temperature when the thermal stability determination is performed on the first power battery electrode material. The first power battery can be a lithium battery, and can also be other types of batteries.
In step S20, the thermal stability of the first power battery electrode material at the battery temperature can be determined by the thermal decomposition reaction kinetic model. Inputting the battery temperature data into the thermal decomposition reaction kinetic model, the heat generation power data can be obtained. Through the size of the heat-generating power data, the thermal stability of the first power battery electrode material can be predicted. In one embodiment, a thermal decomposition reaction kinetic model of the electrode material of the lithium battery can be established. When testing the thermal stability of the electrode materials of the same type of lithium batteries, the temperature data can be directly input into the thermal decomposition reaction kinetic model, and the heat production power data of the electrode materials of the same type of lithium batteries can be obtained through calculation. It is understood that the thermal decomposition reaction kinetic model is established according to the physicochemical properties of the first power battery electrode material, and therefore, the thermal decomposition reaction kinetic model can be applied to the judgment of the thermal stability of the first power battery electrode material in the same way.
In step S30, the thermal stability of the first power battery electrode material can be judged according to the standard value. The standard value can be a critical value for judging the thermal stability of the first power battery electrode material. The threshold value may be a heat-producing power data value. The critical value may be obtained empirically. When the heat generation power data is smaller than the standard value, the first power battery electrode material can be judged to be in a stable state. When the heat generation power data is larger than the standard value, the first power battery electrode material can be judged to be in an unstable state.
In one embodiment, the standard value can be three sub-standard values of "high, medium, and low". The three sub-standard values of high, medium and low can be divided according to the magnitude of the heat production power data value. The heat production power data values corresponding to the three sub-standard values of high, medium and low can be reduced in sequence. The three sub-standard values may classify the thermal stability of the first power cell electrode material into 3 levels. When the heat generation power data of the first power battery electrode material is larger than the high substandard value, the first power battery electrode material is indicated to have the worst thermal stability. When the heat-generating power data of the first power cell electrode material is between the "high" sub-normalized value and the "medium" sub-normalized value, the first power cell electrode material is indicated to have poor thermal stability. When the heat generation power data of the first power battery electrode material is between the 'middle' sub-standard value and the 'low' sub-standard value, the first power battery electrode material is proved to have better thermal stability. When the heat generation power data of the first power battery electrode material is smaller than the low substandard value, the first power battery electrode material is proved to have good thermal stability.
According to the method for judging the thermal stability of the power battery electrode material, the temperature data of the first power battery electrode material is input into the thermal decomposition reaction kinetic model, and then the heat production power data of the first power battery electrode material is obtained. And judging the thermal stability of the electrode material of the first power battery according to the heat generation power data. The method for judging the thermal stability of the electrode material of the power battery can be used for evaluating the thermal stability of the electrode material of the first power battery at different temperatures, comprehensively evaluating the thermal stability of the electrode material of the first power battery, and improving the evaluation efficiency of the thermal stability of the electrode material.
In one embodiment, the method for establishing the thermal decomposition reaction kinetic model comprises the following steps:
s21, providing a second power battery, and carrying out battery charging and discharging processing on the second power battery;
s22, disassembling the second power battery after the charging and discharging treatment to obtain a second power battery electrode material;
s23, selecting a temperature rise rate value, and carrying out scanning calorimetry test on the second power battery electrode material according to the temperature rise rate value to obtain a temperature-power relation curve of test temperature data and test heat generation power data of the reaction of the second power battery electrode material; and
and S24, calculating the reaction kinetic parameter value of the electrode material of the second power battery according to the temperature-power relation curve, and obtaining the thermal decomposition reaction kinetic model according to the reaction kinetic parameter value.
In step S21, the second power cell is first manufactured, and the electrode material of the second power cell is determined. The physical and chemical properties of the second power battery electrode material are the same as those of the first power battery electrode material. It is understood that the thermal decomposition reaction kinetic model is established based on the second power cell electrode material. Since the physical and chemical properties of the materials of the second power battery and the first power battery are completely the same, the thermal stability of the electrode material of the first power battery can be judged by the thermal decomposition reaction kinetic model.
In one embodiment, the method can be used according to actual needsAnd selecting a conductive agent, a bonding agent and a current collector to manufacture the second power battery. The conductive agent may be acetylene black, and the binder may be polyvinylidene fluoride (PVDF). The current collector is determined according to the electrode material to be tested. The positive electrode material of the second power battery can select an aluminum foil as a current collector, and the negative electrode material of the second power battery can select a copper foil as a current collector. When the electrode plate is manufactured, the electrode active material, the conductive agent and the binder are mixed according to a set proportion, are uniformly mixed into paste, are uniformly coated on a current collector, and are finally compacted, cut and dried to obtain the electrode plate. In one embodiment, the second power cell electrode material is a ternary positive active material (Li)xNi1/3Co1/3Mn1/3O2) The conductive agent is acetylene black, the binder is polyvinylidene fluoride (PVDF), the current collector is aluminum foil, and the negative current collector is copper foil. The proportion of the anode of the electrode can be ternary anode active materials: conductive agent: binder 95: 3: 2.
in one embodiment, a button cell can be prepared by using the positive electrode and the negative electrode, adding a proper amount of electrolyte, and placing a separator. The electrolyte may be composed of a lithium salt and an organic solvent. And the separator may be a single-sided ceramic-coated Polyethylene (PE) separator. The button cell can be formed after being manufactured, so that a stable interface protective film is generated on the surface of the electrode pole piece. And carrying out charge and discharge treatment on the prepared button cell, and adjusting the charge state of the button cell to a target charge state. The target state of charge may be any state of charge. In one of the examples, the coin cell was adjusted to 4.2V for evaluation of the thermal decomposition characteristics of the ternary positive electrode active material at 4.2V.
And disassembling the button power battery reaching the target charge state in a glove box filled with argon to obtain an electrode pole piece. And (3) soaking the obtained electrode pole piece in a dimethyl carbonate solution for a period of time (usually half an hour), washing off residual lithium salt on the pole piece, and drying in a glove box in the whole process. And then scraping the second power battery electrode material from a current collector, and lightly grinding to obtain powder of the second power battery electrode material. And selecting a proper amount of the powder as the second power battery electrode material.
In S23, the second power cell electrode material may be placed in a sample preparation crucible of a differential scanning calorimeter. In one embodiment, the electrolyte can be optionally added or not added according to the test purpose, and sealing is performed to obtain the scanning calorimetry test sample. In one embodiment, the composition of the test sample is as follows: the ternary positive electrode active material + electrolyte has a mass ratio of 2: 1.
in one embodiment, a differential scanning calorimeter may be used to perform a scanning calorimetry test on the test sample at a selected temperature rise rate. The heating rate can be any one of 0.5 ℃/min, 1 ℃/min, 2 ℃/min, 5 ℃/min, 10 ℃/min, 15 ℃/min, 20 ℃/min, 30 ℃/min and 40 ℃/min. And obtaining a temperature-power relation curve of the test temperature data T and the test heat generation power data Q of the reaction of the second power battery electrode material through a scanning calorimetry test.
In S24, mathematical processing may be performed using the mathematical characteristics of the temperature-power relationship curve to obtain the reaction kinetic parameter value of the second power cell electrode material.
In one embodiment, the step S24 includes:
s241, obtaining peak temperature data of the temperature-power relation curve and a temperature rise rate value corresponding to the peak temperature data;
s242, establishing a reaction kinetic equation of the second power battery electrode material, and obtaining a heat generation power calculation formula of the second power battery electrode material according to a mass conservation equation, a heat release power calculation formula and the reaction kinetic equation;
s243, calculating the reaction kinetic parameter value according to the peak temperature data and the temperature rise rate value corresponding to the peak temperature data, a thermal analysis kinetic equation and the heat generation power calculation formula; and
and S244, obtaining the thermal decomposition reaction kinetic model according to the reaction kinetic equation, the heat generation power calculation formula and the reaction kinetic parameter value.
Before step S241, step 240 may be further included, in which the number of exothermic reactions of the second power battery electrode material is obtained according to the temperature-power relationship curve. In one embodiment, the temperature-power relationship curve obtained by a scanning calorimetry test at a temperature rise rate can be used for determining the number of reactions of the second power battery electrode material for thermal decomposition.
In one embodiment, in S243, the reaction kinetic parameter value is calculated by a numerical optimization method.
In one embodiment, the numerical optimization method may be a particle swarm optimization method, a genetic algorithm, a least squares method.
Referring to fig. 2, fig. 2 is a scanning calorimetry test result of the ternary cathode active material obtained in the embodiment of the present application at a temperature rise rate of 20 ℃/min. As shown in fig. 2, it can be determined that three heat-generating reactions exist in the tested ternary positive active material during thermal decomposition.
In S242, the reaction kinetic equation is:
Figure GDA0003208112580000091
the mass conservation equation is as follows:
Figure GDA0003208112580000092
the heat release power calculation formula is as follows:
Figure GDA0003208112580000093
wherein x represents the reaction of the second power cell electrode material; c. CxRepresents the second power battery electrode materialNormalized concentration of reactants for the reaction of (a), in units of 1; a. thexRepresents the forward factor of the reaction in units of s-1；Ea,xRepresents the activation energy of the reaction and has the unit of J.mol-1(ii) a R is an ideal gas constant 8.314 J.mol-1·K-1，nxIs the reaction order, the unit is 1, and T is the temperature of the second electrode material; qxRepresenting the exothermic power of the reaction; m represents the mass of the reactants in g; hxRepresents the reaction enthalpy of the reaction x of the second electrode material in the reaction kinetic parameters and has the unit of J.g-1；Ax，Ea,x,nxAnd HxRepresents the reaction kinetic parameters.
In one embodiment, the heat generation power calculation is:
Q＝Qx_1+Qx_2+Qx_3+… (4)
wherein the subscripts x _1, x _2, x _3 … represent the reaction of the different second power cell electrode materials.
In step S23, a differential scanning calorimeter may be used to perform a scanning calorimetry test on the test sample at a plurality of ramp rates. It is understood that at least 4 sets of scanning calorimetry tests of different ramp rates can be performed. Preferably, the heating scanning rate can be selected from 0.5 ℃/min, 1 ℃/min, 2 ℃/min, 5 ℃/min, 10 ℃/min, 15 ℃/min and 20 ℃/min. In an embodiment of the present application, 4 sets of temperature rise rate scanning calorimetry tests are performed, where the selected temperature rise rate is 5 ℃/min, 10 ℃/min, 15 ℃/min, and 20 ℃/min, the test results are shown in fig. 3, and fig. 3 is the calorimetry test result of the ternary cathode active material under the scanning rate condition.
Obtaining different heating rates beta according to the scanning calorimetry test result of the heating rateiPeak temperature T of each reaction underpi,x. In one embodiment, the thermoanalytical kinetic equation is:
Figure GDA0003208112580000101
for reaction x, the rate of temperature increase βiLower and peak temperature Tpi,xThere are conditions satisfying the above relationships.
Based on the relation (5), draw
Figure GDA0003208112580000102
The curve can be used for solving the forward factor A in the reaction kinetic equation of the second power battery electrode material reaction xxAnd activation energy Ea,x. In one embodiment, a partial reaction can be plotted if the peak temperature of the partial reaction is not well judged
Figure GDA0003208112580000103
Curve, and then solving to obtain forward factor AxAnd activation energy Ea,x。
Referring to FIG. 4, FIG. 4 shows exothermic reactions x _1 and x _2 in the calorimetric results
Figure GDA0003208112580000104
Curves and fitting results. Wherein beta isiRepresenting the rate of temperature rise. T ispi,xRepresenting the peak temperature. The forward factor and activation energy obtained from the fitting calculation were as follows: a. thex_1＝2.4262×1013，Ea,x_1＝1.6201×105，Ax_2＝6.5429×1013，Ea,x_2＝1.7785×105。
In one embodiment, according to the results of the scanning calorimetry test with multiple heating rates and the activation energy and forward factor of the partial decomposition reaction of the electrode material of the second power battery obtained in the above embodiment, an unknown reaction kinetic parameter [ A ] of the reaction x is givenx,Ea,x,nx,Hx]As the required quantity, the simultaneous formulas (1) to (4) can calculate and obtain different heating rates betaiThe electrode material of the second power battery generates heat power QiAnd temperature TiTemperature-power curve of (a). By using the numerical optimization method, the heat generation power Q and the heat generation power Q under multiple heating rates are obtained through calculationThe error between the temperature-power relation curve of the temperature T and the experimentally obtained scanning calorimetry test curve is minimum, so that a group of optimal reaction kinetic parameters [ A ] of all reactions x in the thermal decomposition process of the second power battery electrode material can be obtainedx,Ea,x,nx,Hx]。
In one embodiment, the ternary positive electrode active material was subjected to calorimetric tests under 4 sets of different scan rate conditions. The 4 sets of scan rates are {5 ℃/min, 10 ℃/min, 15 ℃/min, 20 ℃/min }. With continued reference to fig. 2, the ternary positive electrode active material undergoes three heat-generating reactions during thermal decomposition, denoted as x _1, x _2, and x _ 3. Based on the equations (1) - (4) and the partial reaction kinetic parameters determined in the above embodiments, the least square method is used to minimize the error between the temperature-power relationship curve of the heat generation power Q and the temperature T at multiple temperature rise rates obtained by calculation and the curve of the scanning calorimetry test obtained by experiments, i.e. a set of optimal reaction kinetic parameters [ a ] of each reaction x of the thermal decomposition of the ternary cathode active material can be obtainedx,Ea,x,nx,Hx]And reaction enthalpy HxThe optimal set of parameters obtained is shown in table 1.
TABLE 1 reaction kinetics parameters of all reactions during the thermal decomposition of the electrode materials in the examples of the present application
Figure GDA0003208112580000111
The thermal decomposition reaction kinetic model can be established by equations (1) to (4) by substituting the above-described optimum parameters into equations (1) to (4).
Referring to fig. 5, fig. 5 is a graph comparing the calculation results and the experimental results of the thermal decomposition reaction kinetic model established in the examples of the present application. It can be seen from fig. 5 that the calculated results are very close to the experimental results, indicating that the values of the reaction kinetic parameters obtained by the above-mentioned example calculations are very accurate. Therefore, the thermal decomposition reaction kinetic model provided by the embodiment of the application can accurately predict the heat generation characteristics of the first power battery electrode material in the thermal decomposition process, and can be used for quantitatively evaluating the thermal stability of the electrode material.
Referring to fig. 6, an apparatus for determining thermal stability of an electrode material of a power battery according to an embodiment of the present application includes a device 11 for determining thermal stability of an electrode material of a power battery and a computer 12. The computer 12 includes a memory 100 and a processor 200. The memory 200 may have stored therein a computer program 300. The computer program 300 may be run on the processor 200. The processor 200 executes the computer program 300 and adopts a battery electrode material thermal stability judgment method, which includes:
s10, selecting temperature data of the electrode material of the first power battery;
s20, obtaining heat generation power data of the first power battery electrode material according to the temperature data of the first power battery electrode material and a thermal decomposition reaction kinetic model of the electrode material; and
and S30, comparing the heat generation power data with a standard value, and judging the thermal stability of the first power battery electrode material.
The embodiment of the application also provides a computer readable storage medium. The computer-readable storage medium has stored thereon a computer program which, when being executed by a processor, is operative to carry out the steps of the method.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware related to a computer program or instructions, and the program can be stored in a computer readable storage medium, and when executed, the program can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (9)

1. A method for judging the thermal stability of an electrode material of a power battery is characterized by comprising the following steps:
s10, selecting temperature data of the electrode material of the first power battery;
s20, obtaining heat generation power data of the first power battery electrode material according to the temperature data of the first power battery electrode material and a thermal decomposition reaction kinetic model of the electrode material; and
s30, comparing the heat generation power data with a standard value, and judging the thermal stability of the first power battery electrode material;
in S20, the method for building the thermal decomposition reaction kinetic model includes:
s21, providing a second power battery, and carrying out battery charging and discharging processing on the second power battery;
s22, disassembling the second power battery after the charging and discharging treatment to obtain a second power battery electrode material;
s23, selecting a temperature rise rate value, and carrying out scanning calorimetry test on the second power battery electrode material according to the temperature rise rate value to obtain a temperature-power relation curve of test temperature data and test heat generation power data of the reaction of the second power battery electrode material; and
and S24, calculating the reaction kinetic parameter value of the electrode material of the second power battery according to the temperature-power relation curve, and obtaining the thermal decomposition reaction kinetic model according to the reaction kinetic parameter value.
2. The method for determining the thermal stability of the power battery electrode material according to claim 1, wherein the step S24 includes:
s241, obtaining peak temperature data of the temperature-power relation curve and a temperature rise rate value corresponding to the peak temperature data;
s242, establishing a reaction kinetic equation of the second power battery electrode material, and obtaining a heat generation power calculation formula of the second power battery electrode material according to a mass conservation equation, a heat release power calculation formula and the reaction kinetic equation;
s243, calculating the reaction kinetic parameter value according to the peak temperature data and the temperature rise rate value corresponding to the peak temperature data, a thermal analysis kinetic equation and the heat generation power calculation formula; and
and S244, obtaining the thermal decomposition reaction kinetic model according to the reaction kinetic equation, the heat generation power calculation formula and the reaction kinetic parameter value.
3. The method for determining thermal stability of an electrode material of a power battery according to claim 2, wherein in S242, the reaction kinetic equation is as follows:
Figure FDA0003208112570000021
the mass conservation equation is as follows:
Figure FDA0003208112570000022
the heat release power calculation formula is as follows:
Figure FDA0003208112570000023
wherein x represents the reaction of the second power cell electrode material; c. CxA normalized concentration of a reactant representing a reaction of the second power cell electrode material in units of 1; a. thexRepresents the forward factor of the reaction in units of s-1；Ea,xRepresents the activation energy of the reaction and has the unit of J.mol-1(ii) a R is an ideal gas constant 8.314 J.mol-1·K-1，nxIs the reaction stage number, the unit is 1, and T is the temperature of the second electrode material; qxRepresentative of said heat release power; m represents the mass of the reactants in g; hxRepresents the reaction enthalpy of the reaction x of the second electrode material in the reaction kinetic parameters and has the unit of J.g-1；Ax，Ea,x,nxAnd HxRepresents the reaction kinetic parameter and t represents time.
4. The method for determining the thermal stability of the power battery electrode material according to claim 3, wherein the heat generation power calculation formula is as follows:
Q＝Qx_1+Qx_2+Qx_3+… (4)
wherein the subscripts x _1, x _2, x _3 … represent the reaction of the different second electrode materials, Qx_1，Qx_2，Qx_3… … represent the heat-generating power of the different reactions of the second electrode material.
5. The method for judging the thermal stability of the power battery electrode material according to claim 4, wherein the thermal analysis kinetic equation is as follows:
Figure FDA0003208112570000024
wherein, betaiRepresenting said rate of rise value, Tpi,xRepresenting the peak temperature data.
6. The method for determining the thermal stability of the power battery electrode material according to claim 2, wherein before S241, the method further comprises:
and S240, obtaining the number of exothermic reactions of the electrode material of the second power battery according to the temperature-power relation curve.
7. The method for determining thermal stability of an electrode material of a power battery according to claim 2, wherein in S243, the reaction kinetic parameter value is calculated by a numerical optimization method.
8. A power battery electrode material thermal stability determination apparatus, comprising a power battery electrode material thermal stability determination device (11) and a computer (12), wherein the computer (12) comprises a memory (100), a processor (200) and a computer program (300) stored on the memory (100) and operable on the processor (200), characterized in that the processor (200) adopts a power battery electrode material thermal stability determination method when executing the computer program (300), the method comprising:
s10, selecting temperature data of the electrode material of the first power battery;
s20, obtaining heat generation power data of the first power battery electrode material according to the temperature data of the first power battery electrode material and a thermal decomposition reaction kinetic model of the electrode material; and
s30, comparing the heat generation power data with a standard value, and judging the thermal stability of the first power battery electrode material;
in S20, the method for building the thermal decomposition reaction kinetic model includes:
s21, providing a second power battery, and carrying out battery charging and discharging processing on the second power battery;
s22, disassembling the second power battery after the charging and discharging treatment to obtain a second power battery electrode material;
s23, selecting a temperature rise rate value, and carrying out scanning calorimetry test on the second power battery electrode material according to the temperature rise rate value to obtain a temperature-power relation curve of test temperature data and test heat generation power data of the reaction of the second power battery electrode material; and
and S24, calculating the reaction kinetic parameter value of the electrode material of the second power battery according to the temperature-power relation curve, and obtaining the thermal decomposition reaction kinetic model according to the reaction kinetic parameter value.
9. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, is adapted to carry out the steps of the method of any one of claims 1 to 7.
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