CN117783867A - Battery overpotential test calculation method - Google Patents
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- CN117783867A CN117783867A CN202311580635.9A CN202311580635A CN117783867A CN 117783867 A CN117783867 A CN 117783867A CN 202311580635 A CN202311580635 A CN 202311580635A CN 117783867 A CN117783867 A CN 117783867A
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- 238000012360 testing method Methods 0.000 title claims abstract description 55
- 238000004364 calculation method Methods 0.000 title claims abstract description 21
- 238000000034 method Methods 0.000 claims abstract description 20
- 238000007599 discharging Methods 0.000 claims abstract description 16
- 230000001105 regulatory effect Effects 0.000 claims description 5
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 17
- 229910001415 sodium ion Inorganic materials 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Abstract
The invention discloses a battery overpotential test calculation method. The method comprises the following steps: selecting a plurality of temperature points, discharging a plurality of batteries to be tested at different current densities, recording the discharged temperatures and the discharged current densities, and calculating the overpotential of the batteries; based on the temperature, the current density and the overpotential data, a first curve taking the temperature as a variable and the overpotential as a function is manufactured, a first function formula is obtained, and a second curve taking the overpotential as a variable and the current density as a function is manufactured, and a second function formula is obtained; over-potentials at other temperatures are calculated based on the first functional formula, and over-potentials at other current densities are calculated based on the second functional formula. The invention can calculate the overpotential under other temperature and current conditions, thereby calculating the power according to the calculated overpotential.
Description
Technical Field
The invention relates to the technical field of battery overpotential processing methods, in particular to a battery overpotential test calculation method.
Background
The power battery is a core component of the electric automobile, the charge and discharge power capacity of the electric automobile is determined by the power capacity of a single battery, and accurate and efficient measurement of the power capacity of the battery is an important aspect for evaluating the performance of the battery. Current methods of evaluating battery power capability are to conduct actual tests at a given temperature, pulse current, pulse time, state of charge (SOC), record the potential under that condition, and determine its power capability. Determining power under different SOC, different temperature, different current conditions requires a number of cumbersome tests and longer cycles. Therefore, there is an urgent need to propose a new battery overpotential test calculation method to determine battery power.
Disclosure of Invention
The invention aims at solving the technical defects existing in the prior art and provides a battery overpotential test calculation method.
The technical scheme adopted for realizing the purpose of the invention is as follows:
a battery overpotential test calculation method includes the steps:
selecting a plurality of temperature points, respectively discharging a plurality of batteries to be tested at different current densities, recording the discharged temperatures and the discharged current densities, and calculating the overpotential of the batteries;
based on the temperature, the current density and the overpotential data, a first curve taking the temperature as a variable and the overpotential as a function is manufactured, a first function formula is obtained, and a second curve taking the overpotential as a variable and the current density as a function is manufactured, and a second function formula is obtained;
over-potentials at other temperatures are calculated based on the first functional formula, and over-potentials at other current densities are calculated based on the second functional formula.
The temperature points are at least four temperatures, and the current densities of the discharge with different current densities are at least three different current densities.
Wherein the temperature is selected from-30deg.C to 55deg.C, and the current density is 0.1mA/cm 2 To 1.50mA/cm 2 Is selected.
Wherein, when the first curve is made by taking temperature as a variable and overpotential as a function, the adopted temperature value is Kelvin unit.
When the battery to be tested is discharged in a plurality of different current densities, a continuous discharging mode is adopted for discharging.
Before discharging the battery to be tested at a plurality of different current densities, firstly testing an open circuit voltage U0 of a reference battery identical to the battery to be tested, wherein the open circuit voltage U0 is used for calculating an overpotential, and the method comprises the following steps:
and (3) placing the selected reference battery at a preset temperature, charging to a cut-off voltage at a preset current density, then charging to a low current density at a constant voltage, discharging to a preset voltage at the preset current density, obtaining the rated capacity of the battery, calculating the rated capacity to obtain the SOC of the battery, regulating the SOC of the battery at the same temperature by using 1C current, standing for a period of time at intervals of 5% of the SOC, and testing and recording the open circuit voltage U0 of the battery.
When the battery to be tested is tested, the battery to be tested is charged to 100% SOC at a preset current density at a preset temperature, and then the temperature of the battery is respectively adjusted to a plurality of temperature points.
When a plurality of different current density discharge tests are respectively carried out on a battery to be tested, the discharge capacity Q2 and the voltage U2 of the battery are recorded at intervals of preset time, the SOC corresponding to each voltage value under a certain test strip temperature and a certain current density is calculated through the discharge capacity Q2 and the voltage U2 of the battery, the overpotential corresponding to each temperature, each SOC and each current density is calculated, a first curve taking the temperature as a variable and the overpotential as a function is manufactured through the data of the current density, the temperature and the overpotential, a first function formula is obtained, and a second curve taking the overpotential as a variable and the current density as a function is obtained.
Wherein the value of the preset time ranges from 0.5 seconds to 60 seconds, and is preferably 1 second.
And discharging to a cut-off voltage when the battery to be tested is discharged at a plurality of different current densities respectively.
According to the battery overpotential test calculation method, a small number of batteries are tested, a corresponding function formula is obtained according to test data, then the overpotential is directly calculated by utilizing the function formula, so that the overpotential under other temperature and other current conditions can be accurately calculated, the power of the battery can be calculated according to the calculated overpotential, and then resources such as a battery sample for testing, testing time and testing equipment are saved.
Drawings
Fig. 1 is a flowchart of a battery overpotential test calculation method according to an embodiment of the present invention.
FIG. 2 is a graph of 50% SOC, 0.4mA/cm for an embodiment of the invention 2 Temperature-overpotential curve under current conditions.
FIG. 3 is a temperature-overpotential curve for other SOCs and other current conditions for an embodiment of the present invention.
FIG. 4 is an overpotential-current density curve for the example of the present invention at-10℃under 30% SOC.
Detailed Description
The invention is described in further detail below with reference to the drawings and the specific examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Term interpretation:
overpotential: at a certain temperature and a certain SOC, the difference between the open-circuit voltage of the battery and the voltage of the battery in a charge-discharge state.
According to the B-V equation, under a certain temperature and a certain SOC, the current and the overpotential form a certain functional relation; according to the Arrhenii Wu Ci equation, the overpotential at a certain current density is a function of temperature. Therefore, the scheme of the battery overpotential test calculation method of the present invention is as follows with reference to fig. 1:
s1, selecting a plurality of temperature points, respectively discharging a plurality of batteries to be tested with different current densities, recording the discharged temperatures and the discharged current densities, and calculating the overpotential of the batteries;
s2, manufacturing a first curve which takes temperature as a variable and takes overpotential as a function, obtaining a first function formula, and manufacturing a second curve which takes overpotential as a variable and takes current density as a function, and obtaining a second function formula;
s3, calculating overpotential under other temperatures based on the first function formula, and calculating overpotential under other current densities based on the second function formula.
Through the processing, the overpotential at any temperature and any current can be calculated, so that the calculation of the power of the battery is realized based on the overpotential, a large number of test flows can be omitted, and test equipment, battery samples and test time are saved.
In a specific embodiment, in step S1, the temperature points are at least four temperatures, and the different current densities are at least three different current densities; the selected temperature points are too few, so that the acquisition of data is not facilitated to obtain a more accurate first curve and a second curve and corresponding function formulas, the subsequent calculation of overpotential at other temperatures and under current density is not facilitated, and likewise, the selected different current density values are too few, so that the acquisition of data is not facilitated to obtain a more accurate first curve and a more accurate second curve and corresponding function formulas, and the subsequent calculation of overpotential at other temperatures and under current density is not facilitated.
Preferably, the temperature is selected between-30 ℃ and 55 ℃, and the current density is 0.1mA/cm 2 To 1.50mA/cm 2 Is selected. When the battery is tested, the temperature is less than 55 ℃, and is more than-30 ℃, side reactions in the battery can be caused by high temperature, impedance rise is caused, and the battery cannot work normally due to high impedance caused by low temperature, so that the temperature in the range of-30 ℃ to 55 ℃ is suitable for testing, and the problem caused by overhigh or overlow temperature is avoided. Too high a current density can cause self-heating of the battery, resulting in disturbed impedance test results. The test time with too low current density is too long, and comprehensively considered, the current test is selected to be 0.1-1.5mA/cm 2 And selecting in a range.
In order to facilitate data processing, in the embodiment of the present application, when a first curve is made that uses temperature as a variable and overpotential as a function, the temperature value used is in kelvin.
In step S1, when the battery to be tested is discharged at a plurality of different current densities, the battery to be tested is continuously discharged in a continuous discharging manner, so that a better discharging effect can be achieved.
Since the overpotential is calculated and the calculation of the overpotential requires an open circuit of the battery, the open circuit voltage U0 of the reference battery identical to the battery to be tested is first tested before the battery to be tested is discharged at a plurality of different current densities, and the open circuit voltage U0 is used for calculating the overpotential, and the method comprises the following steps:
the selected reference cell is subjected to a predetermined temperature (e.g., 25 ℃) at a predetermined current density (e.g., 0.4mA/cm 2 ) After charging to the off-voltage, the battery is charged at a constant voltage to a low current density (e.g., 0.1mA/cm 2 ) Finally at a predetermined current density, e.g. 0.4mA/cm 2 ) Discharging to a preset voltage to obtain the rated capacity of the battery, calculating the SOC of the battery based on the rated capacity, adjusting the SOC of the battery by using 1C current, standing for 1 hour at intervals of 5% SOC, and testing and recording the open circuit voltage U0 (0% -100% SOC) of the battery.
Through the above steps, after obtaining the open circuit voltage of the battery, the battery to be tested is tested at a predetermined temperature (e.g., 25 ℃) and with a predetermined current density (e.g., 0.4mA/cm 2 ) And (3) charging the test battery to 100% of SOC, then respectively adjusting the temperature of the battery to a plurality of temperature points, then discharging at different current densities, recording the discharged temperature and current density, collecting corresponding data, and calculating the over-potential of the battery at each temperature, each SOC and each current density based on the collected data.
Specifically, when the battery to be tested is subjected to a plurality of different current density discharge tests, the discharge capacity Q2 and the voltage U2 of the battery are recorded at intervals of a predetermined time, preferably, the interval of the predetermined time ranges from 0.5 seconds to 60 seconds, and more preferably, 1 second.
After the battery discharge capacity Q2 and the voltage U2 are recorded, the SOC corresponding to each voltage value at a certain test temperature and a certain current density can be calculated through the battery discharge capacity Q2 and the voltage U2, the overpotential corresponding to each temperature, each SOC and each current density is calculated, a first curve (temperature-overpotential curve) taking the temperature as a variable and the overpotential as a function is manufactured through the data of the current density, the temperature and the overpotential, a first function formula is obtained, a second curve (overpotential-current density curve) taking the overpotential as a variable and the current density as a function is obtained, and a second function formula is obtained.
The following describes the implementation steps of the battery overpotential test calculation method according to the embodiment of the present invention in detail. The following description will be made taking a sodium ion battery as an example, but the present invention is not limited to a sodium ion battery, and may be applied to other batteries such as a lithium ion battery, and is not limited to a sodium ion battery.
A sodium ion battery to be tested is taken and placed in an environment box, the temperature of the environment box is regulated to 25 ℃, and the temperature is regulated to 0.4mA/cm 2 The battery was charged until the cut-off voltage was 3.9V, and the constant voltage was charged to a current of 0.1mA/cm at 3.9V 2 Then at 0.4mA/cm 2 To 1.5V, to obtain the rated capacity Q0 of the battery.
The sodium ion battery has a certain SOC value taking Q0 as denominator and the charge Q1 at this time as numerator, i.e. soc=q1/Q0. Under the environment of 25 ℃, the SOC is regulated by 1C current (1C current is defined as that the battery is charged at constant current, the battery is charged from 0% SOC to 100% SOC after 1 hour, the current is 1C at this time), the battery is kept stand for 1 hour every 5% SOC, and the open circuit voltage U0 (0% -100% SOC) of the battery is tested and recorded for the calculation of the overpotential in the subsequent battery test.
Example 1
Taking a sodium ion battery to be tested, and taking the sodium ion battery to be tested at the environmental temperature of 25 ℃ and the concentration of 0.4mA/cm 2 Charging the battery to 100% SOC at current density, and then respectively adjusting the temperature of the battery to 25 ℃,10 ℃,0 ℃ and-20 ℃; the three sodium ion batteries to be tested were each at 0.2mA/cm 2 、0.4mAh/cm 2 、0.6mA/cm 2 The current density is discharged to a cut-off voltage (1.5V), and the discharge capacity Q2 and the voltage U2 of the battery are recorded every 1 second (the interval time range is selected from 0.5 second to 60 seconds) in the discharging process; calculating SOC=Q2/Q0 corresponding to each voltage value under a certain test condition (at a certain temperature and a certain current density), and reading the corresponding voltage value U2 every 5% SOC; the overpotential Δu=u0-U2 corresponding to each temperature, each SOC, and each current density was calculated.
Converting the temperature value from a unit of degrees Celsius to a unit of Kelvin at 0.2mA/cm 2 、0.4mA/cm 2 、0.6mA/cm 2 Each SOC pair obtainedThe overpotential delta U is used as a function value and a vertical axis y value, the temperature values of 293, 283, 273 and 253K in Kelvin units are used as a variable value and a horizontal axis x value, a temperature-overpotential delta U curve and a corresponding function formula are obtained, and then the overpotential delta U of other temperatures is calculated according to the function formula corresponding to the temperature-overpotential delta U curve.
At 0.2mA/cm 2 、0.4mA/cm 2 、0.6mA/cm 2 The current density value is a function value and an ordinate y value, the overpotential delta U under each temperature and each SOC condition is a variable value and an abscissa x value, an overpotential delta U-current density relation curve and a function formula are obtained, and then the overpotential delta U corresponding to other current densities is calculated according to the function formula corresponding to the overpotential delta U-current density relation curve.
Example 2
Taking a sodium ion battery to be tested, and taking the sodium ion battery to be tested at the environmental temperature of 25 ℃ and the concentration of 0.4mA/cm 2 Charging the battery to 100% SOC at current density, and then respectively adjusting the temperature of the battery to 55 ℃,45 ℃,0 ℃ and-10 ℃; the three sodium ion batteries to be tested were each at 0.5mA/cm 2 、1.0mAh/cm 2 、1.5mA/cm 2 The current density discharges to a cut-off voltage (1.5V). Recording the discharge capacity Q2 and the voltage U2 of the battery every 2 seconds (the interval time range is selected from 0.5 seconds to 60 seconds) in the discharge process; calculating SOC=Q2/Q0 corresponding to each voltage value under a certain test condition (at a certain temperature and a certain current density), and reading the corresponding voltage value U2 every 5% SOC; the overpotential Δu=u0-U2 corresponding to each temperature, each SOC, and each current density was calculated.
Converting the temperature value from a unit of degrees Celsius to a unit of Kelvin at 0.5mA/cm 2 、1.0mAh/cm 2 、1.5mA/cm 2 And the obtained SOC corresponds to the overpotential delta U as a function value and a vertical axis y value, the Kelvin unit temperature value is taken as a variable value and a horizontal axis x value, a temperature-overpotential delta U curve and a corresponding function formula are obtained, and then the overpotential delta U of other temperatures is calculated according to the function formula corresponding to the temperature-overpotential delta U curve.
At 0.5mA/cm 2 、1.0mAh/cm 2 、1.5mA/cm 2 The current density value is a function value and an ordinate y value, and the temperatures are used for eachThe overpotential delta U under each SOC condition is a variable value and an abscissa x value, so that an overpotential delta U-current density relation curve and a function formula are obtained, and the overpotential delta U corresponding to other current densities can be calculated according to the function formula corresponding to the overpotential delta U-current density relation curve.
Example 3
Taking a sodium ion battery to be tested, and taking the sodium ion battery to be tested at the environmental temperature of 25 ℃ and the concentration of 0.4mA/cm 2 Charging the battery to 100% SOC at current density, and then respectively adjusting the temperature of the battery to 25 ℃,10 ℃,0 ℃ and minus 30 ℃; the three sodium ion batteries to be tested were each at 0.1mA/cm 2 、0.2mAh/cm 2 、0.3mA/cm 2 The current density discharges to a cut-off voltage (1.5V). Recording the discharge capacity Q2 and the voltage U2 of the battery every 3 seconds (the interval time range is selected from 0.5 seconds to 60 seconds) in the discharge process; calculating SOC=Q2/Q0 corresponding to each voltage value under a certain test condition (at a certain temperature and a certain current density), and reading the corresponding voltage value U2 every 5% SOC; the overpotential Δu=u0-U2 corresponding to each temperature, each SOC, and each current density was calculated.
Converting the temperature value from a unit of degrees Celsius to a unit of Kelvin at 0.1mA/cm 2 、0.2mAh/cm 2 、0.3mA/cm 2 And the obtained SOC corresponds to the overpotential delta U as a function value and a vertical axis y value, the temperature value in Kelvin units is taken as a variable value and a horizontal axis x value, a temperature-overpotential delta U curve and a corresponding function formula are obtained, and then the overpotential delta U of other temperatures is calculated according to the function formula corresponding to the temperature-overpotential delta U curve.
At 0.1mA/cm 2 、0.2mAh/cm 2 、0.3mA/cm 2 The current density value is a function value and an ordinate y value, the overpotential delta U under each temperature and each SOC condition is a variable value and an abscissa x value, an overpotential delta U-current density relation curve and a function formula are obtained, and then the overpotential delta U corresponding to other current densities can be calculated according to the function formula corresponding to the overpotential delta U-current density relation curve.
Comparative example 1
Taking a sodium ion battery to be tested, and taking the sodium ion battery to be tested at the environmental temperature of 25 ℃ and the concentration of 0.4mA/cm 2 Current density across the batteryCharging to 100% SOC, and then respectively adjusting the temperature of the battery to 80 ℃,70 ℃,60 ℃ and minus 40 ℃; the three sodium ion batteries to be tested were each at 2.0mA/cm 2 、4.0mAh/cm 2 、6.0mA/cm 2 The current density discharges to a cut-off voltage (1.5V). Recording the discharge capacity Q2 and the voltage U2 of the battery every 5 seconds (the interval time range is selected from 0.5 seconds to 60 seconds) in the discharge process; calculating SOC=Q2/Q0 corresponding to each voltage value under a certain test condition (at a certain temperature and a certain current density), and reading the corresponding voltage value U2 every 5% SOC; the overpotential Δu=u0-U2 corresponding to each temperature, each SOC, and each current density was calculated.
Converting the temperature value from a unit of degrees Celsius to a unit of Kelvin at 2.0mA/cm 2 、4.0mAh/cm 2 、6.0mA/cm 2 And the obtained SOC corresponds to the overpotential delta U as a function value and a vertical axis y value, the temperature value in Kelvin units is taken as a variable value and a horizontal axis x value, a temperature-overpotential delta U curve and a corresponding function formula are obtained, and then the overpotential delta U of other temperatures is calculated according to the function formula corresponding to the temperature-overpotential delta U curve.
At 2.0mA/cm 2 、4.0mAh/cm 2 、6.0mA/cm 2 The current density value is a function value and an ordinate y value, the overpotential delta U under each temperature and each SOC condition is a variable value and an abscissa x value, an overpotential delta U-current density relation curve and a function formula are obtained, and then the overpotential delta U corresponding to other current densities is calculated according to the function formula corresponding to the overpotential delta U-current density relation curve.
Referring to FIG. 2, FIG. 2 shows a 50% SOC, 0.4mA/cm 2 Temperature-overpotential curve under current conditions, function y=0.0003× 2 0.154 x= 22.958, by which the overpotential at the corresponding temperature can be calculated, verified to be measured at 0.4mA/cm in fig. 2 2 The measured and calculated values of overpotential at-5 ℃ (268K), -10 ℃ (263K), -30 ℃ (243K) were very small in error under 50% soc conditions.
FIG. 3 is a graph of temperature vs. overpotential for other SOC and other current conditions.
FIG. 4 shows the relationship of DeltaU-current density at-10deg.C and 30% SOC,the corresponding function formula is y= 8.1215x 2 3.146 x= 0.4131, by means of which the overpotential at the corresponding current density can be calculated. The error between the calculated value of the overpotential calculated by the functional formula and the measured value of the corresponding condition is very small.
In contrast, in comparative example 1, the calculated value and the measured value obtained by the method of the present invention have great errors, which indicates that the calculation of the overpotential Δu at other temperatures and other current densities cannot be effectively performed by the methods of examples 1 to 3 of the present invention at such temperatures and current densities.
Table 1 is data of current densities and different temperature parameter ranges of different discharges used when testing the battery to be tested in examples 1 to 3 and comparative examples, making a first curve with temperature as a function of overpotential and a second curve with overpotential as a function of current density.
TABLE 1
Through tests, the three current flow degrees of the comparative example 1 exceed the upper limit of the current density set by the application, and the battery heats, so that the measured overpotential error is larger; the selected temperature range exceeds the upper limit of the highest temperature set by the application, and side reactions occur in the battery, so that the test deviation is larger; the temperature range selected exceeds the lower limit, resulting in a faster battery voltage drop and a correspondingly larger overpotential deviation, demonstrating the temperature range of-30 to 55 ℃ and 0.1mA/cm of the present application 2 And 1.50mA/cm 2 The current density meets the test requirements.
In order to verify the effectiveness of the method, the method is effective by carrying out multiple times of verification and testing at different temperatures, pulse current densities, pulse times (test times) and SOCs, and the error between the calculated value and the measured value is not large and is within an acceptable range. Table 2 shows calculated and measured overpotential values under the conditions of corresponding temperature, SOC and current by the method of the present invention.
TABLE 2
If the method of the invention is not adopted, in order to obtain the overpotential of the battery, the actual test is required according to the requirements of three dimensions of temperature, current and SOC, thus each test needs more time, more test equipment and more battery samples, the test time is long and the cost is high.
While the fundamental and principal features of the invention and advantages of the invention have been shown and described, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but may be embodied in other specific forms without departing from the spirit or essential characteristics thereof;
the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in detail below, and that the embodiments described in the examples may be combined as appropriate to form other embodiments that will be apparent to those skilled in the art.
Claims (10)
1. The battery overpotential test calculation method is characterized by comprising the following steps:
selecting a plurality of temperature points, respectively discharging a plurality of batteries to be tested at different current densities, recording the discharged temperatures and the discharged current densities, and calculating the overpotential of the batteries;
based on the temperature, the current density and the overpotential data, a first curve taking the temperature as a variable and the overpotential as a function is manufactured, a first function formula is obtained, and a second curve taking the overpotential as a variable and the current density as a function is manufactured, and a second function formula is obtained;
over-potentials at other temperatures are calculated based on the first functional formula, and over-potentials at other current densities are calculated based on the second functional formula.
2. The method of claim 1, wherein the temperature point is at least four temperatures and the current density of the different current density discharges is at least three different current densities.
3. The method of claim 1, wherein the temperature is selected from the range of-30 ℃ to 55 ℃ and the current density is 0.1mA/cm 2 To 1.50mA/cm 2 Is selected.
4. The method of claim 1, wherein the first curve is generated as a function of temperature and the overpotential is measured in kelvin.
5. The method according to claim 1, wherein when the battery to be tested is discharged at a plurality of different current densities, the battery to be tested is discharged in a continuous discharge manner.
6. The battery overpotential test calculation method of claim 1, wherein before discharging the battery to be tested at a plurality of different current densities, respectively, an open circuit voltage U0 of a reference battery identical to the battery to be tested is first tested, the open circuit voltage U0 being used to calculate the overpotential, comprising:
and (3) placing the selected reference battery at a preset temperature, charging to a cut-off voltage at a preset current density, then charging to a low current density at a constant voltage, discharging to a preset voltage at the preset current density, obtaining the rated capacity of the battery, calculating the rated capacity to obtain the SOC of the battery, regulating the SOC of the battery at the same temperature by using 1C current, standing for a period of time at intervals of 5% of the SOC, and testing and recording the open circuit voltage U0 of the battery.
7. The battery overpotential test calculation method of claim 1, wherein the test battery is charged to 100% soc at a predetermined current density at a predetermined temperature and then the battery temperature is adjusted to a plurality of the temperature points, respectively, when the battery to be tested is tested.
8. The method according to claim 1, wherein when the battery to be tested is subjected to a plurality of different current density discharge tests, the battery discharge capacity Q2 and the voltage U2 are recorded at intervals of a predetermined time, the SOC corresponding to each voltage value at a certain test strip temperature and a certain current density is calculated by the battery discharge capacity Q2 and the voltage U2, the overpotential corresponding to each temperature, each SOC, and each current density is calculated, and a first curve with the temperature as a function and the overpotential as a function is prepared by the data of the current density, the temperature and the overpotential to obtain a first function formula, and a second curve with the overpotential as a function and the current density as a function to obtain a second function formula.
9. The battery overpotential test calculation method of claim 8, wherein the predetermined time is in a range of 0.5 seconds to 60 seconds, preferably 1 second.
10. The method according to claim 1, wherein the battery to be tested is discharged to a cut-off voltage when a plurality of different current densities are discharged, respectively.
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