Method and device for measuring battery exchange current density, computer equipment and medium

Abstract

The invention provides a battery exchange current density measurement method and device, computer equipment and a computer readable storage medium, and relates to the technical field of battery detection. The battery exchange current density measurement method comprises the following steps: carrying out preset pulse current discharge on a to-be-measured battery in a preset environment; acquiring a voltage change value of the to-be-tested battery in the preset discharge time; determining the internal resistance of the to-be-detected battery based on the voltage change value and the preset pulse current; obtaining the effective reaction area of the electrode of the to-be-detected battery; and determining the exchange current density of the to-be-tested battery based on the effective reaction area of the electrode, the internal resistance of the to-be-tested battery and the temperature of the preset environment. By using the method, the exchange current density of the battery can be quickly and accurately measured.

Description

Technical Field

[0001] The present application relates to the field of battery detection technology, and in particular to a method, device, computer equipment and computer-readable storage medium for measuring battery exchange current density. Background Art

[0002] The exchange current density of a battery can be used as one of the performance indicators for evaluating a battery. The exchange current density is an important parameter for characterizing the reversibility of an electrode reaction. Its physical meaning is the absolute value of the current density of the anode reaction and the cathode reaction in two reaction directions. It is mainly used to describe the ability of an electrode material to gain or lose electrons. In addition to being affected by temperature, its size is also related to the properties of the electrode reaction and the electrode material. The greater the exchange current density, the stronger the ability to participate in the redox reaction current, and the better the electrochemical reversibility during the charge and discharge process. Conversely, the weaker the ability to participate in the redox reaction current, the worse the electrochemical reversibility during the charge and discharge process.

[0003] Currently, the measurement process of battery exchange current density is relatively complicated. Summary of the invention

[0004] In view of the above, it is necessary to provide a method, device, computer equipment and computer-readable storage medium for measuring battery exchange current density, which can solve the problem of complex battery exchange current density measurement process.

[0005] In a first aspect, the present application provides a method for measuring battery exchange current density, comprising: discharging a battery to be tested in a preset environment with a preset pulse current; obtaining a voltage change value of the battery to be tested within a preset discharge time; determining an internal resistance of the battery to be tested based on the voltage change value and the preset pulse current; obtaining an effective reaction area of ​​an electrode of the battery to be tested; and determining the exchange current density of the battery to be tested based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested, and the temperature of the preset environment.

[0006] By adopting the above technical scheme, the internal resistance of the battery to be tested is quickly calculated based on the voltage drop caused by the ohmic polarization and electrochemical polarization of the battery under the specified discharge current and the corresponding preset pulse current. Then, based on the internal resistance of the battery to be tested, the measured ambient temperature and the effective reaction area of ​​the electrode, the exchange current density of the battery to be tested discharged at the ambient temperature can be quickly determined. The measurement takes a short time, is simple and low in cost, and has high accuracy, and can monitor the exchange current density of the battery in the discharge state in real time.

[0007] In one possible implementation, the exchange current density of the battery to be tested is determined based on the following formula: i0=(R×T) / (A×F×R t ), Among them, i0 is the exchange current density of the battery to be tested, R is the gas constant, T is the temperature of the preset environment, A is the effective reaction area of ​​the electrode, F is the Faraday constant, and R t is the internal resistance of the battery to be tested.

[0008] By adopting the above technical solution, the exchange current density of the battery to be tested discharged at a specified ambient temperature can be accurately calculated through the above formula.

[0009] In a possible implementation, the preset discharge time is 1 second from the start of discharging the battery to be tested using a preset pulse current.

[0010] By adopting the above technical solution, the discharge of the 1s pulse current can make the internal resistance of the battery to be tested basically in the state of ohmic internal resistance and electrochemical internal resistance, thereby realizing accurate determination of the internal resistance of the battery to be tested based on the voltage change value and the discharge current.

[0011] In a possible implementation, the measurement method further includes: obtaining the surface area of ​​the active material particles coated on the electrode of the battery to be tested and the electrode porosity; and determining the effective reaction area of ​​the electrode based on the surface area of ​​the active material particles and the electrode porosity.

[0012] By adopting the above technical solution, based on the surface area of ​​the active material particles coated on the electrode of the battery to be tested and the porosity of the electrode, the effective reaction area of ​​the electrode of the battery to be tested can be accurately calculated.

[0013] In a possible implementation, the preset environment is a constant temperature environment whose ambient temperature is a preset value, and the preset pulse current is greater than or equal to 2C.

[0014] By adopting the above technical solution, since the exchange current density of the battery is related to the temperature, by setting a constant temperature measurement environment, the exchange current density of the battery to be tested at the temperature can be accurately obtained. By setting the preset pulse current greater than or equal to 2C, it is beneficial to make the discharge of the 1s pulse current cause the internal resistance of the battery to be tested to be basically in the state of ohmic internal resistance and electrochemical internal resistance.

[0015] In one possible implementation, the battery to be tested is a lithium-ion battery, and the measurement method further includes: determining a reference exchange current density of the battery to be tested based on the exchange current density of the battery to be tested and material parameters of the battery to be tested, the material parameters including lithium ion concentration of active material particles, reference lithium ion concentration of active material particles, maximum lithium ion concentration of active material particles, lithium ion concentration of electrolyte, reference lithium ion concentration of electrolyte, anode transfer coefficient, and cathode transfer coefficient.

[0016] By adopting the above technical solution, after determining the exchange current density of the battery in the discharge state, the reference exchange current density of the battery in the discharge state can be further determined, so as to meet the needs of some battery design analysis or battery simulation testing that require reference to the exchange current density.

[0017] In a possible implementation, the battery to be tested includes a positive electrode, a negative electrode and a reference electrode. If the voltage change value is the voltage change value of the voltage between the positive electrode and the reference electrode within a preset discharge time, the internal resistance of the battery to be tested is determined based on the voltage change value and the preset pulse current, including: determining the first internal resistance of the battery to be tested based on the voltage change value of the voltage between the positive electrode and the reference electrode within the preset discharge time and the preset pulse current; determining the exchange current density of the battery to be tested based on the electrode effective reaction area, the internal resistance of the battery to be tested and the temperature of the preset environment, including: determining the positive electrode exchange current density of the battery to be tested based on the positive electrode effective reaction area, the first internal resistance of the battery to be tested and the temperature of the preset environment; If the voltage change value is the voltage change value of the voltage between the negative electrode and the reference electrode within the preset discharge time, the internal resistance of the battery to be tested is determined based on the voltage change value and the preset pulse current, including: determining the second internal resistance of the battery to be tested based on the voltage change value of the voltage between the negative electrode and the reference electrode within the preset discharge time and the preset pulse current; determining the exchange current density of the battery to be tested based on the electrode effective reaction area, the internal resistance of the battery to be tested and the temperature of the preset environment, including: determining the negative electrode exchange current density of the battery to be tested based on the negative electrode effective reaction area, the second internal resistance of the battery to be tested and the temperature of the preset environment.

[0018] By adopting the above technical scheme, the exchange current density of the positive electrode and the negative electrode can be decoupled, that is, the positive electrode exchange current density of the battery to be tested and the negative electrode exchange current density of the battery to be tested can be measured separately, so as to facilitate the analysis of the positive electrode exchange current density and the negative electrode exchange current density, or meet some needs that require the positive electrode exchange current density / negative electrode exchange current density for battery design analysis or battery simulation testing.

[0019] In a second aspect, the present application provides a method for measuring battery exchange current density, comprising: charging a battery to be tested in a preset environment with a preset pulse current; obtaining a voltage change value of the battery to be tested within a preset charging time; determining an internal resistance of the battery to be tested based on the voltage change value and the preset pulse current; obtaining an effective reaction area of ​​an electrode of the battery to be tested; and determining the exchange current density of the battery to be tested based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested, and the temperature of the preset environment.

[0020] By adopting the above technical scheme, the internal resistance of the battery to be tested is quickly calculated based on the voltage rise caused by the ohmic polarization and electrochemical polarization of the battery under the specified charging current and the corresponding preset pulse current. Then, based on the internal resistance of the battery to be tested, the measured ambient temperature and the effective reaction area of ​​the electrode, the exchange current density of the battery to be tested at the ambient temperature can be quickly determined. The measurement takes a short time, is simple and low in cost, and has high accuracy, and can monitor the exchange current density of the battery in the charging state in real time.

[0021] In a third aspect, the present application provides a device for measuring battery exchange current density, including: a charge and discharge control module, used to discharge a battery to be tested in a preset environment with a preset pulse current, or to charge a battery to be tested with a preset pulse current; a first acquisition module, used to obtain a first voltage change value of the battery to be tested within a preset discharge time, or to obtain a second voltage change value of the battery to be tested within a preset charging time; a first determination module, used to determine a first internal resistance of the battery to be tested based on the first voltage change value and the preset pulse current, or to determine a second internal resistance of the battery to be tested based on the second voltage change value and the preset pulse current; a second acquisition module, used to obtain an effective reaction area of ​​an electrode of the battery to be tested; a second determination module, used to determine the exchange current density of the battery to be tested in a discharge state based on the effective reaction area of ​​the electrode, the first internal resistance of the battery to be tested, and the temperature of the preset environment, or to determine the exchange current density of the battery to be tested in a charging state based on the effective reaction area of ​​the electrode, the second internal resistance of the battery to be tested, and the temperature of the preset environment.

[0022] In a fourth aspect, the present application provides a computer device, which includes a memory and a processor; the memory and the processor are coupled; the memory is used to store program instructions; the processor is used to read the program instructions stored in the memory, so as to implement the battery exchange current density measurement method of the above-mentioned first aspect and its possible implementation methods, or to implement the battery exchange current density measurement method of the above-mentioned second aspect.

[0023] In a fifth aspect, the present application provides a computer-readable storage medium, in which computer-readable instructions are stored. When the computer-readable instructions are executed by a processor, the method for measuring the battery exchange current density of the first aspect and its possible implementation methods is implemented, or the method for measuring the battery exchange current density of the second aspect is implemented.

[0024] In addition, the technical effects brought about by the third to fifth aspects can be found in the descriptions related to the methods of each design in the above method part, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a possible application scenario provided by an embodiment of the present application; Figure 2 A flowchart of a method for measuring battery exchange current density provided in one embodiment of the present application; Figure 3 A comparison diagram of a battery voltage simulation curve obtained by using an electrochemical mechanism model and an actual test curve of the battery voltage, obtained by using the exchange current density measured in one embodiment of the present application; Figure 4 A flowchart of a method for measuring battery exchange current density provided in another embodiment of the present application; Figure 5 A flowchart of a method for measuring battery exchange current density provided in another embodiment of the present application; Figure 6 A flowchart of a method for measuring battery exchange current density provided in another embodiment of the present application; Figure 7 A flowchart of a method for measuring battery exchange current density provided in another embodiment of the present application; Figure 8 A schematic diagram of functional modules of a device for measuring battery exchange current density provided in one embodiment of the present application; Fig. 9 A hardware architecture diagram of a computer device provided in accordance with an embodiment of the present application. DETAILED DESCRIPTION

[0026] The following will describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0027] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, words such as "exemplary", "or", "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "or", "for example" is intended to present related concepts in a concrete way.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by technicians in the technical field of the present application. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. It should be understood that, unless otherwise specified in the present application, " / " means or. For example, A / B can represent A or B. "And / or" in the present application is only a kind of association relationship describing associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. "At least one" means one or more. "Multiple" means two or more than two. For example, at least one of a, b or c can represent: a, b, c, a and b, a and c, b and c, a, b and c seven situations. It should be understood that the order of the steps shown in the flowchart of this article can be changed, and some can also be omitted.

[0029] Exchange current density can be used as one of the performance indicators for evaluating batteries, and can be used to describe the ability of electrode materials in batteries to gain or lose electrons. The greater the exchange current density, the stronger the ability to participate in the redox reaction current, and the better the electrochemical reversibility during the charge and discharge process. Conversely, the weaker the ability to participate in the redox reaction current, the worse the electrochemical reversibility during the charge and discharge process. At present, the measurement process of exchange current density is relatively complicated, and it is impossible to measure the exchange current density of the battery in the charging or discharging state separately.

[0030] In view of this, an embodiment of the present application provides a method for measuring the exchange current density of a battery, which can measure the exchange current density of the battery in a charging or discharging state, and the measurement process is simple and highly accurate.

[0031] like Figure 1 As shown, a possible application scenario provided by an embodiment of the present application includes a computer device 100, a charging and discharging device 200, and a battery to be tested 300. The computer device 100 can be a computing device such as a computer or a server, or a portable smart device such as a mobile phone or a tablet computer. The embodiment of the present application does not limit the device type of the computer device 100. The charging and discharging device 200 is used to charge or discharge the battery to be tested 300.

[0032] For example, the charge and discharge device 200 may perform pulse charging or pulse discharging of the battery 300 under test at a specified rate in response to the instruction of the computer device 100. The charge and discharge device 200 may also collect the voltage rise or voltage drop of the battery 300 under test. Then, the computer device 100 may determine the internal resistance of the battery 300 under test based on the voltage rise or voltage drop collected by the charge and discharge device 200, so as to determine the exchange current density of the battery 300 under test based on the internal resistance of the battery 300 under test and the effective reaction area of ​​the electrode.

[0033] For example, the charging and discharging device 200 may include a related voltage acquisition module to acquire the voltage rise or voltage drop of the battery 300 to be tested.

[0034] In some embodiments, the computer device 100 and the charging and discharging device 200 may also be integrated into one device, which is not limited in the embodiments of the present application.

[0035] See also Figure 2 , Figure 2 A flow chart of a method for measuring battery exchange current density provided in one embodiment of the present application is provided. The method for measuring battery exchange current density can be applied to the above-mentioned computer device, and the method for measuring battery exchange current density can include the following steps.

[0036] S201, discharging a battery to be tested in a preset environment with a preset pulse current.

[0037] In some embodiments, the preset environment may refer to a test environment set up for measuring the exchange current density. For example, the preset environment may be a constant temperature test environment, and the temperature of the test environment may be set according to actual test requirements, which is not limited in the embodiments of the present application. For example, the preset environment may be a constant temperature incubator at 25 degrees, and the battery to be tested is placed in the constant temperature incubator to measure the exchange current density.

[0038] The battery to be tested may be a lithium-ion battery, or other batteries that can be cyclically charged and discharged. The following description is made by taking the battery to be tested as a lithium-ion battery as an example. The present application does not limit the packaging type of the battery to be tested. For example, the battery to be tested may be a button battery, a cylindrical packaged battery, a soft-pack packaged battery, or a square packaged battery.

[0039] In some embodiments, the battery to be tested for discharge with a preset pulse current may include multiple packaging types, and then the measurement method of the embodiment of the present application may be used to measure the exchange current density of the battery to be tested of each packaging type, respectively, so as to facilitate the evaluation of the measurement compatibility of the measurement method of the embodiment of the present application for batteries of different packaging types. In other embodiments, the battery to be tested for discharge with a preset pulse current may include multiple battery types, so as to facilitate the evaluation of the measurement compatibility of the measurement method of the embodiment of the present application for batteries of different types.

[0040] For example, multiple packaging types of batteries to be tested can be obtained in the following ways: a. Use pole pieces, lithium metal, electrolyte, etc. to make button batteries, soft-pack packaged batteries, and square packaged batteries; perform formation, aging, and capacity separation on the button batteries, soft-pack packaged batteries, and square packaged batteries; according to the capacity separation results, adjust the button batteries, soft-pack packaged batteries, and square packaged batteries to a preset SOC through charge and discharge. The button batteries, soft-pack packaged batteries, and square packaged batteries adjusted to the preset SOC can be placed in preset environments respectively to measure the exchange current density in turn.

[0041] If the charging and discharging equipment supports the discharge of preset pulse current and the collection of voltage drop for multiple battery pulses to be tested, button cells, soft-pack packaged batteries and square packaged batteries adjusted to the preset SOC can also be placed in the preset environment at the same time to measure the exchange current density in parallel.

[0042] In some embodiments, for the button cells, soft-pack packaged batteries and square packaged batteries produced by step a, after formation and aging, the SOCs of the button cells, soft-pack packaged batteries and square packaged batteries may be different. In order to adjust the SOCs of the button cells, soft-pack packaged batteries and square packaged batteries to the preset SOCs, the button cells, soft-pack packaged batteries and square packaged batteries after formation and aging can be divided into different capacities, and according to the current SOC of each battery, the charging or discharging method can be selected to adjust them to the preset SOC.

[0043] In some embodiments, in order to reduce the impact of formation on battery performance, the maximum formation rate of button batteries can be set within 0.1C, and the maximum formation rate of soft-pack packaged batteries and square packaged batteries can be set within 0.33C. The preset SOC can be set according to actual test requirements, and the embodiments of the present application are not limited to this. For example, the preset SOC can be set between 0 and 1.

[0044] In some embodiments, the discharge of the preset pulse current may refer to a constant current discharge performed within a preset pulse time. For example, the preset pulse time may be 2s or more, and the discharge rate may be 2C or more.

[0045] In some embodiments, the charging and discharging device may be a constant current charging and discharging test cabinet, and the computer device may control the constant current charging and discharging test cabinet to discharge a battery to be tested in a preset environment with a preset pulse current.

[0046] S202, obtaining a voltage change value of the battery to be tested within a preset discharge time.

[0047] In some embodiments, the preset discharge time can be set according to actual test requirements, and the embodiments of the present application do not limit this. For example, the preset discharge time is to make the internal resistance of the battery basically in the state of ohmic internal resistance and electrochemical internal resistance, so that the internal resistance of the battery to be tested can be determined based on the voltage change value and the discharge current. For another example, the preset discharge time can be 1s when the preset pulse current is used to start the discharge timing of the battery to be tested, that is, the resistance value at the 1st second of discharge is taken as the internal resistance of the battery to be tested.

[0048] Taking the preset discharge time of 1 second for starting discharge timing of the battery to be tested using a preset pulse current as an example, the voltage acquisition module can collect the voltage value of the battery to be tested before discharge and the voltage value after 1 second of discharge to obtain the voltage drop (voltage change value). The voltage acquisition module can transmit the collected voltage value to the computer device, and then the computer device can calculate the voltage change value of the battery to be tested in the first second of discharge.

[0049] S203, determining the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current.

[0050] In some embodiments, after obtaining the voltage change value of the battery to be tested, the computer device can determine the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current. For example, the discharge rate is 2C, that is, the current value of the preset pulse current is 2C, and the internal resistance of the battery to be tested = voltage change value / 2C.

[0051] In some embodiments, it is verified through experiments that the internal resistance calculated based on the voltage drop / voltage rise caused by the ohmic polarization and electrochemical polarization of the battery under large current and the corresponding preset pulse current has only a slight error (less than 7%) with the sum of the ohmic impedance, membrane resistance, and charge transfer impedance fitted by the AC impedance spectrum obtained by the AC impedance method test. That is, the method of measuring the internal resistance of the battery to be tested in the embodiment of the present application has a simple test method and can obtain a more accurate internal resistance measurement result.

[0052] S204, obtaining the effective reaction area of ​​the electrode of the battery to be tested.

[0053] In some embodiments, the electrode effective reaction area can be determined by the relevant parameters of the pole piece and the active material particles used in the battery to be tested. For example, the electrode effective reaction area can be determined based on the surface area of ​​the active material particles and the pole piece porosity by obtaining the surface area of ​​the active material particles coated on the pole piece of the battery to be tested and the pole piece porosity.

[0054] In some embodiments, the effective reaction area of ​​the electrode of the battery to be tested can be determined by the following formula: A = A' × ε s =[(3ρ s ×A0) / (ρ0×r)]×εs ; Among them, A is the effective reaction area of ​​the electrode, A' is the surface area of ​​the active material particles coated on the electrode, and ε s is the electrode porosity, ρ s is the surface density of the electrode, A0 is the area of ​​the electrode, ρ0 is the true density of the active material, and r is the radius of the active material particle. The electrode effective reaction area can be the sum of the positive electrode effective reaction area and the negative electrode effective reaction area.

[0055] S205, determining the exchange current density of the battery to be tested based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested, and the temperature of the preset environment.

[0056] After obtaining the electrode effective reaction area and the internal resistance of the battery to be tested, the computer device can determine the exchange current density of the battery to be tested at the temperature based on the electrode effective reaction area, the internal resistance of the battery to be tested and the temperature of the preset environment.

[0057] In some embodiments, the exchange current density of the battery to be tested can be determined based on the following formula: i0=(R×T) / (A×F×R t ), Among them, i0 is the exchange current density of the battery to be tested, R is the gas constant, T is the temperature of the preset environment, A is the effective reaction area of ​​the electrode, F is the Faraday constant, and R t is the internal resistance of the battery to be tested.

[0058] The above calculation formula for the exchange current density is an example. The above calculation formula for calculating the exchange current density of the battery to be tested can be appropriately modified according to actual measurement requirements to calculate the exchange current density of the battery to be tested.

[0059] It can be understood that when it is necessary to measure the exchange current density of the battery to be tested discharged at different temperatures, the exchange current density of the battery to be tested discharged at a specified temperature can be determined by changing the temperature of the preset environment based on the internal resistance measured by the above method and the obtained electrode effective reaction area and temperature.

[0060] like Figure 3 , which is a comparison diagram of a battery voltage simulation curve obtained by using the exchange current density obtained by the measurement method of the present application for electrochemical mechanism model calculation and an actual battery voltage test curve.

[0061] exist Figure 3 In (a), curve S11 corresponds to the battery voltage simulation curve obtained by using the exchange current density obtained by the measurement method of the present application for the electrochemical mechanism model calculation, and curve S12 corresponds to the actual test curve of the battery voltage. Figure 3It can be seen from (a) in that at a charging rate of 0.33C, the curves of the battery voltages of the two devices over time are basically the same, and the root mean square error of the battery voltages of the two devices is about 27.7mV, which is a small difference. Figure 3 In (b), curve S21 corresponds to the battery voltage simulation curve obtained by using the exchange current density obtained by the measurement method of the present application for the electrochemical mechanism model calculation, and curve S22 corresponds to the actual test curve of the battery voltage. Figure 3 As can be seen from (b) in the figure, at a charging rate of 1C, the curves of the battery voltages of the two batteries over time are basically the same, and the root mean square error of the battery voltages of the two batteries is about 24.4mV, which is also a small difference. That is, the exchange current density obtained by the measurement method of the present application is basically equivalent to the actual exchange current density, and the exchange current density obtained by the measurement method of the present application is highly accurate.

[0062] The above-mentioned method for measuring the battery exchange current density quickly calculates the internal resistance of the battery to be tested based on the voltage drop caused by the ohmic polarization and electrochemical polarization of the battery under a large discharge current and the corresponding preset pulse current, and then based on the internal resistance of the battery to be tested, the measurement ambient temperature and the effective reaction area of ​​the electrode, the exchange current density of the battery to be tested discharged at the ambient temperature can be quickly determined. The measurement is short in time, low in cost (only relatively common measuring equipment is required), and highly accurate, and real-time monitoring of the exchange current density of the battery in the discharge state can be achieved.

[0063] See also Figure 4 , Figure 4 A flow chart of a method for measuring battery exchange current density provided in another embodiment of the present application. The method for measuring battery exchange current density can be applied to the above-mentioned computer device, and Figure 2 compared to, Figure 4 The measurement method shown is used to measure the reference exchange current density of the battery to be tested when it is discharged at a specified temperature. The measurement method of the battery exchange current density may include the following steps.

[0064] S401, discharging a battery to be tested in a preset environment with a preset pulse current.

[0065] Step S401 of the embodiment of the present application is similar to step S201 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0066] S402, obtaining a voltage change value of the battery to be tested within a preset discharge time.

[0067] Step S402 of the embodiment of the present application is similar to step S202 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0068] S403, determining the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current.

[0069] Step S403 of the embodiment of the present application is similar to step S203 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0070] S404, obtaining the effective reaction area of ​​the electrode of the battery to be tested.

[0071] Step S404 of the embodiment of the present application is similar to step S204 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0072] S405, determining the exchange current density of the battery to be tested based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested, and the temperature of the preset environment.

[0073] Step S405 of the embodiment of the present application is similar to step S205 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0074] S406, determining a reference exchange current density of the battery to be tested based on the exchange current density of the battery to be tested and material parameters of the battery to be tested.

[0075] In some embodiments, the material parameters of the battery to be tested may include the lithium ion concentration of the active material particles, the reference lithium ion concentration of the active material particles, the maximum lithium ion concentration of the active material particles, the lithium ion concentration of the electrolyte, the reference lithium ion concentration of the electrolyte, the anode transfer coefficient, and the cathode transfer coefficient.

[0076] In some embodiments, the conversion formula between the exchange current density of the battery to be tested and the reference exchange current density is as follows: Among them, i0 is the exchange current density of the battery to be tested, i 0,ref is the reference exchange current density of the battery to be tested, C s is the lithium ion concentration of active material particles, C s,ref is the reference lithium ion concentration of active material particles, C s,max is the maximum lithium ion concentration of active material particles, C l is the lithium ion concentration of the electrolyte, C l,ref is the reference lithium ion concentration of the electrolyte, α a is the positive electrode transfer coefficient, α c is the negative electrode transfer coefficient.

[0077] The above-mentioned battery exchange current density measurement method can further determine the reference exchange current density of the battery in the discharge state after determining the exchange current density of the battery in the discharge state, so as to meet the needs of some battery design analysis or battery simulation testing that require reference to the exchange current density.

[0078] See also Figure 5 , Figure 5 A flow chart of a method for measuring battery exchange current density provided in another embodiment of the present application. The method for measuring battery exchange current density can be applied to the above-mentioned computer device, and Figure 2 compared to, Figure 5 The measurement method shown is used to measure the exchange current density of a battery under test when it is charged at a specified temperature. The measurement method of the battery exchange current density may include the following steps.

[0079] S501, charging a battery to be tested in a preset environment with a preset pulse current.

[0080] In some embodiments, charging with a preset pulse current may refer to constant current charging performed within a preset pulse time. For example, the preset pulse time may be 2s or more, and the charging rate may be 2C or more.

[0081] In some embodiments, the charging and discharging device may be a constant current charging and discharging test cabinet, and the computer device may control the constant current charging and discharging test cabinet to charge the battery to be tested in a preset environment with a preset pulse current.

[0082] S502, obtaining a voltage change value of the battery to be tested within a preset charging time.

[0083] In some embodiments, the preset charging time can be set according to actual test requirements, which is not limited in the embodiments of the present application. For example, the preset charging time is to make the internal resistance of the battery basically in the state of ohmic internal resistance and electrochemical internal resistance, so that the internal resistance of the battery to be tested can be determined based on the voltage change value and the charging current. For another example, the preset charging time can be 1 second when the preset pulse current is used to start charging the battery to be tested, that is, the resistance value at the first second of charging is taken as the internal resistance of the battery to be tested.

[0084] Taking the preset charging time of 1 second for starting charging timing of the battery to be tested using a preset pulse current as an example, the voltage acquisition module can collect the voltage value of the battery to be tested before charging and the voltage value after charging for 1 second to obtain the voltage rise (voltage change value). The voltage acquisition module can transmit the collected voltage value to the computer device, and then the computer device can calculate the voltage change value of the battery to be tested in the first second of charging.

[0085] S503, determining the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current.

[0086] Step S503 of the embodiment of the present application is similar to step S203 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0087] S504, obtaining the effective reaction area of ​​the electrode of the battery to be tested.

[0088] Step S504 of the embodiment of the present application is similar to step S204 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0089] S505, determining the exchange current density of the battery to be tested based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested, and the temperature of the preset environment.

[0090] After obtaining the electrode effective reaction area and the internal resistance of the battery to be tested, the computer device can determine the exchange current density of the battery to be tested at the temperature based on the electrode effective reaction area, the internal resistance of the battery to be tested and the temperature of the preset environment. The calculation formula for the exchange current density charged at the specified temperature can refer to the formula mentioned in step S205 of the above embodiment, and will not be repeated here to avoid repetition.

[0091] It can be understood that when it is necessary to measure the exchange current density of the battery to be tested when charged at different temperatures, the exchange current density of the battery to be tested when charged at a specified temperature can be determined by changing the temperature of the preset environment based on the internal resistance measured by the above method and the obtained electrode effective reaction area and temperature.

[0092] It is understandable that when it is necessary to measure the reference exchange current density of the battery under test when charged at different temperatures, the reference exchange current density can also be converted using the formula mentioned in step S406 of the aforementioned embodiment. To avoid repetition, it will not be described here.

[0093] The above-mentioned battery exchange current density measurement method is based on the voltage rise caused by the battery ohmic polarization and electrochemical polarization under a large charging current and the corresponding preset pulse current to quickly calculate the internal resistance of the battery to be tested, and then based on the internal resistance of the battery to be tested, the measurement environment temperature and the effective reaction area of ​​the electrode, the exchange current density of the battery to be tested at the ambient temperature can be quickly determined. The measurement takes a short time, is low in cost, and has high accuracy, and can monitor the exchange current density of the battery in the charging state in real time. Furthermore, the exchange current density of charging and discharging at a specified temperature is measured respectively by the above-mentioned battery exchange current density measurement method. By comparing and analyzing the exchange current density of charging and discharging, it is convenient to evaluate the design of the battery, material selection and other aspects.

[0094] In some embodiments, the exchange current density measured by the above-mentioned measurement method of the present application represents the exchange current density between the positive and negative electrodes. If the battery to be tested includes three electrodes: a positive electrode, a negative electrode, and a reference electrode. The present application can also achieve decoupling of the exchange current density of the positive electrode and the negative electrode through the following embodiments, that is, measuring the exchange current density of the positive electrode of the battery to be tested and the exchange current density of the negative electrode of the battery to be tested.

[0095] See also Figure 6 , Figure 6 A flow chart of a method for measuring battery exchange current density provided in another embodiment of the present application. The method for measuring battery exchange current density can be applied to the above-mentioned computer device, and Figure 2 compared to, Figure 6 The measurement method shown is used to measure the positive electrode exchange current density of the battery to be tested when discharged at a specified temperature. The battery exchange current density measurement method may include the following steps.

[0096] S601, discharging a battery to be tested in a preset environment with a preset pulse current.

[0097] Step S601 of the embodiment of the present application is similar to step S201 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0098] S602, obtaining a voltage change value between a positive electrode and a reference electrode of the battery to be tested within a preset discharge time.

[0099] Taking the preset discharge time of 1 second for starting discharge timing of the battery to be tested using a preset pulse current as an example, the voltage acquisition module can collect the voltage value of the positive electrode of the battery to be tested relative to the reference electrode before discharge and the voltage value of the positive electrode relative to the reference electrode after 1 second of discharge to obtain the voltage change value. The voltage acquisition module can transmit the collected voltage value to the computer device, and then the computer device can calculate the voltage change value between the positive electrode and the reference electrode of the battery to be tested in the 1st second of discharge.

[0100] S603, determining a first internal resistance of the battery to be tested based on the voltage change value and the preset pulse current.

[0101] Step S603 of the embodiment of the present application is similar to step S203 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0102] S604, obtaining the effective reaction area of ​​the positive electrode of the battery to be tested.

[0103] In some embodiments, the positive electrode effective reaction area may be calculated based on the calculation formula of the electrode effective reaction area mentioned in step S204 of the aforementioned embodiment, which will not be described again here to avoid repetition.

[0104] S605, determining the positive electrode exchange current density of the battery to be tested based on the positive electrode effective reaction area, the first internal resistance of the battery to be tested, and the temperature of the preset environment.

[0105] In some embodiments, the positive electrode exchange current density may be calculated based on the calculation formula for the exchange current density mentioned in step S205 of the aforementioned embodiment, which will not be described again here to avoid repetition.

[0106] It is understandable that the positive electrode exchange current density of the battery under test at a specified temperature can be measured by charging the battery under test in a preset environment with a preset pulse current, with reference to the above steps S602 to S605.

[0107] See also Figure 7 , Figure 7 A flow chart of a method for measuring battery exchange current density provided in another embodiment of the present application. The method for measuring battery exchange current density can be applied to the above-mentioned computer device, and Figure 2 compared to, Figure 7 The measurement method shown is used to measure the negative electrode exchange current density of the battery to be tested when discharged at a specified temperature. The battery exchange current density measurement method may include the following steps.

[0108] S701, discharging a battery to be tested in a preset environment with a preset pulse current.

[0109] Step S701 of the embodiment of the present application is similar to step S201 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0110] S702, obtaining a voltage change value between a negative electrode and a reference electrode of the battery to be tested within a preset discharge time.

[0111] Taking the preset discharge time of 1 second for starting discharge timing of the battery to be tested using a preset pulse current as an example, the voltage acquisition module can collect the voltage value of the negative electrode of the battery to be tested relative to the reference electrode before discharge and the voltage value of the negative electrode relative to the reference electrode after 1 second of discharge to obtain the voltage change value. The voltage acquisition module can transmit the collected voltage value to the computer device, and then the computer device can calculate the voltage change value between the negative electrode and the reference electrode of the battery to be tested in the 1st second of discharge.

[0112] S703, determining a second internal resistance of the battery to be tested based on the voltage change value and the preset pulse current.

[0113] Step S703 of the embodiment of the present application is similar to step S203 of the aforementioned embodiment, and will not be described again here to avoid repetition.

[0114] S704, obtaining the effective reaction area of ​​the negative electrode of the battery to be tested.

[0115] In some embodiments, the negative electrode effective reaction area may be calculated based on the calculation formula for the electrode effective reaction area mentioned in step S204 of the aforementioned embodiment, which will not be described again here to avoid repetition.

[0116] S705 , determining the negative electrode exchange current density of the battery to be tested based on the negative electrode effective reaction area, the second internal resistance of the battery to be tested, and the temperature of the preset environment.

[0117] In some embodiments, the negative electrode exchange current density may be calculated based on the calculation formula for the exchange current density mentioned in step S205 of the aforementioned embodiment, which will not be described again here to avoid repetition.

[0118] It is understandable that the negative electrode exchange current density of the battery under test at a specified temperature can be measured by charging the battery under test in a preset environment with a preset pulse current, with reference to the above steps S702 to S705.

[0119] Please refer to Figure 8 , which is a functional module diagram of a battery exchange current density measurement device provided in an embodiment of the present application. The measurement device 80 includes a charge and discharge control module 801, a first acquisition module 802, a first determination module 803, a second acquisition module 804 and a second determination module 805. In some embodiments, the above modules may be programmable software instructions stored in a memory and can be called and executed by a processor. It is understood that in other embodiments, the above modules may also be program instructions or firmware solidified in the processor.

[0120] When the exchange current density of the battery to be tested in the discharge state is measured by the measuring device 80, the functions of the charge and discharge control module 801, the first acquisition module 802, the first determination module 803, the second acquisition module 804 and the second determination module 805 are as follows: The charge and discharge control module 801 is used to discharge the battery to be tested in a preset environment with a preset pulse current.

[0121] The first acquisition module 802 is used to acquire a voltage change value of the battery to be tested within a preset discharge time.

[0122] The first determination module 803 is used to determine the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current.

[0123] The second acquisition module 804 is used to acquire the effective reaction area of ​​the electrode of the battery to be tested.

[0124] The second determination module 805 is used to determine the exchange current density of the battery to be tested in the discharge state based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested and the temperature of the preset environment.

[0125] When the exchange current density of the battery under test in the charging state is measured by the measuring device 80, the functions of the charge and discharge control module 801, the first acquisition module 802, the first determination module 803, the second acquisition module 804 and the second determination module 805 are as follows: The charge and discharge control module 801 is used to charge the battery to be tested in a preset environment with a preset pulse current.

[0126] The first acquisition module 802 is used to acquire a voltage change value of the battery to be tested within a preset charging time.

[0127] The first determination module 803 is used to determine the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current.

[0128] The second acquisition module 804 is used to acquire the effective reaction area of ​​the electrode of the battery to be tested.

[0129] The second determination module 805 is used to determine the exchange current density of the battery to be tested in a charging state based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested and the temperature of a preset environment.

[0130] Please refer to Fig. 9 , is a schematic diagram of the hardware structure of the computer device 100 provided in the embodiment of the present application. Fig. 9 As shown, the computer device 100 may include a processor 1001 and a memory 1002. The memory 1002 is used to store one or more computer programs 1003. The one or more computer programs 1003 are configured to be executed by the processor 1001. The one or more computer programs 1003 include instructions, and the above instructions can be used to implement the above-mentioned battery exchange current density measurement method in the computer device 100.

[0131] It is understandable that the structure shown in this embodiment does not constitute a specific limitation on the computer device 100. In other embodiments, the computer device 100 may include more or fewer components than shown, or combine or separate some components, or arrange the components differently.

[0132] The processor 1001 may include one or more processing units, for example, the processor 1001 may include an application processor (AP), a modem, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU), etc. Different processing units may be independent devices or integrated into one or more processors.

[0133] The processor 1001 may also be provided with a memory for storing instructions and data. In some embodiments, the memory in the processor 1001 is a cache memory. The memory may store instructions or data that the processor 1001 has just used or circulated. If the processor 1001 needs to use the instruction or data again, it may be directly called from the memory. This avoids repeated access, reduces the waiting time of the processor 1001, and thus improves the efficiency of the system.

[0134] In some embodiments, the processor 1001 may include one or more interfaces. The interface may include an inter-integrated circuit (I2C) interface, an inter-integrated circuit sound (I2S) interface, a pulse code modulation (PCM) interface, a universal asynchronous receiver / transmitter (UART) interface, a mobile industry processor interface (MIPI), a general-purpose input / output (GPIO) interface, a SIM interface, and / or a USB interface, etc.

[0135] In some embodiments, memory 1002 may include high-speed random access memory and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0136] The battery exchange current density measurement methods in the above embodiments can all be implemented in the computer device 100 having the above hardware structure.

[0137] This embodiment also provides a computer-readable storage medium, which stores computer instructions. When the computer instructions are executed on the computer device 100, the computer device 100 executes the above-mentioned related method steps to implement the battery exchange current density measurement method in the above-mentioned embodiment.

[0138] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0139] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0140] The unit described as a separate component may or may not be physically separated, and the component shown as a unit may be one physical unit or multiple physical units, that is, it may be located in one place or distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment.

[0141] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0142] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to execute all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program code.

[0143] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for measuring battery exchange current density, characterized in that: The method comprises: Discharging the battery to be tested in a preset environment with a preset pulse current; Obtaining a voltage change value of the battery to be tested within a preset discharge time; Determining the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current; Obtaining the effective reaction area of ​​the electrode of the battery to be tested; The exchange current density of the battery to be tested is determined based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested, and the temperature of the preset environment.

2. The measuring method according to claim 1, characterized in that: The exchange current density of the battery to be tested is determined based on the following formula: i0=(R×T) / (A×F×R t ), Among them, i0 is the exchange current density of the battery to be tested, R is the gas constant, T is the temperature of the preset environment, A is the effective reaction area of ​​the electrode, F is the Faraday constant, and R t is the internal resistance of the battery to be tested.

3. The measuring method according to claim 1, characterized in that: The preset discharge time is 1 second from the start of discharging the battery to be tested using the preset pulse current.

4. The measuring method according to claim 1, characterized in that: The method further comprises: Obtaining the surface area of ​​the active material particles coated on the electrode of the battery to be tested and the electrode porosity; The effective reaction area of ​​the electrode is determined based on the surface area of ​​the active material particles and the porosity of the electrode sheet.

5. The measuring method according to any one of claims 1 to 4, characterized in that: The preset environment is a constant temperature environment in which the ambient temperature is a preset value, and the preset pulse current is greater than or equal to 2C.

6. The measuring method according to any one of claims 1 to 4, characterized in that: The battery to be tested is a lithium-ion battery, and the method further comprises: Based on the exchange current density of the battery to be tested and the material parameters of the battery to be tested, the reference exchange current density of the battery to be tested is determined, and the material parameters include the lithium ion concentration of active material particles, the reference lithium ion concentration of active material particles, the maximum lithium ion concentration of active material particles, the lithium ion concentration of the electrolyte, the reference lithium ion concentration of the electrolyte, the anode transfer coefficient and the cathode transfer coefficient.

7. The measuring method according to claim 1, characterized in that: The battery to be tested includes a positive electrode, a negative electrode, and a reference electrode. If the voltage change value is a voltage change value of the voltage between the positive electrode and the reference electrode within the preset discharge time, determining the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current includes: Determining a first internal resistance of the battery to be tested based on a voltage change value of a voltage between the positive electrode and the reference electrode within the preset discharge time and the preset pulse current; The step of determining the exchange current density of the battery to be tested based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested, and the temperature of the preset environment includes: Determining the positive electrode exchange current density of the battery to be tested based on the positive electrode effective reaction area, the first internal resistance of the battery to be tested, and the temperature of the preset environment; If the voltage change value is a voltage change value of the voltage between the negative electrode and the reference electrode within the preset discharge time, determining the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current includes: Determining a second internal resistance of the battery to be tested based on a voltage change value of a voltage between the negative electrode and the reference electrode within the preset discharge time and the preset pulse current; The step of determining the exchange current density of the battery to be tested based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested, and the temperature of the preset environment includes: The negative electrode exchange current density of the battery to be tested is determined based on the negative electrode effective reaction area, the second internal resistance of the battery to be tested, and the temperature of the preset environment.

8. A method for measuring battery exchange current density, characterized in that: The method comprises: Charging the battery to be tested in a preset environment with a preset pulse current; Obtaining a voltage change value of the battery to be tested within a preset charging time; Determining the internal resistance of the battery to be tested based on the voltage change value and the preset pulse current; Obtaining the effective reaction area of ​​the electrode of the battery to be tested; The exchange current density of the battery to be tested is determined based on the effective reaction area of ​​the electrode, the internal resistance of the battery to be tested, and the temperature of the preset environment.

9. A device for measuring battery exchange current density, characterized in that: The device comprises: A charge and discharge control module, used to discharge a battery to be tested in a preset environment with a preset pulse current, or to charge the battery with the preset pulse current; A first acquisition module, used to acquire a first voltage change value of the battery to be tested within a preset discharge time, or to acquire a second voltage change value of the battery to be tested within a preset charging time; A first determination module, configured to determine a first internal resistance of the battery to be tested based on the first voltage change value and the preset pulse current, or to determine a second internal resistance of the battery to be tested based on the second voltage change value and the preset pulse current; A second acquisition module, used to acquire the effective reaction area of ​​the electrode of the battery to be tested; The second determination module is used to determine the exchange current density of the battery to be tested in a discharge state based on the effective reaction area of ​​the electrode, the first internal resistance of the battery to be tested and the temperature of the preset environment, or to determine the exchange current density of the battery to be tested in a charge state based on the effective reaction area of ​​the electrode, the second internal resistance of the battery to be tested and the temperature of the preset environment.

10. A computer device, characterized in that: The computer device includes a memory and a processor; The memory is coupled to the processor; The memory is used to store program instructions; The processor is used to read the program instructions stored in the memory to implement the battery exchange current density measurement method as described in any one of claims 1 to 7, or to implement the battery exchange current density measurement method as described in claim 8.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the method for measuring the battery exchange current density as described in any one of claims 1 to 7 is implemented, or the method for measuring the battery exchange current density as described in claim 8 is implemented.

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