A method, system and device for determining factors affecting battery degradation

Abstract

The application discloses a kind of battery attenuation influence factor determination method, system and device, applied to battery test field, including to battery once constant current charging, constant voltage charging and constant current discharging;According to the total charging capacity of battery, constant voltage charging capacity, discharge capacity, total charging energy and discharge energy, determine the influence value of internal resistance change, the influence value of active lithium loss and total influence value;According to the influence value of internal resistance change, the influence value of active lithium loss and total influence value, determine the material polarization rate of battery, material polarization rate represents the influence value of material destruction.Due to the existence of three kinds of influences, the phenomenon of charging voltage rise will appear, the total influence value of three influence factors is determined by the process of constant voltage charging.Because internal resistance change and active lithium loss will affect the voltage of charging process, voltage is related to energy and capacity, so the influence value of internal resistance change and the influence value of active lithium loss are determined, and then the influence value of material destruction is determined, and the influence factor is positioned.

Description

Technical Field

[0001] This invention relates to the field of battery testing, and in particular to a method, system, and apparatus for determining factors affecting battery degradation. Background Technology

[0002] When studying high-energy and high-power-density lithium-ion battery systems, the problem of cycle failure is often encountered. In actual testing, when battery performance shows a significant decline during cycling—that is, when the remaining capacity drops below 80% of the initial value—the cell is considered essentially in a failed state. This is generally attributed to several factors: 1. Damage to the positive electrode material structure leading to cell failure; 2. Numerous side reactions hindering the electrochemical reaction; 3. Loss of active lithium. However, accurately analyzing the causes of accelerated battery capacity decay through electrochemical means remains a significant and challenging problem. Related technologies often employ non-in-situ characterization techniques to disassemble the battery; however, due to the influence of the external environment and instruments, errors are inevitably introduced into the characterization results, leading to erroneous analytical results and making it impossible to determine the main cause of cell degradation. Summary of the Invention

[0003] The purpose of this invention is to provide a method, system, and apparatus for determining the factors affecting battery degradation, thereby determining the impact values ​​of internal resistance changes and active lithium loss, and further determining the impact value of material damage, thus locating the influencing factors.

[0004] To address the aforementioned technical problems, this invention provides a method for determining the factors influencing battery degradation, comprising:

[0005] The battery is charged with a constant current using a first preset current;

[0006] When the voltage of the battery reaches a first preset voltage, the battery is charged at a constant voltage of the first preset voltage until the charging current of the battery reaches a second preset current, wherein the first preset current is greater than the second preset current.

[0007] The battery is discharged at a constant current with a third preset current until the voltage of the battery reaches a second preset voltage, where the second preset voltage is less than the first preset voltage.

[0008] The influence values ​​of internal resistance change, active lithium loss, and total influence value are determined based on the total charging capacity, constant voltage charging capacity, discharge capacity, total charging energy, and discharge energy of the battery. The total charging capacity is the sum of the constant voltage charging capacity and the constant current charging capacity.

[0009] The material polarization of the battery is determined based on the influence value of the internal resistance change, the influence value of the active lithium loss, and the total influence value. The material polarization characterizes the influence value of material damage.

[0010] On the other hand, the battery is charged with a constant current using a first preset current, including:

[0011] After the battery has been left to rest for a preset time, the battery is charged with a constant current using a first preset current.

[0012] On the other hand, before determining the impact values ​​of internal resistance change and active lithium loss based on the battery's total charging capacity, discharging capacity, total charging energy, and discharging energy, the process includes:

[0013] Based on the total charging capacity C1, the total charging energy W1, and the first relationship... Determine the average charging voltage V av.c ;

[0014] Based on the discharge capacity C2, the discharge energy W2, and the second relationship... Determine the average discharge voltage V av.d ;

[0015] The impact values ​​of internal resistance change and active lithium loss are determined based on the battery's total charging capacity, discharging capacity, total charging energy, and discharging energy, including:

[0016] The influence values ​​of internal resistance change and active lithium loss are determined based on the average charging voltage and the average discharging voltage.

[0017] On the other hand, determining the impact values ​​of internal resistance change and active lithium loss based on the average charging voltage and the average discharging voltage includes:

[0018] According to the third relation V av.c =R V +S V and the fourth relation V av.d =R V -S V Determine the effect voltage of the internal resistance change. and the effect voltage of the loss of active lithium.

[0019] The influence value of the internal resistance change is determined based on the voltage affected by the internal resistance change and the average charging voltage.

[0020] The impact value of active lithium loss is determined based on the voltage at which the active lithium loss occurs and the average discharge voltage.

[0021] On the other hand, the total influence value is determined based on the total charging capacity and constant voltage charging capacity of the battery, including:

[0022] The total influence value is determined based on the total charging capacity and the constant voltage charging capacity. Where Q is the constant voltage charging capacity.

[0023] On the other hand, determining the material polarization of the battery based on the influence value of the internal resistance change, the influence value of the active lithium loss, and the total influence value includes:

[0024] Based on the influence value of the internal resistance change, the influence value of the active lithium loss, the total influence value, and the fifth relationship... Determine the material polarizability Z of the battery.

[0025] On the other hand, before the battery is charged with a constant current using a first preset current, the following steps are also included:

[0026] Clear the counter;

[0027] After the battery is subjected to constant current discharge at a third preset current until the battery voltage reaches a second preset voltage, the process further includes:

[0028] Increment the counter by one and determine whether the preset number N has been reached;

[0029] If the target is not met, the process returns to the step of charging the battery with a first preset current after a preset time.

[0030] If the target is reached, then the material polarization of the battery for the Nth time is calculated.

[0031] On the other hand, after determining the material polarization of the battery based on the influence value of the internal resistance change, the influence value of the active lithium loss, and the total influence value, the method further includes:

[0032] Determine the material polarization of the battery after the first constant current discharge and the material polarization of the battery after the Nth constant current discharge;

[0033] The difference between the material polarizability of the battery after the Nth constant current discharge and the material polarizability of the battery after the first constant current discharge is determined, and the difference is negatively correlated with the structural stability of the battery material.

[0034] To address the aforementioned technical problems, the present invention also provides a system for determining the influencing factors of battery degradation, comprising:

[0035] A constant current charging unit is used to charge the battery with a first preset current at a constant current.

[0036] A constant voltage charging unit is used to charge the battery at a constant voltage of the first preset voltage when the voltage of the battery reaches the first preset voltage, until the charging current of the battery reaches the second preset current, wherein the first preset current is greater than the second preset current.

[0037] A constant current discharge unit is used to discharge the battery with a third preset current until the voltage of the battery reaches a second preset voltage, wherein the second preset voltage is less than the first preset voltage.

[0038] The influence value determination unit is used to determine the influence value of internal resistance change, the influence value of active lithium loss, and the total influence value based on the total charging capacity, constant voltage charging capacity, discharge capacity, total charging energy, and discharge energy of the battery. The total charging capacity is the sum of constant voltage charging capacity and constant current charging capacity.

[0039] A polarizability determination unit is used to determine the material polarizability of the battery based on the influence value of the internal resistance change, the influence value of the active lithium loss, and the total influence value, wherein the material polarizability characterizes the influence value of material damage.

[0040] To address the aforementioned technical problems, the present invention also provides an apparatus for determining the factors influencing battery degradation, comprising:

[0041] Memory, used to store computer programs;

[0042] A processor, used to execute the computer program to implement the steps of the method for determining factors affecting battery degradation as described above.

[0043] This application provides a method, system, and apparatus for determining factors affecting battery degradation, applied in the field of battery testing. The method includes performing constant current charging, constant voltage charging, and constant current discharging on the battery. Based on the battery's total charging capacity, constant voltage charging capacity, discharge capacity, total charging energy, and discharge energy, the method determines the influence values ​​of internal resistance change, active lithium loss, and the total influence value. Based on the influence values ​​of internal resistance change, active lithium loss, and the total influence value, the method determines the battery's material polarization, which characterizes the influence value of material damage. Due to the presence of these three influences, a voltage increase occurs. The total influence value of the three influencing factors is determined through the constant voltage charging process. Since both internal resistance change and active lithium loss affect the voltage during the charging process, and voltage is related to energy and capacity, the influence values ​​of internal resistance change and active lithium loss are determined, thereby determining the influence value of material damage and pinpointing the influencing factors. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A flowchart of a method for determining factors affecting battery degradation provided by the present invention;

[0046] Figure 2 A schematic diagram of the discharge capacity decay rate of the experimental group provided by the present invention;

[0047] Figure 3 A schematic diagram of the material polarizability of the experimental group provided by this invention;

[0048] Figure 4 This is a schematic diagram of the discharge capacity decay rate of the comparative group provided by the present invention.

[0049] Figure 5 A schematic diagram of the material polarizability of the comparative group provided by the present invention;

[0050] Figure 6 A schematic diagram of the structure of a system for determining the factors affecting battery degradation provided by the present invention;

[0051] Figure 7 This is a schematic diagram of a device for determining the factors affecting battery degradation provided by the present invention. Detailed Implementation

[0052] The core of this invention is to provide a method, system, and apparatus for determining the factors affecting battery degradation, thereby determining the impact values ​​of internal resistance changes and active lithium loss, and further determining the impact value of material damage, thus locating the influencing factors.

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Figure 1 A flowchart of a method for determining factors affecting battery degradation provided by the present invention includes:

[0055] S11: Charge the battery with a constant current using a first preset current;

[0056] S12: When the battery voltage reaches the first preset voltage, the battery is charged at a constant voltage of the first preset voltage until the charging current of the battery reaches the second preset current, and the first preset current is greater than the second preset current.

[0057] The battery is charged using a constant first preset current. Due to internal polarization, material damage to the positive electrode, increased internal resistance, and loss of active lithium, the battery voltage rises. Therefore, while constant current charging will bring the battery to the first preset voltage, the actual battery capacity may not reach that voltage. Thus, constant voltage charging is used. The first preset voltage for constant voltage charging is the desired charging voltage. For example, if the battery's charging cutoff voltage is 4.25V, then the first preset voltage is 4.25V. This charging voltage is converted into a charging current to charge the lithium battery. During constant voltage charging, the charging current continuously decreases. The second preset current is the battery's charging cutoff current; once this second preset current is reached, charging stops.

[0058] When charging a battery using current, a 1C current is often chosen. 1C is the charging current that fully charges a lithium battery in one minute, and this is used as the first preset current. The second preset current can be 0.05C. Specifically, if an 800A current can fully charge the battery in one hour, then 1C is 800A, and 0.05C is 40A.

[0059] S13: Discharge the battery with a constant current at a third preset current until the battery voltage reaches a second preset voltage, where the second preset voltage is less than the first preset voltage.

[0060] The battery is discharged at a constant current until the discharge cutoff voltage is reached. The constant current discharge current is generally set to 1C. The specific value can be set according to actual needs, and this application does not impose any restrictions here.

[0061] The battery operation consists of constant current charging, constant voltage charging, and constant current discharging as one test cycle, and the above actions are repeated repeatedly.

[0062] S14: Determine the impact values ​​of internal resistance change, active lithium loss, and total impact value based on the battery's total charging capacity, constant voltage charging capacity, discharge capacity, total charging energy, and discharge energy. The total charging capacity is the sum of the constant voltage charging capacity and the constant current charging capacity.

[0063] During cycling, ternary lithium batteries inevitably experience capacity loss or even more severe failure, meaning the capacity retention rate drops below 80%. Many factors contribute to cell failure, including material structural damage leading to cell failure, numerous side reactions hindering electrochemical reactions, and increased impedance. The most significant cause is irreversible material structural damage, with the cathode material undergoing extensive structural collapse, preventing lithium-ion insertion and extraction. This prevents the cell from continuing its complete charge and discharge cycle. Therefore, identifying the patterns of material structural changes during cycling is crucial.

[0064] During charging and discharging, the battery cell employs a constant current and constant voltage charging mode. When the battery is charged to a constant voltage using a constant current method, this voltage is not the battery's true voltage. If voltage limiting is not applied, the battery voltage will continue to rise, leading to internal polarization and eventually damaging the battery structure, resulting in battery failure. The constant voltage charging capacity increases with each cycle, indicating a gradual increase in the degree of material polarization. This polarization is also due to the increased material structure, internal resistance, and loss of active lithium. Therefore, the constant voltage charging capacity represents the change in polarization capacity caused by the increased material structure, internal resistance, and loss of active lithium.

[0065] S15: Determine the material polarization of the battery based on the influence value of internal resistance change, the influence value of active lithium loss, and the total influence value. The material polarization characterizes the influence value of material damage.

[0066] It should be noted that the cycle is generally 300-1500 times.

[0067] This application provides a method for determining the factors affecting battery degradation, applied in the field of battery testing. The method includes performing constant current charging, constant voltage charging, and constant current discharging on the battery. Based on the battery's total charging capacity, constant voltage charging capacity, discharge capacity, total charging energy, and discharge energy, the method determines the influence values ​​of internal resistance change, active lithium loss, and the total influence value. Based on the influence values ​​of internal resistance change, active lithium loss, and the total influence value, the method determines the battery's material polarization, which characterizes the influence value of material damage. Due to the presence of these three influences, a voltage increase occurs. The total influence value of the three influencing factors is determined through the constant voltage charging process. Since both internal resistance change and active lithium loss affect the voltage during the charging process, and voltage is related to energy and capacity, the influence values ​​of internal resistance change and active lithium loss are determined, thereby determining the influence value of material damage and pinpointing the influencing factors.

[0068] Based on the above embodiments:

[0069] In some embodiments, the battery is charged with a constant current at a first preset current, including:

[0070] After the battery has been left to rest for a preset time, it is charged with a constant current using a first preset current.

[0071] The positive electrode material of a lithium-ion battery is usually composed of an active lithium compound, while the negative electrode is carbon with a special molecular structure. During charging, the potential applied to the two electrodes forces the compound in the positive electrode to release lithium ions, which are then embedded in the carbon in the negative electrode, which has a layered molecular structure. During discharging, lithium ions are released from the layered carbon structure and recombine with the compound in the positive electrode. The movement of lithium ions generates current. The positive electrode material needs additives to maintain its activity after multiple charge-discharge cycles, while the negative electrode material needs to be designed at the molecular structure level to accommodate more lithium ions. The electrolyte between the positive and negative electrodes needs to be filled to reduce the internal resistance of the battery, and it needs to have stability and good conductivity.

[0072] Considering the presence of electrolyte in lithium batteries, shaking or other actions can cause them to become unstable. Therefore, a preset resting time is required before charging can begin. Similarly, after constant voltage charging, a preset resting time is also required before constant current discharging.

[0073] Specifically, the preset time can generally be set to 5 minutes.

[0074] In some embodiments, before determining the impact values ​​of internal resistance change and active lithium loss based on the battery's total charging capacity, discharging capacity, total charging energy, and discharging energy, the process includes:

[0075] Based on the total charging capacity C1, the total charging energy W1, and the first relationship... Determine the average charging voltage V av.c ;

[0076] Based on the discharge capacity C2, discharge energy W2, and the second relationship... Determine the average discharge voltage V av.d ;

[0077] The impact values ​​of internal resistance change and active lithium loss are determined based on the battery's total charging capacity, discharging capacity, total charging energy, and discharging energy, including:

[0078] The influence values ​​of internal resistance change and active lithium loss are determined based on the average charging voltage and average discharging voltage.

[0079] Battery capacity refers to the amount of electrical charge a battery can store, usually measured in ampere-hours (Ah). For example, a 1Ah battery means it can provide 1 ampere of current for 1 hour. Battery energy refers to the chemical energy within the battery, that is, the energy the battery can release. It is usually measured in watt-hours (Wh) or joules (J). For example, a 1Wh battery with a voltage of 1 volt can provide 1 ampere of current for 1 hour. The relationship between the two can be expressed by the following formula: Energy (Wh) = Voltage (V) x Capacity (Ah). In other words, a battery's energy is related to its capacity and voltage. At the same voltage, a battery with a larger capacity can store more charge, thus releasing more energy.

[0080] The average charging voltage and average discharging voltage can be determined based on the battery's total charging capacity, discharging capacity, total charging energy, and discharging energy.

[0081] In some embodiments, determining the impact values ​​of internal resistance change and active lithium loss based on the average charging voltage and average discharging voltage includes:

[0082] According to the third relation V av.c =R V +S V and the fourth relation V av.d =R V -S V Determine the effect of internal resistance changes on voltage The effect of active lithium loss on voltage

[0083] The influence value of the internal resistance change is determined based on the voltage affected by the internal resistance change and the average charging voltage.

[0084] The impact value of active lithium loss was determined based on the voltage at which active lithium loss was affected and the average discharge voltage.

[0085] During charging, both internal resistance and active lithium loss lead to an increase in the battery's average voltage, so they are additive. However, during discharging, active lithium loss causes an increase in the average voltage, while internal resistance causes a decrease, so they are subtractive, resulting in the third and fourth relationships. Based on these relationships, we can simultaneously determine the voltage affected by changes in internal resistance and the voltage affected by active lithium loss. The affected voltage refers to the average voltage, thus determining the impact values ​​of internal resistance change and active lithium loss. These two impact values ​​can be understood as the percentage of influence of each factor.

[0086] In some embodiments, determining the total impact value based on the battery's total charging capacity and constant voltage charging capacity includes:

[0087] The total impact value is determined based on the total charging capacity and the constant voltage charging capacity. Where Q represents the constant voltage charging capacity.

[0088] In some embodiments, the material polarization of the battery is determined based on the influence of internal resistance change, the influence of active lithium loss, and the total influence, including:

[0089] Based on the influence values ​​of internal resistance change, active lithium loss, total influence value, and the fifth relational formula Determine the material polarizability Z of the battery.

[0090] By analyzing the causes of cyclic decay using the average voltage method, the voltage change R caused by internal resistance can be determined. V By comparing with the average voltage, the main proportion of internal resistance in the entire polarization process can be determined during charging and discharging. Voltage change S caused by internal resistance V By comparing with the average voltage, the main proportion of internal resistance in the entire polarization process can be determined during charging and discharging. By combining this with the constant voltage charging capacity, we can obtain the capacity contribution of internal resistance throughout the entire polarization capacity. Therefore, after removing the capacity changes caused by internal resistance and active lithium loss from the constant voltage charging capacity, the remaining capacity change is due to material structure variations. Thus, the initial value of the cell's material polarizability before cycling is determined to be... By comparing the polarizability Z of the cell material after cycling, the relative difference between the two can be obtained, which can accurately and effectively express the irreversible changes in the material structure during cycling.

[0091] In some embodiments, before the battery is charged with a constant current at a first preset current, the method further includes:

[0092] Clear the counter;

[0093] After the battery is discharged at a constant current with a third preset current until the battery voltage reaches a second preset voltage, the process also includes:

[0094] Increment the counter by one and check if the preset number of times N has been reached;

[0095] If the target is not met, the process will return to the step of charging the battery with a constant current at the first preset current after a preset time.

[0096] If the target is reached, then calculate the material polarization of the battery for the Nth time.

[0097] In some embodiments, after determining the material polarization of the battery based on the influence value of internal resistance change, the influence value of active lithium loss, and the total influence value, the method further includes:

[0098] Determine the material polarizability of the battery after the first constant current discharge and the material polarizability of the battery after the Nth constant current discharge;

[0099] The difference between the material polarizability of the battery after the Nth constant current discharge and the material polarizability of the battery after the first constant current discharge is determined, and the difference is negatively correlated with the structural stability of the battery material.

[0100] Specifically, in the range of several to a dozen cyclic tests, the material polarizability will not change significantly, so multiple tests are required, and N is generally taken as a value of 300 or more.

[0101] The test procedure consists of constant current charging, constant voltage charging, and constant current discharging, repeated N times. The material polarization rate of the first test and the material polarization rate of the Nth test are calculated. If the deviation is large, it indicates that the positive electrode material of the battery has a high degree of polarization, and the structural stability of the battery is poor.

[0102] Specifically, this application provides an actual implementation method for testing.

[0103] Figure 2 A schematic diagram of the discharge capacity decay rate of the experimental group provided by the present invention;

[0104] Figure 3 A schematic diagram of the material polarizability of the experimental group provided by this invention;

[0105] Experimental group: 0.8AH ternary soft-pack lithium-ion battery to be tested, subjected to room temperature cycle test;

[0106] The loop test steps are as follows:

[0107] 1. Let stand for 5 minutes;

[0108] 2. Constant current and constant voltage charging. The constant current charging current is 1C, and the charging cutoff voltage is set to 4.25V. The constant voltage charging voltage is 4.25V, and the charging cutoff current is set to 0.05C.

[0109] 3. Let stand for 5 minutes;

[0110] 4. Constant current discharge, with the discharge cutoff voltage set to 2.8V;

[0111] 5. Repeat the testing steps 1-4, the number of repetitions depending on the requirements, to complete the loop;

[0112] Obtain the charging capacity, constant voltage capacity, charging energy, and discharging energy of the battery under test during cycling. Its capacity retention during cycling is as follows: Figure 2As shown.

[0113] Calculate R during the cycle of the battery under test. v And average voltage. Average charging voltage V av.c The average discharge voltage V is derived from the charging energy divided by the charging capacity. av.d This is derived from the discharge energy divided by the discharge capacity. Based on the pre-defined calculation formula, the material polarizability before and after cycling is 0.09 and 0.13, respectively. Figure 3 As shown. Combined with Figure 2 It can be seen that after cycling at room temperature, the material structure undergoes very few irreversible structural changes. This method can effectively assess the degree of structural damage to ternary cathode materials during cycling.

[0114] Figure 4 This is a schematic diagram of the discharge capacity decay rate of the comparative group provided by the present invention.

[0115] Figure 5 A schematic diagram of the material polarizability of the comparative group provided by the present invention;

[0116] Comparison group: The 0.8AH ternary soft-pack lithium-ion battery to be tested was subjected to room temperature cycle testing;

[0117] The loop test steps are as follows:

[0118] 1. Let stand for 5 minutes;

[0119] 2. Constant current and constant voltage charging. The constant current charging current is 1C, and the charging cutoff voltage is set to 4.35V. The constant voltage charging voltage is 4.35V, and the charging cutoff current is set to 0.05C.

[0120] 3.5 min;

[0121] 4. Discharge, set the discharge cutoff voltage to 2.8V;

[0122] 5. Repeat the testing steps 1-4, the number of repetitions depending on the requirements, to complete the loop;

[0123] Obtain the charging capacity, constant voltage capacity, charging energy, and discharging energy of the battery under test during cycling, and its capacity decay rate during cycling is as follows: Figure 4 As shown.

[0124] According to the preset calculation formula, the material polarizability before and after the cycle is 0.26 and 0.79, respectively. Figure 5 As shown. Combined with capacity decay Figure 4It can be seen that the ternary material undergoes significant and irreversible structural changes after room temperature cycling. After 300 cycles, the material exhibits obvious structural collapse. Compared with Example 1, the structural deterioration of this batch of ternary materials is more severe, as evidenced by the comparison of material polarizability before and after cycling. This further demonstrates that this method can effectively assess the degree of structural damage to ternary cathode materials during cycling.

[0125] Figure 6 A schematic diagram of a system for determining factors affecting battery degradation provided by the present invention includes:

[0126] The constant current charging unit 61 is used to charge the battery with a first preset current.

[0127] The constant voltage charging unit 62 is used to charge the battery at a constant voltage of the first preset voltage when the battery voltage reaches the first preset voltage, until the charging current of the battery reaches the second preset current, and the first preset current is greater than the second preset current.

[0128] The constant current discharge unit 63 is used to discharge the battery with a third preset current until the battery voltage reaches a second preset voltage, the second preset voltage being less than the first preset voltage.

[0129] The influence value determination unit 64 is used to determine the influence value of internal resistance change, the influence value of active lithium loss and the total influence value based on the battery's total charging capacity, constant voltage charging capacity, discharge capacity, total charging energy and discharge energy. The total charging energy is the sum of constant voltage charging capacity and constant current charging capacity.

[0130] The polarizability determination unit 65 is used to determine the material polarizability of the battery based on the influence value of internal resistance change, the influence value of active lithium loss and the total influence value. The material polarizability characterizes the influence value of material damage.

[0131] Based on the above embodiments,

[0132] The constant current charging unit 61 is specifically used to charge the battery with a first preset current after the battery has been left to rest for a preset time.

[0133] The average charging voltage determination unit is used to determine the average charging voltage based on the total charging capacity C1, the total charging energy W1, and the first relationship. Determine the average charging voltage V av.c ;

[0134] The average discharge voltage determination unit is used to determine the average discharge voltage based on the discharge capacity C2, discharge energy W2, and the second relationship. Determine the average discharge voltage V av.d ;

[0135] The influence value determination unit 64 is specifically used to determine the influence value of internal resistance change and the influence value of active lithium loss based on the average charging voltage and the average discharging voltage.

[0136] The voltage determination unit is used to determine the voltage based on the third relation V. av.c =R V +S V and the fourth relation V av.d =R V -S V Determine the effect of internal resistance changes on voltage The effect of active lithium loss on voltage

[0137] The first influence value determination sub-unit is used to determine the influence value of the internal resistance change based on the influence voltage of the internal resistance change and the average charging voltage.

[0138] The second influence value determination subunit is used to determine the influence value of active lithium loss based on the influence voltage of active lithium loss and the average discharge voltage.

[0139] The third influence value determination subunit is used to determine the total influence value based on the total charging capacity and the constant voltage charging capacity. Where Q represents the constant voltage charging capacity.

[0140] The polarizability determination unit 65 is specifically used to determine the polarizability based on the influence value of internal resistance change, the influence value of active lithium loss, the total influence value, and the fifth relational expression. Determine the material polarizability Z of the battery.

[0141] The clear unit is used to clear the counter;

[0142] The judgment unit is used to increment the counter by one and determine whether the preset number N has been reached; if so, the constant current charging unit 61 is triggered; if so, the calculation unit is triggered.

[0143] The calculation unit is used to calculate the material polarization of the battery in the Nth iteration.

[0144] The polarizability determination unit 65 is specifically used to determine the material polarizability of the battery after the first constant current discharge and the material polarizability of the battery after the Nth constant current discharge.

[0145] The difference determination unit is used to determine the difference between the material polarizability of the battery after the Nth constant current discharge and the material polarizability of the battery after the first constant current discharge. The difference is negatively correlated with the structural stability of the battery material.

[0146] Figure 7 The present invention provides a schematic diagram of a device for determining factors affecting battery degradation, the device comprising:

[0147] Memory 71 is used to store computer programs;

[0148] The processor 72 is used to implement the steps of the method for determining the factors affecting battery degradation when executing a computer program.

[0149] The description of the device for determining the factors affecting battery degradation provided in this application is the same as described in the above embodiments, and will not be repeated here.

[0150] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0151] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining a battery degradation influencing factor, characterized in that, include: The battery is charged with a constant current using a first preset current; When the voltage of the battery reaches a first preset voltage, the battery is charged at a constant voltage of the first preset voltage until the charging current of the battery reaches a second preset current, wherein the first preset current is greater than the second preset current. The battery is discharged at a constant current with a third preset current until the voltage of the battery reaches a second preset voltage, where the second preset voltage is less than the first preset voltage. The influence values ​​of internal resistance change, active lithium loss, and total influence value are determined based on the total charging capacity, constant voltage charging capacity, discharge capacity, total charging energy, and discharge energy of the battery. The total charging capacity is the sum of the constant voltage charging capacity and the constant current charging capacity. The material polarization of the battery is determined based on the influence value of the internal resistance change, the influence value of the active lithium loss, and the total influence value. The material polarization characterizes the influence value of material damage. Before determining the impact values ​​of internal resistance change and active lithium loss based on the battery's total charging capacity, discharging capacity, total charging energy, and discharging energy, the following steps are included: Based on the total charging capacity The total charging energy and the first relation Determine the average charging voltage ; According to the discharge capacity The discharge energy and the second relation Determine the average discharge voltage ; The impact values ​​of internal resistance change and active lithium loss are determined based on the battery's total charging capacity, discharging capacity, total charging energy, and discharging energy, including: The influence values ​​of internal resistance change and active lithium loss are determined based on the average charging voltage and the average discharging voltage. The influence values ​​of internal resistance change and active lithium loss are determined based on the average charging voltage and the average discharging voltage, including: According to the third relation and the fourth relation Determine the effect voltage of the internal resistance change. and the effect voltage of the loss of active lithium. ; The influence value of the internal resistance change is determined based on the voltage affected by the internal resistance change and the average charging voltage. ; The impact value of active lithium loss is determined based on the voltage at which the active lithium loss occurs and the average discharge voltage. ; The total impact value is determined based on the battery's total charging capacity and constant voltage charging capacity, including: The total influence value is determined based on the total charging capacity and the constant voltage charging capacity. ,in The constant voltage charging capacity; The material polarizability of the battery is determined based on the influence value of the internal resistance change, the influence value of the active lithium loss, and the total influence value, including: Based on the influence value of the internal resistance change, the influence value of the active lithium loss, the total influence value, and the fifth relationship... Determine the material polarizability of the battery .

2. The method for determining the factors affecting battery degradation as described in claim 1, characterized in that, The battery is charged at a constant current with a first preset current, including: After the battery has been left to rest for a preset time, the battery is charged with a constant current using a first preset current.

3. The method for determining the factors affecting battery degradation as described in any one of claims 1 to 2, characterized in that, Before charging the battery with a first preset current, the method further includes: Clear the counter; After the battery is subjected to constant current discharge at a third preset current until the battery voltage reaches a second preset voltage, the process further includes: Increment the counter by one and determine whether the preset number N has been reached, where N is a positive integer; If the target is not met, the process returns to the step of charging the battery with a first preset current after a preset time. If the target is reached, then the material polarization of the battery for the Nth time is calculated.

4. The method for determining the factors affecting battery degradation as described in claim 3, characterized in that, After determining the material polarizability of the battery based on the influence value of the internal resistance change, the influence value of the active lithium loss, and the total influence value, the method further includes: Determine the material polarization of the battery after the first constant current discharge and the material polarization of the battery after the Nth constant current discharge; The difference between the material polarizability of the battery after the Nth constant current discharge and the material polarizability of the battery after the first constant current discharge is determined, and the difference is negatively correlated with the structural stability of the battery material.

5. A system for determining factors affecting battery degradation, characterized in that, include: A constant current charging unit is used to charge the battery with a first preset current at a constant current. A constant voltage charging unit is used to charge the battery at a constant voltage of the first preset voltage when the voltage of the battery reaches the first preset voltage, until the charging current of the battery reaches the second preset current, wherein the first preset current is greater than the second preset current. A constant current discharge unit is used to discharge the battery with a third preset current until the voltage of the battery reaches a second preset voltage, wherein the second preset voltage is less than the first preset voltage. The influence value determination unit is used to determine the influence value of internal resistance change, the influence value of active lithium loss, and the total influence value based on the total charging capacity, constant voltage charging capacity, discharge capacity, total charging energy, and discharge energy of the battery. The total charging capacity is the sum of constant voltage charging capacity and constant current charging capacity. A polarizability determination unit is used to determine the material polarizability of the battery based on the influence value of the internal resistance change, the influence value of the active lithium loss, and the total influence value, wherein the material polarizability characterizes the influence value of material damage. The average charging voltage determination unit is used to determine the average charging voltage based on the total charging capacity. The total charging energy and the first relation Determine the average charging voltage ; The average discharge voltage determination unit is used to determine the average discharge voltage based on the discharge capacity. The discharge energy and the second relation Determine the average discharge voltage ; The influence value determination unit is specifically used to determine the influence value of internal resistance change and the influence value of active lithium loss based on the average charging voltage and the average discharging voltage. The voltage determination unit is used to determine the voltage based on the third relation. and the fourth relation Determine the effect voltage of the internal resistance change. and the effect voltage of the loss of active lithium. ; The first influence value determination subunit is used to determine the influence value of the internal resistance change based on the influence voltage of the internal resistance change and the average charging voltage. ; The second influence value determination subunit is used to determine the influence value of active lithium loss based on the influence voltage of active lithium loss and the average discharge voltage. ; The third influence value determination subunit is used to determine the total influence value based on the total charging capacity and the constant voltage charging capacity. ,in The constant voltage charging capacity; The polarizability determination unit is specifically used to determine the polarizability based on the influence value of the internal resistance change, the influence value of the active lithium loss, the total influence value, and the fifth relational expression. Determine the material polarizability of the battery .

6. A device for determining factors affecting battery degradation, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the method for determining the factors affecting battery degradation as described in any one of claims 1 to 4.

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