Method for predicting electrolyte consumption, method and device for predicting cycle life

Abstract

The application discloses a kind of electrolyte consumption prediction method, cycle life prediction method and device, the first consumption of the constant-volume process of formation is determined, the second consumption of aging process is determined, the capacity loss of any SOH in aging process is determined, and the total consumption of electrolyte at any SOH is predicted according to the second consumption and capacity loss, to realize the prediction of electrolyte consumption.It can also be according to the ratio of the total consumption of the target SOH predicted and the third consumption of electrolyte in a cycle in the aging process, to predict the cycle life of lithium iron phosphate battery when attenuated to target SOH, to realize the prediction of cycle life.As a small amount of data and limited cycle test, cycle life can be predicted, so that the test time of cycle life prediction can be reduced, test resources can be saved, prediction efficiency can be improved, and the development cycle of lithium iron phosphate battery product can be shortened.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a method and apparatus for predicting electrolyte consumption and cycle life. Background Technology

[0002] Lithium iron phosphate (LFP) batteries possess advantages such as high operating voltage, high energy density, long cycle life, good safety performance, low self-discharge rate, and no memory effect. Before being put into use, LFP batteries must undergo numerous performance tests, including high and low temperature performance testing, rate performance testing, long-term cycle performance testing, and safety performance testing. Among these, long-term cycle performance testing is a crucial indicator for measuring the lifespan of LFP batteries. However, due to the very long cycle life of LFP batteries, reaching 6000-15000 cycles, predicting cycle life using long-term cycle performance testing requires a lengthy testing time, severely impacting the product development cycle of LFP batteries. Therefore, how to shorten the testing time to predict the cycle life of LFP batteries is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0003] This invention provides a method and apparatus for predicting electrolyte consumption, cycle life, and other related parameters, in order to solve the problem of how to predict the cycle life of lithium iron phosphate batteries with a relatively short testing time.

[0004] In a first aspect, embodiments of the present invention provide a method for predicting electrolyte consumption in lithium iron phosphate batteries, including:

[0005] The first consumption of electrolyte is determined based on the first charge capacity of the lithium iron phosphate battery during the first charge, the first discharge capacity during the first discharge, the total amount of electrolyte in the lithium iron phosphate battery before formation and capacitance, and the first remaining amount of electrolyte after formation and capacitance. The first consumption is: the amount of electrolyte consumed when the lithium iron phosphate battery loses 1Ah of capacity during formation and capacitance.

[0006] Based on the first consumption, a second consumption of the lithium iron phosphate battery is determined, wherein the second consumption is the amount of electrolyte consumed when the lithium iron phosphate battery loses 1Ah of capacity during the aging process.

[0007] Based on the initial discharge capacity, determine the capacity loss of the lithium iron phosphate battery at any state of zero (SOH) during the aging process.

[0008] The total electrolyte consumption of the lithium iron phosphate battery at the SOH is determined by multiplying the second consumption amount by the capacity loss amount corresponding to the SOH.

[0009] Secondly, embodiments of the present invention provide a method for predicting the cycle life of a lithium iron phosphate battery, comprising:

[0010] Using the prediction method described in the first aspect, the total electrolyte consumption of the lithium iron phosphate battery at the target SOH is predicted;

[0011] The third consumption of electrolyte in the lithium iron phosphate battery during one cycle of aging is determined; one cycle is defined as the lithium iron phosphate battery completing one charge and one discharge cycle.

[0012] Based on the predicted ratio of the total consumption to the third consumption, the cycle life of the lithium iron phosphate battery when it degrades to the target SOH is predicted.

[0013] Thirdly, embodiments of the present invention provide a device for predicting electrolyte consumption in a lithium iron phosphate battery, comprising:

[0014] Memory, used to store program instructions;

[0015] A processor is configured to invoke the program instructions stored in the memory and execute the prediction method as described in the first aspect according to the obtained program.

[0016] Fourthly, embodiments of the present invention provide a cycle life prediction device for lithium iron phosphate batteries, comprising:

[0017] Memory, used to store program instructions;

[0018] A processor is configured to invoke the program instructions stored in the memory and execute the cycle lifetime prediction method as described in the second aspect according to the obtained program.

[0019] The beneficial effects of this invention are as follows:

[0020] This invention provides a method and apparatus for predicting electrolyte consumption, cycle life, and overall electrolyte life. By determining the first electrolyte consumption per 1Ah capacity loss during the formation and capacitance process, and the second electrolyte consumption per 1Ah capacity loss during the aging process, and based on the initial discharge capacity, the capacity loss at any state of equilibrium (SOH) during the aging process is determined. Then, by multiplying the second consumption and the capacity loss, the total electrolyte consumption at any SOH of the lithium iron phosphate battery can be predicted, thus achieving electrolyte consumption prediction. Furthermore, by using the ratio of the predicted total electrolyte consumption at the target SOH to the third electrolyte consumption after one cycle during the aging process, the cycle life of the lithium iron phosphate battery at the target SOH can be predicted, thereby achieving cycle life prediction. Since the cycle life of the lithium iron phosphate battery can be predicted with only a small amount of data and limited cycle testing, the testing time required for cycle life prediction can be reduced, testing resources can be saved, prediction efficiency can be improved, and the development cycle of lithium iron phosphate battery products can be shortened. Attached Figure Description

[0021] Figure 1 This is a flowchart of an electrolyte consumption prediction method provided in an embodiment of the present invention;

[0022] Figure 2 This is a flowchart of a cycle lifetime prediction method provided in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of a measured cycle life provided in an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the structure of a consumption prediction device provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of a cycle life prediction device provided in an embodiment of the present invention. Detailed Implementation

[0026] The specific embodiments of the electrolyte consumption prediction method, cycle life prediction method, and apparatus provided by the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a method for predicting electrolyte consumption in lithium iron phosphate batteries, such as... Figure 1 As shown, the prediction method includes the following steps:

[0028] S101. Based on the initial charge capacity of the lithium iron phosphate battery during the first charge, the initial discharge capacity during the first discharge, the total amount of electrolyte in the lithium iron phosphate battery before formation and capacitance, and the first remaining amount of electrolyte after formation and capacitance, determine the first consumption of electrolyte. The first consumption is: the amount of electrolyte consumed when the lithium iron phosphate battery loses 1Ah of capacity during formation and capacitance.

[0029] S102. Based on the first consumption, determine the second consumption of the lithium iron phosphate battery. The second consumption is the amount of electrolyte consumed when the lithium iron phosphate battery loses 1Ah of capacity during the aging process.

[0030] S103. Based on the initial discharge capacity, determine the capacity loss of the lithium iron phosphate battery at any state of zero (SOH) during the aging process.

[0031] S104. Determine the total electrolyte consumption of the lithium iron phosphate battery at the SOH state based on the product of the second consumption amount and the capacity loss amount corresponding to the SOH state.

[0032] It should be understood that step S103 can also be executed between S101 and S102 or before S101. The execution order of S101 and S103 can be arbitrarily interchanged and is not limited here.

[0033] Thus, when predicting the total electrolyte consumption during the aging process through the above steps, it is only necessary to base it on the electrolyte consumption per 1Ah capacity loss during the formation and volume-keeping process, without considering the actual operating conditions of the aging process. Therefore, this prediction method requires less data, which can reduce the test time required for total consumption prediction, save test resources, improve prediction efficiency, and provide data support for subsequent cycle life prediction.

[0034] It should be understood that the main causes of failure in lithium iron phosphate batteries include: loss of active lithium, loss of positive electrode material, and loss of negative electrode material. Among these, battery failure caused by loss of active lithium is dominant, while the losses of positive and negative electrode materials are almost negligible. Therefore, the above prediction method is based on the loss of active lithium to predict the total consumption of electrolyte.

[0035] In step S102, when determining the second consumption amount of the lithium iron phosphate battery based on the first consumption amount, it can be assumed that: for lithium iron phosphate batteries, the electrolyte consumption amount corresponding to 1Ah capacity loss during the formation and capacitance process is approximately the same as the electrolyte consumption amount corresponding to 1Ah capacity loss during the aging process. This is because: electrolyte consumption mainly occurs through two pathways, namely, consumption caused by the growth and repair of the solid electrolyte interphase (SEI) membrane, and consumption caused by side reactions of the electrolyte itself (such as thermal decomposition). For the growth and repair of the SEI, the reaction involved is: solvent molecules (such as DMC, i.e., dimethyl carbonate) + Li+ +e - →SEI, solvent molecules and active lithium (i.e., Li) + The consumption ratio is 1:1. Regarding the side reactions of the electrolyte itself: although the proportion of side reactions in the total loss of active lithium is small, side reactions are still a significant part of Li... + This is caused by the combined action of the solvent and Li. + The ratio of solvent consumption is approximately 1:1.

[0036] Both the formation and aging processes involve the loss of active lithium, and the loss mechanisms are the same. Since capacity loss in lithium iron phosphate batteries corresponds to active lithium loss, it can be assumed that the electrolyte consumption per unit of active lithium loss (i.e., 1 Ah capacity loss) during the formation and aging process is approximately the same as the electrolyte consumption per unit of active lithium loss (i.e., 1 Ah capacity loss) during the aging process. Therefore, based on the first electrolyte consumption during the formation and aging process, the second electrolyte consumption during the aging process can be determined. Furthermore, the conditions of the aging process are irrelevant, as active lithium loss will occur regardless of the conditions. Therefore, the electrolyte consumption can be calculated solely based on the active lithium loss, which also improves the accuracy of the prediction results.

[0037] Furthermore, based on the first consumption, the second consumption of the lithium iron phosphate battery is determined. The determined first consumption can be used as the second consumption, meaning the first consumption equals the second consumption. Thus, through a simple process, the second consumption of the lithium iron phosphate battery can be determined in a short time, improving the prediction efficiency of the total electrolyte consumption.

[0038] Of course, other methods can be used to determine the second consumption of lithium iron phosphate batteries based on the first consumption, and these methods are not limited here. For example, the product of the first consumption and a preset coefficient can be used as the second consumption, and the preset coefficient can be obtained based on actual experience.

[0039] Furthermore, when the electrolyte of a lithium iron phosphate battery contains additives, the presence of these additives hinders the reaction between the solvent and active lithium, resulting in a non-1:1 ratio between solvent loss and active lithium loss, typically less than 1:1. When solvent loss is considered as electrolyte consumption, the actual electrolyte consumption decreases due to the reduced solvent loss. However, if the prediction method described above is still applied, the predicted electrolyte consumption will be higher than the actual consumption because the method is based on a 1:1 ratio of solvent loss to active lithium loss. Therefore, this prediction method is suitable for lithium iron phosphate batteries with no additives or very low additive content in the electrolyte.

[0040] Thus, the total electrolyte consumption at any state of oxygen (SOH) can be determined through the above steps, providing data for subsequent prediction of the cycle life of lithium iron phosphate batteries.

[0041] In some embodiments, the capacity loss at any state of oxygen (SOH) during the aging process can be calculated using the following formula:

[0042] L SOH =Q×(1-SOH)

[0043] Among them, L SOH This represents the capacity loss at the state of zero discharge (SOH), and Q represents the initial discharge capacity.

[0044] Thus, Formula 1 can be used to calculate the capacity loss at any SOH level during the aging process relative to the initial discharge capacity, providing a basis for predicting the total electrolyte consumption.

[0045] In some embodiments, determining the first consumption of electrolyte based on the initial charge capacity of the lithium iron phosphate battery during its first charge, the initial discharge capacity during its first discharge, the total amount of electrolyte in the lithium iron phosphate battery before formation and capacitation, and the first remaining amount of electrolyte after formation and capacitation, includes the following process:

[0046] Process 1: Determine the amount of electrolyte consumed during the constant volume formation based on the total amount of electrolyte and the first remaining amount;

[0047] Specifically, the amount of electrolyte consumed during constant volume formation can be determined using the following formula:

[0048] △w=W0-W

[0049] Where Δw represents the amount of electrolyte consumed when the electrolyte is converted to constant volume, w0 represents the total amount of electrolyte before conversion to constant volume, and w represents the first remaining amount of electrolyte after conversion to constant volume.

[0050] Furthermore, the total amount of electrolyte before formation and the first remaining amount of electrolyte after formation and volume determination can be obtained by the dichloromethane external standard method. Of course, other testing methods can also be used, and there are no limitations here.

[0051] Process 2: Determine the capacity loss during formation to constant capacity based on the initial charge capacity and initial discharge capacity;

[0052] Specifically, the capacity loss when converting to constant volume can be determined using the following formula:

[0053] AQ = Q0 - Q

[0054] Wherein, ΔQ represents the capacity loss during the formation to a constant capacity, Q0 represents the initial charge capacity, and Q represents the initial discharge capacity. Furthermore, the methods for determining the initial charge capacity and the initial discharge capacity can be implemented in any way known to those skilled in the art that can obtain the initial charge capacity and the initial discharge capacity, and are not limited herein.

[0055] Process 3: Determine the first consumption amount based on the amount of electrolyte consumed during formation and the amount of capacity loss during formation and volume determination.

[0056] Specifically, the first consumption amount can be determined using the following formula four:

[0057]

[0058] Wherein, U1 represents the first consumption amount.

[0059] In this way, the first consumption can be determined based on the initial charge capacity, the initial discharge capacity, the total amount of electrolyte before formation and volume control, and the first remaining amount of electrolyte after formation and volume control, providing data basis for predicting the total consumption of electrolyte.

[0060] In some embodiments, the total electrolyte consumption of the lithium iron phosphate battery at the SOH is determined based on the product of the second consumption and the capacity loss corresponding to the SOH, including:

[0061] The total electrolyte consumption can be predicted using the following formula:

[0062]

[0063] Among them, Y SOH This indicates the total amount of electrolyte consumed when SOH is reached.

[0064] Thus, by using Formula 5, the data obtained when the electrolyte needs to be converted to a constant volume can be used to predict the total electrolyte consumption at any SOH during the aging process. This can reduce the testing time required for predicting electrolyte consumption, save testing resources, improve prediction efficiency, and provide data basis for subsequent cycle life prediction.

[0065] In some embodiments, the method further includes: determining a second remaining amount of electrolyte at the SOH state based on the total amount of electrolyte consumed at the SOH state; and performing a second electrolyte injection on the lithium iron phosphate battery when the determined second remaining amount is less than a threshold.

[0066] Specifically, the second remaining amount of electrolyte can be determined using the following formula six:

[0067] W sOH =W0-Y SOH

[0068] Among them, w SOHThis indicates the second remaining amount of electrolyte when the SOH is present.

[0069] Therefore, for long-cycle lithium iron phosphate batteries requiring multiple electrolyte injections, electrolyte needs to be injected into the battery when the remaining electrolyte level is below a certain threshold to ensure normal battery operation. The threshold value can be set based on the actual application scenario and battery usage requirements, and is not limited here.

[0070] Furthermore, during the secondary electrolyte injection, the injected electrolyte volume is greater than or equal to the total electrolyte consumption at that SOH level. That is, the injected volume ≥ Y. SOH This provides a range for the amount of electrolyte injected during secondary electrolyte filling, which helps to keep the amount of electrolyte in the battery at a reasonable value after filling, ensuring the normal operation of the long-cycle energy storage lithium iron phosphate battery.

[0071] The method for predicting electrolyte consumption provided in this invention will be explained below with reference to specific embodiments.

[0072] The following is an example of measuring the electrolyte content using the dichloromethane external standard method.

[0073] S11. After filling several lithium iron phosphate batteries with electrolyte, let them stand at room temperature for a certain period of time to allow the electrolyte to fully soak in.

[0074] S12. Divide all batteries into three groups, labeled A, B, and C. Inject a certain amount of dichloromethane into the batteries of group A through the injection port. Use an ultrasonic machine to accelerate the mixing of dichloromethane and electrolyte for a certain period of time. After standing at room temperature for a certain period of time, disassemble the batteries in a glove box where H2O < 0.1 ppm and O2 < 0.1 ppm. Measure a certain amount of the mixture of electrolyte and dichloromethane. Use a gas chromatography-mass spectrometry (GC-MS) instrument to test the concentration of each component in the mixture. Calculate the absolute content of each component in the electrolyte at this time using the concentration of dichloromethane and the amount added, and obtain the total amount of electrolyte w0g (excluding the mass of dichloromethane).

[0075] It should be understood that when injecting electrolyte into a battery, the amount is usually injected according to the pre-designed amount. However, due to possible losses during the injection process, there may be a difference between the actual amount injected and the designed amount. Therefore, the actual amount injected can be measured in step S12 and used as the calculation benchmark in subsequent calculations.

[0076] S13. Perform formation and capacity-fixing treatment on the batteries of group B and group C to obtain the average first charge capacity of the batteries, denoted as Q0, and the average first discharge capacity, denoted as Q.

[0077] S14. Adjust the SOC of the B group battery to the preset value, inject a certain amount of dichloromethane, sonicate for a certain time using an ultrasonic machine, let it stand at room temperature for a certain time, disassemble the battery in a glove box with H2O < 0.1ppm and O2 < 0.1ppm, measure a certain amount of the electrolyte and dichloromethane mixture, use GC-MS to test the concentration of each component in the mixture, calculate the absolute content of each component in the electrolyte at this time using the concentration of dichloromethane and the amount added, and obtain the first remaining amount of electrolyte wg (excluding the mass of dichloromethane).

[0078] The preset value can be, but is not limited to, 30%. This is because when the SOC of the battery after formation and capacitance is 30%, the physicochemical properties of the battery are relatively stable, which can improve the accuracy of the measurement results. Of course, the preset value can also be other values, and can be set according to actual needs. There are no restrictions here.

[0079] The following example illustrates this.

[0080] Before the formation and volume determination, based on the above step S12, the total amount of electrolyte in the two different lithium iron phosphate batteries is measured. Not only the total amount of electrolyte can be obtained, but also the proportion of each component in the electrolyte. The specific results are shown in Table 1. The designed proportion refers to the proportion of each component preset before battery preparation, and the measured proportion refers to the actual proportion of each component in the electrolyte after battery preparation. EC is ethylene carbonate, EMC is ethyl methyl carbonate, DMC is dimethyl carbonate, and LiPF6 is lithium hexafluorophosphate.

[0081] Table 1

[0082]

[0083] As shown in Table 1, the designed proportions of each component differ from the measured proportions for the two different lithium iron phosphate batteries, indicating that losses occurred during injection, leading to the discrepancy between the designed and measured proportions. Therefore, to improve the accuracy of the prediction results, measured data are used for prediction.

[0084] After the formation and volume determination, based on the above step S14, the first remaining amount of electrolyte in the two different lithium iron phosphate batteries is measured. Not only can the first remaining amount of electrolyte be obtained, but also the absolute amount of each component in the electrolyte can be obtained. The specific results are shown in Table 2.

[0085] Table 2

[0086]

[0087] After the formation and capacitance are completed, based on the above step S13, the first charge capacity and first discharge capacity of two different lithium iron phosphate batteries can also be obtained, and the specific results are shown in Table 3.

[0088] Table 3

[0089]

[0090] In Table 3, the capacity loss is the difference between the initial charge capacity and the initial discharge capacity. Specifically, for Sample 1, the capacity loss is calculated as: 2.6211Ah - 2.2921Ah = 0.3290Ah; for Sample 2, the capacity loss is calculated as: 2.6158Ah - 2.2924Ah = 0.3234Ah. The electrolyte consumption during formation and capacitance is the difference between the total electrolyte volume w0 before formation and capacitance and the initial remaining volume. Specifically, for Sample 1, the electrolyte consumption during formation and capacitance is calculated as follows: 11g - 10.05g = 0.95g. For Sample 2, the calculation process for the amount of electrolyte consumed during formation and volume control is: 11.02g - 9.83g = 1.19g. The first consumption is the ratio of the amount of electrolyte consumed to the capacity loss during formation and volume control. That is, for Sample 1, the calculation process for the first consumption is: 0.95g / 0.329Ah = 2.88g / Ah, and for Sample 2, the calculation process for the first consumption is: 1.19g / 0.3234Ah = 3.68g / Ah.

[0091] Furthermore, based on the data in Tables 3 and 4, and combined with Formula 5 above, taking an SOH content of 20% as an example, the total electrolyte consumption of Sample 1 can be calculated. The calculation process is as follows:

[0092]

[0093] The total electrolyte consumption for sample two can be calculated as follows:

[0094]

[0095] The above results are the predicted total electrolyte consumption at 20% SOH. For the lithium iron phosphate battery of Sample 1, the total consumption is 5.295g, and for the lithium iron phosphate battery of Sample 2, the total consumption is 6.748g.

[0096] Based on this, through the above steps S1-S4, the initial charge capacity, initial discharge capacity, total electrolyte volume, and initial remaining volume can be determined. Based on these data, the initial consumption can be further calculated, which is beneficial for predicting the total electrolyte consumption.

[0097] Based on the same inventive concept, embodiments of the present invention provide a method for predicting the cycle life of lithium iron phosphate batteries, such as... Figure 2 As shown, it includes the following steps:

[0098] S201. Using the above method for predicting electrolyte consumption, predict the total electrolyte consumption at the target SOH.

[0099] Here, the target SOH can be understood as the SOH level when the battery can no longer meet the usage requirements of the application scenario. For example, assuming that the battery can no longer meet the usage requirements of the application scenario when the SOH is 20%, the total electrolyte consumption when the SOH is 20% can be predicted based on the above method for predicting electrolyte consumption.

[0100] S202. Determine the third electrolyte consumption of a lithium iron phosphate battery during one cycle of aging; wherein, one cycle is: the lithium iron phosphate battery completes one charge and one discharge cycle.

[0101] S203. Based on the ratio of the predicted total consumption to the third consumption, predict the cycle life of the lithium iron phosphate battery when it degrades to the target SOH.

[0102] In other words, the predicted cycle life refers to the number of cycles a lithium iron phosphate battery undergoes from its current state to the target state of zero (SOH).

[0103] It should be understood that since this cycle life prediction method is based on the prediction method of total electrolyte consumption, it also has the same assumption as the prediction method of total electrolyte consumption. The content of this assumption and the reason for proposing this assumption can be found in the embodiments of the aforementioned prediction method. Repeated parts will not be repeated.

[0104] Thus, the cycle life of lithium iron phosphate batteries can be predicted with a small amount of data and limited cycle testing. This reduces the testing time required for cycle life prediction, saves testing resources, improves prediction efficiency, and shortens the development cycle of lithium iron phosphate battery products.

[0105] In addition, determining the third amount of electrolyte consumed by a lithium iron phosphate battery during one cycle of aging can include: determining the fourth amount of electrolyte consumed by a lithium iron phosphate battery during n cycles of aging, where n is a positive integer; and then determining the third amount of electrolyte consumed based on the ratio of the fourth amount of electrolyte consumed to n.

[0106] Specifically, the third consumption amount can be determined using the following formula seven:

[0107]

[0108] Where U3 represents the third consumption amount and b represents the fourth consumption amount.

[0109] One point to note is that the amount of electrolyte consumed per battery cycle may vary. Therefore, when calculating the third electrolyte consumption per cycle, an average value can be calculated based on the ratio of the total electrolyte consumption over n cycles to n. This average value can then be used as the third electrolyte consumption per cycle. The value of n can be further set to 50 ≤ n ≤ 200, but this is not a fixed value. This reduces the calculation error of the third consumption and improves the accuracy of cycle life prediction.

[0110] In some embodiments, step S203 above can be specifically expressed as the following formula (i.e., formula eight):

[0111]

[0112] Among them, Life SOH This indicates the cycle life at which the load decays to the target SOH.

[0113] Thus, Formula 8 requires only a small amount of data and limited cycle testing to accurately predict the cycle life of lithium iron phosphate batteries. This reduces the testing time needed for cycle life prediction, saves testing resources, improves prediction efficiency, and shortens the development cycle of lithium iron phosphate battery products.

[0114] The cycle life prediction method provided by the present invention will be explained below with reference to specific embodiments.

[0115] Cycle tests were performed on the batteries after formation and capacitance to obtain the amount of electrolyte consumed per 200 cycles. The specific results are shown in Table 4, where b n This indicates the amount of electrolyte consumed every 200 weeks.

[0116] Table 4

[0117] <![CDATA[b n / g]]> 0.060 0.057 0.059 0.061 0.061 0.061 0.058 0.057 0.062 0.058

[0118] Based on the data in Table 4, b can be calculated. n The average value is taken as the fourth electrolyte consumption (i.e., b) after 200 cycles; where b n The formula for calculating the average value is as follows:

[0119]

[0120] According to Formula 8, assuming the target SOH is 80%, n is 200, and Q is 2.29, When the value is 3.28, the cycle life can be predicted:

[0121]

[0122] The above results represent the predicted number of cycles required to decay from the current state to 80% SOH, and... Figure 3 Compared with the actual measurement results shown, it can be found that the predicted cycle life of lithium iron phosphate batteries is close to that of the actual test results of 5164, indicating that the prediction method can accurately predict the cycle life of lithium iron phosphate batteries and improve the accuracy of the prediction results.

[0123] Based on the same inventive concept, this invention also provides a device for predicting electrolyte consumption in lithium iron phosphate batteries. The implementation principle of this device is similar to that of the aforementioned method for predicting electrolyte consumption. For details on the specific implementation of this device, please refer to the embodiments of the aforementioned method for predicting electrolyte consumption.

[0124] Specifically, the embodiment of the present invention provides an electrolyte consumption prediction device, such as... Figure 4 As shown, it may include:

[0125] Memory 401 is used to store program instructions;

[0126] The processor 402 is used to call the program instructions stored in the memory 401 and execute the electrolyte consumption prediction method as described above according to the obtained program.

[0127] Based on the same inventive concept, this invention also provides a device for predicting the cycle life of a lithium iron phosphate battery. The implementation principle of this device is similar to that of the aforementioned method for predicting cycle life. For details on the specific implementation of this device, please refer to the embodiments of the aforementioned method for predicting cycle life. Repeated descriptions will not be repeated.

[0128] Specifically, embodiments of the present invention provide a cycle life prediction device, such as... Figure 5 As shown, it may include:

[0129] Memory 501 is used to store program instructions;

[0130] Processor 502 is used to call program instructions stored in memory 501 and execute the cycle lifetime prediction method as described above according to the obtained program.

[0131] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for predicting electrolyte consumption in lithium iron phosphate batteries, characterized in that, include: The first consumption of electrolyte is determined based on the first charge capacity of the lithium iron phosphate battery during the first charge, the first discharge capacity during the first discharge, the total amount of electrolyte in the lithium iron phosphate battery before formation and capacitance, and the first remaining amount of electrolyte after formation and capacitance. The first consumption is: the amount of electrolyte consumed when the lithium iron phosphate battery loses 1Ah of capacity during formation and capacitance. Based on the first consumption, a second consumption of the lithium iron phosphate battery is determined, wherein the second consumption is the amount of electrolyte consumed when the lithium iron phosphate battery loses 1Ah of capacity during the aging process. Based on the initial discharge capacity, determine the capacity loss of the lithium iron phosphate battery at any state of zero oxygen (SOH) during the aging process. The total electrolyte consumption of the lithium iron phosphate battery at the SOH is determined by multiplying the second consumption amount by the capacity loss amount corresponding to the SOH.

2. The prediction method as described in claim 1, characterized in that, Based on the initial discharge capacity, determine the capacity loss of the lithium iron phosphate battery at any state of equilibrium (SOH) during the aging process, including: The capacity loss corresponding to the SOH is calculated using the following formula: L=Q×(1-SOH) Where Q represents the initial discharge capacity, and L represents the capacity loss corresponding to the SOH.

3. The prediction method as described in claim 1, characterized in that, The first consumption of electrolyte is determined based on the initial charge capacity of the lithium iron phosphate battery during its first charge, the initial discharge capacity during its first discharge, the total amount of electrolyte in the lithium iron phosphate battery before formation and volume stabilization, and the first remaining amount of electrolyte after formation and volume stabilization. This includes: The amount of electrolyte consumed during the formation and volume determination is determined based on the total amount of electrolyte and the first remaining amount. The capacity loss during the formation and capacities is determined based on the initial charge capacity and the initial discharge capacity. The first consumption amount is determined based on the ratio of the amount of electrolyte consumed during the formation and volume determination to the amount of capacity loss during the formation and volume determination.

4. The prediction method as described in claim 1, characterized in that, Based on the first consumption amount, determining the second consumption amount of the lithium iron phosphate battery includes: The determined first consumption amount is then designated as the second consumption amount.

5. The prediction method according to any one of claims 1-4, characterized in that, Also includes: Based on the total amount of electrolyte consumed at the SOH state, a second remaining amount of electrolyte at the SOH state is determined. When the determined second remaining amount is less than the threshold, the lithium iron phosphate battery is injected with electrolyte a second time.

6. The prediction method as described in claim 5, characterized in that, During the secondary injection, the amount of electrolyte injected is greater than or equal to the total amount of electrolyte consumed when the SOH is reached.

7. A method for predicting the cycle life of a lithium iron phosphate battery, characterized in that, include: Using the prediction method described in any one of claims 1-6, the total electrolyte consumption of the lithium iron phosphate battery at the target SOH is predicted; The third consumption of electrolyte in the lithium iron phosphate battery during one cycle of aging is determined; one cycle is defined as the lithium iron phosphate battery completing one charge and one discharge cycle. Based on the predicted ratio of the total consumption to the third consumption, the cycle life of the lithium iron phosphate battery when it degrades to the target SOH is predicted.

8. The cycle life prediction method as described in claim 7, characterized in that, Determining the third consumption of the electrolyte after one cycle of the lithium iron phosphate battery during the aging process includes: Determine the fourth amount of electrolyte consumed when the lithium iron phosphate battery is cycled n times during the aging process, where n is a positive integer; The third consumption amount is determined based on the ratio of the fourth consumption amount to n.

9. A device for predicting electrolyte consumption in a lithium iron phosphate battery, characterized in that, include: Memory, used to store program instructions; A processor is configured to invoke the program instructions stored in the memory and execute the prediction method as described in any one of claims 1-6 according to the obtained program.

10. A device for predicting the cycle life of a lithium iron phosphate battery, characterized in that, include: Memory, used to store program instructions; A processor is configured to invoke the program instructions stored in the memory and execute the cycle lifetime prediction method as described in any one of claims 7-8 according to the obtained program.

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