Lithium precipitation inflection point detection method and device, storage medium and computer equipment

Abstract

The invention relates to the technical field of batteries, and particularly provides a lithium precipitation inflection point detection method and device, a storage medium and computer equipment. According to the method, the internal resistance values of the standard internal resistance curve and the internal resistance curve to be detected under the same SOC value can be utilized to perform curve normalization, so that each internal resistance value of the internal resistance curve to be detected and each internal resistance value of the standard internal resistance curve can be reasonably mapped to the same value interval under the condition that the curve trend is not influenced. As the normalized standard curve reflects the change trend of the internal resistance of the lithium battery under the condition that the lithium precipitation phenomenon does not occur, even if the internal resistance value of the lithium battery is in a decreasing trend in the whole charging process, the internal resistance value of the lithium battery can be calculated by comparing the change trend of the internal resistance of the normalized detection curve and the change trend of the internal resistance of the normalized standard curve. And the lithium precipitation inflection point of the internal resistance curve to be detected is accurately determined, so that the technical defect that the lithium precipitation inflection point of the lithium battery cannot be detected in the prior art can be overcome, and the detection accuracy of the lithium precipitation inflection point of the lithium battery can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to a method, device, storage medium, and computer device for detecting the lithium plating inflection point. Background Art

[0002] Lithium batteries are widely used in electric vehicles due to their advantages such as high power density, long life, and environmental protection. In recent years, driven by the demand for high-performance electric vehicles, significant progress has been made in the energy density and life of lithium batteries. However, lithium battery safety accidents occur from time to time, threatening the lives and property safety of users. According to the statistics of electric vehicle fire accidents, charging-related safety accidents account for nearly 23% of the total number of accidents, with the largest proportion. This is because during overcharging, fast charging, and low-temperature charging, lithium plating is likely to occur inside the lithium battery, resulting in the growth of lithium dendrites, poor thermal stability, and ultimately increasing the risk of lithium battery thermal runaway. Thus, accurate detection of lithium plating is one of the keys to ensuring the charging safety of lithium batteries.

[0003] Currently, existing lithium plating detection methods include: methods based on differential discharge voltage analysis, methods based on voltage relaxation curves, and methods based on impedance. Among them, the first two methods are post-detection methods for the lithium plating process, which can only reflect the lithium plating situation of the lithium battery in the last charging stage and cannot effectively monitor the lithium plating inflection point of the lithium battery. For example, when the state of charge (SOC) of a lithium battery is charged from 0% to 100%, if lithium plating starts when the SOC = 65%, the methods based on differential discharge voltage analysis and methods based on voltage relaxation curves can only determine whether lithium plating occurs when the SOC = 100%, but cannot detect the node where the lithium plating behavior starts, that is, cannot determine the lithium plating inflection point.

[0004] For example, the impedance-based method provided by CN117192405A uses the principle that the overall impedance on the negative electrode surface of the battery decreases when lithium plating occurs, and judges the lithium plating inflection point through the sudden drop point of the impedance. However, the impedance of some lithium batteries shows a downward trend throughout the charging process, and it is difficult for the existing technology to accurately track the change trend of the impedance curve, and thus the lithium plating inflection point of this kind of lithium battery cannot be detected.

[0005] Therefore, there is an urgent need to provide a solution that can accurately detect the lithium plating inflection point. Summary of the Invention

[0006] The purpose of the present application aims to at least solve one of the above technical defects, especially the technical defect that the lithium plating inflection point of a lithium battery cannot be accurately detected in the prior art.

[0007] In a first aspect, an embodiment of the present application provides a method for detecting the lithium plating inflection point, including:

[0008] Obtain the standard internal resistance curve and the internal resistance curve to be detected of the lithium battery; wherein, the standard internal resistance curve is a curve obtained by charging the lithium battery at a first non-lithium-plating charging rate.

[0009] According to the internal resistance value corresponding to the preset SOC value in the standard internal resistance curve, perform normalization processing on the standard internal resistance curve and obtain a normalized standard curve.

[0010] According to the internal resistance value corresponding to the preset SOC value in the internal resistance curve to be detected, perform normalization processing on the internal resistance curve to be detected and obtain a normalized detection curve.

[0011] If the preset judgment rule is satisfied, then based on the deviation of the normalized detection curve from the normalized standard curve, detect the lithium-plating inflection point SOC value of the internal resistance curve to be detected.

[0012] In some embodiments, the number of the preset SOC values is N, and the number of the normalized standard curves and the number of the normalized detection curves are both N, where N is a positive integer greater than 1.

[0013] The detecting the lithium-plating inflection point SOC value of the internal resistance curve to be detected based on the deviation of the normalized detection curve from the normalized standard curve includes:

[0014] According to the deviation of the target detection curve from the target standard curve, determine the initial inflection point SOC value of the internal resistance curve to be detected at the target SOC value; wherein, the target detection curve is a normalized detection curve obtained by performing normalization processing based on the target SOC value, the target standard curve is a normalized standard curve obtained by performing normalization processing based on the target SOC value, and the target SOC value is any one of the N preset SOC values.

[0015] Adopt a preset inflection point screening rule to screen out M candidate SOC values from the N initial inflection point SOC values; wherein, M ≤ N.

[0016] Take the minimum value of the M candidate SOC values as the lithium-plating inflection point SOC value.

[0017] In some embodiments, the adopting a preset inflection point screening rule to screen out M candidate SOC values from the N initial inflection point SOC values includes:

[0018] Compare the curve trend of the first curve segment of the target detection curve with the curve trend of the second curve segment of the target standard curve; wherein, the first curve segment is the curve segment of the target detection curve where the SOC value is less than or equal to the target inflection point SOC value, the second curve segment is the curve segment of the target standard curve where the SOC value is less than or equal to the target inflection point SOC value, and the target inflection point SOC value is the initial inflection point SOC value corresponding to the target SOC value of the internal resistance curve to be detected;

[0019] If the curve trend of the first curve segment is consistent with the curve trend of the second curve segment, then use the target inflection point SOC value as the candidate SOC value; otherwise, exclude the target inflection point SOC value.

[0020] In some embodiments, detecting the lithium plating inflection point SOC value of the internal resistance curve to be detected based on the deviation of the normalized detection curve from the normalized standard curve includes:

[0021] Calculate the first internal resistance difference and the second internal resistance difference of the normalized detection curve at each SOC value to be detected; wherein, the first internal resistance difference is the internal resistance difference between the normalized detection curve and the normalized standard curve at the SOC value to be detected, and the second internal resistance difference is the internal resistance difference corresponding to two adjacent SOC values to be detected;

[0022] Determine the lithium plating inflection point SOC value among the SOC values to be detected according to each of the first internal resistance differences and each of the second internal resistance differences.

[0023] In some embodiments, determining the lithium plating inflection point SOC value among the SOC values to be detected according to each of the first internal resistance differences and each of the second internal resistance differences includes:

[0024] If the first internal resistance difference corresponding to the SOC value to be judged is greater than the first preset threshold, and the absolute value of the second internal resistance difference corresponding to the SOC value to be judged is greater than the second preset threshold, then use the SOC value to be judged as the lithium plating inflection point SOC value; otherwise, do not use the SOC value to be judged as the lithium plating inflection point SOC value;

[0025] Wherein, the SOC value to be judged is any one of the SOC values to be detected.

[0026] In some embodiments, the judgment steps of the preset judgment rule include:

[0027] Obtain the calibration internal resistance curve of the lithium battery; wherein, the calibration internal resistance curve is the curve obtained by charging the lithium battery at a second non-lithium plating charging rate, and the second non-lithium plating charging rate is greater than the first non-lithium plating charging rate;

[0028] According to the internal resistance value corresponding to the preset SOC value in the calibration internal resistance curve, normalize the calibration internal resistance curve to obtain a normalized calibration curve;

[0029] If the curve trend of the normalized calibration curve is consistent with the curve trend of the normalized standard curve, it is determined that the preset judgment rule is satisfied.

[0030] In some embodiments, the constant volume capacity of the lithium battery is C 0 ;

[0031] If the charging temperature of the lithium battery is 30°C to 45°C, the second non-lithium-plating charging rate is 0.5C 0 ~1C 0 ;

[0032] If the charging temperature of the lithium battery is 25°C to 30°C, the second non-lithium-plating charging rate is 0.5C 0 ~0.8C 0 ;

[0033] If the charging temperature of the lithium battery is 10°C to 25°C, the second non-lithium-plating charging rate is 0.2C 0 ~0.5C 0 ;

[0034] If the charging temperature of the lithium battery is 0°C to 10°C, the second non-lithium-plating charging rate is 0.1C 0 ~0.3C 0 ;

[0035] If the charging temperature of the lithium battery is -10°C to 0°C, the second non-lithium-plating charging rate is 0.1C 0 ~0.2C 0 ;

[0036] If the charging temperature of the lithium battery is -20°C to -10°C, the second non-lithium-plating charging rate is 0.05C 0 ~0.08C 0 。

[0037] In some embodiments, the preset SOC value is greater than 0% and less than or equal to 20%.

[0038] Second, the embodiments of the present application provide a lithium plating inflection point detection device, including:

[0039] A curve acquisition module for acquiring a standard internal resistance curve and a to-be-detected internal resistance curve of a lithium battery; wherein, the standard internal resistance curve is a curve obtained by charging the lithium battery with a first non-lithium-plating charging rate;

[0040] The first normalization processing module is configured to perform normalization processing on the standard internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the standard internal resistance curve, and obtain a normalized standard curve;

[0041] The second normalization processing module is configured to perform normalization processing on the to-be-detected internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the to-be-detected internal resistance curve, and obtain a normalized detection curve;

[0042] The lithium plating inflection point detection module is configured to, if a preset judgment rule is satisfied, detect the lithium plating inflection point SOC value of the to-be-detected internal resistance curve based on the deviation of the normalized detection curve from the normalized standard curve.

[0043] In a third aspect, an embodiment of the present application provides a computer device, which includes: one or more processors, and a memory;

[0044] Computer-readable instructions are stored in the memory, and when the computer-readable instructions are executed by the one or more processors, the steps of the lithium plating inflection point detection method described in any of the above embodiments are executed.

[0045] In the lithium plating inflection point detection method, device, storage medium, and computer device provided in some embodiments of the present application, the standard internal resistance curve can be normalized according to the internal resistance value at the preset SOC value, and a normalized standard curve can be obtained. And, the to-be-detected internal resistance curve can be normalized according to the internal resistance value at the same SOC value, and a normalized detection curve can be obtained. In this way, by using the internal resistance value of the internal resistance curve itself for normalization, the internal resistance values of the to-be-detected internal resistance curve and the internal resistance values of the standard internal resistance curve can be reasonably mapped to the same value range without affecting the curve trend.

[0046] Since the standard internal resistance curve is the internal resistance curve corresponding to the non-lithium-plating charging rate, the normalized standard curve can reflect the change trend of the lithium battery internal resistance without lithium plating. By comparing the internal resistance change trends of the normalized detection curve and the normalized standard curve, the lithium plating inflection point SOC value of the to-be-detected internal resistance curve can be determined according to the deviation of the normalized detection curve from the normalized standard curve. In this way, even if the internal resistance value of the lithium battery shows a downward trend throughout the charging process, the present application can accurately determine the lithium plating inflection point SOC value through curve trend comparison, thereby making up for the technical defect that the prior art cannot detect the lithium plating inflection point of the aforementioned type of lithium battery, and further improving the detection accuracy of the lithium plating inflection point of the lithium battery. Description of the Drawings

[0047] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0048] Figure 1 In some embodiments, it is a schematic flowchart of a method for detecting the lithium plating inflection point.

[0049] Figure 2 In some embodiments, it is the internal resistance curve of a lithium battery at different charging rates.

[0050] Figure 3 In some embodiments, it is the voltage change of a lithium battery during a single charging and resting cycle.

[0051] Figure 4 In some embodiments, it is the current change of a lithium battery during a single charging and resting cycle.

[0052] Figure 5 Taking 5% as the preset SOC value, for Figure 2 The result of normalization processing.

[0053] Figure 6 Taking 10% as the preset SOC value, for Figure 2 The result of normalization processing.

[0054] Figure 7 Taking 15% as the preset SOC value, for Figure 2 The result of normalization processing.

[0055] Figure 8 Taking 50% as the preset SOC value, for Figure 2 The result of normalization processing.

[0056] Figure 9 In some embodiments, it is a schematic flowchart of the steps for detecting the lithium plating inflection point SOC value of the internal resistance curve to be detected.

[0057] Figure 10 In some embodiments, it is a schematic structural diagram of a lithium plating inflection point detection device.

[0058] Figure 11 In some embodiments, it is the internal structure diagram of a computer device. Detailed implementation manners

[0059] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0060] In some embodiments, the embodiments of the present application provide a method for detecting the lithium plating inflection point. The following embodiments are described by taking the application of this method to a computer device as an example. It can be understood that the computer device described in the present application can be any device with data acquisition function and data processing function, and can be, but is not limited to, a tablet computer, a notebook computer, a laptop computer, a desktop computer, a smart phone, a wearable device, an Internet of Things device, a server cluster composed of one or more servers, etc.

[0061] As Figure 1 shown, the method for detecting the lithium plating inflection point provided by the present application may include the following steps:

[0062] S102: Obtain the standard internal resistance curve and the internal resistance curve to be detected of the lithium battery.

[0063] Among them, the first non-lithium-plating charging rate refers to the charging rate that will not or hardly cause lithium plating in the lithium battery, and it can be determined according to actual situations such as battery temperature and battery type. The standard internal resistance curve is the internal resistance curve obtained by charging the lithium battery at the first non-lithium-plating charging rate, which can reflect the change of the internal resistance value of the lithium battery with the state of charge during the charging process of the lithium battery at the first non-lithium-plating charging rate.

[0064] The internal resistance curve to be detected is the internal resistance curve obtained by charging the lithium battery at the target charging rate, which can reflect the change of the internal resistance value of the lithium battery with the state of charge during the charging process of the lithium battery at the target charging rate. The target charging rate is greater than the first non-lithium-plating charging rate, and the target charging rate can be the charging rate for which the lithium plating inflection point needs to be determined, and its specific value can be determined according to actual situations. The target charging rate can be formulated according to the fast charging requirement, and the present application does not make specific limitations on this. For example, the target charging rate can be 1C, 2C, 4C, 5C, 6C, 7C, 8C, etc., where C is the ratio of the current magnitude for the battery to be fully charged or discharged within 1 hour to the rated capacity of the lithium battery.

[0065] It can be understood that the abscissa of the standard internal resistance curve and the abscissa of the internal resistance curve to be detected are of the same index dimension, and the ordinate of the standard internal resistance curve and the ordinate of the internal resistance curve to be detected are of the same index dimension. In some examples, the abscissas of both the standard internal resistance curve and the internal resistance curve to be detected can be internal resistance values, and the ordinates can both be SOC values. In other examples, the abscissas of both the standard internal resistance curve and the internal resistance curve to be detected can be SOC values, and the ordinates can both be internal resistance values. For ease of description, in the embodiments of this application, an example where the abscissa is the SOC value and the ordinate is the internal resistance value is used for description.

[0066] In this step, the standard internal resistance curve and the internal resistance curve to be detected can be obtained respectively. For example, Figure 2 shows the internal resistance curves of the battery at 5 different charging rates, and the 5 charging rates are 0.1C, 0.2C, 0.5C, 0.8C, and 1C respectively. In Figure 2 the example, the standard internal resistance curve can be the internal resistance curve corresponding to 0.1C, and the internal resistance curves to be detected can be the internal resistance curves corresponding to 0.2C, 0.5C, 0.8C, and / or 1C.

[0067] It should be noted that the standard internal resistance curve and the internal resistance curve to be detected can adopt any measurement method and be measured by a battery internal resistance measurement device. This application does not make specific restrictions on this. The computer device described in this application can be a component of the battery internal resistance measurement device or a device independent of the battery internal resistance measurement device. This application does not make specific restrictions on this.

[0068] In some examples, taking the measurement of the standard internal resistance curve as an example, the battery internal resistance measurement device can charge the lithium battery at a first non-lithium-plating charging rate, and for every n% SOC charged, it stands still for m seconds, and charges the SOC of the lithium battery to 100% through multiple charging and standing cycles. Among them, both n and m are preset positive integers. For example, if n = 5 and m = 10, then when the SOC of the lithium battery is charged to 5%, it stands still for 10 seconds. After standing still for 10 seconds, the SOC of the lithium battery is charged to 10%, and then stands still for 10 seconds. After the second standing still, the SOC of the lithium battery is charged to 15%, and then stands still for 10 seconds, and so on until the SOC of the lithium battery reaches 100%.

[0069] The battery internal resistance measurement device can calculate the internal resistance value R of the lithium battery at the corresponding SOC value according to the voltage change value △V and the current change value △I before and after the same standing still by using R = △V / △I. Please refer to Figure 3 and Figure 4, the voltage change value △V can be the difference between the last voltage during charging and the last voltage during rest in the current charging and rest cycle of the lithium battery, and the current change value △I can be the difference between the last current during charging and the last current during rest in the current charging and rest cycle of the lithium battery. Ideally, the current during rest is strictly 0, but there will be measurement errors or the problem of the charging current decreasing during actual rest. Therefore, calculating the current interpolation can more accurately reflect the actual current change. At the same time, after the current returns to zero, the ohmic polarization disappears instantly (at the microsecond level), which can greatly relieve the concentration polarization. Since the further charging current is low, the polarization effect can be further reduced and the measurement accuracy can be improved.

[0070] In the above example where n = 5 and m = 10, when the SOC of the lithium battery is charged from 0% to 5%, the battery internal resistance measurement device can respectively collect the last first voltage V1 and the last first current I1 of the lithium battery at SOC = 5% and rest for 10 seconds. Before the end of the rest, the battery internal resistance measurement device can respectively collect the last voltage V2 and the last current I2 of the lithium battery during the rest, and calculate the internal resistance value of the lithium battery at SOC = 5% according to △V = V1 - V2, △I = I1 - I2, and R = △V / △I.

[0071] S104: Normalize the standard internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the standard internal resistance curve, and obtain a normalized standard curve.

[0072] Specifically, from Figure 2 It can be seen that under different charging rates, the value ranges of the internal resistance values of lithium batteries are different. It is difficult to directly compare the standard internal resistance curve with the internal resistance curve to be detected, and accurate results cannot be obtained. Therefore, this application performs curve normalization on the internal resistance curve and obtains a normalized curve.

[0073] In this step, the internal resistance values of the standard internal resistance curve can be normalized according to the internal resistance value of the standard internal resistance curve at the preset SOC value, so as to obtain a normalized standard curve. It should be noted that the number of preset SOC values can be one or more, and its number can be determined according to the actual situation. This application does not make specific restrictions on this.

[0074] When there is one preset SOC value, the present application can use the internal resistance value of the standard internal resistance curve at the preset SOC value as the normalization standard value, and normalize the standard internal resistance curve according to the method of internal resistance value / normalization standard value, so as to obtain the normalized standard curve. For example, if the preset SOC value is 10%, the internal resistance value of the standard internal resistance curve at SOC = 10% can be used as the normalization standard value R1. When normalizing the internal resistance value at SOC = 5%, the ratio of the actual internal resistance value R2 of the standard internal resistance curve at SOC = 5% to the normalization standard value R1 can be used as the normalized internal resistance value corresponding to SOC = 5%. That is, in the normalized standard curve, the internal resistance value corresponding to SOC = 5% is R2 / R1.

[0075] When there are multiple preset SOC values, the present application can respectively use the internal resistance values of the standard internal resistance curve at each preset SOC value as the normalization standard values, and perform normalization processing accordingly, so as to obtain the normalized standard curves corresponding to each preset SOC value. For example, if the preset SOC values are 10% and 30% respectively, the present application can use the internal resistance value of the standard internal resistance curve at SOC = 10% as the normalization standard value, perform normalization calculation on each internal resistance value of the standard internal resistance curve, and obtain the first normalized standard curve corresponding to SOC = 10%. Moreover, the present application can also use the internal resistance value of the standard internal resistance curve at SOC = 30% as the normalization standard value, perform normalization calculation on each internal resistance value of the standard internal resistance curve, and obtain the second normalized standard curve corresponding to SOC = 30%. The specific normalization calculation process can refer to the description above, and the present application will not elaborate here.

[0076] S106: Normalize the to-be-detected internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the to-be-detected internal resistance curve, and obtain the normalized detection curve.

[0077] In this step, the normalization calculation can be performed on each internal resistance value of the to-be-detected internal resistance curve according to the internal resistance value of the to-be-detected internal resistance curve at the preset SOC value, so as to obtain the normalized detection curve. The relevant descriptions of the preset SOC value and the normalization calculation can refer to the description of the normalized standard curve above, and the present application will not elaborate here.

[0078] Exemplarily, Figure 5 shows the results after normalizing each internal resistance curve shown Figure 2 with 5% as the preset SOC value. Figure 6 shows the results after normalizing each internal resistance curve shown Figure 2 with 10% as the preset SOC value. Figure 7 shows the results after normalizing each internal resistance curve shown Figure 2 with 15% as the preset SOC value. Figure 8shows the result after normalizing each of the internal resistance curves shown with 50% as the preset SOC value. Figure 2

[0079] S108: If the preset judgment rule is satisfied, then based on the deviation of the normalized detection curve from the normalized standard curve, detect the lithium plating inflection point SOC value of the internal resistance curve to be detected.

[0080] Among them, the preset judgment rule refers to the rule used to judge whether to determine the lithium plating inflection point according to the normalized detection curve and the normalized standard curve, and its specific rule content can be determined according to the actual situation. The lithium plating inflection point SOC value refers to the SOC value corresponding to when the lithium battery starts to plate lithium. The deviation of the normalized detection curve from the normalized standard curve refers to the situation where the normalized detection curve deviates from the benchmark with the normalized standard curve as the benchmark.

[0081] The internal resistance change trend of the lithium battery after lithium plating is different from that of the lithium battery without lithium plating. Therefore, the present application can compare the internal resistance change trend of the lithium battery at the first non-lithium plating charging rate with the internal resistance change trend of the lithium battery at the target charging rate, and determine the deviation of the normalized detection curve from the normalized standard curve, thereby obtaining the lithium plating inflection point SOC value of the lithium battery at the target charging rate.

[0082] The present application can normalize using the internal resistance values of the internal resistance curve itself, so that without affecting the curve trend, the internal resistance values of the internal resistance curve to be detected and the internal resistance values of the standard internal resistance curve can be reasonably mapped to the same value range. Since different charge and discharge rates will affect the electrochemical reaction rate and polarization degree inside the battery, through the above normalization process, the internal resistance curves at different charging rates can be unified to the same numerical range, so as to more intuitively compare the internal resistance change trends at different rates. For example, under low temperature conditions, the internal resistance curves of the battery at different charging rates may be difficult to directly compare due to the difference in numerical ranges. Through the present application, the lithium plating inflection point can be more clearly reflected. At the same time, in actual tests, the data will fluctuate or data will be missing due to measurement errors, environmental factors, temperature effects, etc. The normalization process can smooth these fluctuations and make the data more stable, thereby improving the accuracy of detecting the lithium plating inflection point. By comparing the internal resistance change trends of the normalized detection curve and the normalized standard curve, the present application can determine the lithium plating inflection point SOC value of the internal resistance curve to be detected according to the deviation of the normalized detection curve from the normalized standard curve. In this way, even if the internal resistance value of the lithium battery shows a downward trend throughout the charging process, the present application can accurately determine the lithium plating inflection point SOC value through curve trend comparison, thereby making up for the technical defect that the prior art cannot detect the lithium plating inflection point of the aforementioned type of lithium battery, and further improving the detection accuracy of the lithium plating inflection point of the lithium battery.

[0083] ​Meanwhile, the present application has the advantages of convenient use and is easily coupled with the battery charge and discharge program. Thus, it is convenient to adjust the battery charge and discharge program when determining the lithium plating node, prevent lithium plating behavior on the surface of the battery negative electrode, thereby improving the overall safety performance of the battery, and can hinder the loss of active substances and interface degradation, and improve the service life of the battery.

[0084] In some embodiments, the number of preset SOC values is N, and N is a positive integer greater than 1. In this case, the number of normalized standard curves is N, and the number of normalized detection curves is also N. For example, when N = 2 and the preset SOC values include a first SOC value and a second SOC value, the present application can respectively obtain a first normalized standard curve corresponding to the first SOC value, a second normalized standard curve corresponding to the second SOC value, a first normalized detection curve corresponding to the first SOC value, and a second normalized standard curve corresponding to the second SOC value.

[0085] As Figure 9 shown, based on the deviation of the normalized detection curve from the normalized standard curve, detecting the lithium plating inflection point SOC value of the internal resistance curve to be detected includes:

[0086] S202: Determine the initial inflection point SOC value of the internal resistance curve to be detected at the target SOC value according to the deviation of the target detection curve from the target standard curve.

[0087] Wherein, the target detection curve is a normalized detection curve obtained by normalizing based on the target SOC value, the target standard curve is a normalized standard curve obtained by normalizing based on the target SOC value, and the target SOC value is any one of the N preset SOC values.

[0088] Specifically, in the case where there are multiple preset SOC values, the present application can respectively use the normalized standard curve and the normalized detection curve corresponding to the same preset SOC value as the target detection curve and the target standard curve, and compare the internal resistance change trend of the target detection curve with the internal resistance change trend of the target standard curve, thereby determining the deviation of the target detection curve from the target standard curve, and further determining the lithium plating inflection point of the internal resistance curve to be detected at this preset SOC value, and obtaining the initial inflection point SOC value corresponding to this preset SOC value.

[0089] For example, in the above example where N = 2, the computer device can compare the curve trends of the first normalized standard curve and the first normalized detection curve, and determine the lithium plating inflection point of the internal resistance curve to be detected at the first SOC value based on the deviation of the first normalized detection curve from the first normalized standard curve, so as to obtain the initial inflection point SOC value corresponding to the first SOC value. Similarly, the computer device can compare the curve trends of the second normalized standard curve and the second normalized detection curve, and determine the lithium plating inflection point of the internal resistance curve to be detected at the second SOC value based on the deviation of the second normalized detection curve from the second normalized standard curve, so as to obtain the initial inflection point SOC value corresponding to the second SOC value.

[0090] For another example, in Figures 5 to 8 the example shown, if the preset SOC value is 5%, the initial inflection point SOC value corresponding to 0.5C is 75%, the initial inflection point SOC value corresponding to 0.8C is 55%, and the initial inflection point SOC value corresponding to 1C is 45%. If the preset SOC value is 10%, the initial inflection point SOC value corresponding to 0.5C is 75%, the initial inflection point SOC value corresponding to 0.8C is 50%, and the initial inflection point SOC value corresponding to 1C is 45%. If the preset SOC value is 15%, the initial inflection point SOC value corresponding to 0.5C is 75%, the initial inflection point SOC value corresponding to 0.8C is 50%, and the initial inflection point SOC value corresponding to 1C is 45%. If the preset SOC value is 50%, the initial inflection point SOC value corresponding to 0.5C is 75%, the initial inflection point SOC value corresponding to 0.8C is 55%, and the initial inflection point SOC value corresponding to 1C is 55%.

[0091] S204: Using a preset inflection point screening rule, screen out M candidate SOC values from the N initial inflection point SOC values; where M ≤ N.

[0092] Among them, the content of the inflection point screening rule can be set in advance according to the actual situation. The computer device can screen the N initial inflection point SOC values according to the preset inflection point screening rule to exclude the initial inflection point SOC values that do not meet the inflection point screening rule, and use the M inflection point screening SOC values that meet the inflection point screening rule as candidate SOC values.

[0093] S206: Take the minimum value among the M candidate SOC values as the lithium plating inflection point SOC value.

[0094] That is, among the normalized detection curves at different preset SOCs with the same target charging rate, select the minimum value among the inflection point SOC values as the final lithium plating inflection point. For example, in Figures 5 to 8In the example shown, if the internal resistance curve to be detected is the internal resistance curve corresponding to 1C, the SOC values of the 4 initial inflection points are 45%, 45%, 45%, and 55% respectively. If the SOC values of the aforementioned 4 initial inflection points are all candidate SOC values, the computer device can use the minimum value of 45% as the lithium plating inflection point SOC value of the lithium battery at a charging rate of 1C.

[0095] In this embodiment, curve normalization processing is performed based on multiple preset SOC values, and multiple initial inflection point SOC values are screened. The minimum value among the M candidate SOC values obtained by screening is used as the lithium plating inflection point at the target charging rate. That is, the lithium plating inflection points at different target charging rates can be output, so as to determine the charging strategy according to different charging rates. Adjusting the charging and discharging degree of the lithium battery according to the lithium plating inflection point determined in this embodiment can effectively reduce the probability of lithium plating in the lithium battery, and thus improve the safety of the lithium battery.

[0096] In some embodiments, using a preset inflection point screening rule, M candidate SOC values are screened out from N initial inflection point SOC values, including:

[0097] Step A2: Compare the curve trend of the first curve segment of the target detection curve with the curve trend of the second curve segment of the target standard curve; wherein, the first curve segment is the curve segment of the target detection curve where the SOC value is less than or equal to the target inflection point SOC value, and the second curve segment is the curve segment of the target standard curve where the SOC value is less than or equal to the target inflection point SOC value, and the target inflection point SOC value is the initial inflection point SOC value corresponding to the target SOC value of the internal resistance curve to be detected;

[0098] Step A4: If the curve trend of the first curve segment is consistent with the curve trend of the second curve segment, then use the target inflection point SOC value as the candidate SOC value, otherwise, exclude the target inflection point SOC value.

[0099] Specifically, when the lithium battery does not undergo lithium plating, the curve trend of the normalized detection curve should be consistent with the curve trend of the normalized standard curve. However, in the case of improper selection of the preset SOC value, even if the lithium battery does not undergo lithium plating, the curve trend of the normalized detection curve and the curve trend of the normalized standard curve may be different. This will affect the detection accuracy of the lithium plating inflection point SOC value. Therefore, such curves need to be excluded to further improve the detection accuracy of the lithium plating inflection point.

[0100] In this embodiment, the computer device can use the normalized standard curve and the normalized detection curve corresponding to the same preset SOC value as the target detection curve and the target standard curve respectively, and determine the initial inflection point SOC value of the internal resistance curve to be detected at this preset SOC value according to the deviation of the target detection curve from the target standard curve. This initial inflection point SOC value is the target inflection point SOC value.

[0101] The computer device can use the curve segment of the target detection curve where the SOC value is less than the target inflection point SOC value as the first curve segment, and the first curve segment reflects the internal resistance change trend of the lithium battery when no lithium plating occurs. The computer device can use the curve segment of the target standard curve where the SOC value is less than the target inflection point SOC value as the second curve segment, and compare the trends of the first curve segment and the second curve segment to determine whether the first curve segment and the second curve segment have consistent curve trends.

[0102] If the curve trend of the first curve segment is inconsistent with the curve trend of the second curve segment, it indicates that the preset SOC value is not properly selected, and the curve trend of the target detection curve cannot reflect the actual change of the internal resistance value of the lithium battery. To avoid interference of the target detection curve on the lithium plating judgment, the computer device can exclude the initial inflection point SOC value corresponding to the target detection curve.

[0103] Conversely, if the curve trend of the first curve segment is consistent with the curve trend of the second curve segment, it indicates that the curve trend of the target detection curve can reflect the actual change of the internal resistance value of the lithium battery. Therefore, the initial inflection point SOC value corresponding to the target detection curve can be used as the candidate SOC value.

[0104] In some embodiments, based on the deviation of the normalized detection curve from the normalized standard curve, detecting the lithium plating inflection point SOC value of the internal resistance curve to be detected includes:

[0105] Step B2: Calculate the first internal resistance difference and the second internal resistance difference of the normalized detection curve at each SOC value to be detected; where the first internal resistance difference is the internal resistance difference between the normalized detection curve and the normalized standard curve at the SOC value to be detected, and the second internal resistance difference is the internal resistance difference corresponding to two adjacent SOC values to be detected of the normalized detection curve;

[0106] Step B4: Determine the lithium plating inflection point SOC value among the SOC values to be detected according to each first internal resistance difference and each second internal resistance difference.

[0107] In this embodiment, the lithium plating inflection point SOC value of the internal resistance curve to be detected can be jointly determined according to the internal resistance difference between the normalized detection curve and the normalized standard curve, and the internal resistance difference of the normalized detection curve at adjacent SOC values. In this way, the lithium plating inflection point can be jointly determined based on the comparison result between the normalized detection curve and the normalized standard curve, and the comparison result of the normalized detection curve itself, thereby further improving the detection accuracy.

[0108] Specifically, the SOC value to be detected refers to the SOC value for which the internal resistance difference needs to be calculated, and its quantity and specific SOC values can be determined according to the actual situation, and this application does not make specific restrictions on this.

[0109] For the i-th SOC value to be detected, the present application can respectively determine the internal resistance value R3 of each normalized detection curve at the i-th SOC value to be detected, the internal resistance value R4 of the normalized standard curve at the i-th SOC value to be detected, and the internal resistance value R5 of the normalized detection curve at the (i + 1)-th SOC value to be detected, and use the result of (R3 - R4) as the first internal resistance difference of the normalized detection curve at the i-th SOC value to be detected, and use the result of (R3 - R5) as the second internal resistance difference of the normalized detection curve at the i-th SOC value to be detected. Here, i refers to the arrangement order corresponding to the SOC value to be detected after sorting each SOC value to be detected in ascending order.

[0110] Exemplarily, in Figures 5 to 8 the example of, the SOC values to be detected can be 5%, 10%, 15%, 20%, 25%, …… 100%. Among them, 5% is the 1st SOC value to be detected, 10% is the 2nd SOC value to be detected, 15% is the 3rd SOC value to be detected, and so on. When calculating the internal resistance difference corresponding to SOC = 5%, first, the internal resistance value R 检测|SOC=5% of the normalized detection curve at SOC = 5% and the internal resistance value R 检测|SOC=10% of the normalized detection curve at SOC = 10% and the internal resistance value R 标准|SOC=5% of the normalized standard curve at SOC = 5% can be respectively determined, and the difference between R 检测|SOC=5% and R 标准|SOC=5% is used as the first internal resistance difference corresponding to SOC = 5%, and the difference between R 检测|SOC=5% and R 检测|SOC=10% is used as the second internal resistance difference corresponding to SOC = 5%.

[0111] In the case of determining the first internal resistance difference and the second internal resistance difference corresponding to each SOC value to be detected, the present application can determine the lithium plating inflection point SOC value of the internal resistance curve to be detected based on each first internal resistance difference and each second internal resistance difference.

[0112] In some embodiments, determining the lithium plating inflection point SOC value among each SOC value to be detected according to each first internal resistance difference and each second internal resistance difference includes:

[0113] If the first internal resistance difference corresponding to the SOC value to be judged is greater than the first preset threshold, and the absolute value of the second internal resistance difference corresponding to the SOC value to be judged is greater than the second preset threshold, then the SOC value to be judged is used as the lithium plating inflection point SOC value, otherwise, the SOC value to be judged is not used as the lithium plating inflection point SOC value;

[0114] Here, the SOC value to be judged is any one of each SOC value to be detected.

[0115] In this embodiment, for each SOC value to be detected on each normalized detection curve, the present application can compare the first internal resistance difference corresponding to the SOC value to be detected with the first preset threshold, and compare the absolute value of the second internal resistance difference corresponding to the SOC value to be detected with the second preset threshold, and determine whether the SOC value to be detected on the normalized detection curve is the lithium plating inflection point SOC value based on the comparison result. In this way, the detection efficiency of the lithium plating inflection point can be improved while ensuring the detection accuracy of the lithium plating inflection point.

[0116] For the same SOC value to be detected, the comparison result can be one of the following four cases:

[0117] (1) If the first internal resistance difference is greater than the first preset threshold and the absolute value of the second internal resistance difference is greater than the second preset threshold, the SOC value to be detected can be determined as the lithium plating inflection point SOC value;

[0118] (2) If the first internal resistance difference is less than or equal to the first preset threshold and the absolute value of the second internal resistance difference is less than or equal to the second preset threshold, it can be determined that the lithium battery does not plate lithium at the SOC value to be detected. Therefore, the SOC value to be detected is not used as the lithium plating inflection point SOC value;

[0119] (3) If the first internal resistance difference is less than or equal to the first preset threshold and the absolute value of the second internal resistance difference is greater than the second preset threshold, the SOC value to be detected is a jitter point, and the SOC value to be detected is not used as the lithium plating inflection point SOC value;

[0120] (4) If the first internal resistance difference is greater than the first preset threshold and the absolute value of the second internal resistance difference is less than or equal to the second preset threshold, the SOC value to be detected is a jitter point, and the SOC value to be detected is not used as the lithium plating inflection point SOC value.

[0121] It can be understood that the first preset threshold and the second preset threshold can be determined according to the normalized standard curve. Specifically, the internal resistance interpolation values of the two normalized standard curves at the same SOC value to be detected can be determined respectively, and the maximum value among them is selected as the first preset threshold. For example, if the maximum value of the internal resistance differences of the two normalized standard curves at the same SOC value to be detected is 0.016, the first preset threshold is 0.016. Preferably, the first preset threshold can also be set to 0.02 to appropriately expand the range and improve the evaluation applicability. Further, the internal resistance differences between adjacent SOC values in the normalized standard curve with the smallest charging rate can be calculated, and the maximum value among them is selected as the second preset threshold. For example, on the normalized standard curve with a charging rate of 0.1C, the maximum value of the internal resistance differences between adjacent SOC values is 0.073, then the second preset threshold is set to 0.073. Preferably, the second preset threshold can also be set to 0.01 to appropriately expand the range and improve the evaluation applicability.

[0122] In some embodiments, the judgment steps of the preset judgment rule include:

[0123] Step C2: Obtain the calibration internal resistance curve of the lithium battery; wherein, the calibration internal resistance curve is a curve obtained by charging the lithium battery at a second non-lithium-plating charging rate, and the second non-lithium-plating charging rate is greater than the first non-lithium-plating charging rate;

[0124] Step C4: According to the internal resistance value corresponding to the preset SOC value in the calibration internal resistance curve, perform normalization processing on the calibration internal resistance curve to obtain a normalized calibration curve;

[0125] Step C6: If the curve trend of the normalized calibration curve is consistent with the curve trend of the normalized standard curve, it is determined that the preset judgment rule is satisfied.

[0126] Among them, the second non-lithium-plating charging rate refers to the charging rate that will not or hardly cause lithium plating in the lithium battery, and it can be determined according to actual situations such as battery temperature and battery type. This application does not make specific limitations on this. The calibration internal resistance curve is not the internal resistance curve obtained by charging the lithium battery at the second non-lithium-plating charging rate, and it can reflect the change of the internal resistance value of the lithium battery with the state of charge during the charging process of the lithium battery at the second non-lithium-plating charging rate.

[0127] In most cases, the higher the charging rate, the higher the probability of lithium plating. If the lithium battery does not undergo lithium plating at a higher charging rate, then the lithium battery also does not undergo lithium plating at a lower charging rate. Therefore, this embodiment can utilize this principle to verify whether the standard internal resistance curve is the internal resistance curve of the lithium battery under the condition of no lithium plating, thereby further improving the detection accuracy of the lithium plating inflection point.

[0128] In this embodiment, when the calibration internal resistance curve of the lithium battery is obtained, the internal resistance values of the calibration internal resistance curve can be normalized according to the internal resistance value at the preset SOC value, so as to obtain a normalized calibration curve. For the relevant descriptions of the preset SOC value and the normalization calculation, reference can be made to the above description of the normalized standard curve, and this application will not elaborate here.

[0129] After obtaining the normalized calibration curve, this application can compare the internal resistance change trend of the normalized calibration curve with the internal resistance change curve of the normalized standard curve to determine whether they have a consistent curve trend, and further verify whether the lithium battery does not undergo lithium plating throughout the entire charging cycle during the charging process at the first non-lithium-plating charging rate.

[0130] If the normalized verification curve and the normalized standard curve have the same curve trend, it indicates that during the charging process at the first non-lithium-plating charging rate, the lithium battery does not plate lithium throughout the entire charging cycle. Therefore, it can be determined that the preset judgment rule is satisfied, and the normalized standard curve can be used as the comparison benchmark to determine the lithium-plating inflection point. Conversely, if the curve trend of the normalized verification curve is inconsistent with that of the normalized standard curve, it is difficult to prove that the lithium battery does not plate lithium during the charging process at the first non-lithium-plating charging rate. In this case, it can be determined that the preset judgment rule is not satisfied, and the current normalized standard curve is not used as the comparison benchmark to determine the lithium-plating inflection point.

[0131] Furthermore, in some examples, if the curve trend of the normalized verification curve is inconsistent with that of the normalized standard curve, the present application can re-obtain the standard internal resistance curve and the calibrated internal resistance curve. Among them, the re-obtained standard internal resistance curve (hereinafter referred to as the second standard internal resistance curve) can be the internal resistance curve obtained by charging the lithium battery at the third non-lithium-plating charging rate, and the re-obtained verification internal resistance curve (hereinafter referred to as the second verification internal resistance curve) can be the internal resistance curve obtained by charging the lithium battery at the fourth non-lithium-plating charging rate. The third non-lithium-plating charging rate and the fourth non-lithium-plating charging rate are both less than the first non-lithium-plating charging rate, and the fourth non-lithium-plating charging rate is greater than the third non-lithium-plating charging rate.

[0132] The present application can perform normalization processing on the second standard internal resistance curve according to the above steps and obtain the third normalized standard curve. And, perform normalization processing on the second verification internal resistance curve according to the above steps and obtain the second normalized verification curve. If the curve trend of the second normalized verification curve is consistent with that of the third normalized standard curve, the third normalized standard curve is used as the benchmark to determine the lithium-plating inflection point.

[0133] In some embodiments, the constant volume capacity of the lithium battery is C 0 . It can be understood that the capacitance capacity of the lithium battery can be determined in any way, and the present application does not make specific restrictions on this. In some examples, the lithium battery can be fixed in volume by charging at a constant current and constant voltage of 0.33C, discharging at 0.33C, and cycling for 3 weeks at room temperature. During this process, the voltage range is 2.5V~3.65V, and the discharge capacity of the third week is taken as the constant volume capacity C 0 . For example, when the 100Ah battery cell is fixed in volume according to the foregoing method, its constant volume capacity can be obtained as 100.28Ah.

[0134] In this application, the first non-lithium-plating charging rate and the second non-lithium-plating charging rate can be selected according to the charging temperature to reduce the probability of lithium plating. In this way, it can be ensured as much as possible that both the standard internal resistance curve and the calibration internal resistance curve are the internal resistance curves of the lithium battery without lithium plating, without the need to re-obtain, re-process, and re-compare the standard internal resistance curve and the calibration internal resistance curve, thereby improving the detection efficiency of the lithium plating inflection point.

[0135] Specifically, if the charging temperature of the lithium battery is 30°C to 45°C, the second non-lithium-plating charging rate is 0.5C 0 ~1C 0 ; if the charging temperature of the lithium battery is 25°C to 30°C, the second non-lithium-plating charging rate is 0.5C 0 ~0.8C 0 ; if the charging temperature of the lithium battery is 10°C to 25°C, the second non-lithium-plating charging rate is 0.2C 0 ~0.5C 0 ; if the charging temperature of the lithium battery is 0°C to 10°C, the second non-lithium-plating charging rate is 0.1C 0 ~0.3C 0 ; if the charging temperature of the lithium battery is -10°C to 0°C, the second non-lithium-plating charging rate is 0.1C 0 ~0.2C 0 ; if the charging temperature of the lithium battery is -20°C to -10°C, the second non-lithium-plating charging rate is 0.05C 0 ~0.08C 0 .

[0136] As described in the above embodiments, when the preset SOC value is selected improperly, even if the lithium battery does not undergo lithium plating, the curve trend of the normalized detection curve may be different from the curve trend of the normalized standard curve, affecting the detection accuracy and detection efficiency of the lithium plating inflection point. To reduce the problems caused by the improper selection of the preset SOC value and improve the detection accuracy and detection efficiency, in some embodiments, the preset SOC value can be greater than 0% and less than or equal to 20%.

[0137] The lithium plating inflection point detection device provided by the embodiments of the present application will be described below. The lithium plating inflection point detection device described below can be correspondingly referred to the lithium plating inflection point detection method described above.

[0138] In some embodiments, as Figure 10 shown, the present application provides a lithium plating inflection point detection device 300, including:

[0139] A curve acquisition module 302, configured to acquire a standard internal resistance curve and a to-be-detected internal resistance curve of the lithium battery; wherein, the standard internal resistance curve is a curve obtained by charging the lithium battery at the first non-lithium-plating charging rate;

[0140] The first normalization processing module 304 is configured to normalize the standard internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the standard internal resistance curve, and obtain a normalized standard curve;

[0141] The second normalization processing module 306 is configured to normalize the to-be-detected internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the to-be-detected internal resistance curve, and obtain a normalized detection curve;

[0142] The lithium plating inflection point detection module 308 is configured to, if a preset judgment rule is satisfied, detect the lithium plating inflection point SOC value of the to-be-detected internal resistance curve based on the deviation of the normalized detection curve from the normalized standard curve.

[0143] In some embodiments, the number of the preset SOC values is N, the number of the normalized standard curves and the number of the normalized detection curves are both N, and N is a positive integer greater than 1. The lithium plating inflection point detection module 308 of the present application includes:

[0144] An initial inflection point determination unit is configured to determine the initial inflection point SOC value of the to-be-detected internal resistance curve at a target SOC value according to the deviation of a target detection curve from a target standard curve; wherein, the target detection curve is a normalized detection curve obtained by normalizing based on the target SOC value, the target standard curve is a normalized standard curve obtained by normalizing based on the target SOC value, and the target SOC value is any one of the N preset SOC values;

[0145] An inflection point screening unit is configured to screen out M candidate SOC values from the N initial inflection point SOC values by using a preset inflection point screening rule; wherein, M ≤ N;

[0146] A first lithium plating inflection point determination unit is configured to use the minimum value among the M candidate SOC values as the lithium plating inflection point SOC value.

[0147] In some embodiments, the inflection point screening unit of the present application includes:

[0148] A curve trend comparison unit is configured to compare the curve trend of a first curve segment of the target detection curve with that of a second curve segment of the target standard curve; wherein, the first curve segment is the curve segment of the target detection curve where the SOC value is less than or equal to the target inflection point SOC value, the second curve segment is the curve segment of the target standard curve where the SOC value is less than or equal to the target inflection point SOC value, and the target inflection point SOC value is the initial inflection point SOC value of the to-be-detected internal resistance curve corresponding to the target SOC value;

[0149] A candidate SOC value determination unit, configured to, if the curve trend of the first curve segment is consistent with the curve trend of the second curve segment, use the target inflection point SOC value as the candidate SOC value; otherwise, exclude the target inflection point SOC value.

[0150] In some embodiments, the lithium plating inflection point detection module 308 of the present application includes:

[0151] An internal resistance difference calculation unit, configured to calculate a first internal resistance difference and a second internal resistance difference of the normalized detection curve at each SOC value to be detected; wherein, the first internal resistance difference is the internal resistance difference between the normalized detection curve and the normalized standard curve at the SOC value to be detected, and the second internal resistance difference is the internal resistance difference corresponding to two adjacent SOC values to be detected;

[0152] A second lithium plating inflection point determination unit, configured to determine the lithium plating inflection point SOC value among the SOC values to be detected according to the first internal resistance differences and the second internal resistance differences.

[0153] In some embodiments, the second lithium plating inflection point determination unit of the present application includes:

[0154] An internal resistance difference comparison unit, configured to, if the first internal resistance difference corresponding to the SOC value to be judged is greater than a first preset threshold and the absolute value of the second internal resistance difference corresponding to the SOC value to be judged is greater than a second preset threshold, use the SOC value to be judged as the lithium plating inflection point SOC value; otherwise, do not use the SOC value to be judged as the lithium plating inflection point SOC value;

[0155] wherein, the SOC value to be judged is any one of the SOC values to be detected.

[0156] In some embodiments, the lithium plating inflection point detection device 300 of the present application further includes:

[0157] A calibration curve acquisition module, configured to acquire a calibration internal resistance curve of the lithium battery; wherein, the calibration internal resistance curve is a curve obtained by charging the lithium battery at a second non-lithium plating charging rate, and the second non-lithium plating charging rate is greater than the first non-lithium plating charging rate;

[0158] A third normalization processing module, configured to perform normalization processing on the calibration internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the calibration internal resistance curve, and obtain a normalized calibration curve;

[0159] A rule judgment module, configured to, if the curve trend of the normalized calibration curve is consistent with the curve trend of the normalized standard curve, determine that the preset judgment rule is satisfied.

[0160] In some embodiments, the constant volume capacity of the lithium battery is C 0 ;

[0161] If the charging temperature of the lithium battery is 30°C to 45°C, then the second non-lithium-plating charging rate is 0.5C 0 ~1C 0 ;

[0162] If the charging temperature of the lithium battery is 25°C to 30°C, then the second non-lithium-plating charging rate is 0.5C 0 ~0.8C 0 ;

[0163] If the charging temperature of the lithium battery is 10°C to 25°C, then the second non-lithium-plating charging rate is 0.2C 0 ~0.5C 0 ;

[0164] If the charging temperature of the lithium battery is 0°C to 10°C, then the second non-lithium-plating charging rate is 0.1C 0 ~0.3C 0 ;

[0165] If the charging temperature of the lithium battery is -10°C to 0°C, then the second non-lithium-plating charging rate is 0.1C 0 ~0.2C 0 ;

[0166] If the charging temperature of the lithium battery is -20°C to -10°C, then the second non-lithium-plating charging rate is 0.05C 0 ~0.08C 0 .

[0167] In some embodiments, the preset SOC value is greater than 0% and less than or equal to 20%.

[0168] In one embodiment, the present application further provides a storage medium storing computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to execute the steps of the lithium-plating inflection point detection method in any embodiment.

[0169] In one embodiment, the present application further provides a computer device storing computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to execute the steps of the lithium-plating inflection point detection method in any embodiment.

[0170] Schematically, Figure 11 is an internal structure schematic diagram of a computer device provided by an embodiment of the present application. In one example, the computer device can be a server. Refer toFigure 11 , the computer device 900 includes a processing component 902, which further includes one or more processors, and memory resources represented by a memory 901 for storing instructions executable by the processing component 902, such as application programs. The application programs stored in the memory 901 may include one or more modules each corresponding to a set of instructions. In addition, the processing component 902 is configured to execute instructions to perform the steps of the lithium stripping inflection point detection method described in any of the above embodiments.

[0171] The computer device 900 may further include a power supply component 903 configured to perform power management of the computer device 900, a wired or wireless network interface 904 configured to connect the computer device 900 to a network, and an input / output (I / O) interface 905. The computer device 900 may operate based on an operating system stored in the memory 901, such as Windows Server TM, Mac OS XTM, Unix TM, Linux TM, Free BSDTM, or the like.

[0172] Those skilled in the art can understand that the internal structure of the computer device shown in this application is only a block diagram of a part of the structure related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. A specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0173] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element. In this article, "a", "one", "the", "this" and "its" may also include the plural form unless the context clearly indicates otherwise. A plurality means at least two cases, such as 2, 3, 5 or 8, etc. "And / or" includes any and all combinations of the related listed items.

[0174] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0175] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A lithium precipitation inflection point detection method, characterized in that: include: Obtaining a standard internal resistance curve and an internal resistance curve to be detected of a lithium battery; wherein the standard internal resistance curve is a curve obtained by charging the lithium battery at a first non-lithium deposition charging rate; According to the internal resistance value corresponding to the preset SOC value in the standard internal resistance curve, the standard internal resistance curve is normalized to obtain a normalized standard curve; According to the internal resistance value corresponding to the preset SOC value in the internal resistance curve to be detected, normalizing the internal resistance curve to be detected to obtain a normalized detection curve; If the preset judgment rule is met, the lithium plating inflection point SOC value of the internal resistance curve to be detected is detected based on the deviation of the normalized detection curve from the normalized standard curve.

2. The method according to claim 1, characterized in that The number of the preset SOC values ​​is N, the number of the normalized standard curves and the number of the normalized detection curves are both N, and N is a positive integer greater than 1; The step of detecting the lithium deposition inflection point SOC value of the internal resistance curve to be detected based on the deviation of the normalized detection curve from the normalized standard curve includes: Determine the initial inflection point SOC value of the internal resistance curve to be detected under the target SOC value according to the deviation of the target detection curve from the target standard curve; wherein the target detection curve is a normalized detection curve obtained by normalizing based on the target SOC value, the target standard curve is a normalized standard curve obtained by normalizing based on the target SOC value, and the target SOC value is any one of N preset SOC values; Using a preset inflection point screening rule, M candidate SOC values ​​are screened out from the N initial inflection point SOC values; wherein M≤N; The minimum value among the M candidate SOC values ​​is used as the lithium deposition inflection point SOC value.

3. The method according to claim 2, characterized in that The method of using a preset inflection point screening rule to screen out M candidate SOC values ​​from the N initial inflection point SOC values ​​includes: Compare the curve trends of the first curve segment of the target detection curve with the second curve segment of the target standard curve; wherein the first curve segment is a curve segment in the target detection curve where the SOC value is less than or equal to the target inflection point SOC value, and the second curve segment is a curve segment in the target standard curve where the SOC value is less than or equal to the target inflection point SOC value, and the target inflection point SOC value is the initial inflection point SOC value of the internal resistance curve to be detected corresponding to the target SOC value; If the curve trend of the first curve segment is consistent with the curve trend of the second curve segment, the target inflection point SOC value is used as the candidate SOC value; otherwise, the target inflection point SOC value is excluded.

4. The method according to claim 1, characterized in that: The step of detecting the lithium deposition inflection point SOC value of the internal resistance curve to be detected based on the deviation of the normalized detection curve from the normalized standard curve includes: Respectively calculating a first internal resistance difference and a second internal resistance difference of the normalized detection curve at each SOC value to be detected; wherein the first internal resistance difference is the internal resistance difference between the normalized detection curve and the normalized standard curve at the SOC value to be detected, and the second internal resistance difference is the internal resistance difference corresponding to two adjacent SOC values ​​to be detected; The lithium deposition inflection point SOC value is determined from each of the SOC values ​​to be detected according to each of the first internal resistance differences and each of the second internal resistance differences.

5. The method according to claim 4, characterized in that Determining the lithium deposition inflection point SOC value from each of the SOC values ​​to be detected according to each of the first internal resistance differences and each of the second internal resistance differences includes: If the first internal resistance difference corresponding to the SOC value to be determined is greater than the first preset threshold, and the absolute value of the second internal resistance difference corresponding to the SOC value to be determined is greater than the second preset threshold, the SOC value to be determined is used as the lithium precipitation inflection point SOC value, otherwise, the SOC value to be determined is not used as the lithium precipitation inflection point SOC value; The SOC value to be determined is any one of the SOC values ​​to be detected.

6. The method according to claim 1, characterized in that The judgment step of the preset judgment rule includes: Obtaining a verification internal resistance curve of the lithium battery; wherein the verification internal resistance curve is a curve obtained by charging the lithium battery using a second non-lithium deposition charging rate, and the second non-lithium deposition charging rate is greater than the first non-lithium deposition charging rate; According to the internal resistance value corresponding to the preset SOC value in the verification internal resistance curve, the verification internal resistance curve is normalized to obtain a normalized verification curve; If the curve trend of the normalized verification curve is consistent with the curve trend of the normalized standard curve, it is determined that the preset judgment rule is satisfied.

7. The method according to claim 6, characterized in that The fixed capacity of the lithium battery is C0; If the charging temperature of the lithium battery is 30°C to 45°C, the second non-lithium precipitation charging rate is 0.5C0 to 1C0; If the charging temperature of the lithium battery is 25°C to 30°C, the second non-lithium precipitation charging rate is 0.5C0 to 0.8C0; If the charging temperature of the lithium battery is 10°C to 25°C, the second non-lithium precipitation charging rate is 0.2C0 to 0.5C0; If the charging temperature of the lithium battery is 0°C to 10°C, the second non-lithium precipitation charging rate is 0.1C0 to 0.3C0; If the charging temperature of the lithium battery is -10°C to 0°C, the second non-lithium precipitation charging rate is 0.1C0 to 0.2C0; If the charging temperature of the lithium battery is -20°C to -10°C, the second non-lithium precipitation charging ratio is 0.05C0 to 0.08C0.

8. The method according to any one of claims 1 to 7, characterized in that: The preset SOC value is greater than 0% and less than or equal to 20%.

9. A lithium deposition inflection point detection device, characterized in that: include: A curve acquisition module, used to acquire a standard internal resistance curve and an internal resistance curve to be detected of a lithium battery; wherein the standard internal resistance curve is a curve obtained by charging the lithium battery at a first non-lithium deposition charging rate; A first normalization processing module, configured to perform normalization processing on the standard internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the standard internal resistance curve, and obtain a normalized standard curve; A second normalization processing module, configured to perform normalization processing on the internal resistance curve to be detected according to the internal resistance value corresponding to the preset SOC value in the internal resistance curve to be detected, and obtain a normalized detection curve; The lithium deposition inflection point detection module is used to detect the lithium deposition inflection point SOC value of the internal resistance curve to be detected based on the deviation of the normalized detection curve compared to the normalized standard curve if the preset judgment rule is met.

10. A computer device, characterized in that: include: one or more processors, and memory; The memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the lithium plating inflection point detection method according to any one of claims 1 to 8 are performed.

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