A lithium deposition inflection point detection method, device, storage medium and computer equipment

Abstract

The present application relates to the field of battery technology, and specifically provides a method, device, storage medium and computer equipment for detecting a lithium deposition inflection point. The present application can use the internal resistance values ​​of the standard internal resistance curve and the internal resistance curve to be detected at the same SOC value to normalize the curve, so that 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 without affecting the trend of the curve. Since the normalized standard curve reflects the changing trend of the internal resistance of the lithium battery when no lithium deposition occurs, even if the internal resistance value of the lithium battery shows a downward trend during the entire charging process, the present application can also accurately determine the lithium deposition inflection point of the internal resistance curve to be detected by comparing the internal resistance changing trends of the normalized detection curve and the normalized standard curve, thereby making up for the technical defect that the existing technology cannot detect the lithium deposition inflection point of the aforementioned type of lithium battery, and thus improving the detection accuracy of the lithium deposition inflection point of the lithium battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method, device, storage medium and computer equipment for detecting a lithium plating inflection point. Background Art

[0002] Lithium batteries are widely used in electric vehicles due to their high power density, long lifespan, and environmental friendliness. In recent years, driven by demand for high-performance electric vehicles, lithium batteries have made significant progress in both energy density and lifespan. However, lithium battery safety accidents occur frequently, threatening the lives and property of users. According to statistics on electric vehicle fires, charging-related accidents account for nearly 23% of the total, the largest proportion. This is because lithium plating easily occurs within lithium batteries during overcharging, fast charging, and low-temperature charging. This leads to the growth of lithium dendrites, deteriorating thermal stability, and ultimately increasing the risk of thermal runaway. Therefore, accurate detection of lithium plating is crucial to ensuring safe charging of lithium batteries.

[0003] At present, the existing lithium plating detection methods include: a method based on differential discharge voltage analysis, a method based on voltage relaxation curve, and a method based on impedance. Among them, the first two methods are post-detection methods of the lithium plating process, which can only reflect the lithium plating situation of the lithium battery in the last charging stage, but 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 the lithium battery starts to plaster lithium at SOC=65%, the method based on differential discharge voltage analysis and the method based on voltage relaxation curve can only determine whether the lithium battery plasters lithium at SOC=100%, but cannot detect the node where lithium plating begins, that is, it cannot determine the lithium plating inflection point.

[0004] For example, the impedance-based method provided in CN117192405A uses the principle that the overall impedance of the battery's negative electrode surface decreases when lithium deposition occurs, and determines the lithium deposition inflection point by observing the sudden drop in impedance. However, the impedance of some lithium batteries exhibits a downward trend throughout the charging process, making it difficult to accurately track the changing trend of the impedance curve and, therefore, unable to detect the lithium deposition inflection point in such lithium batteries.

[0005] It can be seen from this that 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 this application is to solve at least one of the above-mentioned technical defects, especially the technical defect that the prior art cannot accurately detect the lithium deposition inflection point of lithium batteries.

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

[0008] Obtaining a standard internal resistance curve and an internal resistance curve to be tested of a lithium battery; wherein the standard internal resistance curve is a curve obtained by charging the lithium battery using a first non-lithium deposition charging rate;

[0009] Normalizing the standard internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the standard internal resistance curve to obtain a normalized standard curve;

[0010] Normalizing 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 obtaining a normalized detection curve;

[0011] If the preset judgment rule is met, the lithium deposition inflection point SOC value of the internal resistance curve to be detected is detected based on the deviation of the normalized detection curve compared to the normalized standard curve.

[0012] 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;

[0013] The 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:

[0014] Determining an initial inflection point SOC value of the internal resistance curve to be tested at a target SOC value based on a deviation of the target detection curve from the target standard curve; wherein the target detection curve is a normalized detection curve obtained by normalizing the target SOC value, the target standard curve is a normalized standard curve obtained by normalizing the target SOC value, and the target SOC value is any one of N preset SOC values;

[0015] 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;

[0016] The minimum value among the M candidate SOC values ​​is used as the lithium deposition inflection point SOC value.

[0017] In some embodiments, 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:

[0018] Comparing the curve trends of a first curve segment of the target detection curve and a second curve segment of the target standard curve; wherein the first curve segment is a curve segment in the target detection curve whose SOC value is less than or equal to a target inflection point SOC value, and the second curve segment is a curve segment in the target standard curve whose 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;

[0019] 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.

[0020] In some embodiments, 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:

[0021] Calculating a first internal resistance difference and a second internal resistance difference of the normalized detection curve at each SOC value to be detected, respectively; 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] 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.

[0023] In some embodiments, determining the lithium deposition inflection point SOC value from each of the SOC values ​​to be detected based on 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 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 deposition inflection point SOC value; otherwise, the SOC value to be determined is not used as the lithium deposition inflection point SOC value;

[0025] The SOC value to be determined is any one of the SOC values ​​to be detected.

[0026] In some embodiments, the determination step of the preset determination rule includes:

[0027] Obtaining a calibration internal resistance curve of the lithium battery; wherein the calibration 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;

[0028] Normalizing the verification internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the verification internal resistance curve to obtain a normalized verification curve;

[0029] 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 met.

[0030] In some embodiments, the lithium battery has a fixed capacity of C0;

[0031] 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;

[0032] 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;

[0033] 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;

[0034] 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;

[0035] 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;

[0036] If the charging temperature of the lithium battery is -20°C to -10°C, the second non-lithium precipitation charging rate is 0.05C0 to 0.08C0.

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

[0038] In a second aspect, an embodiment of the present application provides a lithium deposition inflection point detection device, comprising:

[0039] A curve acquisition module is used to obtain a standard internal resistance curve and an internal resistance curve to be tested of the lithium battery; wherein the standard internal resistance curve is a curve obtained by charging the lithium battery using a first non-lithium deposition charging rate;

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

[0041] 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;

[0042] 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.

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

[0044] 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 described in any of the above embodiments are performed.

[0045] In the lithium plating inflection point detection method, device, storage medium and computer equipment provided in some embodiments of the present application, the standard internal resistance curve can be normalized according to the internal resistance value of the standard internal resistance curve at a preset SOC value, and a normalized standard curve can be obtained. In addition, the internal resistance curve to be detected can be normalized according to the internal resistance value of the internal resistance curve to be detected 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, it is possible to reasonably map the various internal resistance values ​​of the internal resistance curve to be detected and the various internal resistance values ​​of the standard internal resistance curve to the same value range without affecting the trend of the curve.

[0046] Since the standard internal resistance curve is the internal resistance curve corresponding to the non-lithium deposition charging rate, the normalized standard curve can reflect the changing trend of the internal resistance of the lithium battery when no lithium deposition occurs. By comparing the internal resistance changing trends of the normalized detection curve and the normalized standard curve, the lithium deposition inflection point SOC value of the internal resistance curve to be detected 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 deposition inflection point SOC value through curve trend comparison, thereby making up for the technical defect that the prior art cannot detect the lithium deposition inflection point of the aforementioned type of lithium battery, and thus improving the detection accuracy of the lithium deposition inflection point of the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0048] Figure 1 Schematic diagram of a process for detecting the lithium deposition inflection point in some embodiments;

[0049] Figure 2 1. The internal resistance curve of the lithium battery at different charge rates in some embodiments;

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

[0051] Figure 4 In some embodiments, the current variation of the lithium battery during a single charging and resting cycle;

[0052] Figure 5 To use 5% as the preset SOC value, Figure 2 The result of normalization processing;

[0053] Figure 6 To use 10% as the preset SOC value, Figure 2 The result of normalization processing;

[0054] Figure 7 To use 15% as the preset SOC value, Figure 2 The result of normalization processing;

[0055] Figure 8 To use 50% as the preset SOC value, Figure 2 The result of normalization processing;

[0056] Figure 9 1 is a flow chart of the step of detecting the SOC value of the lithium deposition inflection point of the internal resistance curve to be detected in some embodiments;

[0057] Figure 10 Schematic diagram of the structure of a lithium deposition inflection point detection device in some embodiments;

[0058] Figure 11 This is a diagram of the internal structure of a computer device in some embodiments. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0060] In some embodiments, the present application provides a method for detecting a lithium plating inflection point. The following embodiments illustrate this method using a computer device as an example. It is understood that the computer device described herein can be any device with data acquisition and data processing capabilities, including, but not limited to, a tablet computer, a notebook computer, a laptop computer, a desktop computer, a smartphone, a wearable device, an IoT device, or a server cluster consisting of one or more servers.

[0061] like Figure 1 As shown, the lithium deposition inflection point detection method provided in this application may include the following steps:

[0062] S102: Obtaining a standard internal resistance curve and an internal resistance curve to be tested of the lithium battery.

[0063] The first no-lithium deposition charge rate refers to a charge rate that will not or almost will not cause lithium deposition in the lithium battery, and can be determined based on actual conditions such as battery temperature and battery type. The standard internal resistance curve is an internal resistance curve obtained by charging a lithium battery at the first no-lithium deposition charge rate. The standard internal resistance curve reflects how the internal resistance of a lithium battery changes with the state of charge during charging at the first no-lithium deposition charge rate.

[0064] The internal resistance curve to be tested is an internal resistance curve obtained by charging the lithium battery with the target charging rate, which can reflect the situation in which the internal resistance value of the lithium battery changes with the state of charge in the process of charging the lithium battery with the target charging rate. The target charging rate is greater than the first non-lithium precipitation charging rate, and the target charging rate can be a charging rate required to determine the lithium precipitation inflection point. The specific value can be determined according to the actual situation. The target charging rate can be formulated according to the fast charging demand. This application does not impose specific restrictions 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 of 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 tested are the same indicator dimension, and the ordinate of the standard internal resistance curve and the ordinate of the internal resistance curve to be tested are the same indicator dimension. In some examples, the abscissa of the standard internal resistance curve and the internal resistance curve to be tested can both be internal resistance values, and the ordinate can both be SOC values. In other examples, the abscissa of the standard internal resistance curve and the internal resistance curve to be tested can both be SOC values, and the ordinate can both be internal resistance values. For ease of explanation, the embodiments of the present application are described as examples with the abscissa being the SOC value and the ordinate being the internal resistance value.

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

[0067] It should be noted that the standard internal resistance curve and the internal resistance curve to be tested can be measured using any measurement method using a battery internal resistance measurement device, and this application does not impose specific restrictions on this. The computer device described in this application can be a component of the battery internal resistance measurement device, or it can be a device independent of the battery internal resistance measurement device, and this application does not impose specific restrictions on this.

[0068] In some examples, taking the measurement of the standard internal resistance curve as an example, the battery internal resistance measuring device can charge the lithium battery at a first non-lithium precipitation charging rate, and stand for m seconds after each charging of n% SOC, and charge the SOC of the lithium battery to 100% through multiple charging and standing cycles. Wherein, n and m are both preset positive integers. For example, if n=5 and m=10, when the SOC of the lithium battery is charged to 5%, stand for 10 seconds, and after standing for 10 seconds, charge the SOC of the lithium battery to 10%, and then stand for 10 seconds. After the second standing, charge the SOC of the lithium battery to 15%, and then stand 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 R of the lithium battery at the corresponding SOC value based on the voltage change value △V and current change value △I before and after the same static state, using R=△V / △I. Figure 3 and Figure 4 The voltage change value △V can be the difference between the last charging voltage and the last resting voltage of the lithium battery in the current charging rest cycle. The current change value △I can be the difference between the last charging current and the last resting current of the lithium battery in the current charging rest cycle. Ideally, the current is strictly zero during rest, but in reality, measurement errors or charging current drops can occur during rest. Therefore, current interpolation can more accurately reflect the actual current change. Furthermore, ohmic polarization disappears instantaneously (in the μs range) after the current returns to zero, significantly alleviating concentration polarization. This lowers the charging current, further reducing the impact of polarization and improving measurement accuracy.

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

[0071] S104: performing 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 obtaining a normalized standard curve.

[0072] Specifically, from Figure 2 It can be seen that at different charging rates, the value range of the internal resistance of the lithium battery is different. It is difficult to directly compare the standard internal resistance curve with the internal resistance curve to be tested, and it is impossible to obtain accurate results. Therefore, this application normalizes the internal resistance curve and obtains a normalized curve.

[0073] In this step, each internal resistance value of the standard internal resistance curve can be normalized based on the internal resistance value of the standard internal resistance curve at the preset SOC value, thereby obtaining a normalized standard curve. It should be noted that the number of preset SOC values ​​can be one or more, and the number can be determined based on actual conditions, and this application does not impose specific restrictions on this.

[0074] When the preset SOC value is one, the present application can use the internal resistance value of the standard internal resistance curve at the preset SOC value as the normalized standard value, and normalize the standard internal resistance curve according to the internal resistance value / normalized standard value method to obtain a 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 normalized 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 normalized 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 use the internal resistance value of the standard internal resistance curve at each preset SOC value as a normalized standard value, and perform normalization processing accordingly, so as to obtain a normalized standard curve 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 normalized standard value, perform normalization calculation on each internal resistance value of the standard internal resistance curve, and obtain a first normalized standard curve corresponding to SOC=10%. In addition, the present application can also use the internal resistance value of the standard internal resistance curve at SOC=30% as the normalized standard value, perform normalization calculation on each internal resistance value of the standard internal resistance curve, and obtain a second normalized standard curve corresponding to SOC=30%. The specific normalization calculation process can be found in the description above, and the present application will not repeat it here.

[0076] S106: performing 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 obtaining a normalized detection curve.

[0077] In this step, the internal resistance values ​​of the internal resistance curve to be tested can be normalized based on the internal resistance value of the internal resistance curve to be tested at the preset SOC value, thereby obtaining a normalized detection curve. For relevant instructions on the preset SOC value and normalization calculation, please refer to the description of the normalized standard curve above, and this application will not repeat them here.

[0078] For example, Figure 5 The default SOC value is 5%. Figure 2 The internal resistance curves shown are normalized results. Figure 6 The default SOC value is 10%. Figure 2 The internal resistance curves shown are normalized results. Figure 7 The default SOC value is 15%. Figure 2 The internal resistance curves shown are normalized results. Figure 8 The default SOC value is 50%. Figure 2 The internal resistance curves shown are normalized results.

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

[0080] The preset judgment rule refers to the rule used to determine whether to determine the lithium deposition inflection point based on the normalized detection curve and the normalized standard curve. The specific content of the rule can be determined based on actual conditions. The lithium deposition inflection point SOC value refers to the SOC value corresponding to the start of lithium deposition in the lithium battery. The deviation of the normalized detection curve from the normalized standard curve refers to the deviation of the normalized detection curve from the benchmark with the normalized standard curve as the benchmark.

[0081] The internal resistance change trend of the lithium battery after lithium deposition is different from the internal resistance change trend of the lithium battery without lithium deposition. Therefore, the present application can compare the internal resistance change trend of the lithium battery at the first non-lithium deposition 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 deriving the lithium deposition inflection point SOC value of the lithium battery at the target charging rate.

[0082] The present application can use the internal resistance value of the internal resistance curve itself for normalization, so that 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 without affecting the trend of the curve. Due to different charge and discharge rates, the electrochemical reaction rate and polarization degree inside the battery will be affected. Through the above-mentioned normalization process, the internal resistance curves under different charge rates can be unified into the same numerical range, so as to more intuitively compare the internal resistance change trend under different rates. For example, under low temperature conditions, the battery internal resistance curves under different charge rates may be difficult to directly compare due to differences in numerical ranges. Through this application, the lithium precipitation inflection point can be more clearly reflected. At the same time, in actual tests, the data will fluctuate or 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 lithium precipitation inflection point detection. By comparing the internal resistance change trends of the normalized detection curve and the normalized standard curve, the present application can determine the SOC value of the lithium deposition inflection point of the internal resistance curve to be tested based on the deviation of the normalized detection curve compared to 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 SOC value of the lithium deposition inflection point by comparing the curve trends, thereby compensating for the technical defect of the existing technology that cannot detect the lithium deposition inflection point of the aforementioned type of lithium battery, and further improving the detection accuracy of the lithium deposition inflection point of the lithium battery.

[0083] At the same time, the present application has the advantage of being easy to use and can be easily coupled with the battery charge and discharge program. In this way, it is convenient to adjust the battery charge and discharge program when the lithium deposition node is determined to occur, preventing lithium deposition from occurring on the battery negative electrode surface, thereby improving the overall safety performance of the battery, and preventing the loss of active materials and interface degradation, thereby increasing the battery life.

[0084] In some embodiments, the number of preset SOC values ​​is N, where 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] like Figure 9 As shown, based on the deviation of the normalized detection curve from the normalized standard curve, the lithium plating inflection point SOC value of the internal resistance curve to be tested is detected, including:

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

[0087] 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.

[0088] Specifically, when there are multiple preset SOC values, the present application 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 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 compared with the target standard curve, and then determining the lithium plating inflection point of the internal resistance curve to be detected at the preset SOC value, and obtaining the initial inflection point SOC value corresponding to the preset SOC value.

[0089] For example, in the above example where N=2, the computer device may compare the first normalized standard curve with the first normalized detection curve, and determine the lithium deposition 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, and obtain the initial inflection point SOC value corresponding to the first SOC value. Similarly, the computer device may compare the second normalized standard curve with the second normalized detection curve, and determine the lithium deposition 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, and obtain the initial inflection point SOC value corresponding to the second SOC value.

[0090] For example, in Figures 5 to 8In 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, select M candidate SOC values ​​from the N initial inflection point SOC values; wherein M≤N.

[0092] The inflection point screening rule content can be pre-set based on actual conditions. The computer device can screen the N initial inflection point SOC values ​​according to the preset inflection point screening rule to exclude 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: The minimum value among the M candidate SOC values ​​is used as the lithium deposition inflection point SOC value.

[0094] That is, in the normalized detection curve under different preset SOCs at the same target charge rate, the minimum SOC value of each inflection point is selected as the final lithium deposition inflection point. Figures 5 to 8 In the example shown, if the internal resistance curve to be tested is the internal resistance curve corresponding to 1C, then the four initial inflection point SOC values ​​are 45%, 45%, 45%, and 55%, respectively. If the aforementioned four initial inflection point SOC values ​​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 1C charge rate.

[0095] In this embodiment, curve normalization is performed based on multiple preset SOC values, and multiple initial inflection point SOC values ​​are screened. The minimum value of the M candidate SOC values ​​obtained by screening is used as the lithium deposition inflection point at the target charge rate. The lithium deposition inflection point at different target charge rates can be output to facilitate determining the charging strategy based on different charge rates. By adjusting the charge and discharge degree of the lithium battery based on the lithium deposition inflection point determined in this embodiment, the probability of lithium deposition in the lithium battery can be effectively reduced, thereby improving the safety of the lithium battery.

[0096] In some embodiments, a preset inflection point screening rule is used to screen out M candidate SOC values ​​from N initial inflection point SOC values, including:

[0097] Step A2: Comparing the curve trends of the first curve segment of the target detection curve and 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;

[0098] Step A4: 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 a candidate SOC value; otherwise, the target inflection point SOC value is excluded.

[0099] Specifically, when lithium plating does not occur in the lithium battery, the curve trend of the normalized detection curve should be consistent with the curve trend of the normalized standard curve. However, if the preset SOC value is improperly selected, even if lithium plating does not occur in the lithium battery, the curve trend of the normalized detection curve may differ from the curve trend of the normalized standard curve. This will affect the detection accuracy of the SOC value of the lithium plating inflection point, so it is necessary to exclude this curve to further improve the detection accuracy of the lithium plating inflection point.

[0100] In this embodiment, the computer device may 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 the preset SOC value based on the deviation of the target detection curve from the target standard curve. The initial inflection point SOC value is the target inflection point SOC value.

[0101] The computer device may use the curve segment in the target detection curve where the SOC value is less than the target inflection point SOC value as the first curve segment, which reflects the internal resistance change trend of the lithium battery when lithium plating does not occur. The computer device may use the curve segment in 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 trend of the first curve segment is inconsistent with the trend of the second curve segment, it indicates that the preset SOC value is improperly selected and the trend of the target detection curve cannot reflect the actual change in the internal resistance of the lithium battery. To prevent the target detection curve from interfering with the lithium plating judgment, the computer device can exclude the initial inflection point SOC value corresponding to the target detection curve.

[0103] On the contrary, 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 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 deposition inflection point SOC value of the internal resistance curve to be detected includes:

[0105] Step B2: Calculating 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 of the normalized detection curve;

[0106] Step B4: determining the lithium deposition inflection point SOC value from each SOC value to be detected according to each first internal resistance difference and each second internal resistance difference.

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

[0108] Specifically, the SOC value to be detected refers to the SOC value for which the internal resistance difference needs to be calculated. The number and specific SOC value can be determined based on actual conditions, and this application does not impose any 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 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. Wherein, i refers to the order of arrangement corresponding to the SOC values ​​to be detected after sorting the SOC values ​​to be detected in order from small to large.

[0110] For example, in Figures 5 to 8In the example, the SOC values ​​to be tested can be 5%, 10%, 15%, 20%, 25%, ... 100%. Among them, 5% is the first SOC value to be tested, 10% is the second SOC value to be tested, 15% is the third SOC value to be tested, and so on. When calculating the internal resistance difference corresponding to SOC=5%, we can first determine the internal resistance value R of the normalized detection curve at SOC=5%. 检测|SOC=5% , the internal resistance value R of the normalized detection curve at SOC=10% 检测|SOC=10% And the internal resistance value R of the normalized standard curve at SOC=5% 标准|SOC=5% , and R 检测|SOC=5% With R 标准|SOC=5% The difference between the two values ​​is taken as the first internal resistance difference corresponding to SOC=5%, and R 检测|SOC=5% With R 检测|SOC=10% The difference is taken as the second internal resistance difference corresponding to SOC=5%.

[0111] When 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 deposition 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 deposition inflection point SOC value from 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 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 deposition inflection point SOC value; otherwise, the SOC value to be determined is not used as the lithium deposition inflection point SOC value;

[0114] The SOC value to be determined is any one of the SOC values ​​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 value, and compare the absolute value of the second internal resistance difference corresponding to the SOC value to be detected with the second preset threshold value, and determine whether the SOC value to be detected on the normalized detection curve is the SOC value of the lithium deposition inflection point based on the size comparison results. In this way, the detection efficiency of the lithium deposition inflection point can be improved while ensuring the accuracy of the lithium deposition inflection point detection.

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

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

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

[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 deposition inflection point SOC value;

[0120] (4) If the first internal resistance difference is greater than the first preset threshold value, and the absolute value of the second internal resistance difference is less than or equal to the second preset threshold value, 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 based on 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 therebetween is selected as the first preset threshold. For example, if the maximum value of the internal resistance difference 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 applicability of the evaluation. Furthermore, the internal resistance difference between adjacent SOC values ​​in the normalized standard curve with the smallest charging rate can be calculated, and the maximum value therebetween 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 difference between adjacent SOC values ​​is 0.073, and 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 applicability of the evaluation.

[0122] In some embodiments, the determination step of the preset determination rule includes:

[0123] Step C2: Obtaining a calibration internal resistance curve of the lithium battery; wherein the calibration 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;

[0124] Step C4: normalizing the verification internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the verification internal resistance curve to obtain a normalized verification curve;

[0125] Step C6: 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.

[0126] The second no-lithium deposition charge rate refers to a charge rate that will not or almost will not cause lithium deposition in the lithium battery. It can be determined based on actual conditions such as battery temperature and battery type, and this application does not impose specific restrictions on this. The internal resistance curve obtained by charging the lithium battery without using the second no-lithium deposition charge rate can reflect how the internal resistance of the lithium battery changes with the state of charge during the process of charging the lithium battery using the second no-lithium deposition charge rate.

[0127] In most cases, the higher the charge rate, the higher the probability of lithium deposition. If lithium deposition does not occur in a lithium battery at a higher charge rate, then lithium deposition will also not occur in the lithium battery at a lower charge rate. Therefore, this embodiment can use this principle to verify whether the standard internal resistance curve is the internal resistance curve of a lithium battery without lithium deposition, thereby further improving the accuracy of detecting the lithium deposition inflection point.

[0128] In this embodiment, when a lithium battery calibration internal resistance curve is obtained, each internal resistance value of the calibration internal resistance curve can be normalized based on the internal resistance value of the calibration internal resistance curve at a preset SOC value, thereby obtaining a normalized calibration curve. For details about the preset SOC value and normalization calculation, please refer to the description of the normalized standard curve above, and this application will not repeat them here.

[0129] After obtaining the normalized verification curve, the present application can compare the internal resistance change trend of the normalized verification curve with the internal resistance change curve of the normalized standard curve to determine whether the two have consistent curve trends, and then verify whether the lithium battery does not deposit lithium during the entire charging cycle during the charging process using the first non-lithium deposition charging rate.

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

[0131] Furthermore, in some examples, if the curve trend of the normalized verification curve is inconsistent with the curve trend of the normalized standard curve, the present application can re-acquire a standard internal resistance curve and a calibration internal resistance curve. The re-acquired standard internal resistance curve (hereinafter referred to as the second standard internal resistance curve) can be an internal resistance curve obtained by charging the lithium battery using a third non-lithium deposition charging rate, and the re-acquired verification internal resistance curve (hereinafter referred to as the second verification internal resistance curve) can be an internal resistance curve obtained by charging the lithium battery using a fourth non-lithium deposition charging rate. The third non-lithium deposition charging rate and the fourth non-lithium deposition charging rate are both lower than the first non-lithium deposition charging rate, and the fourth non-lithium deposition charging rate is higher than the third non-lithium deposition charging rate.

[0132] The present application can normalize the second standard internal resistance curve according to the above steps to obtain a third normalized standard curve. Furthermore, the second verification internal resistance curve can be normalized according to the above steps to obtain a second normalized verification curve. If the curve trend of the second normalized verification curve is consistent with the curve trend of the third normalized standard curve, the third normalized standard curve is used as a reference to determine the lithium deposition inflection point.

[0133] In some embodiments, the fixed capacity of the lithium battery is C0. It will be understood that the capacitance of the lithium battery can be determined in any way, and this application does not impose any specific restrictions on this. In some examples, the lithium battery can be fixed in capacity by using 0.33C constant current and constant voltage charging and 0.33C discharge at room temperature for 3 weeks. In this process, the voltage range is 2.5V~3.65V, and the discharge capacity of the third week is taken as the fixed capacity C0. For example, when a 100Ah battery cell is fixed in capacity according to the above method, its fixed capacity can be 100.28Ah.

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

[0135] Specifically, if the charging temperature of the lithium battery is 30℃~45℃, the second non-lithium precipitation charging rate is 0.5C0~1C0; if the charging temperature of the lithium battery is 25℃~30℃, the second non-lithium precipitation charging rate is 0.5C0~0.8C0; if the charging temperature of the lithium battery is 10℃~25℃, the second non-lithium precipitation charging rate is 0.2C0~0.5C0; if the charging temperature of the lithium battery is 0℃~10℃, the second non-lithium precipitation charging rate is 0.1C0~0.3C0; if the charging temperature of the lithium battery is -10℃~0℃, the second non-lithium precipitation charging rate is 0.1C0~0.2C0; if the charging temperature of the lithium battery is -20℃~-10℃, the second non-lithium precipitation charging rate is 0.05C0~0.08C0.

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

[0137] The lithium deposition inflection point detection device provided in an embodiment of the present application is described below. The lithium deposition inflection point detection device described below and the lithium deposition inflection point detection method described above can be referenced to each other.

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

[0139] The curve acquisition module 302 is used to obtain a standard internal resistance curve and an internal resistance curve to be tested of the lithium battery; wherein the standard internal resistance curve is a curve obtained by charging the lithium battery using a first non-lithium deposition charging rate;

[0140] A 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] A second normalization processing module 306 is 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;

[0142] The lithium deposition inflection point detection module 308 is configured 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 from the normalized standard curve if a preset judgment rule is met.

[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 deposition inflection point detection module 308 of the present application includes:

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

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

[0146] The first lithium deposition inflection point determining unit is configured to use the minimum value among the M candidate SOC values ​​as the lithium deposition inflection point SOC value.

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

[0148] a curve trend comparison unit, configured to perform a curve trend comparison between a first curve segment of the target detection curve and a second curve segment of the target standard curve; wherein the first curve segment is a curve segment in the target detection curve whose SOC value is less than or equal to a target inflection point SOC value, and the second curve segment is a curve segment in the target standard curve whose SOC value is less than or equal to the target inflection point SOC value, and the target inflection point SOC value is an initial inflection point SOC value of the internal resistance curve to be detected corresponding to the target SOC value;

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

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

[0151] an internal resistance difference calculation unit, configured to respectively 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] The second lithium deposition inflection point determining unit is configured to determine 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.

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

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

[0155] The SOC value to be determined is any one of the SOC values ​​to be detected.

[0156] In some embodiments, the lithium deposition 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 deposition charging rate, the second non-lithium deposition charging rate being greater than the first non-lithium deposition charging rate;

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

[0159] The rule judgment module is used to determine that the preset judgment rule is satisfied if the curve trend of the normalized verification curve is consistent with the curve trend of the normalized standard curve.

[0160] In some embodiments, the lithium battery has a fixed capacity of C0;

[0161] 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;

[0162] 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;

[0163] 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;

[0164] 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;

[0165] 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;

[0166] If the charging temperature of the lithium battery is -20°C to -10°C, the second non-lithium precipitation charging rate is 0.05C0 to 0.08C0.

[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 also provides a storage medium storing computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the lithium plating inflection point detection method in any embodiment.

[0169] In one embodiment, the present application also provides a computer device having computer-readable instructions stored therein. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the lithium plating inflection point detection method in any embodiment.

[0170] Schematically, Figure 11 This is a schematic diagram of the internal structure of a computer device provided in an embodiment of the present application. In one example, the computer device may be a server. Figure 11 Computer device 900 includes a processing component 902, which further includes one or more processors, and memory resources represented by memory 901 for storing instructions executable by processing component 902, such as application programs. The application programs stored in memory 901 may include one or more modules, each corresponding to a set of instructions. In addition, processing component 902 is configured to execute the instructions to perform the steps of the lithium deposition 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™, Mac OS X™, Unix™, Linux™, Free BSD™, or the like.

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

[0173] Finally, it should be noted that, in this article, relational terms such as first and second are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprise," "include," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. Without further restriction, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element. Herein, "one," "said," "the," and "its" may also include plural forms unless the context clearly indicates otherwise. A plurality refers to at least two, such as 2, 3, 5, or 8. "And / or" includes any and all combinations of the relevant listed items.

[0174] The various embodiments in this specification are described in a progressive manner, and 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 referenced to each other.

[0175] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform 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 tested of a lithium battery; wherein the standard internal resistance curve is a curve obtained by charging the lithium battery using a first non-lithium deposition charging rate; Normalizing the standard internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the standard internal resistance curve to obtain a normalized standard curve; Normalizing 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 obtaining a normalized detection curve; If the preset judgment rule is met, the lithium deposition inflection point SOC value of the internal resistance curve to be tested is detected based on the deviation of the normalized detection curve from the normalized standard curve; The judgment steps of the preset judgment rules include: Obtaining a calibration internal resistance curve of the lithium battery; wherein the calibration 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; Normalizing the verification internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the verification internal resistance curve 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; The 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: Calculating a first internal resistance difference and a second internal resistance difference of the normalized detection curve at each SOC value to be detected, respectively; 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.

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 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: Determining an initial inflection point SOC value of the internal resistance curve to be tested at a target SOC value based on a deviation of the target detection curve from the target standard curve; wherein the target detection curve is a normalized detection curve obtained by normalizing the target SOC value, the target standard curve is a normalized standard curve obtained by normalizing 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: Comparing the curve trends of a first curve segment of the target detection curve and a second curve segment of the target standard curve; wherein the first curve segment is a curve segment in the target detection curve whose SOC value is less than or equal to a target inflection point SOC value, and the second curve segment is a curve segment in the target standard curve whose 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, wherein 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 deposition inflection point SOC value; otherwise, the SOC value to be determined is not used as the lithium deposition inflection point SOC value; The SOC value to be determined is any one of the SOC values ​​to be detected.

5. The method according to claim 1, wherein 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 rate is 0.05C0 to 0.08C0.

6. The method according to any one of claims 1 to 5, characterized in that The preset SOC value is greater than 0% and less than or equal to 20%.

7. A lithium deposition inflection point detection device, characterized in that: include: A curve acquisition module is used to obtain a standard internal resistance curve and an internal resistance curve to be tested of the lithium battery; wherein the standard internal resistance curve is a curve obtained by charging the lithium battery using 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 an internal resistance value corresponding to a 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; 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 deposition charging rate, the second non-lithium deposition charging rate being greater than the first non-lithium deposition charging rate; a third normalization processing module, configured to perform normalization processing on the verification internal resistance curve according to the internal resistance value corresponding to the preset SOC value in the verification internal resistance curve, and obtain a normalized verification curve; a rule judgment module, configured to determine that a preset judgment rule is satisfied if a curve trend of the normalized verification curve is consistent with a curve trend of the normalized standard curve; a lithium deposition inflection point detection module, configured to detect a lithium deposition inflection point SOC value of the internal resistance curve to be detected based on a deviation of the normalized detection curve from the normalized standard curve if a preset judgment rule is met; Wherein, the lithium deposition inflection point detection module includes: an internal resistance difference calculation unit, configured to respectively 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; The second lithium deposition inflection point determining unit is configured to determine 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.

8. 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 6 are performed.

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