A method, device and electronic device for determining the lithium plating potential of a lithium-ion battery

Abstract

The present invention discloses a method, device and electronic device for determining the lithium plating potential of a lithium-ion battery. The method for determining the lithium plating potential of a lithium-ion battery includes: performing a charging test on the lithium-ion battery and collecting voltage and capacity data of the lithium-ion battery during the charging test; wherein, during the same charging test, the charging rate is the same and the charging temperature is the same; performing differential processing on the voltage and capacity data to obtain the first-order differential dQ / dV-V curve of the charging capacity and the second-order differential d²Q / dV²-V curve of the charging capacity of the lithium-ion battery; determining the lithium plating state of the lithium-ion battery and determining the lithium plating potential of the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity and the second-order differential d²Q / dV²-V curve of the charging capacity of the lithium-ion battery, solving the problems of long time consumption and low accuracy in lithium plating detection of the lithium-ion battery, and being able to clearly and intuitively see the true lithium plating potential of the lithium-ion battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular, to a method, device, and electronic device for determining the lithium plating potential of a lithium-ion battery. Background Art

[0002] In recent years, due to advantages such as light weight, high energy density, and long service life, lithium-ion batteries have been widely used in electric vehicles. While continuously pursuing longer battery life, people have put forward higher requirements for fast charging performance. However, lithium-ion batteries still have various aging mechanisms, such as lithium plating, growth of the solid electrolyte interface (SEI) film, and loss of positive electrode active materials, which accelerate the attenuation of battery capacity and may also cause safety problems.

[0003] Currently, commonly used methods for detecting lithium plating in lithium-ion batteries include: three-electrode method, voltage relaxation method, discharge voltage plateau method, DC internal resistance method, Coulomb efficiency method, etc. However, all of these methods have the disadvantages of inconvenient operation, special test conditions, long test cycles, and none of them can obtain the actual lithium plating potential during the charging process of lithium-ion batteries. Summary of the Invention

[0004] The present invention provides a method, device, and electronic device for determining the lithium plating potential of a lithium-ion battery, which solves the problems of long detection time and low accuracy of lithium plating detection in lithium-ion batteries, and can clearly and intuitively show the true lithium plating potential of lithium-ion batteries.

[0005] According to one aspect of the present invention, a method for determining the lithium plating potential of a lithium-ion battery is provided. The method for determining the lithium plating potential of a lithium-ion battery includes:

[0006] Performing a charging test on the lithium-ion battery and collecting voltage and capacity data of the lithium-ion battery during the charging test; wherein, during the same charging test, the charging rate is the same and the charging temperature is the same;

[0007] Performing a differential processing on the voltage and capacity data to obtain a first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and a second-order differential d 2 Q / dV 2 -V curve of the charging capacity;

[0008] Judging the lithium plating state of the lithium-ion battery and determining the lithium plating potential of the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve.

[0009] Further, when the charging rate of the lithium-ion battery is less than the preset charging rate and the charging temperature is greater than the preset temperature, the lithium plating state of the lithium-ion battery is judged according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve, and the lithium plating potential of the lithium-ion battery is determined. The method for determining the lithium plating potential of the lithium-ion battery includes:

[0010] Judge whether the lithium-ion battery has lithium plating according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery;

[0011] If the lithium-ion battery has lithium plating, then according to the second-order differential d of the charging capacity of the lithium-ion battery 2 Q / dV 2 -V curve to determine the lithium plating potential of the lithium-ion battery.

[0012] Further, when the charging rate of the lithium-ion battery is greater than the preset charging rate and / or the charging temperature is less than the preset temperature, the lithium plating state of the lithium-ion battery is judged according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve, and after confirming that the lithium-ion battery has lithium plating, the lithium plating potential of the lithium-ion battery is determined. The method for determining the lithium plating potential of the lithium-ion battery includes:

[0013] According to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery, and combined with the second-order differential d of the charging capacity of the lithium-ion battery 2 Q / dV 2 -V curve to judge whether the lithium-ion battery has lithium plating;

[0014] If the lithium-ion battery has lithium plating, then according to the second-order differential d of the charging capacity of the lithium-ion battery 2 Q / dV 2 -V curve to determine the lithium plating potential of the lithium-ion battery.

[0015] Further, judge whether the lithium-ion battery has lithium plating according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery. The method for determining the lithium plating potential of the lithium-ion battery includes:

[0016] Judge whether there is a lithium plating characteristic peak in the phase transition peak of the first-order differential dQ / dV-V curve of the charging capacity;

[0017] If it exists, it is determined that the lithium-ion battery has lithium plating; among them, when the lithium-ion battery has a lithium plating reaction, a voltage platform representing lithium plating will be newly added, and the voltage platform representing lithium plating corresponds to the lithium plating characteristic peak.

[0018] Further, based on the second derivative d 2 Q / dV 2 -V curve of the charging capacity of the lithium-ion battery, the method for determining the lithium plating potential of the lithium-ion battery includes:

[0019] Determine the second derivative d 2 Q / dV 2 - The voltage corresponding to the maximum value point of the lithium plating characteristic peak in the V curve;

[0020] Take the second derivative d of the charging capacity 2 Q / dV 2 - The voltage corresponding to the maximum value point of the lithium plating characteristic peak in the V curve is determined as the lithium plating potential of the lithium-ion battery.

[0021] Further, conduct a charging test on the lithium ions. The method for determining the lithium plating potential of the lithium-ion battery includes:

[0022] According to the combined relationship between the charging temperature and the charging rate in the preset charging test chart, conduct charging tests on the lithium-ion battery at different charging rates at multiple charging temperatures; among them, the charging rates at each charging temperature at least include the charging rate without lithium plating and the maximum allowable continuous charging rate; during each charging test, fully charge the lithium-ion battery to the cut-off voltage according to the charging rate.

[0023] Further, the method for determining the lithium plating potential of the lithium-ion battery further includes:

[0024] At the same charging rate, obtain the second derivative d of the charging capacity corresponding to different charging temperatures of the lithium-ion battery 2 Q / dV 2 -V curve to determine the lithium plating potential of the lithium-ion battery at different charging temperatures;

[0025] And / or, at the same charging temperature, obtain the second derivative d of the charging capacity corresponding to different charging rates of the lithium-ion battery 2 Q / dV 2 -V curve to determine the lithium plating potential of the lithium-ion battery at different charging rates.

[0026] Further, the charging temperature range in which the lithium-ion battery allows continuous charging includes -30°C to 55°C; the charging rate range in which the lithium-ion battery allows continuous charging includes 0.01C to 2C;

[0027] During the charging test of the lithium-ion battery, the charging voltage acquisition time interval is less than or equal to 1S, and the charging voltage acquisition accuracy is less than or equal to 1mV.

[0028] According to another aspect of the present invention, there is provided a device for determining the lithium plating potential of a lithium-ion battery, the device for determining the lithium plating potential of a lithium-ion battery comprising:

[0029] A data acquisition module, configured to acquire voltage and capacity data of the lithium-ion battery during a charging test of the lithium-ion battery; wherein, during the same charging test, the charging rate is the same and the charging temperature is the same;

[0030] A differential processing module, which performs differential processing on the voltage and the capacity data to obtain a first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and a second-order differential d 2 Q / dV 2 -V curve;

[0031] A lithium plating potential determination module, configured to determine the lithium plating potential of the lithium-ion battery after confirming that the lithium-ion battery has lithium plating according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve.

[0032] According to another aspect of the present invention, there is provided an electronic device, the electronic device comprising:

[0033] At least one processor; and

[0034] A memory communicatively connected to the at least one processor; wherein,

[0035] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for determining the lithium plating potential of a lithium-ion battery according to any embodiment of the present invention.

[0036] The method for determining the lithium plating potential of a lithium-ion battery provided by the embodiments of the present invention, by real-time collecting voltage data and capacity data of the lithium-ion battery during a charging test, draws a first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and a second-order differential d 2 Q / dV 2 -V curve, and determines the lithium plating state of the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve, and determines the lithium plating potential of the lithium-ion battery after confirming that the lithium-ion battery has lithium plating, solving the problems of long time consumption and low accuracy in lithium plating detection of lithium-ion batteries, and at the same time being able to clearly and intuitively see the true lithium plating potential of the lithium-ion battery.

[0037] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0039] Figure 1 is a flowchart of a method for determining the lithium plating potential of a lithium-ion battery provided by an embodiment of the present invention;

[0040] Figure 2 is a preset charging test chart of a lithium-ion battery at different charging rates and different charging temperatures provided by an embodiment of the present invention;

[0041] Figure 3 is a flowchart of another method for determining the lithium plating potential of a lithium-ion battery provided by an embodiment of the present invention;

[0042] Figure 4 is the first-order and second-order differential curves of the 1C charging capacity at 25°C provided by an embodiment of the present invention;

[0043] Figure 5 is a flowchart of yet another method for determining the lithium plating potential of a lithium-ion battery provided by an embodiment of the present invention;

[0044] Figure 6 is the first-order and second-order differential curves of the 1.5C charging capacity at 25°C provided by an embodiment of the present invention;

[0045] Figure 7 is the first-order and second-order differential curves of the 0.1C charging capacity at -10°C provided by an embodiment of the present invention;

[0046] Figure 8 is a schematic structural diagram of a device for determining the lithium plating potential of a lithium-ion battery provided by an embodiment of the present invention;

[0047] Figure 9 shows a schematic structural diagram of an electronic device that can be used to implement the embodiments of the present invention. Detailed Embodiments

[0048] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0049] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order different from those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0050] The embodiment of the present invention provides a method for determining the lithium plating potential of a lithium-ion battery. Figure 1 is a flowchart of a method for determining the lithium plating potential of a lithium-ion battery provided by an embodiment of the present invention. Refer to Figure 1 , the method for determining the lithium plating potential of a lithium-ion battery includes:

[0051] S110. Perform a charge test on the lithium-ion battery and collect voltage and capacity data of the lithium-ion battery during the charge test; wherein, during the same charge test, the charge rate is the same and the charge temperature is the same.

[0052] Among them, the lithium-ion battery can be a lithium iron phosphate battery, a ternary lithium battery, a lithium manganate battery, etc., and the embodiments of the present invention do not limit this. The lithium-ion battery can include a soft-pack, square, cylindrical or special-shaped battery cell. Specifically, voltage data of the lithium-ion battery during the charging test can be collected by a voltage sensor. Exemplarily, the voltage sensor can be a capacitive voltage sensor, a resistive voltage sensor, etc., and the embodiments of the present invention do not limit this. Among them, the voltage acquisition accuracy can be 0.1 mV, and the time interval for collecting voltage data can be 10 ms, 20 ms, 30 ms, etc., and the embodiments of the present invention do not limit this, as long as the time interval for collecting voltage data is not greater than 1 s. If the time interval for collecting voltage data is too large, it will affect the curve drawing of voltage and capacity, and further affect the accuracy of the lithium precipitation potential of the lithium-ion battery. The capacity can be understood as the charge capacity of the lithium-ion battery during the charging test. The time interval for collecting charge capacity data can be the same as the time interval for collecting voltage data. The capacity data of the lithium-ion battery during the charging test can be collected by a capacity sensor, or the current data of the lithium-ion battery during the charging test can be measured by a current sensor and calculated by the formula Q = I * t, where Q is understood as the charge capacity of the lithium-ion battery during the charging test, I is the test current of the lithium-ion battery during the charging test, and t is the charging duration.

[0053] Specifically, during the same charging test, the charging rate and charging temperature should be kept the same. In order to clearly and intuitively see the lithium precipitation potential of the lithium-ion battery under different charging rates and different charging temperatures, the embodiments of the present invention have made a preset charging test chart of the lithium-ion battery under different charging rates and different charging temperatures. Through the preset charging test chart, the rate at which the lithium-ion battery will definitely not precipitate lithium can be estimated, and at the same time, the maximum allowable charging rate of the lithium-ion battery can be designed according to the preset charging test chart. The charging temperature and charging rate in the preset charging test chart can be adjusted according to actual needs. Exemplarily, if the lithium-ion battery is used in a low-temperature environment for a long time, the test temperature of the lithium-ion battery can be set relatively low; if the lithium-ion battery is used in a high-temperature environment for a long time, the test temperature of the lithium-ion battery can be set relatively high, and the embodiments of the present invention do not limit this; if it is required to estimate the rate at which the lithium-ion battery will definitely not precipitate lithium very accurately, the charging rate of the lithium-ion battery needs to be designed more densely; if it is required that the accuracy of estimating the rate at which the lithium-ion battery will definitely not precipitate lithium is not high, the density of the number of charging rates of the lithium-ion battery can be designed moderately, and the embodiments of the present invention do not limit this. Figure 2 is the preset charging test chart of the lithium-ion battery under different charging rates and different charging temperatures provided by the embodiments of the present invention. Refer to Figure 2, charging tests of lithium-ion batteries can be carried out at the same charging temperature but different charging rates. Exemplarily, under the condition of keeping the ambient temperature constant at 25°C, charging tests of lithium-ion batteries are carried out at charging rates of 0.1C, 0.33C, 0.5C, 1.0C, 1.5C, and 2.0C respectively. Among them, the same charging temperature can be achieved by a temperature control box; charging tests of lithium-ion batteries can also be carried out at the same charging rate but different charging temperatures. Exemplarily, under the condition of keeping the charging rate at 0.5C unchanged, charging tests of lithium-ion batteries are carried out in environments with external temperatures of -10°C, 0°C, 10°C, 25°C, and 35°C respectively. The embodiments of the present invention do not limit this.

[0054] S120. Differentiate the voltage and capacity data to obtain the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve.

[0055] Exemplarily, according to the measured voltage and capacity data of the lithium-ion battery, the relationship curve between the voltage and capacity of the lithium-ion battery can be plotted. According to the plotted relationship curve between the voltage and capacity of the lithium-ion battery, the slope value corresponding to each point in the curve can be obtained. Combining the voltage value V corresponding to each point, the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery can be obtained. Similarly, according to the plotted first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery, the slope value corresponding to each point in the curve can be obtained. Combining the voltage value V corresponding to each point, the second-order differential d 2 Q / dV 2-V curve. It is also possible to process the measured voltage and capacity data of the lithium-ion battery. Taking the voltage value of the nth data point as an example, the specific description is as follows: Add a fixed voltage interval to the voltage value of the nth data point to obtain the voltage value of the (n + 1)th data point. Here, the fixed voltage interval can be any value from 1 mV to 5 mV, and the embodiments of the present invention do not limit this. Obtain the capacity data Q1 corresponding to the voltage value of the (n + 1)th data point through an accurate search method; then subtract the fixed voltage interval from the voltage value of the nth data point to obtain the voltage value of the (n - 1)th data point, and obtain the capacity data Q2 corresponding to the voltage value of the (n - 1)th data point through an accurate search method; subtract the capacity data Q2 corresponding to the voltage value of the (n - 1)th data point from the capacity data Q1 corresponding to the voltage value of the (n + 1)th data point to obtain dQ, and add the two fixed voltage intervals to obtain dV. Process all the data in sequence to obtain a series of dV and dQ data, then divide dQ by dV to obtain another data dQ / dV. Then, taking dQ / dV as the ordinate and the voltage corresponding to each dQ / dV data as the abscissa, the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery can be obtained. Similarly, add a fixed voltage interval to the voltage value of the nth data point to obtain the voltage value of the (n + 1)th data point, and obtain the dQ / dV data m1 corresponding to the voltage value of the (n + 1)th data point through an accurate search method; then subtract the fixed voltage interval from the voltage value of the nth data point to obtain the voltage value of the (n - 1)th data point, and obtain the dQ / dV data m2 corresponding to the voltage value of the (n - 1)th data point through an accurate search method; subtract the dQ / dV data m2 corresponding to the voltage value of the (n - 1)th data point from the dQ / dV data m1 corresponding to the voltage value of the (n + 1)th data point to obtain d(dQ / dV), and add the two fixed voltage intervals to obtain dV. Process all the data in sequence to obtain a series of d(dQ / dV) data, then divide d(dQ / dV) by dV to obtain another data d 2 Q / dV 2 and then, taking d 2 Q / dV 2 as the ordinate and the voltage corresponding to each d 2 Q / dV 2 data as the abscissa, the second-order differential d 2 Q / dV 2 -V curve of the charging capacity of the lithium-ion battery can be obtained.

[0056] S130. According to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2The -V curve is used to determine the lithium plating state of the lithium-ion battery and to determine the lithium plating potential of the lithium-ion battery.

[0057] Specifically, the first-order differential dQ / dV-V curve is susceptible to the influence of the charging rate and the charging temperature. As the charging rate gradually increases or the charging temperature gradually decreases, some characteristic peaks in the first-order differential curve gradually merge to form a wider characteristic peak. When the charging rate of the lithium-ion battery is less than the preset charging rate and the charging temperature is greater than the preset temperature, it indicates that the characteristic peaks in the first-order differential dQ / dV-V curve of the charging capacity at this time are relatively obvious. Among them, the preset charging rate and the preset temperature can be set according to the actual situation. The lithium plating state of the lithium-ion battery can be judged through the first-order differential dQ / dV-V curve of the charging capacity. If it is confirmed that the lithium-ion battery has lithium plating, the lithium plating potential of the lithium-ion battery can be determined through the first-order differential dQ / dV-V curve of the charging capacity, or the second-order differential d 2 Q / dV 2 -V curve can also be used to determine the lithium plating potential of the lithium-ion battery, and the embodiments of the present invention do not limit this. When the charging rate of the lithium-ion battery is greater than the preset charging rate and / or the charging temperature is less than the preset temperature, it indicates that the characteristic peaks in the first-order differential dQ / dV-V curve of the charging capacity at this time are not obvious or there is a phenomenon of voltage characteristic peak fusion. It is difficult to judge the lithium plating state of the lithium-ion battery through the first-order differential dQ / dV-V curve of the charging capacity, and it is necessary to rely on the second-order differential d 2 Q / dV 2 -V curve to determine the lithium plating state of the lithium-ion battery. If it is confirmed that the lithium-ion battery has lithium plating, the second-order differential d 2 Q / dV 2 -V curve is used again to determine the lithium plating potential of the lithium-ion battery.

[0058] The method for determining the lithium plating potential of the lithium-ion battery provided by the embodiments of the present invention collects the voltage data and capacity data of the lithium-ion battery during the charging test in real time, draws the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve of the charging capacity, and judges the lithium plating state of the lithium-ion battery and determines the lithium plating potential of the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve, which solves the problems of long time consumption and low accuracy in lithium plating detection of lithium-ion batteries, and can clearly and intuitively show the true lithium plating potential of lithium-ion batteries.

[0059] Figure 3 is a flowchart of another method for determining the lithium plating potential of the lithium-ion battery provided by the embodiments of the present invention. Refer toFigure 3 When the charging rate of the lithium-ion battery is less than the preset charging rate and the charging temperature is greater than the preset temperature, the lithium plating state of the lithium-ion battery is judged according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve, and the lithium plating potential of the lithium-ion battery is determined. The method for determining the lithium plating potential of the lithium-ion battery includes:

[0060] S210. Perform a charging test on the lithium ions, and collect the voltage and capacity data of the lithium-ion battery during the charging test; wherein, during the same charging test, the charging rate is the same and the charging temperature is the same.

[0061] S220. Differentiate the voltage and capacity data to obtain the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve.

[0062] S230. Judge whether the lithium-ion battery has lithium plating according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery.

[0063] Specifically, when the lithium-ion battery undergoes a lithium plating reaction, a new voltage platform representing lithium plating will be added, and the voltage platform representing lithium plating corresponds to a lithium plating characteristic peak. When the charging rate of the lithium-ion battery is less than the preset charging rate and the charging temperature is greater than the preset temperature, it means that the characteristic peak in the first-order differential dQ / dV-V curve of the charging capacity at this time is relatively obvious. The lithium plating state of the lithium-ion battery, that is, whether the lithium-ion battery has lithium plating, can be judged through the first-order differential dQ / dV-V curve of the charging capacity. Exemplarily, taking a lithium iron phosphate battery with a charging temperature of 25°C and a charging rate of 1C as an example, whether the lithium-ion battery has lithium plating is described in detail as follows:

[0064] Figure 4 is the first-order and second-order differential curves of the 1C charging capacity at 25°C provided by the embodiment of the present invention. As Figure 4 shown, the dotted line is the first-order differential dQ / dV-V curve of the 1C charging capacity of the lithium iron phosphate battery at 25°C, and the solid line is the second-order differential d 2 Q / dV 2 -V curve of the 1C charging capacity of the lithium iron phosphate battery at 25°C. Normally, under the condition that the lithium iron phosphate battery does not have lithium plating, there will be four voltage platforms, and then the first-order differential dQ / dV-V curve of the charging capacity corresponds to four peaks. If the lithium iron phosphate battery has lithium plating, a new voltage platform will be added, and then a fifth peak will appear in the first-order differential dQ / dV-V curve of the charging capacity. As Figure 4As shown, five peaks can be obtained from the first-order differential dQ / dV-V curve of the 1C charge capacity of the lithium iron phosphate battery at 25°C, that is, it can be determined that there is a lithium plating characteristic peak in the phase change peak of the first-order differential dQ / dV-V curve of the charge capacity under the conditions of 25°C and 1C charge rate, and it is determined that the lithium iron phosphate battery has lithium plating.

[0065] S240. If lithium plating occurs in the lithium-ion battery, then according to the second-order differential d 2 Q / dV 2 -V curve of the charge capacity of the lithium-ion battery, the lithium plating potential of the lithium-ion battery is determined.

[0066] Specifically, as Figure 4 shown, at the fifth peak 1 in the first-order differential dQ / dV-V curve of the 1C charge capacity of the lithium iron phosphate battery at 25°C, find the corresponding second-order differential d 2 Q / dV 2 -V curve of the 1C charge capacity of the lithium iron phosphate battery at 25°C, and find the maximum value point of the lithium plating characteristic peak. The voltage value corresponding to the maximum value point of the lithium plating characteristic peak is the lithium plating potential of the lithium iron phosphate battery.

[0067] The method for determining the lithium plating potential of the lithium-ion battery provided by the embodiment of the present invention, when the charge rate of the lithium-ion battery is less than the preset charge rate and the charge temperature is greater than the preset temperature, determines whether the lithium-ion battery has lithium plating according to the first-order differential dQ / dV-V curve of the charge capacity of the lithium-ion battery. If the lithium-ion battery has lithium plating, then according to the second-order differential charge capacity d 2 Q / dV 2 -V curve of the lithium-ion battery to determine the lithium plating potential of the lithium-ion battery, that is, when the characteristic peak of the first-order curve is obvious, it is determined whether the lithium-ion battery has lithium plating through the first-order differential dQ / dV-V curve of the charge capacity, which can not only clearly and intuitively see the true lithium plating potential of the lithium-ion battery, but also be convenient, fast and highly accurate.

[0068] Figure 5 is a flowchart of another method for determining the lithium plating potential of the lithium-ion battery provided by the embodiment of the present invention. As Figure 5 shown, when the charge rate of the lithium-ion battery is greater than the preset charge rate and / or the charge temperature is less than the preset temperature, determine the lithium plating state of the lithium-ion battery and determine the lithium plating potential of the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charge capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve of the charge capacity of the lithium-ion battery. The method for determining the lithium plating potential of the lithium-ion battery includes:

[0069] S310. Conduct a charging test on lithium ions and collect the voltage and capacity data of the lithium-ion battery during the charging test. Among them, during the same charging test, the charging rate is the same and the charging temperature is the same.

[0070] S320. Differentiate the voltage and capacity data to obtain the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve of the charging capacity.

[0071] S330. Based on the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and combined with the second-order differential d 2 Q / dV 2 -V curve of the charging capacity, determine whether lithium plating occurs in the lithium-ion battery.

[0072] Specifically, when the charging rate of the lithium-ion battery is greater than the preset charging rate and / or the charging temperature is lower than the preset temperature, it indicates that the characteristic peaks in the first-order differential dQ / dV-V curve of the charging capacity at this time are not obvious or the characteristic peaks in the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery will show a fusion phenomenon. It is difficult to judge the lithium plating state of the lithium-ion battery through the first-order differential dQ / dV-V curve of the charging capacity. At this time, it is necessary to combine the second-order differential d 2 Q / dV 2 -V curve of the charging capacity to judge whether lithium plating occurs in the lithium-ion battery. Exemplarily, under the condition that the charging rate is greater than the preset charging rate, taking a lithium iron phosphate battery with a charging temperature of 25°C and a charging rate of 1.5C as an example, a detailed description of whether lithium plating occurs in the lithium-ion battery is as follows:

[0073] Figure 6 are the first-order and second-order differential curves of the 1.5C charging capacity at 25°C provided by the embodiment of the present invention. As Figure 6 shown, the dotted line is the first-order differential dQ / dV-V curve of the 1.5C charging capacity of the lithium iron phosphate battery at 25°C, and the solid line is the second-order differential d 2 Q / dV 2 -V curve of the 1.5C charging capacity of the lithium iron phosphate battery at 25°C. Normally, under the condition that no lithium plating occurs in the lithium iron phosphate battery, there will be four voltage platforms, and then the first-order differential curve of the charging capacity corresponds to four peaks. However, because the charging rate at this time is greater than the preset charging rate, the characteristic peaks in the first-order differential dQ / dV-V curve of the charging capacity have a fusion phenomenon. As Figure 6 shown, the characteristic peaks in the first-order differential dQ / dV-V curve of the 1.5C charging capacity of the lithium iron phosphate battery at 25°C are not obvious. At this time, combined with the second-order differential d of the 1.5C charging capacity of the lithium iron phosphate battery at 25°C2 Q / dV 2 -V curve is used to judge whether lithium plating occurs in the lithium iron phosphate battery. Since each characteristic peak appears in the first-order differential dQ / dV-V curve, the second-order differential d 2 Q / dV 2 -V curve will correspondingly have a maximum point. By observing that there are 5 maximum points in the second-order differential d 2 Q / dV 2 -V curve, it can be judged that lithium plating occurs in the lithium iron phosphate battery under the conditions of 25°C and a charging rate of 1.5C.

[0074] When the charging rate is too high, due to the more obvious phenomenon of the fusion of characteristic peaks in the first-order differential dQ / dV-V curve of the charging capacity, it affects the number of peaks in the second-order differential d 2 Q / dV 2 -V curve. At this time, it is not applicable to judge whether lithium plating occurs in the lithium-ion battery by combining the first-order differential dQ / dV-V curve of the charging capacity with the second-order differential d 2 Q / dV 2 -V curve of the charging capacity of the lithium-ion battery by the number of characteristic peaks. At different charging temperatures, by combining the first-order differential dQ / dV-V curve of the charging capacity with the second-order differential d 2 Q / dV 2 -V curve method to determine whether lithium plating occurs in the lithium-ion battery is applicable to different charging rate ranges. Exemplarily, referring to Figure 6 , under the conditions of a charging temperature of 25°C and a charging rate less than 1.5C, it is possible to determine whether lithium plating occurs in the lithium-ion battery by combining the first-order differential dQ / dV-V curve of the charging capacity with the second-order differential d 2 Q / dV 2 -V curve of the charging capacity of the lithium-ion battery. Under the conditions of a charging temperature of 25°C and a charging rate greater than 1.5C, it is not applicable to determine whether lithium plating occurs in the lithium-ion battery by combining the first-order differential dQ / dV-V curve of the charging capacity with the second-order differential d 2 Q / dV 2 -V curve of the charging capacity of the lithium-ion battery.

[0075] Under the condition that the charging temperature is less than the preset temperature, taking the lithium iron phosphate battery with a charging temperature of -10°C and a charging rate of 0.1C as an example, a detailed description of whether lithium plating occurs in the lithium-ion battery is as follows:

[0076] Figure 7 are the first-order and second-order differential curves of the 0.1C charging capacity at -10°C provided by the embodiments of the present invention, as shown in Figure 7As shown, the dashed line is the first-order differential dQ / dV-V curve of the charging capacity of the lithium iron phosphate battery at -10°C with a 0.1C charging rate, and the solid line is the second-order differential d 2 Q / dV 2 -V curve. Under normal circumstances, when no lithium plating occurs in the lithium iron phosphate battery, there will be four voltage platforms, and thus the first-order differential curve of the charging capacity corresponds to four peaks. However, because the charging temperature is less than the preset temperature at this time, the characteristic peaks in the first-order differential dQ / dV-V curve of the charging capacity show a phenomenon of fusion. As Figure 7 shown, the characteristic peaks in the first-order differential dQ / dV-V curve of the charging capacity of the lithium iron phosphate battery at -10°C with a 0.1C charging rate are not obvious. At this time, combined with the second-order differential d 2 Q / dV 2 -V curve, it is judged whether lithium plating occurs in the lithium iron phosphate battery. Since every time a characteristic peak appears in the first-order differential dQ / dV-V curve, the second-order differential d 2 Q / dV 2 -V curve will correspondingly have a maximum point. By the fact that 5 maximum points appear in the second-order differential d 2 Q / dV 2 -V curve, it can be judged that the lithium iron phosphate battery undergoes lithium plating under the conditions of -10°C and a 0.1C charging rate.

[0077] When the charging temperature is too low, referring to Figure 6 , at this time, the phenomenon of more obvious fusion of the characteristic peaks in the first-order differential dQ / dV-V curve of the charging capacity occurs, which affects the number of inflection points of the second-order differential d 2 Q / dV 2 -V curve. At this time, it is not applicable to judge whether lithium plating occurs in the lithium ion battery by combining the first-order differential dQ / dV-V curve of the charging capacity with the second-order differential d 2 Q / dV 2 -V curve of the charging capacity of the lithium ion battery and determining whether lithium plating occurs in the lithium ion battery by the number of characteristic peaks. At different charging temperatures, the method of combining the first-order differential dQ / dV-V curve of the charging capacity with the second-order differential d 2 Q / dV 2 -V curve of the charging capacity of the lithium ion battery to determine whether lithium plating occurs is applicable to different charging rate ranges. Exemplarily, under the conditions of a charging temperature of -10°C and a charging rate less than 0.1C, it is possible to combine the first-order differential dQ / dV-V curve of the charging capacity with the second-order differential d 2 Q / dV 2The method of using the dQ / dV-V curve to determine whether lithium plating occurs in a lithium-ion battery is not applicable under the conditions of a charging temperature of -10 °C and a charging rate greater than 0.1C by combining the first-order differential dQ / dV-V curve of the charging capacity with the second-order differential d 2 Q / dV 2 -V curve to determine whether lithium plating occurs in a lithium-ion battery.

[0078] S340. If lithium plating occurs in the lithium-ion battery, then according to the second-order differential d 2 Q / dV 2 -V curve of the lithium-ion battery to determine the lithium plating potential.

[0079] Specifically, as Figure 6 and Figure 7 shown, the voltage value corresponding to the maximum point of the second-order differential d 2 Q / dV 2 -V curve of the lithium iron phosphate battery is the lithium plating potential of the lithium iron phosphate battery. Exemplarily, at Figure 6 the voltage value corresponding to the 5th characteristic peak 2 shown is the lithium plating potential of the lithium iron phosphate battery, and at Figure 7 the voltage value corresponding to the 5th characteristic peak 3 shown is the lithium plating potential of the lithium iron phosphate battery.

[0080] For the method for determining the lithium plating potential of a lithium-ion battery provided by an embodiment of the present invention, when the charging rate of the lithium-ion battery is greater than a preset charging rate and / or the charging temperature is less than a preset temperature, according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery, and in combination with the second-order differential d 2 Q / dV 2 -V curve of the charging capacity of the lithium-ion battery to determine whether lithium plating occurs in the lithium-ion battery. If lithium plating occurs in the lithium-ion battery, then according to the second-order differential d 2 Q / dV 2 -V curve of the lithium-ion battery to determine the lithium plating potential of the lithium-ion battery, that is, in the case where the characteristic peaks of the first-order curve are not obvious or appear to merge, by combining the first-order differential dQ / dV-V curve of the charging capacity with the second-order differential d 2 Q / dV 2 -V curve to determine whether lithium plating occurs in the lithium-ion battery, which can not only clearly and intuitively show the true lithium plating potential of the lithium-ion battery, but also be convenient, fast, and have high accuracy.

[0081] Optionally, referring to Figure 4 , Figure 6 and Figure 7 , according to the second-order differential d 2 Q / dV 2- The determination of the lithium plating potential of a lithium-ion battery by the V curve includes:

[0082] Determine the second derivative d 2 Q / dV 2 - The voltage corresponding to the maximum point of the lithium plating characteristic peak in the V curve;

[0083] Take the second derivative d 2 Q / dV 2 - The voltage corresponding to the maximum point of the lithium plating characteristic peak in the V curve is determined as the lithium plating potential of the lithium-ion battery.

[0084] Exemplarily, as Figure 4 shown, at the 5th peak in the first derivative dQ / dV-V curve of the 1C charge capacity at 25°C, find the corresponding second derivative d 2 Q / dV 2 - The maximum point of the lithium plating characteristic peak in the V curve, and the voltage value corresponding to the maximum point of the lithium plating characteristic peak is the lithium plating potential of the lithium iron phosphate battery; as Figure 6 and Figure 7 shown, the voltage value corresponding to the maximum point of the lithium plating characteristic peak in the second derivative d 2 Q / dV 2 - The V curve of the lithium iron phosphate battery is the lithium plating potential of the lithium iron phosphate battery. Since the sharpness of the peak in the second derivative d 2 Q / dV 2 - The V curve is relatively high, which is convenient for determining the position of the peak point. Therefore, the voltage corresponding to the maximum point of the lithium plating characteristic peak in the second derivative d 2 Q / dV 2 - The V curve is determined as the lithium plating potential of the lithium-ion battery, which can further clearly and intuitively show the true lithium plating potential of the lithium-ion battery and improve the accuracy.

[0085] Optionally, as Figure 2 shown, for the charging test of lithium ions, the method for determining the lithium plating potential of a lithium-ion battery includes:

[0086] According to the combination relationship between the charging temperature and the charging rate in the preset charging test chart, conduct charging tests on the lithium-ion battery at different charging rates at multiple charging temperatures; wherein, the charging rate at each charging temperature includes at least the charging rate without lithium plating and the maximum allowable continuous charging rate; during each charging test, fully charge the lithium-ion battery to the cut-off voltage according to the charging rate.

[0087] Exemplarily, under the condition that the ambient temperature is kept constant at 25°C, charging tests are respectively carried out on the lithium-ion battery at charging rates of 0.1C, 0.33C, 0.5C, 1.0C, 1.5C, and 2.0C. Among them, the same charging temperature can be achieved through a temperature control box; charging tests can also be carried out on the lithium-ion battery at the same charging rate but different charging temperatures. Exemplarily, under the condition that the charging rate is kept constant at 0.5C, the lithium-ion battery is charged at ambient temperatures of -10°C, 0°C, 10°C, 25°C, and 35°C respectively. The embodiments of the present invention do not limit this. Specifically, the charging rate at each charging temperature at least includes the charging rate without lithium deposition and the maximum allowable continuous charging rate. It can be understood that by presetting a charging test chart, the rate at which the lithium-ion battery will definitely not deposit lithium can be estimated, and at the same time, the maximum allowable charging rate of the lithium-ion battery can be designed according to the preset charging test chart. Among them, during each charging test, the lithium-ion battery is fully charged to the cut-off voltage according to the charging rate. Exemplarily, the lithium iron phosphate battery uses 3.55V - 3.65V as the cut-off voltage, and the ternary lithium battery uses 4.2V - 4.35V as the cut-off voltage.

[0088] Optionally, the method for determining the lithium deposition potential of the lithium-ion battery further includes:

[0089] At the same charging rate, obtain the second derivative d 2 Q / dV 2 -V curve of the charging capacity corresponding to different charging temperatures of the lithium-ion battery to determine the lithium deposition potential of the lithium-ion battery at different charging temperatures; thus, it is convenient to determine the appropriate charging temperature at each charging rate and the appropriate charging stop potential at different charging temperatures.

[0090] And / or, at the same charging temperature, obtain the second derivative d 2 Q / dV 2 -V curve of the charging capacity corresponding to different charging rates of the lithium-ion battery to determine the lithium deposition potential of the lithium-ion battery at different charging rates, so as to facilitate determining the appropriate charging rate at each charging temperature and the appropriate charging stop potential at different charging rates.

[0091] Optionally, the charging temperature range in which the lithium-ion battery is allowed to continuously charge includes -30°C to 55°C; the charging rate range in which the lithium-ion battery is allowed to continuously charge includes 0.01C to 2C;

[0092] During the charging test of the lithium-ion battery, the charging voltage acquisition time interval is less than or equal to 1S, and the charging voltage acquisition accuracy is less than or equal to 1mV.

[0093] Specifically, if the time interval for collecting voltage data is too large, it will affect the plotting of the voltage and capacity curves, and further affect the accuracy of the lithium plating potential of the lithium-ion battery. When the charging voltage acquisition time interval is less than or equal to 1S and the charging voltage acquisition accuracy is less than or equal to 1mV, the accuracy of the lithium plating potential of the lithium-ion battery can be ensured.

[0094] Figure 8 FIG. 4 is a schematic structural diagram of a device for determining the lithium plating potential of a lithium-ion battery according to an embodiment of the present invention. As Figure 8 shown, the device 500 for determining the lithium plating potential of a lithium-ion battery includes:

[0095] A data acquisition module 510, configured to collect voltage and capacity data of the lithium-ion battery during the charging test of the lithium-ion battery; wherein, during the same charging test, the charging rate is the same and the charging temperature is the same;

[0096] A differential processing module 520, configured to perform differential processing on the voltage and capacity data to obtain a first-order differential dQ / dV-V curve of the charging capacity and a second-order differential d2Q / dV2-V curve of the charging capacity of the lithium-ion battery;

[0097] A lithium plating potential determination module 530, configured to determine the lithium plating state of the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity and the second-order differential d 2 Q / dV 2 -V curve of the lithium-ion battery, and determine the lithium plating potential of the lithium-ion battery after confirming that the lithium-ion battery has lithium plating.

[0098] Further, when the charging rate of the lithium-ion battery is less than the preset charging rate and the charging temperature is greater than the preset temperature, determine the lithium plating state of the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity and the second-order differential d 2 Q / dV 2 -V curve of the lithium-ion battery, and determine the lithium plating potential of the lithium-ion battery after confirming that the lithium-ion battery has lithium plating. The lithium plating potential determination module 530 includes:

[0099] A first-order judgment unit: configured to judge whether the lithium-ion battery has lithium plating according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery;

[0100] A lithium plating determination unit: configured to, if the lithium-ion battery has lithium plating, determine the lithium plating potential of the lithium-ion battery according to the second-order differential d 2 Q / dV 2 -V curve of the lithium-ion battery.

[0101] Further, when the charging rate of the lithium-ion battery is greater than the preset charging rate and / or the charging temperature is lower than the preset temperature, the lithium plating state of the lithium-ion battery is determined according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve, and after confirming that the lithium-ion battery has lithium plating, the lithium plating potential of the lithium-ion battery is determined. The lithium plating potential determination module 530 includes:

[0102] Combined judgment unit: According to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery, and combined with the second-order differential d 2 Q / dV 2 -V curve to judge whether the lithium-ion battery has lithium plating;

[0103] Lithium plating determination unit: If the lithium-ion battery has lithium plating, then according to the second-order differential d 2 Q / dV 2 -V curve to determine the lithium plating potential of the lithium-ion battery.

[0104] Further, the first-order judgment unit is specifically used for:

[0105] Judge whether there is a lithium plating characteristic peak in the phase change peak of the first-order differential dQ / dV-V curve of the charging capacity;

[0106] If it exists, it is determined that the lithium-ion battery has lithium plating; among them, when the lithium-ion battery undergoes a lithium plating reaction, a voltage platform representing lithium plating will be newly added, and the voltage platform representing lithium plating corresponds to the lithium plating characteristic peak.

[0107] Further, the lithium plating determination unit is specifically used for:

[0108] Determine the voltage corresponding to the maximum value point of the lithium plating characteristic peak in the second-order differential d 2 Q / dV 2 -V curve;

[0109] The voltage corresponding to the maximum value point of the lithium plating characteristic peak in the second-order differential d 2 Q / dV 2 -V curve is determined as the initial lithium plating potential of the lithium-ion battery.

[0110] Further, the combined test unit is specifically used for:

[0111] According to the combined relationship between the charging temperature and the charging rate in the preset charging test diagram, the lithium-ion battery is subjected to charging tests at different charging rates under multiple charging temperatures; wherein, the charging rates at each charging temperature at least include the charging rate at which lithium precipitation is estimated to never occur and the maximum allowable continuous charging rate; during each charging test, the lithium-ion battery is fully charged to the cut-off voltage according to the test charging rate.

[0112] Further, the combined test unit further includes:

[0113] At the same charging rate, obtain the second-order differential curve of the charging capacity corresponding to different charging temperatures of the lithium battery to determine the lithium precipitation potential of the lithium-ion battery at different temperatures;

[0114] And / or, at the same charging temperature, obtain the second-order differential curve of the charging capacity corresponding to different charging rates of the lithium battery to determine the lithium precipitation potential of the lithium-ion battery at different charging rates.

[0115] Further, the temperature range in which the lithium-ion battery is allowed to continuously charge includes -30°C to 55°C; the charging rate range in which the lithium-ion battery is allowed to continuously charge includes 0.01C to 2C;

[0116] During the charging test of the lithium-ion battery, the charging voltage acquisition time interval is less than or equal to 1S, and the charging voltage acquisition accuracy is less than or equal to 1mV.

[0117] Further, the types of lithium-ion batteries include lithium iron phosphate batteries, ternary lithium batteries, and lithium manganate batteries;

[0118] The lithium-ion battery includes a soft-pack, square, cylindrical, or special-shaped battery cell.

[0119] The device for determining the lithium precipitation potential of the lithium-ion battery provided by the embodiments of the present invention can execute the method for determining the lithium precipitation potential of the lithium-ion battery provided by any embodiment of the present invention, and has the corresponding functional modules and beneficial effects for executing the method.

[0120] Figure 9 The structural schematic diagram of the electronic device that can be used to implement the embodiments of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as, laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as, personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are only examples and are not intended to limit the implementation of the present invention described herein and / or claimed.

[0121] AsFigure 9 As shown, the electronic device 10 includes at least one processor 11 and a memory communicatively connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc. The memory stores a computer program executable by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0122] Multiple components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a magnetic disk, an optical disc, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0123] The processor 11 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the processor 11 include but are not limited to a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the method for determining the lithium plating potential of a lithium-ion battery.

[0124] In some embodiments, the method for determining the lithium plating potential of a lithium-ion battery can be implemented as a computer program tangibly embodied in a computer-readable storage medium, such as the storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the method for determining the lithium plating potential of a lithium-ion battery described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to execute the method for determining the lithium plating potential of a lithium-ion battery by any other appropriate means (e.g., by means of firmware).

[0125] The various embodiments of the systems and techniques described above in this specification can be implemented in digital electronic circuitry, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems-on-chip (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include: being implemented in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be a special-purpose or general-purpose programmable processor that receives data and instructions from, and transmits data and instructions to, a storage system, at least one input device, and at least one output device.

[0126] The computer program for implementing the method for determining the lithium plating potential of a lithium-ion battery of the present invention can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general purpose computer, a special purpose computer, or other programmable data processing apparatus, such that the computer programs, when executed by the processor, cause the functions / operations specified in the flowchart(s) and / or block diagram(s) to be implemented. The computer program can be executed entirely on the machine, partly on the machine, as a stand-alone software package partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0127] In the context of the present invention, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, the computer-readable storage medium can be a machine-readable signal medium. More specific examples of the machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0128] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or a trackball) through which the user can provide input to the electronic device. Other kinds of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0129] The systems and techniques described herein can be implemented in a computing system including backend components (e.g., as a data server), or a computing system including middleware components (e.g., an application server), or a computing system including frontend components (e.g., a user computer having a graphical user interface or a web browser through which the user can interact with an implementation of the systems and techniques described herein), or a computing system including any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected to each other by digital data communication in any form or medium (e.g., a communication network). Examples of communication networks include: local area network (LAN), wide area network (WAN), blockchain network, and the Internet.

[0130] The computing system can include a client and a server. The client and the server are generally far from each other and typically interact through a communication network. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or a cloud host, which is a host product in the cloud computing service system and solves the defects of difficult management and weak business scalability existing in traditional physical hosts and VPS services.

[0131] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps recited in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and this is not limited herein.

[0132] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for determining the lithium plating potential of a lithium-ion battery, characterized in that, Including: Conduct a charging test on a lithium-ion battery and collect voltage and capacity data of the lithium-ion battery during the charging test; wherein, during the same charging test, the charging rate is the same and the charging temperature is the same; Differentiate the voltage and the capacity data to obtain the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve; According to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve, determine the lithium plating state of the lithium-ion battery and determine the lithium plating potential of the lithium-ion battery; When the charging rate of the lithium-ion battery is less than a preset charging rate and the charging temperature is greater than a preset temperature, judging the lithium plating state of the lithium-ion battery and determining the lithium plating potential of the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve, including: Judge whether lithium plating occurs in the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery; If lithium plating occurs in the lithium-ion battery, the lithium plating potential of the lithium-ion battery is determined according to the second derivative d 2 Q / dV 2 -V curve of the charging capacity of the lithium-ion battery; When the charging rate of the lithium-ion battery is greater than a preset charging rate and / or the charging temperature is lower than a preset temperature, according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve to determine the lithium plating state of the lithium-ion battery and determine the lithium plating potential of the lithium-ion battery, including: Based on the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and in combination with the second-order differential d 2 Q / dV 2 -V curve to determine whether lithium plating occurs in the lithium-ion battery; If lithium plating occurs in the lithium-ion battery, the lithium plating potential of the lithium-ion battery is determined according to the second derivative d 2 Q / dV 2 -V curve of the charging capacity of the lithium-ion battery.

2. The method for determining the lithium plating potential of a lithium-ion battery according to claim 1, wherein Judging whether lithium plating occurs in the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery includes: Judge whether there is a lithium plating characteristic peak in the phase change peak of the first-order differential dQ / dV-V curve of the charging capacity; If it exists, it is determined that lithium plating occurs in the lithium-ion battery; wherein, when the lithium-ion battery undergoes a lithium plating reaction, a voltage plateau representing lithium plating will be newly added, and the voltage plateau representing lithium plating corresponds to the lithium plating characteristic peak.

3. The method for determining the lithium plating potential of a lithium-ion battery according to claim 1, wherein, Determine the lithium plating potential of the lithium-ion battery according to the second-order differential d 2 Q / dV 2 -V curve, including: Determine the second derivative d 2 Q / dV 2 of the charging capacity, which is the voltage corresponding to the maximum point of the lithium plating characteristic peak in the -V curve; Determine the voltage corresponding to the maximum point of the lithium plating characteristic peak in the second-order differential d 2 Q / dV 2 -V curve as the lithium plating potential of the lithium-ion battery.

4. The method for determining the lithium plating potential of a lithium-ion battery according to any one of claims 1 to 2, characterized in that, Conducting a charging test on lithium ions includes: According to the combination relationship between the charging temperature and the charging rate in the preset charging test chart, conduct charging tests on the lithium-ion battery at different charging rates at multiple charging temperatures; wherein, the charging rates at each charging temperature at least include the charging rate without lithium plating and the maximum allowable continuous charging rate; during each charging test, fully charge the lithium-ion battery to the cut-off voltage according to the charging rate.

5. The method for determining the lithium plating potential of a lithium-ion battery according to claim 4, wherein Also including: At the same charging rate, obtain the second-order differential d 2 Q / dV 2 -V curve of the charging capacity corresponding to different charging temperatures of the lithium-ion battery to determine the lithium plating potential of the lithium-ion battery at different charging temperatures; And / or, at the same charging temperature, obtain the second derivative d 2 Q / dV 2 -V curve of the charging capacity corresponding to different charging rates of the lithium-ion battery to determine the lithium plating potential of the lithium-ion battery at different charging rates.

6. The method for determining the lithium plating potential of a lithium-ion battery according to claim 4, characterized in that The charging temperature range in which the lithium-ion battery allows continuous charging includes -30°C to 55°C; the charging rate range in which the lithium-ion battery allows continuous charging includes 0.01C to 2C; During the charging test of the lithium-ion battery, the charging voltage acquisition time interval is less than or equal to 1S, and the charging voltage acquisition accuracy is less than or equal to 1mV.

7. A device for determining the lithium plating potential of a lithium-ion battery, characterized in that, Including: A data acquisition module for collecting voltage and capacity data of the lithium-ion battery during the charging test of the lithium-ion battery; wherein, during the same charging test, the charging rate is the same and the charging temperature is the same; The differential processing module performs differential processing on the voltage and the capacity data to obtain the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve; The lithium plating potential determination module is used to determine the lithium plating state of the lithium-ion battery and determine the lithium plating potential of the lithium-ion battery according to the first-order differential dQ / dV-V curve of the charging capacity of the lithium-ion battery and the second-order differential d 2 Q / dV 2 -V curve The device for determining the lithium plating potential of the lithium-ion battery is used to execute the method for determining the lithium plating potential of the lithium-ion battery according to any one of claims 1-6.

8. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for determining the lithium plating potential of the lithium-ion battery according to any one of claims 1-6.

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