WO2024131558A1 - Method and apparatus for determining potential for lithium precipitation in lithium ion battery, and electronic device - Google Patents

Abstract

Provided are a method and apparatus for determining the potential for lithium precipitation in a lithium ion battery, and an electronic device. The method comprises: carrying out a charging test on a lithium ion battery, and collecting voltage and capacity data of the lithium ion battery during the charging test (S110); performing differential processing on the voltage and capacity data, so as to obtain a first-order differential curve and second-order differential curve for charging capacity (S120); and determining the state of lithium precipitation in the lithium ion battery according to the first-order differential curve and the second-order differential curve, and determining the potential for lithium precipitation in the lithium ion battery (S130).

Description

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

This application claims priority to the Chinese patent application filed with the China Patent Office on December 23, 2022, with application number 202211667397.0. The entire contents of the above application are incorporated by reference into this application.

Technical Field

The present application relates to the field of battery technology, and in particular to a method, device and electronic equipment for determining the lithium deposition potential of a lithium-ion battery.

Background technique

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

Related technologies include the following methods for detecting lithium deposition in lithium-ion batteries: three-electrode method, voltage relaxation method, discharge voltage platform method, DC internal resistance method, coulomb efficiency method, etc. However, all of these methods are inconvenient to operate, have special test conditions, and have long test cycles, and none of them can derive the actual lithium deposition potential during the charging process of lithium-ion batteries.

SUMMARY OF THE INVENTION

The present application provides a method, device and electronic device for determining the lithium deposition potential of a lithium-ion battery to solve the above-mentioned technical problems.

The present application provides a method, device and electronic equipment for determining the lithium deposition potential of a lithium ion battery, which solves the problem of long time consumption and low accuracy in lithium deposition detection of lithium ion batteries, and can clearly and intuitively see the true lithium deposition potential of the lithium ion battery.

In a first aspect, an embodiment of the present application provides a method for determining a lithium deposition potential of a lithium ion battery, the method for determining a lithium deposition potential of a lithium ion battery comprising:

Performing a charging test on a lithium-ion battery and collecting voltage and capacity data of the lithium-ion battery during the charging test; wherein, during the same charging test process, the charging rate and the charging temperature are the same;

Differentiate the voltage and capacity data to obtain 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 charging capacity of the lithium-ion battery;

The lithium deposition state of the lithium ion battery is judged and the lithium deposition potential of the lithium ion battery is determined 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 charging capacity of the lithium ion battery.

In a second aspect, an embodiment of the present application provides a device for determining a lithium deposition potential of a lithium ion battery, the device for determining a lithium deposition potential of a lithium ion battery comprising:

The data acquisition module is configured to collect voltage and capacity data of the lithium-ion battery during a charging test of the lithium-ion battery; wherein, during the same charging test process, the charging rate is the same and the charging temperature is the same;

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

The lithium deposition potential determination module is configured to determine the lithium deposition potential of the lithium ion battery after confirming that lithium deposition occurs in 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 charging capacity of the lithium ion battery.

In a third aspect, an embodiment of the present application provides an electronic device, the electronic device comprising:

at least one processor; and

a memory communicatively connected to the at least one processor; wherein,

The memory stores a computer program that can be executed 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 deposition potential of a lithium-ion battery described in any embodiment of the present application.

Beneficial Effects

The beneficial effects of the present application are as follows: the method for determining the lithium deposition potential of a lithium ion battery provided in an embodiment of the present application, by real-time acquisition of voltage data and capacity data of the lithium ion battery during a charging test, draws a first-order differential dQ/dV-V curve and a second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery, and judges the lithium deposition state of the lithium ion battery according to the first-order differential dQ/dV-V curve and the second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery, and determines the lithium deposition potential of the lithium ion battery after confirming that lithium deposition has occurred in the lithium ion battery, thereby solving the problems of long time consumption and low accuracy in lithium deposition detection of the lithium ion battery, and at the same time being able to clearly and intuitively see the true lithium deposition potential of the lithium ion battery.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. 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 work.

FIG1 is a flow chart of a method for determining the lithium deposition potential of a lithium ion battery provided in an embodiment of the present application;

FIG2 is a preset charging test diagram of a lithium-ion battery at different charging rates and different charging temperatures provided in an embodiment of the present application;

3 is a flow chart of another method for determining the lithium deposition potential of a lithium ion battery provided in an embodiment of the present application;

FIG4 is a first-order and second-order differential curve of 1C charging capacity at 25° C. provided in an embodiment of the present application;

5 is a flow chart of another method for determining the lithium deposition potential of a lithium ion battery provided in an embodiment of the present application;

FIG6 is a first-order and second-order differential curve of 1.5C charging capacity at 25° C. provided in an embodiment of the present application;

FIG7 is a first-order and second-order differential curve of 0.1C charging capacity at -10°C provided in an embodiment of the present application;

FIG8 is a schematic structural diagram of a device for determining lithium deposition potential of a lithium-ion battery provided in an embodiment of the present application;

FIG. 9 shows a schematic diagram of the structure of an electronic device that can be used to implement an embodiment of the present application.

Embodiments of the present invention

It should be noted that the terms "first", "second", etc. in the specification and claims of the present application 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 the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

The present application embodiment provides a method for determining the lithium deposition potential of a lithium ion battery. FIG. 1 is a flow chart of a method for determining the lithium deposition potential of a lithium ion battery provided in the present application embodiment. Referring to FIG. 1 , the method for determining the lithium deposition potential of a lithium ion battery includes:

S110, 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 process, the charging rate is the same and the charging temperature is the same.

Among them, the lithium-ion battery can be a lithium iron phosphate battery, a ternary lithium battery, a lithium manganese oxide battery, etc., and the embodiment of the present application is not limited to this. The lithium-ion battery can include soft-pack, square, cylindrical or special-shaped battery cells. Specifically, the 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 embodiment of the present application is not limited to this. Among them, the voltage acquisition accuracy can be 0.1mV, and the time interval for collecting voltage data can be 10ms, 20ms, 30ms, etc., and the embodiment of the present application is not limited to this, as long as the time interval for collecting voltage data is not greater than 1s. The time interval for collecting voltage data is too large, which affects the curve drawing of voltage and capacity, and then affects the accuracy of lithium ion battery lithium precipitation potential. 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 is 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 through a capacity sensor, and the current data of the lithium-ion battery during the charging test can also be measured through a current sensor, and calculated through 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 time.

Specifically, in the same charging test process, the charging rate and charging temperature should be kept the same. In order to clearly and intuitively see the lithium plating potential of lithium-ion batteries at different charging rates and different charging temperatures, the present application embodiment produces a preset charging test diagram of lithium-ion batteries at different charging rates and different charging temperatures. Through the preset charging test diagram, the rate at which the lithium-ion battery will never plating lithium can be estimated, and the maximum charging rate allowed for the lithium-ion battery can also be designed according to the preset charging test diagram. The charging temperature and charging rate in the preset charging test diagram can be adjusted according to actual needs. For example, 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 to be 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 to be relatively high. The embodiments of the present application do not limit this. If it is required to estimate the rate at which the lithium-ion battery will absolutely not deposit lithium very accurately, it is necessary to design the charging rate of the lithium-ion battery to be relatively dense. If it is required to estimate the rate at which the lithium-ion battery will absolutely not deposit lithium with low accuracy, it is sufficient to design the density of the number of charging rates of the lithium-ion battery to be moderate. The embodiments of the present application do not limit this. FIG2 is a preset charging test diagram of a lithium-ion battery at different charging rates and different charging temperatures provided in an embodiment of the present application. Referring to FIG2 , the lithium-ion battery can be subjected to charging tests at the same charging temperature and different charging rates. For example, under the condition of keeping the ambient temperature constant at 25° C., the lithium-ion battery is subjected to charging tests at 0.1C charging rate, 0.33C charging rate, 0.5C charging rate, 1.0C charging rate, 1.5C charging rate and 2.0C charging rate, respectively, wherein the same charging temperature can be achieved by a temperature control box; the lithium-ion battery can also be subjected to charging tests at the same charging rate and different charging temperatures. For example, under the condition of keeping the charging rate constant at 0.5C, the lithium-ion battery is subjected to charging tests at ambient temperatures of -10° C., 0° C., 10° C., 25° C. and 35° C., respectively, and the embodiment of the present application does not limit this.

S120 , performing 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 d ² Q/dV ² -V curve of the charging capacity of the lithium-ion battery.

Exemplarily, a voltage-capacity curve of the lithium-ion battery can be plotted based on measured voltage and capacity data of the lithium-ion battery. Based on the plotted voltage-capacity curve of the lithium-ion battery, a slope value corresponding to each point in the curve is obtained. Combined with the voltage value V corresponding to each point, a first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery is obtained. Similarly, based on the plotted first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery, a slope value corresponding to each point in the curve is obtained. Combined with the voltage value V corresponding to each point, a second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium-ion battery is obtained. The measured voltage and capacity data of the lithium-ion battery can also be processed, and the voltage value of the nth data point is used as an example for detailed description, which is as follows: the voltage value of the nth data point is added to the fixed voltage interval to obtain the voltage value of the n+1th data point, wherein the fixed voltage interval can be any value from 1mV to 5mV, and the embodiment of the present application is not limited to this. The capacity data Q1 corresponding to the voltage value of the n+1th data point is obtained by precise search; then the fixed voltage interval is subtracted from the voltage value of the nth data point to obtain the voltage value of the n-1th data point, and the capacity data Q2 corresponding to the voltage value of the n-1th data point is obtained by precise search; the capacity data Q1 corresponding to the voltage value of the n+1th data point is subtracted from the fixed voltage interval to obtain the capacity data Q2 corresponding to the voltage value of the n-1th data point; dQ can be obtained by subtracting the capacity data Q1 corresponding to the voltage value of the n+1th data point from the capacity data Q2 corresponding to the voltage value of the n-1th data point, and dV can be obtained by adding the two fixed voltage intervals. By processing all the data in sequence, a series of dV and dQ data are obtained, and then dQ is divided by dV to obtain another data dQ/dV, and then dQ/dV is used as the ordinate and the voltage corresponding to each dQ/dV data is used as the abscissa to obtain the first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery. Similarly, the voltage value of the nth data point is added to the fixed voltage interval to obtain the voltage value of the n+1th data point, and the dQ/dV data m1 corresponding to the voltage value of the n+1th data point is obtained by precise search; then the voltage value of the nth data point is subtracted from the fixed voltage interval to obtain the voltage value of the n-1th data point, and the dQ/dV data m2 corresponding to the voltage value of the n-1th data point is obtained by precise search; the dQ/dV data m1 corresponding to the voltage value of the n+1th data point is subtracted from the fixed voltage interval to obtain the voltage value of the n-1th data point, and the dQ/dV data m2 corresponding to the voltage value of the n-1th data point is obtained by precise search; the dQ/dV data m1 corresponding to the voltage value of the n+1th data point is subtracted from the dQ/dV data m2 corresponding to the voltage value of the n-1th data point to obtain d(dQ/dV), and dV is obtained by adding the two fixed voltage intervals. By processing all the data in turn, we can get a series of d(dQ/dV) data, and then divide d(dQ/dV) by dV to get another data d2Q/dV2. Then, using d2Q/dV2 as the ordinate and the voltage corresponding to each d2Q/dV2 data as the abscissa, we can get the second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium-ion battery.

S130 , judging the lithium deposition state of the lithium ion battery and determining the lithium deposition 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 d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery.

Specifically, the first-order differential dQ/dV-V curve is easily affected by the charging rate and the charging temperature. When 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 means that the characteristic peak in the first-order differential dQ/dV-V curve of the charging capacity at this time is relatively obvious, wherein the preset charging rate and the preset temperature can be set according to actual conditions, and the lithium deposition state of the lithium-ion battery can be judged by the first-order differential dQ/dV-V curve of the charging capacity. If it is confirmed that the lithium-ion battery has lithium deposition, the lithium deposition potential of the lithium-ion battery can be determined by the first-order differential dQ/dV-V curve of the charging capacity, or the lithium deposition potential of the lithium-ion battery can be determined by the second-order differential ^d2Q / ^dV2 -V curve of the charging capacity, and the embodiment of the present application does 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 means that the characteristic peak in the first-order differential dQ/dV-V curve of the charging capacity is not obvious or there is a phenomenon of fusion of voltage characteristic peaks. It is difficult to judge the lithium deposition state of the lithium-ion battery through the first-order differential dQ/dV-V curve of the charging capacity, and it is necessary to use the second-order differential d ² Q/dV ² -V curve of the charging capacity to determine the lithium deposition state of the lithium-ion battery. If it is confirmed that lithium deposition occurs in the lithium-ion battery, the lithium deposition potential of the lithium-ion battery is determined again through the second-order differential d ² Q/dV ² -V curve of the charging capacity.

The method for determining the lithium deposition potential of a lithium ion battery provided in an embodiment of the present application collects voltage data and capacity data of the lithium ion battery in real time during a charging test, draws a first-order differential dQ/dV-V curve and a second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery, and judges the lithium deposition state of the lithium ion battery and determines the lithium deposition potential of the lithium ion battery according to the first-order differential dQ/dV-V curve and the second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery, thereby solving the problems of long time consumption and low accuracy in lithium deposition detection of the lithium ion battery, and can clearly and intuitively see the true lithium deposition potential of the lithium ion battery.

FIG3 is a flow chart of another method for determining the lithium deposition potential of a lithium ion battery provided in an embodiment of the present application. Referring to FIG3 , 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, the lithium deposition state of the lithium ion battery is judged and the lithium deposition potential of the lithium ion battery is determined 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 charging capacity of the lithium ion battery. The method for determining the lithium deposition potential of the lithium ion battery includes:

S210, 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 process, the charging rate is the same and the charging temperature is the same.

S220 , performing 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 d ² Q/dV ² -V curve of the charging capacity of the lithium-ion battery.

S230: Determine whether lithium deposition occurs in the lithium-ion battery according to a first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery.

Specifically, when a lithium-ion battery undergoes a lithium deposition reaction, a voltage platform representing lithium deposition will be added, and the voltage platform representing lithium deposition corresponds to the characteristic peak of lithium deposition. 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 deposition state of the lithium-ion battery, that is, whether lithium deposition occurs in the lithium-ion battery, can be determined by 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 lithium deposition occurs in the lithium-ion battery is described in detail, as follows:

4 is the first-order and second-order differential curves of the 1C charging capacity at 25°C provided in an embodiment of the present application. As shown in FIG4 , 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. Under normal circumstances, under the condition that lithium iron phosphate batteries do not undergo lithium deposition, there will be four voltage platforms, and thus the first-order differential dQ/dV-V curve of the charging capacity will correspond to four peaks. If lithium deposition occurs in the lithium iron phosphate battery, a new voltage platform will be added, and thus the first-order differential dQ/dV-V curve of the charging capacity will correspond to a fifth peak. As shown in Figure 4, 5 peaks can be obtained from the first-order differential dQ/dV-V curve of the 1C charging capacity of the lithium iron phosphate battery at 25°C. It can be judged that there is a lithium deposition characteristic peak in the phase change peak of the first-order differential dQ/dV-V curve of the charging capacity at 25°C and 1C charging rate, which confirms that lithium deposition occurs in the lithium iron phosphate battery.

S240 , if lithium deposition occurs in the lithium ion battery, determine the lithium deposition potential of the lithium ion battery according to the second order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery.

Specifically, as shown in FIG4 , at the fifth peak 1 in the first-order differential dQ/dV-V curve of the 1C charging capacity at 25° C., the corresponding lithium deposition characteristic peak maximum point of the second-order differential d ² Q/dV ² -V curve of the 1C charging capacity at 25° C. of the lithium iron phosphate battery is found, and the voltage value corresponding to the lithium deposition characteristic peak maximum point is the lithium deposition potential of the lithium iron phosphate battery.

The method for determining the lithium deposition potential of a lithium ion battery provided in an embodiment of the present application determines whether lithium deposition occurs in the lithium ion battery according to a first-order differential dQ/dV-V curve of the charging capacity 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. If lithium deposition occurs in the lithium ion battery, the lithium deposition potential of the lithium ion battery is determined according to a second-order differential charging capacity ^d2Q / ^dV2 -V curve of the lithium ion battery. That is, when the characteristic peak of the first-order curve is obvious, determining whether lithium deposition occurs in the lithium ion battery according to the first-order differential dQ/dV-V curve of the charging capacity not only can clearly and intuitively see the true lithium deposition potential of the lithium ion battery, but also is convenient, fast and highly accurate.

FIG5 is a flow chart of another method for determining the lithium deposition potential of a lithium ion battery provided by an embodiment of the present application. As shown in FIG5 , 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, the lithium deposition state of the lithium ion battery is judged and the lithium deposition potential of the lithium ion battery is determined 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 charging capacity of the lithium ion battery. The method for determining the lithium deposition potential of the lithium ion battery includes:

S310, 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 process, the charging rate is the same and the charging temperature is the same.

S320 , performing 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 d ² Q/dV ² -V curve of the charging capacity of the lithium-ion battery.

S330 , judging whether lithium deposition 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 and in combination with the second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery.

Specifically, 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 means that the characteristic peak in the first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery is not obvious or the characteristic peak in the first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery will be fused. It is difficult to judge the lithium deposition state of the lithium-ion battery by the first-order differential dQ/dV-V curve of the charging capacity. At this time, it is necessary to combine the second-order differential ^d2Q / ^dV2 -V curve of the charging capacity of the lithium-ion battery to judge whether lithium deposition occurs in the lithium-ion battery. Exemplarily, under the condition that the charging rate is greater than the preset charging rate, a lithium iron phosphate battery with a charging temperature of 25°C and a charging rate of 1.5C is taken as an example to explain in detail whether lithium deposition occurs in the lithium-ion battery, and the specific description is as follows:

FIG6 is a first-order and second-order differential curve of a 1.5C charging capacity at 25°C provided by an embodiment of the present application. As shown in FIG6 , the dotted line is a first-order differential dQ/dV-V curve of a 1.5C charging capacity of a lithium iron phosphate battery at 25°C, and the solid line is a second-order differential d ² Q/dV ² -V curve of a 1.5C charging capacity of a lithium iron phosphate battery at 25°C. Under normal circumstances, under the condition that lithium iron phosphate batteries do not undergo lithium deposition, there will be four voltage platforms, and thus the first-order differential curve of the charging capacity will correspond 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 at 25°C are fused. As shown in FIG6 , 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 ² Q/dV ² -V curve is used to judge whether lithium deposition occurs in the lithium iron phosphate battery. For every characteristic peak in the first-order differential dQ/dV-V curve, a maximum point will appear in the second-order differential d ² Q/dV ² -V curve. When five maximum points appear in the second-order differential d ² Q/dV ² -V curve, it can be judged that lithium deposition occurs in the lithium iron phosphate battery under the conditions of 25°C and 1.5C charging rate.

When the charging rate is too high, the fusion of the characteristic peaks in the first-order differential dQ/dV-V curve of the charging capacity is more obvious, which affects the number of peaks in the second-order differential ^d2Q / ^dV2 -V curve. At this time, it is not suitable to combine the first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery with the second-order differential ^d2Q / ^dV2 -V curve of the charging capacity of the lithium-ion battery to determine whether lithium deposition occurs in the lithium-ion battery by the number of characteristic peaks. Under different charging temperatures, the method of combining the first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery with the second-order differential ^d2Q / ^dV2 -V curve of the charging capacity of the lithium-ion battery is suitable for different charging rate ranges. For example, referring to FIG6, under the condition of a charging temperature of 25°C and a charging rate of less than 1.5C, the method of combining the first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery with the second-order differential ^d2Q / ^dV2 -V curve of the charging capacity of the lithium-ion battery can be used to determine whether lithium deposition occurs in 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 a 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 condition that the charging temperature is lower than the preset temperature, a lithium iron phosphate battery with a charging temperature of -10°C and a charging rate of 0.1C is used as an example to explain in detail whether lithium plating occurs in the lithium-ion battery. The specific description is as follows:

FIG7 is a first-order and second-order differential curves of the 0.1C charging capacity at -10°C provided by an embodiment of the present application. As shown in FIG7 , the dotted line is the first-order differential dQ/dV-V curve of the 0.1C charging capacity of the lithium iron phosphate battery at -10°C, and the solid line is the second-order differential d ² Q/dV ² -V curve of the 0.1C charging capacity of the lithium iron phosphate battery at -10°C. Under normal circumstances, under the condition that lithium iron phosphate batteries do not undergo lithium precipitation, there will be four voltage platforms, and thus the first-order differential curve of the charging capacity will correspond to four peaks. However, because the charging temperature at this time is lower than the preset temperature, the characteristic peaks in the first-order differential dQ/dV-V curve of the charging capacity at -10°C are fused. As shown in FIG7 , the characteristic peaks in the first-order differential dQ/dV-V curve of the 0.1C charging capacity of the lithium iron phosphate battery at -10°C are not obvious. At this time, combined with the second-order differential d ² Q/dV ² -V curve is used to judge whether lithium deposition occurs in the lithium iron phosphate battery. For every characteristic peak in the first-order differential dQ/dV-V curve, a maximum point will appear in the second-order differential d ² Q/dV ² -V curve. When five maximum points appear in the second-order differential d ² Q/dV ² -V curve, it can be judged that lithium deposition occurs in the lithium iron phosphate battery under the conditions of -10℃ and 0.1C charging rate.

When the charging temperature is too low, referring to FIG6 , at this time, the fusion of the characteristic peaks in the first-order differential dQ/dV-V curve of the charging capacity is more obvious, 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 suitable to combine 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 lithium-ion battery to judge whether lithium deposition occurs in the lithium-ion battery by the number of characteristic peaks. At different charging temperatures, the method of determining whether lithium deposition occurs in a lithium-ion battery by combining the first-order differential dQ/dV-V curve of the charging capacity with the second-order differential ^d2Q / ^dV2 -V curve of the charging capacity of the lithium-ion battery is applicable to different charging rate ranges. Exemplarily, under the conditions that the charging temperature is -10°C and the charging rate is less than 0.1C, the method of determining whether lithium deposition 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 ^d2Q / ^dV2 -V curve of the charging capacity of the lithium-ion battery is applicable. Under the conditions that the charging temperature is -10°C and the charging rate is greater than 0.1C, it is not applicable to determine whether lithium deposition 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 ^d2Q / ^dV2 -V curve of the charging capacity of the lithium-ion battery.

S340: If lithium deposition occurs in the lithium-ion battery, determine the lithium deposition potential of the lithium-ion battery according to a second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium-ion battery.

Specifically, as shown in Figures 6 and 7, the voltage value corresponding to the maximum point of the second-order differential ^d2Q / ^dV2 -V curve of the charging capacity of the lithium iron phosphate battery is the lithium deposition potential of the lithium iron phosphate battery. Exemplarily, the voltage value corresponding to the fifth characteristic peak 2 shown in Figure 6 is the lithium deposition potential of the lithium iron phosphate battery, and the voltage value corresponding to the fifth characteristic peak 3 shown in Figure 7 is the lithium deposition potential of the lithium iron phosphate battery.

The method for determining the lithium deposition potential of a lithium ion battery provided in an embodiment of the present application determines whether lithium deposition occurs in the lithium ion battery according to a first-order differential dQ/dV-V curve of the charging capacity of the lithium ion battery and in combination with a second-order differential 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 less than a preset temperature. If lithium deposition occurs in the lithium ion battery, the lithium deposition potential of the lithium ion battery is determined according to the second-order differential d ² Q/dV ² -V curve of the lithium ion battery. That is, when the characteristic peak of the first-order curve is not obvious or merged, determining whether lithium deposition occurs in the lithium ion battery according to the first-order differential dQ/dV-V curve of the charging capacity and in combination with the second-order differential d ² Q/dV ² -V curve of the charging capacity not only can clearly and intuitively see the true lithium deposition potential of the lithium ion battery, but also is convenient, fast and highly accurate.

Optionally, referring to FIG. 4 , FIG. 6 and FIG. 7 , determining the lithium deposition potential of the lithium ion battery according to the second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery includes:

Determine the voltage corresponding to the maximum point of the characteristic peak of lithium deposition in the second-order differential d ² Q/dV ² -V curve of the charging capacity;

The voltage corresponding to the maximum point of the lithium deposition characteristic peak in the second-order differential d ² Q/dV ² -V curve of the charging capacity is determined as the lithium deposition potential of the lithium ion battery.

Exemplarily, as shown in FIG4, at the fifth peak in the first-order differential dQ/dV-V curve of 1C charging capacity at 25°C, the corresponding lithium precipitation characteristic peak maximum point of the second-order differential ^d2Q / ^dV2 -V curve of 1C charging capacity at 25°C is found, and the voltage value corresponding to the maximum point of the lithium precipitation characteristic peak is the lithium precipitation potential of the lithium iron phosphate battery; as shown in FIG6 and FIG7, the voltage value corresponding to the maximum point of the lithium precipitation characteristic peak of the second-order differential ^d2Q / ^dV2 -V curve of the charging capacity of the lithium iron phosphate battery is the lithium precipitation potential of the lithium iron phosphate battery. Since the peak in the second-order differential ^d2Q / ^dV2 -V curve is high in sharpness, it is easy to determine the location of the peak point, so the voltage corresponding to the maximum point of the lithium precipitation characteristic peak in the second-order differential ^d2Q / ^dV2 -V curve of the charging capacity is determined as the lithium precipitation potential of the lithium ion battery, which can further clearly and intuitively see the real lithium precipitation potential of the lithium ion battery and improve accuracy.

Optionally, as shown in FIG2 , a charging test is performed on lithium ions, and a method for determining the lithium deposition potential of a lithium ion battery includes:

According to the combination relationship between the charging temperature and the charging rate in the preset charging test diagram, the lithium-ion battery is charged at different charging rates at multiple charging temperatures; wherein the charging rate at each charging temperature at least includes the charging rate without lithium deposition and the maximum allowed continuous charging rate; during each charging test, the lithium-ion battery is fully charged to the cut-off voltage according to the charging rate.

Exemplarily, under the condition of keeping the ambient temperature constant at 25°C, the lithium-ion battery is charged at 0.1C charging rate, 0.33C charging rate, 0.5C charging rate, 1.0C charging rate, 1.5C charging rate and 2.0C charging rate, respectively, wherein the same charging temperature can be achieved by a temperature control box; the lithium-ion battery can also be charged at the same charging rate and different charging temperatures. Exemplarily, under the condition of keeping the charging rate constant at 0.5C, the lithium-ion battery is charged at an ambient temperature of -10°C, 0°C, 10°C, 25°C, and 35°C, respectively. The embodiment of the present application does not limit this. Specifically, the charging rate at each charging temperature includes at least the charging rate without lithium precipitation and the maximum continuous charging rate allowed. It can be understood that, by presetting the charging test diagram, the rate at which the lithium-ion battery absolutely does not precipitate lithium can be estimated, and the maximum charging rate allowed for the lithium-ion battery can also be designed according to the preset charging test diagram. During each charging test, the lithium-ion battery is fully charged to a cut-off voltage according to the charging rate. For example, the cut-off voltage of the lithium iron phosphate battery is 3.55V-3.65V, and the cut-off voltage of the ternary lithium battery is 4.2V-4.35V.

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

Under the same charging rate, 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 is obtained to determine the lithium plating potential of the lithium-ion battery at different charging temperatures; thereby, it is convenient to determine the appropriate charging temperature at each charging rate and the appropriate charging stop potential at different charging temperatures.

And/or, at the same charging temperature, the second-order differential d ² Q/dV ² -V curve of the charging capacity corresponding to different charging rates of the lithium ion battery is obtained to determine the lithium deposition potential of the lithium ion battery at different charging rates, so as to facilitate the determination of the appropriate charging rate at each charging temperature and the appropriate charging stop potential at different charging rates.

Optionally, the charging temperature range of the lithium-ion battery that allows continuous charging includes -30°C to 55°C; the charging rate range of the lithium-ion battery that allows continuous charging includes 0.01C to 2C;

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

Specifically, if the time interval for collecting voltage data is too long, it will affect the drawing of voltage and capacity curves, and thus affect the accuracy of lithium ion battery lithium deposition potential. If the charging voltage collection time interval is less than or equal to 1S and the charging voltage collection accuracy is less than or equal to 1mV, the accuracy of lithium ion battery lithium deposition potential can be guaranteed.

FIG8 is a schematic diagram of the structure of a device for determining the lithium deposition potential of a lithium ion battery provided in an embodiment of the present application. As shown in FIG8 , the device 500 for determining the lithium deposition potential of a lithium ion battery includes:

The data acquisition module 510 is used to collect the voltage and capacity data of the lithium-ion battery during the charging test of the lithium-ion battery; wherein, in the same charging test process, the charging rate is the same and the charging temperature is the same;

A differential processing module 520 performs differential processing on the voltage and the capacity data to obtain a first-order differential dQ/dV-V curve of the charging capacity and a second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium-ion battery;

The lithium deposition potential determination module 530 is used to judge the lithium deposition state of the lithium ion battery according to the first-order differential dQ/dV-V curve and the second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery, and determine the lithium deposition potential of the lithium ion battery after confirming that lithium deposition occurs in the lithium ion battery.

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 deposition state of the lithium-ion battery is judged 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 charging capacity of the lithium-ion battery, and the lithium deposition potential of the lithium-ion battery is determined after confirming that lithium deposition occurs in the lithium-ion battery. The lithium deposition potential determination module 530 includes:

First-order judgment unit: used to judge whether lithium deposition 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;

Lithium deposition determination unit: used to determine the lithium deposition potential of the lithium ion battery according to the second-order differential d ² Q/dV ² -V curve of the lithium ion battery if lithium deposition occurs in the lithium ion battery.

Further, 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, the lithium deposition state of the lithium-ion battery is judged 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 charging capacity of the lithium-ion battery, and the lithium deposition potential of the lithium-ion battery is determined after confirming that lithium deposition occurs in the lithium-ion battery. The lithium deposition potential determination module 530 includes:

Combined judgment unit: judging whether lithium deposition 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 and in combination with the second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium-ion battery;

Lithium deposition determination unit: if lithium deposition occurs in the lithium-ion battery, the lithium deposition potential of the lithium-ion battery is determined according to the second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium-ion battery.

Furthermore, the first-order judgment unit is specifically used for:

Determine whether there is a lithium precipitation 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 deposition occurs in the lithium-ion battery; wherein, when a lithium deposition reaction occurs in a lithium-ion battery, a voltage platform representing lithium deposition will be added, and the voltage platform representing lithium deposition corresponds to a characteristic peak of lithium deposition.

Furthermore, the lithium precipitation determination unit is specifically used for:

Determine the voltage corresponding to the maximum point of the characteristic peak of lithium deposition in the second-order differential d ² Q/dV ² -V curve of the charging capacity;

The voltage corresponding to the maximum point of the lithium deposition characteristic peak in the second-order differential d ² Q/dV ² -V curve of the charging capacity is determined as the initial lithium deposition potential of the lithium ion battery.

Furthermore, the combined test unit is specifically used for:

According to the combination relationship between the charging temperature and the charging rate in the preset charging test diagram, the lithium-ion battery is charged at different charging rates at various charging temperatures; wherein the charging rate at each charging temperature at least includes the charging rate at which it is estimated that there will be absolutely no lithium deposition and the maximum continuous charging rate allowed; during each charging test, the lithium-ion battery is fully charged to the cut-off voltage according to the test charging rate.

Furthermore, the combined test unit also includes:

Under 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 deposition potential of the lithium-ion battery at different temperatures;

And/or, at the same charging temperature, the second-order differential curve of the charging capacity corresponding to different charging rates of the lithium battery is obtained to determine the lithium deposition potential of the lithium-ion battery at different charging rates.

Furthermore, the temperature range for continuous charging of lithium-ion batteries includes -30°C to 55°C; the charging rate range for continuous charging of lithium-ion batteries includes 0.01C to 2C;

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

Further, types of lithium-ion batteries include lithium iron phosphate batteries, ternary lithium batteries, and lithium manganese oxide batteries;

Lithium-ion batteries include soft-pack, square, cylindrical or special-shaped battery cells.

The device for determining the lithium deposition potential of a lithium-ion battery provided in the embodiment of the present application can execute the method for determining the lithium deposition potential of a lithium-ion battery provided in any embodiment of the present application, and has the functional modules and beneficial effects corresponding to the execution method.

Fig. 9 shows a schematic diagram of the structure of an electronic device that can be used to implement an embodiment of the present application. 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 merely examples and are not intended to limit the implementation of the present application described and/or required herein.

As shown in FIG9 , the electronic device 10 includes at least one processor 11, and a memory connected to the at least one processor 11 in communication, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and 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 to 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.

A number of 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 disk, an optical disk, 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 through a computer network such as the Internet and/or various telecommunication networks.

The processor 11 may be a variety of general and/or special 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, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The processor 11 performs the various methods and processes described above, such as a method for determining the lithium potential of a lithium-ion battery.

In some embodiments, the method for determining the lithium potential of a lithium-ion battery may be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, which may be non-volatile or volatile, such as a storage unit 18. In some embodiments, part or all of the computer program may be loaded and/or installed on 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 potential of a lithium-ion battery described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to perform a method for determining the lithium potential of a lithium-ion battery by any other appropriate means (e.g., by means of firmware).

Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and/or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and/or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

The computer program for implementing the method for determining the lithium potential of lithium ion batteries of the present application 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 device, so that when the computer program is executed by the processor, the functions/operations specified in the flow chart and/or block diagram are implemented. The computer program can be executed entirely on the machine, partially on the machine, partially on the machine as a stand-alone software package and partially on a remote machine, or entirely on a remote machine or server.

In the context of the present application, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, device, or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, 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 disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

To provide interaction with a user, the systems and techniques described herein may 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 trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

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

A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

Claims (10)

1. A method for determining the lithium deposition potential of a lithium ion battery, comprising:

   Performing a charging test on a lithium-ion battery and collecting voltage and capacity data of the lithium-ion battery during the charging test; wherein, during the same charging test process, the charging rate and the charging temperature are the same;

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

   The lithium deposition state of the lithium ion battery is judged and the lithium deposition potential of the lithium ion battery is determined 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 charging capacity of the lithium ion battery.
2. The method for determining the lithium deposition potential of a lithium ion battery according to claim 1, wherein 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 deposition state of the lithium ion battery and determining the lithium deposition 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, comprises:

   Determining whether lithium deposition occurs in the lithium-ion battery according to a first-order differential dQ/dV-V curve of the charging capacity of the lithium-ion battery;

   If lithium deposition occurs in the lithium ion battery, the lithium deposition potential of the lithium ion battery is determined according to a second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery.
3. The method for determining the lithium deposition potential of a lithium ion battery according to claim 1, wherein:

   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, judging the lithium deposition state of the lithium ion battery and determining the lithium deposition 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 d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery, comprising:

   Determining whether lithium deposition occurs in the lithium ion battery according to a first-order differential dQ/dV-V curve of the charging capacity of the lithium ion battery and in combination with a second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery;

   If lithium deposition occurs in the lithium ion battery, the lithium deposition potential of the lithium ion battery is determined according to a second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery.
4. The method for determining the lithium deposition potential of a lithium ion battery according to claim 2, wherein judging whether lithium deposition occurs in the lithium ion battery according to a first-order differential dQ/dV-V curve of the charging capacity of the lithium ion battery comprises:

   Determining whether there is a lithium precipitation 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 deposition occurs in the lithium ion battery; wherein, when the lithium ion battery undergoes a lithium deposition reaction, a voltage platform representing lithium deposition will be added, and the voltage platform representing lithium deposition corresponds to the lithium deposition characteristic peak.
5. The method for determining the lithium deposition potential of a lithium ion battery according to claim 2 or 3, wherein determining the lithium deposition potential of the lithium ion battery according to a second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery comprises:

   Determining the voltage corresponding to the maximum point of the lithium deposition characteristic peak in the second-order differential d ² Q/dV ² -V curve of the charging capacity;

   The voltage corresponding to the maximum point of the lithium deposition characteristic peak in the second-order differential d ² Q/dV ² -V curve of the charging capacity is determined as the lithium deposition potential of the lithium ion battery.
6. The method for determining the lithium deposition potential of a lithium ion battery according to any one of claims 1 to 4, wherein the charging test of lithium ions comprises:

   According to the combination relationship between the charging temperature and the charging rate in the preset charging test diagram, the lithium-ion battery is charged at different charging rates at multiple charging temperatures; wherein the charging rate at each charging temperature at least includes the charging rate without lithium deposition and the maximum allowed continuous charging rate; during each charging test, the lithium-ion battery is fully charged to the cut-off voltage according to the charging rate.
7. The method for determining the lithium deposition potential of a lithium ion battery according to claim 6, further comprising:

   Under the same charging rate, obtaining 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 deposition potential of the lithium ion battery at different charging temperatures;

   And/or, at the same charging temperature, obtaining the second-order differential d ² Q/dV ² -V curve of the charging capacity corresponding to different charging rates of the lithium ion battery, so as to determine the lithium deposition potential of the lithium ion battery at different charging rates.
8. The method for determining the lithium deposition potential of a lithium-ion battery according to claim 6, wherein the charging temperature range for continuous charging of the lithium-ion battery includes -30°C to 55°C; the charging rate range for continuous charging of the lithium-ion battery includes 0.01C to 2C;

   During the lithium-ion battery charging test, the charging voltage collection time interval is less than or equal to 1S, and the charging voltage collection accuracy is less than or equal to 1mV.
9. A device for determining lithium deposition potential of a lithium-ion battery, comprising:

   The data acquisition module is configured to collect voltage and capacity data of the lithium-ion battery during a charging test of the lithium-ion battery; wherein, during the same charging test process, the charging rate is the same and the charging temperature is the same;

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

   The lithium deposition potential determination module is configured to judge the lithium deposition state of the lithium ion battery and determine the lithium deposition potential of the lithium ion battery according to the first-order differential dQ/dV-V curve and the second-order differential d ² Q/dV ² -V curve of the charging capacity of the lithium ion battery.
10. An electronic device, comprising:

    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 deposition potential of a lithium-ion battery according to any one of claims 1 to 8.