Safe charging control method, device and equipment of lithium battery and storage medium

Abstract

The invention provides a safe charging control method and device of a lithium battery, equipment and a storage medium, and relates to the technical field of lithium batteries. The method comprises the following steps: carrying out impedance test on a lithium battery to obtain a target voltage interference signal indicating that a battery cathode responds and a battery anode does not respond; and then charging the lithium battery, and carrying out capacitance test on the cathode of the lithium battery in real time according to the target voltage interference signal to obtain the cathode capacitance value of the lithium battery in the current charging state. And when it is determined that the negative capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets a preset condition, determining an electric quantity value range according to the electric quantity of the lithium battery corresponding to the current charging state. And in the subsequent charging process of the lithium battery, the electric quantity of the lithium battery is controlled to be within the electric quantity value range. According to the invention, safe charging of the lithium battery can be realized.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to a safe charging control method, apparatus, device and storage medium for lithium batteries. Background Technology

[0002] Lithium-ion batteries are widely used in consumer electronics, electric vehicles, and energy storage systems due to their high energy density and long lifespan. However, lithium plating during charging not only leads to capacity decay but can also cause internal short circuits due to direct contact between the positive and negative electrodes. Therefore, it is necessary to determine the safe charging range for lithium-ion batteries in advance to avoid lithium plating.

[0003] In existing technologies, a reference electrode is added to the lithium battery using a three-electrode technique. During the charging process, the potential range of the negative electrode is determined based on the potential of the reference electrode and a "safe potential range." The safe potential range is defined as follows: the difference between the potential of the negative electrode and the potential of the reference electrode remains greater than 0 mV. Furthermore, the charging of the lithium battery is controlled based on this negative electrode potential range.

[0004] Because current technology for controlling the charging of lithium batteries relies on a reference electrode added to the lithium battery, and the instability of the reference electrode can make it impossible to safely charge the lithium battery. Summary of the Invention

[0005] This application provides a safe charging control method, apparatus, device, and storage medium for lithium batteries, to solve the technical problem that the prior art cannot safely charge batteries.

[0006] In a first aspect, this application provides a safe charging control method for a lithium battery, comprising:

[0007] Impedance testing is performed on the lithium battery to obtain the target voltage interference signal; wherein, the target voltage interference signal characterizes the voltage interference signal when the negative electrode of the battery responds and the positive electrode of the battery does not respond;

[0008] During the charging process of the lithium battery, the capacitance of the negative electrode of the lithium battery is tested in real time according to the target voltage interference signal to obtain the capacitance value of the negative electrode of the lithium battery in the current charging state. When it is determined that the capacitance value of the negative electrode of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions, the range of the charge value is determined according to the charge of the lithium battery corresponding to the current charging state. The maximum value in the range of the charge value is the charge of the lithium battery corresponding to the current charging state. The charging state represents the ratio of the charge stored in the lithium battery to the maximum capacity of the lithium battery.

[0009] During the subsequent charging process of the lithium battery, the power level of the lithium battery is controlled to remain within the specified power level range.

[0010] In one possible design, impedance testing of the lithium battery is performed to obtain the target voltage interference signal, including:

[0011] A preset voltage interference signal is applied to the lithium battery to perform an impedance test on the lithium battery, thereby obtaining the positive electrode impedance response curve and the negative electrode impedance response curve of the lithium battery; wherein, the positive electrode impedance response curve represents the change of the positive electrode impedance value as the frequency of the preset voltage interference signal changes, and the negative electrode impedance response curve represents the change of the negative electrode impedance value as the frequency of the preset voltage interference signal changes.

[0012] The target voltage interference signal is determined from the preset voltage interference signal based on the positive impedance response curve and the negative impedance response curve.

[0013] In one possible design, the target voltage interference signal is determined from the preset voltage interference signal based on the positive impedance response curve and the negative impedance response curve, including:

[0014] Determine the first peak value in the positive electrode impedance response curve and the second peak value in the negative electrode impedance response curve; wherein the first peak value indicates the impedance response of the battery positive electrode and the second peak value indicates the impedance response of the battery negative electrode, and the impedance response characterizes the change in the rate of change of the impedance value;

[0015] Based on the frequency of the preset voltage interference signal corresponding to the first peak and the frequency of the preset voltage interference signal corresponding to the second peak, a target frequency indicating that the negative electrode of the battery responds and the positive electrode of the battery does not respond is determined.

[0016] The portion of the preset voltage interference signal at the target frequency is identified as the target voltage interference signal.

[0017] In one possible design, based on the target voltage interference signal, the capacitance of the negative electrode of the lithium battery is tested in real time to obtain the capacitance value of the negative electrode of the lithium battery under the current charging state, including:

[0018] The target voltage interference signal is applied to the negative electrode of the lithium battery to obtain the negative electrode capacitance response curve of the lithium battery; wherein, the negative electrode capacitance response curve characterizes the change of the negative electrode capacitance value of the lithium battery with the change of the state of charge.

[0019] Based on the negative electrode capacitor response curve, the negative electrode capacitor value of the lithium battery under the current charging state is obtained.

[0020] In one possible design, when it is determined that the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets a preset condition, the range of the charge value is determined based on the lithium battery charge corresponding to the current charging state, including:

[0021] If the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions, then the lithium battery capacity corresponding to the current charging state is determined as the target capacity of the lithium battery.

[0022] The range of power values ​​is determined based on the lithium battery power that is less than or equal to the target power value.

[0023] In one possible design, before determining the lithium battery capacity corresponding to the current charging state as the target capacity of the lithium battery if the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets a preset condition, the following further step is taken:

[0024] Based on the negative electrode capacitance value of the lithium battery in the current charging state and the negative electrode capacitance value of the lithium battery in the next charging state, calculate the capacitance change rate between adjacent charging states.

[0025] If the capacitance change rate is greater than a preset threshold, then the negative electrode capacitance value of the lithium battery in the next charging state is determined to meet the preset conditions; otherwise, the negative electrode capacitance value of the lithium battery in the next charging state is determined to not meet the preset conditions.

[0026] In one possible design, the method further includes:

[0027] The lithium battery is charged using different charging rates;

[0028] Impedance testing is performed on the lithium battery, and capacitance testing is performed on the negative electrode of the lithium battery to determine the range of charge values ​​under different charging rates.

[0029] A battery charging curve is generated based on the maximum value of the power range under different charging rates; wherein, the battery charging curve represents the change of charging rate as the maximum value of the power range changes;

[0030] During subsequent charging of the lithium battery, the lithium battery charge is controlled to be within a range lower than the charge indicated by the battery charging curve.

[0031] Secondly, this application provides a safe charging control device for a lithium battery, comprising:

[0032] The processing module is used to perform impedance testing on the lithium battery to obtain the target voltage interference signal; wherein, the target voltage interference signal characterizes the voltage interference signal when the negative electrode of the battery responds and the positive electrode of the battery does not respond.

[0033] The processing module is also used to perform a capacitance test on the negative electrode of the lithium battery in real time according to the target voltage interference signal during the charging process of the lithium battery, so as to obtain the capacitance value of the negative electrode of the lithium battery under the current charging state.

[0034] The determining module is used to determine the range of power values ​​based on the power of the lithium battery corresponding to the current charging state when the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions; wherein, the maximum value in the range of power values ​​is the power of the lithium battery corresponding to the current charging state, and the charging state represents the ratio of the power stored in the lithium battery to the maximum capacity of the lithium battery.

[0035] The control module is used to control the power level of the lithium battery during subsequent charging of the lithium battery, ensuring that the power level remains within the specified range.

[0036] In one possible design, the processing module is further configured to apply a preset voltage interference signal to the lithium battery to perform an impedance test on the lithium battery and obtain the positive electrode impedance response curve and the negative electrode impedance response curve of the lithium battery; wherein, the positive electrode impedance response curve represents the change of the positive electrode impedance value as the frequency of the preset voltage interference signal changes, and the negative electrode impedance response curve represents the change of the negative electrode impedance value as the frequency of the preset voltage interference signal changes.

[0037] The determining module is further configured to determine the target voltage interference signal from the preset voltage interference signal based on the positive impedance response curve and the negative impedance response curve.

[0038] In one possible design, the determining module is further configured to:

[0039] Determine the first peak value in the positive electrode impedance response curve and the second peak value in the negative electrode impedance response curve; wherein the first peak value indicates the impedance response of the battery positive electrode and the second peak value indicates the impedance response of the battery negative electrode, and the impedance response characterizes the change in the rate of change of the impedance value;

[0040] Based on the frequency of the preset voltage interference signal corresponding to the first peak and the frequency of the preset voltage interference signal corresponding to the second peak, a target frequency indicating that the negative electrode of the battery responds and the positive electrode of the battery does not respond is determined.

[0041] The portion of the preset voltage interference signal at the target frequency is identified as the target voltage interference signal.

[0042] In one possible design, the processing module is further configured to apply the target voltage interference signal to the negative electrode of the lithium battery to obtain the negative electrode capacitance response curve of the lithium battery; wherein the negative electrode capacitance response curve characterizes the change in the negative electrode capacitance value of the lithium battery with changes in the state of charge.

[0043] The processing module further includes an acquisition module, used to acquire the negative electrode capacitance value of the lithium battery under the current charging state based on the negative electrode capacitance response curve.

[0044] In one possible design, the determining module is further configured to:

[0045] If the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions, then the lithium battery capacity corresponding to the current charging state is determined as the target capacity of the lithium battery.

[0046] The range of power values ​​is determined based on the lithium battery power that is less than or equal to the target power value.

[0047] In one possible design, the lithium battery safety charging control device further includes: a calculation module for calculating the capacitance change rate between adjacent charging states based on the lithium battery negative electrode capacitance value in the current charging state and the lithium battery negative electrode capacitance value in the next charging state.

[0048] The determining module is further configured to determine that the negative electrode capacitance value of the lithium battery in the next charging state meets the preset conditions if the capacitance change rate is greater than a preset threshold; otherwise, determine that the negative electrode capacitance value of the lithium battery in the next charging state does not meet the preset conditions.

[0049] In one possible design, the processing module is further configured to:

[0050] The lithium battery is charged using different charging rates;

[0051] Impedance testing is performed on the lithium battery, and capacitance testing is performed on the negative electrode of the lithium battery to determine the range of charge values ​​under different charging rates.

[0052] A battery charging curve is generated based on the maximum value of the power range under different charging rates; wherein, the battery charging curve represents the change of charging rate as the maximum value of the power range changes;

[0053] The control module is also used to control the lithium battery charge during subsequent charging of the lithium battery to be within a range that is less than the charge indicated by the battery charging curve.

[0054] Thirdly, this application provides an electronic device comprising: at least one processor and a memory; the memory storing computer-executable instructions; the at least one processor executing the computer-executable instructions stored in the memory, causing the at least one processor to perform the method described in the first aspect above and various possible designs.

[0055] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the methods described in the first aspect above and various possible designs.

[0056] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the method described in the first aspect and various possible designs of the first aspect.

[0057] The lithium battery safe charging control method, apparatus, device, and storage medium provided in this application perform impedance testing on the lithium battery to obtain a target voltage interference signal. This target voltage interference signal characterizes a voltage interference signal that responds at the negative electrode but not at the positive electrode. During the charging process, based on the target voltage interference signal, the capacitance of the negative electrode of the lithium battery is tested in real time to obtain the negative electrode capacitance value of the lithium battery in the current charging state. When it is determined that the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets preset conditions, a range of charge values ​​is determined based on the lithium battery charge corresponding to the current charging state. The maximum value within the charge value range represents the lithium battery charge corresponding to the current charging state, and the charging state characterizes the ratio of the stored charge to the maximum capacity of the lithium battery. During subsequent charging of the lithium battery, the charge of the lithium battery is controlled to remain within the charge value range. By performing impedance and capacitance testing on the lithium battery, the state of the negative electrode of the lithium battery can be monitored in real time, and changes in the negative electrode capacitance value can reflect the health and charging state of the negative electrode, thus providing more accurate and dynamic battery state information. Meanwhile, this application does not rely on additional hardware, is more adaptable, and can be more easily integrated into the battery management system to achieve safe charging of lithium batteries. Attached Figure Description

[0058] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0059] Figure 1 A schematic flowchart illustrating the safe charging control method for lithium batteries provided in this application embodiment;

[0060] Figure 2 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 1 ;

[0061] Figure 3 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 2 ;

[0062] Figure 4 The equivalent circuit diagram of the negative electrode of a lithium battery for the safe charging control method of a lithium battery provided in the embodiments of this application;

[0063] Figure 5 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 3 ;

[0064] Figure 6 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 4 ;

[0065] Figure 7 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 5 ;

[0066] Figure 8 This is a schematic diagram of the structure of a lithium battery safety charging control device provided in an embodiment of this application;

[0067] Figure 9 This is a hardware structure diagram of the electronic device provided in the embodiments of this application.

[0068] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0069] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0070] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention 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 where appropriate so that embodiments of the invention described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0071] In this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0072] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of the relevant data must comply with relevant laws, regulations and standards, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0073] First, the terms used in this application will be explained.

[0074] Lithium plating: When a battery is overcharged or charged at a high current density, lithium ions may be reduced to metallic lithium on the surface of the negative electrode, forming lithium dendrites.

[0075] During the charging process of lithium batteries, especially under overcharging or high current density charging conditions, lithium ions may be reduced to metallic lithium on the surface of the negative electrode. When lithium is deposited in metallic form, it means that this portion of lithium no longer participates in the normal charge-discharge cycle of the lithium battery, resulting in a reduction in available lithium ions and a decrease in the capacity of the lithium battery.

[0076] In addition, lithium metal deposited on the surface of the negative electrode may form lithium dendrites, which may pierce the separator of the lithium battery, causing direct contact between the positive and negative electrodes, which in turn can cause an internal short circuit, leading to overheating of the lithium battery, and even potentially causing safety accidents such as fires.

[0077] To avoid lithium plating, the safe charging range of lithium batteries must be determined.

[0078] In existing technologies, a three-electrode technique is used to add a reference electrode to the lithium battery. During the charging process of the lithium battery, the potential range of the negative electrode is determined based on the potential of the reference electrode and a "safe potential range." The safe potential range is defined as follows: the difference between the potential of the negative electrode and the potential of the reference electrode remains greater than 0 mV. Based on this negative potential range, the power supply is controlled to charge the lithium battery.

[0079] However, the potential of the reference electrode can change due to variations in temperature or electrochemical reactions within the lithium battery. Furthermore, the reference electrode has a limited lifespan, making continuous monitoring throughout the entire lifespan of the lithium battery impossible.

[0080] Existing technologies do not take into account the potential changes of the reference electrode or the lifespan of the reference electrode, resulting in inaccurate ranges of the obtained negative electrode potential, which in turn makes it impossible to safely charge lithium batteries.

[0081] To address the aforementioned technical problems, the inventors considered that the instability of the reference electrode could lead to inaccurate charging control, thereby affecting the safety of lithium batteries. Based on this, the inventors conceived of achieving precise monitoring and control of the negative electrode state of the lithium battery without relying on a reference electrode, thus improving the safety of the lithium battery charging process. The inventors further conceived of obtaining specific responses of the lithium battery negative electrode through impedance testing and dynamic information about the negative electrode state through capacitance testing. Then, by combining the results of impedance and capacitance tests, the charging control can be dynamically adjusted to ensure safe charging of the lithium battery.

[0082] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0083] This application provides a safe charging control method for lithium batteries. First, it should be noted that the safe charging control method for lithium batteries provided in this application is applicable to symmetrical positive and negative electrode batteries, lithium half-cell batteries, and pre-configured three-electrode batteries. In a three-electrode battery, the positive electrode is typically made of materials such as lithium iron phosphate or ternary lithium, the negative electrode is typically made of materials such as graphite, and the reference electrode is typically made of materials such as copper wire, gold wire, or lithium iron phosphate. In a symmetrical positive and negative electrode battery, the positive electrode is made by positive-to-positive and negative-to-negative electrode configurations, while in a lithium half-cell battery, the positive electrode is made by positive-to-lithium electrode and the negative electrode by lithium sheet configurations. It is worth noting that the reference electrode needs to be activated before testing a three-electrode battery; symmetrical positive and negative electrode batteries and lithium half-cell batteries can be tested directly.

[0084] Figure 1 This is a flowchart illustrating the safe charging control method for lithium batteries provided in an embodiment of this application, as shown below. Figure 1 As shown, the safe charging control method for the lithium battery includes:

[0085] S101. Perform impedance testing on the lithium battery to obtain the target voltage interference signal.

[0086] Explained, impedance testing is an electrochemical analysis technique used to measure and analyze the impedance characteristics of batteries or other electrochemical systems. In this embodiment, impedance testing of a lithium battery involves connecting an electrochemical workstation to the lithium battery, applying small-amplitude voltage interference signals at different frequencies, and measuring the battery's response to obtain the battery's impedance.

[0087] An electrochemical workstation is an experimental device used to study and analyze batteries or other electrochemical systems. It includes a frequency response analyzer and a potentiometer. The frequency response analyzer is used to perform impedance testing, applying voltage interference signals to the battery or other electrochemical system at a range of frequencies and measuring the system's response. The potentiometer is used to generate the voltage interference signals.

[0088] Specifically, in this step, a preset voltage interference signal is applied to the lithium battery using the frequency response analyzer of the electrochemical workstation to perform impedance testing. The frequency range of this preset voltage interference signal is usually quite wide, such as 100kHz-0.1mHz.

[0089] Next, the positive and negative impedance response curves of the lithium battery were obtained. The positive impedance response curve represents the change in the positive impedance value as the frequency of the preset voltage interference signal changes. The negative impedance response curve represents the change in the negative impedance value as the frequency of the preset voltage interference signal changes.

[0090] Based on the positive and negative impedance response curves, the desired target voltage interference signal can be determined from the preset voltage interference signals. For clarity, the target voltage interference signal refers to the voltage interference signal when the battery's negative electrode responds and the positive electrode does not.

[0091] It should be understood that determining whether an electrode has an impedance response corresponds to whether the rate of change of the electrode's impedance value changes. In the positive / negative electrode impedance response curve, the rate of change of the impedance value is the slope of the positive / negative electrode impedance response curve. That is to say, if the slope of the positive / negative electrode impedance response curve changes, the point corresponding to the point where the slope changes is the positive / negative electrode impedance response point.

[0092] In this embodiment, the peak values ​​in the positive / negative electrode impedance response curves are defined as the positive / negative electrode impedance responses. Specifically, a first peak value in the positive electrode impedance response curve and a second peak value in the negative electrode impedance response curve are determined. The first peak value indicates the impedance response of the battery's positive electrode, and the second peak value indicates the impedance response of the battery's negative electrode.

[0093] Furthermore, based on the frequency of the preset voltage interference signal corresponding to the first peak and the frequency of the preset voltage interference signal corresponding to the second peak, a target frequency indicating that the battery negative electrode responds while the battery positive electrode does not respond is determined. Then, the portion of the preset voltage interference signal at the target frequency is determined as the target voltage interference signal.

[0094] It should be noted that, to ensure an accurate target voltage interference signal, impedance testing can be performed on the lithium battery at different states of charge (SOC) to obtain the target frequencies corresponding to each charging state, indicating that the negative electrode of the battery responds while the positive electrode does not. Here, the state of charge refers to the ratio of the stored charge of the lithium battery to its maximum capacity; this embodiment does not distinguish between the battery's charge level and the state of charge. Then, these target frequencies are averaged, and the target voltage interference signal is determined based on the averaged frequency.

[0095] Next, a specific example will be used to explain the process of determining the target voltage interference signal by performing impedance testing on a lithium battery under different charging states. In the first example, it is assumed that impedance tests are performed on the lithium battery at charging states of 0%, 20%, 40%, 60%, and 80%, respectively. The preset frequency range of the voltage interference signal is 100kHz-0.1mHz.

[0096] Figure 2 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 1 , Figure 3 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 2 .in, Figure 2 The positive electrode impedance response curves under different charging states are presented. Figure 3 The negative electrode impedance response curves under different charging states are shown. In the figure, f represents the frequency of the preset voltage interference signal, in Hz. This indicates the positive / negative impedance value.

[0097] like Figure 2 As shown, when the frequency of the preset voltage interference signal varies within the range of 100kHz-0.1mHz, the positive electrode impedance response curve does not show a peak, meaning that the battery positive electrode does not exhibit an impedance response. Figure 3As shown, when the frequency of the preset voltage interference signal varies within the range of 100kHz-0.1mHz, the negative electrode impedance response curve shows a peak, indicating that the battery negative electrode exhibits an impedance response. Specifically, when the charging state is 0%, the frequency corresponding to the negative electrode response is 92Hz; when the charging state is 20%, the frequency corresponding to the negative electrode response is 96Hz; when the charging state is 40%, the frequency corresponding to the negative electrode response is 88Hz; when the charging state is 60%, the frequency corresponding to the negative electrode response is 92Hz; and when the charging state is 80%, the frequency corresponding to the negative electrode response is 90Hz.

[0098] Then, the average frequency corresponding to the negative electrode response under different charging states was calculated, yielding a result of 91.6Hz. Therefore, 91.6Hz is the frequency indicating the negative electrode response. Simultaneously, since the positive electrode does not respond when the preset voltage interference signal frequency is 91.6Hz, 91.6Hz is the target frequency indicating the battery's negative electrode response while the positive electrode does not respond. Furthermore, the portion of the preset voltage interference signal below 91.6Hz is determined as the target voltage interference signal.

[0099] S102. During the charging process of the lithium battery, the capacitance of the negative electrode of the lithium battery is tested in real time according to the target voltage interference signal to obtain the capacitance value of the negative electrode of the lithium battery in the current charging state. When it is determined that the capacitance value of the negative electrode of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions, the range of the charge value is determined according to the charge of the lithium battery corresponding to the current charging state.

[0100] Specifically, the process of testing the capacitance of the negative electrode of a lithium battery is as follows: the lithium battery is charged, and a target voltage interference signal is applied to the negative electrode of the lithium battery to obtain the negative electrode capacitance response curve. The negative electrode capacitance response curve characterizes the change in the negative electrode capacitance value of the lithium battery as the state of charge changes.

[0101] Explaining this, after applying a target voltage interference signal to the negative electrode of a lithium battery, what can be directly obtained is the curve showing the change in negative electrode impedance as the state of charge changes. Then, based on the correlation between the negative electrode impedance and the negative electrode capacitance, the curve showing the change in negative electrode impedance as the state of charge changes is converted into a negative electrode capacitance response curve.

[0102] The relationship between the negative electrode impedance and the negative electrode capacitance is as follows: f represents the target frequency of the target voltage interference signal.

[0103] Furthermore, based on the negative electrode capacitor response curve, the negative electrode capacitor value of the lithium battery under the current charging state is obtained. Then, based on the negative electrode capacitor value of the lithium battery under the current charging state and the negative electrode capacitor value of the lithium battery under the next charging state adjacent to the current charging state, the capacitance change rate under the adjacent charging state is calculated.

[0104] If the rate of change of capacitance is greater than a preset threshold, it means that the negative electrode capacitance value of the lithium battery has changed abruptly in the next charging state, i.e., lithium deposition has begun at the negative electrode. At this time, the lithium battery capacity corresponding to the current charging state is determined as the target capacity of the lithium battery. If the rate of change of capacitance is less than or equal to the preset threshold, it means that lithium deposition has not yet begun at the negative electrode. It is necessary to continue analyzing the negative electrode capacitance response curve as the charging state changes until lithium deposition begins at the negative electrode.

[0105] It should be understood that the negative electrode capacitance value of the lithium battery undergoes a sudden change in the next charging state, which, viewed on the negative electrode capacitance response curve, is the inflection point. Therefore, the negative electrode capacitance response curve can also be analyzed through mathematical calculations. Specifically, the second derivative of the negative electrode capacitance response curve is taken, and the point with the largest absolute value of the second derivative is the inflection point of the negative electrode capacitance response curve. The lithium battery capacity corresponding to this inflection point is the target capacity. This application does not limit the method for determining the target capacity of the lithium battery.

[0106] Explanatoryly, lithium plating can affect the impedance characteristics of the negative electrode of a lithium battery, such as increasing the resistance of charge transfer (RCT) or introducing new impedance features. Figure 4 The equivalent circuit diagram of the negative electrode of a lithium battery for the safe charging control method of a lithium battery provided in the embodiments of this application is shown. Figure 4 As shown, the equivalent circuit diagram of the negative electrode of a lithium battery includes two parts of capacitance: the capacitance C corresponding to the solid electrolyte interphase (SEI) film. SEI And the capacitor C corresponding to RCT d .

[0107] It should be noted that, at the target frequency of the target voltage interference signal, the capacitor closely related to lithium plating at the negative electrode of the lithium battery is the capacitor corresponding to Rct. Furthermore, in Figure 4 The equivalent circuit diagram of the negative electrode of the lithium battery is shown below. Indicates ohmic impedance. denoted by , where represents the resistance of the SEI, and W represents Weber diffusion. , The elements W and W are irrelevant to the study in this embodiment and will not be discussed further here.

[0108] It should be noted that different charging rates may be used during the charging process of lithium batteries. Considering this, the capacitance of the negative electrode of the lithium battery can be tested at different charging rates to obtain the target capacity at each rate.

[0109] For example, Figure 5 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 3 , Figure 6 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 4 Assuming charging rates of 2C and 3C are used, a target voltage interference signal is applied to the negative electrode of the lithium battery at different charging rates. The resulting curves show the change in negative electrode impedance as the state of charge changes, as shown below. Figure 5 As shown. Then, based on the relationship between the negative impedance value and the negative capacitance value, [the following is done / is done / etc.]. Figure 5 The curve shown is converted to, Figure 6 The negative capacitor response curves are shown at different charging rates.

[0110] After determining the target capacity, the range of capacity values ​​is determined based on the lithium battery capacity that is less than or equal to the target capacity.

[0111] S103. During the subsequent charging process of the lithium battery, the power of the lithium battery is controlled to be within the power value range.

[0112] Understandably, during the subsequent charging process of lithium batteries, controlling the lithium battery's charge level within a certain range, i.e., controlling the lithium battery's charge level to be less than or equal to the target charge level, can ensure that lithium plating does not occur at the negative electrode of the battery, thereby ensuring the safety of the lithium battery.

[0113] Similarly, to ensure the safe charging of lithium batteries at different charging rates, impedance tests and capacitance tests on the negative electrode of the lithium battery can be performed at different charging rates to determine the range of charge values ​​at different charging rates.

[0114] Furthermore, a battery charging curve, also known as a lithium plating boundary curve, is generated based on the maximum value within the range of charge values ​​at different charging rates. This charging curve represents the change in charging rate as the maximum value within the charge value range changes. During subsequent charging of the lithium battery, controlling the battery charge to remain below the range indicated by the charging curve ensures the safety of the lithium battery.

[0115] For example, Figure 7 A scenario illustration of the safe charging control method for lithium batteries provided in this application embodiment. Figure 5 .like Figure 7As shown, when the charging rate is 3, the maximum value of the charge is 43%; when the charging rate is 2, the maximum value of the charge is 62%; ...; when the charging rate is 0.5, the maximum value of the charge is 93%. The range of charge values ​​less than or equal to those indicated by the lithium plating boundary curve is the safe charging zone, while the range of charge values ​​greater than those indicated by the lithium plating boundary curve is the dangerous charging zone.

[0116] The lithium battery safe charging control method provided in this application applies a preset voltage interference signal to the lithium battery to perform impedance testing, obtaining the positive and negative electrode impedance response curves of the lithium battery. Then, based on the first peak value in the positive electrode impedance response curve and the second peak value in the negative electrode impedance response curve, a target frequency indicating that the battery's negative electrode responds while the positive electrode does not respond is determined. A portion of the signal at the target frequency in the preset voltage interference signal is determined as the target interference signal. Further, during the charging process of the lithium battery, the target voltage interference signal is applied to the negative electrode of the lithium battery to obtain the negative electrode capacitance response curve of the lithium battery, and the negative electrode capacitance value of the lithium battery in the current charging state is obtained based on the negative electrode capacitance response curve. Based on the negative electrode capacitance value of the lithium battery in the current charging state and the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state, the capacitance change rate of the adjacent charging states is calculated. If the capacitance change rate is greater than a preset threshold, the lithium battery capacity corresponding to the current charging state is determined as the target capacity of the lithium battery, and the capacity value range is determined based on the lithium battery capacity that is less than or equal to the target capacity. During the subsequent charging process of the lithium battery, the battery's charge level is controlled within a specified range. By performing impedance and capacitance tests on the lithium battery, the state of the negative electrode can be monitored in real time. Changes in the negative electrode's capacitance value reflect its health and charging status, providing more accurate and dynamic battery status information. Furthermore, this application does not rely on additional hardware, making it more adaptable and easier to integrate into a battery management system for safe lithium battery charging.

[0117] Figure 8 This is a schematic diagram of the structure of the lithium battery safety charging control device provided in the embodiments of this application, as shown below. Figure 8 As shown, the lithium battery safety charging control device 800 includes: a processing module 801, a determination module 802, and a control module 803;

[0118] The processing module 801 is used to perform impedance testing on the lithium battery to obtain the target voltage interference signal; wherein the target voltage interference signal represents the voltage interference signal when the negative electrode of the battery responds and the positive electrode of the battery does not respond.

[0119] The processing module 801 is also used to perform a capacitance test on the negative electrode of the lithium battery in real time according to the target voltage interference signal during the charging process of the lithium battery, so as to obtain the capacitance value of the negative electrode of the lithium battery under the current charging state.

[0120] The determining module 802 is used to determine the range of power values ​​based on the power of the lithium battery corresponding to the current charging state when the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions; wherein, the maximum value in the range of power values ​​is the power of the lithium battery corresponding to the current charging state, and the charging state represents the ratio of the power stored in the lithium battery to the maximum capacity of the lithium battery.

[0121] The control module 803 is used to control the power level of the lithium battery during the subsequent charging process, ensuring that the power level remains within the specified range.

[0122] In one possible design, the processing module 801 is further configured to apply a preset voltage interference signal to the lithium battery to perform impedance testing on the lithium battery and obtain the positive electrode impedance response curve and the negative electrode impedance response curve of the lithium battery; wherein, the positive electrode impedance response curve represents the change of the positive electrode impedance value as the frequency of the preset voltage interference signal changes, and the negative electrode impedance response curve represents the change of the negative electrode impedance value as the frequency of the preset voltage interference signal changes.

[0123] The determination module 802 is also used to determine the target voltage interference signal from the preset voltage interference signal based on the positive impedance response curve and the negative impedance response curve.

[0124] In one possible design, module 802 is also used for:

[0125] Determine the first peak value in the positive electrode impedance response curve and the second peak value in the negative electrode impedance response curve; wherein, the first peak value indicates the impedance response of the battery positive electrode and the second peak value indicates the impedance response of the battery negative electrode, and the impedance response characterizes the change in the rate of change of the impedance value.

[0126] Based on the frequency of the preset voltage interference signal corresponding to the first peak and the frequency of the preset voltage interference signal corresponding to the second peak, a target frequency is determined that indicates the response of the battery negative electrode and the non-response of the battery positive electrode.

[0127] The portion of the preset voltage interference signal at the target frequency is identified as the target voltage interference signal.

[0128] In one possible design, the processing module 801 is also used to apply a target voltage interference signal to the negative electrode of the lithium battery to obtain the negative electrode capacitance response curve of the lithium battery; wherein, the negative electrode capacitance response curve characterizes the change of the negative electrode capacitance value of the lithium battery with the change of the state of charge.

[0129] The processing module 801 further includes an acquisition module 804, used to acquire the negative electrode capacitance value of the lithium battery under the current charging state based on the negative electrode capacitance response curve.

[0130] In one possible design, module 802 is also used for:

[0131] If the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions, then the lithium battery capacity corresponding to the current charging state is determined as the target capacity of the lithium battery.

[0132] The range of battery capacity is determined based on the lithium battery capacity being less than or equal to the target capacity.

[0133] In one possible design, the lithium battery safety charging control device 800 further includes: a calculation module 805, used to calculate the capacitance change rate between adjacent charging states based on the lithium battery negative electrode capacitance value in the current charging state and the lithium battery negative electrode capacitance value in the next charging state.

[0134] The determination module 802 is further configured to determine if the capacitance change rate is greater than a preset threshold, that the negative electrode capacitance value of the lithium battery in the next charging state meets the preset conditions; otherwise, determine that the negative electrode capacitance value of the lithium battery in the next charging state does not meet the preset conditions.

[0135] In one possible design, the processing module 801 is also used for:

[0136] The lithium battery is charged using different charging rates;

[0137] Impedance testing and capacitance testing of the negative electrode of the lithium battery were performed to determine the range of charge values ​​at different charging rates.

[0138] A battery charging curve is generated based on the maximum value of the energy range under different charging rates; the battery charging curve represents the change of charging rate as the maximum value of the energy range changes.

[0139] The control module 803 is also used to control the lithium battery charge during subsequent charging of the lithium battery, keeping it within a range that is less than the charge indicated by the battery charging curve.

[0140] The lithium battery safety charging control device provided in this application embodiment can be used to execute the lithium battery safety charging control method in any of the above embodiments. Its implementation principle and technical effect are similar, and will not be described again here.

[0141] It should be noted that the division of the various modules in the above device is merely a logical functional division. In actual implementation, they can be fully or partially integrated into a single physical entity, or they can be physically separated. Furthermore, these modules can be implemented entirely in software via processing element calls; they can be fully implemented in hardware; or some modules can be implemented by processing element calls to software, while others are implemented in hardware. Additionally, these modules can be fully or partially integrated together, or implemented independently. The processing element mentioned here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each of the above modules can be completed through the integrated logic circuits in the hardware of the processor element or through software instructions.

[0142] Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 9 As shown, the electronic device may include: a transceiver 91, a processor 92, and a memory 93.

[0143] Processor 92 executes computer execution instructions stored in memory, causing processor 92 to perform the scheme in the above embodiments. Processor 92 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0144] The memory 93 is connected to the processor 92 via the system bus and completes communication between them. The memory 93 is used to store computer program instructions.

[0145] Transceiver 91 can be used to communicate and interact with other devices.

[0146] The system bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The system bus can be divided into address bus, data bus, control bus, etc. For ease of representation, only one thick line is used in the diagram, but this does not indicate that there is only one bus or one type of bus. Transceivers are used to enable communication between database access devices and other computers (e.g., clients, read-write libraries, and read-only libraries). Memory may include random access memory (RAM) and may also include non-volatile memory.

[0147] The electronic device provided in this application embodiment can be used to execute the method provided in any of the above embodiments. Its implementation principle and technical effect are similar, and will not be described again here.

[0148] This application also provides a computer-readable storage medium storing computer-executable instructions that, when executed on a computer, cause the computer to perform the method provided in any of the above embodiments.

[0149] This application also provides a computer program product, which includes a computer program stored in a computer-readable storage medium. At least one processor can read the computer program from the computer-readable storage medium, and when the at least one processor executes the computer program, it can implement the method provided in any of the above embodiments.

[0150] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or modules, and may be electrical, mechanical, or other forms.

[0151] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to implement the solution of this embodiment according to actual needs.

[0152] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit. The unit composed of the above modules can be implemented in hardware or in the form of hardware plus software functional units.

[0153] The integrated modules described above, implemented as software functional modules, can be stored in a computer-readable storage medium. These software functional modules, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods of the various embodiments of this application.

[0154] It should be understood that the aforementioned processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly manifested as execution by a hardware processor, or execution by a combination of hardware and software modules within the processor.

[0155] The memory may include high-speed RAM, and may also include non-volatile storage (NVM), such as at least one disk storage device, and may also be a USB flash drive, external hard drive, read-only memory, disk or optical disc, etc.

[0156] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0157] The aforementioned storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0158] An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Alternatively, the storage medium can be an integral part of the processor. The processor and storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and storage medium can exist as discrete components in an electronic control unit or main control device.

[0159] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0160] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A safe charging control method for lithium batteries, characterized in that, include: Impedance testing is performed on the lithium battery to obtain the target voltage interference signal; wherein, the target voltage interference signal characterizes the voltage interference signal when the negative electrode of the battery responds and the positive electrode of the battery does not respond; During the charging process of the lithium battery, the capacitance of the negative electrode of the lithium battery is tested in real time according to the target voltage interference signal to obtain the capacitance value of the negative electrode of the lithium battery in the current charging state. When it is determined that the capacitance value of the negative electrode of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions, the range of the charge value is determined according to the charge of the lithium battery corresponding to the current charging state. The maximum value in the range of the charge value is the charge of the lithium battery corresponding to the current charging state. The charging state represents the ratio of the charge stored in the lithium battery to the maximum capacity of the lithium battery. During the subsequent charging process of the lithium battery, the power level of the lithium battery is controlled to remain within the specified power level range.

2. The method according to claim 1, characterized in that, Impedance testing of the lithium battery yielded the target voltage interference signal, including: A preset voltage interference signal is applied to the lithium battery to perform an impedance test on the lithium battery, thereby obtaining the positive electrode impedance response curve and the negative electrode impedance response curve of the lithium battery; wherein, the positive electrode impedance response curve represents the change of the positive electrode impedance value as the frequency of the preset voltage interference signal changes, and the negative electrode impedance response curve represents the change of the negative electrode impedance value as the frequency of the preset voltage interference signal changes. The target voltage interference signal is determined from the preset voltage interference signal based on the positive impedance response curve and the negative impedance response curve.

3. The method according to claim 2, characterized in that, Based on the positive impedance response curve and the negative impedance response curve, the target voltage interference signal is determined from the preset voltage interference signal, including: Determine the first peak value in the positive electrode impedance response curve and the second peak value in the negative electrode impedance response curve; wherein the first peak value indicates the impedance response of the battery positive electrode and the second peak value indicates the impedance response of the battery negative electrode, and the impedance response characterizes the change in the rate of change of the impedance value; Based on the frequency of the preset voltage interference signal corresponding to the first peak and the frequency of the preset voltage interference signal corresponding to the second peak, a target frequency indicating that the negative electrode of the battery responds and the positive electrode of the battery does not respond is determined. The portion of the preset voltage interference signal at the target frequency is identified as the target voltage interference signal.

4. The method according to claim 1, characterized in that, Based on the target voltage interference signal, the capacitance of the negative electrode of the lithium battery is tested in real time to obtain the capacitance value of the negative electrode of the lithium battery under the current charging state, including: The target voltage interference signal is applied to the negative electrode of the lithium battery to obtain the negative electrode capacitance response curve of the lithium battery; wherein, the negative electrode capacitance response curve characterizes the change of the negative electrode capacitance value of the lithium battery with the change of the state of charge. Based on the negative electrode capacitor response curve, the negative electrode capacitor value of the lithium battery under the current charging state is obtained.

5. The method according to claim 1, characterized in that, When it is determined that the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets a preset condition, the range of the charge value is determined based on the lithium battery charge corresponding to the current charging state, including: If the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions, then the lithium battery capacity corresponding to the current charging state is determined as the target capacity of the lithium battery. The range of power values ​​is determined based on the lithium battery power that is less than or equal to the target power value.

6. The method according to claim 5, characterized in that, Before determining the lithium battery capacity corresponding to the current charging state as the target capacity of the lithium battery if the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets a preset condition, the method further includes: Based on the negative electrode capacitance value of the lithium battery in the current charging state and the negative electrode capacitance value of the lithium battery in the next charging state, calculate the capacitance change rate between adjacent charging states. If the capacitance change rate is greater than a preset threshold, then the negative electrode capacitance value of the lithium battery in the next charging state is determined to meet the preset conditions; otherwise, the negative electrode capacitance value of the lithium battery in the next charging state is determined to not meet the preset conditions.

7. The method according to any one of claims 1 to 6, characterized in that, The method further includes: The lithium battery is charged using different charging rates; Impedance testing is performed on the lithium battery, and capacitance testing is performed on the negative electrode of the lithium battery to determine the range of charge values ​​under different charging rates. A battery charging curve is generated based on the maximum value of the power range under different charging rates; wherein, the battery charging curve represents the change of charging rate as the maximum value of the power range changes; During subsequent charging of the lithium battery, the lithium battery charge is controlled to be within a range lower than the charge indicated by the battery charging curve.

8. A safe charging control device for a lithium battery, characterized in that, include: The processing module is used to perform impedance testing on the lithium battery to obtain the target voltage interference signal; wherein, the target voltage interference signal characterizes the voltage interference signal when the negative electrode of the battery responds and the positive electrode of the battery does not respond. The processing module is also used to perform a capacitance test on the negative electrode of the lithium battery in real time according to the target voltage interference signal during the charging process of the lithium battery, so as to obtain the capacitance value of the negative electrode of the lithium battery under the current charging state. The determining module is used to determine the range of power values ​​based on the power of the lithium battery corresponding to the current charging state when the negative electrode capacitance value of the lithium battery in the next charging state adjacent to the current charging state meets the preset conditions; wherein, the maximum value in the range of power values ​​is the power of the lithium battery corresponding to the current charging state, and the charging state represents the ratio of the power stored in the lithium battery to the maximum capacity of the lithium battery. The control module is used to control the power level of the lithium battery during subsequent charging of the lithium battery, ensuring that the power level remains within the specified range.

9. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the safe charging control method for lithium batteries as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the safe charging control method for a lithium battery as described in any one of claims 1 to 7.

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