Lithium precipitation detection method and system of battery, electronic device and storage medium

Abstract

This application discloses a method, system, electronic device, and storage medium for detecting lithium plating in batteries. The method includes: intermittently charging the battery under test; sampling the pulse current signal and corresponding voltage signal during the intermittent charging process to obtain multiple sampled current signals and sampled voltage signals under various states of charge (SOC); transforming the sampled current signal and sampled voltage signal under each SOC to obtain the electrochemical impedance of the battery under test under each SOC; determining a minimum impedance value within a preset frequency range for each SOC based on the electrochemical impedance of the multiple SOCs; and determining whether lithium plating has occurred in the battery under test based on the variation of the minimum impedance value with the SOC. This application enables real-time lithium plating detection during battery charging, simplifies the detection process, and improves safety during charging.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method, system, electronic device, storage medium, and program product for detecting lithium plating in batteries. Background Technology

[0002] With development, new power systems based on new energy sources are becoming an important choice for sustainable energy development, and the safe and trouble-free operation of energy storage systems is particularly crucial as a key component. During low-temperature or high-rate charging, a large number of lithium ions accumulate on the surface of the graphite negative electrode inside the battery. Because the lithium intercalation reaction rate of the battery is slower than the migration rate of lithium ions to the negative electrode surface, lithium ions may grow in the form of lithium dendrites on the negative electrode surface, resulting in lithium plating. If lithium plating cannot be mitigated or eliminated, the continuous growth of lithium dendrites may puncture the battery separator, causing an internal short circuit in the battery. In severe cases, this may lead to battery fire and explosion, seriously threatening the safe operation of the energy storage system.

[0003] Therefore, in order to reduce the risk of lithium plating during charging, it is often necessary to perform lithium plating detection on the battery. Summary of the Invention

[0004] In view of the above problems, the lithium plating detection method, system, electronic device, storage medium and program product for batteries provided in this application can realize real-time lithium plating detection during battery charging, simplify the detection and improve the safety during the charging process.

[0005] To address the aforementioned problems, this application provides a method for detecting lithium plating in a battery, comprising: intermittently charging the battery under test; sampling the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test to obtain sampling current signals and sampling voltage signals under multiple states of charge; transforming the sampling current signal and sampling voltage signal under each state of charge to obtain the electrochemical impedance of the battery under test under each state of charge; determining a minimum impedance value within a preset frequency range under each state of charge based on the electrochemical impedance of the multiple states of charge, and obtaining the variation law of the minimum impedance value with the state of charge; and determining whether lithium plating has occurred in the battery under test based on the variation law of the minimum impedance value with the state of charge.

[0006] The method of this embodiment samples the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test to obtain multiple sampled current signals and sampled voltage signals under various states of charge. The sampled current signal and sampled voltage signal under each state of charge are transformed to obtain the electrochemical impedance of the battery under test under each state of charge. Based on the electrochemical impedance under multiple states of charge, a minimum impedance value within a preset frequency range is determined for each state of charge, and the variation law of the minimum impedance value with the state of charge is obtained. Based on the variation law of the minimum impedance value with the state of charge, it is determined whether lithium plating has occurred in the energy storage system, thereby achieving real-time lithium plating detection during battery charging, simplifying the detection process, and improving safety during charging.

[0007] In some embodiments, the intermittent charging of the battery under test includes: using a pulse control signal to control the intermittent conduction of a power switch located in the charging circuit of the battery under test to intermittently charge the battery under test. This embodiment achieves intermittent charging by controlling the intermittent conduction of the power switch located in the charging circuit of the battery under test using a pulse control signal. This eliminates the need for an additional dedicated signal generator to apply pulse excitation current or frequency sweep excitation current signals to the battery, does not affect the normal operation of the battery, and thus completes the online lithium plating detection of the battery.

[0008] In some embodiments, sampling the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test includes setting the sampling duration of each state of charge to cover at least one rising edge of the pulse current signal. This embodiment, by setting the sampling duration of each state of charge to cover at least one rising edge of the pulse current signal, enables online lithium plating detection and improves the sensitivity of online lithium plating detection.

[0009] In some embodiments, sampling the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test includes setting the sampling frequency of each state of charge (SOC) to be no less than twice the upper limit of the preset frequency range. This embodiment achieves effective sampling by setting the sampling frequency of each SOC to be no less than twice the upper limit of the preset frequency range, thereby enabling online lithium plating detection and improving the sensitivity of online lithium plating detection.

[0010] In some embodiments, the upper limit of the preset frequency range is between 50-100Hz. This embodiment achieves online lithium plating detection and improves the sensitivity of online lithium plating detection by effectively sampling the upper limit of the preset frequency range, which is between 50-100Hz.

[0011] In some embodiments, sampling the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test includes: setting the plurality of states of charge to be equally spaced, and / or setting the number of the plurality of states of charge to be not less than 5. This embodiment, by setting the plurality of states of charge to be equally spaced, and / or setting the number of the plurality of states of charge to be not less than 5, ensures the quantity of extracted electrochemical impedance, thereby enabling online lithium plating detection and improving the sensitivity of online lithium plating detection.

[0012] In some embodiments, the transformation of the sampled current signal and sampled voltage signal under each of the stated states of charge includes performing complex Morelt wavelet transform on the sampled current signal and sampled voltage signal respectively. This embodiment, by performing complex Morelt wavelet transform on the sampled current signal and sampled voltage signal respectively, can quickly extract the electrochemical impedance of the battery at different frequency components, thereby enabling online lithium plating detection.

[0013] In some embodiments, determining the minimum impedance value within a preset frequency range for each of the plurality of states of charge based on the electrochemical impedance includes: calculating the modulus of the electrochemical impedance based on the real and imaginary parts of the electrochemical impedance, and determining the minimum impedance value based on the modulus of the electrochemical impedance. This embodiment determines the minimum impedance value by using the modulus calculated based on the real and imaginary parts of the electrochemical impedance, which better reflects the variation of electrochemical impedance with frequency under different states of charge (SOC), thereby better determining the minimum impedance value under different SOCs and enabling online lithium plating detection.

[0014] In some embodiments, determining whether the battery under test has undergone lithium plating based on the variation of the minimum impedance value with the state of charge includes: determining that the battery under test has undergone lithium plating in response to the minimum impedance value not showing an increasing trend with the increase of the state of charge. This embodiment, by determining that the battery under test has undergone lithium plating based on the minimum impedance value not showing an increasing trend with the increase of the state of charge, enables online lithium plating detection.

[0015] To address the aforementioned problems, this application provides a lithium plating detection system for batteries, comprising: an intermittent charging module for intermittently charging the battery under test; a sampling module for sampling pulse current signals and corresponding voltage signals during the intermittent charging process of the battery under test to obtain sampling current signals and sampling voltage signals under multiple states of charge; a transformation module for transforming the sampling current signals and sampling voltage signals under each state of charge to obtain the electrochemical impedance of the battery under test under each state of charge; a minimum impedance value determination module for determining a minimum impedance value within a preset frequency range under each state of charge based on the electrochemical impedance under the multiple states of charge, and obtaining the variation law of the minimum impedance value with the state of charge; and a lithium plating judgment module for judging whether lithium plating has occurred in the battery under test based on the variation law of the minimum impedance value with the state of charge.

[0016] To address the aforementioned problems, this application provides an electronic device, including a memory and a processor, wherein the processor is configured to execute program instructions stored in the memory to implement a lithium plating detection method for a battery as described above.

[0017] To address the aforementioned problems, this application provides a computer-readable storage medium storing program instructions thereon, characterized in that, when the program instructions are executed by a processor, they implement a lithium plating detection method for a battery as described above.

[0018] To address the aforementioned problems, this application provides a computer program product, comprising a computer program, characterized in that, when the computer program is executed by a processor, it implements a lithium plating detection method for a battery as described above.

[0019] By sampling the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test, multiple sampling current signals and sampling voltage signals under different states of charge are obtained. The sampling current signal and sampling voltage signal under each state of charge are transformed to obtain the electrochemical impedance of the battery under test under each state of charge. Based on the electrochemical impedance under multiple states of charge, a minimum impedance value within a preset frequency range is determined for each state of charge, and the variation law of the minimum impedance value with the state of charge is obtained. Based on the variation law of the minimum impedance value with the state of charge, it is determined whether lithium plating has occurred in the energy storage system, thereby achieving real-time lithium plating detection during battery charging, simplifying detection, and improving safety during the charging process. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0021] Figure 1 This is a schematic flowchart of a lithium plating detection method for batteries according to an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the battery structure according to an embodiment of this application;

[0023] Figure 3 This is a schematic diagram of intermittent charging of a battery according to an embodiment of this application;

[0024] Figure 4 This is a schematic diagram of a battery charging circuit according to an embodiment of this application;

[0025] Figure 5 This is a schematic diagram of the charging circuit of another battery according to an embodiment of this application;

[0026] Figure 6 This is a schematic diagram of the minimum impedance value of the battery in an embodiment of this application as a function of SOC.

[0027] Figure 7 This is a schematic diagram of the minimum impedance value of the battery in an embodiment of this application as a function of SOC.

[0028] Figure 8 This is a schematic flowchart of the lithium plating detection process for batteries according to an embodiment of this application;

[0029] Figure 9 This is a schematic diagram of the lithium plating detection system for batteries according to an embodiment of this application;

[0030] Figure 10 This is a schematic diagram of the structure of an electronic device according to an embodiment of this application;

[0031] Figure 11 This is a schematic diagram of the structure of a computer-readable storage medium according to an embodiment of this application. Detailed Implementation

[0032] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having" and any variations thereof in the specification, claims and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0034] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0035] In this document, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0036] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0037] In the description of the embodiments of this application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0038] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0039] Conventional lithium plating detection methods often require disassembling the battery for in-situ testing or can only be performed after charging is complete, but cannot be performed during charging, which increases the risk of safety malfunctions in energy storage systems. Currently, methods for lithium plating detection during charging have emerged, requiring the additional superposition of excitation signals at different frequencies onto the charging current to calculate the battery's electrochemical impedance spectroscopy (EIS) for lithium plating detection. However, this requires a dedicated signal generator, and the signal generator needs to acquire data multiple times before EIS calculation can be performed, placing high demands on the signal generator and making the calculation process quite complex.

[0040] Based on the above considerations, this application provides a method for detecting lithium plating in a battery. The method involves sampling the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test to obtain multiple sampling current and voltage signals under different states of charge (SOC). The sampling current and voltage signals under each SOC are then transformed to obtain the electrochemical impedance of the battery under test at each SOC. Based on the electrochemical impedance under multiple SOCs, a minimum impedance value within a preset frequency range is determined for each SOC, revealing the variation of the minimum impedance value with the SOC. Based on this variation, it is determined whether lithium plating has occurred in the energy storage system, thereby achieving real-time lithium plating detection during battery charging, simplifying the detection process, and improving safety during charging.

[0041] Please refer to Figure 1 , Figure 1 This is a schematic flowchart of a lithium plating detection method for a battery according to an embodiment of this application. The method includes: Step S101: Intermittently charging the battery to be tested. Step S102: Sampling the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery to be tested to obtain sampling current signals and sampling voltage signals under multiple states of charge. Step S103: Transforming the sampling current signal and sampling voltage signal under each state of charge to obtain the electrochemical impedance of the battery to be tested under each state of charge. Step S104: Based on the electrochemical impedance under multiple states of charge, determining the minimum impedance value within a preset frequency range under each state of charge, and obtaining the variation law of the minimum impedance value with the state of charge. Step S105: Based on the variation law of the minimum impedance value with the state of charge, determining whether lithium plating has occurred in the battery to be tested.

[0042] The battery or the battery under test can be an energy storage device or energy storage system. Energy storage devices include energy storage containers, energy storage cabinets, etc. Please refer to [reference needed]. Figure 2The energy storage device or system can be a multi-cell cluster system composed of multiple cells (Cell 1-Cell N) connected in series. Alternatively, it can be a multi-cell cluster system composed of multiple cells connected in parallel or a multi-cell cluster system composed of multiple cells connected in series and parallel.

[0043] Intermittent charging of the battery under test, for example, for... Figure 2 For intermittent charging of energy storage devices or systems, please refer to [the relevant documentation / reference]. Figure 3 The diagram illustrates the intermittent charging process, including pulse current signals and corresponding voltage signals. During intermittent charging, the pulse current signals and corresponding voltage signals are sampled to obtain sampled current and voltage signals at multiple states of charge (SOC). In other words, the sampled current and voltage signals are obtained by sampling the pulse current and corresponding voltage signals during the intermittent charging process of the battery under test. Through transformation, specifically time-frequency transformation, the electrochemical impedance spectroscopy (EIS) of the battery at different frequencies under different SOCs is calculated; that is, the curves showing the electrochemical impedance as a function of frequency at different SOCs, thus obtaining the electrochemical impedance at different SOCs.

[0044] Based on the electrochemical impedance at multiple states of charge (SOCs), the minimum impedance value within a preset frequency range is determined for each SOC. For example, the minimum impedance value within the low-to-mid frequency range is determined for each SOC. The minimum impedance value within the preset frequency range refers to the lowest impedance value within that range. Therefore, minimum impedance values ​​at different SOCs are obtained, meaning different SOCs have different minimum impedance values. Based on the variation of the minimum impedance value with different SOCs, it can be determined whether lithium plating has occurred in the battery under test.

[0045] In this embodiment, the lithium plating detection method for batteries samples the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test to obtain multiple sampled current signals and sampled voltage signals under various states of charge. The sampled current signal and sampled voltage signal under each state of charge are then transformed to obtain the electrochemical impedance of the battery under test under each state of charge. Based on the electrochemical impedance under multiple states of charge, a minimum impedance value within a preset frequency range is determined for each state of charge, and the variation law of the minimum impedance value with the state of charge is analyzed. Based on the variation law of the minimum impedance value with the state of charge, it is determined whether lithium plating has occurred in the energy storage system, thereby achieving real-time lithium plating detection during battery charging, simplifying the detection process, and improving safety during charging.

[0046] In some embodiments, intermittent charging of the battery under test includes: using a pulse control signal to control a power switch located in the charging circuit of the battery under test to intermittently turn on to intermittently charge the battery under test.

[0047] The battery under test is connected to a power module to form a charging circuit for the circuit under test. The power module includes a power switch, thus the charging circuit includes a power switch. Please refer to [reference needed]. Figure 4 The charging circuit includes two power switches, IGBT 1 and IGBT 2. Of course, the charging circuit can also include other numbers of power switches; please refer to [reference needed]. Figure 5 The charging circuit includes four power switches. The number of power switches can be determined based on the configuration of the battery's multi-cell structure.

[0048] The power module of the battery under test may also include other components, for example, please refer to Figure 4 and Figure 5 The power module also includes capacitors.

[0049] Intermittent charging is achieved by controlling the intermittent conduction of the power switch in the charging circuit using a pulse control signal. For example, controlling the switching of the power switch in the charging circuit causes it to conduct intermittently, thus realizing intermittent charging. Please refer to [link / reference]. Figure 4 and Figure 5 The power switch can be an IGBT (Insulated Gate Bipolar Transistor). Of course, the power switch can be other types of power switching devices, such as thyristors, field-effect transistors, bipolar transistors, etc.

[0050] In this embodiment, the power switch in the charging circuit of the battery under test is intermittently turned on by a pulse control signal to achieve intermittent charging. No additional dedicated signal generator is needed to apply pulse excitation current or frequency sweep excitation current signal to the battery, and the normal operation of the battery is not affected. The online lithium plating detection of the battery can be completed.

[0051] In some embodiments, sampling the pulse current signal and the corresponding voltage signal during the intermittent charging process of the battery under test includes setting the sampling duration of each state of charge to cover at least one rising edge of the pulse current signal.

[0052] During intermittent charging, the pulse current signal and the corresponding voltage signal are sampled to obtain sampled current signals and sampled voltage signals under different SOCs. The sampling duration of each SOC covers the rising edge of the pulse current signal during the intermittent charging process.

[0053] In this embodiment, by setting the sampling duration of each state of charge to cover at least one rising edge of the pulse current signal, online lithium plating detection can be achieved, and the sensitivity of online lithium plating detection can be improved.

[0054] In some embodiments, sampling the pulse current signal and the corresponding voltage signal during the intermittent charging process of the battery under test includes setting the sampling frequency of each state of charge to be not less than twice the upper value of a preset frequency range.

[0055] The preset frequency range can be a low-to-mid frequency range, such as below 100Hz, including 100Hz. The upper limit of the low-to-mid frequency range is the maximum value of the range. For example, if the low-to-mid frequency range is 40-80Hz, then the upper limit of the low-to-mid frequency range is 80Hz.

[0056] During intermittent charging, the pulse current signal and the corresponding voltage signal are sampled to obtain sampled current and voltage signals under different states of charge (SOC). The sampling frequency for each SOC is no less than twice the upper limit of a preset frequency range, conforming to the sampling theorem for continuous signals. For example, if the upper limit of the low-to-mid frequency range is 80Hz, the sampling frequency can be 10kHz, which is more than twice the upper limit (80Hz).

[0057] In this embodiment, by setting the sampling frequency of each SOC to no less than twice the upper value of the preset frequency range, effective sampling can be performed, thereby enabling online lithium plating detection and improving the sensitivity of online lithium plating detection.

[0058] In some embodiments, the upper limit of the preset frequency range is between 50-100Hz.

[0059] The upper limit of the low-to-mid frequency range, i.e., the maximum value of the low-to-mid frequency range. The preset frequency range can be a low-to-mid frequency range, for example, below 100Hz, including 100Hz. For example, if the low-to-mid frequency range is 40-80Hz, then the upper limit of the low-to-mid frequency range is 80Hz.

[0060] In this embodiment, by effectively sampling the upper end of the preset frequency range, which is between 50-100Hz, online lithium plating detection can be achieved, and the sensitivity of online lithium plating detection can be improved.

[0061] In some embodiments, sampling the pulse current signal and the corresponding voltage signal during the intermittent charging process of the battery to be tested includes: setting multiple states of charge to be equally spaced, and / or setting the number of multiple states of charge to be not less than 5.

[0062] During the sampling of the entire intermittent charging process, the range of multiple SOCs can be 20%-80%, that is, 20% SOC to 80% SOC, or 20%-100%, that is, 20% SOC to 100% SOC.

[0063] Multiple SOCs are distributed at equal intervals, meaning they are sampled uniformly throughout the intermittent charging process. This equal-interval distribution of multiple SOCs can be done at 10% SOC intervals. For example, if the range of multiple SOCs is 20%-80%, the multiple SOCs could be 20%, 30%, 40%, 50%, 60%, 70%, and 80%, or 35%, 45%, 55%, 65%, and 75%. Of course, multiple SOCs can also be distributed at other intervals, such as 15% SOC intervals.

[0064] The number of states of charge (SOCs) should be set to no less than five, meaning that the entire intermittent charging process should be sampled at least five times. The number of SOCs can be five; for example, if the range of SOCs is 20%-80%, the SOCs could be 30%, 40%, 50%, 60%, or 70%, or 20%, 30%, 50%, 70%, or 80%. Of course, the number of SOCs can also be other values, such as seven.

[0065] In this embodiment, by setting multiple states of charge to be equally spaced and / or setting the number of multiple states of charge to not less than 5, the amount of extracted electrochemical impedance can be ensured, thereby enabling online lithium plating detection and improving the sensitivity of online lithium plating detection.

[0066] In some embodiments, transforming the sampled current signal and sampled voltage signal under each charged state includes performing complex Morelt wavelet transform on the sampled current signal and sampled voltage signal respectively.

[0067] To facilitate the explanation of the complex Morelt wavelet transform, the wavelet transform (WT) will be described first below.

[0068] Wavelet transform (WT) is a waveform analysis method for time-domain signals. In WT, wavelet coefficients can be obtained by convolving and integrating the mother wavelet function with the original time-domain signal. Specifically, the wavelet transform of a continuous time-domain signal f(t) is defined by formula (1):

[0069]

[0070] Among them, WT f (a, b) represent the wavelet transform coefficients of the continuous time-domain signal f(t); Represents ψ a，b The complex conjugate of (t); ψa，b (t) represents a series of sub-wavelet basis functions obtained by stretching and translating the mother wavelet basis function, which can be expressed as the following formula (2):

[0071]

[0072] The complex Morlet wavelet is a complex-valued wavelet basis function adjusted by a Gaussian function. Its imaginary part is a Hilbert transform of the real part, satisfying the properties of complex value and non-orthogonality, making it suitable for impedance calculation. The complex Morlet wavelet basis function is the product of a Gaussian function and a sine term, as shown in equations (3), (4), and (5), respectively:

[0073]

[0074]

[0075] h(t m )=exp(j2πf c t m (5),

[0076] Where j represents the imaginary unit; f b The frequency band parameter represents the time range related to the Gaussian window; the temporal resolution of data sampling can be determined by f. b To define; the mid-frequency band parameter f of the Gaussian function b The relationship between the standard deviation σ and the standard deviation σ is expressed as in formula (6):

[0077]

[0078] t m The time of the mother wavelet is expressed by formula (7):

[0079]

[0080] 'a' represents the scaling factor, which affects the shape of the sub-wavelet. When 'a' is large, the mother wavelet has a wider Gaussian window in the time domain, resulting in lower time resolution, but a clearer distribution in the frequency domain, i.e., higher frequency resolution. In contrast, when 'a' is small, the mother wavelet has a narrower Gaussian window in the time domain, resulting in higher time resolution but lower frequency resolution. 'b' represents the translation parameter, which affects the center position of the sub-wavelet but has no effect on the wavelet waveform. Both 'a' and 'b' are real numbers, and 'a' is greater than zero.

[0081] f represents the center frequency, and is related to a and f c The relationship is shown in formula (8):

[0082]

[0083] Therefore, based on the above, the wavelet transform coefficients of the square wave excitation current i(t) and the corresponding voltage u(t) at different frequencies are calculated as shown in the following formulas (9) and (10), and can be calculated by adjusting the parameters a and b.

[0084]

[0085]

[0086] Subsequently, by dividing the wavelet transform coefficients of voltage and current at different frequencies, the electrochemical impedance at different frequencies is obtained, and its calculation formula is shown in equation (11):

[0087]

[0088] Therefore, the curve of electrochemical impedance spectroscopy (EIS) versus frequency under a specific state of charge (SOC) can be obtained, i.e., the EIS under that SOC. First, the sampled current and voltage signals under a certain SOC are calculated using the complex Morlet wavelet transform described above to obtain the EIS under that SOC. Then, the same complex Morlet wavelet transform is performed on the sampled current and voltage signals under other SOCs to obtain the EIS under those other SOCs. In this way, the electrochemical impedance spectroscopy under multiple SOCs is obtained. Of course, other time-frequency transforms can also be used, such as wavelet transforms, Fourier transforms, etc.

[0089] In this embodiment, by performing complex Morelt wavelet transform on the sampled current signal and the sampled voltage signal respectively, the electrochemical impedance of the battery at different frequency components can be quickly extracted, thereby enabling online lithium plating detection.

[0090] In some embodiments, determining the minimum impedance value for a preset frequency range under each charged state based on the electrochemical impedance under multiple charged states includes: calculating the modulus of the electrochemical impedance based on the real and imaginary parts of the electrochemical impedance, and determining the minimum impedance value based on the modulus of the electrochemical impedance.

[0091] By transforming the sampled current and voltage signals under SOC (State of Charge), the resulting electrochemical impedance under SCO (Solution of Circulation) is a complex number, including real and imaginary parts. Based on the modulus calculated from the real and imaginary parts of the electrochemical impedance, the minimum impedance value within a preset frequency range under this SOC is determined, for example, the minimum impedance value in the low-to-mid frequency range. In this case, the minimum impedance value refers to the smallest modulus within that preset frequency range. Alternatively, the minimum impedance value can also be determined based on either the imaginary or real part of the electrochemical impedance.

[0092] In this embodiment, the minimum impedance value is determined by calculating the modulus based on the real and imaginary parts of the electrochemical impedance, which better reflects the variation of electrochemical impedance with frequency under different SOCs, thereby better determining the minimum impedance value under different SOCs, so as to realize online lithium plating detection.

[0093] In some embodiments, determining whether lithium plating has occurred in the energy storage system based on the variation of the minimum impedance value with the state of charge includes: determining that lithium plating has occurred in the battery under test in response to the fact that the minimum impedance value does not show an increasing trend with the increase of the state of charge.

[0094] Different states of charge (SOC) have different minimum impedance values. Therefore, based on the variation of the minimum impedance value with different SOCs, it can be determined whether lithium plating has occurred in the battery under test. Specifically, if the minimum impedance value does not show an increasing trend with increasing SOC, the battery under test is determined to have undergone lithium plating; if the minimum impedance value shows an increasing trend with increasing SOC, the battery under test is determined not to have undergone lithium plating.

[0095] Please refer to Figure 6 If the minimum impedance value does not increase with increasing SOC, then lithium plating is considered to have occurred in the battery. Please refer to... Figure 7 The minimum impedance value increases with the increase of SOC. At this point, it is determined that the corresponding battery has not undergone lithium plating.

[0096] In this embodiment, the lithium plating of the battery under test is determined by the fact that the minimum impedance value does not show an increasing trend with the increase of the state of charge, thus enabling online lithium plating detection.

[0097] In some embodiments, please refer to Figure 8 The online lithium plating detection process for batteries includes the following steps:

[0098] Step S801: The power switch in the charging circuit of the battery under test is switched on and off to intermittently charge the circuit under test, thereby generating pulse current signals and corresponding voltage signals.

[0099] Step S802: Determine whether the battery under test has reached the charging cutoff condition, such as whether the battery is fully charged or whether the charging end time has been reached. If the battery under test has not reached the charging cutoff condition, proceed to step S803; if the battery under test has reached the charging cutoff condition, end the process.

[0100] Step S803: Sample the pulse current signal and corresponding voltage signal during the charging process multiple times to obtain sampled current and voltage signals under multiple SOCs. Each sampling operation involves sampling the sampled current and voltage signals under one SOC. The sampling duration of each sampling covers at least one rising edge of the pulse current signal, and the sampling frequency is not less than twice the upper limit of a preset frequency range. Multiple samples are evenly spaced, meaning the multiple SOCs are uniformly distributed, and / or the number of sampling operations is not less than 5, meaning the number of multiple SOCs is not less than 5.

[0101] Step S804: Perform complex Morelt wavelet transform on the sampled current signals and sampled voltage signals under multiple SOCs respectively to obtain the EIS under multiple SOCs. The complex Morelt wavelet transform will not be described here.

[0102] Step S805: Based on EIS under multiple SOCs, identify the minimum impedance value in the low-to-mid frequency range of the battery under test.

[0103] Step S806: Determine whether the minimum impedance value does not show an increasing trend as a function of multiple SOCs, thereby determining whether lithium plating has occurred in the battery under test. If the minimum impedance value does not show an increasing trend as a function of multiple SOCs, proceed to step S807, at which point the process ends. If the minimum impedance value shows an increasing trend as a function of multiple SOCs, the battery under test has not undergone lithium plating. In this case, re-execute step S801 to re-detect lithium plating.

[0104] Step S807: Lithium plating occurs in the battery under test.

[0105] Please refer to Figure 9 , Figure 9This is a schematic diagram of the lithium plating detection system for a battery according to an embodiment of this application. The lithium plating detection system 900 is connected to the battery under test and includes: an intermittent charging module 901, a sampling module 902, a transformation module 903, a minimum impedance value determination module 904, and a lithium plating judgment module 905. The intermittent charging module 901 is used to intermittently charge the battery under test. The sampling module 902 is used to sample the pulse current signal and the corresponding voltage signal during the intermittent charging process of the battery under test to obtain sampling current signals and sampling voltage signals under multiple states of charge. The transformation module 903 is used to transform the sampling current signal and sampling voltage signal under each state of charge to obtain the electrochemical impedance of the battery under test under each state of charge. The minimum impedance value determination module 904 is used to determine the minimum impedance value within a preset frequency range under each state of charge based on the electrochemical impedance under multiple states of charge, and to obtain the variation law of the minimum impedance value with the state of charge. The lithium plating detection module 905 is used to determine whether lithium plating has occurred in the battery under test based on the change law of the minimum impedance value with the state of charge.

[0106] In this embodiment, the pulse current signal and corresponding voltage signal of the battery under test during the intermittent charging process are sampled to obtain multiple sampled current signals and sampled voltage signals under various states of charge. The sampled current signal and sampled voltage signal under each state of charge are transformed to obtain the electrochemical impedance of the battery under test under each state of charge. Based on the electrochemical impedance under multiple states of charge, the minimum impedance value within a preset frequency range under each state of charge is determined, and the variation law of the minimum impedance value with the state of charge is obtained. Based on the variation law of the minimum impedance value with the state of charge, it is determined whether lithium plating has occurred in the energy storage system, thereby realizing real-time lithium plating detection during battery charging, simplifying the detection process, and improving the safety of the charging process.

[0107] In some embodiments, the intermittent charging module 901 is used to control the power switch in the charging circuit of the battery under test to be intermittently turned on by using a pulse control signal to intermittently charge the battery under test.

[0108] In this embodiment, the power switch in the charging circuit of the battery under test is intermittently turned on by a pulse control signal to achieve intermittent charging. No additional dedicated signal generator is needed to apply pulse excitation current or frequency sweep excitation current signal to the battery, and the normal operation of the battery is not affected. The online lithium plating detection of the battery can be completed.

[0109] In some embodiments, the sampling module 902 is configured to set the sampling duration of each state of charge to cover at least one rising edge of the pulse current signal.

[0110] In this embodiment, by setting the sampling duration of each state of charge to cover at least one rising edge of the pulse current signal, online lithium plating detection can be achieved, and the sensitivity of online lithium plating detection can be improved.

[0111] In some embodiments, the sampling module 902 is used to set the sampling frequency of each state of charge to be no less than twice the upper value of a preset frequency range.

[0112] In this embodiment, by setting the sampling frequency of each SOC to no less than twice the upper value of the preset frequency range, effective sampling can be performed, thereby enabling online lithium plating detection and improving the sensitivity of online lithium plating detection.

[0113] In some embodiments, the upper limit of the preset frequency range is between 50-100Hz.

[0114] In this embodiment, by effectively sampling the upper end of the preset frequency range, which is between 50-100Hz, online lithium plating detection can be achieved, and the sensitivity of online lithium plating detection can be improved.

[0115] In some embodiments, the sampling module 902 is used to set multiple states of charge to be equally spaced, and / or to set the number of multiple states of charge to be not less than 5.

[0116] In this embodiment, by setting multiple states of charge to be equally spaced and / or setting the number of multiple states of charge to not less than 5, the amount of extracted electrochemical impedance can be ensured, thereby enabling online lithium plating detection and improving the sensitivity of online lithium plating detection.

[0117] In some embodiments, the transformation module 903 is used to perform complex Morelt wavelet transform on the sampled current signal and the sampled voltage signal, respectively.

[0118] In this embodiment, by performing complex Morelt wavelet transform on the sampled current signal and the sampled voltage signal respectively, the electrochemical impedance of the battery at different frequency components can be quickly extracted, thereby enabling online lithium plating detection.

[0119] In some embodiments, the minimum impedance value determination module 904 is used to calculate the modulus of the electrochemical impedance based on the real and imaginary parts of the electrochemical impedance, and to determine the minimum impedance value based on the modulus of the electrochemical impedance.

[0120] In this embodiment, the minimum impedance value is determined by calculating the modulus based on the real and imaginary parts of the electrochemical impedance, which better reflects the variation of electrochemical impedance with frequency under different SOCs, thereby better determining the minimum impedance value under different SOCs, so as to realize online lithium plating detection.

[0121] In some embodiments, the lithium plating determination module 905 is used to determine that the battery under test has undergone lithium plating in response to the fact that the minimum impedance value does not show an increasing trend with the increase of the state of charge.

[0122] In this embodiment, the lithium plating of the battery under test is determined by the fact that the minimum impedance value does not show an increasing trend with the increase of the state of charge, thus enabling online lithium plating detection.

[0123] Please see Figure 10 , Figure 10 This is a schematic diagram of the structure of an electronic device according to an embodiment of this application. The electronic device 1000 includes a memory 1001 and a processor 1002. The processor 1002 is used to execute program instructions stored in the memory 1001 to implement the steps in any of the above-described embodiments of the lithium plating detection method for batteries. In a specific implementation scenario, the electronic device 1000 may include, but is not limited to, a microcomputer or a server. Furthermore, the electronic device 1000 may also include a laptop computer, tablet computer, or other supporting device; no further limitations are imposed here.

[0124] Specifically, processor 1002 controls itself and memory 1001 to implement the steps in any of the above-described lithium plating detection method embodiments for batteries. Processor 1002 can also be referred to as a CPU (Central Processing Unit). Processor 1002 may be an integrated circuit chip with signal processing capabilities. Processor 1002 can also be a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. A general-purpose processor can be a microprocessor or any conventional processor. Furthermore, processor 1002 can be implemented using integrated circuit chips.

[0125] In this embodiment, the pulse current signal and corresponding voltage signal of the battery under test during the intermittent charging process are sampled to obtain multiple sampled current signals and sampled voltage signals under various states of charge. The sampled current signal and sampled voltage signal under each state of charge are transformed to obtain the electrochemical impedance of the battery under test under each state of charge. Based on the electrochemical impedance under multiple states of charge, the minimum impedance value within a preset frequency range under each state of charge is determined, and the variation law of the minimum impedance value with the state of charge is obtained. Based on the variation law of the minimum impedance value with the state of charge, it is determined whether lithium plating has occurred in the energy storage system, thereby realizing real-time lithium plating detection during battery charging, simplifying the detection process, and improving the safety of the charging process.

[0126] Please see Figure 11 , Figure 11 This is a schematic diagram of the structure of a computer-readable storage medium according to an embodiment of this application. The computer-readable storage medium 1100 stores program instructions 1101 thereon. When the program instructions 1101 are executed by a processor, they implement the steps in any of the above-described embodiments of the lithium plating detection method for batteries.

[0127] In this embodiment, the pulse current signal and corresponding voltage signal of the battery under test during the intermittent charging process are sampled to obtain multiple sampled current signals and sampled voltage signals under various states of charge. The sampled current signal and sampled voltage signal under each state of charge are transformed to obtain the electrochemical impedance of the battery under test under each state of charge. Based on the electrochemical impedance under multiple states of charge, the minimum impedance value within a preset frequency range under each state of charge is determined, and the variation law of the minimum impedance value with the state of charge is obtained. Based on the variation law of the minimum impedance value with the state of charge, it is determined whether lithium plating has occurred in the energy storage system, thereby realizing real-time lithium plating detection during battery charging, simplifying the detection process, and improving the safety of the charging process.

[0128] This application embodiment may also provide a computer program product, which can be executed by a processor, and when the computer program product is executed, the above-mentioned lithium plating detection method for batteries can be implemented.

[0129] In some embodiments, the functions or modules of the apparatus provided in this disclosure can be used to perform the methods described in the above method embodiments. The specific implementation can be referred to the description of the above method embodiments, and for the sake of brevity, it will not be repeated here.

[0130] The description of the various embodiments above tends to emphasize the differences between the various embodiments. The similarities or similarities between them can be referred to, and for the sake of brevity, they will not be repeated here.

[0131] In the several embodiments provided in this application, it should be understood that the disclosed methods and apparatus can be implemented in other ways. For example, the apparatus implementations described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, units or components may be combined or integrated into another system, or some features may be ignored or not executed. In another image location, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0132] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A method for detecting lithium plating in batteries, characterized in that, include: The battery to be tested is charged intermittently; The pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test are sampled to obtain multiple sampled current signals and sampled voltage signals under multiple states of charge. The sampled current signal and sampled voltage signal under each of the stated states of charge are transformed to obtain the electrochemical impedance of the battery under test under each of the stated states of charge. Based on the electrochemical impedance of the multiple states of charge, the minimum impedance value within a preset frequency range for each state of charge is determined, and the variation law of the minimum impedance value with the state of charge is obtained. Based on the variation of the minimum impedance value with the state of charge, it is determined whether the battery under test has undergone lithium plating.

2. The method according to claim 1, characterized in that, The intermittent charging of the battery to be tested includes: The battery under test is intermittently charged by using a pulse control signal to control the power switch in the charging circuit of the battery under test to be intermittently turned on.

3. The method according to claim 1 or 2, characterized in that, The sampling of the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test includes: The sampling duration for each of the stated states of charge is set to cover at least one rising edge of the pulse current signal.

4. The method according to claim 3, characterized in that, The sampling of the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test includes: The sampling frequency for each of the stated states of charge is set to be no less than twice the upper limit of the preset frequency range.

5. The method according to claim 4, characterized in that, The upper limit of the preset frequency range is between 50-100Hz.

6. The method according to any one of claims 1-5, characterized in that, The sampling of the pulse current signal and corresponding voltage signal during the intermittent charging process of the battery under test includes: The plurality of states of charge are set to be equally spaced, and / or The number of the plurality of states of charge is set to be no less than 5.

7. The method according to any one of claims 1-6, characterized in that, The transformation of the sampled current signal and sampled voltage signal under each of the charged states includes: The sampled current signal and the sampled voltage signal are subjected to complex Morelt wavelet transform respectively.

8. The method according to any one of claims 1-7, characterized in that, The step of determining the minimum impedance value within a preset frequency range for each of the multiple states of charge based on the electrochemical impedance includes: The modulus of the electrochemical impedance is calculated based on the real and imaginary parts of the electrochemical impedance, and the minimum impedance value is determined based on the modulus of the electrochemical impedance.

9. The method according to any one of claims 1-8, characterized in that, The step of determining whether the battery under test has undergone lithium plating based on the variation of the minimum impedance value with the state of charge includes: If the minimum impedance value does not increase with the increase of the state of charge, it is determined that the battery under test has undergone lithium plating.

10. A lithium plating detection system for batteries, characterized in that, include: An intermittent charging module is used to intermittently charge the battery under test. The sampling module is used to sample the pulse current signal and the corresponding voltage signal during the intermittent charging process of the battery under test, and obtain the sampling current signal and sampling voltage signal under multiple states of charge. The transformation module is used to transform the sampled current signal and sampled voltage signal under each of the charging states to obtain the electrochemical impedance of the battery under test under each of the charging states. The minimum impedance value determination module is used to determine the minimum impedance value within a preset frequency range for each of the multiple states of charge based on the electrochemical impedance, and to obtain the variation law of the minimum impedance value with the state of charge. The lithium plating detection module is used to determine whether lithium plating has occurred in the battery under test based on the change law of the minimum impedance value with the state of charge.

11. An electronic device, characterized in that, The device includes a memory and a processor, the processor being configured to execute program instructions stored in the memory to implement a lithium plating detection method for a battery as described in any one of claims 1 to 9.

12. A computer-readable storage medium having program instructions stored thereon, characterized in that, When the program instructions are executed by the processor, they implement a lithium plating detection method for a battery as described in any one of claims 1 to 9.

13. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements a lithium plating detection method for a battery according to any one of claims 1 to 9.

Images