Battery charging method, system, vehicle and medium based on lithium plating detection

Abstract

The present invention discloses a battery charging method, system, automobile and medium based on lithium deposition detection. The method obtains a battery charging strategy table after receiving a battery charging instruction; charges the battery according to the charging current in the battery charging strategy table, and performs at least one charging lithium deposition detection on the battery during the battery charging process to obtain a first lithium deposition detection result; when the first lithium deposition detection result is that no lithium deposition phenomenon occurs, the battery is continuously charged according to the charging current, and the battery is continuously charged with lithium deposition detection until the first lithium deposition detection result is that lithium deposition phenomenon occurs, or until the battery is completely charged, the charging lithium deposition detection is stopped; when the first lithium deposition detection result is that lithium deposition phenomenon occurs, the charging current in the battery charging strategy table is updated according to a preset first current reduction strategy, and the battery is continuously charged according to the updated charging current until charging is completed. The present invention improves the safety of battery charging.

Description

Technical Field

[0001] The present invention relates to the technical field of battery charging, and in particular to a battery charging method, system, vehicle and medium based on lithium plating detection. Background Art

[0002] With the development of science and technology, new energy vehicles are developing more and more rapidly. As an important part of new energy vehicles, users have higher requirements on the charging time of car batteries. Further shortening the battery charging time can effectively improve the user's car experience.

[0003] In the prior art, the methods for realizing fast charging of batteries mainly include control methods for optimizing charging waveforms and control methods combining models. The control method for optimizing charging waveforms can realize fast charging of batteries by optimizing constant current and constant voltage charging methods, step charging methods, pulse charging methods, and AC charging methods, but this method is a set of strategies for optimizing charging waveforms formulated offline for new batteries that have just left the factory, and does not fully consider the actual changes of batteries during actual use, resulting in low battery safety. The control method combining models includes combining equivalent circuit models, thermal models, electrochemical models, and combined models of the above models to realize fast charging of batteries through the above models, but this method has the following shortcomings: the aging difference of batteries during use is relatively large, it is difficult to accurately use a unified model to quickly charge batteries, and the cost of using model methods is relatively high. Summary of the invention

[0004] The embodiments of the present invention provide a battery charging method, system, vehicle and medium based on lithium plating detection, so as to improve the charging safety while realizing fast charging of the battery.

[0005] A battery charging method based on lithium plating detection, comprising:

[0006] After receiving the battery charging instruction, obtaining the battery charging strategy table;

[0007] Charging the battery according to the charging current in the battery charging strategy table, and performing at least one charging lithium deposition test on the battery during the battery charging process to obtain a first lithium deposition test result;

[0008] When the first lithium deposition detection result is that no lithium deposition occurs, the battery continues to be charged according to the charging current, and the battery continues to be charged with lithium deposition detection during the charging process of the battery, until the first lithium deposition detection result is that lithium deposition occurs, or until the battery is completely charged, and then the battery is stopped from being charged with lithium deposition detection;

[0009] When the first lithium deposition detection result indicates that lithium deposition occurs, the charging current in the battery charging strategy table is updated according to a preset first current reduction strategy, and the battery is continuously charged according to the updated charging current until the battery is completely charged.

[0010] A battery charging system based on lithium plating detection, comprising:

[0011] A charging strategy table acquisition module, used to acquire a battery charging strategy table after receiving a battery charging instruction;

[0012] A charging lithium deposition detection module, used for charging the battery according to the charging current in the battery charging strategy table, and performing at least one charging lithium deposition detection on the battery during the battery charging process to obtain a first lithium deposition detection result;

[0013] A first charging module, configured to, when the first lithium deposition detection result is that no lithium deposition occurs, continue to charge the battery according to the charging current, and continue to perform charging lithium deposition detection on the battery during the battery charging process until the battery is completely charged;

[0014] The second charging module is used to update the charging current in the battery charging strategy table according to a preset current reduction strategy when the first lithium deposition detection result is the occurrence of lithium deposition, and continue to charge the battery according to the updated charging current until the battery is completely charged.

[0015] A car comprises the above-mentioned battery charging system based on lithium plating detection.

[0016] The above-mentioned battery charging method, system and automobile based on lithium deposition detection, the method obtains a battery charging strategy table after receiving a battery charging instruction; charges the battery according to the charging current in the battery charging strategy table, and performs at least one charging lithium deposition detection on the battery during the battery charging process to obtain a first lithium deposition detection result; when the first lithium deposition detection result is that lithium deposition does not occur, continues to charge the battery according to the charging current, and continues to perform charging lithium deposition detection on the battery during the battery charging process until the first lithium deposition detection result is that lithium deposition occurs, or until the battery is completely charged, then stops performing charging lithium deposition detection on the battery; when the first lithium deposition detection result is that lithium deposition occurs, updates the charging current in the battery charging strategy table according to a preset first current reduction strategy, and continues to charge the battery according to the updated charging current until the battery is completely charged.

[0017] The present invention detects whether the battery has lithium deposition during the battery charging process, and when the battery has lithium deposition, reduces the current charging current of the battery according to a preset first current reduction strategy, thereby improving the safety of the battery charging process while fully ensuring the fast charging characteristics of the battery. In addition, the method in this embodiment can be applied to different types of batteries. It only needs to adjust the charging current in the battery charging strategy table of different types of batteries according to the first lithium deposition detection result. In addition, the method involves a small amount of calculation, which reduces the calculation complexity of the system and improves the operation rate of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0019] Figure 1 is a flow chart of a battery charging method based on lithium plating detection in one embodiment of the present invention;

[0020] Figure 2 is another flow chart of a battery charging method based on lithium plating detection in one embodiment of the present invention;

[0021] Figure 3 Schematic diagram of a voltage-time coordinate system in a method for detecting a lithium deposition state of a battery in one embodiment of the present invention;

[0022] Figure 4 is a flow chart of step S20 in a battery charging method based on lithium plating detection in one embodiment of the present invention;

[0023] Figure 5 It is a principle block diagram of a battery charging system based on lithium plating detection in one embodiment of the present invention;

[0024] Figure 6 is another principle block diagram of a battery charging system based on lithium plating detection in one embodiment of the present invention;

[0025] Figure 7 is a schematic diagram of a computer device in one embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In one embodiment, if Figure 1 As shown, a battery charging method based on lithium plating detection is provided, comprising the following steps:

[0028] S10: After receiving the battery charging instruction, obtain the battery charging strategy table.

[0029] Among them, the battery charging instruction is used to indicate that the power battery pack should be charged at this time. For example, the user finds that the current SOC (State Of Charge) value of the power battery pack is too low. At this time, the car is charged through a charging pile. At the moment of starting charging, a battery charging instruction is generated. The battery charging strategy table contains data related to battery charging, such as charging current, charging voltage, etc. The battery charging strategy table is obtained based on the fast charging strategy formulated by the battery factory. It is understandable that the charging current in the battery charging strategy table may be updated and adjusted during the battery charging process and / or after charging is completed, depending on whether lithium deposition occurs in the battery. Among them, lithium deposition refers to the phenomenon of metallic lithium deposition in the negative electrode of the battery.

[0030] S20: charging the battery according to the charging current in the battery charging strategy table, and performing at least one charging lithium deposition test on the battery during the battery charging process to obtain a first lithium deposition test result.

[0031] Among them, the charging lithium deposition detection refers to the process of detecting the lithium deposition phenomenon of the battery during the battery charging process, and the charging lithium deposition detection includes but is not limited to the following methods: three-electrode direct measurement method, coulomb efficiency measurement method and electrochemical impedance measurement method. The first lithium deposition detection result is obtained after the battery is charged and the lithium deposition detection result includes two results: the battery has lithium deposition phenomenon, and the battery has no lithium deposition phenomenon.

[0032] Specifically, after receiving the battery charging instruction, the battery charging strategy table is obtained to charge the battery according to the charging current in the battery charging strategy table, and the battery is subjected to at least one charging lithium deposition test during the battery charging process to obtain a first lithium deposition test result to determine whether the battery has lithium deposition during the charging process. If lithium deposition occurs during the charging process, the charging current of the battery during the current charging process should be reduced to suppress lithium deposition, thereby reducing the lithium deposition characteristic amount during the subsequent charging process. If lithium deposition does not occur during the charging process, the battery continues to be charged with the charging current during the current charging process, and continues to be subjected to charging lithium deposition test during the subsequent charging process until the battery is fully charged.

[0033] S30: When the first lithium deposition detection result is that lithium deposition does not occur, continue to charge the battery according to the charging current, and continue to perform charging lithium deposition detection on the battery during the battery charging process, until the first lithium deposition detection result is that lithium deposition occurs, or until the battery is completely charged, and then stop performing charging lithium deposition detection on the battery.

[0034] Specifically, after charging the battery according to the charging current in the battery charging strategy table, and performing charging lithium deposition detection on the battery during the battery charging process to obtain a first lithium deposition detection result, when the first lithium deposition detection result is that no lithium deposition occurs, the battery continues to be charged according to the charging current in the battery charging strategy table, and continues to perform charging lithium deposition detection on the battery during the battery charging process; when the first lithium deposition detection result obtained at any subsequent moment is that lithium deposition occurs, the charging lithium deposition detection on the battery is stopped, and the charging current in the battery charging strategy table is updated according to a preset first current reduction strategy, and the battery continues to be charged according to the updated charging current until the battery is completely charged; when the first detection results obtained by the subsequent charging lithium deposition detection on the battery do not show any lithium deposition, it indicates that there is no need to update the charging current in the battery charging strategy table, and after the battery is charged, the charging lithium deposition detection on the battery is stopped.

[0035] S40: When the first lithium deposition detection result indicates that lithium deposition occurs, the charging current in the battery charging strategy table is updated according to a preset first current reduction strategy, and the battery is continuously charged according to the updated charging current until the battery is completely charged.

[0036] Among them, the preset first current reduction strategy refers to a strategy for reducing the current charging current by a preset ratio. For example, the first current reduction strategy can be: reducing the charging current of the battery in the current charging process by a preset ratio, which can be 0.1% to 1% of the current charging current. For example, the preset ratio is 0.5% of the current charging current; in this way, when the charging current is 1A, the charging current can be reduced by 0.5%, that is, the charging current is reduced to 0.995A. Understandably, whether the battery has completed charging can be determined according to different situations. For example, it can be set that after the current SOC value of the battery reaches the preset SOC value, it is determined that the battery has completed charging; in another scenario, the battery can also be powered off in advance, such as a sudden power outage that causes the battery to be unable to continue charging or the charging is terminated in advance by manual operation (such as unplugging the charging plug from the charging pile). At this time, it can be considered that the battery has also completed charging.

[0037] Specifically, after charging the battery according to the charging current in the battery charging strategy table, and performing a charging lithium deposition test on the battery during the battery charging process to obtain a first lithium deposition test result, when the first lithium deposition test result is the occurrence of lithium deposition, according to the preset first current reduction strategy, the charging current of the battery in the current charging process is reduced (because when lithium deposition occurs in the battery, the lithium potential of the negative electrode of the battery is reduced to below 0V, if the current charging current is still maintained to charge the battery, the polarization phenomenon during the charging process will make it easier for the lithium potential of the negative electrode of the battery to be reduced to a smaller value, so it is necessary to reduce the current charging current of the battery), and the reduced charging current is updated to the battery charging strategy table; and the battery is continued to be charged according to the charging current in the updated battery charging strategy table (that is, the reduced charging current mentioned above) to reduce the probability of an increase in the amount of lithium deposition characteristics in the battery during subsequent charging processes until the battery is fully charged, thereby ensuring the safety of the battery during the charging process, that is, if lithium deposition is detected once in the battery during the charging process, it is not necessary to continue to perform charging and lithium deposition test on the battery.

[0038] In this embodiment, during the battery charging process, it is detected whether the battery has lithium deposition, and when the battery has lithium deposition, the current charging current of the battery is reduced according to the preset first current reduction strategy, thereby improving the safety of the battery charging process while ensuring that the battery exerts the fast charging characteristics of the battery under the premise of safety. In addition, the method in this embodiment can be applied to different types of lithium batteries. It only needs to adjust the charging current in the battery charging strategy table of different types of batteries according to the first lithium deposition detection result. In addition, the method involves a small amount of calculation, which reduces the calculation complexity of the system, thereby improving the operation rate of the system.

[0039] In one embodiment, after step S30 or S40, Figure 2As shown, after the battery is charged, the steps include:

[0040] S50: After the battery has completed charging and is in a static state, performing a static lithium deposition test on the battery to obtain a second lithium deposition test result.

[0041] Among them, the static state refers to a state where no other operations (such as discharging, charging, etc.) are performed on the battery. Static lithium deposition detection refers to a method of performing lithium deposition detection on the battery after the battery is fully charged. The static lithium deposition detection includes but is not limited to the following methods: voltage static method, nonlinear frequency response method, and voltage relaxation method. The second lithium deposition detection result is obtained after the battery is subjected to a static lithium deposition detection after the battery is fully charged. The second lithium deposition detection result includes two results, namely, the occurrence of lithium deposition in the battery and the absence of lithium deposition in the battery. When the second lithium deposition detection result is that the battery has lithium deposition, the second lithium deposition detection result can also characterize the lithium deposition characterization quantity of the battery.

[0042] Specifically, the battery continues to be charged according to the updated charging current, and the battery continues to be tested for charging lithium deposition during the battery charging process until the battery is completely charged, and the charged battery is placed in a static state to perform a static lithium deposition test on the battery to obtain a second lithium deposition test result.

[0043] In a specific embodiment, in step S50, that is, after the battery is charged and in a static state, a static lithium deposition test is performed on the battery to obtain a second lithium deposition test result, which includes the following steps:

[0044] After the battery has been charged and is in a static state, the voltage of the battery is collected regularly according to a preset time interval, and the collected voltage is associated with the collection time of the voltage and stored as voltage data.

[0045] Among them, the battery in this step refers to the battery that is waiting for static lithium deposition detection after charging is completed. Among them, lithium deposition of the battery during charging means that a portion of lithium metal is deposited at the negative electrode of the battery during charging. The preset time interval can be determined according to the actual detection requirements (such as the type of battery to be detected, etc.). For example, the preset time interval can be every 5 seconds. Or every 10 seconds, etc. The acquisition time refers to the time point corresponding to the voltage of the battery collected according to the preset time interval. The voltage data contains each set of voltages and the corresponding acquisition time.

[0046] A time-differential voltage curve is constructed in a voltage-time coordinate system according to the voltage data.

[0047] The time differential voltage curve represents the curve of the first-order derivative relationship of the battery with the change of voltage. The first-order derivative relationship is calculated based on the acquisition time and voltage. The voltage-time coordinate system is as follows: Figure 3 The coordinate system shown in the figure has a horizontal axis representing the voltage of the collected battery, and a vertical axis representing the time corresponding to the voltage of the collected battery. Among them, L1 represents the time differential voltage curve; L2 represents the curve of the voltage of the collected battery changing with the collection time. Specifically, after the voltage of the battery is collected regularly according to a preset time interval, and the collected voltage is associated with the collection time of the voltage and stored as voltage data, the time differential voltage is used to obtain the first-order derivative relationship corresponding to the voltage data according to the voltage data, and then the time differential voltage curve is determined.

[0048] Optionally, in this step, determining the time differential voltage curve according to the voltage data includes: generating the time differential voltage curve according to the voltage data and a preset first-order derivative relationship. The preset first-order derivative relationship is calculated based on the voltage of each group of collected batteries and the collection time, and the preset first-order derivative relationship is dt / dU.

[0049] Specifically, after the voltage of the battery is collected at a preset time interval and the collected voltage is associated with the collection time of the voltage and stored as voltage data, a preset first-order derivative relationship is obtained according to each group of voltages in the voltage data and the corresponding collection time; since each collected voltage has a corresponding first-order derivative relationship value, a time differential voltage curve is determined.

[0050] A second lithium deposition detection result is obtained according to the time differential voltage curve and a preset peak finding and identification algorithm.

[0051] The preset peak identification algorithm is used to find the characteristic peak voltage corresponding to the characteristic peak when the characteristic peak appears in the time differential voltage curve. The characteristic peak voltage is used to characterize the occurrence of lithium deposition in the battery during charging. In this embodiment, the peak identification algorithm can set a search area in the voltage-time coordinate system (for example, it can be divided according to time). If the maximum value is found in the area (that is, as shown in FIG. Figure 3 As shown, the time differential voltage curve L1 shows a point where the curve first rises and then declines, that is, a characteristic peak phenomenon occurs), and the point corresponding to the maximum value is determined as the characteristic peak point.

[0052] Specifically, after constructing a time differential voltage curve in a voltage-time coordinate system according to the voltage data, a preset peak-finding identification algorithm is used to find out whether a characteristic peak voltage exists in the time differential voltage curve. If a characteristic peak voltage is found in the time differential voltage curve, it is characterized that the second lithium deposition detection result is that lithium deposition occurs in the battery after charging is completed; if no characteristic peak voltage is found in the time differential voltage curve, it is characterized that the second lithium deposition detection result is that no lithium deposition occurs in the battery after charging is completed.

[0053] S60: When the second lithium deposition detection result indicates that lithium deposition occurs, updating the charging current in the battery charging strategy table according to a preset second current reduction strategy.

[0054] Among them, the second current reduction strategy refers to: according to the lithium plating characteristic amount after the battery is charged and the lithium plating standard corresponding to the battery, determine the reduction ratio of the charging current that needs to be reduced, and then update and reduce the charging current in the battery charging strategy table according to the reduction ratio. For example, the reduction ratio is 1% of the current charging current; in this way, when the charging current in the battery charging strategy table is 1A, the charging current can be reduced by 1%, that is, the charging current is reduced to 0.99A. It can be understood that in the present invention, the preset ratio of the first current reduction strategy and the reduction ratio in the second current reduction strategy may be the same or different.

[0055] Specifically, after performing a static lithium deposition test on the battery and obtaining a second lithium deposition test result, when the second lithium deposition test result is that lithium deposition occurs, the lithium deposition characterization quantity of the battery is further confirmed to obtain a lithium deposition characterization quantity corresponding to the lithium deposition phenomenon after the battery is charged; and then the charging current in the battery charging strategy table is updated according to the lithium deposition characterization quantity and a preset second current reduction strategy.

[0056] Optionally, in step S60, that is, when the second lithium deposition detection result is that lithium deposition occurs, updating the charging current in the battery charging strategy table according to a preset second current reduction strategy includes the following steps:

[0057] The characteristic peak voltage in the time differential voltage curve is identified by the preset peak identification algorithm, and after the characteristic peak voltage is determined, the corresponding stable voltage when the time differential voltage curve reaches a preset stability standard is recorded.

[0058] The preset stability standard refers to that the curve value of the time differential voltage curve meets the following requirement: within the range of -100 to -∞, it approaches a stable and unchanged state. In this embodiment, when the change of the time differential voltage curve with the voltage is particularly small over a long period of time (the curve approaches a straight line, and the curve value of the time differential voltage curve approaches a stable and unchanged state), the voltage value corresponding to the time differential voltage curve at the beginning of the state is recorded as the stable voltage.

[0059] Specifically, after determining the time differential voltage curve according to the voltage data, the characteristic peak voltage in the time differential voltage curve is identified by the peak recognition algorithm, which indicates that lithium deposition has occurred in the battery during the charging process, that is, it is determined that the battery is in a lithium deposition state during the charging process. At this time, it is necessary to record the stable voltage corresponding to the time differential voltage curve when it reaches a preset stability standard after determining the characteristic peak voltage.

[0060] The area of ​​the first region and the area of ​​the second region are determined in the voltage-time coordinate system according to the characteristic peak voltage, the stable voltage and the time differential voltage curve.

[0061] Specifically, after identifying the characteristic peak voltage in the time differential voltage curve by a peak identification algorithm, and recording the stable voltage corresponding to when the time differential voltage curve reaches a preset stability standard after the characteristic peak voltage appears, the charging voltage at the end of charging of the battery is obtained, wherein the starting point of the time differential voltage curve corresponds to the charging voltage; determining a reference horizontal axis and a first reference vertical axis; the reference horizontal axis refers to the horizontal axis corresponding to the starting point in the voltage-time coordinate system, and the first reference vertical axis refers to the vertical axis corresponding to the characteristic peak voltage in the voltage-time coordinate system; calculating the area of ​​a first region corresponding to the region enclosed by the reference horizontal axis, the first reference vertical axis and the time differential voltage curve. Figure 3 In the voltage-time coordinate system shown, U1 is the starting point in the time differential voltage curve corresponding to the charging voltage; U2 refers to the point in the time differential voltage curve corresponding to the characteristic peak voltage; U3 refers to the point in the time differential voltage curve corresponding to the stable voltage; L3 is the reference horizontal axis; L4 is the first reference vertical axis; L5 is the second reference vertical axis.

[0062] Further, determine a second reference vertical axis; the second reference vertical axis refers to the vertical axis corresponding to the stable voltage in the voltage-time coordinate system; calculate the area of ​​a second region corresponding to the region enclosed by the reference horizontal axis, the first reference vertical axis, the second reference vertical axis and the time differential voltage curve.

[0063] According to the area of ​​the first region and the area of ​​the second region, a lithium plating characterization value of the battery is determined; and according to the lithium plating characterization value and a preset battery lithium plating standard, the charging current in the battery charging strategy table is updated.

[0064] The lithium deposition characteristic quantity characterizes the degree of lithium deposition of the battery during charging. The preset battery lithium deposition standard refers to the lithium deposition standard obtained by testing the battery before leaving the factory, that is, each battery has a corresponding preset battery lithium deposition standard.

[0065] Specifically, after obtaining the area of ​​the first region according to the characteristic peak voltage and the time differential voltage curve, and obtaining the area of ​​the second region according to the characteristic peak voltage, the stable voltage and the time differential voltage curve, the lithium plating characterization value of the battery is determined according to the area of ​​the first region and the area of ​​the second region, and then the severity of the lithium plating occurring in the battery during the charging process can be determined by the lithium plating standard in the factory specification book of the battery (that is, the preset battery lithium plating standard); if the lithium plating characterization value exceeds the corresponding lithium plating standard of the battery, a second current reduction strategy needs to be adopted to reduce the current charging current in the battery charging strategy table, that is, according to the difference between the lithium plating characterization value after the battery is charged and the lithium plating standard, the reduction ratio of the charging current needs to be determined, and then the charging current in the battery charging strategy table is updated and reduced according to the reduction ratio. For example, after the battery is charged, the lithium precipitation characterization amount exceeds the lithium precipitation standard, and the reduction ratio is preset to 1% of the current charging current. If the charging current in the battery charging strategy table is 1A, at this time, the charging current can be reduced by 1%, that is, the charging current is reduced to 0.99A. In this way, the battery can be charged with the reduced charging current when the battery is charged next time, thereby reducing the lithium precipitation characterization amount of the battery, thereby achieving the effect of protecting the battery. It can be understood that if the lithium precipitation characterization amount seriously exceeds the lithium precipitation standard corresponding to the battery (for example, the excess amount is greater than or equal to the preset percentage of the lithium precipitation standard, illustratively, the preset percentage can be 40%; but the preset percentage can also be set to other percentages other than 40% according to demand; it can be understood that when the excess amount is less than the preset percentage, the current charging current in the battery charging strategy table can be reduced according to the above-mentioned second current reduction strategy), it indicates that the battery should be returned to the factory for inspection to avoid safety accidents caused by excessive lithium precipitation characterization of the battery.

[0066] It should be noted that the time point when the characteristic peak voltage appears in the time differential voltage curve is the time point when the active lithium is completely embedded in the graphite, that is, the physical meaning of the area of ​​the first region refers to the time required for the "active lithium" precipitated from the battery during the charging process to be embedded from the outside of the graphite to the inside. The area of ​​the second region corresponding to the characteristic peak voltage to the stable voltage indicates that the lithium ion concentration is basically balanced from the diaphragm to the copper foil; therefore, lithium ions are more inclined to diffuse from the outside of the graphite particles to the inside of the particles, so that the lithium ions are evenly distributed throughout the graphite particles.

[0067] Specifically, since the physical meaning of the area of ​​the first region refers to the time required for the "active lithium" released by the battery during charging to be embedded from the outside of the graphite to the inside, it is inaccurate to simply use the area of ​​the first region to characterize the total lithium deposition amount of the battery, because the time experienced is related to the lithium deposition amount and the lithium insertion rate of graphite, and the lithium insertion rate of graphite is related to temperature, so at the same temperature, the time can be used to characterize the lithium deposition amount.

[0068] Therefore, the present invention uses the reciprocal of the area of ​​the second region to characterize the lithium deposition rate of the battery. However, during the collection time of the first region area, part of the "live lithium" that has entered the negative electrode has begun to be in equilibrium during the process of other "live lithium" being embedded in the negative electrode, and the time for some "live lithium" to be in equilibrium in the negative electrode overlaps with the collection time of the first region area. However, before reaching the characteristic peak voltage, the "live lithium" entering the negative electrode is the main factor. After reaching the characteristic peak voltage, the concentration difference of lithium ions in the negative electrode graphite particles is the largest. All the reciprocal of the time from the "live lithium" being completely embedded in the negative electrode to the negative electrode graphite particles reaching the final equilibrium time (that is, the second region area) is used to characterize the graphite lithium insertion rate (that is, the lithium deposition rate).

[0069] Further, according to the above description, the area of ​​the first region can be recorded as the lithium deposition time of the battery; the reciprocal of the area of ​​the second region can be recorded as the lithium deposition rate of the battery; and then the product of the reciprocal of the area of ​​the second region and the area of ​​the first region can be recorded as the lithium deposition characterization quantity of the battery, that is, the product of the lithium deposition time and the lithium deposition rate can be recorded as the lithium deposition characterization quantity of the battery.

[0070] In another specific embodiment, after performing a static lithium deposition test on the battery to obtain a second lithium deposition test result, the method further includes:

[0071] When the second lithium deposition detection result is that no lithium deposition occurs, that is, after the battery is fully charged, no lithium deposition occurs, it indicates that in the next charging process of the battery, charging the battery with the current charging current in the battery charging strategy table will not increase the lithium deposition characterization amount of the battery, and thus the charging current in the battery charging strategy table will not be updated. Optionally, when the peak-finding recognition algorithm fails to identify the characteristic peak voltage in the time differential voltage curve, it can be indicated that no lithium deposition occurs in the battery during the charging process. Specifically, since the characteristic peak voltage is used in the physical sense to characterize the occurrence of lithium deposition in the battery during the charging process in the present invention, after determining the time differential voltage curve according to the voltage data, when the peak-finding recognition algorithm fails to identify the characteristic peak voltage in the time differential voltage curve, it indicates that no lithium deposition occurs in the battery during the charging process.

[0072] In this embodiment, after the battery is completely charged, a static lithium deposition test is performed on the battery to determine whether lithium deposition occurs in the battery after charging is completed, and when lithium deposition occurs in the battery, the current charging current of the battery is reduced according to a preset second current reduction strategy, thereby improving the safety of the battery charging process and ensuring that the battery avoids lithium deposition when charging with the updated charging current in the battery charging strategy table when the battery receives a charging instruction next time, thereby further improving the safety of the battery.

[0073] In one embodiment, in step S20, Figure 3 As shown, that is, during the battery charging process, the battery is subjected to at least one charging lithium deposition test to obtain a first lithium deposition test result, including:

[0074] S201: Obtaining a first electrochemical impedance and a second electrochemical impedance of the battery at a preset frequency according to a preset SOC change; the first SOC value corresponding to the first electrochemical impedance and the second SOC value corresponding to the second electrochemical impedance are both greater than a preset SOC threshold; and the difference between the second SOC value and the first SOC value is equal to a preset SOC change.

[0075] Among them, the first SOC value refers to the ratio of the current remaining capacity of the battery to the capacity of the battery in a fully charged state. Optionally, the preset SOC threshold can be determined according to the type of battery and the charging demand. Exemplarily, the preset SOC threshold can be 70%, 75%, etc. Electrochemical impedance refers to the ratio of the AC voltage to the current signal of the battery during the charging process. The electrochemical impedance corresponds to the SOC value of the battery and the preset frequency (such as the first electrochemical impedance corresponds to the first SOC value and the preset frequency, and the second electrochemical impedance corresponds to the second SOC value and the preset frequency). Exemplarily, the preset frequency can be any value selected from the frequency range of 0.01Hz to 10Hz. The preset frequency can be determined according to the type of battery, that is, the preset frequencies corresponding to different types of batteries (such as power batteries, 3C batteries) are different.

[0076] Optionally, the preset SOC change can be set according to demand, such as 5%, 10%, etc.; assuming that the preset SOC change is 5%, the preset SOC threshold is 70%; then the first SOC value can be 75%, and the second SOC value can be 80%.

[0077] Specifically, in this embodiment, the electrochemical impedance measurement method is used to detect the lithium deposition of the battery. After charging the battery according to the charging current in the battery charging strategy table, the first electrochemical impedance and the second electrochemical impedance of the battery at a preset frequency are obtained according to the preset SOC change.

[0078] In a specific embodiment, assuming that only one charging lithium deposition test is performed on the battery during the charging process, and the first lithium deposition test result is that the battery exhibits lithium deposition during the charging process, then there is only one set of corresponding first electrochemical impedance and second electrochemical impedance in this charging lithium deposition test, that is, the first lithium deposition test result determined based on this set of first electrochemical impedance and second electrochemical impedance is that the battery exhibits lithium deposition during the charging process.

[0079] In another specific embodiment, assuming that the battery is subjected to multiple charging lithium deposition tests during the charging process, and the result of the last lithium deposition test is that the battery has lithium deposition during the charging process, then there are multiple groups of corresponding first electrochemical impedances and second electrochemical impedances in the charging lithium deposition test. When the result of the first lithium deposition test is that the battery has no lithium deposition during the charging process, the second electrochemical impedance at this time can be used as the new first electrochemical impedance for the next charging lithium deposition test, and the new second electrochemical impedance corresponding to it is obtained according to the preset SOC change, and the new first lithium deposition test result is determined according to the new first electrochemical impedance and the new second electrochemical impedance. The difference between the second SOC value corresponding to each group and the first SOC value is equal to the preset SOC change.

[0080] S202: Determine a first lithium plating detection result of the battery at the second detection time according to the first electrochemical impedance and the second electrochemical impedance.

[0081] Specifically, after obtaining the second electrochemical impedance of the battery at a preset frequency at the second detection time, the first electrochemical impedance and the second electrochemical impedance are compared, and then the first lithium plating detection result of the battery at the second detection time is determined according to the result obtained after the comparison.

[0082] Further, after comparing the first electrochemical impedance and the second electrochemical impedance, when the second electrochemical impedance is less than the first electrochemical impedance, it is determined that the first lithium deposition detection result at the second detection time is the occurrence of lithium deposition.

[0083] After comparing the first electrochemical impedance and the second electrochemical impedance, when the second electrochemical impedance is greater than or equal to the first electrochemical impedance, it is determined that the first lithium deposition detection result at the second detection time is that no lithium deposition phenomenon occurs.

[0084] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0085] In one embodiment, if Figure 5 As shown, a battery charging system based on lithium plating detection is provided, comprising the following modules:

[0086] A charging strategy table acquisition module 10 is used to acquire a battery charging strategy table after receiving a battery charging instruction;

[0087] A charging lithium deposition detection module 20, configured to charge the battery according to the charging current in the battery charging strategy table, and perform at least one charging lithium deposition detection on the battery during the battery charging process to obtain a first lithium deposition detection result;

[0088] A first charging module 30 is used for, when the first lithium deposition detection result is that no lithium deposition occurs, continuing to charge the battery according to the charging current, and continuing to perform charging lithium deposition detection on the battery during the battery charging process, until the first lithium deposition detection result is that lithium deposition occurs, or until the battery is completely charged, then stopping the charging lithium deposition detection on the battery;

[0089] The second charging module 40 is used to update the charging current in the battery charging strategy table according to a preset current reduction strategy when the first lithium deposition detection result indicates that lithium deposition has occurred, and to continue charging the battery according to the updated charging current until the battery is completely charged.

[0090] Alternatively, if Figure 6 As shown, the battery charging system based on lithium plating detection also includes the following modules:

[0091] A static lithium deposition detection module 50 is used to perform a static lithium deposition detection on the battery after the battery has completed charging and is in a static state, to obtain a second lithium deposition detection result;

[0092] The charging current updating module 60 is used to update the charging current in the battery charging strategy table according to a preset second current reduction strategy when the second lithium deposition detection result indicates that lithium deposition occurs.

[0093] Optionally, the static lithium deposition detection module 50 includes the following units:

[0094] A voltage acquisition unit, used for acquiring the voltage of the battery at a preset time interval after the battery has been charged and is in a static state, and storing the acquired voltage in association with the acquisition time of the voltage as voltage data;

[0095] A curve construction unit, used for constructing a time differential voltage curve in a voltage-time coordinate system according to the voltage data;

[0096] The peak finding and identifying unit is used to obtain a second lithium deposition detection result according to the time differential voltage curve and a preset peak finding and identifying algorithm.

[0097] Optionally, the charging current updating module 60 includes the following units:

[0098] A voltage recording unit, used to identify a characteristic peak voltage in the time differential voltage curve by using the preset peak identification algorithm, and after determining the characteristic peak voltage, record a stable voltage corresponding to when the time differential voltage curve reaches a preset stability standard;

[0099] an area determination unit, configured to determine the area of ​​the first region and the area of ​​the second region in the voltage-time coordinate system according to the characteristic peak voltage, the stable voltage and the time differential voltage curve;

[0100] a lithium deposition characterization amount determining unit, configured to determine the lithium deposition characterization amount of the battery according to the area of ​​the first region and the area of ​​the second region;

[0101] A current updating unit is used to update the charging current in the battery charging strategy table according to the lithium deposition characterization value and a preset battery lithium deposition standard.

[0102] Optionally, the charging lithium deposition detection module 20 includes the following units:

[0103] an electrochemical impedance acquisition unit, configured to acquire a first electrochemical impedance and a second electrochemical impedance of the battery at a preset frequency according to a preset SOC change; the first SOC value corresponding to the first electrochemical impedance and the second SOC value corresponding to the second electrochemical impedance are both greater than a preset SOC threshold; and a difference between the second SOC value and the first SOC value is equal to a preset SOC change;

[0104] A lithium deposition detection result acquisition unit is used to acquire the first lithium deposition detection result according to the first electrochemical impedance and the second electrochemical impedance.

[0105] Optionally, the lithium deposition detection result acquisition unit includes the following subunits:

[0106] a first impedance comparison unit, configured to determine, when the second electrochemical impedance is less than the first electrochemical impedance, that the first lithium deposition detection result is the occurrence of lithium deposition;

[0107] The second impedance comparison unit is used to determine that the first lithium deposition detection result is that no lithium deposition phenomenon occurs when the second electrochemical impedance is greater than or equal to the first electrochemical impedance.

[0108] In one embodiment, a car is provided, comprising the above-mentioned battery charging system based on lithium plating detection.

[0109] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 7 As shown. The computer device includes a processor, a memory, a network interface and a database connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a battery charging method based on lithium plating detection is implemented.

[0110] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the battery charging method based on lithium plating detection in the above embodiment is implemented.

[0111] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the battery charging method based on lithium plating detection in the embodiment is implemented.

[0112] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0113] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0114] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A battery charging method based on lithium plating detection, characterized in that: include: After receiving the battery charging instruction, obtaining the battery charging strategy table; Charging the battery according to the charging current in the battery charging strategy table, and performing at least one charging lithium deposition test on the battery during the battery charging process to obtain a first lithium deposition test result; When the first lithium deposition detection result is that no lithium deposition occurs, the battery continues to be charged according to the charging current, and the battery continues to be charged with lithium deposition detection during the charging process of the battery, until the first lithium deposition detection result is that lithium deposition occurs, or until the battery is completely charged, and then the battery is stopped from being charged with lithium deposition detection; When the first lithium deposition detection result indicates that lithium deposition occurs, the charging current in the battery charging strategy table is updated according to a preset first current reduction strategy, and the battery is continuously charged according to the updated charging current until the battery is completely charged; After the battery is fully charged, the method includes: After the battery is charged and in a static state, performing a static lithium deposition test on the battery to obtain a second lithium deposition test result; When the second lithium deposition detection result indicates that lithium deposition occurs, updating the charging current in the battery charging strategy table according to a preset second current reduction strategy; After the battery is charged and in a static state, performing a static lithium deposition test on the battery to obtain a second lithium deposition test result includes: After the battery is fully charged and in a static state, the voltage of the battery is collected regularly according to a preset time interval, and the collected voltage is associated with the collection time of the voltage and stored as voltage data; constructing a time-differential voltage curve in a voltage-time coordinate system according to the voltage data; Obtaining a second lithium deposition detection result according to the time differential voltage curve and a preset peak-finding recognition algorithm; The step of obtaining a second lithium deposition detection result according to the time differential voltage curve and a preset peak identification algorithm includes: By using a preset peak-finding recognition algorithm, a characteristic peak voltage is searched in the time differential voltage curve. If a characteristic peak voltage is found in the time differential voltage curve, it is characterized that the second lithium deposition detection result is that lithium deposition occurs in the battery after charging is completed; if no characteristic peak voltage is found in the time differential voltage curve, it is characterized that the second lithium deposition detection result is that no lithium deposition occurs in the battery after charging is completed; The updating of the charging current in the battery charging strategy table according to the preset second current reduction strategy includes: Identifying a characteristic peak voltage in the time differential voltage curve by using the preset peak identification algorithm, and after determining the characteristic peak voltage, recording a stable voltage corresponding to when the time differential voltage curve reaches a preset stability standard; According to the characteristic peak voltage, the stable voltage and the time differential voltage curve, the first area and the second area are determined in the voltage-time coordinate system; the first area is an area enclosed by a reference horizontal axis, a first reference vertical axis and the time differential voltage curve; the reference horizontal axis refers to the horizontal axis corresponding to the starting point of the time differential voltage curve in the voltage-time coordinate system, and the first reference vertical axis refers to the vertical axis corresponding to the characteristic peak voltage in the voltage-time coordinate system; the second area is an area enclosed by the reference horizontal axis, the first reference vertical axis, the second reference vertical axis and the time differential voltage curve; the second reference vertical axis refers to the vertical axis corresponding to the stable voltage in the voltage-time coordinate system; Determining a lithium deposition characteristic value of the battery according to the area of ​​the first region and the area of ​​the second region; The charging current in the battery charging strategy table is updated according to the lithium deposition characteristic value and a preset battery lithium deposition standard.

2. The battery charging method based on lithium plating detection according to claim 1, characterized in that: The step of performing at least one charging lithium deposition test on the battery during the battery charging process to obtain a first lithium deposition test result includes: The first electrochemical impedance and the second electrochemical impedance of the battery at a preset frequency are obtained according to a preset SOC change; a first SOC value corresponding to the first electrochemical impedance and a second SOC value corresponding to the second electrochemical impedance are both greater than a preset SOC threshold; a difference between the second SOC value and the first SOC value is equal to a preset SOC change; and the first SOC value corresponding to the first electrochemical impedance is less than the second SOC value corresponding to the second electrochemical impedance; The first lithium deposition detection result is obtained according to the first electrochemical impedance and the second electrochemical impedance.

3. The battery charging method based on lithium plating detection according to claim 2, characterized in that: The determining a first lithium deposition detection result of the battery according to the first electrochemical impedance and the second electrochemical impedance includes: When the second electrochemical impedance is less than the first electrochemical impedance, determining that the first lithium deposition detection result is that lithium deposition occurs; When the second electrochemical impedance is greater than or equal to the first electrochemical impedance, it is determined that the first lithium deposition detection result is that no lithium deposition phenomenon occurs.

4. A battery charging system based on lithium plating detection, characterized in that: The battery charging system based on lithium plating detection is used to execute the battery charging method based on lithium plating detection as claimed in any one of claims 1 to 3, comprising: A charging strategy table acquisition module, used to acquire a battery charging strategy table after receiving a battery charging instruction; A charging lithium deposition detection module, used for charging the battery according to the charging current in the battery charging strategy table, and performing at least one charging lithium deposition detection on the battery during the battery charging process to obtain a first lithium deposition detection result; a first charging module, configured to, when the first lithium deposition detection result is that no lithium deposition occurs, continue to charge the battery according to the charging current, and continue to perform charging lithium deposition detection on the battery during the battery charging process, until the first lithium deposition detection result is that lithium deposition occurs, or until the battery is completely charged, then stop performing charging lithium deposition detection on the battery; The second charging module is used to update the charging current in the battery charging strategy table according to a preset current reduction strategy when the first lithium deposition detection result is the occurrence of lithium deposition, and continue to charge the battery according to the updated charging current until the battery is completely charged.

5. The battery charging system based on lithium plating detection as claimed in claim 4, characterized in that: The battery charging system based on lithium plating detection also includes: A static lithium deposition detection module, used for performing a static lithium deposition detection on the battery after the battery has completed charging and is in a static state, to obtain a second lithium deposition detection result; A charging current updating module is used to update the charging current in the battery charging strategy table according to a preset second current reduction strategy when the second lithium deposition detection result indicates that lithium deposition occurs.

6. A car, characterized in that: It comprises a battery charging system based on lithium plating detection as described in any one of claims 4 to 5.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the battery charging method based on lithium plating detection as claimed in any one of claims 1 to 3 is implemented.

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