Method, device and system for determining safety boundary of battery charging strategy

Abstract

The present application discloses a method, device and system for determining the safety boundary of a battery charging strategy, which relates to the field of automobile technology. The method for determining the safety boundary of the battery charging strategy includes: obtaining a dynamically adjusted charging strategy; the charging strategy can be dynamically adjusted based on the detection result of whether the battery has lithium deposition during the charging process; after charging the battery using the adjusted charging strategy respectively, obtaining the voltage information of the battery in the static stage; based on the voltage information of the battery in the static stage, detecting whether the battery has lithium deposition during the charging process; and determining the safety boundary of the battery charging strategy based on the detection result; wherein the safety boundary of the charging strategy includes at least one of the following: an upper limit current without lithium deposition; a lower limit temperature without lithium deposition; an upper limit voltage without lithium deposition. The scheme of the present application realizes the accurate measurement of the safety boundary of the battery charging strategy.

Description

Technical Field

[0001] The present application relates to the field of automobile technology, and in particular to a method, device and system for determining a safety boundary of a battery charging strategy. Background Art

[0002] In recent years, my country's electric vehicle industry has developed rapidly. With the growth of the market, the safety issues of electric vehicles have become increasingly prominent, especially in recent years, electric vehicle fires have become more and more frequent. The essence of electric vehicle fires is battery thermal runaway. Accident statistics show that during the charging process, if the charging strategy is not appropriate, it will cause lithium deposition in the battery. After lithium deposition, the safety of the battery is greatly reduced, making the battery more likely to trigger thermal runaway. Therefore, during charging and the short-term static stage after charging is a high-incidence period for battery thermal runaway.

[0003] Currently, lithium-ion batteries are widely used as power batteries for electric vehicles. In order to significantly shorten the charging time and further improve the convenience of charging, the main measure currently taken is to increase the current of the battery during the charging process. However, since the negative electrode materials of commercial lithium-ion batteries mostly use carbon materials mainly composed of graphite, which have a low potential for lithium, lithium-ion batteries are prone to precipitating metallic lithium at the negative electrode during the charging process. After the battery precipitates lithium, the presence of active lithium will cause the thermal stability of the negative electrode material to decrease, the starting temperature of the battery's self-heat generation to decrease, and thermal runaway will be more likely to occur. How to ensure the safety of the charging process while increasing the battery's charging rate is the primary consideration when charging the battery.

[0004] The existing methods for formulating battery charging strategies are mainly as follows: when formulating charging strategies, a special "three-electrode battery" system is prepared according to the characteristics of different batteries to monitor the potential of the negative electrode in real time, so that it is always kept above the lithium deposition potential. If the negative electrode potential does not exceed the battery lithium deposition potential, the charging rate is further increased. However, this strategy requires the preparation of special battery devices in advance, and the preparation process of special battery devices has certain technical requirements. In addition, although it is theoretically feasible to use the negative electrode potential to observe whether lithium deposition occurs, there is a certain "hysteresis" phenomenon between the actual lithium deposition situation inside the battery and the negative electrode potential, and there is a certain error in the measurement results. Summary of the invention

[0005] The purpose of the present application is to provide a method, device and system for determining a battery charging strategy safety boundary, thereby solving the problem of low measurement accuracy of the battery charging strategy safety boundary in the prior art.

[0006] In order to achieve the above object, the present application provides a method for determining a safety boundary of a battery charging strategy, comprising:

[0007] Obtaining a dynamically adjusted charging strategy; the charging strategy can be dynamically adjusted based on a detection result of whether lithium deposition occurs during the charging process of the battery;

[0008] After charging the batteries using the adjusted charging strategies respectively, voltage information of the batteries in a static stage is obtained;

[0009] Detecting whether lithium deposition occurs during charging of the battery according to voltage information of the battery at rest;

[0010] Determine the safety margin of the charging strategy of the battery according to the detection result; wherein the safety margin of the charging strategy includes at least one of the following:

[0011] The upper limit current without lithium deposition;

[0012] The lower limit temperature for no lithium precipitation;

[0013] The upper limit voltage without lithium deposition.

[0014] Optionally, the charging strategy includes: at least one of a charging cut-off voltage and a charging temperature:

[0015] The charging strategy is dynamically adjusted based on the detection result of whether lithium deposition occurs during the charging process of the battery, including at least one of the following:

[0016] When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the first charging strategy, reducing the charging temperature in the first charging strategy to obtain an adjusted charging strategy;

[0017] When it is detected that no lithium deposition occurs during the process of charging the battery using the first charging strategy, the charging cut-off voltage in the first charging strategy is increased to obtain an adjusted charging strategy.

[0018] Optionally, determining a safety boundary of the charging strategy of the battery according to the detection result includes:

[0019] When the detection result corresponding to the adjusted charging strategy is the presence of lithium deposition, at least one of the charging cut-off voltage and the charging temperature included in the charging strategy used in the previous charging process adjacent to the charging process with lithium deposition is determined as the safety boundary of the charging strategy.

[0020] Optionally, the charging strategy includes: charging current;

[0021] The charging strategy is dynamically adjusted based on the detection result of whether lithium deposition occurs during the charging process of the battery, including at least one of the following:

[0022] When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the second charging strategy, and the second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is increased by a first preset adjustment value to obtain an adjusted third charging strategy; the first charging current is the charging current in the charging strategy used in the previous charging process adjacent to the process of charging the battery using the second charging strategy;

[0023] When it is detected that lithium deposition occurs during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fourth charging strategy; the second preset adjustment value is less than the first preset adjustment value;

[0024] When it is detected that lithium deposition occurs during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is less than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fifth charging strategy.

[0025] Optionally, the method further comprises:

[0026] When the fifth charging current corresponding to the adjusted fifth charging strategy is the preset current, the adjustment of the charging strategy based on the detection result of whether lithium deposition occurs during the charging process of the battery is stopped.

[0027] Optionally, determining the safety boundary of the charging strategy of the battery according to the detection result includes at least one of the following:

[0028] When it is detected that no lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the charging current corresponding to the fourth charging strategy is the no-lithium deposition upper limit current;

[0029] When it is detected that lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the difference between the charging current corresponding to the fourth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current;

[0030] When it is detected that lithium deposition occurs during charging of the battery using the fifth charging strategy and the charging current corresponding to the fifth charging strategy is a preset current, determining that the difference between the charging current corresponding to the fifth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current;

[0031] When it is detected that no lithium deposition occurs during the charging of the battery using the fifth charging strategy, the charging current corresponding to the fifth charging strategy is determined to be the no-lithium deposition upper limit current.

[0032] Optionally, detecting whether lithium deposition occurs during charging of the battery according to voltage information of the battery in a static stage includes:

[0033] When the voltage information of the battery in the static stage is a voltage curve and the voltage curve has a minimum value, it is determined that lithium deposition occurs in the battery during the charging process.

[0034] The embodiment of the present application also provides a device for determining a battery charging strategy safety boundary, including:

[0035] A first acquisition module is used to acquire a dynamically adjusted charging strategy; the charging strategy can be dynamically adjusted based on a detection result of whether lithium deposition occurs during the charging process of the battery;

[0036] A second acquisition module is used to acquire voltage information of the battery in a static stage after charging the battery using the adjusted charging strategy;

[0037] A detection module, used to detect whether there is lithium deposition in the battery during charging according to the voltage information of the battery in the static stage;

[0038] A determination module is used to determine the safety boundary of the charging strategy of the battery according to the detection result; wherein the safety boundary of the charging strategy includes at least one of the following:

[0039] The upper limit current without lithium deposition;

[0040] The lower limit temperature for no lithium precipitation;

[0041] The upper limit voltage without lithium deposition.

[0042] An embodiment of the present application also provides a system for determining a battery charging strategy safety boundary, comprising: a processor, a memory, and a program stored in the memory and executable on the processor, wherein the program, when executed by the processor, implements the steps of the method for determining a battery charging strategy safety boundary described above.

[0043] An embodiment of the present application further provides a readable storage medium, on which a program is stored. When the program is executed by a processor, the steps of the method for determining the safety boundary of the battery charging strategy as described above are implemented.

[0044] The above technical solution of the present application has at least the following beneficial effects:

[0045] The method for determining the safety boundary of the battery charging strategy of the embodiment of the present application, first, obtains a dynamically adjusted charging strategy; the charging strategy can be dynamically adjusted based on the detection result of whether the battery has lithium deposition during the charging process; secondly, after charging the battery using the adjusted charging strategy, obtain the voltage information of the battery in the static stage; thirdly, based on the voltage information of the battery in the static stage, detect whether the battery has lithium deposition during the charging process; finally, based on the detection result, determine the safety boundary of the battery charging strategy; wherein the safety boundary of the charging strategy includes at least one of the following: the upper limit current without lithium deposition; the lower limit temperature without lithium deposition; the upper limit voltage without lithium deposition. The method of the embodiment of the present application realizes the accurate measurement of the safety boundary of the battery charging strategy without preparing a special battery device, simplifies the detection process, and reduces the detection cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is one of the flow charts of the method for determining the safety boundary of the battery charging strategy according to an embodiment of the present application;

[0047] Figure 2 This is a second flow chart of a method for determining a battery charging strategy safety boundary according to an embodiment of the present application;

[0048] Figure 3 This is a flowchart of a method for determining a battery charging strategy safety boundary according to an embodiment of the present application;

[0049] Figure 4 This is a fourth flow chart of a method for determining a battery charging strategy safety boundary according to an embodiment of the present application;

[0050] Figure 5 One of the schematic diagrams of the voltage curve of the battery in the static stage according to the embodiment of the present application;

[0051] Figure 6 The second schematic diagram of the voltage curve of the battery in the static stage according to the embodiment of the present application;

[0052] Figure 7 A schematic diagram of the structure of a device for determining a battery charging strategy safety boundary according to an embodiment of the present application. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0054] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here. In addition, the "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally represents that the objects associated with each other are in an "or" relationship.

[0055] In conjunction with the accompanying drawings, the method, device and system for determining the safety boundary of the battery charging strategy provided by the embodiments of the present application are described in detail through specific embodiments and their application scenarios.

[0056] like Figure 1 FIG. 1 is a schematic diagram of a method for determining a battery charging strategy safety boundary according to an embodiment of the present application. The method includes:

[0057] Step 101, obtaining a dynamically adjusted charging strategy; the charging strategy can be dynamically adjusted based on a detection result of whether lithium deposition occurs during the charging process of the battery;

[0058] Here, it should be noted that "lithium deposition" is a loss condition of lithium-ion batteries. Specifically, when a lithium-ion battery is charging, Li+ is deintercalated from the positive electrode and embedded in the negative electrode; however, when some abnormal conditions occur: such as insufficient lithium embedding space at the negative electrode, too much resistance to Li+ embedding in the negative electrode, too fast deintercalation of Li+ from the positive electrode but unable to embed the same amount of Li+ into the negative electrode, etc., the Li+ that cannot be embedded in the negative electrode can only obtain electrons on the surface of the negative electrode, thereby forming a silvery-white metallic lithium single substance, which is commonly known as lithium deposition. Lithium deposition can not only reduce battery performance and significantly shorten cycle life, but also limit the fast charging capacity of the battery, and may cause catastrophic consequences such as combustion and explosion.

[0059] In addition, in this step, when the charging strategy is adjusted, one charging parameter in the charging strategy is adjusted each time, thereby achieving measurement of the safety margin of the adjusted charging parameter.

[0060] Step 102, after charging the battery using the adjusted charging strategy, obtain voltage information of the battery in a static stage;

[0061] In this step, the voltage information of the battery in the static stage may be the voltage change of the battery in the static stage after the charging process is completed.

[0062] Step 103, detecting whether lithium deposition occurs during charging of the battery according to voltage information of the battery in a static stage;

[0063] Here, it should be noted that if metallic lithium is precipitated at the negative electrode of the battery during charging, the subsequent storage process of the entire charger can be divided into four stages: normal charging stage: the negative electrode overpotential is greater than 0, at this time only the reaction of lithium embedding into graphite occurs; lithium precipitation stage: starting from the negative electrode overpotential less than 0V, lithium precipitation reaction occurs, a small part of which generates solid electrolyte interface (Solid Electrolyte Interphase, SEI) film or dead lithium, most of which exists in the form of reversible lithium; reversible lithium dissolution and re-embedding stage: the negative electrode overpotential rises back to above 0V, the reversible lithium dissolves in the electrolyte, and begins to re-embed into the graphite. This stage may occur during constant voltage charging or the initial stage of storage; complete storage stage: all reversible lithium is completely dissolved, and the negative electrode no longer reacts. Among them, the process of the precipitated lithium being re-embedded into the graphite will cause the battery static voltage curve to appear as follows Figure 5 To further amplify and capture this feature, the static voltage curve of the battery is differentiated to obtain the dV / dt-t curve (as shown in the figure). Figure 6 As shown in the figure, when the curve has a minimum value, it proves that metallic lithium is precipitated during this charging. The duration of the voltage platform (i.e., the time t_m when the minimum value of the dV / dt-t curve appears) is linearly related to the amount of reversible lithium. At the same time, reversible lithium and dead lithium satisfy a fixed ratio (determined by the battery cell), which can be used for quantitative detection of reversible lithium and dead lithium. Therefore, the voltage information of the battery in the static stage can be used to detect whether there is lithium precipitation during the charging process.

[0064] Step 104: Determine the safety boundary of the charging strategy of the battery according to the detection result; wherein the safety boundary of the charging strategy includes at least one of the following:

[0065] The upper limit current without lithium deposition;

[0066] The lower limit temperature for no lithium precipitation;

[0067] The upper limit voltage without lithium deposition.

[0068] In this step, the upper limit current without lithium deposition refers to the maximum safe current value at which no lithium deposition signal appears at a certain temperature during the charging process; the lower limit temperature without lithium deposition refers to the lowest temperature value at which no lithium deposition signal appears under a certain charging current during the charging process; the upper limit voltage without lithium deposition refers to the highest voltage value at which no lithium deposition signal appears under a certain temperature and charging current during the charging process.

[0069] The method for determining the safety boundary of the battery charging strategy of the embodiment of the present application, first, obtains a dynamically adjusted charging strategy; the charging strategy can be dynamically adjusted based on the detection result of whether the battery has lithium deposition during the charging process; secondly, after charging the battery using the adjusted charging strategy, obtain the voltage information of the battery in the static stage; thirdly, based on the voltage information of the battery in the static stage, detect whether the battery has lithium deposition during the charging process; finally, based on the detection result, determine the safety boundary of the battery charging strategy; wherein the safety boundary of the charging strategy includes at least one of the following: the upper limit current without lithium deposition; the lower limit temperature without lithium deposition; the upper limit voltage without lithium deposition. The method of the embodiment of the present application realizes the accurate measurement of the safety boundary of the battery charging strategy without preparing a special battery device, simplifies the detection process, and reduces the detection cost.

[0070] As an optional implementation, the charging strategy includes: at least one of a charging cut-off voltage and a charging temperature:

[0071] The charging strategy is dynamically adjusted based on the detection result of whether lithium deposition occurs during the charging process of the battery, including at least one of the following:

[0072] When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the first charging strategy, reducing the charging temperature in the first charging strategy to obtain an adjusted charging strategy;

[0073] When it is detected that no lithium deposition occurs during the process of charging the battery using the first charging strategy, the charging cut-off voltage in the first charging strategy is increased to obtain an adjusted charging strategy.

[0074] That is to say, when determining the upper limit voltage without lithium deposition, the charging cut-off voltage in the charging strategy is adjusted according to whether lithium deposition occurs during the charging process; when determining the lower limit temperature without lithium deposition, the charging temperature in the charging strategy is adjusted according to whether lithium deposition occurs during the charging process, so as to achieve the adjustment of a single parameter and determine the safety boundary of the adjusted parameter.

[0075] As an optional implementation, step 104, determining the safety boundary of the battery charging strategy according to the detection result, includes:

[0076] When the detection result corresponding to the adjusted charging strategy is the presence of lithium deposition, at least one of the charging cut-off voltage and the charging temperature included in the charging strategy used in the previous charging process adjacent to the charging process with lithium deposition is determined as the safety boundary of the charging strategy.

[0077] That is to say, when determining the lower limit temperature without lithium deposition, if lithium deposition is detected during the charging process at the current temperature, the lower limit temperature without lithium deposition of the battery is determined to be the battery temperature of the charging strategy of the previous charging process; when determining the upper limit voltage without lithium deposition, if lithium deposition is detected during the charging process of the current charging cut-off voltage, the upper limit voltage without lithium deposition of the battery is determined to be the charging cut-off voltage in the charging strategy of the previous charging process.

[0078] Next, combine Figure 2 The process of determining the lower limit temperature for no lithium precipitation is explained as follows:

[0079] When the current charging strategy meets the condition of no lithium deposition at any temperature point and charging rate, the lithium deposition safety current can be evaluated. This section simulates the scenario where the actual battery charging rate is greater than the maximum allowable charging current at the temperature due to the temperature sensor acquisition error (5°C) and the temperature difference between the inside and outside of the battery cell. The evaluation is achieved by adjusting the charging temperature under a certain charging strategy during the charging process. The specific process is as follows (reference Figure 2 ):

[0080] The battery temperature is adjusted down by 5°C from the original temperature; that is, the current charging strategy is tested at the original charging temperature minus 5°C (refer to the impact of the temperature acquisition error of the battery management system and the distribution of the lowest and highest temperatures in the battery pack);

[0081] Determine whether there is lithium deposition, that is, whether the lithium deposition signal can be detected under the current charging current after confirming the temperature adjustment according to the lithium deposition detection method;

[0082] If it is determined that lithium deposition occurs, that is, a lithium deposition signal is detected, the original charging temperature is considered to be the lower limit temperature for no lithium deposition (at the same time, the lithium deposition signal is detected when charging at the lower limit temperature for no lithium deposition minus 5°C);

[0083] If it is determined that there is no lithium deposition phenomenon, then reduce the original temperature by 10°C and conduct the test;

[0084] The lower limit temperature at which no lithium is deposited is determined according to the lithium deposition test results at each charging current (the lower limit temperature at which no lithium is deposited may be different at different charging currents).

[0085] That is to say, the process of determining the lower limit temperature without lithium precipitation is, on the basis that there is no lithium precipitation in the charging process at the original temperature, the charging temperature is reduced by 5°C on the basis of the original temperature, and whether there is lithium precipitation in the charging process at the adjusted temperature is detected. If so, the lower limit temperature without lithium precipitation is determined to be the original temperature; if not, the charging temperature is reduced by 10°C on the basis of the original temperature, and whether there is lithium precipitation in the charging process at the adjusted temperature is detected. If so, the lower limit temperature without lithium precipitation is determined to be the original temperature minus 5°C; if not, the temperature is further reduced by 15°C on the basis of the original temperature and detected, and this cycle is repeated until lithium precipitation is detected.

[0086] Next, combine Figure 3 The process of determining the upper limit voltage without lithium deposition is described as follows:

[0087] The current charging strategy satisfies the condition that lithium deposition does not occur at any temperature point and charging rate. The lithium deposition safety voltage can be evaluated. This section simulates the scenario where the battery charging process exceeds the cut-off voltage limit due to the voltage sensor acquisition error. The evaluation is achieved by adjusting a certain temperature during the charging process and the charging cut-off voltage under a specific charging strategy. The specific process is as follows (refer to Figure 3 ):

[0088] The charging cut-off voltage is increased by 50mV based on the original charging cut-off voltage, that is, the charging cut-off voltage of the current charging strategy is increased or decreased by 50mV (the upper limit of each voltage is increased by 50mV for more than one charge) for testing;

[0089] Determine whether there is lithium deposition, that is, whether the lithium deposition signal can be detected after adjusting the upper limit of the charging cut-off voltage according to the lithium deposition detection method;

[0090] If it is determined that lithium deposition occurs, that is, a lithium deposition signal is detected, the original charge cut-off voltage is considered to be the upper limit voltage without lithium deposition;

[0091] If it is determined that there is no lithium deposition phenomenon, the original charging cut-off voltage is increased by 100mV and tested until the lithium deposition signal is detected (at the same time, the lithium deposition signal is detected when charging at the upper limit voltage without lithium deposition plus 50mV), then it is considered that the cut-off voltage under the current charging temperature and charging strategy is the upper limit voltage without lithium deposition;

[0092] According to the lithium deposition test results, the upper limit voltage without lithium deposition under each charging temperature and charging strategy is determined (the upper limit voltage without lithium deposition under different temperatures and charging strategies may be different).

[0093] That is to say, the process of determining the upper limit voltage without lithium deposition is, on the basis that there is no lithium deposition phenomenon in the charging process under the original charging cut-off voltage, the charging cut-off voltage is increased by 100mV on the basis of the original charging cut-off voltage, and it is detected whether there is lithium deposition in the charging process under the adjusted charging cut-off voltage. If so, the upper limit voltage without lithium deposition is determined to be the original charging cut-off voltage; if not, the charging cut-off voltage is increased by 100mV on the basis of the original cut-off voltage, and it is detected whether there is lithium deposition in the charging process under the adjusted charging cut-off voltage. If so, the upper limit voltage without lithium deposition is determined to be the original charging cut-off voltage plus 50mV; if not, the charging cut-off voltage is further increased by 150mV on the basis of the original charging cut-off voltage and detected, and this cycle is repeated until lithium deposition is detected.

[0094] As an optional implementation, the charging strategy includes: charging current;

[0095] The charging strategy is dynamically adjusted based on the detection result of whether lithium deposition occurs during the charging process of the battery, including at least one of the following:

[0096] When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the second charging strategy, and the second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is increased by a first preset adjustment value to obtain an adjusted third charging strategy; the first charging current is the charging current in the charging strategy used in the previous charging process adjacent to the process of charging the battery using the second charging strategy;

[0097] When it is detected that lithium deposition occurs during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fourth charging strategy; the second preset adjustment value is less than the first preset adjustment value;

[0098] When it is detected that lithium deposition occurs during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is less than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fifth charging strategy.

[0099] That is to say, depending on whether lithium deposition occurs during the charging process, the charging current can be increased or decreased to determine the upper limit current without lithium deposition.

[0100] Furthermore, as an optional implementation, the method further includes:

[0101] When the fifth charging current corresponding to the adjusted fifth charging strategy is the preset current, the adjustment of the charging strategy based on the detection result of whether lithium deposition occurs during the charging process of the battery is stopped.

[0102] That is to say, since it is known that there is no lithium plating in the charging process using a charging strategy that includes the original charging current, in order to avoid repeated testing of a charging strategy in which the current is the original charging current or less than the original charging current, this optional implementation method will no longer adjust the charging strategy when the charging current corresponding to the adjusted charging strategy reaches the preset current.

[0103] As an optional implementation, step 104, determining the safety boundary of the charging strategy of the battery according to the detection result, includes at least one of the following:

[0104] When it is detected that no lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the charging current corresponding to the fourth charging strategy is the no-lithium deposition upper limit current;

[0105] When it is detected that lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the difference between the charging current corresponding to the fourth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current;

[0106] When it is detected that lithium deposition occurs during charging of the battery using the fifth charging strategy and the charging current corresponding to the fifth charging strategy is a preset current, determining that the difference between the charging current corresponding to the fifth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current;

[0107] When it is detected that no lithium deposition occurs during the charging of the battery using the fifth charging strategy, the charging current corresponding to the fifth charging strategy is determined to be the no-lithium deposition upper limit current.

[0108] That is to say, in two adjacent charging processes, when lithium deposition occurs in one charging process and not in the other charging process, the upper limit current without lithium deposition is determined to be the charging current corresponding to the charging strategy used in the charging process without lithium deposition.

[0109] Next, combine Figure 4 The process of determining the upper limit current without lithium deposition is explained as follows:

[0110] When the current charging strategy meets the condition that lithium deposition does not occur at any temperature point and charging rate, the lithium deposition safety current can be evaluated. This section simulates the scenario where the current exceeds the current maximum allowed charging current due to errors in the BMS and charging pile current collection or other situations. The evaluation is achieved by adjusting the charging current at a specific temperature in the charging strategy. The specific process is as follows (refer to Figure 4 ):

[0111] The charging current is adjusted to 1.2 times of the original charging current; that is, the charging current at different temperatures in the current charging strategy is adjusted to 1.2 times of the original current (refer to the current fault threshold in the BMS parameter table), and the adjusted current is used to charge the battery at different temperatures;

[0112] Determine whether there is lithium deposition, that is, confirm whether the lithium deposition signal can be detected at the current charging current at each temperature according to the lithium deposition detection method;

[0113] If it is determined that lithium deposition occurs, that is, if a lithium deposition signal is detected, the charging current is adjusted to 1.15 times, and detection is restarted until no lithium deposition signal is detected (at the same time, the lithium deposition signal is detected after the upper limit current of no lithium deposition is increased by 0.05 times the initial current), then the current charging current is considered to be the upper limit current of no lithium deposition at this temperature;

[0114] If it is determined that there is no lithium deposition phenomenon, that is, if no lithium deposition signal is detected, the charging current is adjusted to 1.3 times, and the detection is restarted until a lithium deposition signal is detected (at the same time, the lithium deposition signal is detected after the upper limit current of no lithium deposition is increased by 0.05 times the initial current), then the current charging current is considered to be the upper limit current of no lithium deposition at this temperature.

[0115] The upper limit current without lithium deposition at each temperature point is determined according to the lithium deposition test results (the multiple relationship between the upper limit current without lithium deposition and the original charging current at different temperature points may be different).

[0116] As an optional implementation, step 103, detecting whether lithium deposition occurs during charging of the battery according to voltage information of the battery in a static stage, includes:

[0117] When the voltage information of the battery in the static stage is a voltage curve and the voltage curve has a minimum value, it is determined that lithium deposition occurs in the battery during the charging process.

[0118] Specifically, Figure 5 and Figure 6 As shown in the figure, the re-embedding of the precipitated lithium into graphite will cause the battery static voltage to have a platform. In order to further amplify and capture this feature, the battery static voltage curve ( Figure 5 The curve in ( ) is differentiated to obtain the dV / dt-t curve ( Figure 6When the curve has a minimum value, it proves that metallic lithium is precipitated during the charging.

[0119] The method for determining the safety boundary of the battery charging strategy in the embodiment of the present application is as follows: first, a dynamically adjusted charging strategy is obtained; the charging strategy can be dynamically adjusted based on the detection result of whether the battery has lithium deposition during the charging process; second, after charging the battery using the adjusted charging strategy, the voltage information of the battery in the static stage is obtained; third, based on the voltage information of the battery in the static stage, whether the battery has lithium deposition during the charging process is detected; finally, based on the detection result, the safety boundary of the battery charging strategy is determined; wherein the safety boundary of the charging strategy includes at least one of the following: the upper limit current without lithium deposition; the lower limit temperature without lithium deposition; the upper limit voltage without lithium deposition. In this way, on the one hand, the accurate measurement of the safety boundary of the battery charging strategy is achieved without preparing a special battery device, the detection process is simplified, and the detection cost is reduced; on the other hand, the detection is achieved in combination with the internal sharp and close madness of the battery shelf voltage, and the final lithium deposition state detection of the battery is achieved.

[0120] like Figure 7 As shown, the embodiment of the present application also provides a device for determining a battery charging strategy safety boundary, including:

[0121] A first acquisition module 701 is used to acquire a dynamically adjusted charging strategy; the charging strategy can be dynamically adjusted based on a detection result of whether lithium deposition occurs during the charging process of the battery;

[0122] The second acquisition module 702 is used to acquire voltage information of the battery in a static stage after charging the battery using the adjusted charging strategy;

[0123] The detection module 703 is used to detect whether there is lithium deposition in the battery during the charging process according to the voltage information of the battery in the static stage;

[0124] The determination module 704 is used to determine the safety boundary of the charging strategy of the battery according to the detection result; wherein the safety boundary of the charging strategy includes at least one of the following:

[0125] The upper limit current without lithium deposition;

[0126] The lower limit temperature for no lithium precipitation;

[0127] The upper limit voltage without lithium deposition.

[0128] The device for determining the safety boundary of the battery charging strategy in the embodiment of the present application, first, the first acquisition module 701 acquires the dynamically adjusted charging strategy; the charging strategy can be dynamically adjusted based on the detection result of whether the battery has lithium deposition during the charging process; secondly, the second acquisition module 702 uses the adjusted charging strategy to charge the battery respectively, and then obtains the voltage information of the battery in the static stage; thirdly, the detection module 703 detects whether the battery has lithium deposition during the charging process according to the voltage information of the battery in the static stage; finally, the determination module 704 determines the safety boundary of the battery charging strategy according to the detection result; wherein the safety boundary of the charging strategy includes at least one of the following: the upper limit current without lithium deposition; the lower limit temperature without lithium deposition; the upper limit voltage without lithium deposition. In this way, on the one hand, the accurate measurement of the safety boundary of the battery charging strategy is realized without preparing a special battery device, the detection process is simplified, and the detection cost is reduced; on the other hand, the detection is realized by combining the internal sharp and close madness of the battery shelf voltage, and the final lithium deposition state detection of the battery is realized.

[0129] Optionally, the charging strategy includes: at least one of a charging cut-off voltage and a charging temperature:

[0130] The first acquisition module 701 is used to dynamically adjust the charging strategy based on the detection result of whether the battery has lithium deposition during the charging process, specifically for:

[0131] When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the first charging strategy, reducing the charging temperature in the first charging strategy to obtain an adjusted charging strategy;

[0132] Alternatively, when it is detected that no lithium deposition occurs during the process of charging the battery using the first charging strategy, the charging cut-off voltage in the first charging strategy is increased to obtain an adjusted charging strategy.

[0133] Optionally, the determination module 704 is specifically used to: when the detection result corresponding to the adjusted charging strategy is the presence of lithium deposition, determine that at least one of the charging cut-off voltage and the charging temperature contained in the charging strategy used in the previous charging process adjacent to the charging process with the presence of lithium deposition is the safety boundary of the charging strategy.

[0134] Optionally, the charging strategy includes: charging current;

[0135] The first acquisition module 701 is used to dynamically adjust the charging strategy based on the detection result of whether the battery has lithium deposition during the charging process, specifically for:

[0136] When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the second charging strategy, and the second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is increased by a first preset adjustment value to obtain an adjusted third charging strategy; the first charging current is the charging current in the charging strategy used in the previous charging process adjacent to the process of charging the battery using the second charging strategy;

[0137] Alternatively, when it is detected that lithium deposition occurs during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fourth charging strategy; the second preset adjustment value is less than the first preset adjustment value;

[0138] Alternatively, when lithium deposition is detected during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is less than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fifth charging strategy.

[0139] Furthermore, the device also includes:

[0140] The stopping module is used to stop adjusting the charging strategy based on the detection result of whether lithium deposition occurs during the charging process of the battery when the fifth charging current corresponding to the adjusted fifth charging strategy is a preset current.

[0141] Optionally, the determining module 704 is specifically configured to:

[0142] When it is detected that no lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the charging current corresponding to the fourth charging strategy is the no-lithium deposition upper limit current;

[0143] Alternatively, when it is detected that lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the difference between the charging current corresponding to the fourth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current;

[0144] Alternatively, when it is detected that lithium deposition occurs during charging of the battery using the fifth charging strategy and the charging current corresponding to the fifth charging strategy is a preset current, determining that the difference between the charging current corresponding to the fifth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current;

[0145] Alternatively, when it is detected that no lithium deposition occurs during the charging of the battery using the fifth charging strategy, the charging current corresponding to the fifth charging strategy is determined to be the no-lithium deposition upper limit current.

[0146] Optionally, the detection module 703 is specifically used to: determine that lithium deposition occurs in the battery during charging when the voltage information of the battery in the static stage is a voltage curve and the voltage curve has a minimum value.

[0147] An embodiment of the present application also provides a system for determining a battery charging strategy safety boundary, including: a processor, a memory, and a program stored in the memory and executable on the processor. When the program is executed by the processor, the various processes of the embodiment of the method for determining a battery charging strategy safety boundary as described above are implemented, and the same technical effect can be achieved. In order to avoid repetition, it will not be described here.

[0148] The embodiment of the present application also provides a readable storage medium, on which a program is stored, and when the program is executed by a processor, each process of the embodiment of the method for determining the safety boundary of the battery charging strategy is implemented, and the same technical effect can be achieved. To avoid repetition, it is not repeated here. Among them, the readable storage medium, such as a read-only memory (Read-Only Memory, referred to as ROM), a random access memory (Random Access Memory, referred to as RAM), a disk or an optical disk, etc.

[0149] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0150] The above is a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles described in the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for determining a safety margin of a battery charging strategy, characterized in that: include: Obtain dynamically adjusted charging strategies; The charging strategy can be dynamically adjusted based on the detection result of whether there is lithium deposition in the battery during the charging process; After charging the batteries using the adjusted charging strategies respectively, voltage information of the batteries in a static stage is obtained; Detecting whether lithium deposition occurs during charging of the battery according to voltage information of the battery at rest; Determine the safety margin of the charging strategy of the battery according to the detection result; wherein the safety margin of the charging strategy includes at least one of the following: The upper limit current without lithium deposition; The lower limit temperature for no lithium precipitation; Upper limit voltage without lithium deposition; The charging strategy includes at least one of a charging cut-off voltage, a charging temperature and a charging current: The charging strategy is dynamically adjusted based on the detection result of whether lithium deposition occurs during the charging process of the battery, including at least one of the following: When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the first charging strategy, reducing the charging temperature in the first charging strategy to obtain an adjusted charging strategy; When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the first charging strategy, increasing the charging cut-off voltage in the first charging strategy to obtain an adjusted charging strategy; When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the second charging strategy, and the second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is increased by a first preset adjustment value to obtain an adjusted third charging strategy; the first charging current is the charging current in the charging strategy used in the previous charging process adjacent to the process of charging the battery using the second charging strategy; When it is detected that lithium deposition occurs during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fourth charging strategy; the second preset adjustment value is less than the first preset adjustment value; When it is detected that lithium deposition occurs during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is less than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fifth charging strategy; Wherein, determining the safety boundary of the charging strategy of the battery according to the detection result includes at least one of the following: When the detection result corresponding to the adjusted charging strategy is that lithium deposition occurs, determining at least one of a charging cutoff voltage and a charging temperature included in a charging strategy used in a previous charging process adjacent to the charging process in which lithium deposition occurs as a safety boundary of the charging strategy; When it is detected that no lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the charging current corresponding to the fourth charging strategy is the no-lithium deposition upper limit current; When it is detected that lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the difference between the charging current corresponding to the fourth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current; When it is detected that lithium deposition occurs during charging of the battery using the fifth charging strategy and the charging current corresponding to the fifth charging strategy is a preset current, determining that the difference between the charging current corresponding to the fifth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current; When it is detected that no lithium deposition occurs during the charging of the battery using the fifth charging strategy, the charging current corresponding to the fifth charging strategy is determined to be the no-lithium deposition upper limit current.

2. The method according to claim 1, characterized in that The method further comprises: When the fifth charging current corresponding to the adjusted fifth charging strategy is the preset current, the adjustment of the charging strategy based on the detection result of whether lithium deposition occurs during the charging process of the battery is stopped.

3. The method according to claim 1, characterized in that Detecting whether the battery has lithium deposition during charging according to the voltage information of the battery in the static stage includes: When the voltage information of the battery in the static stage is a voltage curve and the voltage curve has a minimum value, it is determined that lithium deposition occurs in the battery during the charging process.

4. A device for determining a safety boundary of a battery charging strategy, characterized in that: include: A first acquisition module, used to acquire a dynamically adjusted charging strategy; The charging strategy can be dynamically adjusted based on the detection result of whether there is lithium deposition in the battery during the charging process; A second acquisition module is used to acquire voltage information of the battery in a static stage after charging the battery using the adjusted charging strategy; A detection module, used to detect whether there is lithium deposition in the battery during charging according to the voltage information of the battery in the static stage; A determination module is used to determine the safety boundary of the charging strategy of the battery according to the detection result; wherein the safety boundary of the charging strategy includes at least one of the following: The upper limit current without lithium deposition; The lower limit temperature for no lithium precipitation; Upper limit voltage without lithium deposition; Wherein, the charging strategy includes: at least one of a charging cut-off voltage, a charging temperature and a charging current; When the first acquisition module is used to dynamically adjust the charging strategy based on the detection result of whether the battery has lithium deposition during the charging process, it is specifically used to: When it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the first charging strategy, reducing the charging temperature in the first charging strategy to obtain an adjusted charging strategy; Alternatively, when it is detected that no lithium deposition occurs during the charging of the battery using the first charging strategy, the charging cut-off voltage in the first charging strategy is increased to obtain an adjusted charging strategy; Alternatively, when it is detected that there is no lithium deposition phenomenon in the process of charging the battery using the second charging strategy, and the second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is increased by a first preset adjustment value to obtain an adjusted third charging strategy; the first charging current is the charging current in the charging strategy used in the previous charging process adjacent to the process of charging the battery using the second charging strategy; Alternatively, when it is detected that lithium deposition occurs during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is greater than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fourth charging strategy; the second preset adjustment value is less than the first preset adjustment value; Alternatively, when it is detected that lithium deposition occurs during charging of the battery using the second charging strategy, and a second charging current corresponding to the second charging strategy is less than the first charging current, the second charging current is reduced by a second preset adjustment value to obtain an adjusted fifth charging strategy; Wherein, the determination module is specifically used for: When the detection result corresponding to the adjusted charging strategy is that lithium deposition occurs, determining at least one of a charging cutoff voltage and a charging temperature included in a charging strategy used in a previous charging process adjacent to the charging process in which lithium deposition occurs as a safety boundary of the charging strategy; Alternatively, when it is detected that no lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the charging current corresponding to the fourth charging strategy is the no-lithium deposition upper limit current; Alternatively, when it is detected that lithium deposition occurs during charging of the battery using the fourth charging strategy, determining that the difference between the charging current corresponding to the fourth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current; Alternatively, when it is detected that lithium deposition occurs during charging of the battery using the fifth charging strategy and the charging current corresponding to the fifth charging strategy is a preset current, determining that the difference between the charging current corresponding to the fifth charging strategy and the second preset adjustment value is the no-lithium deposition upper limit current; Alternatively, when it is detected that no lithium deposition occurs during the charging of the battery using the fifth charging strategy, the charging current corresponding to the fifth charging strategy is determined to be the no-lithium deposition upper limit current.

5. A system for determining the safety margin of a battery charging strategy, characterized in that: include: A processor, a memory, and a program stored in the memory and executable on the processor, wherein when the program is executed by the processor, the steps of the method for determining the safety boundary of a battery charging strategy as described in any one of claims 1 to 3 are implemented.

6. A readable storage medium, characterized in that: The readable storage medium stores a program, and when the program is executed by a processor, the steps of the method for determining the safety boundary of a battery charging strategy according to any one of claims 1 to 3 are implemented.

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