Battery thermal runaway hidden danger recognizing method and device, terminal, and storage medium

Abstract

The present application discloses a battery thermal runaway hidden danger recognizing method and device, a terminal, and a storage medium. A rigid mechanism is mounted on the side of a battery in an expansion direction, and a pressure sensor is mounted on the side of the rigid mechanism not in contact with the battery. The method comprises: acquiring a pressure value of the pressure sensor, establishing an initial pressure reference, and recording the current pressure value of the pressure sensor as an initial pressure value FP0; on the basis of the range of the pressure sensor and the initial pressure value FP0, determining whether the pressure sensor fails, and if yes, giving a pressure sensor failure alarm; and if not, acquiring a pressure value of the pressure sensor in real time on the basis of a measurement frequency f, and on the basis of the pressure value acquired in real time, recognizing whether a battery explosion-proof valve is turned on. The method, the device using the method, the terminal, and the storage medium improve the recognizing precision of battery thermal runaway hidden dangers.

Description

A battery thermal runaway hazard identification method, device, terminal and storage medium Technical Field

[0001] The present application relates to the field of battery safety control technology, and in particular to a method, device, terminal, and storage medium for identifying battery thermal runaway hazards. Background Art

[0002] Currently, lithium batteries are widely used in electric vehicles or energy storage systems. Whether it is electric vehicles or energy storage applications, the safety of lithium batteries has always been a hot topic of discussion, and the prevention and identification of thermal runaway of batteries is also an important consideration factor in battery safety. Although the design of the battery cell itself has taken into account the investigation of thermal runaway hazards, such as the insulation design, NP ratio design, explosion-proof valve design, etc. of the battery cell, after these design elements are parameterized, qualified fresh battery cells themselves are safe; in addition, if these variables can be detected at any time during the system design and application process, then throughout the life of the battery cell, its safety is predictable and controllable to a certain extent, and in theory, thermal runaway will not occur and cause an explosion.

[0003] However, the reality is that the safety design of the battery cell itself is almost entirely encapsulated within the cell, making it difficult to detect effectively. Currently, the most feasible detection target is the explosion-proof valve located on the surface of the battery cell. The explosion-proof valve, also known as the safety valve, is the last barrier after the cell structure fails and before explosion. By identifying the opening of the explosion-proof valve, it is determined whether the battery has the risk of thermal runaway. Currently, there are two mainstream designs for identifying whether the battery explosion-proof valve is open:

[0004] One method is to determine the opening pressure of the battery explosion-proof valve to provide a basis for the design of the battery pack or battery group and prevent battery explosion. The principle is to use the pressure-bearing performance data of the battery pack's thermal insulation components, such as the component's stress area, thickness parameters, temperature parameters, etc., to associate this data with the compression rate of the thermal insulation components to determine the opening pressure of the battery pack explosion-proof valve. In actual implementation, this method requires the collection of the pressure value inside the battery cell. This method has the following disadvantages:

[0005] (1) It requires strong professionalism. Improper operation will introduce new safety hazards. The reason is that it is necessary to collect the pressure value inside the battery cell, which is equivalent to implanting an air pressure sensor inside the battery cell. Existing standard equipment cannot achieve this. Manual operation is required. Once the manual operation is improper, even if the hand shakes, it may cause a short circuit in the battery cell, resulting in thermal runaway. Therefore, the professionalism of the operation is extremely high.

[0006] (2) It will reduce the energy density of the battery; the reason is that the air pressure sensor needs to occupy the internal space of the battery cell, which makes this part of the space unable to participate in the electrochemical reaction of the battery during the charging and discharging process, and therefore cannot express the charging and discharging energy, thus reducing the energy density of the battery;

[0007] (3) It may also reduce the service life of the battery; the reason is that the transmission path of lithium ions around the implanted sensor is affected, which may cause lithium deposition, thereby causing the battery attenuation mode to change, thereby reducing the battery service life.

[0008] Another method is to detect the air pressure of the battery pack or battery compartment and determine whether the battery pack or battery compartment has triggered the battery explosion-proof valve to open based on the change in air pressure. In actual implementation, the core point of this method is to design a battery vacuum compartment or confined space. This method has the following disadvantages:

[0009] (1) The manufacturing cost is high, and more than one mechanism is required to form a vacuum environment;

[0010] (2) The manufacturing process is very different from the existing battery grouping technology or battery pack technology. Although the welding technology that protects the vacuum environment is currently used in the battery cell process, it has almost no relevant application in the battery grouping process, and the technology is not yet mature;

[0011] (3) The variables that need to be controlled during the transportation and use of the battery vacuum chamber are also quite different from the typical design of battery PACK technology. If these variables are not well controlled, the vacuum chamber may be damaged.

[0012] Therefore, in the existing technology, the methods of monitoring whether the battery explosion-proof valve is open and then identifying the hidden dangers of battery thermal runaway, whether it is the method of collecting the internal pressure value of the battery cell or the method of designing a vacuum chamber or a confined space, all have certain difficulties, which affect the design parameters of the battery and even cause instability in the valve opening pressure of the explosion-proof valve, making it difficult to determine the time node when the explosion-proof valve opens; moreover, since the air pressure when the explosion-proof valve is opened is generally between 0.3 and 0.8 MPa, this range itself is relatively wide. If some external interference forces are added, the valve opening pressure value of the explosion-proof valve will become more discrete, making it more difficult to determine whether the explosion-proof valve is open, and it will be impossible to accurately identify the hidden dangers of battery thermal runaway and issue a timely warning.

[0013] Summary of the Invention

[0014] In order to improve the accuracy of identifying battery thermal runaway hazards, the present application provides a battery thermal runaway hazard identification method, device, terminal and storage medium.

[0015] In a first aspect, the present application provides a method for identifying potential battery thermal runaway hazards, which employs the following technical solution: a rigid structure is installed on one side of the battery in the direction of expansion, and a pressure sensor is installed on the side of the rigid structure that does not contact the battery; the method comprises:

[0016] Obtain the pressure value of the pressure sensor, establish an initial pressure reference, and record the current pressure value of the pressure sensor as the initial pressure value F P0 ;

[0017] Based on the range of the pressure sensor and the initial pressure value F P0 , determining whether the pressure sensor fails;

[0018] If so, a warning of pressure sensor failure is issued;

[0019] If not, based on the detection frequency f, the pressure value of the pressure sensor is acquired in real time, and based on the pressure value acquired in real time, it is identified whether the battery has a thermal runaway risk.

[0020] By adopting the above technical solution, a pressure sensor and a rigid structure are selected and installed in the direction of battery expansion, and the pressure value of the pressure sensor is obtained in real time. Through a series of calculations and judgments, it can be sensed and warned in time when the explosion-proof valve is opened, thereby achieving high-precision identification of the hidden dangers of battery thermal runaway. Compared with the existing method of detecting pressure inside the battery, the technical solution of the present application does not require the use of an air pressure sensor to detect the internal air pressure of the battery cell, and avoids the position of the explosion-proof valve. It is directly outside the battery, without destroying the internal structure and parameters of the battery, and without designing a battery vacuum chamber or enclosed space. It not only effectively suppresses the expansion of the battery cell, but is also beneficial to the positive and negative electrodes of the battery cell and the diaphragm to maintain the lithium ion channel, and can delay the battery capacity diving. The technical solution of the present application can be applied to single-cell, multi-cell or battery module cases, and is more convenient to use.

[0021] In a specific implementation scheme, before acquiring the pressure value of the pressure sensor in real time based on the detection frequency f, the method further includes:

[0022] Obtaining operating data of the battery, and determining whether the battery currently has a potential risk event based on the operating data of the battery;

[0023] If yes, the preset initial detection frequency f1 is adjusted to obtain the detection frequency f;

[0024] The potential risk events include one or more of the following: a battery short circuit time exceeding a preset short circuit time threshold; a battery overcharge time exceeding a preset overcharge time threshold; and a battery temperature rise rate exceeding a preset temperature rise rate threshold.

[0025] By adopting the above technical solution, staff can set an initial detection frequency f1 for the battery. In actual application, when the battery is judged to have a potential risk event based on the battery operation data, it means that the probability of the explosion-proof valve opening during this period is higher, and the probability of the battery thermal runaway is also higher. Therefore, the initial detection frequency f1 can be increased accordingly to improve the accuracy of identifying the hidden dangers of battery thermal runaway.

[0026] In a specific implementation scheme, based on the detection frequency f, the pressure value of the pressure sensor is acquired in real time, and based on the real-time acquired pressure value, whether the battery has a thermal runaway risk is identified, specifically including:

[0027] Based on the detection frequency f, a number of detection time nodes are generated, and at each detection time node, the pressure value of the pressure sensor, the cycle number a of the battery, and the ambient temperature T of the battery are obtained in real time;

[0028] Based on the pressure value of the pressure sensor, a pressure value sequence Q1 is obtained, where Q1={F P1 , F P2 , F P3 ...F Pn}; where n is a natural number, F Pn Indicates the pressure value corresponding to the pressure sensor at the nth detection time node;

[0029] Based on the cycle number a, the ambient temperature T and the pre-built expansion force estimation model, the expansion force value of the battery is estimated to obtain the expansion force value sequence Q2, Q2 = {F e1 , F e2 , F e3 ...F en}; where n is a natural number, F en Indicates the expansion force value of the battery at the nth detection time node;

[0030] Based on the pressure value sequence Q1 and the expansion force value sequence Q2, it is determined whether each pressure value in the pressure value sequence Q1 and the corresponding expansion force value in the expansion force value sequence Q2 satisfy the following conditions: Pn ≤F P0 +F en If so, it is determined that the battery has a thermal runaway risk and an early warning is issued.

[0031] By adopting the above technical solution, when the battery cycle number a and the ambient temperature T change, the battery expansion force will also change continuously. Therefore, in the process of identifying the hidden danger of battery thermal runaway, on the one hand, the battery expansion force value is estimated based on the battery cycle number a and the ambient temperature T through the expansion force estimation model; on the other hand, based on the pressure value obtained by the real-time pressure sensor, through multiple comparisons and judgments, if the actual collected pressure value and the estimated expansion force value meet F for multiple consecutive times, Pn ≤F P0 +F en , indicating that the actual pressure inside the battery is lower than the theoretical estimate over a period of time. At this point, it can be determined that the explosion-proof valve has opened and is releasing pressure from the battery. This can also provide an accurate warning of the potential for thermal runaway, facilitating timely manual intervention and effectively avoiding misjudgments.

[0032] In a specific embodiment, the expansion force estimation model includes: F e =k1*ln(a)+△F e +m;

[0033] Among them, F e is the expansion force value, the unit is kN; k1 is the cyclic attenuation characteristic, the unit is kN; a is the number of cycles; △F e Characterizes the effect of ambient temperature T on the expansion force. When ambient temperature T<T s When △F e =0, when the ambient temperature T≥T s When △F e =k2*(TT s ) 2 , k2 is the temperature characteristic quantity, the unit is kN / ℃ 2 ;T s is the standard ambient temperature; m is the correction value, the unit is kN.

[0034] In a specific possible implementation scheme, based on the detection frequency f, the pressure value of the pressure sensor is obtained in real time, and based on the real-time obtained pressure value, it is identified whether the battery has a thermal runaway risk, which specifically also includes:

[0035] Sliding window sampling is performed on the pressure value sequence Q1 to obtain a pressure value subsequence Q3 {F Pa , F Pa+1 ...F Pb}; where a and b are both natural numbers, and a<b≤n;

[0036] Determine whether the data in the pressure value subsequence Q3 are all greater than F Pmax ;

[0037] If so, it is determined that the pressure sensor is failed and a reminder is issued; wherein, F Pmax is the measuring range of the pressure sensor.

[0038] By adopting the above technical solution, during the process of identifying the hidden dangers of battery thermal runaway, it is possible to detect in real time whether the pressure sensor has failed, thereby avoiding misjudgment caused by the failure of the pressure sensor.

[0039] In a specific embodiment, before obtaining the pressure value of the pressure sensor and establishing the initial pressure reference, the method further includes:

[0040] Controlling the cyclic charge and discharge of the battery, and obtaining the pressure change conditions at various positions on the expansion side of the battery during the cyclic charge and discharge process, to obtain a pressure change cloud diagram of the battery;

[0041] Based on the pressure change cloud map, the installation position of the pressure sensor on the rigid structure is determined.

[0042] In a specific embodiment, the pressure value of the pressure sensor is obtained, an initial pressure reference is established, and the current pressure value of the pressure sensor is recorded as the initial pressure value F P0 , specifically including:

[0043] Obtaining the voltage value output by the pressure sensor, recorded as the initial voltage value V0;

[0044] Based on the initial voltage value V0, and the range, power supply voltage and sensitivity of the pressure sensor, the initial pressure value F is obtained by calculation. P0 ;

[0045] The relationship between the pressure value of the pressure sensor and the voltage value output by the pressure sensor is:

[0046] Pressure value / range=(output voltage value / power supply voltage)*sensitivity.

[0047] By adopting the above technical solution, the initial pressure value F is calculated based on the initial voltage value V0 initially output by the pressure sensor, combined with the range, power supply voltage and sensitivity data of the pressure sensor. P0 By establishing an initial pressure reference value, it is convenient to judge whether the battery has the risk of thermal runaway in the future.

[0048] In a second aspect, the present application provides a battery thermal runaway hazard identification device, which adopts the following technical solution: the device applies the battery thermal runaway hazard identification method according to the first aspect or any possible implementation scheme of the first aspect,

[0049] The device includes an MCU, a rigid structure, and a pressure sensor, wherein the MCU is communicatively connected to the pressure sensor; the rigid structure is installed on the side facing the battery expansion direction, and the pressure sensor is installed on the side of the rigid structure that does not contact the battery;

[0050] The MCU is used to obtain the pressure value of the pressure sensor, establish an initial pressure reference, and record the current pressure value of the pressure sensor as the initial pressure value F P0 ;

[0051] The MCU is further configured to: P0 , determine whether the pressure sensor has failed; if so, the MCU issues a pressure sensor failure reminder; if not, the MCU obtains the pressure value of the pressure sensor in real time based on the detection frequency f, and identifies whether the battery has a thermal runaway risk based on the real-time pressure value.

[0052] In a third aspect, the present application provides a terminal, adopting the following technical solution: the terminal includes a processor, a memory and a communication bus; the communication bus is used to realize the connection and communication between the processor and the memory, and the processor is used to execute one or more programs stored in the memory to realize the battery thermal runaway hazard identification method as described in the first aspect or any possible implementation scheme of the first aspect.

[0053] In a fourth aspect, the present application provides a computer-readable storage medium, which adopts the following technical solution: the computer-readable storage medium stores instructions, and when the instructions are executed, the battery thermal runaway hazard identification method in the above-mentioned first aspect or any possible implementation scheme of the first aspect is executed.

[0054] In summary, the technical solution of this application includes at least the following beneficial technical effects:

[0055] 1. Select a pressure sensor and a rigid structure, install it in the direction of battery expansion, and obtain the pressure value of the pressure sensor in real time. Through a series of calculations and judgments, it can timely sense and issue an early warning when the battery has a thermal runaway risk, thereby improving the accuracy of identifying battery thermal runaway risks;

[0056] 2. Compared with the existing method of detecting pressure inside the battery, the technical solution of the present application does not require the use of an air pressure sensor to detect the air pressure inside the battery cell, and avoids the location of the explosion-proof valve. It is directly outside the battery, without destroying the internal structure and parameters of the battery, and there is no need to design a battery vacuum chamber or a closed space. It not only effectively suppresses the expansion of the battery cell, but also is beneficial to the positive and negative electrodes of the battery cell and the diaphragm to maintain the lithium ion channel, which can delay the battery capacity from plummeting. Moreover, the technical solution of the present application can be applied to single-cell, multi-cell or battery module situations, making it more convenient to use.

[0057] 3. In the process of identifying the hidden dangers of battery thermal runaway, on the one hand, the battery expansion force value is estimated based on the battery cycle number a and the ambient temperature T through the expansion force estimation model; on the other hand, based on the pressure value obtained by the real-time pressure sensor, through multiple comparisons and judgments, if the actual collected pressure value and the estimated expansion force value meet F for multiple consecutive times, Pn ≤F P0 +F en , indicating that the actual pressure inside the battery is lower than the theoretical estimate over a period of time. This indicates that the explosion-proof valve has opened and is releasing pressure from the battery. This provides an accurate warning of thermal runaway potential, facilitating timely manual intervention and effectively avoiding misjudgments. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] FIG1 is an exploded view of a pressure sensor, a rigid structure, and a battery in an embodiment of the present application;

[0059] FIG2 is a schematic diagram of a first flow chart of a method for identifying a potential risk of battery thermal runaway in an embodiment of the present application;

[0060] FIG3 is a schematic diagram of a second flow chart of a method for identifying a potential battery thermal runaway hazard in an embodiment of the present application;

[0061] FIG4 is a schematic diagram showing the relationship between the expansion force value and the number of cycles in an embodiment of the present application;

[0062] FIG5 is a cloud diagram of pressure changes on the expansion side of a battery in an embodiment of the present application;

[0063] FIG6 is a schematic diagram of signal connections of a pressure sensor in an embodiment of the present application. DETAILED DESCRIPTION

[0064] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0065] According to the electrochemical characteristics of lithium batteries, changes in battery expansion force are the result of the combined effects of the deintercalation of lithium from the negative electrode graphite and the macroscopic changes in the positive electrode olivine iron lithium electrode. This expansion rate is strongly correlated with the battery's state of health (SOH). In practice, as the battery's SOH decreases, an irreversible side reaction occurs, generating gas inside the battery, which manifests as battery swelling. When the pressure generated by this expansion force acts on the explosion-proof valve and exceeds its tolerance limit, it will break open. Once the explosion-proof valve opens, the battery will release pressure, but this does not necessarily lead to an immediate fire or explosion. When flammable and explosive gases released from the electrolyte come into contact with oxygen in the air, sparks, such as static electricity or micro-shorting of the electrode sheets, can cause a fire. Therefore, there is a certain amount of time between the opening of the explosion-proof valve and the occurrence of a battery fire. If the battery explosion-proof valve opening point can be accurately identified, the point at which the battery is at risk of thermal runaway can also be precisely identified. Workers can use this time period to take appropriate measures to effectively prevent thermal runaway.

[0066] An embodiment of the present application provides a method for identifying hidden dangers of battery thermal runaway. Taking a battery module composed of square batteries as an example, as shown in Figure 1, the arrangement of the battery, the rigid structure and the pressure sensor is shown in the figure. The rigid structure is installed on the side of the battery expansion direction, and the pressure sensor is installed on the side of the rigid structure that does not contact the battery. The pressure sensor and the rigid structure are fixed to the battery by a fixing plate. Preferably, there is no gap between the pressure sensor and the rigid structure, that is, the gap is 0.

[0067] In the present application, a rigid structure is provided between the pressure sensor and the battery, and the rigid structure is used to transmit the force generated by the battery expansion to the pressure sensor. The provision of the rigid structure has the following advantages: first, it increases the contact area, thereby preventing the pressure sensor from being directly mounted on the battery with a contact area that is too small, which can easily damage the battery housing; second, it facilitates the pressure sensor to better collect the expansion force of the battery, and can better transmit the force generated by the battery expansion to the pressure sensor. When the battery expands at any position on the side in contact with the rigid structure, the rigid structure can bulge, specifically, the center position of the rigid structure bulges; in particular, the rigid structure can be, for example, an aluminum plate with a higher hardness, of course, other materials can also be used, and this application does not impose any restrictions on this. As long as it can contact the battery, the expansion force of any position on that side of the battery can be better transmitted to the pressure sensor.

[0068] As shown in FIG. 2 and FIG. 3 , the method includes steps S1 to S3 .

[0069] S1, obtain the pressure value of the pressure sensor, establish an initial pressure reference, and record the current pressure value of the pressure sensor as the initial pressure value F P0 .

[0070] In a possible implementation, in step S1, the pressure value of the pressure sensor is obtained, an initial pressure reference is established, and the current pressure value of the pressure sensor is recorded as the initial pressure value F P0 , specifically including:

[0071] A1, obtaining the voltage value output by the pressure sensor, recorded as the initial voltage value V0;

[0072] A2, based on the initial voltage value V0, and the range, power supply voltage and sensitivity of the pressure sensor, calculate the initial pressure value F P0 ;

[0073] The relationship between the pressure value of the pressure sensor and the voltage value output by the pressure sensor is:

[0074] Pressure value / range=(output voltage value / power supply voltage)*sensitivity.

[0075] In step A1, after obtaining the voltage value output by the pressure sensor, the voltage value output by the pressure sensor may be subjected to signal conditioning to obtain a more accurate voltage value. The voltage value signal output by the pressure sensor may not be accurately acquired due to a small signal amplitude, or may exceed the acceptable range due to a large signal amplitude, causing damage to the device used to receive the voltage value output by the pressure sensor. Therefore, adding a signal conditioning process can filter out interference noise and improve the accuracy of pressure value acquisition from the pressure sensor.

[0076] Through steps A1-A2, firstly, based on the initial voltage value V0 initially output by the pressure sensor, combined with the range, power supply voltage and sensitivity data of the pressure sensor, the initial pressure value F is calculated. P0 By establishing an initial pressure reference value, it is convenient to judge whether the battery explosion-proof valve is open.

[0077] S2, based on the range of the pressure sensor and the initial pressure value F P0 , determining whether the pressure sensor is failed; if so, issuing a reminder of the failure of the pressure sensor;

[0078] In step S2, it is determined whether the pressure sensor is invalid. Specifically, the following determination method is used: Determine the initial pressure value F P0 Whether 0<F P0 <F Pmax If yes, the pressure sensor is not invalid; if no, the pressure sensor is invalid; where F Pmax is the measuring range of the pressure sensor.

[0079] S3: If not, then based on the detection frequency f, the pressure value of the pressure sensor is obtained in real time, and based on the pressure value obtained in real time, it is identified whether the battery has a thermal runaway risk.

[0080] It should be noted that in step S3, the process of obtaining the pressure value of the pressure sensor in real time refers to steps A1-A2 above. First, the voltage value output by the pressure sensor is obtained, which is recorded as voltage value V. Based on voltage value V, as well as the range, power supply voltage, and sensitivity of the pressure sensor, the corresponding pressure value is calculated using the formula: pressure value / range = (output voltage value / power supply voltage) * sensitivity. This will not be repeated here.

[0081] In a possible implementation, before step S3, obtaining the pressure value of the pressure sensor based on the detection frequency f, further includes the following steps:

[0082] B1, obtaining operating data of the battery, and determining whether the battery currently has a potential risk event based on the operating data of the battery;

[0083] B2, if yes, then adjust the preset initial detection frequency f1 to obtain the detection frequency f;

[0084] If not, the preset initial detection frequency f1 is used as the detection frequency f;

[0085] The potential risk events include one or more of the following: a battery short circuit time exceeding a preset short circuit time threshold; a battery overcharge time exceeding a preset overcharge time threshold; and a battery temperature rise rate exceeding a preset temperature rise rate threshold.

[0086] Staff can set an initial detection frequency f1 for the battery. In actual application, when they determine that the battery has a potential risk event based on the battery's operating data, it means that the probability of the explosion-proof valve opening during this period is higher, and the probability of the battery experiencing thermal runaway is also higher. Therefore, the initial detection frequency f1 can be increased accordingly to obtain the detection frequency f, thereby improving the accuracy of identifying battery thermal runaway hazards.

[0087] Furthermore, those skilled in the art can adjust the detection frequency f based on the number of batteries. Specifically, the battery thermal runaway hazard identification method of the present application embodiment can be applied not only to a single battery group, but also to multiple battery groups simultaneously. The detection frequency f can be increased as the number of battery groups increases.

[0088] In a possible implementation manner, before step S1, the following steps are further included:

[0089] System initialization: The system initialization includes system clock initialization, timer initialization, communication interface initialization and analog sampling ADC initialization.

[0090] In one possible implementation, step S3, based on the detection frequency f, obtaining a pressure value of the pressure sensor in real time, and identifying whether the battery has a thermal runaway risk based on the real-time obtained pressure value, specifically includes the following steps:

[0091] C1, based on the detection frequency f, generates several detection time nodes, and obtains the pressure value of the pressure sensor, the cycle number a of the battery, and the ambient temperature T of the battery in real time at each detection time node;

[0092] C2, based on the pressure value of the pressure sensor, obtains a pressure value sequence Q1, Q1 = {F P1 , F P2 , F P3 ...F Pn}; where n is a natural number, F Pn Indicates the pressure value corresponding to the pressure sensor at the nth detection time node;

[0093] C3, based on the cycle number a, the ambient temperature T and the pre-built expansion force estimation model, estimate the expansion force value of the battery to obtain the expansion force value sequence Q2, Q2 = {F e1 , F e2 , F e3 ... F en}; where n is a natural number, F en Indicates the expansion force value of the battery at the nth detection time node;

[0094] C4, based on the pressure value sequence Q1 and the expansion force value sequence Q2, determining whether each pressure value in the pressure value sequence Q1 and the corresponding expansion force value in the expansion force value sequence Q2 satisfy: F Pn ≤F P0 +F en If so, it is determined that the battery explosion-proof valve is open, that is, it is determined that the battery has a thermal runaway risk, and an early warning is issued to request manual intervention to avoid secondary accidents, such as fire;

[0095] If not, it is determined that the current battery does not have a thermal runaway risk, and the above steps C1-C4 are repeated to continuously monitor the battery.

[0096] It should be noted that, among the several detection time nodes generated above, the time difference between any two adjacent detection time nodes is Δt=1 / f.

[0097] Among them, when the battery undergoes a complete charge and discharge, it indicates that the battery has completed a cycle, that is, the cycle number a of the battery increases once. Preferably, n can be 10, that is, when 10 detection time nodes are generated based on the detection frequency f, and at each detection time node, the pressure value obtained in real time and the estimated expansion force value are satisfied for 10 consecutive times. Pn ≤F P0 +F en , that is, the pressure value collected each time is less than or equal to the initial pressure value F P0 The sum of the measured value and the estimated expansion force value indicates that the battery explosion-proof valve is open and the battery has a thermal runaway risk.

[0098] In a possible implementation, step S3, based on the detection frequency f, obtaining a pressure value of the pressure sensor in real time, and identifying whether the battery has a thermal runaway risk based on the real-time obtained pressure value, specifically further includes:

[0099] C5, perform sliding window sampling on the pressure value sequence Q1 to obtain a pressure value subsequence Q3{F Pa , F Pa+1 ...F Pb}; where a and b are both natural numbers, and a<b≤n;

[0100] Determine whether the data in the pressure value subsequence Q3 are all greater than F Pmax ;

[0101] If so, it is determined that the pressure sensor is failed and a reminder is issued; wherein, F Pmax is the measuring range of the pressure sensor.

[0102] Through the above step C5, during the process of identifying the potential risk of battery thermal runaway, it is detected in real time whether the pressure sensor is failed, thereby avoiding misjudgment caused by the failure of the pressure sensor.

[0103] Through the above steps C1-C4, when the battery cycle number a and the ambient temperature T change, the battery's own expansion force will also change continuously. Therefore, in the process of identifying the hidden danger of battery thermal runaway, on the one hand, the battery expansion force value is estimated based on the battery cycle number a and the ambient temperature T through the expansion force estimation model; on the other hand, based on the pressure value obtained by the real-time pressure sensor, through multiple comparisons and judgments, if the actual collected pressure value and the estimated expansion force value meet F for multiple consecutive times, Pn ≤F P0 +F en , indicating that the actual pressure inside the battery is lower than the theoretical estimate over a period of time. This indicates that the explosion-proof valve has opened and is releasing pressure from the battery. This provides an accurate warning of thermal runaway potential, facilitating timely manual intervention and effectively avoiding misjudgments.

[0104] In a possible implementation, the expansion force estimation model includes: F e =k1*ln(a)+△F e +m;

[0105] Among them, F e is the expansion force value, the unit is kN; k1 is the cyclic attenuation characteristic, the unit is kN; a is the number of cycles; △F e Characterizes the effect of ambient temperature T on the expansion force. When ambient temperature T<T s When △F e =0, when the ambient temperature T≥T s When △F e =k2*(TT s ) 2 , k2 is the temperature characteristic quantity, the unit is kN / ℃ 2 ;T s is the standard ambient temperature; m is the correction value, the unit is kN; the standard ambient temperature T s The unit of the ambient temperature T is ℃.

[0106] It should be noted that those skilled in the art can determine the standard ambient temperature T based on factors such as the type of battery and the change of battery expansion force at different ambient temperatures. s The value of , which is not specifically limited in this application, can be set as the ambient temperature T<T s When the ambient temperature changes, the battery expansion force will not increase. s When the ambient temperature changes, the battery expansion force will increase as the judgment standard, specifically determine the standard ambient temperature T s For example, the standard ambient temperature T s It can be 10°C.

[0107] In a possible implementation, before step S1 acquires the pressure value of the pressure sensor and establishes the initial pressure reference, the following steps are further included:

[0108] D1, collected at standard ambient temperature T s The expansion force value F during the battery cycle charge and discharge process is e , get the expansion force value F e and the first corresponding data between the number of cycles a; and based on the first corresponding data, the expansion force value F is fitted e The first functional relationship between and the number of cycles a;

[0109] Specifically, the first functional relationship is: F e =k1*ln(a)+m; where the expansion force value Fe The unit is kN; k1 is the cyclic attenuation characteristic value, the unit is kN; a is the number of cycles; m is the correction value, the unit is kN.

[0110] Through step D1, the expansion force value F is fitted e After the first functional relationship between the cyclic number a and the cyclic attenuation characteristic value k1 and the correction value m is obtained, the specific values ​​of the cyclic attenuation characteristic value k1 and the correction value m can be obtained.

[0111] D2, respectively collect the expansion force value F of the battery during the cyclic charge and discharge process at different ambient temperatures T e , obtain a second corresponding data set; the second corresponding data set includes the expansion force value F under different ambient temperatures T e The second corresponding data between and the number of cycles a.

[0112] D3, based on a pre-set standard reference number a x And the first functional relationship is obtained at the standard ambient temperature T s When the number of cycles a is the standard reference number a x When the battery has a first standard expansion force value F es1 ;

[0113] Based on a pre-set standard reference number a x and the second corresponding data set to obtain the second standard expansion force value F es2 Set; the second standard expansion force value F es2 The set includes the following conditions at different ambient temperatures T: when the number of cycles a is the standard reference number a x When the second standard expansion force value F corresponding to the battery es2 ;

[0114] Based on the standard ambient temperature T s The corresponding first standard expansion force value F es1 And the second standard expansion force value F corresponding to different ambient temperatures T es2 , obtain a third corresponding data set; the third corresponding data set includes the expansion force difference △F e The third corresponding data between the temperature difference △T; wherein, △F e =F es2 -F es1 , △T=TT s .

[0115] It should be noted that those skilled in the art can consider factors such as the actual application scenario of the battery, the change in the expansion force of the battery at different cycle times, and the like, and adjust the standard reference number a. xThe value of is flexibly set, and this application does not impose any restrictions on this. For example, under different ambient temperatures, when the number of cycles a of the battery is the standard reference number a x When the expansion force values ​​corresponding to the battery fluctuate slightly and are relatively stable, those skilled in the art can consider this point of view and determine the standard reference number a. x , which makes the construction of the expansion force estimation model more accurate.

[0116] D4, based on the third corresponding data set, fitting the expansion force difference ΔF e and the temperature difference ΔT;

[0117] Specifically, the third functional relationship is:

[0118] When the ambient temperature T<T s When △F e =0;

[0119] When the ambient temperature T≥T s When △F e =k2*△T 2 ; and △T=TT s , then △F e =k2*(TT s ) 2 ; Among them, △F e Characterizes the effect of ambient temperature T on expansion force, unit is kN; k2 is the temperature characteristic quantity, unit is kN / ℃ 2 .

[0120] Through step D4, the expansion force difference ΔF is fitted e After the third functional relationship between the temperature difference ΔT and the temperature characteristic value k2 is obtained, the specific value of the temperature characteristic value k2 can be obtained.

[0121] D5, constructing an expansion force estimation model based on the first functional relationship and the third functional relationship;

[0122] Specifically, the expansion force estimation model includes: F e =k1*ln(a)+△F e +m;

[0123] Among them, F e is the expansion force value, the unit is kN; k1 is the cyclic attenuation characteristic, the unit is kN; a is the number of cycles; △F e Characterizes the effect of ambient temperature T on expansion force, the unit is kN; when ambient temperature T<T s When △F e =0, when the ambient temperature T≥T s When △F e=k2*(TT s ) 2 , k2 is the temperature characteristic quantity, the unit is kN / ℃ 2 ;T s is the standard ambient temperature, the unit is ℃; m is the correction value, the unit is kN.

[0124] It should be noted that, in the above steps, when calculating the temperature characteristic quantity k2, the cycle number a is used as the standard reference number a. x When a set of third functional relationships is fitted, the specific value of the temperature characteristic quantity k2 is obtained; of course, those skilled in the art can change the standard reference number a x The value of , select multiple groups of data, and fit different standard reference times a x Under the above conditions, the expansion force difference △F e A third functional relationship between the temperature difference ΔT and the temperature characteristic quantity k2 is obtained, thereby obtaining multiple temperature characteristic quantity k2 values, and then based on the multiple temperature characteristic quantity k2 values, the most accurate temperature characteristic quantity k2 is calculated by taking the average or other methods.

[0125] Therefore, through the above steps D1-D5, the expansion force F is first obtained. e The first functional relationship between the expansion force and the number of cycles a is obtained; then, through the collection and processing of a series of data, the influence of the ambient temperature T on the expansion force is evaluated, and the third functional relationship is obtained. Thus, based on the first functional relationship and the third functional relationship, a more accurate expansion force estimation model is constructed.

[0126] For example, referring to FIG4 , FIG4 shows the expansion force F of the battery under three different ambient temperatures T, namely, the ambient temperatures T are 10° C., 25° C., and 45° C. e The functional relationship between the expansion force F and the number of cycles a is shown in the corresponding functional relationship diagram. e It is positively correlated with the number of cycles a; taking the curve at 25°C as an example, when a < 10, the expansion force F e Satisfies: 0.7kN<F e <1.5kN; when 10≤a<20, expansion force F e Satisfy: 1.5kN≤F e <2kN; when 20≤a<100, expansion force F e Satisfy: 2kN≤F e <3kN; when 100≤a<400, expansion force F e Satisfy: 3kN≤F e <4kN; when 400≤a<1000, expansion force F e Satisfy: 4kN≤F e <4.5kN; when a>1000, expansion force Fe Satisfied: F e >4.5kN. According to Figure 4, when the explosion-proof valve is opened and the battery pressure is released, the battery expansion force F e Will decrease rapidly.

[0127] In a possible implementation, before step S1 acquires the pressure value of the pressure sensor and establishes the initial pressure reference, the following steps are further included:

[0128] E1, controlling the cyclic charge and discharge of the battery, and obtaining the pressure change conditions at various locations on the expanded side of the battery during the cyclic charge and discharge process, to obtain a pressure change cloud diagram of the battery; the expanded side of the battery is the side that bulges when the battery expands;

[0129] E2. Determine the installation position of the pressure sensor on the rigid structure based on the pressure change cloud map.

[0130] For example, referring to Figure 5, the pressure changes at various locations on the expanded side of the battery during the battery's cyclic charge and discharge process are shown. Darker colors indicate greater pressure values. It can be seen that the pressure on this side gradually increases from the edge to the center, with the highest pressure at the center of the battery. Throughout the battery's cyclic charge and discharge process, the battery exhibits the characteristic of increasing pressure closer to the center. Therefore, for this battery, if the pressure sensor is installed at the center of the battery's expanded side, the identification of the battery's explosion-proof valve opening will be more accurate. Of course, the pressure distribution of batteries of different shapes may vary. Those skilled in the art can refer to this method and, for batteries of different shapes, determine the optimal installation position of the pressure sensor on the rigid structure by detecting the pressure at various locations on the battery's expanded side.

[0131] Preferably, the pressure sensor is installed at the center of the rigid structure.

[0132] Therefore, this application uses a pressure sensor and a rigid structure, which are installed in the direction of battery expansion, to obtain the pressure value of the pressure sensor in real time, and through a series of calculations and judgments, to identify whether the battery has a thermal runaway risk. Compared with the existing method of detecting pressure inside the battery, the technical solution of this application does not need to use an air pressure sensor to detect the air pressure inside the battery cell, and avoids the location of the explosion-proof valve. It is directly outside the battery, without destroying the internal structure and parameters of the battery, and without designing a battery vacuum chamber or a confined space. It not only effectively suppresses the expansion of the battery cell, but is also beneficial to the positive and negative electrodes of the battery cell and the diaphragm to maintain the lithium ion channel, and can delay the battery capacity from plummeting; and when the explosion-proof valve is opened, it can sense and warn in time, achieving high-precision identification of battery thermal runaway risks;

[0133] The identification method of the present application can be applied to single-cell, multi-cell or battery modules. When it needs to be applied to the identification of thermal runaway hazards of multiple batteries, it is only necessary to install a rigid structure and a pressure sensor on the outside of the corresponding battery structure to simultaneously identify the thermal runaway hazards of multiple batteries. This is low-cost and more convenient.

[0134] An embodiment of the present application provides a battery thermal runaway hazard identification device, which applies the battery thermal runaway hazard identification method described in the above embodiment; specifically, the device includes a microprogram controller (MCU), a rigid structure, and a pressure sensor; the rigid structure is installed on one side of the battery expansion direction, and the pressure sensor is installed on the side of the rigid structure that is not in contact with the battery, and there is no gap between the pressure sensor and the rigid structure; referring to Figure 6, the MCU is communicatively connected to the pressure sensor; the pressure sensor includes a power cord, which is connected to a power source; the pressure sensor also includes two signal output lines, which are respectively connected to the MCU. Specifically, the device also includes a signal conditioning circuit, and the signal output line is connected to the MCU through the signal conditioning circuit; the pressure sensor also includes a shielding line, which is grounded.

[0135] The MCU is used to execute the system initialization process, which includes system clock initialization, timer initialization, communication interface initialization and analog sampling ADC initialization;

[0136] The MCU is used to obtain the pressure value of the pressure sensor, establish an initial pressure reference, and record the current pressure value of the pressure sensor as the initial pressure value F P0 ;

[0137] The MCU is further configured to: P0 , determine whether the pressure sensor has failed; if so, the MCU issues a pressure sensor failure reminder; if not, the MCU obtains the pressure value of the pressure sensor in real time based on the detection frequency f, and identifies whether the battery has a thermal runaway risk based on the real-time pressure value.

[0138] An embodiment of the present application provides a terminal, including: a processor, a memory, and a communication bus; the communication bus is used to realize connection and communication between the processor and the memory, and the processor is used to execute one or more programs stored in the memory to implement the battery thermal runaway hazard identification method described in the above embodiment.

[0139] An embodiment of the present application provides a computer-readable storage medium storing instructions. When the instructions are executed, the battery thermal runaway hazard identification method described in the above embodiment is executed.

[0140] This is a preferred embodiment of the present application, and does not limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for identifying potential risks of battery thermal runaway, characterized in that: A rigid structure is installed on one side of the battery expansion direction, and a pressure sensor is installed on the side of the rigid structure that does not contact the battery; the pressure sensor is installed at the center of the battery expansion side. The method includes: Obtain the pressure value of the pressure sensor, establish an initial pressure reference, and record the current pressure value of the pressure sensor as the initial pressure value F P0 ; Based on the range of the pressure sensor and the initial pressure value F P0 , determining whether the pressure sensor fails; If so, a warning of pressure sensor failure is issued; If not, then based on the detection frequency f, obtain the pressure value of the pressure sensor in real time, and identify whether the battery has a thermal runaway risk based on the pressure value obtained in real time; The method of obtaining a pressure value of the pressure sensor in real time based on the detection frequency f and identifying whether the battery has a thermal runaway risk based on the pressure value obtained in real time specifically includes: Based on the detection frequency f, a number of detection time nodes are generated, and at each detection time node, the pressure value of the pressure sensor, the cycle number a of the battery, and the ambient temperature T of the battery are obtained in real time; Based on the pressure value of the pressure sensor, a pressure value sequence Q1 is obtained, where Q1={F P1 , F P2 , F P3 ...F Pn }; where n is a natural number, F Pn Indicates the pressure value corresponding to the pressure sensor at the nth detection time node; Based on the cycle number a, the ambient temperature T and the pre-built expansion force estimation model, the expansion force value of the battery is estimated to obtain the expansion force value sequence Q2, Q2 = {F e1 , F e2 , F e3 ...F en }; where n is a natural number, F en Indicates the expansion force value of the battery at the nth detection time node; Based on the pressure value sequence Q1 and the expansion force value sequence Q2, it is determined whether each pressure value in the pressure value sequence Q1 and the corresponding expansion force value in the expansion force value sequence Q2 satisfy the following conditions: Pn ≤F P0 +F en If so, it is determined that the battery has a thermal runaway risk and an early warning is issued; Wherein, the expansion force estimation model includes: F e =k1*ln(a)+△F e +m; F e is the expansion force value, the unit is kN; k1 is the cyclic attenuation characteristic, the unit is kN; a is the number of cycles; △F e Characterizes the effect of ambient temperature T on the expansion force. When ambient temperature T<T s When △F e =0, when the ambient temperature T≥T s When △F e =k2*(TT s ) 2 , k2 is the temperature characteristic quantity, the unit is kN / ℃ 2 ;T s is the standard ambient temperature; m is the correction value, the unit is kN.

2. The method for identifying battery thermal runaway hazards according to claim 1, characterized in that: Before acquiring the pressure value of the pressure sensor in real time based on the detection frequency f, the method further includes: Obtaining operating data of the battery, and determining whether the battery currently has a potential risk event based on the operating data of the battery; If yes, the preset initial detection frequency f1 is adjusted to obtain the detection frequency f; The potential risk events include one or more of the following: a battery short circuit time exceeding a preset short circuit time threshold; a battery overcharge time exceeding a preset overcharge time threshold; and a battery temperature rise rate exceeding a preset temperature rise rate threshold.

3. The method for identifying battery thermal runaway hazards according to claim 1, characterized in that: Based on the detection frequency f, a pressure value of the pressure sensor is acquired in real time, and based on the pressure value acquired in real time, it is identified whether the battery has a thermal runaway risk, specifically including: Sliding window sampling is performed on the pressure value sequence Q1 to obtain a pressure value subsequence Q3 {F Pa , F Pa+1 ...F Pb }; where a and b are both natural numbers, and a<b≤n; Determine whether the data in the pressure value subsequence Q3 are all greater than F Pmax ; If so, it is determined that the pressure sensor is failed and a reminder is issued; wherein, F Pmax is the measuring range of the pressure sensor.

4. The method for identifying battery thermal runaway hazards according to claim 1, characterized in that: Before obtaining the pressure value of the pressure sensor and establishing the initial pressure reference, the method further includes: Controlling the cyclic charge and discharge of the battery, and obtaining the pressure change conditions at various positions on the expansion side of the battery during the cyclic charge and discharge process, to obtain a pressure change cloud diagram of the battery; Based on the pressure change cloud map, the installation position of the pressure sensor on the rigid structure is determined.

5. The method for identifying battery thermal runaway hazards according to claim 1, characterized in that: The pressure value of the pressure sensor is obtained, an initial pressure reference is established, and the current pressure value of the pressure sensor is recorded as the initial pressure value F P0 , specifically including: Obtaining the voltage value output by the pressure sensor, recorded as the initial voltage value V0; Based on the initial voltage value V0, and the range, power supply voltage and sensitivity of the pressure sensor, the initial pressure value F is obtained by calculation. P0 ; The relationship between the pressure value of the pressure sensor and the voltage value output by the pressure sensor is: pressure value / range=(output voltage value / power supply voltage)*sensitivity.

6. A battery thermal runaway hazard identification device, characterized in that: The device includes a microcontroller (MCU), a rigid structure, and a pressure sensor, wherein the MCU is in communication with the pressure sensor; the rigid structure is installed on the side of the battery in the direction of expansion, and the pressure sensor is installed on the side of the rigid structure that does not contact the battery, and the pressure sensor is installed at the center of the battery expansion side; The MCU is used to obtain the pressure value of the pressure sensor, establish an initial pressure reference, and record the current pressure value of the pressure sensor as the initial pressure value F P0 ; The MCU is further configured to: P0 , determine whether the pressure sensor has failed; if so, the MCU issues a pressure sensor failure reminder; if not, the MCU obtains the pressure value of the pressure sensor in real time based on the detection frequency f, and identifies whether the battery has a thermal runaway risk based on the real-time pressure value; The MCU obtains the pressure value of the pressure sensor in real time based on the detection frequency f, and identifies whether the battery has a thermal runaway risk based on the pressure value obtained in real time, specifically including: The MCU generates a number of detection time nodes based on the detection frequency f, and obtains the pressure value of the pressure sensor, the cycle number a of the battery, and the ambient temperature T of the battery in real time at each detection time node; The MCU obtains a pressure value sequence Q1 based on the pressure value of the pressure sensor, where Q1={F P1 , F P2 , F P3 ...F Pn }; where n is a natural number, F Pn Indicates the pressure value corresponding to the pressure sensor at the nth detection time node; The MCU estimates the expansion force value of the battery based on the cycle number a, the ambient temperature T and a pre-built expansion force estimation model, and obtains an expansion force value sequence Q2, where Q2={F e1 , F e2 , F e3 ...F en }; where n is a natural number, F en Indicates the expansion force value of the battery at the nth detection time node; The MCU determines, based on the pressure value sequence Q1 and the expansion force value sequence Q2, whether each pressure value in the pressure value sequence Q1 and the corresponding expansion force value in the expansion force value sequence Q2 satisfy the following conditions: Pn ≤F P0 +F en If so, it is determined that the battery has a thermal runaway risk and an early warning is issued; Wherein, the expansion force estimation model includes: F e =k1*ln(a)+△F e +m; F e is the expansion force value, the unit is kN; k1 is the cyclic attenuation characteristic, the unit is kN; a is the number of cycles; △F e Characterizes the effect of ambient temperature T on the expansion force. When ambient temperature T<T s When △F e =0, when the ambient temperature T≥T s When △F e =k2*(TT s ) 2 , k2 is the temperature characteristic quantity, the unit is kN / ℃ 2 ;T s is the standard ambient temperature; m is the correction value, the unit is kN.

7. A terminal, characterized in that: include: A processor, a memory, and a communication bus; the communication bus is used to realize connection and communication between the processor and the memory, and the processor is used to execute one or more programs stored in the memory to implement the battery thermal runaway hazard identification method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, and when the instructions are executed, the battery thermal runaway hazard identification method according to any one of claims 1 to 5 is executed.

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