Battery pack, vehicle, and monitoring method for thermal runaway thereof

Abstract

To provide a monitoring method for thermal runaway of a battery pack mounted on a vehicle, which allows an occupant to secure a sufficient time to evacuate.SOLUTION: A battery pack 100 includes an assembled battery 10 including a plurality of single cells 11 stacked in sequence, an end plate 20 provided at an end of the assembled battery along the stacking direction of the single cells, a monitoring structure 30 provided on a side parallel to the end plate of at least one of the single cells and configured to monitor the expansion deformation value of the single cell, and a BMS electrically connected to the monitoring structure and configured to calculate a deformation rate and a deformation velocity within a specified time from the expansion deformation value, and to determine whether the battery pack is in a thermal runaway state from the deformation rate and deformation velocity.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] This application claims priority to a Chinese patent application bearing application number 2023116027056, filed with the China Patent Office on November 27, 2023, the entire contents of which are incorporated herein by reference. The present application relates to the technical field of batteries, and in particular to a battery pack, a vehicle, and a method for monitoring thermal runaway thereof. [Background technology]

[0002] Battery packs are a core component of new energy vehicles and provide the energy required to operate the vehicles. During use, a battery pack may experience thermal runaway due to manufacturing defects or extreme conditions such as a strong impact, causing the batteries in the battery pack to expand and deform.

[0003] If a thermal runaway occurs in the battery pack, a thermal runaway warning signal must be sent out 5 minutes before the thermal runaway reaches the vehicle interior, so that passengers have enough time to evacuate to ensure their safety. In general, the method for monitoring the thermal runaway of a battery pack is to monitor the temperature signal or voltage signal. Summary of the Invention [Problem to be solved by the invention]

[0004] When collecting temperature signals in related technology, the NTC (negative temperature coefficient thermistor) that collects the temperature is easily affected by the environment, or when the vehicle travels from a low altitude to a high altitude, the pressure signal also changes significantly, causing false alarms. [Means for solving the problem]

[0005] In a first aspect, the present application provides a battery pack including: an assembled battery including a plurality of single cells stacked in order; an end plate provided at an end of the assembled battery in the stacking direction of the single cells; a monitoring structure provided on a side of at least one of the single cells parallel to the end plate and configured to monitor an expansion deformation value of the single cell; and a BMS electrically connected to the monitoring structure and configured to calculate a deformation rate and a deformation speed within a predetermined time from the expansion deformation value, and to determine whether the battery pack is in a thermal runaway state from the deformation rate and the deformation speed.

[0006] In a second aspect, the present application provides a vehicle including a main body and the battery pack, the battery pack being attached to the main body.

[0007] In a third aspect, the present application provides a battery pack comprising a monitoring structure for acquiring an expansion deformation value ΔL of a battery cell of the battery pack, and a BMS for calculating a deformation rate ε of the battery cell and a deformation speed F(t) within a predetermined time t from the expansion deformation value ΔL; determining whether the deformation rate ε is within a first predetermined range and whether the deformation speed F(t) is within a second predetermined range; If the detected voltage is within these ranges, determining that the battery pack is in a thermal runaway state. Effect of the Invention

[0008] Since a cell in which thermal runaway occurs expands toward the larger surface, a monitoring structure is provided on the side parallel to the end plate of the cell, so that when thermal runaway occurs in the cell, the monitoring structure monitors the expansion deformation value due to the expansion of the cell and transmits the expansion deformation value to the BMS, and the BMS obtains the deformation rate and deformation speed within a predetermined time from the expansion deformation value, determines whether the battery pack is in a thermal runaway state from the deformation rate ε and the deformation speed, and executes the next step of alarm operation if the battery pack is in a thermal runaway state. In this way, by monitoring the expansion deformation value of the cell after expansion when thermal runaway occurs in the cells of the battery pack, providing a basis for determining whether the battery pack is in a thermal runaway state is less susceptible to the influence of the surrounding environment and has higher accuracy compared to a method of monitoring changes in the temperature and pressure of the battery pack. [Brief description of the drawings]

[0009] [Figure 1] 1 is a structural schematic diagram of a battery pack according to an embodiment of the present application. [Diagram 2] 2 is a schematic diagram of the structure of the battery pack in FIG. 1 in a normally used state. [Diagram 3] FIG. 2 is a structural schematic diagram of the battery pack in FIG. 1 in a thermal runaway state. [Figure 4] FIG. 2 is a structural schematic diagram of the unit cell in FIG. 1 in a thermal runaway state. [Diagram 5] FIG. 3 is a structural schematic diagram of the monitoring structure in FIG. 2. [Figure 6] 1 is a schematic flow diagram of a method for monitoring thermal runaway of a battery pack in another embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] As shown in FIGS. 1 to 5, a battery pack 100 according to an embodiment of the present invention includes a battery assembly 10, an end plate 20, a monitoring structure 30, and a BMS (BATTERY MANAGEMENT SYSTEM) 40.

[0011] As shown in Figures 1 to 3, the battery pack 10 includes a plurality of single cells 11 stacked in sequence, an end plate 20 is provided at an end of the battery pack 10 in the stacking direction of the single cells 11, and a monitoring structure 30 is provided on a side parallel to the end plate 20 of at least one of the single cells 11 and configured to monitor an expansion deformation value ΔL of the single cell 11. A BMS 40 is electrically connected to the monitoring structure 30 and configured to calculate a deformation rate ε and a deformation speed F(t) within a predetermined time t from the expansion deformation value ΔL, and to determine whether or not the battery pack 100 is in a thermal runaway state from the deformation rate ε and the deformation speed F(t).

[0012] In the above battery pack 100, since the cell 11 in which thermal runaway occurs expands toward the larger surface, the monitoring structure 30 is provided on the side parallel to the end plate 20 of the cell 11, so that when thermal runaway occurs in the cell 11, the monitoring structure 30 monitors the expansion deformation value ΔL due to the expansion of the cell 11 and transmits the expansion deformation value ΔL to the BMS 40, and the BMS 40 obtains the deformation rate ε and the deformation speed F(t) within a predetermined time from the expansion deformation value ΔL, and judges whether the assembled battery 10 is in a thermal runaway state from the deformation rate ε and the deformation speed F(t), and if it is in a thermal runaway state, executes the next step of alarm operation. In this way, when thermal runaway occurs in the cell 11 of the assembled battery 10, the expansion deformation value ΔL of the cell 11 after expansion is monitored to provide a basis for judging whether the battery pack 100 is in a thermal runaway state, which is less susceptible to the influence of the surrounding environment and has higher accuracy than a method of monitoring changes in the temperature and pressure of the battery pack 100.

[0013] In some embodiments, the cells 11 are prismatic batteries, and when forming the battery pack 100, the prismatic batteries have a side parallel to the end plate 20, which is the larger surface of the prismatic battery, and in a prismatic battery in which thermal runaway occurs, the battery often expands and deforms toward the larger surface, and since this expansion and deformation occurs within an extremely short period of time, the expansion and deformation due to thermal runaway occurring in the cells 11 can be monitored by the monitoring structure 30. The battery management system (BMS) is configured to monitor the state of the battery and prevent overcharging and over-discharging of the battery, thereby extending the service life of the battery, and is also configured to detect a thermal runaway state of the battery, thereby ensuring the safety of the battery during use.

[0014] Specifically, in some embodiments, the monitoring structure 30 includes a gauge 31, which is a device for measuring the distortion of an object and includes an insulating substrate and a metal sensitive grid. When performing a measurement, the gauge 31 is connected to the surface of the object, for example, attached to a large surface of the cell 11 by adhesion. When expansion and deformation occurs in the cell 11 due to thermal runaway, the sensitive grid also deforms, and the resistance value of the sensitive grid changes accordingly. By receiving the minute change in resistance value of the sensitive grid and converting it into an actual distortion value of the cell 11, an expansion and deformation value ΔL of the cell 11 is obtained.

[0015] 5, when the gauge 31 is attached to a large surface of the cell 11, a protrusion is present on a part of the gauge 31 due to the provision of a harness on the gauge 31, for example, due to the position of a solder fillet. In order to avoid damage to the surface of the cell 11 due to this protrusion, in some embodiments, the battery pack 100 further includes an insulating protection member 32, which is covered outside the monitoring structure 30. In this way, the insulating protection member 32 is provided outside the gauge 31, and the insulating protection member 32 covers the protrusion, so that when the gauge 31 is attached to the surface of the cell 11, the position of the protrusion comes into direct contact with the surface of the cell 11, and the risk of breaking the protective film of the cell 11 is avoided.

[0016] Specifically, in some embodiments, the insulating protective member 32 is a mica roll, which is an insulating material made by using mica paper as a base material and glass fiber or ceramic fiber as a reinforcing material, bonding it with a resin, and baking it. A backing adhesive may also be provided on the surface of the mica roll, which allows the gauge 31 to be directly attached to the surface of the battery 11, making it easy to install the gauge 31.

[0017] Specifically, in some embodiments, the range of the total thickness of the gauge 31 and the mica paper covering the outer surface of the gauge 31 is 0.2 mm to 0.3 mm, and making the thickness small in this manner avoids an effect on the installation of the entire battery pack 100, prevents an increase in the length of the battery pack 100 in the stacking direction of the unit cells 11, and keeps the length of the battery pack 100 within an appropriate range. For example, the total thickness of the gauge 31 and the mica paper may be 0.2 mm, 0.22 mm, 0.24 mm, 0.26 mm, 0.28 mm, or 0.3 mm depending on the thickness of the unit cells 11, but is not limited thereto.

[0018] 2 and 3, in some embodiments, when the monitoring structure 30 is disposed in the battery pack 10, in order to ensure the safety of use and the service life of the battery pack 10, the monitoring structure 30 is provided on the cell 11 located at the end of the battery pack 10 in the stacking direction of the cells 11, and on the side of the cell 11 facing the end plate 20. Here, FIG. 2 is a schematic diagram of the battery pack 10 in a normal use state, and FIG. 3 is a schematic diagram of the battery pack 10 in a use state in a thermal runaway state where expansion has occurred.

[0019] Specifically, as shown in Fig. 1, an insulating sheet 50 is also present between the end plate 20 and the battery pack 10, and the monitoring structure 30 is provided between the insulating sheet 50 and the battery pack 10, and thus the monitoring structure 30 is provided at the end of the battery pack 10. This avoids an effect on normal expansion of the entire battery pack 10 during use, ensures the service life of the battery pack 10, and ensures the safety of the battery pack 10 during use. In addition, since the monitoring structure 30 is electrically connected to the BMS 40, providing the monitoring structure 30 at the end of the battery pack 10 reduces the installation cost of the monitoring structure 30 and makes it easy to electrically connect the monitoring structure 30 to the BMS 40 after winding the harness.

[0020] By installing the above-mentioned monitoring structure 30, if a cell 11 in the battery pack 10 expands due to thermal runaway, for example, if a cell 11 in the central region expands, an expansion deformation occurs on a large surface of the cell 11 and is transmitted in sequence to the cells 11 at the end, thereby making it possible to monitor the expansion deformation value ΔL of the cell 11 using the monitoring structure 30 located at the end.

[0021] In some embodiments, in order to more accurately monitor thermal runaway during use of the battery pack 10, the monitoring structure 30 is provided on both of the two single cells 11 at the end of the battery pack 10, and in this way, the expansion of the single cells 11 in the entire battery pack 10 can be monitored, and a control command can be more accurately transmitted by the BMS 40. In some embodiments, the mounting cost of the monitoring structure 30 can be reduced while ensuring normal expansion of the single cells 11. In the stacking direction of the single cells 11, one monitoring structure 30 can be mounted at every 1 / 3 position, one monitoring structure 30 at every 1 / 4 position, or one monitoring structure 30 at every 1 / 5 position. This makes it possible to more accurately monitor the deformation of the single cells 11 after expansion, and also to appropriately reduce the arrangement cost of the monitoring structure 30.

[0022] A unit cell 11 in a normal state of use is as shown in Fig. 1. A unit cell in a state in which expansion has occurred due to thermal runaway is shown by the dashed lines in Figs.

[0023] When determining whether or not thermal runaway has occurred in the battery pack 10 from the deformation rate ε and the deformation rate F(t) according to the expansion deformation value ΔL, for example, as shown in FIG. 4, the original thickness L1 of the cell 11 is 25 mm, and when thermal expansion occurs in the cell 11 within a predetermined time t, for example, within t=3 s, the thickness increases from L1=25 mm to L2=30 mm. For example, the broken lines in FIG. 3 and FIG. 4 indicate a state in which thermal expansion has occurred. At this time, the expansion deformation value ΔL of the cell 11 is 5 mm, the deformation rate ε=(L2-L1) / L1=2%, and the deformation rate F(t)=ε / t=2% / 3≒0.67%. If both the deformation rate value 2% and / or the deformation rate value 0.67% are within the predetermined range of thermal runaway, it indicates that thermal runaway has occurred in the cell 11.

[0024] Specifically, in some embodiments, the ranges of the deformation rate ε and the deformation speed F(t) of the cell 11 in which thermal runaway occurs are set as follows. 2%<ε<8%, and / or 0.4% / s <F(t)<2% / s。 If the deformation rate ε and / or deformation rate F(t) calculated by the BMS 40 from the expansion deformation value ΔL of the single battery 11 monitored by the monitoring structure 30 satisfies the above range, the battery pack 100 is in a thermal runaway state, and the BMS 40 indicates that the next step of alarm operation needs to be performed.

[0025] In the battery pack 100 described above, the assembled battery 10 is provided with a monitoring structure 30, which monitors the expansion deformation value ΔL of the cell 11. This expansion deformation value ΔL is transmitted to the BMS 40, which calculates the deformation rate ε and deformation speed F(t). If both the deformation rate ε and the deformation speed F(t) satisfy the ranges set for the cell 11 in which thermal runaway has occurred, this indicates that thermal runaway has occurred in the cell 11, and in this case, the BMS 40 transmits an alarm signal so that the occupants can safely evacuate.

[0026] As shown in FIG. 6, the thermal runaway monitoring method 200 for the battery pack 100 according to the second embodiment of the present application includes steps S21 to S23. Step S21: The monitoring structure 30 acquires an expansion deformation value ΔL of the cell 11 of the battery pack 100, and calculates the deformation rate ε of the cell 11 and the deformation speed F(t) within a given time t from the expansion deformation value ΔL. If the initial thickness of the cell is L1 and the thickness after expansion during thermal runaway is L2, then the expansion deformation value ΔL=L2-L1, the deformation rate ε of the cell 11=(L2-L1) / L1*100%, and the deformation speed F(t)=ε / t.

[0027] Before this step, the monitoring structure 30 and the battery pack 100 are provided. Here, the battery pack 100 includes the single cells 11 and end plates 20 provided at the ends of the single cells 11 in the stacking direction, and the end plates 20 are provided so as to be parallel to the large faces of the single cells 11. The single cells 11 may be rectangular batteries, and the rectangular batteries may be aluminum shell batteries or secondary batteries such as blade batteries. When thermal expansion occurs in a single cell 11 or in a plurality of single cells 11 of the assembled battery 10, expansion often occurs in the large faces of the single cells 11, and this expansion is transferred between the single cells 11, resulting in expansion in all of the surrounding single cells 11. In this way, the monitoring structure 30 located at the end can monitor the thermal runaway state of the assembled battery 10.

[0028] In some embodiments, the monitoring structure 30 includes a gauge 31 and an insulating protective member 32 that is covered on the outside of the gauge 31. When expansion and deformation occur in the single cell 11 due to thermal runaway, the resistance value of the gauge 31 also changes accordingly. The obtained resistance change amount can be converted into an actual strain value to obtain the expansion and deformation value ΔL of the single cell 11. In addition, in a form in which the insulating protective member 32 is covered on the outside of the gauge 31, a protrusion exists in a part of the gauge 31 due to the provision of a harness, for example, the position of a solder fillet. In order to avoid damage to the surface of the single cell 11 due to this protrusion, in some embodiments, the battery pack 100 further includes an insulating protective member 32, and the insulating protective member 32 is covered on the outside of the monitoring structure 30. In this way, when the gauge 31 is attached to the surface of the single cell 11, the position of the protrusion directly contacts the surface of the single cell 11, and the risk of breaking the protective film of the single cell 11 is avoided.

[0029] Specifically, in some embodiments, the insulating protective member 32 is a mica paper on which a backing glue is provided so that the entire monitoring structure 30 can be conveniently attached to the surface of a battery.

[0030] In some embodiments, prior to measurement, a monitoring structure 30 is attached to at least one cell 11 on a side parallel to the end plate 20 .

[0031] When the monitoring structure 30 is disposed in the battery pack 10, in order to ensure the safety and service life of the battery pack 10, the monitoring structure 30 is provided on the cell 11 located at the end of the battery pack 10 in the stacking direction of the cells 11, and on the side of the cell 11 facing the end plate 20. In order to more accurately monitor thermal runaway during use of the battery pack 10, in some embodiments, the monitoring structure 30 is provided on both of the two cells 11 at the end of the battery pack 10, so that the expansion of the cells 11 in the entire battery pack 10 can be more accurately monitored and the control command can be more accurately transmitted by the BMS 40. In some embodiments, the mounting cost of the monitoring structure 30 can be reduced while ensuring normal expansion of the cells 11. In the stacking direction of the cells 11, one monitoring structure 30 can be mounted at every 1 / 3 position, one monitoring structure 30 at every 1 / 4 position, or one monitoring structure 30 at every 1 / 5 position. This makes it possible to more accurately monitor the deformation of the battery cell 11 after expansion, and also to appropriately reduce the cost of arranging the monitoring structure 30.

[0032] After the battery pack 100 is installed, in this step, the expansion deformation value ΔL of the single battery 11 is obtained by the monitoring structure 30, and the deformation rate ε and the deformation speed F(t) within a predetermined time t are obtained from ΔL, and these can be used to determine the next step.

[0033] The expansion deformation value ΔL in this step refers to the amount of expansion deformation of the cell 11 when the cell 11 actually expands, monitored by the monitoring structure 30. For example, if the original thickness L1 of the cell 11 is 25 mm, the thickness of the cell 11 increases from 25 mm to L2 = 30 mm within a predetermined period, for example, within a predetermined time t = 3 s, in this case, the expansion deformation value ΔL of the cell 11 is 5 mm, the deformation rate ε = (L2 - L1) / L1 = 2%, and the deformation speed F (t) = ε / t = 2% / 3 ≒ 0.67%. If the original thickness L1 of the cell 11 is 25 mm, within a predetermined time t, for example, within a time of t=4 s, the thickness of the cell 11 increases from 25 mm to L2=35 mm. In this case, the expansion deformation value ΔL of the cell 11 is 10, the deformation rate ε=(L2-L1) / L1=10 / 25=4%, and the deformation rate F(t)=ε / t=4% / 4≒1% / s. If either of these two is within the respective predetermined ranges, it indicates that the battery pack 100 is in a thermal runaway state. In order to ensure the accuracy of the judgment, it is necessary to obtain the deformation rate F(t) in addition to the deformation rate ε. This is because, in the process of normal use, the cell 11 also expands due to its own heat generation due to the influence of the environment or long-term use, and if only the deformation rate ε is monitored, there is a possibility of misjudgment. When thermal runaway occurs in the single cell 11, expansion occurs within a short time, and if the deformation rate F(t) satisfies a preset condition as a result of monitoring, both the deformation rate ε and the deformation rate F(t) are used as the basis for judgment in the subsequent steps. This makes it possible to more accurately judge whether or not a thermal runaway state has occurred, and to avoid erroneous judgment.

[0034] Step S22: It is determined whether the deformation rate ε is within a first predetermined range and whether the deformation speed F(t) is within a second predetermined range.

[0035] After obtaining the deformation rate ε and deformation speed F(t) of the cell 11 in the previous step, in this step, a judgment is made for a predetermined range.

[0036] Specifically, the first predetermined range is 2%<ε<8% and / or the second predetermined range is 0.4% / s <F(t)<2% / sである。

[0037] Step S23: If it is within these predetermined ranges, it indicates that the battery pack is in a thermal runaway state.

[0038] In the above step, when the value of the obtained strain ε is within the range of 2% < ε < 8%, and / or the value of the obtained strain rate F(t) is within the range of 0.4% / s < F(t) < 2% / s, it indicates that the battery pack 100 is in a thermal runaway state.

[0039] The thicknesses of the prismatic batteries are various. The larger the thickness of the prismatic battery, the larger its deformation amount. Therefore, the deformation range is set to 2% < ε < 8%, and the strain rate is set to 0.4% / s < F(t) < 2% / s. If either the range of ε or the range of F(t) is within the above predetermined range, there is a single cell 11 in the battery pack 100 where thermal runaway has occurred. At this time, it indicates that the battery pack 100 is in a thermal runaway state. If both of these ranges are within the above predetermined range, it is possible to accurately determine that the battery pack 100 is in a thermal runaway state and reduce the possibility of misjudgment.

[0040] For example, in the two examples listed above, ε = 2%, F(t) ≈ 0.67% is within the ranges of 2% < ε < 8% and 0.4% / s < F(t) < 2% / s, and ε = 4%, F(t) = 1% is within the ranges of 2% < ε < 8% and 0.4% / s < F(t) < 2% / s. Therefore, it indicates that the battery pack 100 is in a thermal runaway state.

[0041] To ensure the accuracy of the determination, before the step of obtaining the strain ε of the single cell 11 and the strain rate F(t) within the predetermined time t by the monitoring structure 30, the method for monitoring thermal runaway of the battery pack 100 includes the step of obtaining the voltage and temperature of the battery pack 100, and the step of determining whether the ratio x of the voltage drop value within the predetermined period t' of the voltage to the initial voltage value is within a third predetermined range, and whether the temperature rise rate y within the predetermined period t' of the temperature is within a fourth predetermined range, and If it is within these ranges, the method further includes a step of acquiring the expansion deformation value ΔL of the cell (11) by the monitoring structure (30).

[0042] In order to avoid erroneous judgment, before obtaining the values ​​of the deformation rate ε and the deformation speed F(t), it is necessary to obtain the internal voltage and temperature of the battery pack 100, and determine whether the voltage drop value and temperature rise rate within a specified period t' of the voltage and temperature are within their respective specified ranges. Only if the voltage drop value and temperature rise rate within the specified period t' of the voltage and temperature also satisfy the conditions, is the subsequent step of obtaining the expansion deformation value ΔL of the single cell 11, thereby ensuring the accuracy of the judgment that the battery pack 100 is in a thermal runaway state.

[0043] Here, if the initial voltage value of the battery pack is V1 and the voltage value at the specified period t' is V2, then the voltage drop value ΔV = (V2-V1) and the ratio of the voltage drop value to the initial voltage value x = ΔV / V1*100%. If the initial temperature of the battery pack is T1 and the temperature at the specified period t' is T2, then the temperature rise rate y = (T2-T1) / t*100%.

[0044] Specifically, in some embodiments, the predetermined period t' is 3 s or more, the third predetermined range is the range x of the voltage drop value that is 25% or more, and the fourth predetermined range is the heating rate y that is 1° C. / s or more.

[0045] For example, when the initial voltage value V1 of the battery pack 100 is 100v, when the voltage value drops to V2=70v, the voltage drop value ΔV=V2-V1=100-70=30v, and the voltage drop value x=30 / 100*100%=30%, which satisfies the third predetermined range because 30%>25%. Also, when the initial temperature T1 of the battery pack 100 is 60, the temperature of the battery pack 100 reaches T2=70°C within a period of t'=3s, and at this time, the temperature rise rate=(T2-T1) / t*100%=10 / 3=3.33°C / s, which is within the fourth predetermined range, and in this case, both the voltage drop value and the temperature rise rate of the battery pack 100 are within their respective predetermined ranges. When judged in combination with the deformation rate ε and the deformation rate F(t) in some embodiments, the accuracy of judging that the battery pack 100 is in a thermal runaway state can be improved and erroneous judgment can be avoided.

[0046] In addition, when monitoring thermal runaway of the battery pack 100 using the thermal runaway monitoring method of the battery pack 100 in some embodiments, if the cell 11 is in a high state of charge (SOC) or low state of health (SOH), the cell 11 becomes swollen due to repeated gas generation, and at this time, the risk of thermal runaway of the cell 11 increases. Therefore, the gauge 31 can more accurately monitor thermal runaway of the cell 11 at the end of battery life (EOL: End of Line), and can avoid false alarms.

[0047] In another embodiment of the present application, a vehicle is also provided, which includes a main body and the above-mentioned battery pack 100, wherein the battery pack 100 is attached to the main body.

[0048] In the above vehicle, a monitoring structure 30 is provided in a battery pack attached to a main body, the monitoring structure 30 acquires a deformation amount ΔL of a battery pack cell 11, the expansion deformation value ΔL is transmitted to the BMS 40, the BMS 40 acquires a deformation rate ε and a deformation speed F(t) within a predetermined time from the expansion deformation value ΔL, the BMS 40 judges whether the battery pack 100 is in a thermal runaway state from the deformation rate ε and the deformation speed F(t), and if the battery pack 100 is in a thermal runaway state, the BMS 40 executes an alarm operation of the next step. In this way, by monitoring the expansion deformation value ΔL of the expanded battery 11 when thermal runaway occurs in the battery pack 100 cell 11, a basis for judging whether the battery pack 100 is in a thermal runaway state is provided, which is less susceptible to the influence of the surrounding environment, has high accuracy, and improves the safety of use during use of the vehicle, compared to a method of monitoring changes in temperature and pressure of the battery pack 100. [Explanation of symbols]

[0049] 100 Battery Packs 10 Battery pack 11 Battery 20 End plate 30 Monitoring Structure 31 Gauge 32 Insulating and protective materials 40 BMS (Battery Management System) 50 Insulation sheet

Claims

1. A battery pack (100), A battery pack (10) including a plurality of unit cells (11) stacked in order; an end plate (20) provided at an end of the battery pack (10) in the stacking direction of the cells (11); a monitoring structure (30) provided on a side of at least one of the cells (11) parallel to the end plate (20), and configured to monitor an expansion deformation value of the cell (11); and a BMS (40) electrically connected to the monitoring structure (30) and configured to calculate a deformation rate and a deformation speed within a predetermined time from the expansion deformation value, and to determine whether the battery pack (100) is in a thermal runaway state from the deformation rate and the deformation speed.

2. The battery pack (100) of claim 1, wherein the monitoring structure (30) includes a gauge (31).

3. 3. The battery pack (100) according to claim 2, wherein the monitoring structure (30) further includes an insulating protective member (32), the insulating protective member (32) being covered outside the gauge (31).

4. The battery pack (100) according to any one of claims 1 to 3, wherein in a stacking direction of the cells (11), the monitoring structure (30) is provided on the cell (11) located at an end of the battery pack (10), and on a side of the cell (11) facing the end plate (20).

5. The battery pack (100) according to claim 4, wherein the monitoring structure (30) is provided on each of the cells (11) at two ends of the battery assembly (10) in the stacking direction of the cells (11).

6. The battery pack (100) according to any one of claims 1 to 3 or 5, wherein the monitoring structure (30) has a thickness range of 0.2 mm to 0.3 mm in the stacking direction of the cells (11).

7. A vehicle, A vehicle comprising: a main body; and a battery pack (100) according to any one of claims 1 to 3 or 5, the battery pack (100) being attached to the main body.

8. A thermal runaway monitoring method, comprising: acquiring an expansion deformation value ΔL of a cell (11) of the battery pack (100) by a monitoring structure (30), and calculating a deformation rate ε of the cell (11) and a deformation speed F(t) within a predetermined time t from the expansion deformation value ΔL by a BMS (40); determining whether the deformation rate ε is within a first predetermined range and whether the deformation speed F(t) is within a second predetermined range; If the battery pack (100) is within these ranges, determining that the battery pack (100) is in a thermal runaway state.

9. The thermal runaway monitoring method according to claim 8, wherein, when an initial thickness of the battery (11) is L1 and a thickness after expansion during thermal runaway is L2, an expansion deformation value ΔL=L2-L1, a deformation rate ε of the battery (11)=(L2-L10) / L1*100%, and a deformation speed F(t) within a predetermined time t=ε / t.

10. the first predetermined range is 2%<ε<8%, and / or 9. The method of claim 8, wherein the second predetermined range is 0.4% / s<F(t)<2% / s.

11. Prior to the step of acquiring an expansion deformation value ΔL of the cell (11) by the monitoring structure (30) and calculating a deformation rate ε of the cell (11) and a deformation speed F(t) within a predetermined time t from the expansion deformation value ΔL, the thermal runaway monitoring method for the battery pack (100) includes the steps of: acquiring a voltage and a temperature of the battery pack (100); determining whether a ratio x of a voltage drop value within a predetermined period t' to an initial voltage value of the voltage is within a third predetermined range, and whether a temperature rise rate y within the predetermined period t' is within a fourth predetermined range; The thermal runaway monitoring method according to any one of claims 8 to 10, further comprising the step of executing the step of acquiring the expansion deformation value ΔL of the single battery (11) by a monitoring structure (30) if it is within these ranges.

12. The predetermined period t' is 3 seconds or more, The third predetermined range x is equal to or greater than 25%; The thermal runaway monitoring method according to claim 11 , wherein the fourth predetermined range y is equal to or greater than 1° C. / s.

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