CN111948543A - Thermal runaway chain reaction judgment system and method for energy storage battery pack - Google Patents

Abstract

The invention discloses a thermal runaway chain reaction judgment system and method for an energy storage battery pack. According to the thought, a battery thermal runaway test is designed, so that the triggered power and energy, and the released power and energy can be quantitatively embodied; in the testing process, two factors of direct heating of the adjacent batteries on the contact surfaces and indirect heating of smoke on the side surfaces of the adjacent batteries are considered, so that the design is closer to the actual situation. When the power and the energy of indirect flue gas heating of the adjacent side batteries are finally calculated, the difference between the actual battery module and the test battery is considered, the number of the batteries in the actual battery module is large, and the flue gas heating effect is dispersed, so that an n/3 treatment mode is introduced.

Description

An energy storage battery pack thermal runaway chain reaction judgment system and method

【Technical field】

The invention belongs to the technical field of battery pack thermal runaway judgment, and relates to a system and method for judging a thermal runaway chain reaction of an energy storage battery pack.

【Background technique】

In recent years, there have been many fire accidents in lithium-ion battery energy storage power stations, especially in South Korea, where a total of 29 fire accidents have occurred so far. The safety of energy storage batteries has attracted great attention both inside and outside the industry. Because the materials used in lithium-ion energy storage batteries are flammable substances, such as the electrolyte is flammable organic electrolyte, the separator and graphite negative electrode are also flammable, and the energy storage battery will undergo thermal runaway reactions under abuse conditions. The lithium-ion energy storage battery has potential safety risks. When the lithium-ion energy storage battery is in an abnormal working state (overcharge, overheating, etc.), it will cause a thermal runaway reaction of the lithium-ion energy storage battery, which may lead to fire and combustion. Even explosions and other safety accidents. The so-called thermal runaway means that after the energy storage battery is stimulated by an external excitation source, complex physical, chemical and electrochemical side reactions occur inside the battery. These side reactions often have an exothermic effect, and the exothermic effect will further increase the temperature of the battery until the inside of the battery. A large-scale exothermic side reaction occurs. At this time, the performance of the battery is that the surface temperature of the battery will rise rapidly (approximately a linear rise). In some cases, it will ignite and then burn violently.

It can be seen from the accident reports of battery energy storage power stations that have occurred and related research literature that after thermal runaway occurs in individual batteries in lithium-ion energy storage power stations, a chain reaction of thermal runaway will further form, that is, thermal runaway of individual batteries will cause The thermal runaway of adjacent batteries has occurred one after another, causing a global fire accident. The reason for the triggering of this thermal runaway chain reaction is that the external energy shock received by the battery exceeds the triggering critical condition of the thermal runaway reaction of the battery itself, and the energy released by the thermal runaway of the battery exceeds the critical energy that triggers the thermal runaway reaction of the battery. .

In order to improve the safety of energy storage power stations, it is necessary to take various measures to prevent the thermal runaway chain reaction of lithium-ion energy storage batteries, or to take comprehensive protection according to the severity of the thermal runaway chain reaction of lithium-ion energy storage batteries. measures to curb the speed and intensity of its thermal runaway chain reaction. This requires a judgment on the critical conditions for the thermal runaway chain reaction of lithium-ion energy storage batteries, and only in this way can targeted protective measures be taken. When the critical energy of the reaction is prone to occur, or a thermal runaway chain reaction is likely to occur, it is necessary to strengthen the design of the corresponding protective structure design and protective measures, and the configuration of the fire protection system also needs to strengthen the dosage and injection requirements of the fire extinguishing agent; When it is judged that the energy released by the thermal runaway of the battery is insufficient to trigger the critical energy of the thermal runaway reaction of the battery, it is unlikely to occur, or the possibility is low, then the conventional protection design and conventional fire extinguishing configuration may be adopted to meet the requirements.

Therefore, the quantitative judgment method for the critical conditions of thermal runaway chain reaction of lithium-ion energy storage batteries is of great significance for improving the safety of energy storage power stations and optimizing the design of safety protection measures for energy storage systems. However, there is still a lack of corresponding judgment methods and judgment means. The current conventional practice is to directly stimulate one of the lithium-ion energy storage battery packs or modules through an external excitation source to make one of the batteries thermally out of control, and then observe whether a chain reaction occurs. This method has high test costs and high risk in the test process. , Moreover, the handling of the battery pack or module after the test also has potential safety hazards, because the tested battery has been damaged internally, but the appearance may still be normal, and it is difficult to visually judge whether the battery has a problem, which gives the test Handling brings great security risks. The most important thing is that this method can only judge whether a chain reaction occurs from the phenomenon, and it cannot determine the critical conditions of the chain reaction, so it cannot provide a quantitative basis for the thermal management of the battery, the protection design, and the design of the fire extinguishing system. For example, through the battery pack test, it is observed that the battery has a thermal runaway chain reaction. If the method of forced heat dissipation to reduce the temperature is considered to suppress thermal runaway, then how much heat dissipation power or how much cooling effect the battery can achieve can suppress thermal runaway , it is impossible to give these data with reference value through the existing technology.

In the prior art, the method of testing, such as overcharging or heating a battery in the battery pack, is used to actually judge whether a thermal runaway chain reaction will occur through a pressure test.

Although this method is simple and effective, it cannot extract the critical conditions for the thermal runaway chain reaction of the battery, that is, the judgment basis, that is, this method is only for a specific battery pack, when the same battery is used, it is replaced by another After the battery module is replaced with other battery modules, the experiment of thermal runaway chain reaction needs to be done again. Moreover, this method can only see whether a chain reaction has occurred, and cannot provide a basis for the design of the battery, the design of the battery pack, the design of the safety protection structure and the heat dissipation design of the system.

[Content of the invention]

The purpose of the present invention is to solve the problems in the prior art, and to provide a system and method for judging the thermal runaway chain reaction of an energy storage battery pack. Provide reference and basis for energy system design and energy storage power station safety management.

To achieve the above object, the present invention adopts the following technical solutions to realize:

A method for judging a thermal runaway chain reaction of an energy storage battery pack, comprising the following steps:

Calculate the energy required for overcharging to trigger thermal runaway of one cell in the battery pack;

Calculate the energy released after the battery is triggered by overcharge and thermal runaway;

Determine whether a thermal runaway chain reaction occurs in the battery pack;

Under a certain overcharge power, when the energy required for thermal runaway caused by overcharge of the battery ≥ the energy released after the thermal runaway caused by overcharge of the battery is triggered, then the battery under the overcharge power: no thermal runaway chain reaction will occur; Otherwise, the battery is at this overcharge power: a thermal runaway chain reaction will occur.

A further improvement of the above method is:

In the step 1, the specific method for calculating the energy required for overcharging to trigger the thermal runaway of the battery is as follows:

Step 1-1, fully charge the battery according to the battery's factory operating instructions;

Step 1-2, put the 3 batteries close to each other, set up a temperature measuring device with a thickness of 1-10mm between the batteries and on the side where the batteries are in contact with the air; the outer sides of the two outermost batteries are close to one another Layer high thermal resistance material;

Steps 1-3, using a variety of powers to conduct an overcharge test on the battery, the power range is from 0.1P ₀ to 10P ₀ , where P ₀ is the rated power of the battery;

Steps 1-4, record the moment when the battery thermal runaway occurs, and calculate the overcharged energy E:

E=∫f(P ₁ )dt

Among them, P ₁ is the power of overcharging, and t is the time of overcharging;

Steps 1-5, when the battery power is reduced to a certain value, the battery will not suffer from thermal runaway, and this value is the minimum power P _min at which thermal runaway of the battery occurs;

Steps 1-6, draw the battery surface temperature-time curve in the overcharge experiment;

Steps 1-7, draw the power-energy curve for charging the battery, the curve represents the threshold value of thermal runaway triggered by the battery under the overcharge condition, the upper part of the curve represents that the battery has undergone thermal runaway, and the lower part of the curve represents that the battery has not undergone thermal runaway.

In the step 2, the specific method for calculating the energy released after the battery is triggered by overcharging and thermal runaway is as follows:

Step 2-1, when performing steps 1-3, record the temperature between the batteries on both sides of the overcharged battery, and draw the surface temperature-time curve of the overcharged battery;

Step 2-2, compare the battery surface temperature-time curve drawn in step 1-6, find the battery surface temperature-time curve corresponding to the closest heating test, estimate the overcharged battery surface heating power P ₂ , and calculate accordingly. Thermal energy Q ₁ on the surface of the overcharged battery:

Q ₁ =∫f(P ₂ )dt

The heating energy is the heating energy of the contact surface of the adjacent battery;

Step 2-3, draw the temperature-time curve of the side of the adjacent battery in contact with the air; find the battery surface temperature-time curve corresponding to the closest heating test, estimate the heating power P ₃ of the flue gas to the adjacent battery, and According to this, the heating energy Q ₂ is calculated:

Q ₂ =∫f(P ₃ )dt

The heating energy Q ₂ is the heating energy of the contact surface between the adjacent battery and the air;

Steps 2-4, calculate the energy Q released after the battery overcharge and thermal runaway are triggered:

Among them, n is the battery module of the battery group, or the number of batteries in the battery box.

The step 3 is specifically:

When E≥Q, the battery will not have a thermal runaway chain reaction under the overcharge power;

When E<Q, the battery will have a thermal runaway chain reaction under the overcharge power.

An energy storage battery pack thermal runaway chain reaction judgment system, comprising:

The overcharge energy calculation module for thermal runaway caused by battery overcharge is used to calculate the overcharge energy when the battery is thermally runaway;

The released energy calculation module for thermal runaway caused by battery overcharge is used to calculate the released energy after battery thermal runaway;

The judgment module is used to judge whether the thermal runaway chain reaction occurs in the battery according to the overcharge energy and the released energy.

A test device comprising:

A test box, in which there are 3 batteries, including an overcharged battery, and adjacent batteries arranged on both sides of the battery; the distances between the 3 batteries and the top, sides, and front and rear of the inside of the box body of the test box are consistent with the distance between the battery in the battery module and its box;

a temperature measuring device, the temperature measuring device comprising a first temperature sensor disposed between the batteries and a second temperature sensor on the side of the battery in contact with the air;

a thermal resistance layer, the thermal resistance layer is arranged on the outer sides of the two outermost batteries;

The upper computer, which is connected with the temperature measuring device, has a built-in system for judging the thermal runaway chain reaction of the energy storage battery pack according to claim 5 .

A further improvement of the above-mentioned test device is:

A third temperature sensor is also arranged above the safety valve of the battery for recording the open flame temperature of the combustion gas-liquid mixture ejected during the thermal runaway.

The thickness of the first temperature sensor and the second temperature sensor is 1-10 mm.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention provides the basis for whether a chain reaction occurs in the battery approximately quantitatively, and the relevant values and judgment steps can be used as the basis for the design of battery safety protection, such as in the thermal management of the battery; the heating power of the battery calculated by the present invention and The energy can be used for the heat dissipation design of the battery, and the heating power and energy of the battery can be lower than the critical condition of the battery thermal runaway through heat dissipation, or thermal protection materials are introduced in the battery safety design; the battery thermal runaway heating power calculated by the present invention and energy, to design the thermal protection parameter index that the thermal protection material needs to meet, or when designing the battery fire protection system; the thermal runaway heating power and energy of the battery calculated by the present invention are used to design how much cooling and extinguishing medium to be used, so as to calculate the required configuration. Extinguishing dose.

【Description of drawings】

In order to describe the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of a battery module, wherein (a) is a front view, and (b) is a top view;

Fig. 2 is the structural representation of the test box of the present invention, wherein (a) is a front view, and (b) is a top view;

Fig. 3 is the structural schematic diagram of the battery pack in the test box of the present invention;

Figure 4 is a power-energy curve for battery charging.

Wherein: 1-battery module; 2-test box; 3-first temperature sensor; 4-second temperature sensor; 5-thermal resistance layer.

【Detailed ways】

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inside", etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings , or the orientation or positional relationship that the product of the invention is usually placed in use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed in a specific orientation and operation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are only used to differentiate the description and should not be construed to indicate or imply relative importance.

Furthermore, the presence of the term "horizontal" does not imply that the component is required to be absolutely horizontal, but rather may be tilted slightly. For example, "horizontal" only means that its direction is more horizontal than "vertical", it does not mean that the structure must be completely horizontal, but can be slightly inclined.

In the description of the embodiments of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. It can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

Below in conjunction with accompanying drawing, the present invention is described in further detail:

The invention discloses a method for judging a thermal runaway chain reaction of an energy storage battery pack, comprising the following steps:

1. Calculate the energy required for overcharging to trigger thermal runaway of the battery:

1.0 The test environment is a semi-closed test box 2. The test box is designed as follows: the distance between the box and the battery is consistent with the distance between the box of the battery module 1 and the battery in the module; the vent size of the test box is the same as that of the battery module box. The size of the body vents is proportionally reduced according to the number of batteries; as shown in Figure 1 and Figure 2, Figure 1 is the front view and top view of the battery module, and Figure 2 is the front view and top view of the test box, in which the test cells in the test box and The distance between the upper, left, right, front and rear of the box should be consistent with the distance between the battery in the battery module and the box.

1.1 Fully charge the battery according to the battery's factory operating instructions, and set it aside for 12 hours;

1.2 Adhere the above three test cells to each other, as shown in Figure 3, set a first temperature sensor 3 between the test cells, and set a second temperature sensor 4 on the side of the test cell in contact with the air, with a thickness of 1- 10mm; the outer sides of the outermost two batteries (the side with the largest surface area) are closely attached to a thermal resistance layer 5, and the thermal resistance layer is made of high thermal resistance materials, such as ultra-fine glass wool, high silica wool, vacuum insulation Hot plate, aerogel, foam, foam, polyurethane, etc.; avoid the outer side of the battery from contacting the air, more specifically, avoid contact with the flue gas after the battery thermal runaway, and prevent the outer side from being heated by the flue gas ;

1.3 Use a variety of powers to test the battery for overcharging, the power range is from 0.1P ₀ to 10P ₀ , where P ₀ is the rated power of the battery;

1.4 Record the moment when the battery thermal runaway occurs, and calculate the overcharged energy E:

E=∫f(P ₁ )dt

Among them, P ₁ is the power of overcharging, and t is the time of overcharging;

1.5 When the battery power is reduced to a certain value, the battery will not have thermal runaway, and this value represents the minimum power P _min at which thermal runaway of the battery occurs;

1.6 Draw the battery surface temperature-time curve in the overcharge experiment;

1.7 Draw the power-energy curve for charging the battery. The curve represents the critical value of the battery that triggers thermal runaway under overcharge conditions, that is, the energy values corresponding to different powers required to trigger thermal runaway of the battery. The upper part of the curve represents that the battery has undergone thermal runaway. The lower part of the curve represents that the battery has not experienced thermal runaway.

2. Calculate the energy released after the battery is triggered by overcharge and thermal runaway:

2.1 During the operation in step 1.3, record the temperature between the batteries on both sides of the overcharged battery, and draw the surface temperature-time curve of the overcharged battery;

2.2 Compare the battery surface temperature-time curve in step 1.6, find the battery surface temperature-time curve corresponding to the heating test that is close to it, estimate the surface heating power of the overcharged battery, and calculate the surface heating of the overcharged battery accordingly. The energy Q ₁ :

Q ₁ =∫f(P ₂ )dt

The heating energy is the heating energy of the contact surface of the adjacent battery;

2.3 During the operation in step 1.3, set a temperature measuring device above the battery safety valve to record the gas-liquid mixture ejected during the thermal runaway process. If the gas-liquid mixture burns after the gas-liquid mixture is ejected, the record is the temperature of the open flame;

2.4 Draw the temperature-time curve recorded by the temperature measuring device on the side of the adjacent battery in contact with the air; find the battery surface temperature-time curve corresponding to the heating test close to it, and estimate the heating power P of the flue gas to the adjacent battery ₃ , that is, the heating power of the adjacent battery and the air (flue gas) contact side, and calculate the heating energy Q ₂ accordingly:

Q ₂ =∫f(P ₃ )dt

This heating energy Q ₂ is the heating energy of the contact surface between the adjacent battery and the air;

2.5 Consider the number of battery modules in the battery group, or the number of batteries in the battery box, denoted as n;

2.6 Calculate the energy Q released after the battery overcharge and thermal runaway are triggered:

The sum is the heating energy to the adjacent battery after the overcharged battery thermally runaway.

3. Determine whether the battery has a thermal runaway chain reaction

3.1 Under a certain overcharge power, when the energy of the battery overcharge caused runaway ≥ the energy released by the thermal runaway caused by the battery overcharge, it is judged that the battery will not have a thermal runaway chain reaction under this overcharge power;

3.2 Under a certain overcharge power, when the energy released by the battery overcharge caused runaway < the energy released by the thermal runaway caused by the battery overcharge, it is judged that the battery will have a thermal runaway chain reaction under this overcharge power.

The invention also discloses an energy storage battery pack thermal runaway chain reaction judgment system, comprising an overcharge energy calculation module for thermal runaway caused by battery overcharge, a released energy calculation module for thermal runaway caused by battery overcharge, and a judgment module. Among them, the overcharge energy calculation module for thermal runaway caused by battery overcharge is used to calculate the overcharge energy when the battery is thermally runaway; the energy release calculation module for thermal runaway caused by battery overcharge is used to calculate the released energy after battery thermal runaway; The judgment module is used to judge whether the thermal runaway chain reaction occurs in the battery according to the overcharge energy and the released energy.

In order to realize the above test method, the present invention also provides a test device, which includes a test box, a temperature measurement device, a thermal resistance layer and an upper computer. The test box is provided with 3 batteries, and the distance between the top, both sides, and front and rear of the battery and the inside of the test box is consistent with the distance between the battery in the battery module and its box; the temperature measurement device includes a set of The first temperature sensor between the battery and the battery, the second temperature sensor on the side of the battery in contact with the air, and the third temperature sensor arranged above the battery safety valve, the thickness of the first temperature sensor and the second temperature sensor is 1-10mm, the third temperature sensor is used to record the open flame temperature of the combustion gas-liquid mixture ejected during the thermal runaway process; the thermal resistance layer is arranged on the outer sides of the two outermost batteries; the upper computer and the The temperature measurement device is connected, and the above-mentioned thermal runaway chain reaction judgment system of the energy storage battery pack is built in.

Principle of the present invention:

Batteries undergo thermal runaway reactions under overcharged and overheated conditions, releasing a large amount of heat, which heats adjacent cells, potentially triggering thermal runaway of adjacent cells as well.

Whether a chain reaction of thermal runaway reaction occurs, the key lies in judging the relationship between the power and energy required to trigger the thermal runaway of the battery and the power and energy released by the battery after thermal runaway. If the thermal power and energy released by the battery after thermal runaway are greater than the power and energy required to trigger the thermal runaway of the battery, that is, the energy released by the battery is more than the energy absorbed by the battery, thermal runaway will occur, otherwise thermal runaway will not occur. The energy passively absorbed by the battery includes electrical energy and thermal energy, and the energy released after the thermal runaway of the battery is the energy generated by the internal thermal runaway side reaction of the battery (chemical energy and reaction heat) converted from the electrical energy and thermal energy absorbed before the thermal runaway of the battery. ), there is no clear size relationship between the two.

The invention is based on the thermal balance principle of battery heating and heat release. When the received energy exceeds the critical condition of thermal runaway, the battery thermally runs out of control and releases energy. When the energy released by the battery thermal runaway is greater than the received energy required to trigger thermal runaway, thermal runaway occurs. chain reaction. According to this idea, the battery thermal runaway test is designed, so that the triggered power, energy, and released power and energy can be quantified and reflected;

During the test, two factors were considered, namely, the direct heating of the adjacent cells at the contact surface and the indirect heating of the fume from the side of the adjacent cells, so that the design was closer to the actual situation.

In the final calculation of the power and energy of the indirect flue gas heating of the adjacent side cells, the difference between the actual battery module and the test battery was considered. There are many batteries in the actual battery module, and the effect of flue gas heating is scattered. Therefore, n/ 3 processing methods.

The present invention also has the following advantages:

The invention determines the critical condition of battery thermal runaway through multiple power overcharge tests, and determines the energy released in the entire process of battery thermal runaway through the temperature changes of adjacent batteries and flue gas in the overcharge test. The invention judges whether a chain reaction will occur in the battery by comparing the power and energy received by the battery with the power and energy released by the thermal runaway of the battery.

By introducing a method for judging the heating power of the side battery temperature in contact with the air, the present invention comprehensively considers the heating path of the surrounding batteries after the thermal runaway of the battery in the battery pack. The heat is transferred by the way the flue gas contacts the side, which is closer to the real situation.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. The method for judging the thermal runaway chain reaction of the energy storage battery pack is characterized by comprising the following steps of:

calculating the energy required by one battery in the battery pack for triggering thermal runaway of the battery pack due to overcharge;

calculating the energy released after the battery overcharge thermal runaway trigger;

judging whether the battery pack has thermal runaway chain reaction;

under a certain overcharge power, when the energy required by the battery for causing thermal runaway due to overcharge is more than or equal to the energy released after the battery is triggered by causing thermal runaway due to overcharge, the battery is under the overcharge power: thermal runaway chain reaction can not occur; otherwise, the battery at the overcharge power: a thermal runaway chain reaction may occur.

2. The method for judging the thermal runaway chain reaction of the energy storage battery pack according to claim 1, wherein in the step 1, a specific method for calculating the energy required by the thermal runaway of the battery triggered by the overcharge is as follows:

step 1-1, fully charging the battery according to the operation instruction of battery delivery;

step 1-2, closely attaching 3 batteries to each other, and arranging a temperature measuring device with the thickness of 1-10mm between the batteries and on the side surface of the battery, which is in contact with air; the outer sides of the two batteries at the outermost side are tightly attached with a layer of high thermal resistance material;

step 1-3, overcharge testing was performed on the cells using various powers ranging from 0.1P₀～10P₀In which P is₀Is the rated power of the battery;

step 1-4, recording the moment when the thermal runaway of the battery occurs, and calculating the overcharged energy E:

E＝∫f(P₁)dt

wherein, P₁Is the power of overcharge, t is the time of overcharge;

step 1-5, when the battery power is reduced to a certain value, the battery can not generate thermal runaway, and the value is the minimum power P generated by the thermal runaway of the battery_min；

Step 1-6, drawing a battery surface temperature-time curve in an overcharge experiment;

and 1-7, drawing a power-energy curve for charging the battery, wherein the curve represents a critical value of the battery for triggering thermal runaway under an overcharge condition, the upper part of the curve represents that the thermal runaway of the battery occurs, and the lower part of the curve represents that the thermal runaway of the battery does not occur.

3. The method for judging the thermal runaway chain reaction of the energy storage battery pack according to claim 2, wherein in the step 2, a specific method for calculating the energy released after the battery overcharge thermal runaway trigger is as follows:

step 2-1, recording the temperature between the batteries at two sides of the overcharged battery when the step 1-3 is executed, and drawing a surface temperature-time curve of the overcharged battery;

step 2-2, comparing the battery surface temperature-time curves drawn in the step 1-6, searching the battery surface temperature-time curve corresponding to the closest heating test, and estimating the overcharged battery surface heating power P₂And calculating the heat generation energy Q of the overcharged battery surface based thereon₁：

Q₁＝∫f(P₂)dt

The heating energy is the heating energy of the contact surface of the adjacent battery;

step 2-3, drawing a temperature-time curve of the side face of the adjacent battery, which is in contact with the air; finding the battery surface temperature-time curve corresponding to the closest heating test, and estimating the heating power P of the smoke to the adjacent battery₃And calculating the heating energy Q based on the calculated values₂：

Q₂＝∫f(P₃)dt

Said heating energy Q₂The heating energy of the contact surface of the adjacent battery and the air;

step 2-4, calculating the energy Q released after the battery overcharging thermal runaway is triggered:

where n is the number of cells in a battery module or battery box in which the cells are grouped.

4. The method for judging the thermal runaway chain reaction of the energy storage battery pack according to claim 3, wherein the step 3 is specifically as follows:

when E is larger than or equal to Q, the battery does not generate thermal runaway chain reaction under the overcharge power;

when E < Q, thermal runaway chain reaction of the battery can occur under the overcharge power.

5. An energy storage battery pack thermal runaway chain reaction judgment system for realizing the method of any one of claims 1 to 4, which is characterized by comprising the following steps:

the battery overcharge energy calculation module is used for calculating overcharge energy when the battery is out of control due to overcharge;

the battery overcharge thermal runaway release energy calculation module is used for calculating the release energy of the battery after thermal runaway;

and the judging module is used for judging whether the thermal runaway chain reaction occurs in the battery according to the overcharged energy and the released energy.

6. A test device for carrying out the method of any one of claims 1 to 4, comprising:

the testing box is internally provided with 3 batteries which comprise overcharged batteries and adjacent batteries arranged on two sides of the overcharged batteries; the top, two sides and the front-back spacing of the 3 batteries and the inner side of the box body of the test box are consistent with the distance between the battery in the battery module and the box body;

a temperature measuring device including a first temperature sensor disposed between the battery and the battery, and a second temperature sensor of a side of the battery that is in contact with air;

the thermal resistance layer is arranged on the outer side surfaces of the two outermost batteries;

the upper computer is connected with the temperature measuring device and internally provided with the thermal runaway chain reaction judgment system of the energy storage battery pack according to claim 5.

7. The testing apparatus according to claim 6, wherein a third temperature sensor is further provided above the safety valve of the battery for recording the open flame temperature of the combustion gas-liquid mixture ejected during thermal runaway.

8. The testing device according to claim 6 or 7, wherein the thickness of the first temperature sensor and the second temperature sensor is 1 to 10 mm.

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