Battery pack with temperature early warning function and energy storage system

Abstract

The embodiment of the utility model provides a battery pack with a temperature early warning function and an energy storage system comprising the battery pack, and relates to the technical field of energy storage. The battery pack comprises a shell, a plurality of battery cells and a fire extinguishing agent, wherein an accommodating space is formed in the shell; the plurality of battery cells are arranged in the accommodating space; the plurality of battery cells comprise a first battery cell and a second battery cell, a fire extinguishing agent is arranged between the first battery cell and the second battery cell, and the fire extinguishing agent is used for absorbing heat at a preset temperature and decomposing to generate water and gas. The battery pack is provided with the fire extinguishing agent which is heated to decompose to generate water and gas, so that the effects of warning and reducing the explosion risk of the battery pack are achieved before or after the thermal runaway of the battery pack.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage, and in particular to a battery pack and an energy storage system with a temperature warning function. Background Art

[0002] As batteries (eg, lithium-ion batteries) gain more market share in the energy storage market and power equipment (eg, electric vehicles), users have increasingly higher requirements for battery safety.

[0003] Under conditions of overcharge, short circuit, overheating, etc., the battery temperature may increase cumulatively, which may put the battery at risk of thermal runaway. Thermal runaway of the battery will not only damage the battery itself, but may also cause safety problems such as fire and explosion, causing significant losses to users.

[0004] In related technologies, after a battery experiences thermal runaway, personnel are relatively passive in learning about the situation and are unable to respond quickly, which puts the battery at risk of continued combustion or even explosion. Utility Model Content

[0005] The present application provides a battery pack with a temperature warning function, and an energy storage system including the above-mentioned battery pack. The battery pack is provided with a fire extinguishing agent that decomposes under heat to produce water and gas, which plays a role in warning and reducing the risk of explosion of the battery pack before or after thermal runaway.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] In a first aspect of the present application, a battery pack is provided, which includes a shell, multiple battery cells and a fire extinguishing agent, wherein a storage space is formed inside the shell; the multiple battery cells are arranged in the storage space; the multiple battery cells include a first battery cell and a second battery cell, and a fire extinguishing agent is arranged between the first battery cell and the second battery cell, and the fire extinguishing agent is used to absorb heat and decompose at a preset temperature to produce water and gas.

[0008] The fire extinguishing agent is arranged between the first battery cell and the second battery cell so that the fire extinguishing agent can sense the temperature change of the battery cell more quickly. When the temperature of any one of the first battery cell and the second battery cell rises, the temperature can be quickly transferred to the fire extinguishing agent to heat the fire extinguishing agent. When the temperature of the battery pack rises, the fire extinguishing agent is at a preset temperature, and the fire extinguishing agent absorbs heat and decomposes to produce water (e.g., water vapor, etc.) and gas (e.g., easily identifiable gas). The process of pyrolysis of the fire extinguishing agent can absorb the heat of the first battery cell and the second battery cell, reducing the possibility of the temperature of the first battery cell and the second battery cell continuing to rise, and also lowering the temperature of the battery pack, reducing the possibility of heat spread.

[0009] After the gas produced by the pyrolysis of the fire extinguishing agent is detected, it can serve as a warning. For example, a detection device such as a sensor is set up to identify and detect the gas produced by the pyrolysis of the fire extinguishing agent. When the detection device detects the presence of the gas (there is no such gas in the air) or detects an increase in the concentration of the gas (the air originally has such gas), it will transmit a signal (for example, transmit a signal to the battery management system) to issue a warning. If the preset temperature is lower than the thermal runaway temperature of the battery pack, the gas produced by the pyrolysis of the fire extinguishing agent can remind relevant personnel that the battery pack is at risk of thermal runaway, so that relevant personnel can quickly respond to the thermal runaway of the battery pack. If the preset temperature is greater than the thermal runaway temperature of the battery pack, the gas produced by the pyrolysis of the fire extinguishing agent can remind relevant personnel to quickly extinguish the fire and reduce losses. In addition, the water vapor produced by the pyrolysis of the fire extinguishing agent can dilute the combustible gas or combustion-supporting gas (for example, oxygen) inside the battery pack, reducing the risk of explosion after the battery pack thermal runaway. When the battery pack catches fire, the water vapor released by the pyrolysis of the fire extinguishing agent can cool down and extinguish the fire, reducing the risk of continued combustion or even explosion of the battery pack.

[0010] In addition, the fire extinguishing agent is disposed between the first battery cell and the second battery cell, and there is no need to make significant changes to the structure of the battery cell, thereby reducing the manufacturing cost of the battery pack.

[0011] In an optional embodiment, the battery pack further includes a hot-melt film, which is wrapped around the fire extinguishing agent, and an outer film surface of the hot-melt film is in contact with outer walls of the first battery cell and the second battery cell, and the hot-melt film is used to melt at a preset temperature.

[0012] Wrapping the fire extinguishing agent with a hot melt film reduces the possibility of the fire extinguishing agent spreading or spilling, and facilitates the placement of the fire extinguishing agent between the first battery cell and the second battery cell. The two sides of the hot melt film are in contact with the first battery cell and the second battery cell respectively, and the heat of the first battery cell and the second battery cell can be transferred to the hot melt film, and then transferred to the fire extinguishing agent through the hot melt film. When the temperature of the first battery cell and the second battery cell rises and the hot melt film is at a preset temperature, the hot melt film melts, and the melted hot melt film exposes the fire extinguishing agent inside to the outside, so that the water and gas generated by the pyrolysis of the fire extinguishing agent can be released to the outside of the hot melt film.

[0013] In an optional embodiment, the fire extinguishing agent is a sheet fire extinguishing agent, the hot melt film includes two membranes, the sheet fire extinguishing agent is encapsulated between the two membranes, the edges of the two membranes are sealed and connected, and the surfaces of the two membranes facing away from the sheet fire extinguishing agent are in contact with the outer walls of the first battery cell and the second battery cell respectively.

[0014] The fire extinguishing agent is encapsulated between two diaphragms, and the edges of the two diaphragms are connected, which reduces the possibility of the fire extinguishing agent leaking from the edges of the two diaphragms, making the encapsulation effect of the fire extinguishing agent better. When the temperature of the first battery cell and the second battery cell rises, the diaphragm melts at a preset temperature and exposes the fire extinguishing agent outside the diaphragm. The fire extinguishing agent pyrolyzes at a preset temperature to produce water and gas, which serves as a warning and reduces the risk of battery pack explosion before or after thermal runaway.

[0015] In an optional embodiment, the outer wall of the first battery cell includes a square wall surface for contacting one of the diaphragms, both diaphragms are square-shaped, and the orthographic projection of the diaphragm in contact with the square wall surface on the square wall surface is located within the outer edge of the square wall surface.

[0016] By adopting the packaging scheme of the present application, the fire extinguishing agent and the hot-melt film form a fire extinguishing gasket, which is installed between the first battery cell and the second battery cell, and the shapes of the fire extinguishing agent and the hot-melt film are adapted to the shapes of the outer wall surfaces of the battery cells. After the hot-melt film and the fire extinguishing agent are placed, the orthographic projection of the diaphragm on the square wall surface is located on the inner side of the outer edge of the square wall surface, that is, the hot-melt film is located in the gap between the first battery cell and the second battery cell, and the edge of the diaphragm will not extend beyond the first battery cell, thereby reducing the influence of the diaphragm on the installation of the battery cells.

[0017] In an optional embodiment, two first poles are arranged on the top surface of the first battery cell, and two second poles are arranged on the top surface of the second battery cell. The distribution direction of the two first poles and the distribution direction of the two second poles are parallel to the first direction, and the first battery cell and the second battery cell are arranged along the first direction, or the first battery cell and the second battery cell are arranged along the second direction, and the second direction is perpendicular to the first direction.

[0018] The first battery cell and the second battery cell can be arranged along the first direction, and the first battery cell and the second battery cell can also be arranged along the second direction. The fire extinguishing agent is sandwiched between the first battery cell and the second battery cell. The heat of the first battery cell and the second battery cell is transferred to the fire extinguishing agent, so that the fire extinguishing agent absorbs heat and decomposes at a preset temperature to produce water and gas.

[0019] In an optional implementation, the size of the fire extinguishing agent in the distribution direction of the first battery core and the second battery core is 1 mm to 5 mm.

[0020] The size of the fire extinguishing agent in the distribution direction of the first battery cell and the second battery cell is smaller, so that the thickness of the fire extinguishing agent is thinner. In this way, the distance between the first battery cell and the second battery cell can be narrower, and more battery cells can be accommodated in the shell, which is beneficial to the installation of the battery cells in the shell and reduces the impact of the fire extinguishing agent on the energy density of the battery pack.

[0021] In an optional implementation, a fire extinguishing agent is coated on an outer wall of the first battery cell facing the second battery cell or on an outer wall of the second battery cell facing the first battery cell.

[0022] The fire extinguishing agent can be coated on the first battery cell and the second battery cell to form a fire extinguishing agent coating, so that the fire extinguishing agent can sense the temperature change of the battery cell more quickly. When the temperature of any one of the first battery cell and the second battery cell rises, the temperature can be quickly transferred to the fire extinguishing agent, so that the fire extinguishing agent is at a preset temperature. The fire extinguishing agent absorbs heat and decomposes to produce water and gas. The process of pyrolysis of the fire extinguishing agent can absorb the heat of the first battery cell and the second battery cell, reducing the possibility of further increase in the temperature of the first battery cell and the second battery cell. The gas produced by the pyrolysis of the fire extinguishing agent can be used as a signal gas and serve as a warning. When the battery cell catches fire, the water produced by the pyrolysis of the fire extinguishing agent can effectively extinguish the fire and reduce the risk of continued combustion or even explosion of the battery pack. In addition, the coating method does not require a major change to the structure of the battery cell, which reduces the manufacturing cost of the battery cell and avoids the energy density loss caused by the space occupied by the battery pack.

[0023] In an optional implementation, the outer wall of the side surface of the first battery cell and the outer wall of the side surface of the second battery cell are both coated with a fire extinguishing agent.

[0024] The fire extinguishing agent is coated on the periphery of the first battery cell and the periphery of the second battery cell, so that the coating area of ​​the fire extinguishing agent on the first battery cell and the second battery cell is larger (more fire extinguishing agent). The fire extinguishing agent forms a large-area coating, which can better play a warning, cooling and fire extinguishing role during thermal decomposition.

[0025] In an optional implementation, the inner wall surface of the shell is coated with a fire extinguishing agent, or the outer wall surface of the shell is coated with a fire extinguishing agent.

[0026] A fire extinguishing agent may also be applied to the inner wall surface and / or the outer wall surface of the shell to form a fire extinguishing agent coating on the shell. When the heat of the battery cell increases, the heat of the battery cell will be transferred to the shell. The increased temperature of the shell will heat the fire extinguishing agent, causing the fire extinguishing agent to pyrolyze. The pyrolysis process of the fire extinguishing agent absorbs heat and can cool the shell. When the battery pack catches fire, the water produced by the pyrolysis of the fire extinguishing agent falls on the shell and cools the shell. In addition, the pyrolyzed water can also extinguish the burning battery pack.

[0027] In an optional embodiment, the battery cell is electrically connected to a wire, the inner wall surface of the shell is provided with a groove, at least part of the wire is located in the groove, and the inner wall surface of the groove is coated with a fire extinguishing agent.

[0028] Fire extinguishing agent is applied on the wall of the groove for wiring (for example, wiring trough) on the shell, so that more areas of the shell are coated with fire extinguishing agent. The large area coating formed by the fire extinguishing agent can better play the role of warning, cooling and fire extinguishing during pyrolysis.

[0029] In an optional implementation, the preset temperature is 70°C to 200°C.

[0030] The thermal runaway temperature of a battery pack is usually high. The preset temperature is set at 70℃~200℃, that is, the preset temperature is lower than the thermal runaway temperature of the battery pack. The fire extinguishing agent absorbs the heat of the battery pack during the pyrolysis process, reducing the possibility of the battery pack continuing to heat up and thermal runaway. After the gas produced by the pyrolysis of the fire extinguishing agent is detected, it can serve as a warning to remind relevant personnel that the battery pack is at risk of thermal runaway, so that relevant personnel can take preventive measures before the battery pack thermal runaway occurs, thereby reducing losses.

[0031] In an optional embodiment, the fire extinguishing agent includes NH 4 M x PO 4 ·nH 2 O(n≥1).

[0032] NH 4 M x PO 4 ·nH 2 O can be thermally decomposed to produce ammonia (NH 3 ) and water, of which ammonia is the signal gas. When the detection device detects ammonia, it can alarm to indicate that the battery pack is at risk of thermal runaway. In addition, ammonia and water vapor can dilute the concentration of combustion-supporting gas (oxygen) and combustible gas in the air, and can also dilute the concentration of electrolyte vapor cloud after thermal runaway of the battery pack, reducing the risk of heat spread and explosion after thermal runaway of the battery pack. 4 M x PO 4 ·nH 2 O is ground into ultrafine powder and mixed with additives such as binders to make a fire extinguishing coating, which can be applied to the shell and battery core; NH 4 M x PO 4 ·nH 2 O powder is pressed into tablets and coated with hot-melt film on the outside, which can be made into fire extinguishing gaskets and installed between battery cells.

[0033] In an optional embodiment, the fire extinguishing agent includes NH 4 MgPO 4 6H 2 O.

[0034] NH 4 MgPO 4 6H 2 O (magnesium ammonium phosphate hexahydrate), commonly known as struvite, can undergo pyrolysis at around 85°C. NH 4 MgPO 4 6H 2 O, can undergo thermal decomposition at 97°C, NH 4MgPO 4 6H 2 O can be pyrolyzed to produce a large amount of NH 3 , H 2 O and PO groups absorb a lot of heat at the same time, reducing the heat of the battery pack and the risk of battery pack explosion. 4 MgPO 4 6H 2 The thermal decomposition product of O is magnesium pyrophosphate (Mg 2 P 2 O 7 ) has the characteristics of density, heat resistance and insulation. When attached to the surface of combustible materials (for example, the surface of the battery cell or the surface of the shell), it can block oxygen and reduce the risk of fire. It also plays a role in moisture and corrosion prevention.

[0035] In a second aspect of the present application, an energy storage system is provided, which includes a sensor, a battery management system and the above-mentioned battery pack, wherein the sensor is used to detect gas, and the sensor is electrically connected to the battery management system.

[0036] When the temperature of the battery pack rises, the fire extinguishing agent is at a preset temperature, and the fire extinguishing agent absorbs heat and decomposes to produce water and gas. The sensor is used to identify and detect the gas produced by the thermal decomposition of the fire extinguishing agent. When the sensor detects the presence of the gas, or detects an increase in the concentration of the gas, it will transmit a signal to the battery management system. The battery management system issues a warning to remind relevant personnel that the battery pack is at risk of thermal runaway, so that relevant personnel can quickly respond to the thermal runaway of the battery pack and reduce losses. In addition, the energy storage system provided in this application includes the above-mentioned battery pack, so the energy storage system provided in this application and the battery pack of the above-mentioned technical solution can solve the same technical problems and have the same technical effects, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of an energy storage system provided in an embodiment of the present application;

[0038] Figure 2 A schematic diagram of the structure of a battery pack provided in an embodiment of the present application;

[0039] Figure 3 NH provided in the embodiment of the present application 4 MgPO 4 6H 2 Differential scanning calorimetry curve of O;

[0040] Figure 4 A schematic diagram of the distribution of the first battery cell and the second battery cell provided in an embodiment of the present application;

[0041] Figure 5Another schematic diagram of the distribution of the first battery cell and the second battery cell provided in an embodiment of the present application;

[0042] Figure 6 A schematic diagram of the structure of the hot melt film and the fire extinguishing agent provided in the embodiment of the present application;

[0043] Figure 7 A schematic diagram of the packaging structure of the hot melt film provided in the embodiment of the present application;

[0044] Figure 8 A schematic diagram of the structure of another battery pack provided in an embodiment of the present application.

[0045] Reference numerals:

[0046] 100-energy storage system; 110-battery pack; 1-shell; 11-tray; 12-protective cover; 2-battery cell; 21-first battery cell; 211-first pole; 212-square wall; 22-second battery cell; 221-second pole; 3-fire extinguishing agent; 4-hot-melt film; 41-diaphragm; 411-edge portion; 120-sensor; 130-battery management system; 140-protective structure. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0048] In this application, the terms "first", "second", etc. are used only for descriptive purposes to distinguish one element from another, and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. Moreover, in this application, unless otherwise expressly specified and limited, the meaning of "plurality" is two or more.

[0049] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, 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 it can be indirectly connected through an intermediate medium, or it can be internal communication between two components. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to specific circumstances. In addition, when describing pipelines or channels, the "connected" and "connected" used in this application have the meaning of conduction. The specific meaning needs to be understood in conjunction with the context.

[0050] In addition, in this application, the words "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0051] In the drawings of the embodiments of the present application, solid structures such as components and assemblies are represented by guide lines; hollow structures such as openings, holes, spaces, and cavities are represented by guide lines with arrows.

[0052] An energy storage system 100 provided in an embodiment of the present application is referred to Figure 1 , Figure 1 The structure diagram of the energy storage system 100 is shown as an example, and the exemplary energy storage system 100 includes a battery pack 110, a sensor 120, and a battery management system 130. A plurality of battery packs 110 may be provided, and the plurality of battery packs 110 are all provided in an external protective structure 140 (e.g., a box body of an energy storage container, a cabinet body of an energy storage cabinet, etc.) of the energy storage system 100.

[0053] Sensor 120 may be a gas monitoring sensor, see Figure 1 , the sensor 120 of the example is disposed inside the battery pack 110, and in other examples, the sensor 120 may also be disposed outside the battery pack 110. The sensor 120 is used to detect a certain gas (referred to as a signal gas) present inside or around the battery pack 110. For example, when the signal gas content in the air is very small or the air does not contain the signal gas, the sensor 120 may be a sensor for detecting whether the signal gas is present; when the air contains the signal gas, the sensor 120 may be a sensor for detecting the concentration of the signal gas. The sensor 120 may be a semiconductor gas sensor, an electrochemical gas sensor, an optical waveguide gas detector, and the like, and the present application does not impose any specific restrictions thereon.

[0054] The battery management system 130 (BMS) may be disposed inside the battery pack 110, outside the battery pack 110, or outside the external protection structure 140. Figure 1 The example in which the battery management system 130 is arranged outside the battery pack 110 and inside the protective structure 140 is shown. The sensor 120 is electrically connected to the battery management system 130. When the sensor 120 detects the signal gas, it transmits a signal to the battery management system 130. The battery management system 130 sends a prompt signal to the relevant personnel through at least one of an alarm, mobile phone software, and a control panel to warn.

[0055] The present application also provides a battery pack 110, Figure 2 The structure of the battery pack 110 is shown as an example. Figure 2 The battery pack 110 includes a housing 1 and a plurality of battery cells 2 (for example, lithium battery cells). A storage space (not shown in the drawings) is formed inside the housing 1, and the plurality of battery cells 2 are arranged in the storage space. For example, the housing 1 may include a tray 11 and a protective cover 12, the plurality of battery cells 2 are arranged on the tray 11, the protective cover 12 is arranged outside the battery cells 2, and the protective cover 12 and the tray 11 together form a storage space for accommodating the plurality of battery cells 2.

[0056] When the battery pack 110 is overcharged, short-circuited, or overheated, the temperature of the battery cells 2 will increase cumulatively, causing the battery pack 110 to have a risk of thermal runaway. Thermal runaway of the battery pack 110 will not only damage the battery pack 110 itself, but may also cause safety issues such as fire and explosion, causing significant losses to users.

[0057] In order to serve as a warning and reduce the risk of explosion of the battery pack 110 before or after thermal runaway, the battery pack 110 of the present application also includes a fire extinguishing agent 3. The battery pack 110 has a preset temperature, and the fire extinguishing agent 3 is used to absorb heat and decompose at the preset temperature to produce water (for example, water vapor, etc.) and gas.

[0058] When the fire extinguishing agent 3 is at the preset temperature, it does not mean that the temperature of all areas of the battery pack 110 is the preset temperature. The fire extinguishing agent 3 pyrolyzes at the preset temperature, which means that the pyrolysis temperature of the fire extinguishing agent 3 is equal to or less than the preset temperature. After the fire extinguishing agent 3 starts to pyrolyze, if the temperature of the environment in which the fire extinguishing agent 3 is located continues to rise, the fire extinguishing agent 3 will continue to absorb heat, and the fire extinguishing agent 3 can continue to pyrolyze until the pyrolysis is finally completed.

[0059] In one embodiment, the preset temperature may be lower than the thermal runaway temperature of the battery pack 110 (or the thermal runaway temperature of the battery cell 2), that is, the temperature at which the fire extinguishing agent 3 starts to pyrolyze is lower than the thermal runaway temperature of the battery pack 110. Before the battery pack 110 goes into thermal runaway (for example, when it is about to go into thermal runaway), the fire extinguishing agent 3 starts to pyrolyze, and the fire extinguishing agent 3 absorbs the heat of the battery pack 110 during the pyrolysis process, thereby reducing the possibility of the battery pack 110 continuing to heat up and going into thermal runaway.

[0060] The gas generated by the thermal decomposition of the fire extinguishing agent 3 can be used as a signal gas, that is, the gas generated by the thermal decomposition of the fire extinguishing agent 3 can be detected or identified by the sensor 120 (or other gas detection devices). Before the battery pack 110 thermally runs away, after the sensor 120 detects the signal gas, it will transmit a signal to the battery management system 130, and the battery management system 130 will issue a warning to the relevant personnel, reminding the relevant personnel that the battery pack 110 is at risk of thermal runaway, so that the relevant personnel can quickly take preventive measures to deal with the thermal runaway of the battery pack 110 before the battery pack 110 thermally runs away.

[0061] In an embodiment where the preset temperature is less than the thermal runaway temperature of the battery pack 110, the preset temperature may be 70°C to 200°C, for example, the preset temperature may be 70°C, 100°C, 180°C, 200°C, etc. The temperature at which the fire extinguishing agent 3 starts to pyrolyze may be 70°C to 200°C, for example, the temperature at which the fire extinguishing agent 3 starts to pyrolyze may be 70°C, 100°C, 180°C, 200°C, etc. Further, the preset temperature may be 80°C to 150°C, for example, the preset temperature may be 80°C, 85°C, 97°C, 150°C, etc. The temperature at which the fire extinguishing agent 3 starts to pyrolyze may be 80°C to 150°C, for example, the temperature at which the fire extinguishing agent 3 starts to pyrolyze may be 80°C, 85°C, 97°C, 150°C, etc.

[0062] In another embodiment, the preset temperature may be greater than the thermal runaway temperature of the battery pack 110, and the temperature at which the fire extinguishing agent 3 begins to pyrolyze may also be greater than the thermal runaway temperature of the battery pack 110. That is, the fire extinguishing agent 3 begins to pyrolyze after the battery pack 110 is in thermal runaway, and the fire extinguishing agent 3 absorbs the heat of the battery pack 110 during the pyrolysis process, reducing the possibility of further increase in the heat of the battery pack 110. After the sensor 120 detects the signal gas, it will transmit a signal to the battery management system 130, and the battery management system 130 will issue a warning to relevant personnel, reminding them that the battery pack 110 has thermal runaway, so that relevant personnel can quickly extinguish the fire in the battery pack 110 and reduce losses.

[0063] In addition, regardless of the relationship between the preset temperature and the thermal runaway temperature of the battery pack 110, the water vapor generated by the pyrolysis of the fire extinguishing agent 3 can dilute the combustible gas or combustion-supporting gas inside the battery pack 110, and can also reduce the concentration of the electrolyte vapor cloud of the battery pack 110 after thermal runaway, thereby reducing the possibility of explosion after thermal runaway of the battery pack 110. When the battery pack 110 catches fire, the water generated by the pyrolysis of the fire extinguishing agent 3 can effectively extinguish the fire, reducing the risk of continued combustion or even explosion of the battery pack 110.

[0064] In summary, the battery pack 110 of the present application includes the fire extinguishing agent 3, which can play a role in warning and reducing the risk of explosion of the battery pack 110 before or after the thermal runaway of the battery pack 110.

[0065] The fire extinguishing agent 3 may be any suitable fire extinguishing agent. In one embodiment, the fire extinguishing agent 3 includes NH 4 M x PO 4 ·nH 2 O(n≥1). Wherein, M is a metal element, for example, M can be one of the elements such as Ca, Mg, Zn, Cu, etc.; x is the number of M atoms, x≥1, for example, x is 1 or 2, etc.; n is H 2The number of O, for example, n is 1, 2, 3, 4 or 5. NH 4 M x PO 4 ·nH 2 O can be pyrolyzed to produce ammonia (NH 3 ) and water, ammonia can be used as a signal gas. When the sensor 120 detects ammonia, an alarm can be issued to indicate that the battery pack 110 is at risk of thermal runaway. In addition, ammonia and water vapor can dilute the concentration of combustion-supporting and combustible gases in the air, and can also dilute the concentration of electrolyte vapor cloud after thermal runaway of the battery pack 110, thereby reducing the risk of explosion after thermal runaway of the battery pack 110.

[0066] For example, the fire extinguishing agent 3 may include NH 4 MgPO 4 6H 2 O (magnesium ammonium phosphate hexahydrate), commonly known as struvite, Figure 3 NH is shown as an example 4 MgPO 4 6H 2 Differential Scanning Calorim (DSC) curve of O, refer to Figure 3 The DSC curves shown are for NH 4 MgPO 4 6H 2 O can undergo pyrolysis at around 85 °C. In some other examples, NH 4 MgPO 4 6H 2 O, can undergo thermal decomposition at 97°C. NH 4 MgPO 4 6H 2 O can be pyrolyzed to produce a large amount of NH at a preset temperature (greater than or equal to the temperature at which pyrolysis begins). 3 , H 2 O and PO groups have a higher enthalpy change endothermicity, while NH 4 MgPO 4 6H 2 O absorbs a large amount of heat during the thermal decomposition process, which reduces the temperature of the battery pack 110 and reduces the risk of further temperature out of control of the battery pack 110.

[0067] In addition, NH 4 MgPO 4 6H 2 The thermal decomposition product of O is magnesium pyrophosphate (Mg 2 P 2 O 7) is a dense heat-resistant ceramic with a melting point of up to 1383°C. It has the characteristics of density, heat resistance and insulation. It has no corrosive effect on equipment. It can be attached to the surface of combustible materials (for example, the surface of the battery cell 2 or the surface of the shell 1) to block oxygen and reduce the fire risk of the battery pack 110. It also plays a role in moisture-proof and corrosion-resistant.

[0068] In other examples, the fire extinguishing agent 3 may also include baking soda, ammonium carbonate, or ammonium phosphate, etc.

[0069] The fire extinguishing agent 3 of the present application can be set at any suitable position of the battery pack 110. In one embodiment, refer to Figure 4 and Figure 5 The plurality of battery cells 2 include a first battery cell 21 and a second battery cell 22, and the fire extinguishing agent 3 is disposed between the first battery cell 21 and the second battery cell 22. Figure 4 An exemplary arrangement of the first battery cell 21 and the second battery cell 22 is shown. Figure 5 Another arrangement of the first battery cells 21 and the second battery cells 22 is shown as an example.

[0070] Reference Figure 4 and Figure 5 , one of the two back-to-back walls of the first battery cell 21 in the third direction is provided with two first poles 211, and one of the two back-to-back walls of the second battery cell 22 in the third direction is provided with two second poles 221, and the two first poles 211 and the two second poles 221 are all facing the same side of the first battery cell 21 in the third direction. For example, the third direction is the vertical direction after the battery cell 2 is installed, and the two back-to-back surfaces of the first battery cell 21 in the third direction are the top surface and the bottom surface of the first battery cell 21, respectively. The top surface of the first battery cell 21 facing upward after installation is provided with two first poles 211, and similarly, the top surface of the second battery cell 22 facing upward after installation is provided with two second poles 221. The distribution directions of the two first poles 211 and the distribution directions of the two second poles 221 are both parallel to the first direction, and the third direction is perpendicular to the first direction. For example, after the battery cell 2 is installed, the first direction is parallel to the horizontal plane.

[0071] In one example, referring to Figure 4 , the fire extinguishing agent 3 can be sandwiched between the first battery cell 21 and the second battery cell 22 arranged along the first direction. Figure 5 The fire extinguishing agent 3 is sandwiched between the first battery cell 21 and the second battery cell 22 arranged along the second direction. The first direction, the second direction and the third direction are perpendicular to each other, or in other words, the first direction, the second direction and the third direction are three mutually perpendicular directions.

[0072] Reference Figure 4 and Figure 5In order to facilitate the placement of the fire extinguishing agent 3, the fire extinguishing agent 3 can be compacted into a sheet, that is, the fire extinguishing agent 3 is a sheet-shaped fire extinguishing agent, and the size of the fire extinguishing agent 3 (sheet-shaped fire extinguishing agent) in the distribution direction of the first battery cell 21 and the second battery cell 22 can be 1mm-5mm, that is, the thickness of the fire extinguishing agent 3 can be 1mm-5mm. For example, the size of the fire extinguishing agent 3 in the distribution direction of the first battery cell 21 and the second battery cell 22 can be 1mm, 2mm, 3mm, 4mm, 5mm, etc. The fire extinguishing agent 3 includes NH 4 MgPO 4 6H 2 In the example of O, NH 4 MgPO 4 6H 2 O is ground into ultrafine powder, mixed with additives such as a binder, and pressed into a thin sheet with a thickness of 1 mm to 5 mm to form the above-mentioned flaky fire extinguishing agent.

[0073] Through the above-mentioned design method, the size of the fire extinguishing agent 3 in the distribution direction of the first battery cell 21 and the second battery cell 22 is set to be smaller, so that the thickness of the fire extinguishing agent 3 is thinner, and the distance between the first battery cell 21 and the second battery cell 22 can be narrower. More battery cells 2 can be accommodated in the shell 1, which is beneficial to the installation of the battery cells 2 in the shell 1, and also reduces the impact of the fire extinguishing agent 3 on the energy density of the battery pack 110.

[0074] In one example, the battery cell 2 may be in a square shape, and the fire extinguishing agent 3 may be pressed into a square sheet shape in order to fit the battery cell 2. In other examples, the fire extinguishing agent 3 may also be pressed into a disc shape.

[0075] To reduce the possibility of scattering or splashing of the fire extinguishing agent 3, refer to Figure 4 or Figure 5 The battery pack 110 may further include a hot melt film 4, which is wrapped around the fire extinguishing agent 3, so as to facilitate the placement of the fire extinguishing agent 3 between the first battery cell 21 and the second battery cell 22. The outer wall of the first battery cell 21 and the outer wall of the second battery cell 22 are both in contact with the hot melt film 4, that is, the outer film surface on one side of the hot melt film 4 is in contact with the outer wall surface of the first battery cell 21, and the outer film surface on the other side of the hot melt film 4 is in contact with the outer wall surface of the second battery cell 22. The heat of the first battery cell 21 and the second battery cell 22 can be transferred to the hot melt film 4, and the hot melt film 4 is used to melt at a preset temperature.

[0076] When the hot melt film 4 is at a preset temperature, it does not mean that the temperature of all areas of the battery pack 110 is at the preset temperature. The hot melt film 4 melts at the preset temperature, which means that the melting point of the hot melt film 4 is equal to or lower than the preset temperature. After the hot melt film 4 begins to melt, if the ambient temperature of the hot melt film 4 continues to rise, the hot melt film 4 continues to absorb heat, and the hot melt film 4 can also continue to melt until the melting is completed. The preset temperature is a temperature that can cause the hot melt film 4 to melt and the fire extinguishing agent 3 to pyrolyze.

[0077] In one embodiment, the preset temperature may be lower than the thermal runaway temperature of the battery pack 110 (or the thermal runaway temperature of the battery cell 2), that is, the melting point of the hot melt film 4 is lower than the thermal runaway temperature of the battery pack 110. Before the battery pack 110 goes into thermal runaway (for example, when it is about to go into thermal runaway), the hot melt film 4 begins to melt, and the melted hot melt film 4 exposes the fire extinguishing agent 3 inside to the outside, so that the water and gas generated by the pyrolysis of the fire extinguishing agent 3 can be released to the outside of the hot melt film 4.

[0078] In an embodiment where the preset temperature is less than the thermal runaway temperature of the battery pack 110, the preset temperature may be 70°C to 200°C, for example, the preset temperature may be 70°C, 80°C, 100°C, 120°C, 150°C, 200°C, etc. The melting point of the hot melt film 4 may be 70°C to 200°C, for example, the temperature at which the hot melt film 4 begins to pyrolyze may be 70°C, 80°C, 100°C, 120°C, 150°C, 200°C, etc.

[0079] In another embodiment, the preset temperature may be greater than the thermal runaway temperature of the battery pack 110, and the melting point of the hot melt film 4 is also greater than the thermal runaway temperature of the battery pack 110. That is, the hot melt film 4 begins to pyrolyze after the battery pack 110 is in thermal runaway, so that the water and gas generated by the pyrolysis of the fire extinguishing agent 3 can be released outside the hot melt film 4, thereby playing the role of warning, extinguishing fire and reducing the risk of explosion of the battery pack 110.

[0080] The temperature at which the fire extinguishing agent 3 starts to pyrolyze may be the same as or different from the melting point of the hot melt film 4. For example, the temperature at which the fire extinguishing agent 3 starts to pyrolyze may differ from the melting point of the hot melt film 4 by ±5°C, ±10°C, ±20°C, etc.

[0081] In one example, when the fire extinguishing agent 3 begins to pyrolyze and the hot melt film 4 has not yet melted, the fire extinguishing agent 3 can absorb heat in the hot melt film 4 to cool down the first battery cell 21 and the second battery cell 22. In another example, when the hot melt film 4 begins to melt and the fire extinguishing agent 3 has not yet begun to pyrolyze, the fire extinguishing agent 3 can be exposed outside the hot melt film and gradually pyrolyze at high temperature.

[0082] In one example, the heat insulation of the hot melt film 4 is poor. When the hot melt film 4 is at a preset temperature, the fire extinguishing agent 3 is also at a preset temperature. In another example, the heat insulation of the hot melt film 4 is good. The hot melt film 4 is at a preset temperature, and the fire extinguishing agent 3 is at a temperature lower than the preset temperature. When the hot melt film 4 melts, the fire extinguishing agent 3 is exposed to the outside and begins to pyrolyze at the preset temperature.

[0083] The hot melt film 4 can be any film structure that can be melted at a preset temperature, for example, Figure 4 or Figure 5The hot melt film 4 may include two diaphragms 41 (e.g., sheet-shaped plastic films), the fire extinguishing agent 3 is encapsulated (e.g., plastic-sealed) between the two diaphragms 41, and the film surfaces of the two diaphragms 41 facing away from the fire extinguishing agent 3 are in contact with the outer wall surfaces of the first battery cell 21 and the second battery cell 22 respectively. When the temperature of the first battery cell 21 and the second battery cell 22 gradually increases, the diaphragms 41 melt and expose the fire extinguishing agent 3 outside the diaphragms 41.

[0084] Figure 6 The extinguishing agent 3 is shown as an example in which the extinguishing agent 3 is located between two membranes 41. The granular shaded portion in the figure is the extinguishing agent 3. The edge portions 411 of the two membranes 41 are connected (for example, thermoplastic connection). Figure 7 The connection of the edge portions 411 of the two membranes 41 is shown as an example. The edge portions 411 of the two membranes 41 are arranged around the fire extinguishing agent 3, which reduces the possibility of the fire extinguishing agent 3 leaking from the edges of the two membranes 41, and makes the packaging effect of the fire extinguishing agent 3 better.

[0085] In order to adapt to the shape of the wall of the battery cell 2, return to reference Figure 4 or Figure 5 The outer wall of the first battery cell 21 includes a square wall surface 212 for contacting one of the diaphragms 41 (the "wall" in this application refers to a solid wall with thickness, and the "wall surface" in this application refers to the surface of the "wall"). The fire extinguishing agent 3 includes a square sheet-shaped fire extinguishing agent. Both diaphragms 41 are in the shape of square sheets. The orthographic projection of the diaphragm 41 in contact with the first battery cell 21 on the square wall surface 212 is located on the inner side of the outer edge of the square wall surface 212, that is, the hot melt film 4 is located in the gap between the first battery cell 21 and the second battery cell 22. The edge of the diaphragm 41 will not exceed the outer edge of the first battery cell 21, reducing the impact of the diaphragm 41 on the installation of the battery cell 2. In other examples, the diaphragm 41 can also be a disc.

[0086] In other examples, multiple battery cells 2 are arranged along the first direction, and among the multiple battery cells 2 arranged in the first direction, a fire extinguishing agent 3 is sandwiched between any two adjacent battery cells 2. In other examples, multiple battery cells 2 are arranged along the second direction, and among the multiple battery cells 2 arranged in the second direction, a fire extinguishing agent 3 is sandwiched between any two adjacent battery cells 2. In other examples, a fire extinguishing agent 3 is sandwiched between each battery cell 2 and another battery cell 2 on one side in the first direction and another battery cell 2 on one side in the second direction.

[0087] The fire extinguishing agent 3 is arranged between the first battery cell 21 and the second battery cell 22, and the structure of the battery cell 2 does not need to be changed to a large extent, thereby reducing the manufacturing cost of the battery cell 2. Figure 8 , Figure 8 Another structure of a battery pack 110 is shown as an example. The outer wall surface of at least one battery cell 2 may be coated with a fire extinguishing agent 3. Figure 8The granular shaded portion on the middle cell 2 represents a coating formed by the fire extinguishing agent 3. For example, the fire extinguishing agent 3 includes a fire extinguishing base material (e.g., NH 4 MgPO 4 6H 2 O, baking soda, ammonium carbonate, ammonium phosphate, etc.), an appropriate amount of lubricant (for example, magnesium stearate, mica powder, talcum powder, etc.), a small amount of moisture-proof agent (for example, silica gel), etc., the above materials are mixed and ground together to form fine particles, mixed with additives such as binders to form a fire extinguishing agent coating, and applied to the surface of the outer shell of the battery cell 2.

[0088] In one example, referring to Figure 8 The outer wall surface of each battery cell 2 in the shell 1 is coated with the fire extinguishing agent 3, and the outer wall surface of each battery cell 2 coated with the fire extinguishing agent 3 is arranged around its own pole, that is, the two back-to-back walls of each battery cell 2 in the second direction and the two back-to-back walls in the first direction are coated with the fire extinguishing agent 3.

[0089] In another example, the outer wall surface of one or some of the battery cells 2 in the housing 1 is coated with a fire extinguishing agent 3. For example, the outer wall (peripheral wall) on the side of the first battery cell 21 and the outer wall (peripheral wall) on the side of the second battery cell 22 are both coated with a fire extinguishing agent. That is, the two back-to-back walls of the first battery cell 21 in the first direction and the two back-to-back walls in the second direction are both coated with a fire extinguishing agent 3; the two back-to-back walls of the second battery cell 22 in the first direction and the two back-to-back walls in the second direction are both coated with a fire extinguishing agent 3. In other examples, the top and bottom surfaces of the first battery cell 21 and the top and bottom surfaces of the second battery cell 22 can be coated with a fire extinguishing agent 3.

[0090] In another example, a portion of the wall surface of one or more of the battery cells 2 in the housing 1 is coated with the fire extinguishing agent 3. For example, only the outer wall of the first battery cell 21 facing the second battery cell 22 is coated with the fire extinguishing agent 3, or only the outer wall of the second battery cell 22 facing the first battery cell 21 is coated with the fire extinguishing agent 3. For another example, the outer wall of the first battery cell 21 facing the second battery cell 22 is coated with the fire extinguishing agent 3, and the outer wall of the second battery cell 22 facing the first battery cell 21 is also coated with the fire extinguishing agent 3.

[0091] The fire extinguishing agent 3 is coated on the outer wall of the battery cell 2, which means that the fire extinguishing agent 3 is coated on the outer surface of the corresponding wall, so that a fire extinguishing agent coating is formed on the outer wall surface of the battery cell 2. When the temperature of the battery cell 2 rises, the fire extinguishing agent 3 absorbs heat and decomposes to produce water and gas. The process of pyrolysis of the fire extinguishing agent 3 can absorb the heat of the battery cell 2, reducing the possibility of further increase in the temperature of the battery cell 2. The gas produced by the pyrolysis of the fire extinguishing agent 3 can be used as a signal gas and play a warning role. When the battery cell 2 catches fire, the water produced by the pyrolysis of the fire extinguishing agent 3 can effectively extinguish the open flame and reduce the risk of continuous combustion or even explosion of the battery pack 110. The pyrolysis products of the fire extinguishing agent 3 can be attached to the outer surface of the battery cell 2, which plays a role in blocking oxygen and reducing the risk of fire and explosion. In addition, by adopting the coating method, there is no need to make major changes to the structure of the battery cell 2, thereby reducing the production cost of the battery cell 2.

[0092] In another embodiment, referring to Figure 8 The wall surface of the housing 1 that forms the accommodating space is coated with the fire extinguishing agent 3 (the coating of the fire extinguishing agent 3 is not shown in the drawings), that is, the inner wall surface of the housing 1 is coated with the fire extinguishing agent 3.

[0093] In another embodiment, referring to Figure 8 The outer wall of the shell 1 is coated with a fire extinguishing agent 3, Figure 8 The granular shadow portion on the outer wall of the middle shell 1 represents the coating formed by the fire extinguishing agent 3 .

[0094] In another embodiment, the wall surface of the housing 1 that forms the accommodating space and the outer wall surface of the housing 1 are both coated with the fire extinguishing agent 3 .

[0095] The fire extinguishing agent 3 is applied on the shell 1 to form a coating. When the heat of the battery cell 2 increases, the heat of the battery cell 2 will be transferred to the shell 1. The increase in the temperature of the shell 1 will heat the fire extinguishing agent 3. The fire extinguishing agent 3 pyrolyzes to cool the shell 1, reducing the possibility of further temperature increase of the battery pack 110. When the battery pack 110 catches fire, the water produced by the pyrolysis of the fire extinguishing agent 3 falls on the shell 1 and cools the shell 1, which can also extinguish the fire of the battery pack 110. The pyrolysis products of the fire extinguishing agent 3 can be attached to the surface of the shell 1 or the surface of the battery cell 2, which can block oxygen and reduce the risk of fire and explosion. In addition, by adopting the coating method, there is no need to make major changes to the structure of the shell 1, thereby reducing the production cost of the battery pack 110.

[0096] In another embodiment, referring to Figure 2 The battery cell 2 is electrically connected to a wire (not shown in the drawings), and a groove (not shown in the drawings) is provided on the wall surface (inner wall surface) of the housing 1 that forms the accommodation space. For example, the groove can be provided on the inner wall surface of the protective cover 12. The groove can be a wiring groove, and at least part of the wire is located in the groove. The groove provides a placement space for the wire, and the inner wall surface of the groove is coated with a fire extinguishing agent 3.

[0097] The fire extinguishing agent 3 is coated on the wall of the groove for wiring on the housing 1, so that more areas of the housing 1 are provided with the fire extinguishing agent 3, and the large-area coating formed by the fire extinguishing agent 3 can better play the role of warning, cooling and extinguishing fire. In addition, when the battery pack 110 is about to thermally run away, the temperature of the wire is high, and the fire extinguishing agent 3 coated on the wall of the groove can also be pyrolyzed to produce water and gas under the heating of the wire temperature, cooling the wire and extinguishing the fire.

[0098] In addition, the position of the sensor 120 can be set as required. For example, in the example where the fire extinguishing agent 3 is arranged between the multiple battery cells 2, the sensor 120 is arranged inside the housing 1. When the fire extinguishing agent 3 is only applied to the inner wall surface of the housing 1, the sensor 120 can also be arranged inside the housing 1. In the example where the fire extinguishing agent 3 is applied to the outer wall surface of the housing 1, the sensor 120 can be arranged outside the housing 1 (for example, the sensor 120 is arranged inside and outside the housing 1), and the sensor 120 outside the housing 1 is used to detect the gas produced by the thermal decomposition of the fire extinguishing agent 3 on the outer wall surface of the housing 1.

[0099] In other embodiments, the battery pack 110 of the present application may also be installed on an electric vehicle.

[0100] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A battery pack with a temperature warning function, characterized in that: include: A housing, wherein a receiving space is formed inside the housing; A plurality of battery cells, wherein the plurality of battery cells are arranged in the accommodation space; The fire extinguishing agent is used for decomposing the fire extinguishing agent at a preset temperature to produce water and gas.

2. The battery pack according to claim 1, characterized in that: The battery pack further includes a hot-melt film, which is wrapped around the fire extinguishing agent. The outer film surface of the hot-melt film contacts the outer walls of the first battery cell and the second battery cell, and the hot-melt film is used to melt at the preset temperature.

3. The battery pack according to claim 2, characterized in that: The fire extinguishing agent is a sheet-like fire extinguishing agent, and the hot-melt film includes two membranes. The sheet-like fire extinguishing agent is encapsulated between the two membranes. The edges of the two membranes are sealed and connected, and the surfaces of the two membranes facing away from the sheet-like fire extinguishing agent are in contact with the outer walls of the first battery cell and the second battery cell respectively.

4. The battery pack according to claim 3, characterized in that: The outer wall of the first battery cell includes a square wall surface for contacting one of the diaphragms, both of the diaphragms are in the shape of square sheets, and the orthographic projection of the diaphragm in contact with the square wall surface on the square wall surface is located within the outer edge of the square wall surface.

5. The battery pack according to any one of claims 1 to 4, characterized in that: Two first poles are arranged on the top surface of the first battery cell, and two second poles are arranged on the top surface of the second battery cell, and the distribution direction of the two first poles and the distribution direction of the two second poles are both parallel to the first direction. The first battery cell and the second battery cell are arranged along the first direction, or the first battery cell and the second battery cell are arranged along a second direction, and the second direction is perpendicular to the first direction.

6. The battery pack according to any one of claims 1 to 4, characterized in that: The size of the fire extinguishing agent in the distribution direction of the first battery core and the second battery core is 1 mm to 5 mm.

7. The battery pack according to claim 1, characterized in that: The fire extinguishing agent is coated on an outer wall of the first battery core facing the second battery core or on an outer wall of the second battery core facing the first battery core.

8. The battery pack according to claim 7, characterized in that: The outer wall of the side surface of the first battery cell and the outer wall of the side surface of the second battery cell are both coated with the fire extinguishing agent.

9. The battery pack according to any one of claims 1 to 4, characterized in that: The fire extinguishing agent is coated on the inner wall surface of the shell, or the fire extinguishing agent is coated on the outer wall surface of the shell.

10. The battery pack according to any one of claims 1 to 4, characterized in that: The battery core is electrically connected with a wire, the inner wall surface of the shell is provided with a groove, at least part of the wire is located in the groove, and the inner wall surface of the groove is coated with the fire extinguishing agent.

11. The battery pack according to any one of claims 1 to 4, characterized in that: The preset temperature is 70°C to 200°C.

12. The battery pack according to any one of claims 1 to 4, characterized in that: The fire extinguishing agent includes NH4M x PO4·nH2O(n≥1).

13. The battery pack according to claim 12, characterized in that: The fire extinguishing agent includes NH4MgPO4·6H2O.

14. An energy storage system, characterized in that: The invention comprises a sensor, a battery management system and a battery pack according to any one of claims 1 to 13, wherein the sensor is used to detect the gas, and the sensor is electrically connected to the battery management system.

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