Battery pack and power battery pack

Abstract

The application relates to the battery technical field and discloses a battery pack and a power battery pack. The battery pack comprises a battery heat insulation unit, the battery heat insulation unit comprises a partition piece, the partition piece is provided with a partition plate, and the partition plate is fixedly connected with a battery monomer. The battery monomer comprises an electric core and a battery shell, the battery shell is provided with a first side wall opposite to the partition plate, a heat resistance groove is arranged at the connecting position between the first side wall and the bottom wall of the battery shell, the heat resistance groove is recessed towards the inside of the battery shell and is located below the electric core, the interval distance between the bottom of the pole piece of the electric core and the bottom wall of the battery shell is Hmm, the interval distance between the bottom of the pole piece of the electric core and the heat resistance groove is hmm, the thickness dimension of the partition plate is dmm, and 0.1 <= (Hmm-hmm) / dmm <= 5. When the partition piece conducts heat under the influence of the adjacent environment, the cavity in the heat resistance groove can hinder the heat conduction from the partition piece to the bottom end of the battery shell, so that the thermal runaway of the battery monomer can be prevented.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery pack and a power battery pack having the battery pack. Background Technology

[0002] The power battery pack contains at least one battery group, and each battery group consists of at least one battery cell. When a battery cell experiences thermal runaway due to overheating, damage, or contact between the positive and negative electrodes, a violent chemical reaction occurs inside the battery cell, generating a large amount of heat. This heat is conducted to adjacent battery cells within the power battery pack, causing the adjacent battery cells to be affected and experience thermal runaway, ultimately resulting in partial or complete burnout of the power battery pack.

[0003] In related technologies, in existing power battery packs, when the electrode plates of the battery cells are in a stacked configuration, in order to reduce the impact of the heat generated by the battery cells in thermal runaway on adjacent battery cells, a separator plate is installed between two adjacent battery cells along the thickness direction of the battery cells. The separator plate can reduce the heat conducted between two adjacent battery cells. Furthermore, since the surface area of ​​the battery cell in contact with the separator plate is large enough, the remaining heat conducted from the separator plate to the battery cell will be conducted and dissipated to the battery cell as a whole through the surface of the battery cell in contact with the separator plate, which can prevent the chain thermal runaway problem caused by the local temperature of the battery cell being too high.

[0004] However, when some heat is conducted to the bottom wall of the battery cell through the separator, the heat can easily cause the bottom of the battery cell to overheat and thermal runaway due to the small area of ​​the bottom wall of the battery cell, thus affecting the safety of the power battery pack. Utility Model Content

[0005] The purpose of this application is to prevent the heat generated by the thermally runaway battery cell from being conducted to the bottom wall of adjacent battery cells when one or more battery cells in the power battery pack experience thermal runaway, thereby avoiding a chain reaction of thermal runaway problems caused by overheating of the bottom of normal battery cells and thus improving the safety of the power battery pack.

[0006] To achieve the above objectives, this application provides a battery pack.

[0007] This application further discloses a power battery pack.

[0008] The battery pack according to this application includes: a battery heat insulation unit, the battery heat insulation unit including: a separator, the separator having a separator plate, and a battery cell fixedly connected to at least one side of the separator plate along the thickness direction; the battery cell includes a cell and a battery casing, the cell being disposed inside the battery casing, the bottom of the electrode of the cell being spaced apart from the bottom wall of the battery casing along the height direction of the battery cell, the battery casing having a first sidewall opposite to the separator plate, a heat-insulating groove being provided at the connection between the first sidewall and the bottom wall of the battery casing, the heat-insulating groove being recessed into the battery casing along the thickness direction of the separator plate, the heat-insulating groove being located below the cell; the distance between the bottom of the electrode of the cell and the bottom wall of the battery casing in the height direction of the separator plate is Hmm, the distance between the bottom of the electrode of the cell and the heat-insulating groove in the height direction of the separator plate is hmm, the thickness of the separator plate is dmm, and Hmm, hmm and dmm satisfy the relationship: 0.1≤(Hmm-hmm) / dmm≤5.

[0009] According to the battery pack of this application, by providing a heat-insulating groove at the bottom of the battery casing of the battery insulation unit, when one or more battery cells in the power battery pack experience thermal runaway, and the separator is affected by the adjacent environment to conduct heat, the cavity in the heat-insulating groove can prevent heat from being conducted from the separator to the bottom of the battery casing, thereby reducing the temperature at the bottom of the battery casing. This can help prevent the battery cells from overheating and experiencing thermal runaway, thereby improving the safety of the power battery pack.

[0010] The power battery pack according to this application includes the aforementioned battery pack.

[0011] According to the power battery pack of this application, the power battery pack is provided with a battery pack, which includes a battery heat insulation unit. By providing a heat-insulating groove at the bottom of the battery casing of the battery heat insulation unit, when one or more battery cells in the power battery pack experience thermal runaway, and the separator is affected by the adjacent environment to conduct heat, the cavity in the heat-insulating groove can prevent heat from being conducted from the separator to the bottom of the battery casing, thereby reducing the temperature at the bottom of the battery casing. This can help prevent the battery cells from overheating and experiencing thermal runaway, thereby improving the safety of the power battery pack. Attached Figure Description

[0012] Figure 1 This is a front view of the battery heat insulation unit according to an embodiment of this application; Figure 2 This is a cross-sectional view of the battery heat insulation unit according to an embodiment of this application; Figure 3 yes Figure 2 A magnified view of a section at point A in the middle; Figure 4This is a schematic diagram of the separator in an embodiment of this application; Figure 5 This is a schematic diagram of a power battery pack according to an embodiment of this application.

[0013] In the picture, 1000 refers to the power battery pack. 100. Battery heat insulation unit; 200. Housing; 1. Separator; 11. Separator plate; 111. Extension; 12. Extension plate; 2. Battery cell; 21. Battery cell; 211. Tab; 22. Battery casing; 221. First sidewall; 222. Heat-insulating groove. Detailed Implementation

[0014] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but are not intended to limit the scope of this application.

[0015] It should be noted that the battery cell 2 disclosed below can store chemical energy and controllably convert chemical energy into electrical energy. In the recyclable battery cell 2, the active material can be activated by charging after discharge and can continue to be used. The battery cell 2 includes a battery casing 22 and a cell 21 disposed in the battery casing 22.

[0016] Cell 21 is the component within battery cell 2 where electrochemical reactions occur; it is the smallest unit within battery cell 2 capable of performing electrochemical reactions such as charging / discharging. Cell 21 typically includes a positive electrode, a negative electrode, and a separator. Lithium-ion cell 21 primarily operates by the insertion and extraction of lithium ions between the positive and negative electrodes. In cuboid cell 21, thin film structures are wound or stacked into an electrode assembly with a roughly cuboid shape.

[0017] The battery casing 22 is a component used to provide a receiving space to house the battery cell 21 and other components and isolate them from the outside environment. The battery casing 22 includes a body with an opening at at least one end and a receiving cavity. The opening of the battery casing 22 can be closed by a cover plate to seal and isolate the internal environment of the battery cell 21 from the external environment. The battery casing 22 can be made of materials such as copper, iron, aluminum, stainless steel, or aluminum alloy.

[0018] The cold plate is used for heat exchange with the battery cell 2. Specifically, by bringing the cold plate into contact with the battery cell 2, and when a temperature difference exists between the cold plate and the battery cell 2, heat can be conducted between the cold plate and the battery cell 2 to regulate the temperature of the battery cell 2. The cold plate can be constructed as a liquid-cooled plate, an air-cooled plate, or a phase-change cold plate, etc. The liquid-cooled plate has liquid cooling channels, and in some specific embodiments, the shape of the liquid cooling channels can be "U", "U-shaped", or "S-shaped, etc. Optionally, the liquid-cooled plate also includes an inlet and an outlet, both of which are connected to the liquid cooling channels. The inlet and outlet are used for the inlet and outlet of the heat exchange medium, respectively. The liquid-cooled plate can be made of a material with a certain hardness and strength (such as stainless steel), so that the liquid-cooled plate is not easily deformed when the battery cell 2 is subjected to compression and impact, which can give the cell 21 higher structural strength and thus improve the safety performance of the battery cell 2.

[0019] The phase change cold plate can contain a refrigerant, which cools the battery cell 2 through the phase change of the refrigerant. The refrigerant can be gas, solid, or liquid. Liquid refrigerants can also contain liquids with high specific heat capacity, such as water, as coolants to achieve liquid cooling of the battery cell 2.

[0020] A heat insulation pad is placed between two adjacent battery cells 2. The heat insulation pad prevents heat conduction between the two adjacent battery cells 2, thereby preventing the thermal runaway of some battery cells 2 from being transferred to adjacent battery cells, and thus suppressing heat propagation within the battery pack or power battery module 1000. The outer surface of the heat insulation pad can be made of composite materials, such as epoxy resin pads, or other materials with good thermal insulation properties. The main structure of the heat insulation pad is made of aerogel and a porous fiber substrate. The aerogel can be an inorganic porous aerogel material such as silica, and the porous fiber substrate includes at least one of pre-oxidized fiber felt, glass fiber felt, and ceramic fiber felt. Because inorganic porous aerogel materials such as silica have extremely low thermal conductivity and good heat resistance, aerogel liquid can also be used as the main structure material of the heat insulation pad.

[0021] In other embodiments, the heat insulation pad can be constructed as a composite heat insulation pad, which consists of an encapsulation layer and a phase change material layer. The encapsulation layer is an aluminum-plastic film or a polymer encapsulation film. The phase change material can be a solid phase change material, a liquid phase change material, a solid-liquid mixed phase change material, or a semi-solid phase change material. Optionally, the phase change material includes, but is not limited to, water of crystallization and salt, phase change molten salt, paraffin wax, silicone oil, silica-alumina sol, fatty acids, alcohols, and other substances that can undergo phase change and absorb heat.

[0022] like Figures 1-5As shown in the illustration, this application discloses a battery pack, which includes a battery heat insulation unit 100. Each battery pack may include one battery heat insulation unit 100, or each battery pack may be formed by sequentially splicing multiple battery heat insulation units 100. These multiple battery heat insulation units 100 are arranged sequentially in a single-row-multiple-column, multi-row-single-column, or multi-row-multiple-column arrangement to form the battery pack. Furthermore, the battery pack is disposed within a power battery pack 1000, which may include one battery pack, or the power battery pack 1000 may be formed by sequentially splicing multiple battery packs. The power battery pack 1000 is installed in a vehicle and is used to supply power to the vehicle.

[0023] like Figures 1-5 As shown, the battery heat insulation unit 100 according to an embodiment of this application includes: a separator 1, the separator 1 having a separator plate 11, and a battery cell 2 fixedly connected to at least one side of the separator plate 11 along the thickness direction of the separator plate 11. The thickness direction of the separator plate 11 can be indicated by... Figure 1 The left and right directions in the middle, that is to say Figure 1 A battery cell 2 is fixedly connected to the left side of the middle partition 11, or Figure 1 A battery cell 2 is fixedly connected to the right side of the middle partition 11, or Figure 1 Battery cells 2 are fixedly connected to both the left and right sides of the middle partition 11. Battery cells 2 are the smallest power supply units in the power battery pack 1000.

[0024] Furthermore, the battery cell 2 includes a cell 21 and a battery casing 22. The cell 21 is disposed within the battery casing 22. In this application, the battery cell 2 adopts a stacked configuration, with multiple electrodes of the cell 21 stacked sequentially along the thickness direction of the electrodes. A separator is sandwiched between adjacent positive and negative electrodes. The battery casing 22 is approximately square in shape. The bottom of the electrodes of the cell 21 and the bottom wall of the battery casing 22 are spaced apart along the height direction of the battery cell 2. The battery casing 22 has a first sidewall 221 opposite to the separator 11. In some preferred embodiments, when the battery casing 22 is a square casing, the two opposite sidewalls with the largest area among the multiple sidewalls of the battery casing 22 are used to be fixedly connected to the separator 11. That is, the first sidewall 221 is the sidewall with the largest area of ​​the battery casing 22. At this time, the thickness direction of the battery casing 22 is consistent with the thickness direction of the separator 11. In this way, when the battery casing 22 and the separator 11 abut against each other, and the separator 11 conducts heat into the battery cell 2, the heat can be easily conducted along the electrode surface to all parts of the cell 21. This can minimize the local accumulation of heat in the battery cell 2 and reduce the risk of thermal runaway of the battery cell 2 after being affected by the surrounding environment of the battery insulation unit 100.

[0025] A heat-insulating groove 222 is provided at the connection between the first sidewall 221 and the bottom wall of the battery housing 22. The heat-insulating groove 222 is recessed into the battery housing 22 along the thickness direction of the separator 11. The heat-insulating groove 222 is located below the cell 21. By providing the heat-insulating groove 222 at the bottom of the battery housing 22, when one or some battery cells 2 in the power battery pack 1000 experience thermal runaway, and the separator 1 conducts heat due to the influence of the adjacent environment, the cavity in the heat-insulating groove 222 can prevent heat from being conducted from the separator 1 to the bottom of the battery housing 22. This can reduce the temperature at the bottom of the battery housing 22, thereby preventing the battery cells 2 from overheating and experiencing thermal runaway, and thus improving the safety of the power battery pack 1000.

[0026] And, as Figure 2 , Figure 3 As shown, the distance between the bottom of the electrode of the cell 21 and the bottom wall of the battery casing 22 in the height direction of the separator 11 is H mm, and the distance between the bottom of the electrode of the cell 21 and the heat-insulating groove 222 in the height direction of the separator 11 is h mm. It should be noted that the height direction of the separator 11 can refer to... Figure 1 The thickness of the separator 11 is dmm, and Hmm, hmm, and dmm satisfy the relationship: 0.1≤(Hmm-hmm) / dmm≤5. When the calculated value of the above relationship is too small (i.e., the difference between the spacing Hmm and the spacing hmm is too small), or the thickness dmm of the separator 11 is too large, resulting in a calculated value less than 0.1, the heat-insulating groove 222 occupies too little space at the bottom of the battery casing 22, and the heat conduction efficiency of the separator 11 to the bottom of the battery casing 22 is too high. In this case, the heat-insulating effect of the heat-insulating groove 222 is not obvious, which can easily cause overheating at the bottom of the battery cell 2 and lead to thermal runaway.

[0027] When the calculated value of the above relationship is too large, i.e., the difference between the interval distance Hmm and the interval distance hmm is too large, or the thickness dmm of the separator plate 11 is too small, resulting in the calculated value of the above relationship being greater than 5, in order to make the transition between the groove wall of the heat-insulating groove 222 and the outer wall of the battery housing 22 smooth, so that the heat-insulating groove 222 is easy to process on the battery housing 22, the heat-insulating groove 222 needs to occupy too much space at the bottom of the battery housing 22. When the battery heat insulation unit 100 is installed in the power battery pack 1000, and the battery cell 2 is fixedly connected to the bottom plate of the outer housing 200 of the power battery pack 1000, such a setting will result in the connection area between the bottom wall of the battery housing 22 and the bottom plate being too small, and the connection area between the side wall of the battery housing 22 and the separator plate 11 being too small, resulting in the connection strength between the battery housing 22 and the bottom plate, and between the battery housing 22 and the separator plate 11 being too low. During the use of the power battery pack 1000, the battery cell 2 is easy to fall off the bottom plate, and the battery cell 2 is easy to separate from the separator plate 11. Therefore, when designing the battery housing 22, by ensuring that the calculated value of the above relationship is between 0.1 and 5, the heat-insulating groove 222 can provide limited heat insulation, and also ensure that there is sufficient connection strength between the battery housing 22 and the base plate, and between the battery housing 22 and the partition plate 11.

[0028] In some preferred embodiments, the distance Hmm between the bottom of the electrode of the cell 21 and the bottom wall of the battery casing 22 in the height direction of the separator 11, the distance hmm between the bottom of the electrode of the cell 21 and the heat-insulating groove 222 in the height direction of the separator 11, and the thickness dmm of the separator 11 satisfy the following relationship: 0.5≤(Hmm-hmm) / dmm≤3. This arrangement allows for a more reasonable placement of the heat-insulating groove 222 on the battery cell 2, improves the heat-insulating effect of the heat-insulating groove 222, and ensures a higher connection strength between the battery casing 22 and the base plate, and between the battery casing 22 and the separator 11.

[0029] Furthermore, such as Figure 2 , Figure 3 As shown, the interval distances Hmm and hmm satisfy the relationship: 1mm ≤ (Hmm - hmm) ≤ 10mm. Specifically, when the difference between the interval distances Hmm and hmm is too small (less than 1mm), the maximum distance between the wall of the heat-insulating groove 222 and the bottom wall of the battery casing 22 is too small. This results in the heat-insulating groove 222 occupying too little space at the bottom of the battery casing 22, and the cavity formed by the heat-insulating groove 222 being too small. Consequently, the heat-insulating performance of the heat-insulating groove 222 is insufficient to meet the heat-insulating requirements of the battery casing 22. In this case, the heat-insulating effect of the heat-insulating groove 222 is not significant, which can easily cause overheating at the bottom of the battery cell 2 and lead to thermal runaway.

[0030] When the difference between the interval distance Hmm and the interval distance hmm is too large, specifically when the difference between the interval distance Hmm and the interval distance hmm is greater than 10mm, the maximum interval between the groove wall of the heat-insulating groove 222 and the bottom wall of the battery housing 22 is too large, and the heat-insulating groove 222 occupies too much space at the bottom of the battery housing 22, resulting in too small a contact area between the bottom wall of the battery housing 22 and the bottom plate of the power battery pack 1000, causing low connection strength between the battery cell 2 and the bottom plate.

[0031] Therefore, by setting the difference between the spacing Hmm and the spacing hmm to 1mm to 10mm, the heat resistance performance of the heat-insulating groove 222 can be maximized while ensuring that the battery cell 2 is reliably fixed on the base plate.

[0032] Furthermore, the distance Hmm between the bottom of the electrode of the cell 21 and the bottom wall of the battery casing 22 in the height direction of the separator 11 satisfies the relationship: 1.1mm≤Hmm≤15mm. The distance hmm between the bottom of the electrode of the cell 21 and the heat-insulating groove 222 in the height direction of the separator 11 satisfies the relationship: 0.1mm≤hmm≤5mm. The distance Hmm can be selected between 1.1mm and 15mm according to the actual size of the battery casing 22, and the distance hmm can be adaptively adjusted between 0.1mm and 5mm according to the selected value of the distance Hmm. This makes the structural size of the heat-insulating groove 222 match the structural size of the battery casing 22, thereby enabling the heat-insulating groove 222 to meet the heat-insulating requirements of the battery cell 2.

[0033] Specifically, when the structural size of the battery casing 22 is too small, the selected value of the interval distance Hmm is small, for example, 1.1mm. At this time, the interval distance hmm can be selected with a smaller value, for example, 0.1mm. The difference between the interval distance Hmm and the interval distance hmm is 1mm, which satisfies the requirements of the above relationship.

[0034] When the structural dimensions of the battery casing 22 are too large, the selected value of the spacing distance Hmm is larger, for example, 15mm. At this time, the spacing distance hmm can be selected with a larger value, for example, 5mm. The difference between the spacing distance Hmm and the spacing distance hmm is 10mm, which satisfies the requirements of the above relationship.

[0035] Furthermore, such as Figure 2 , Figure 3As shown, the thickness dmm of the separator 11 satisfies the relationship: 2mm ≤ dmm ≤ 10mm. Specifically, when the thickness dmm of the separator 11 is too small, specifically when the thickness dmm of the separator 11 is less than 2mm, the heat insulation performance of the separator 11 is limited. Heat can easily be conducted from the side of the separator 11 away from the battery cell 2 to the battery cell 2, causing heat to accumulate on the side wall of the battery casing 22. The side wall temperature of the battery cell 2 becomes too high, which in turn leads to thermal runaway of the battery cell 2.

[0036] When the thickness dmm of the separator 11 is too large, specifically when the thickness dmm of the separator 11 is greater than 10mm, the thermal conductivity of the separator 11 along the thickness direction is poor, and heat is more easily conducted downwards along the height direction of the separator 11, causing local overheating at the bottom of the battery casing 22, which in turn leads to thermal runaway of the battery cell 2. Therefore, by setting the thickness dmm of the separator 11 to 2mm to 10mm, the temperature of the side wall and bottom wall of the battery casing 22 can be balanced, thereby preventing thermal runaway caused by local overheating of the battery cell 2.

[0037] Furthermore, in some embodiments of this application, the partition plate 11 is constructed as a cold plate, with a heat exchange channel provided inside the cold plate, and an inlet and an outlet connected to the heat exchange channel on the outer wall surface of the cold plate. Both the inlet and the outlet are connected to an external cold source, which can provide a heat exchange medium to the cold plate. After the heat exchange medium flows into the heat exchange channel from the inlet, the heat exchange medium exchanges heat with the inner wall of the heat exchange channel, and the cold plate exchanges heat with the battery cell 2. The heat is conducted between the battery cell 2 and the heat exchange medium through the cold plate, thereby adjusting the working temperature of the heat exchange medium.

[0038] It should be noted that the heat exchange medium can be air or coolant, and the temperature of the heat exchange medium can be lower than the current temperature of the battery cell 2. By exchanging heat with the battery cell 2 through the heat exchange medium, the operating temperature of the battery cell 2 can be reduced, thereby preventing the battery cell 2 from overheating and thermal runaway. Alternatively, the temperature of the heat exchange medium can be higher than the current temperature of the battery cell 2. When the vehicle is in a cold environment, if the vehicle is stationary for a long time, or when the power battery pack 1000 is charging at a low temperature, the heat exchange medium can exchange heat with the battery cell 2 to increase the operating temperature of the battery cell 2, thereby reducing the power loss of the battery cell 2 and allowing the battery cell 2 to reach the charging temperature requirement more quickly.

[0039] Furthermore, when the separator 11 is constructed as a cold plate, the thickness dmm of the cold plate satisfies the relationship: 3mm ≤ dmm ≤ 8mm. To improve the heat exchange efficiency between the battery casing 22 and the heat exchange medium, the cold plate has strong thermal conductivity. To reduce the heat conducted from the cold plate to the bottom of the battery casing 22, the thickness dmm of the cold plate can be adaptively reduced. Moreover, when the thickness dmm of the cold plate is too small, specifically when the thickness dmm is less than 3mm, the heat conduction speed from the side of the cold plate away from the battery cell 2 to the side closer to the battery cell 2 is faster. When the temperature on one side of the cold plate changes drastically, the battery casing 22 on the other side of the cold plate will receive and accumulate a large amount of heat, leading to thermal runaway of the battery cell 2.

[0040] When the thickness dmm of the cold plate is too large, specifically when the thickness dmm is greater than 8mm, heat on the cold plate is more easily conducted to the bottom of the cold plate, causing heat to accumulate at the bottom of the battery casing 22, which can lead to thermal runaway of the battery cell 2. Therefore, by setting the thickness dmm of the cold plate to 3mm to 8mm, the heat received by the side walls and bottom walls of the battery casing 22 can be evenly distributed, preventing local overheating of the battery casing 22 and thus preventing thermal runaway of the battery cell 2.

[0041] In other embodiments, the separator 11 is configured as a heat insulation pad with a heat insulation coefficient of KW / (m·K). KW / (m·K) and dmm satisfy the following relationships: 0.025W / (m·K)≤KW / (m·K)≤0.8W / (m·K); 2mm≤dmm≤10mm. The heat insulation pad effectively prevents heat from being conducted from one side to the other. By setting the separator 11 as a heat insulation pad, it can prevent heat from being conducted from the side away from the battery cell 2 to the side closer to the battery cell 2, and it can also prevent heat from being conducted towards the bottom of the battery casing 22, thereby reducing the heat conducted to the battery casing 22.

[0042] When the thermal insulation coefficient KW / (m·K) of the heat insulation pad is too small, and / or the thickness dmm of the heat insulation pad is too small, specifically when the thermal insulation coefficient KW / (m·K) of the heat insulation pad is less than 0.025W / (m·K), and / or the thickness dmm of the heat insulation pad is less than 2mm, the thermal insulation performance of the heat insulation pad is poor, and the heat conducted to the battery casing 22 through the heat insulation pad is likely to cause thermal runaway of the battery cell 2.

[0043] When the thermal insulation coefficient KW / (m·K) of the heat insulation pad is too large, and / or the thickness dmm of the heat insulation pad is too large, specifically when the thermal insulation coefficient KW / (m·K) of the heat insulation pad is greater than 0.8 W / (m·K), and / or the thickness dmm of the heat insulation pad is greater than 10 mm, the heat insulation performance of the heat insulation pad is too strong, which will affect the heat dissipation of the battery cell 2, thereby causing the heat generated by the battery cell 2 to accumulate and cause thermal runaway of the battery cell 2. In addition, when the thickness of the heat insulation pad is too large, the installation space occupied by the heat insulation pad in the outer shell 200 of the power battery pack 1000 is too large, which reduces the energy density of the power battery pack 1000.

[0044] Therefore, by setting the thermal insulation coefficient KW / (m·K) of the heat insulation pad to 0.025W / (m·K)~0.8W / (m·K) and the thickness dmm of the heat insulation pad to 2mm~10mm, while ensuring that the heat insulation pad can effectively prevent heat conduction from the outside of the battery cell 2 to the battery casing 22, the installation space occupied by the heat insulation pad in the outer casing 200 of the power battery pack 1000 can be made more suitable. It should be understood that when the thermal insulation performance of the heat insulation pad is consistent, the larger the thermal insulation coefficient KW / (m·K) of the heat insulation pad, the smaller the thickness dmm of the heat insulation pad. Therefore, after adjusting the thermal insulation coefficient KW / (m·K) of the heat insulation pad according to the actual design requirements, the thickness dmm of the heat insulation pad can be adjusted adaptively to achieve a balance between the thermal insulation coefficient KW / (m·K) and the thickness dmm of the heat insulation pad.

[0045] like Figure 1 As shown, in some embodiments of this application, along the first direction of the battery cell 2, one end of the heat-insulating groove 222 extends to the end wall of one end of the battery housing 22, and the other end of the heat-insulating groove 222 extends to the end wall of the other end of the battery housing 22. The first direction of the battery cell 2, the thickness direction of the separator 11, and the height direction of the battery cell 2 are arranged perpendicularly to each other. The first direction of the battery cell 2 can refer to the length direction of the battery cell 2. That is, the heat-insulating groove 222 penetrates the battery housing 22 along the length direction of the battery housing 22. This can significantly reduce the contact area between the bottom of the battery housing 22 and the separator 11, thereby improving the heat-insulating effect of the heat-insulating groove 222.

[0046] The distance between the edge of the heat-insulating groove 222 on the bottom wall of the battery housing 22 and the first side wall 221 is W1mm, and the thickness of the battery cell 2 is W2mm. W1mm and W2mm satisfy the relationship: 7mm≤W2mm-W1mm≤77mm. When the difference between the thickness of the battery cell 2 W2mm and the distance W1mm is too small, specifically, when the difference between the thickness of the battery cell 2 W2mm and the distance W1mm is less than 7mm, the contact area between the bottom wall of the battery housing 22 and the base plate is too small, the flatness of the bottom of the battery housing 22 is poor, the bonding strength between the battery housing 22 and the base plate is low, and the battery cell 2 is easy to fall off the base plate, resulting in poor working reliability of the power battery pack 1000.

[0047] When the difference between the thickness W2mm and the spacing W1mm of the battery cell 2 is too large—specifically, when the difference is greater than 77mm—the space occupied by the heat-insulating groove 222 on the bottom wall of the battery cell 2 is too small. The heat-insulating effect of the groove 222 is limited, and the separator 11 easily conducts heat to the bottom wall of the battery casing 22, leading to thermal runaway of the battery cell 2. Therefore, by setting the difference between the thickness W2mm and the spacing W1mm of the battery cell 2 to 7mm to 77mm, the heat-insulating effect of the heat-insulating groove 222 can be maximized while ensuring reliable adhesion of the battery cell 2 to the base plate.

[0048] like Figure 2 As shown, in some embodiments of this application, the battery cell 21 has tabs 211 formed on its top. The tabs 211 are located on the top of the battery cell 21 and extend towards the top wall of the battery casing 22. That is, the tabs 211 and the bottom wall of the battery casing 22 are spaced apart along the height of the battery cell 2. During operation, such as charging or discharging, the tabs 211 generate a large amount of heat. By separating the tabs 211 from the bottom wall of the battery casing 22, the heat has a smaller impact on the temperature of the tabs 211 when conducted from the separator 11 to the bottom wall of the battery casing 22, thus preventing overheating of the tabs 211 and thermal runaway of the battery cell 2. Furthermore, the spaced arrangement of the tabs 211 and the separator 11 makes it less likely for the separator 11 to directly conduct heat to the tabs 211, further preventing overheating of the tabs 211 and thermal runaway of the battery cell 2.

[0049] like Figure 5As shown, in some embodiments of this application, the battery heat insulation unit 100 is disposed within the power battery pack 1000. The power battery pack 1000 also includes an outer shell 200, which includes a base plate located below the battery housing 22. The battery housing 22 is bonded to the base plate. A heat-insulating space is formed within the heat-insulating groove 222, and an adhesive layer is provided between the battery housing 22 and the base plate. The adhesive layer can be formed by the solidification of thermally conductive adhesive. The battery housing 22 is indirectly fixed to the base plate through the adhesive layer, thereby preventing the battery cell 2 from shaking within the power battery pack 1000. Furthermore, by exchanging heat with the battery housing 22 and the base plate respectively, the adhesive layer can conduct the heat generated by the battery cell 2 to the base plate, and then the heat can be dissipated from the base plate to the external environment to reduce the operating temperature of the battery cell 2.

[0050] The heat-insulating space is partially filled with an adhesive layer and has a cavity. During the heat conduction from the separator 11 to the bottom wall of the battery casing 22, the heat needs to pass through multiple media in sequence. The heat conduction efficiency is poor when conducting between media of two different phases, which can further reduce the heat conducted from the separator 11 to the bottom wall of the battery casing 22, thereby further preventing thermal runaway of the battery cell 2.

[0051] Furthermore, at least a portion of the outer wall of the heat-insulating groove 222 is covered with an adhesive layer. The wall of the heat-insulating groove 222 is bonded to the base plate through the adhesive layer. This increases the bonding area between the battery housing 22 and the base plate, thereby improving the bonding strength between them and further preventing the battery cells 2 from detaching from the base plate. The adhesive layer covering the wall of the heat-insulating groove 222 can be formed by the solidification of thermally conductive adhesive poured into the outer shell 200 of the power battery pack 1000. Before solidification, the thermally conductive adhesive flows to the bottom of the outer shell 200. Since the heat-insulating groove 222 is located on the bottom wall of the battery housing 22 and is close to the base plate, the thermally conductive adhesive can flow into the heat-insulating groove 222.

[0052] Furthermore, the elastic modulus of the adhesive layer is E, which satisfies the relationship: 50MPa≤EMPa≤5000MPa. When the elastic modulus E of the adhesive layer is too small, for example, less than 50MPa, even though the bottom wall of the battery casing 22 and the groove wall of the heat-insulating groove 222 are both connected to the base plate through the adhesive layer, the battery casing 22 is still prone to detaching from the base plate due to the low bonding strength between them. When the elastic modulus E of the adhesive layer is too large, for example, greater than 5000MPa, the adhesive layer becomes too brittle and prone to breakage, causing the battery cell 2 to detach from the base plate. Therefore, by setting the elastic modulus E of the adhesive layer to 50MPa~5000MPa, it can be ensured that the battery cell 2 is reliably bonded to the base plate.

[0053] In some embodiments of this application, along the height direction of the battery housing 22, the upper end of the partition plate 11 extends to the upper edge of the battery housing 22, and the lower end of the partition plate 11 extends to the edge of the heat-insulating groove 222 on the side wall of the battery housing 22 opposite to the partition plate 11. That is, the height dimension of the partition plate 11 matches the height dimension of the part of the side wall of the battery housing 22 where the heat-insulating groove 222 is not provided. This arrangement can reduce the space occupied by the partition plate 11 in the power battery pack 1000, which helps to improve the energy density of the power battery pack 1000.

[0054] like Figure 1 , Figure 2 As shown, in some other embodiments of this application, the partition plate 11 is along the height direction of the partition plate 11 (i.e. Figure 1 The partition plate 11 extends to the outside of the heat-insulating groove 222 in the vertical direction, and at least partially blocks the heat-insulating groove 222 along the thickness direction of the partition plate 11. The portion of the partition plate 11 extending to the outside of the heat-insulating groove 222 is constructed as an extension 111 of the partition plate 11, and the height of the top end of the extension 111 is equal to the height of the edge of the heat-insulating groove 222 on the side wall of the battery casing 22 opposite to the partition plate 11.

[0055] By utilizing the portion of the separator 11 located outside the heat-insulating groove 222 to shield the heat-insulating groove 222, when the temperature on the side of the separator 11 away from the battery cell 2 changes drastically, or when an adjacent battery cell 2 catches fire, the separator 11 can prevent heat from being directly conducted from the side of the separator 11 away from the battery cell 2 into the heat-insulating groove 222. It can also prevent flames from rushing into the heat-insulating groove 222, thereby further preventing the temperature inside the heat-insulating groove 222 from becoming too high and affecting the thermal runaway of the battery cell 2. It can also prevent the flames from burning the inner wall of the heat-insulating groove 222, causing the local temperature of the battery cell 2 to become too high, thereby further improving the safety of the battery cell 2 in use.

[0056] Furthermore, such as Figure 2 As shown, the bottom wall height of the separator 11 is lower than the bottom wall height of the battery casing 22. The separator 1 also includes an extension plate 12, which is fixedly disposed at the bottom end of the separator 11. In some specific embodiments, the extension plate 12 and the separator 11 are constructed as an integral part, that is, the extension plate 12 and the separator 11 are made by integral molding. In other embodiments, the extension plate 12 and the separator 11 are constructed as independent components, and the extension plate 12 is fixedly installed at the bottom end of the separator 11.

[0057] Along the thickness direction of the separator 11, the extension plate 12 extends away from the separator 11. The extension plate 12 is located outside the heat-insulating groove 222, along the height direction of the battery cell 2 (i.e., Figure 1 The extension plate 12 (located in the vertical direction) provides at least partial shielding and heat-insulating grooves 222. When the battery heat insulation unit 100 is disposed within the power battery pack 1000, the extension plate 12 also engages with and is fixedly connected to the bottom plate of the power battery pack 1000. Specifically, the extension plate 12 and the bottom plate are bonded together using thermally conductive adhesive. The extension plate 12 increases the contact area between the separator 1 and the bottom plate, thereby improving the connection strength between the separator 1 and the bottom plate. This reduces the movement of the separator 1 within the outer casing 200 of the power battery pack 1000 during use, improving the operational stability of the power battery pack 1000.

[0058] Furthermore, by increasing the contact area between the separator 1 and the base plate, the heat exchange efficiency between the separator 1 and the base plate can be improved. When a battery cell 2 in contact with the separator 1 experiences thermal runaway, the heat generated by the battery cell 2 can be conducted to the base plate through the separator 1, and then to the external environment through the base plate. This reduces the temperature inside the power battery pack 1000, minimizing the spread of thermal runaway within the battery pack and thus reducing the size of the damaged area in the power battery pack 1000. In addition, after the large amount of heat generated by the battery cell 2 is conducted to the external environment through the base plate, the temperature of the separator 1 decreases, minimizing the risk of overheating and thermal runaway of adjacent battery cells 2, further improving the safety of the battery pack.

[0059] like Figure 3As shown, in some embodiments of this application, the extension dimension of the extension plate 12 along the thickness direction of the separator 11 is W3mm, where W3mm satisfies the relationship: 2mm≤W3mm≤80mm. Specifically, when the extension dimension of the extension plate 12 is too small (less than 2mm), it can be considered to have no heat conduction effect, making it difficult for it to quickly conduct heat from the separator 11 to the base plate. Conversely, when the extension dimension of the extension plate 12 is too long (greater than 80mm), its excessive protrusion below the battery casing 22 affects the flatness of the bottom surface of the battery insulation unit 100. This can cause the battery cells 2 to be misaligned within the power battery pack 1000, affecting the connection accuracy between the various connectors (such as aluminum busbars and temperature detection components) and the battery cells 2 within the power battery pack 1000. Therefore, by designing the extension size of the extension plate 12 to be 2mm to 80mm, the battery cell 2 can be stably installed on the base plate, and the extension plate 12 can effectively conduct the heat of the separator 11 to the base plate.

[0060] Furthermore, the extension plate 12 extends to abut against the bottom wall of the battery housing 22. This arrangement limits the relative position between the battery housing 22 and the extension plate 12, allowing the extension plate 12 to support and limit the battery housing 22, thereby improving the assembly accuracy between the battery housing 22 and the separator 1, and further improving the product consistency of the battery heat insulation unit 100 within the power battery pack 1000.

[0061] like Figure 5 As shown, in some embodiments of this application, the battery pack includes a plurality of battery heat insulation units 100, which are arranged sequentially along a second direction, wherein the second direction is opposite to the thickness direction of the separator 11. Figure 1 In the same left-right direction, at least two adjacent separators 1 are sandwiched between a battery cell 2, and at least two adjacent battery cells 2 are sandwiched between a separator 1. That is to say, at least two battery cells 2 are separated by separators 11. In the event of thermal runaway of a battery cell 2, this arrangement ensures that the heat generated by the battery cell 2 is blocked by the separators 11 when it is conducted to the normal battery cells 2 on both sides of the battery cell 2. The heat generated by the battery cell 2 is difficult to diffuse outward, thereby preventing a chain reaction of thermal runaway of battery cells 2 in the battery pack, and thus effectively improving the safety of the battery pack.

[0062] Furthermore, the battery cell 2 sandwiched between two adjacent separators 1 has a battery casing 22 provided with two heat-insulating grooves 222, the two heat-insulating grooves 222 being along the second direction (i.e. Figure 1The heat-insulating grooves 222 are spaced apart in the left and right directions, and each heat-insulating groove 222 is respectively positioned opposite to the separator 1 on the corresponding side of the battery housing 22. By providing heat-insulating grooves 222 on both sides of the battery housing 22, when the ambient temperature on either side of the battery cell 2 rises too high along the second direction, the heat in the battery cell 2 can be limited by the heat-insulating groove 222 on the corresponding side to prevent heat from being conducted to the bottom of the battery cell 2 through the separator 11. This can prevent local overheating of the bottom of the battery cell 2 from causing thermal runaway of the battery cell 2, and further improve the safety of the battery pack.

[0063] Correspondingly, when both sides of the separator 1 are connected to battery cells 2, extension plates 12 are provided on both sides of the separator 11. The two extension plates 12 extend towards the corresponding battery cell 2. In this case, the separator 1 can be constructed as a T-shaped plate. It should be noted that when one side of the separator 1 is connected to a battery cell 2 and the other side is not connected to a battery cell 2, such as when the separator 1 is located at the edge of the battery pack, the separator 1 can be constructed as an L-shaped plate to reduce the unnecessary occupation of the installation space within the power battery pack 1000 by the extension plates 12.

[0064] Based on this, such as Figure 5 As shown, this application further discloses a power battery pack 1000, which includes the battery pack of the above embodiment. According to the power battery pack 1000 of this application embodiment, the power battery pack 1000 is provided with a battery pack, and the battery pack includes a battery heat insulation unit 100. By providing a heat-insulating groove 222 at the bottom end of the battery housing 22 of the battery heat insulation unit 100, when one or more battery cells 2 in the power battery pack 1000 experience thermal runaway, and the separator 1 conducts heat due to the influence of the adjacent environment, the cavity in the heat-insulating groove 222 can prevent heat from being conducted from the separator 1 to the bottom end of the battery housing 22, thereby reducing the temperature at the bottom end of the battery housing 22. This can minimize the risk of the battery cell 2 overheating and experiencing thermal runaway, thereby improving the safety of the power battery pack 1000.

[0065] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of this application, and these improvements and substitutions should also be considered within the scope of protection of this application.

Claims

1. A battery pack, characterized in that, include: The battery heat insulation unit includes: A separator having a separator plate, wherein a battery cell is fixedly connected to at least one side of the separator plate along the thickness direction; The battery cell includes a battery cell and a battery casing. The battery cell is disposed inside the battery casing. The bottom of the electrode of the battery cell and the bottom wall of the battery casing are spaced apart along the height direction of the battery cell. The battery casing has a first sidewall opposite to the partition plate. A heat-insulating groove is provided at the connection between the first sidewall and the bottom wall of the battery casing. The heat-insulating groove is recessed into the battery casing along the thickness direction of the partition plate and is located below the battery cell. The distance between the bottom of the electrode of the battery cell and the bottom wall of the battery casing in the height direction of the separator is Hmm, the distance between the bottom of the electrode of the battery cell and the heat-insulating groove in the height direction of the separator is hmm, and the thickness of the separator plate is dmm. Hmm, hmm and dmm satisfy the relationship: 0.1≤(Hmm-hmm) / dmm≤5.

2. The battery pack according to claim 1, characterized in that, The distance Hmm between the bottom of the electrode of the battery cell and the bottom wall of the battery casing in the height direction of the separator, the distance hmm between the bottom of the electrode of the battery cell and the heat-insulating groove in the height direction of the separator, and the thickness dmm of the separator plate also satisfy the following relationship: 0.5≤(Hmm-hmm) / dmm≤3.

3. The battery pack according to claim 1, characterized in that, The distance Hmm between the bottom of the electrode of the battery cell and the bottom wall of the battery casing in the height direction of the separator, and the distance hmm between the bottom of the electrode of the battery cell and the heat-insulating groove in the height direction of the separator, satisfy the following relationship: 1mm≤(Hmm-hmm)≤10mm, 1.1mm≤Hmm≤15mm, 0.1mm≤hmm≤5mm.

4. The battery pack according to any one of claims 2 or 3, characterized in that, The thickness dmm of the partition plate satisfies the following relationship: 2mm≤dmm≤10mm.

5. The battery pack according to claim 4, characterized in that, The partition plate is constructed as a cold plate, and the cold plate has a heat exchange channel inside. The outer wall of the cold plate has an inlet and an outlet that communicate with the heat exchange channel. The thickness dmm of the partition plate satisfies the following relationship: 3mm≤dmm≤8mm.

6. The battery pack according to claim 4, characterized in that, The partition plate is constructed as a heat insulation pad, and the heat insulation coefficient of the heat insulation pad is KW / (m·K). KW / (m·K) and the thickness dmm of the partition plate satisfy the following relationship: 0.025W / (m·K)≤KW / (m·K)≤0.8W / (m·K); 2mm≤dmm≤10mm.

7. The battery pack according to claim 1, characterized in that, Along the first direction of the battery cell, one end of the heat-insulating groove extends to the end wall of one end of the battery housing, and the other end of the heat-insulating groove extends to the end wall of the other end of the battery housing, wherein the first direction of the battery cell, the thickness direction of the separator, and the height direction of the battery cell are arranged perpendicularly to each other. The distance between the edge of the heat-insulating groove on the bottom wall of the battery casing and the first side wall is W1mm, and the thickness of the battery cell is W2mm. W1mm and W2mm satisfy the relationship: 7mm≤W2mm-W1mm≤77mm.

8. The battery pack according to claim 1, characterized in that, The battery cell has tabs, which are located on the top of the battery cell and extend toward the top wall of the battery casing. The tabs are spaced apart from the separator plate.

9. The battery pack according to claim 1, characterized in that, The battery heat insulation unit is disposed inside the power battery pack. The power battery pack also includes an outer shell. The outer shell includes a base plate. The base plate is located below the battery housing and the battery housing is bonded to the base plate. A heat-insulating space is formed in the heat-insulating groove. An adhesive layer is provided between the battery housing and the base plate. A portion of the structure of the adhesive layer is filled in the heat-insulating space, and the heat-insulating space has a cavity.

10. The battery pack according to claim 9, characterized in that, At least a portion of the outer wall of the heat-insulating groove is covered with the adhesive layer, and the elastic modulus of the adhesive layer is EMPa, which satisfies the relationship: 50MPa≤EMPa≤5000MPa.

11. The battery pack according to claim 1, characterized in that, Along the height direction of the battery housing, the upper end of the partition plate extends to the upper edge of the battery housing, and the lower end of the partition plate extends to the edge of the heat-insulating groove on the side wall of the battery housing opposite to the partition plate.

12. The battery pack according to claim 1, characterized in that, The partition plate extends along its height direction to the outside of the heat-insulating groove, and the partition plate at least partially blocks the heat-insulating groove along its thickness direction.

13. The battery pack according to claim 12, characterized in that, The bottom wall of the partition plate is lower than the bottom wall of the battery casing; The separator also includes an extension plate, which is fixedly disposed at the bottom end of the separator. Along the thickness direction of the separator, the extension plate extends away from the separator. The extension plate is located outside the heat-insulating groove so as to at least partially block the heat-insulating groove along the height direction of the battery cell.

14. The battery pack according to claim 13, characterized in that, Along the thickness direction of the partition plate, the extension dimension of the extension plate is W3mm, and W3mm satisfies the relationship: 2mm≤W3mm≤80mm.

15. The battery pack according to claim 14, characterized in that, The extension plate extends to engage with the bottom wall of the battery casing.

16. The battery pack according to claim 1, characterized in that, The battery pack includes a plurality of battery heat insulation units, which are arranged sequentially along a second direction. At least two adjacent separators are sandwiched between a battery cell, and at least two adjacent battery cells are sandwiched between a separator. The second direction is the same as the thickness direction of the separator.

17. The battery pack according to claim 16, characterized in that, The battery cell sandwiched between two adjacent separators has a battery housing with two heat-resistant grooves. The two heat-resistant grooves are spaced apart along the second direction, and each heat-resistant groove is respectively positioned opposite to a separator on the corresponding side of the battery housing.

18. A power battery pack, characterized in that, Includes the battery pack according to any one of claims 1-17.

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