Battery module and battery box with heating function

Abstract

The present invention relates to a battery module and a battery box with a heating function. The battery module with a heating function includes a battery cell, an end plate, and a heating film. The heating film is bonded and fixed to the battery cell. The two ends of the heating film of the battery module of the present invention are connected to the end plate by a connecting piece. The stopping structure on the connecting piece can prevent the end of the heating film from warping, thereby improving the fixing effect of the heating film. Compared with the current method of fixing the heating film only by gluing, after the battery module expands, the force on the end of the heating film is unbalanced in the stacking direction of the battery cells, and the end of the heating film is prone to warping. The stopping structure of the present invention can cooperate with the end of the heating film to stop the end of the heating film, so that the end of the heating film does not warp, which solves the technical problem that the heating film is easily fallen off by gluing the heating film to the module to achieve fixation in the existing battery module, thereby reducing the service life of the battery module.

Description

Technical Field

[0001] The invention relates to a battery module and a battery box with a heating function. Background Art

[0002] Existing battery packs are affected by ambient temperature during use, resulting in poor battery discharge capacity at low temperatures. Furthermore, at low temperatures, the conductivity of charged ions within the battery is poor, and the ability to transfer and embed charge within the negative electrode material structure is also poor. During charging at low temperatures, a large number of lithium ions accumulate on the negative electrode surface and cannot be embedded. Electron deposition on the electrode surface causes lithium accumulation, and lithium metal is prone to uneven crystal growth. If dendrites grow large enough, they can pierce the separator, creating a direct connection between the positive and negative electrodes and forming an internal short circuit in the battery cell.

[0003] Installing a heating film inside the battery box can solve the problem of charging and discharging in low-temperature environments. Currently, the heating film is usually bonded to the side of the battery cell. When the heating film is powered, the heat generated by the heating film heats the battery cell, raising the temperature inside the battery box. Because the battery cell expands during charging and discharging, the heating film attached to the module is subject to the alternating stress of the module expansion and easily falls off the module, shortening the battery module's service life. Summary of the Invention

[0004] The object of the present invention is to provide a battery module with a heating function to solve the technical problem in existing battery modules that the heating film is easily detached by being adhered to the module to achieve fixation, thereby reducing the service life of the battery module.

[0005] Another object of the present invention is to provide a battery box using the battery module to solve the technical problem of short battery box life caused by the easy shedding of the heating film in the battery module.

[0006] To achieve the above objectives, the battery module with heating function in the present invention adopts the following technical solutions:

[0007] Battery modules with heating function include:

[0008] A plurality of battery cells are provided, and the plurality of battery cells are stacked in a front-to-back direction to form a battery cell group;

[0009] End plates, arranged at the front and rear ends of the battery cell group;

[0010] A heating film extending in the front-to-back direction and arranged on at least one of the left side and the right side of the battery cell group for heating the battery cells;

[0011] The heating film is bonded and fixed to the battery cell;

[0012] Connecting piece, the ends of the heating film at the front and rear ends of the heating film are connected to the end plates at both ends through the connecting piece, and the connecting piece has a stopping structure for limiting the movement of the ends of the heating film away from the battery cell group.

[0013] Beneficial effect: The two ends of the heating film of the battery module of the present invention are connected to the end plate through a connecting piece. The stopping structure on the connecting piece can prevent the movable end from warping, thereby improving the fixing effect of the heating film. Compared with the current heating film fixing method only by gluing, after the battery module expands, the force on the end of the heating film is unbalanced in the stacking direction of the battery cells, and the end of the heating film is prone to warping. The stopping structure of the present invention can cooperate with the stopping structure of the end of the heating film to prevent the end of the heating film from warping, thereby solving the technical problem in the existing battery module that the heating film is easily fallen off by gluing it to the module to achieve fixation, thereby reducing the service life of the battery module.

[0014] Furthermore, at least one of the front and rear ends of the heating film is a movable end, and the end plate connected to the movable end is a movable end connecting end plate; the movable end and / or the movable end connecting end plate is provided with a long hole or a long groove that slides with the connecting piece in the front and rear directions, so that the movable end and the movable end connecting end plate can move relative to each other in the front and rear directions.

[0015] Beneficial effects: The movable end and / or the long hole or long groove on the movable end connecting end plate enables the movable end and the end plate to move relative to each other, which is convenient for the installation of the heating film and can adapt to the expansion of the battery cell group and is not easy to fall off.

[0016] Furthermore, the connecting piece connected to the movable end connecting end plate is used to press the movable end onto the movable end connecting end plate. The movable end and the movable end connecting end plate move relative to each other in the front-to-back direction when the module expansion force driven to move relative to each other in the front-to-back direction is greater than the maximum static friction force between the two.

[0017] Beneficial effect: Pressing the movable end against the end plate makes the movable end more stable.

[0018] Furthermore, the movable end is provided with the long hole, the connecting piece is clamped on the corresponding end plate, and the stopping structure on the connecting piece is a stopping cap located on the side of the heating film facing away from the battery cell.

[0019] Beneficial effect: The connector is clipped onto the end plate for easy installation.

[0020] Furthermore, one end of the heating film is a positioning fixed end, and the end plate connected to the positioning fixed end is a fixed end connecting end plate. The positioning fixed end is fixed to the fixed end connecting end plate through a connecting piece. A positioning structure is provided between the fixed end connecting end plate and the positioning fixed end, or the fixed end connecting end plate and the positioning fixed end are positioned through a connecting piece.

[0021] Beneficial effect: One end of the heating film is fixed and the other end is movable, which facilitates the positioning and installation of the heating film.

[0022] Furthermore, the heating film is provided with a weak portion, wherein the weak portion is provided with a hole or a slit that passes through both sides of the heating film; or the weak portion is provided with a thinning depression that reduces the film thickness;

[0023] The weak portion extends perpendicular to the arrangement direction of the battery cells and is opposite to the stacking positions of two adjacent battery cells.

[0024] Beneficial effects: When the battery cells are charging and discharging, the two adjacent battery cells will expand, and the spacing between the stacked positions of the battery cells will become larger. Because the side surfaces of the battery cells are relatively fixed to the heating film, when the alternating expansion force is transmitted to the weak part, the opening formed by the holes or seams on the heating film can become larger, and the thinning depressions make the film thickness thinner and easier to deform. Therefore, when the heating film is subjected to external force, the parts of the heating film on both sides of the weak part will move away from each other. The influence of the alternating expansion force on the rest of the heating film is weakened by the elongation and deformation of the weak part. The rest of the part is not easy to debond from the battery cells. The deformation capacity of the heating film can be improved without changing the material of the heating film, thereby reducing production costs.

[0025] Furthermore, two adjacent weak portions in the direction of cell arrangement both satisfy the following conditions: the hole, slit or thinning depression on one weak portion is arranged upward, and the hole, slit or thinning depression on the other weak portion is arranged downward.

[0026] Beneficial effect: When the heating film is affected by the alternating expansion force, the deformation of the upper part of the heating film is relatively balanced with the deformation of the lower part of the heating film, thereby avoiding the heating film being stretched into a trapezoidal or inverted trapezoidal shape, and avoiding stress concentration in the heating film that causes the heating film to break, thereby improving the ability of the heating film to resist the alternating expansion force.

[0027] Furthermore, heating films are provided on the left and right sides of the battery cell group. Of the two weak parts on the left and right heating films that are opposite to the stacking positions of the same pair of adjacent battery cells, the hole or slit or thinning depression on one is arranged upward, and the hole or slit or thinning depression on the other is arranged downward.

[0028] Beneficial effect: This arrangement can stagger the positions where the heating film on the left side of the battery cell and the heating film on the right side of the battery cell are pulled apart and deformed by the alternating expansion force in the vertical direction, avoiding the situation where one end of the battery cell is tight and the other end is relaxed in the vertical direction, so that the heating film can withstand higher alternating expansion forces.

[0029] Furthermore, there is a gap between the weak portion on the heating film and the stacking position of the adjacent battery cells, and the hole or slit on the weak portion communicates with the gap.

[0030] Beneficial effect: When the heating film is subjected to alternating expansion force in the module, it can unload through the holes or seams, and the intervals facilitate the deformation of the heating film.

[0031] The technical solution of the battery box of the present invention:

[0032] The battery box includes a box body and a battery module;

[0033] The battery module is installed in the box and includes:

[0034] A plurality of battery cells are provided, and the plurality of battery cells are stacked in a front-to-back direction to form a battery cell group;

[0035] End plates, arranged at the front and rear ends of the battery cell group;

[0036] A heating film extending in the front-to-back direction and arranged on at least one of the left side and the right side of the battery cell group for heating the battery cells;

[0037] The heating film is bonded and fixed to the battery cell;

[0038] Connecting piece, the ends of the heating film at the front and rear ends of the heating film are connected to the end plates at both ends through the connecting piece, and the connecting piece has a stopping structure for limiting the movement of the ends of the heating film away from the battery cell group.

[0039] Beneficial effect: The two ends of the heating film of the battery module of the present invention are connected to the end plate through a connecting piece. The stopping structure on the connecting piece can prevent the movable end from warping, thereby improving the fixing effect of the heating film. Compared with the current heating film only being fixed by gluing, after the battery module expands, the force on the end of the heating film is unbalanced in the stacking direction of the battery cells, and the end of the heating film is prone to warping. The stopping structure of the present invention can cooperate with the stopping structure of the end of the heating film to prevent the end of the heating film from warping, thereby solving the technical problem of the current battery box having a low lifespan caused by the easy falling off of the heating film in the battery module.

[0040] Furthermore, at least one of the front and rear ends of the heating film is a movable end, and the end plate connected to the movable end is a movable end connecting end plate; the movable end and / or the movable end connecting end plate is provided with a long hole or a long groove that slides with the connecting piece in the front and rear directions, so that the movable end and the movable end connecting end plate can move relative to each other in the front and rear directions.

[0041] Beneficial effects: The movable end and / or the long hole or long groove on the movable end connecting end plate enables the movable end and the end plate to move relative to each other, which is convenient for the installation of the heating film and can adapt to the expansion of the battery cell group and is not easy to fall off.

[0042] Furthermore, the connecting piece connected to the movable end connecting end plate is used to press the movable end onto the movable end connecting end plate. The movable end and the movable end connecting end plate move relative to each other in the front-to-back direction when the module expansion force driven to move relative to each other in the front-to-back direction is greater than the maximum static friction force between the two.

[0043] Beneficial effect: Pressing the movable end against the end plate makes the movable end more stable.

[0044] Furthermore, the movable end is provided with the long hole, the connecting piece is clamped on the corresponding end plate, and the stopping structure on the connecting piece is a stopping cap located on the side of the heating film facing away from the battery cell.

[0045] Beneficial effect: The connector is clipped onto the end plate for easy installation.

[0046] Furthermore, one end of the heating film is a positioning fixed end, and the end plate connected to the positioning fixed end is a fixed end connecting end plate. The positioning fixed end is fixed to the fixed end connecting end plate through a connecting piece. A positioning structure is provided between the fixed end connecting end plate and the positioning fixed end, or the fixed end connecting end plate and the positioning fixed end are positioned through a connecting piece.

[0047] Beneficial effect: One end of the heating film is fixed and the other end is movable, which facilitates the positioning and installation of the heating film.

[0048] Furthermore, the heating film is provided with a weak portion, wherein the weak portion is provided with a hole or a slit that passes through both sides of the heating film; or the weak portion is provided with a thinning depression that reduces the film thickness;

[0049] The weak portion extends perpendicular to the arrangement direction of the battery cells and is opposite to the stacking positions of two adjacent battery cells.

[0050] Beneficial effects: When the battery cells are charging and discharging, the two adjacent battery cells will expand, and the spacing between the stacked positions of the battery cells will become larger. Because the side surfaces of the battery cells are relatively fixed to the heating film, when the alternating expansion force is transmitted to the weak part, the opening formed by the holes or seams on the heating film can become larger, and the thinning depressions make the film thickness thinner and easier to deform. Therefore, when the heating film is subjected to external force, the parts of the heating film on both sides of the weak part will move away from each other. The influence of the alternating expansion force on the rest of the heating film is weakened by the elongation and deformation of the weak part. The rest of the part is not easy to debond from the battery cells. The deformation capacity of the heating film can be improved without changing the material of the heating film, thereby reducing production costs.

[0051] Furthermore, two adjacent weak portions in the direction of cell arrangement both satisfy the following conditions: the hole, slit or thinning depression on one weak portion is arranged upward, and the hole, slit or thinning depression on the other weak portion is arranged downward.

[0052] Beneficial effect: When the heating film is affected by the alternating expansion force, the deformation of the upper part of the heating film is relatively balanced with the deformation of the lower part of the heating film, thereby avoiding the heating film being stretched into a trapezoidal or inverted trapezoidal shape, and avoiding stress concentration in the heating film that causes the heating film to break, thereby improving the ability of the heating film to resist the alternating expansion force.

[0053] Furthermore, heating films are provided on the left and right sides of the battery cell group. Of the two weak parts on the left and right heating films that are opposite to the stacking positions of the same pair of adjacent battery cells, the hole or slit or thinning depression on one is arranged upward, and the hole or slit or thinning depression on the other is arranged downward.

[0054] Beneficial effect: This arrangement can stagger the positions where the heating film on the left side of the battery cell and the heating film on the right side of the battery cell are pulled apart and deformed by the alternating expansion force in the vertical direction, avoiding the situation where one end of the battery cell is tight and the other end is relaxed in the vertical direction, so that the heating film can withstand higher alternating expansion forces.

[0055] Furthermore, there is a gap between the weak portion on the heating film and the stacking position of the adjacent battery cells, and the hole or slit on the weak portion communicates with the gap.

[0056] Beneficial effect: When the heating film is subjected to alternating expansion force in the module, it can unload through the holes or seams, and the intervals facilitate the deformation of the heating film. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic structural diagram of a specific embodiment 1 of a battery module with a heating function according to the present invention;

[0058] Figure 2 Schematic diagram of the installation structure of the movable end connecting end plate and the heating film of the specific embodiment 1 of the battery module with heating function in the present invention;

[0059] Figure 3 This is a structural diagram of the relative positions of the heating films in the specific embodiment 1 of the battery module with heating function of the present invention;

[0060] Figure 4 Schematic diagram of the structure of the heating film at the battery cell stacking position of the specific embodiment 1 of the battery module with heating function of the present invention;

[0061] Figure 5 Schematic diagram of the structure of the heating film in the specific embodiment 1 of the battery module with heating function in the present invention;

[0062] Figure 6 This is a cross-sectional view of the heating film and the movable end connection end plate in the specific embodiment 1 of the battery module with heating function of the present invention;

[0063] Figure 7 This is a structural diagram of the relative positions of the heating films in the specific embodiment 2 of the battery module with heating function of the present invention;

[0064] In the figure: 10-battery cell; 11-chamfer; 12-concave space; 20-end plate; 201-movable end connecting end plate; 202-fixed end connecting end plate; 21-clamping hole; 22-clamping buckle; 221-expansion sleeve; 222-fixing screw; 223-blocking cap; 30-heating film; 31-unloading hole; 32-unloading gap; 33-connection terminal; 341-positioning fixed end; 342-movable end; 35-long hole; 36-weak part. DETAILED DESCRIPTION

[0065] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. That is, the specific embodiments described herein are only some of the specific embodiments of the present invention, not all of the specific embodiments. Generally, the components of the specific embodiments of the present invention described and illustrated in the drawings herein can be arranged and designed in a variety of different configurations.

[0066] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but merely represents selected specific embodiments of the present invention. All other embodiments derived by those skilled in the art based on the specific embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0067] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0068] The features and performance of the battery box and battery module thereof in the present invention are further described in detail below in conjunction with specific embodiments.

[0069] Specific embodiment 1 of the battery module with heating function in the present invention: Figures 1 to 6As shown, the battery module mainly includes a battery cell 10, an end plate and a heating film 30. Among them, there are multiple battery cells 10, which are stacked along the thickness direction of the battery cell 10 to form a battery cell group. The battery cells 10 are relatively fixed to each other by gluing. The direction of battery cell stacking is the front-to-back direction. The front and rear ends of the heating film 30 are respectively a positioning fixed end 341 and a movable end 342. There are two end plates 20, namely a movable end connecting end plate 201 and a fixed end connecting end plate 202. The movable end connecting end plate 201 and the fixed end connecting end plate 202 are respectively arranged at the front and rear ends of the battery cell group.

[0070] In this embodiment, heating films 30 are bonded and fixed to the left and right sides of the battery pack. The heating films 30 can heat the battery cells when powered on, thereby increasing the working temperature of the battery cells 10. The heating films 30 are long and extend in the front-to-back direction. The heating films 30 include a film body and a heating wire fixed in the film body ( Figure 5 The middle dotted line indicates the heating wire routing area), the two terminal ends 33 of the heating wire are respectively located at the front and rear ends of the heating film. In this embodiment, the two heating films are connected in series through the two terminal ends of the movable end 342. In other embodiments, the heating films on the left and right sides can be provided as one piece, and in this case the heating film is U-shaped as a whole. In other embodiments, a plurality of heating wires can be provided on the heating film, for example, the number of heating wires corresponds to the number of battery cells. In this case, each heating wire has two terminal ends, and in this case, the two terminal ends of the heating wire are provided on the upper side, and the terminal ends of each heating wire are integrated together for easy installation.

[0071] During the charge and discharge process of the battery cell 10, the battery cell 10 expands and contracts, generating an alternating expansion force. In the stacking direction of the battery cell 10, the expansion forces of the battery cell 10 are superimposed on each other, and the heating film 30 is subjected to the pulling force of the battery cell 10 in the front and rear directions. The end of the heating film is prone to warping and deformation due to the uneven force, which aggravates the separation of the battery cell 10 from the positioning and fixing end 341 and the movable end 342. In order to improve the fixing effect of the heating film 30, a long hole 35 is provided at the movable end 342 in this embodiment. The long waist of the battery 35 extends in the front-to-back direction. The movable end connecting end plate 201 is provided with a latch hole 21 corresponding to the long hole 35. The movable end connecting end plate 201 is also provided with a columnar latch 22. The latch 22 passes through the long hole 35 and the latch hole 21 and is then latched onto the movable end connecting end plate 201. The latch 22 and the long hole 35 can slide together in the front-to-back direction of the fixed front edge, allowing the movable end 342 and the movable end connecting end plate 201 to move relative to each other in the front-to-back direction of the fixed front edge, facilitating installation. After the latch 22 is installed, the movable end 342 is pressed against the movable end connecting end plate 201. A certain pressure is exerted between the movable end and the movable end connecting end plate. However, after the battery cell expands, the movable end and the movable end connecting end plate are subjected to a force in the front-to-back direction. When this force is greater than the maximum static friction between the two, the movable end and the movable end connecting end plate can move relative to each other in the front-to-back direction.

[0072] In this embodiment, the buckle 22 includes an expansion sleeve 221 and a fixing screw 222. The expansion sleeve 221 is inserted into the clamping hole. After the fixing screw 222 is screwed into the expansion sleeve 221, the expansion sleeve 221 is clamped and fixed to the clamping hole. In this embodiment, a circular hole is provided on the positioning fixing end 341 of the heating film, and a circular hole is also provided on the fixed end connecting end plate 202. The positioning fixing plate of the heating film and the fixed end connecting end plate 202 are fixed together by the buckle. It is ensured that the front and rear ends of the heating film will not warp or deform. The circular holes on the fixed end connecting end plate and the heating film form positioning holes for positioning with the buckle, and the fixed end connecting end plate and the positioning fixing end are positioned by the buckle. In other embodiments, a positioning structure can be provided between the fixed end connecting end plate and the positioning fixing end, such as a positioning protrusion provided on the fixed end connecting end plate, and a positioning hole provided on the positioning fixing end. In other embodiments, a positioning pin can be provided to pass through the positioning fixing end and then be inserted into the end plate. The positioning pin has no stop cap, and a fixing bolt is provided to fix the heating film to the fixed end connecting end plate.

[0073] During use, the fixed end 341 of the heating film is first secured with a buckle, and then the movable end 342 is pressed against the buckle to prevent wrinkles in the middle of the heating film and facilitate installation. In other embodiments, the fixed end can also be secured with a fixing bolt, a dowel pin with a retaining cap, etc. In other embodiments, both ends of the heating film can be movable ends, or both ends can be fixed ends.

[0074] A stop cap 223 is provided at the end of the fixing screw 222. The stop cap 223 is provided at the end of the buckle 22 away from the end plate 20. The stop cap 223 faces the side of the heating film 30 and cooperates with the heating film 30 to stop and limit the movement of the heating film 30 in the direction away from the battery cell 10. Under the action of the stop cap 223, the heating film 30 is not easy to warp, and the bonding position between the heating film 30 and the battery cell 10 is not easy to debond, so that the fixing effect of the heating film 30 is better. Even if the heating film is debonded, the heating film does not warp, and it will not affect its contact area with the module, and the heating film can heat the battery cell normally. The buckle in this embodiment constitutes a connector connecting the front and rear ends of the heating film and the end plate, and the stop cap constitutes a stopping structure that limits the end of the heating film from moving in the direction away from the battery cell group.

[0075] An unloading hole 31 is provided on the heating film 30. The portion where the unloading hole 31 is located is formed in a weak portion 36 which is easily deformed after being subjected to external force. The unloading hole 31 is an oblong through hole. The waist of the unloading hole 31 extends in the up and down direction, that is, extends along the height direction of the battery cell 10.

[0076] In this embodiment, multiple weak portions 36 extend vertically, each with an unloading hole 31. These holes 31 are spaced apart along the length of the heating film 30. When the heating film 30 is subjected to alternating expansion forces along the front-to-back direction, it stretches in the front-to-back direction. This alternating expansion force is transmitted to the unloading holes 31, causing the unloading holes 30 to deform. The portions of the weak portion 36 on either side of the unloading hole move away from each other, allowing the heating film 30 to adapt to the deformation of the battery cell pack. In other embodiments, the number of unloading holes can be adjusted as needed, for example, providing two unloading holes in a single weak portion, one above the other.

[0077] In this embodiment, the unloading hole is an oblong hole. When the heating film is pulled and deformed, there are no sharp corners at both ends of the unloading hole, which can effectively prevent the heating film from being torn at the end of the unloading hole.

[0078] like Figure 1 and Figure 4 As shown, chamfers 11 are processed at the edges extending up and down the battery cell shell. When two battery cells 10 are stacked, the two chamfers 11 form a concave space 12. After the heating film 30 is bonded and fixed to the battery cell 10, no adhesive is applied to the concave space 12, and the weak portion 36 on the heating film 30 faces the concave space 12 in the left and right directions, so that there is a gap between the weak portion 36 of the heating film 30 and the stacking position of the battery cells 10.

[0079] The position of the unloading hole 31 is directly opposite to the stacking position of the two adjacent battery cells 10 in the battery cell group. The stacking position of the two battery cells 10 is the part where the two battery cells 10 are bonded to each other, so that the two adjacent battery cells 10 are respectively bonded and fixed to the parts of the heating film 30 on the left and right sides of the unloading hole 31. When the battery cells 10 expand during charging and discharging, the opposite sides of the two adjacent battery cells 10 bulge, and the distance between the adjacent battery cells 10 becomes larger. By setting the unloading hole 31 at the stacking position of the two battery cells 10, the weak part 36 of the heating film 30 is more easily deformed and can adapt to the change in the distance between the adjacent battery cells 10, thereby maintaining the bonding strength of the heating film 30 to the battery cells 10. In other embodiments, the unloading hole may not be directly opposite to the stacking position of the two battery cells 10. At the same time, there may be a gap between the weak part 36 of the heating film 30 and the stacking position of the battery cells 10, and there is no need to inject glue into the gap when assembling the battery module.

[0080] Each unloading hole 31 is located at the corresponding stacked position of adjacent battery cells 10. In adjacent weak portions 36 on the same heating film 30, the unloading holes 31 are arranged alternately in an upper and lower pattern in the front-to-back direction. Specifically, the unloading hole 31 in one weak portion 36 extends upward from the middle of the heating film 30 and is positioned higher, while the unloading hole 31 in another weak portion 36 extends downward from the middle of the heating film 30 and is positioned lower. When the heating film 30 is subjected to alternating expansion forces, the deformation of the upper portion of the heating film 30 is relatively balanced with the deformation of the lower portion of the heating film 30, preventing the heating film 30 from being stretched into a trapezoidal or inverted trapezoidal shape, which could cause stress concentration and fracture in the heating film 30.

[0081] In this embodiment, heating films 30 are bonded and fixed on both sides of the battery cell group. On the left heating film 30 and the right heating film 30, in the two weak parts 36 opposite to the stacking positions of the same pair of adjacent battery cells 10, the unloading hole 31 on one weak part 36 is arranged at the top, and the unloading hole 31 on the other weak part 36 is arranged at the bottom. In this embodiment, there are two distribution forms: one is that the unloading hole 31 on the left heating film 30 extends downward from the middle of the heating film 30, and the unloading hole 31 on the right heating film 30 extends upward from the middle of the heating film 30; the other is that the unloading hole on the left heating film 30 extends upward from the middle of the heating film 30, and the unloading hole on the right heating film 30 extends downward from the middle of the heating film 30.

[0082] Of course, the battery module in the present invention is not limited to the technical solution provided in the above-mentioned specific embodiment 1, and the technical solution provided in the following specific embodiments can also be adopted.

[0083] Specific embodiment 2 of the battery module with heating function in the present invention: The difference from the above specific embodiment is that the heating film in this embodiment is provided with an unloading slit replacing the unloading hole in specific embodiment 1, such as Figure 7 As shown, the heating film 30 is processed with an unloading slit 32 by mechanical punching. The unloading slit 32 extends in a direction perpendicular to the stacking of the battery cells. The heating film 30 is disconnected at the unloading slit 32. When the heating film 30 is stretched by the alternating expansion force, the opening at the unloading slit 32 is enlarged, causing the heating film 30 to have a greater degree of deformation. At the same time, circular holes are punched at both ends of the unloading slit 32. The edges of the circular holes have a smooth transition, which can prevent the heating film from tearing at this point. It should be noted that the unloading slit in this embodiment is only different in shape from the unloading hole in Specific Example 1. The position of the unloading slit is the same as that of the unloading hole.

[0084] Specific embodiment 3 of the battery module with heating function in the present invention: The structure of the battery module in this embodiment is different from that of the above-mentioned specific embodiments only in that: in this embodiment, a long hole extending forward and backward is also provided on the movable end connecting end plate.

[0085] Specific embodiment 4 of the present invention's battery module with heating function: The structure of the battery module in this embodiment differs from the above-mentioned specific embodiments only in that the connecting member is a fixing bolt, which is threadedly fixed to the end plate, and the bolt head of the fixing bolt restricts the movement of the end of the heating membrane away from the battery cell. In other embodiments, the connecting member can also be a pin fixed to the end plate, with a stop cap provided at one end of the pin to prevent separation from the pin.

[0086] Specific embodiment 5 of the battery module with heating function of the present invention differs from the above-mentioned specific embodiments in that the structure of the battery module in this embodiment is only different in that the end plate is provided with a long groove extending forward and backward, and the connecting member slides into the long groove. In other embodiments, a fixed plate can also be provided at the movable end, and a long groove extending forward and backward is provided on the fixed plate, so that the clip can slide within the long groove, thereby ensuring that the movable end and the end plate can move relative to each other in the forward and backward directions.

[0087] Specific embodiment 6 of the battery module with heating function in the present invention, the structure of the battery module in this embodiment is different from the above specific embodiments only in that: the connecting part in this embodiment is a connecting stud welded and fixed to the end plate, and a nut is provided on the connecting stud after the movable end is fixed, and the nut constitutes a stopping structure, which limits the movable end from moving away from the battery cell group through the nut.

[0088] Specific embodiment 7 of the battery module with heating function in the present invention: The structure of the battery module in this embodiment is different from that of the above-mentioned specific embodiments only in that: in this embodiment, an unloading groove is provided at the position of the unloading hole in specific embodiment 1 to replace the unloading hole. The unloading groove serves as a thinning depression that can reduce the film thickness. It is concave from the outer side surface of the heating film away from the battery cell to the inner side surface of the heating film close to the battery cell. Although the unloading groove is not arranged through in the thickness direction of the heating film, the film thickness at the position where the unloading groove is located in the heating film is smaller than the film thickness at other parts, so that the heating film is more easily stretched and deformed here, thereby providing the deformation ability of the heating film without changing the material of the heating film.

[0089] Specific embodiment 8 of the battery module with heating function in the present invention: The structure of the battery module in this embodiment is different from that of the above-mentioned specific embodiments only in that: in this embodiment, the unloading holes are on the heating film and arranged at intervals along the arrangement direction of the battery cells, and all the unloading holes on the same heating film are at the same height.

[0090] Specific embodiment 9 of the battery module with heating function in the present invention: The structure of the battery module in this embodiment is different from that of the above specific embodiments only in that: in this embodiment, the unloading holes on the left and right sides of the battery cell are also at the same height direction.

[0091] Specific embodiment 10 of the battery module with heating function in the present invention: The structure of the battery module in this embodiment is different from the above-mentioned specific embodiments only in that: the unloading hole in this embodiment is in the shape of a square hole, and the hole edge of the square hole has sharp corners. When the heating film is stretched by the alternating expansion force, it may tear at the sharp corners, thereby lengthening the heating film and being able to adapt to the battery cell group that has become longer due to thermal expansion.

[0092] Specific embodiment 11 of the battery module with heating function in the present invention: The structure of the battery module in this embodiment is different from the above-mentioned specific embodiments only in that: in this embodiment, multiple weak parts are arranged on the heating film along the length direction, wherein two adjacent weak parts form a pair, and the unloading holes in this pair of weak parts are all arranged upward, and the unloading holes in another pair of weak parts adjacent to the pair of weak parts are all arranged downward. At this time, it is satisfied that on the heating film arranged on the side of the battery cell, there is at least a pair of weak parts adjacent in the arrangement direction of the battery cells that meet the following requirements: the hole or slit or thinning depression on one weak part is arranged upward, and the hole or slit or thinning depression on the other weak part is arranged downward.

[0093] Specific embodiment 12 of the present invention's battery module with a heating function: The structure of the battery module in this embodiment differs from the above-mentioned specific embodiments only in that: in this embodiment, both the front and rear ends of the heating membrane are movable ends. The movable end and the plate connecting the movable ends are provided with elongated holes that slide with the connector in the front-to-back direction, allowing the movable end and the plate connecting the movable ends to move relative to each other in the front-to-back direction. In other embodiments, the movable end and the plate connecting the movable ends are provided with elongated slots that slide with the connector in the front-to-back direction. In this case, a fixed plate is added to the movable end, and the slot is disposed on the fixed plate.

[0094] A specific embodiment of the battery box in the present invention: the battery box includes a box body, and at least two battery modules are arranged in the box body. The structure of the battery module is the same as the battery module in the above-mentioned specific embodiment of the battery module. Therefore, the specific embodiment of the battery box in the present invention will not be repeated.

[0095] The specific implementation methods described above further illustrate the invention objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A battery module with heating function, comprising: A plurality of battery cells are provided, and the plurality of battery cells are stacked in a front-to-back direction to form a battery cell group; End plates, arranged at the front and rear ends of the battery cell group; A heating film extending in the front-to-back direction and arranged on at least one of the left side and the right side of the battery cell group for heating the battery cells; The heating film is bonded and fixed to the battery cell; It is characterized by: The connecting piece, the heating film ends at the front and rear ends of the heating film are connected to the end plates at both ends through the connecting piece, the connecting piece has a stopping structure for limiting the movement of the heating film ends in the direction away from the battery cell group, the connecting piece is stuck on the corresponding end plate, the stopping structure on the connecting piece is a stop cap on the side of the heating film facing away from the battery cell, at least one of the front and rear ends of the heating film is a movable end, and the end plate connected to the movable end is a movable end connecting end plate; the movable end and / or the movable end connecting end plate is provided with a long hole or a long groove that slides with the connecting piece in the front and rear direction, so that the movable end and the movable end connecting end plate can move relative to each other in the front and rear direction; a weak part is provided on the heating film, and the weak part is provided with a hole or a slit that passes through both sides of the heating film; or a thinning depression for reducing the thickness of the film is provided on the weak part.

2. The battery module with heating function according to claim 1, characterized in that: The connecting piece connected to the movable end connecting end plate is used to press the movable end onto the movable end connecting end plate. The movable end and the movable end connecting end plate move relative to each other in the front-to-back direction when the module expansion force driven to move relative to each other in the front-to-back direction is greater than the maximum static friction force between the two.

3. The battery module with heating function according to claim 2, characterized in that: The movable end is provided with the long hole.

4. The battery module with heating function according to claim 2, characterized in that: One end of the heating film is a positioning fixed end, and the end plate connected to the positioning fixed end is a fixed end connecting end plate. The positioning fixed end is fixed to the fixed end connecting end plate through a connecting piece. A positioning structure is provided between the fixed end connecting end plate and the positioning fixed end, or the fixed end connecting end plate and the positioning fixed end are positioned through a connecting piece.

5. The battery module with heating function according to claim 1 or 2, characterized in that: The weak portion extends perpendicular to the arrangement direction of the battery cells and is opposite to the stacking positions of two adjacent battery cells.

6. The battery module with heating function according to claim 5, characterized in that: Two adjacent weak parts in the direction of cell arrangement both meet the following requirements: the hole, slit or thinning depression on one weak part is arranged upward, and the hole, slit or thinning depression on the other weak part is arranged downward.

7. The battery module with heating function according to claim 5, characterized in that: Heating films are provided on the left and right sides of the battery cell group. Of the two weak parts on the left and right heating films that are opposite to the stacking positions of the same pair of adjacent battery cells, the hole, slit or thinning depression on one is set higher, and the hole, slit or thinning depression on the other is set lower.

8. The battery module with heating function according to claim 5, characterized in that: There is a gap between the weak portion on the heating film and the stacking position of the adjacent battery cells, and the hole or slit on the weak portion communicates with the gap.

9. Battery box, including: Box; A battery module is installed in a box, characterized in that the battery module is the battery module according to any one of claims 1 to 8.

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