Battery box and its battery module

Abstract

The present invention relates to a battery box and a battery module thereof. The battery module includes battery cells stacked in the front-rear direction; end plates arranged at the front and rear ends of the battery cell group; a heating film arranged on at least one of the left and right side surfaces of the battery cell group for heating the battery cells. The heating film is provided with a weak part, and the weak part is provided with holes or slits penetrating both sides of the heating film; or the weak part is provided with a thinning depression for thinning the film thickness. The weak part extends along a direction perpendicular to the arrangement direction of the battery cells and is opposite to the stacking positions of two adjacent battery cells. The weak part on the heating film is more likely to deform, so that when the heating film is subjected to an external force, the parts on both sides of the weak part in the heating film will move away from each other, and the influence of the alternating expansion force on the heating film is weakened by the stretching deformation of the weak part, making the heating film more likely to deform when subjected to an external force. Without replacing the heating film material, the deformation ability of the heating film can be improved, and the production cost can be reduced.

Description

Technical Field

[0001] The present invention relates to a battery box and a battery module thereof. Background Art

[0002] Existing new energy vehicles use the battery box installed on the vehicle as the energy source. The battery cells in the battery box discharge to drive the motor of the new energy vehicle to operate. However, the existing battery box is affected by the ambient temperature during use. Taking lithium-ion batteries as an example, at low temperatures, the battery discharge capacity is extremely poor. Even when fully charged, the driving ability of the vehicle will be greatly reduced. In addition, charging at low temperatures greatly affects the service life of power batteries because at low temperatures, the conduction ability of charged ions inside the battery is poor, and the transfer and embedding ability of charges inside the negative electrode material structure are also poor. If charging is carried out with normal current at low temperatures, a large number of lithium ions will accumulate on the surface of the negative electrode and cannot be embedded, and electrons will deposit on the electrode surface to form a lithium metal accumulation; and lithium metal is very prone to the phenomenon of uneven crystal growth. When the dendrites grow to a sufficient scale, they may pierce the separator, causing a direct connection between the positive and negative electrodes and forming an internal short circuit in the battery cell.

[0003] To solve the problem that the battery box is affected by the external ambient temperature and affects its operation, technicians have proposed to add a heating film in the battery module in the battery box that can provide heat to the battery cells. The heating film is fixed on the side of the battery cell by an adhesive method. When powered on, it generates heat by itself and can transfer the heat to the battery cell to increase the working temperature of the battery cell. However, when the battery cell itself charges and discharges, corresponding thermal expansion will occur, and the heating film adhered to the module will be subjected to alternating pulling by the expansion force of the module. As a result, the heating film will be stretched when subjected to alternating pulling. When the alternating pulling force is greater than the bearing limit of the heating film, the heating film will be broken, resulting in potential safety hazards. At present, to solve the problem that the heating film is easily damaged under the action of alternating pulling force, technicians will use materials with high strength and high elastic deformation ability to make the heating film, but this method will increase the production cost of the battery box and the battery module. Summary of the Invention

[0004] The purpose of the present invention is to provide a battery module to solve the problem of high production cost caused by using a heating film with high strength to ensure its elastic deformation ability in the existing battery module;

[0005] Another purpose of the present invention is to provide a battery box using this battery module, which has the advantage of low production cost.

[0006] To achieve the above purpose, the battery module in the present invention adopts the following technical solutions:

[0007] The battery module includes:

[0008] Battery cells, a plurality of which are provided. The plurality of battery cells are stacked in the front-rear direction to form a battery cell group;

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

[0010] A heating film is arranged on at least one of the left and right sides of the battery cell group for heating the battery cells;

[0011] Weak parts extending vertically are provided on the heating film, and holes or slits penetrating both sides of the heating film are provided on the weak parts; or a thinning depression for thinning the film thickness is provided on the weak parts;

[0012] The weak parts extend in a direction perpendicular to the arrangement direction of the battery cells and are opposite to the stacking positions of two adjacent battery cells.

[0013] The beneficial effects are as follows: When the battery cells are charged and discharged, two adjacent battery cells expand in a direction away from each other. Since the side surfaces of the battery cells are relatively fixed to the heating film, when the alternating expansion force is transmitted to the weak parts, because the openings formed by the holes or slits in the heating film can become larger and the thinning depressions make the film thickness thinner and thus more easily deformed, when the heating film is subjected to an external force, the parts on both sides of the weak part in the heating film will move away from each other, and the alternating expansion force's influence on the heating film is weakened through the stretching deformation of the weak parts, making the heating film more easily deformed when subjected to an external force. Without changing the heating film material, the deformation ability of the heating film can be improved and the production cost can be reduced.

[0014] Furthermore, at least one pair of weak parts adjacent in the battery cell arrangement direction satisfy that: the holes or slits or thinning depressions on one weak part are arranged upward, and the holes or slits or thinning depressions on the other weak part are arranged downward.

[0015] The beneficial effects are as follows: When the adjacent weak parts satisfy that the holes or slits or thinning depressions on one weak part are arranged upward and the holes or slits or thinning depressions on the other weak part are arranged downward, when the heating film is affected by the alternating expansion force, the deformation amount of the upper part of the heating film is relatively balanced with the deformation amount of the lower part of the heating film, avoiding situations such as the heating film being stretched into a trapezoidal or inverted trapezoidal shape, and stress concentration occurring in the heating film resulting in accidental fracture of the heating film, and improving the strength of the heating film to resist the alternating expansion force.

[0016] Furthermore, both of the two weak parts adjacent in the battery cell arrangement direction satisfy that: the holes or slits or thinning depressions on one weak part are arranged upward, and the holes or slits or thinning depressions on the other weak part are arranged downward.

[0017] Its beneficial effects are as follows: For adjacent weak parts, the holes, slits or thinning depressions on one weak part are arranged upwards, and the holes, slits or thinning depressions on the other weak part are arranged downwards. When the heating film is affected by the alternating expansion force, the deformation amount of the upper part of the heating film is relatively balanced with the deformation amount of the lower part of the heating film, avoiding the heating film being stretched into a trapezoidal or inverted trapezoidal shape, etc., and avoiding stress concentration in the heating film resulting in accidental fracture of the heating film, thus improving the strength of the heating film to resist the alternating expansion force.

[0018] Further, heating films are provided on both the left side and the right side of the battery cell group. Among the two weak parts on the left heating film and the right heating film that are opposite to the stacking positions of the same pair of adjacent battery cells, the holes, slits or thinning depressions on one are arranged upwards, and the holes, slits or thinning depressions on the other are arranged downwards.

[0019] Its beneficial effects are as follows: Such an arrangement can stagger the positions where the heating films on the left and right sides of the battery cell are deformed by the alternating expansion force in the up and down directions, avoiding the situation where one end of the battery cell is tight and the other end is loose in the up and down directions, and enabling the heating film to withstand a higher alternating expansion force.

[0020] Further, the heating film is adhesively fixed to the battery cell.

[0021] Its beneficial effects are as follows: The heating film is adhesively fixed to the battery cell, without the need for other auxiliary connecting structural parts, which can reduce production costs. At the same time, the two are fixed by adhesion, with high operation efficiency, saving time and effort.

[0022] Further, there is a gap between the weak part on the heating film and the stacking position of the adjacent battery cell, and the holes or slits on the weak part communicate with the gap.

[0023] Its beneficial effects are as follows: There is a gap between the weak part on the heating film and the stacking position of the adjacent battery cell. Here, there is no need to specially inject adhesive separately, and the adhesive fixation of the heating film and the battery cell can be completed by mechanical gluing, thereby improving the assembly efficiency.

[0024] Further, the adjacent battery cells are adhesively fixed to each other.

[0025] Its beneficial effects are as follows: The battery cells are adhesively fixed to each other, without the need for other auxiliary connecting structural parts, which can reduce production costs. At the same time, the battery cells are fixed by adhesion, with high operation efficiency, saving time and effort.

[0026] Further, at least one end of the slit or hole in the weak part has a circular arc edge in the direction perpendicular to the arrangement direction of the battery cells to prevent the heating film from tearing at this end.

[0027] The beneficial effects are as follows: An arc edge with an arc transition is provided in the hole or slit. When the heating film is pulled and deformed, there are no sharp corners at the arc transition section, which can effectively prevent the heating film from being torn at the position corresponding to the hole or slit, and improve the ability of the heating film to resist alternating expansion forces.

[0028] Furthermore, the heating film is adhesively fixed to the battery cell group. At least one of the front and rear ends of the heating film is a movable end. The front and rear ends of the heating film are respectively connected to the end plates at both ends through connecting members. The connecting members have a stop structure that restricts the movement of the end of the heating film away from the battery cell group. The end plate connected to the movable end is the movable end connecting end plate;

[0029] Long holes or long grooves that are slidably matched with the connecting members in the front-rear direction are provided on the movable end and / or the movable end connecting end plate, so that the movable end and the movable end connecting end plate can move relative to each other in the front-rear direction.

[0030] Beneficial effects: The front and rear ends of the heating film are respectively connected to the end plates at both ends through connecting members. The stop structure on the connecting members can prevent the movable end from warping, improve the fixing effect of the heating film. The stop structure can be in stop cooperation with the movable end, so that the end of the heating film does not warp. At the same time, the long holes on the movable end or the baffle enable the movable end and the end plate to move relative to each other, which is convenient for installation and can adapt to the movement of the movable end connecting end plate when the battery cells expand.

[0031] To achieve the above object, the following technical solution is adopted for the battery box in the present invention:

[0032] A battery box, comprising:

[0033] A box body;

[0034] A battery module, installed in the box body. The battery module includes:

[0035] Battery cells, a plurality of which are provided. The plurality of battery cells are stacked in the front-rear direction to form a battery cell group;

[0036] End plates, arranged at the front and rear ends of the battery cell group;

[0037] A heating film, arranged on at least one of the left side surface and the right side surface of the battery cell group for heating the battery cells;

[0038] Weak parts extending vertically are provided on the heating film. Holes or slits penetrating both sides of the heating film are provided on the weak parts; or thinning depressions for thinning the film thickness are provided on the weak parts;

[0039] The weak parts extend in a direction perpendicular to the arrangement direction of the battery cells and are opposite to the stacking positions of two adjacent battery cells.

[0040] Its beneficial effects are as follows: When the battery cells are charged and discharged, two adjacent battery cells expand in a direction away from each other. Since the side surface of the battery cell is relatively fixed to the heating film, when the alternating expansion force is transmitted to the weak part, the opening formed by the hole or slit in the heating film can become larger, and the thinning and depression make the film thickness thinner and easier to deform. Therefore, when an external force acts on the heating film, the parts on both sides of the weak part in the heating film move away from each other, and the alternating expansion force's influence on the heating film is weakened through the stretching deformation of the weak part, making the heating film easier to deform when subjected to an external force. Without replacing the heating film material, the deformation ability of the heating film can be improved, and the production cost can be reduced.

[0041] Further, at least one pair of weak parts adjacent in the battery cell arrangement direction satisfy that the hole or slit or thinning depression on one weak part is arranged higher, and the hole or slit or thinning depression on the other weak part is arranged lower.

[0042] Its beneficial effects are as follows: The adjacent weak parts satisfy that the hole or slit or thinning depression on one weak part is arranged higher, and the hole or slit or thinning depression on the other weak part is arranged lower. When the heating film is affected by the alternating expansion force, the deformation amount of the upper part of the heating film is relatively balanced with the deformation amount of the lower part of the heating film, avoiding the heating film being stretched into a trapezoidal or inverted trapezoidal shape, etc., and the occurrence of stress concentration in the heating film resulting in accidental fracture of the heating film, and improving the strength of the heating film to resist the alternating expansion force.

[0043] Further, both of the two weak parts adjacent in the battery cell arrangement direction satisfy that the hole or slit or thinning depression on one weak part is arranged higher, and the hole or slit or thinning depression on the other weak part is arranged lower.

[0044] Its beneficial effects are as follows: The adjacent weak parts satisfy that the hole or slit or thinning depression on one weak part is arranged higher, and the hole or slit or thinning depression on the other weak part is arranged lower. When the heating film is affected by the alternating expansion force, the deformation amount of the upper part of the heating film is relatively balanced with the deformation amount of the lower part of the heating film, avoiding the heating film being stretched into a trapezoidal or inverted trapezoidal shape, etc., and the occurrence of stress concentration in the heating film resulting in accidental fracture of the heating film, and improving the strength of the heating film to resist the alternating expansion force.

[0045] Further, heating films are arranged on both the left side surface and the right side surface of the battery cell group. Among the two weak parts on the left heating film and the right heating film 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 higher, and the hole or slit or thinning depression on the other is arranged lower.

[0046] The beneficial effects are as follows: Such an arrangement can cause 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 deformed by the alternating expansion force to be staggered in the up and down direction, avoiding the situation where one end of the battery cell is tightened and the other end is relaxed in the up and down direction, and enabling the heating film to withstand a higher alternating expansion force.

[0047] Furthermore, the heating film is adhesively fixed to the battery cell.

[0048] The beneficial effects are as follows: The heating film is adhesively fixed to the battery cell, without the need for other auxiliary connecting structural parts, which can reduce the production cost. At the same time, the two are fixed by adhesion, with high operation efficiency, saving time and effort.

[0049] Furthermore, there is a gap between the weak part on the heating film and the stacking position of the adjacent battery cells, and the holes or slits on the weak part communicate with the gap.

[0050] The beneficial effects are as follows: There is a gap between the weak part on the heating film and the stacking position of the adjacent battery cells. Here, there is no need to specially inject adhesive separately, and the mechanical gluing method can be used to complete the adhesive fixation of the heating film and the battery cell, thereby improving the assembly efficiency.

[0051] Furthermore, the adjacent battery cells are adhesively fixed to each other.

[0052] The beneficial effects are as follows: The battery cells are adhesively fixed to each other, without the need for other auxiliary connecting structural parts, which can reduce the production cost. At the same time, the battery cells are fixed by adhesion, with high operation efficiency, saving time and effort.

[0053] Furthermore, at least one end of the slit or hole in the weak part has a circular arc edge perpendicular to the arrangement direction of the battery cells to prevent the heating film from tearing at this end.

[0054] The beneficial effects are as follows: A circular arc edge with a circular arc transition is provided in the hole or slit. When the heating film is pulled and deformed, there are no sharp corners at the circular arc transition section, which can effectively prevent the heating film from tearing at the position corresponding to the hole or slit, and improve the ability of the heating film to resist the alternating expansion force.

[0055] Furthermore, the heating film is adhesively fixed to the battery cell group. At least one end of the front and rear ends of the heating film is a movable end. The front and rear ends of the heating film are respectively connected to the end plates at both ends through connecting pieces. The connecting pieces have a stop structure that restricts the movement of the end of the heating film away from the battery cell group. The end plate connected to the movable end is the movable end connection end plate;

[0056] Long holes or long grooves that are slidably matched with the connecting pieces in the front and rear directions are provided on the movable end and / or the movable end connection end plate, so that the movable end and the movable end connection end plate can move relative to each other in the front and rear directions.

[0057] Beneficial effects: The front and rear ends of the heating film are respectively connected to the end plates at both ends through connectors. The stop structure on the connectors can prevent the movable end from warping, improving the fixing effect of the heating film. The stop structure can cooperate with the movable end to prevent the end of the heating film from warping. At the same time, the long holes on the movable end or the baffle enable the movable end and the end plate to move relative to each other, facilitating installation and accommodating the movement of the movable end connecting the end plate when the battery cell expands. Description of the Drawings

[0058] Figure 1 It is a schematic structural diagram of the specific embodiment 1 of the battery module in the present invention;

[0059] Figure 2 It is a schematic installation structure diagram of the movable end connecting the end plate and the heating film in the specific embodiment 1 of the battery module in the present invention;

[0060] Figure 3 It is a schematic structural diagram of the relative position of the heating film in the specific embodiment 1 of the battery module in the present invention;

[0061] Figure 4 It is a schematic structural diagram of the heating film of the battery module in the specific embodiment 1 of the present invention at the battery cell stacking position;

[0062] Figure 5 It is a schematic structural diagram of the heating film in the specific embodiment 1 of the battery module in the present invention;

[0063] Figure 6 It is a cross-sectional view of the heating film and the movable end connecting the end plate in the specific embodiment 1 of the battery module in the present invention;

[0064] Figure 7 It is a schematic structural diagram of the relative position of the heating film in the specific embodiment 2 of the battery module in the present invention;

[0065] 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 - card hole; 22 - buckle; 221 - expansion sleeve; 222 - fixing screw; 223 - retaining cap; 30 - heating film; 31 - unloading hole; 32 - unloading slot; 33 - wiring terminal; 341 - positioning fixed end; 342 - movable end; 35 - long hole; 36 - weak part. Detailed Embodiments

[0066] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein can be arranged and designed in various different configurations.

[0067] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0068] It should be noted that relational terms such as "first" and "second" are only used 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 "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0069] The features and performance of the battery box and its battery module in the present invention will be further described in detail below with reference to embodiments.

[0070] Embodiment 1 of the battery module in the present invention: As Figures 1 to 6 shown, the battery module mainly includes battery cells 10, end plates, and a heating film 30. Among them, there are multiple battery cells 10, which are stacked along the thickness direction of the battery cells 10 to form a battery cell group, and the battery cells 10 are relatively fixed to each other by gluing. The stacking direction of the battery cells is the front-rear direction, and the front and rear ends of the heating film 30 are a positioning fixed end 341 and a movable end 342 respectively. There are two end plates 20, namely a movable end connection end plate 201 and a fixed end connection end plate 202, and the movable end connection end plate 201 and the fixed end connection end plate 202 are respectively arranged at the front end and the rear end of the battery cell group.

[0071] In this embodiment, there are two heating films 30 corresponding to one battery cell group, which are fixed to the left and right sides of the battery cell 10 by an adhesive with a thickness of 0.1 mm in a gluing manner. When the heating film 30 is powered on, heat will be transferred to the battery cell 10 to increase the working environment temperature of the battery cell 10.

[0072] In this embodiment, heating films 30 are adhesively fixed to both the left and right sides of the battery cell group. The heating film 30 is strip-shaped and extends in the front-rear direction. The heating film 30 includes a film body and heating wires fixed in the film body ( Figure 5 the dotted lines in indicate the heating wire routing areas). The two wiring ends 33 of the heating wire are respectively at the front and rear ends of the heating film. In this embodiment, the two heating films are connected in series through the two wiring terminals of the movable end 342. In other embodiments, the heating films on the left and right sides can be integrally provided, and at this time, the heating film is integrally U-shaped. In other embodiments, multiple heating wires can be provided on the heating film. For example, the number of heating wires corresponds one-to-one to the number of battery cells. At this time, each heating wire has two wiring ends, and the two wiring ends of the heating wire are provided on the upper side, and the wiring ends of each heating wire are integrated together for easy installation.

[0073] The heating film 30 is strip-shaped. Because the battery cell 10 will generate alternating expansion forces during the charge and discharge process, the alternating expansion forces will pull the heating film 30 in the arrangement direction of the battery cells, that is, the front-rear direction. Therefore, in the heating film 30 of the present invention, a weak part that is easily deformed when subjected to an external force is provided, and a relief hole 31 is provided on the weak part. The relief hole 31 penetrates in the thickness direction of the heating film 30. The shape of the relief hole 31 is an oblong hole, and the waist of the relief hole 31 extends along the direction perpendicular to the arrangement of the battery cells 10, that is, the height direction of the battery cell 10 in the figure.

[0074] In this embodiment, a plurality of weak parts are provided along the length direction of the heating film 30, and only one relief hole 31 is provided in each weak part. The relief holes 31 are spaced apart in the length direction of the heating film 30. When the heating film 30 is affected by the alternating expansion force in the front-rear direction, the heating film 30 will be stretched in the front-rear direction accordingly. At this time, when the alternating expansion force is transmitted to the relief hole 31, the relief hole 30 deforms, and the parts on both sides of the relief hole on the weak part 36 move away from each other, so that the heating film 30 can adapt to the deformation of the battery cell group. In other embodiments, the number of relief holes can be set as needed. For example, two relief holes are provided in one weak part, and the two relief holes are arranged one above the other.

[0075] Because the shape of the relief hole 31 is an oblong hole, both ends of the relief hole 31 have arc transition sections. When the heating film 30 is pulled and deformed, there are no sharp corners at the arc transition sections at both ends of the relief hole 31, which can effectively prevent the heating film 30 from being torn at the end of the relief hole 31.

[0076] Such as Figure 1 andFigure 4 As shown, chamfers 11 are machined at the edges of the battery cell housing that extend up and down. When two battery cells 10 are stacked, an inner concave space 12 is formed by enclosing the two chamfers 11. After the heating film 30 is bonded and fixed to the battery cell 10, no adhesive is applied in the inner concave space 12, and the weak part 36 on the heating film 30 faces the inner concave space 12 in the left - right direction, so that there is a gap between the weak part 36 of the heating film 30 and the stacking position of the battery cells 10.

[0077] The position where the unloading hole 31 is located is opposite to the stacking position of 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 adhesively bonded to each other, so that the two adjacent battery cells 10 are respectively adhesively fixed to the parts on the left and right sides of the unloading hole 31 on the heating film 30. When the battery cells 10 expand during charging and discharging, the opposite sides of the two adjacent battery cells 10 bulge, and the gap between the adjacent battery cells 10 becomes larger. By arranging 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 likely to deform, and can adapt to the change in the distance between the adjacent battery cells 10, so as to maintain the adhesive fixing strength between the heating film 30 and the battery cells 10.

[0078] At the same time, the weak part 36 of the heating film 30 faces the stacking position of the battery cells 10 and there is a gap between them, so there is no need to inject glue into the gap during the assembly of the battery module. In other embodiments, adhesive can also be injected into the inner concave space.

[0079] Each unloading hole 31 is arranged at the stacking position of the corresponding adjacent battery cells 10. Among the adjacent weak parts 36 on the same heating film 30, the unloading holes 31 are alternately arranged in an up - and - down manner in the front - back direction, that is, the unloading hole 31 in one weak part 36 extends upward from the middle of the heating film 30 and is arranged closer to the upper part, and the unloading hole 31 in one weak part 36 extends downward from the middle of the heating film 30 and is arranged closer to the lower part. When the heating film 30 is affected by the alternating expansion force, the deformation amount of the upper part of the heating film 30 is relatively balanced with the deformation amount of the lower part of the heating film 30, avoiding the heating film 30 being stretched into a trapezoidal or inverted trapezoidal shape, etc., and preventing stress concentration and fracture in the heating film 30.

[0080] In the present 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 corresponding to the stacking positions of the same pair of adjacent battery cells 10, the unloading hole 31 on one weak part 36 is arranged upward, and the unloading hole 31 on the other weak part 36 is arranged downward. In the present embodiment, there are two distribution forms: one is that the unloading holes 31 on the left heating film 30 extend downward from the middle of the heating film 30, and the unloading holes 31 on the right heating film 30 extend upward from the middle of the heating film 30; the other is that the unloading holes on the left heating film 30 extend upward from the middle of the heating film 30, and the unloading holes on the right heating film 30 extend downward from the middle of the heating film 30.

[0081] During the charging and discharging process of the battery cell, 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-to-back direction. 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 35 extends in the front-to-back direction, and a clamping hole 21 corresponding to the long hole 35 is provided on the movable end connecting end plate 201. The movable end connecting end plate 201 is also provided with a columnar clamping buckle 22. The clamping buckle 22 passes through the long hole 35 and the clamping hole 21 and is clamped on the movable end connecting end plate 201. The clamping buckle 22 and the long hole 35 can slide and cooperate in the front-to-back direction of the fixed front edge, so that the movable end 342 and the movable end connecting end plate 201 can move relative to each other in the front-to-back direction of the fixed front edge, so as to facilitate installation. After the clamping buckle 22 is installed, the movable end 342 is pressed on the movable end connecting end plate 201, and there is a certain pressure 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 the force is greater than the maximum static friction force 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.

[0082] 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 with the clamping hole. In this embodiment, a circular hole is set at the positioning and fixing end 341 of the heating film, and a circular hole is also set on the fixed end connecting end plate 202. The positioning and 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 be warped and deformed. The circular holes on the fixed end connecting end plate and the heating film form positioning holes for positioning with the buckle.

[0083] During use, first fix the positioning and fixing end 341 of the heating film through a buckle, and then press the movable end 342 through the buckle to avoid wrinkles in the middle of the heating film and facilitate the installation of the heating film. In other embodiments, the positioning and fixing end can also be fixed by fixing bolts, positioning pins with retaining caps, etc. In other embodiments, both ends of the heating film can be movable ends, or both ends can be fixed ends.

[0084] A retaining cap 223 is provided at the end of the fixing screw 222. The retaining cap 223 is provided at one end of the buckle 22 away from the end plate 20. The side of the retaining cap 223 facing the heating film 30 is in stop cooperation with the heating film 30, restricting the heating film 30 from moving away from the battery cell 10. Under the action of the retaining cap 223, the heating film 30 is not easily warped, and the bonding position between the heating film 30 and the battery cell 10 is not easily delaminated, making the fixing effect of the heating film 30 better. Even if the heating film is delaminated, as long as the heating film is not warped, it will not affect its contact area with the module, and the heating film can normally heat the battery cell. In this embodiment, the buckle constitutes a connecting member connecting the front and rear ends of the heating film to the end plate, and the retaining cap constitutes a stop structure restricting the end of the heating film from moving away from the battery cell group.

[0085] Of course, the battery module in the present invention is not limited to the technical solution provided in the above Embodiment 1, and the technical solution provided in the following embodiment can also be adopted.

[0086] Embodiment 2 of the battery module in the present invention: The difference from the above embodiment is that in this embodiment, an unloading slit is provided on the heating film to replace the unloading hole in Embodiment 1. As Figure 7 shown, an unloading slit 32 is machined on the heating film 30 by mechanical punching. The unloading slit 32 extends along the 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 an alternating expansion force, the opening at the unloading slit 32 is enlarged, enabling the heating film 30 to have a greater degree of deformation. At the same time, round holes are punched at both ends of the unloading slit 32, and the edges of the round holes are smoothly transitioned to prevent the heating film from tearing at this location. It should be noted that in this embodiment, only the shape of the unloading slit is different from that of the unloading hole in Embodiment 1, and the position of the unloading slit is the same as that of the unloading hole.

[0087] Embodiment 3 of the battery module in the present invention: The difference from the above embodiment is that in this embodiment, an unloading groove is provided at the position of the unloading hole in Embodiment 1 to replace the unloading hole. The unloading groove is a thinning depression capable of reducing the film thickness, which is recessed from the outer side of the heating film facing away from the battery cell to the inner side of the heating film close to the battery cell. Although the unloading groove is not provided through in the thickness direction of the heating film, the film thickness at the position of the unloading groove in the heating film is smaller than that of other parts, making the heating film more easily stretch-deformed at this location and providing the deformation ability of the heating film without changing the material of the heating film.

[0088] Embodiment 4 of the battery module in the present invention: The difference from the above embodiment is that in this embodiment, the unloading holes are on the heating film and are arranged at intervals along the arrangement direction of the battery cells. All the unloading holes on the same heating film are at the same height, and it is not limited to the scheme of arranging the unloading holes alternately up and down.

[0089] Embodiment 5 of the battery module in the present invention: The difference from the above embodiment is that in this embodiment, the unloading holes on the left and right sides of the battery cells are also in the same height direction, and it is not limited to the arrangement method of one up and one down.

[0090] Embodiment 6 of the battery module in the present invention: The difference from the above embodiment is that in this embodiment, the shape of the unloading hole is a square hole, and the edge of the square hole has sharp corners. When the heating film is stretched by the alternating expansion force, it may be torn at the sharp corners, so that the length of the heating film becomes longer, and it can adapt to the battery cell group that becomes longer due to thermal expansion.

[0091] Embodiment 7 of the battery module in the present invention: The difference from the above embodiment is that in this embodiment, a plurality of weak parts are arranged on the heating film along the length direction. Among them, two adjacent weak parts are a pair, and the unloading holes in this pair of weak parts are all arranged upward. In another pair of weak parts adjacent to this pair of weak parts, the unloading holes are all arranged downward. At this time, at least one pair of weak parts adjacent in the arrangement direction of the battery cells satisfies: 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. It is not limited to that in the two weak parts 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.

[0092] Embodiment 8 of the battery module in the present invention: The difference from the above embodiment is that in this embodiment, the connecting piece is a connecting stud welded and fixed to the end plate. After the movable end is fixed, a nut is arranged on the connecting stud, and the nut constitutes a stop structure to limit the movable end from moving away from the battery cell group in the direction away from the battery cell group. In other embodiments, the connecting piece can be a fixing bolt, and the fixing bolt is threadedly fixed on the end plate, and the bolt head of the fixing bolt restricts the end of the heating film from moving away from the battery cells. In other embodiments, the connecting piece can also be a pin fixed on the end plate, and a retaining cap is arranged at one end of the pin to limit the separation from the pin.

[0093] Embodiment 9 of the battery module in the present invention: The difference from the above embodiments is that the battery module in this embodiment not only includes end plates at the front and rear ends, but also includes side plates for protecting the left and right sides of the battery cell group. The side plates are connected to the end plates to form a frame surrounding the front, rear, left, and right sides of the battery cell group, and the heating film is arranged between the side plates and the battery cell group. When the side plates are connected to the end plates, the heating film can be pressed against the side of the battery cell group, enabling the heating film to heat the battery cell. Therefore, it is not limited to using the bonding method to relatively fix the heating film and the battery cell. In other embodiments, the frame formed by the side plates and the end plates can be used to tightly hold the battery cells in the front-rear direction to achieve relative fixation between the battery cells, and it is not limited to using the bonding method to fix the battery cells.

[0094] Embodiment 10 of the battery module in the present invention: The difference from the above embodiments is that elongated holes extending in the front-rear direction are also provided on the end plate connected to the movable end.

[0095] Embodiment 11 of the battery module in the present invention: The difference from the above embodiments is that both the front and rear ends of the heating film are movable ends, and elongated holes for sliding cooperation with the connecting member in the front-rear direction are provided on the movable ends and the end plate connected to the movable ends, so that the movable ends and the end plate connected to the movable ends can move relative to each other in the front-rear direction. In other embodiments, elongated slots for sliding cooperation with the connecting member in the front-rear direction are provided on the movable ends and the end plate connected to the movable ends. In this case, a fixing plate needs to be added to the movable end, and the elongated slot is provided on the fixing plate.

[0096] 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. These battery modules are connected in series or in parallel, and the structure of the battery module is the same as that of the battery module in the above battery module embodiments. The box body belongs to the conventional structure commonly used in the prior art. Therefore, the embodiments of the battery box in the present invention will not be repeated here.

[0097] The specific embodiments described above further elaborate on the invention purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Battery module, comprising: A plurality of battery cells are provided and stacked in the front-rear direction to form a battery cell group; End plates are arranged at the front and rear ends of the battery cell group; A heating film is arranged on at least one of the left side surface and the right side surface of the battery cell group for heating the battery cells; It is characterized in that A weak part extending vertically is provided on the heating film, and a long circular hole penetrating both sides of the heating film is provided on the weak part; The weak part extends in a direction perpendicular to the arrangement direction of the battery cells and is opposite to the stacking positions of two adjacent battery cells; there is a gap between the weak part on the heating film and the stacking positions of adjacent battery cells, and the long circular hole on the weak part communicates with the gap; the heating film is adhesively fixed to the battery cells, and adjacent battery cells are adhesively fixed to each other.

2. The battery module according to claim 1, wherein There is at least one pair of adjacent weak parts in the battery cell arrangement direction that satisfy: the long circular hole on one weak part is arranged upward, and the long circular hole on the other weak part is arranged downward.

3. The battery module according to claim 1, wherein, Both of the two adjacent weak parts in the battery cell arrangement direction satisfy: the long circular hole on one weak part is arranged upward, and the long circular hole on the other weak part is arranged downward.

4. The battery module according to claim 1, wherein, Heating films are arranged on both the left side surface and the right side surface of the battery cell group. Among the two weak parts on the left heating film and the right heating film that are opposite to the stacking positions of the same pair of adjacent battery cells, the long circular hole on one is arranged upward, and the long circular hole on the other is arranged downward.

5. The battery module according to any one of claims 1-4, characterized in that, The long circular hole in the weak part has an arc edge at at least one end in the direction perpendicular to the battery cell arrangement direction to prevent the heating film from being torn at this end.

6. The battery module according to claim 5, wherein The heating film is adhesively fixed to the battery cell group. At least one end of the front and rear ends of the heating film is a movable end. The front and rear ends of the heating film are respectively connected to the end plates at both ends through connecting pieces. The connecting pieces have a stop structure for restricting the movement of the end of the heating film away from the battery cell group. The end plate connected to the movable end is a movable end connection end plate; A long hole or a long slot for sliding cooperation with the connecting piece in the front-rear direction is provided on the movable end and / or the movable end connection end plate, so that the movable end and the movable end connection end plate can move relative to each other in the front-rear direction.

7. Battery box, comprising: A box body; A battery module is installed in the box body. It is characterized in that the battery module is the battery module according to any one of claims 1-6.

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