Battery pack

Abstract

The battery pack comprises a shell and a battery cell assembly, the shell comprises a lower cover, the lower cover is provided with a flexible middle frame and a flexible end plate, a limiting cavity is formed in the flexible middle frame, and the flexible end plate is located in the limiting cavity; the battery cell assembly is contained in the limiting cavity, the battery cell assembly comprises a plurality of single battery cells stacked in sequence, the battery cell assembly is provided with an end face perpendicular to the stacking direction of the single battery cells, and the flexible end plate abuts against the end face of the battery cell assembly. Therefore, the flexible constraint on the single battery cells in the stacking direction can be realized, the large surfaces of the single battery cells can be ensured to maintain relatively good flatness in the charging and discharging process of the single battery cells, and the problem of slippage among the single battery cells is avoided; in addition, the weight of the shell can be greatly reduced, so that the lightweight design of the battery pack is realized, and the grouping rate of the battery pack and the high specific energy of the battery pack are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery pack. Background Art

[0002] In recent years, in the field of aerospace, the leapfrog breakthrough of secondary battery energy density has become the focus of the battery industry. Taking lithium metal batteries as an example, the current energy density of lithium metal batteries can reach about twice that of traditional high-energy-density lithium-ion batteries. Therefore, lithium metal batteries have gradually become the new darling of the aerospace field. However, there are still many difficulties in the existing lithium metal battery grouping. For example, there is a "deep breathing" effect in the process of charging and discharging of single cells, which leads to a high thickness change rate of lithium metal batteries, which is not conducive to the charge and discharge cycle. At the same time, the "deep breathing" effect will also cause the expansion thickness of the single cell to be uneven, which will cause relative slip between the single cells, resulting in deformation of the lithium metal battery. Therefore, it is usually necessary to apply a restraining force in the stacking direction of the single cell. The conventional method is rigid restraint. For example, rigid structural parts such as steel strips and side plates are used to restrain the battery. However, this method will result in a large overall weight of the battery pack, making it difficult to achieve lightweight design, which will lead to a low grouping rate of the entire battery pack. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a battery pack, which can not only apply flexible constraints to the single cells in the thickness direction, but also achieve a lightweight design of the battery pack and improve the battery grouping rate.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] A battery pack comprises: a shell and a cell assembly, the shell comprising a lower cover, the lower cover having a flexible middle frame and a flexible end plate, a limiting cavity being formed on the flexible middle frame, the flexible end plate being located in the limiting cavity; the cell assembly is accommodated in the limiting cavity, the cell assembly comprises a plurality of single cells stacked in sequence, and the cell assembly has an end face perpendicular to the stacking direction of the single cells, and the flexible end plate abuts against the end face of the cell assembly.

[0006] In one of the embodiments, the flexible middle frame includes a first fiber cloth layer and a resin matrix, and the first fiber cloth layer is solidified and formed by the resin matrix.

[0007] In one embodiment, the first fiber cloth layer is a unidirectional fiber cloth layer.

[0008] In one embodiment, the flexible end plate includes a second fiber cloth layer and a composite sandwich panel, and the second fiber cloth layer is arranged on the outer surface of the composite sandwich panel.

[0009] In one embodiment, the second fiber cloth layer is a unidirectional fiber cloth layer.

[0010] In one embodiment, the composite sandwich panel includes a skin layer and a core layer, the skin layer is arranged on the outer surface of the core layer, and the skin layer is a fiber cloth composite resin layer.

[0011] In one embodiment, the fiber cloth composite resin layer is a carbon fiber cloth composite resin layer.

[0012] In one embodiment, the core material layer is a honeycomb structure board.

[0013] In one of the embodiments, a resin edge sealing layer is provided on the edge of the flexible end plate.

[0014] In one embodiment, the shell further includes an upper cover, and the upper cover is buckled and connected to the lower cover.

[0015] In one of the embodiments, a first glue filling groove and a second glue filling groove are provided on a side surface of the upper cover facing the side wall of the flexible middle frame, and adhesives of different properties are respectively provided on the first glue filling groove and the second glue filling groove.

[0016] In one embodiment, a barrier structure is disposed between the first glue filling groove and the second glue filling groove, and the barrier structure is used to separate the first glue filling groove and the second glue filling groove.

[0017] In one embodiment, the barrier structure includes a sealing ring and a sealing ring limiting groove, the sealing ring limiting groove is opened on a side surface of the upper cover facing the side wall of the flexible middle frame, the sealing ring is accommodated in the sealing ring limiting groove, and the sealing ring is abutted against the side wall of the flexible middle frame.

[0018] In one embodiment, the adhesive includes a sealant and a structural adhesive, the sealant is filled in the first glue filling groove, and the structural adhesive is filled in the second glue filling groove.

[0019] In one embodiment, the depth of the first glue filling groove is greater than the depth of the second glue filling groove.

[0020] In one embodiment, the first glue filling groove and / or the second glue filling groove is also provided with a glue overflow hole.

[0021] In one of the embodiments, the battery cell assembly further includes a buffer plate, the buffer plate abuts against a large surface of the single battery cell, and the buffer plate is perpendicular to a stacking direction of the single battery cell.

[0022] In one of the embodiments, the battery cell assembly further includes a bottom buffer sheet, and the bottom buffer sheet is disposed between the single battery cell and the bottom of the shell.

[0023] In one of the embodiments, an insulating sheet is further included, wherein the insulating sheet is disposed on the end surface of the battery cell assembly, and the insulating sheet is located between the battery cell assembly and the flexible end plate.

[0024] In one of the embodiments, a support block is provided on the top sealing gap of the single battery cell, and a gap between the support block and the inner wall of the upper cover is filled with flexible glue.

[0025] Compared with the prior art, the present invention has at least the following advantages:

[0026] The battery pack of the present invention uses the shell to limit the cell assembly, thereby realizing flexible restraint of the single cell in the stacking direction. Specifically, the flexible middle frame cooperates with the flexible end plate to realize flexible restraint of the single cell in the stacking direction, ensuring that the large surface of the single cell can maintain good flatness during the charging and discharging process of the single cell, avoiding the problem of slippage between the single cells; in addition, the flexible middle frame cooperates with the flexible end plate, and the weight of the shell can be greatly reduced compared with the existing rigid structural parts, thereby realizing the lightweight design of the battery pack, improving the grouping rate of the battery pack and the high specific energy of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below.

[0028] Figure 1 is a schematic structural diagram of a battery pack in one embodiment of the present invention;

[0029] Figure 2 for Figure 1 Schematic diagram of the explosion structure of the battery pack;

[0030] Figure 3 for Figure 2 A schematic diagram of the structure of the lower cover of the battery pack;

[0031] Figure 4 for Figure 3 Schematic diagram of the exploded structure of the lower cover;

[0032] Figure 5 for Figure 3 A schematic diagram of a top view structure of a flexible end plate;

[0033] Figure 6 for Figure 5A schematic diagram of the cross-sectional structure of the flexible end plate at AA;

[0034] Figure 7 for Figure 6 A schematic diagram of the local enlarged structure of the flexible end plate at D;

[0035] Figure 8 for Figure 5 A schematic diagram of the cross-sectional structure of the flexible end plate at BB;

[0036] Fig. 9 for Figure 5 A schematic cross-sectional view of the flexible end plate at CC;

[0037] Fig.10 for Figure 1 A schematic cross-sectional view of a battery pack;

[0038] Fig.11 for Fig.10 A schematic diagram of the partial enlarged structure of the battery pack at position E;

[0039] Fig.12 for Figure 2 A schematic diagram of the three-dimensional structure of the upper cover in FIG.

[0040] Fig.13 for Fig.12 A schematic cross-sectional structural diagram of the upper cover in FIG.

[0041] Fig.14 for Fig.13 A schematic diagram of the partial enlarged structure of the upper cover at position F; DETAILED DESCRIPTION

[0042] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings.

[0043] See also Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, a battery pack 10 includes: a shell 1000 and a battery cell assembly 2000, the shell 1000 includes a lower cover 1100, the lower cover 1100 has a flexible middle frame 1110 and a flexible end plate 1120, a limited cavity is formed on the flexible middle frame 1110, and the flexible end plate 1120 is located in the limited cavity; the battery cell assembly 2000 is accommodated in the limited cavity, the battery cell assembly 2000 includes a plurality of single battery cells 2100 stacked in sequence, and the battery cell assembly 2000 has an end face perpendicular to the stacking direction of the single battery cells 2100, and the flexible end plate 1120 is abutted against the end face of the battery cell assembly 2000.

[0044] It should be noted that, by combining the flexible middle frame 1110 with the flexible end plates 1120, flexible restraint of the single battery cells 2100 in the stacking direction can be achieved, ensuring that during the charging and discharging process of the single battery cells 2100, the large surfaces of the single battery cells 2100 can maintain good flatness, thereby avoiding slippage between the single battery cells 2100; in addition, by combining the flexible middle frame 1110 with the flexible end plates 1120, the weight of the shell can be greatly reduced compared to existing rigid structural parts, thereby achieving a lightweight design of the battery pack, and improving the battery pack grouping rate and the high specific energy of the battery pack.

[0045] Among them, the flexible middle frame 1110 includes a first fiber cloth layer and a resin matrix. The first fiber cloth layer is solidified and formed by the resin matrix. Specifically, the flexible middle frame 1110 uses fiber cloth as a reinforcement in a continuous winding manner, that is, the first fiber cloth layer is used as a reinforcement of the flexible middle frame, and then the resin is used as the matrix for molding and solidification. The flexible middle frame 1110 structure formed in this way has excellent mechanical properties, such as high tensile strength, which can ensure the limiting constraint of the battery cell assembly 2000, and is lighter and thinner, which can greatly reduce the overall weight of the upper cover 1200 and realize the lightweight design of the shell 1000.

[0046] In one embodiment, the flexible end plate includes a second fiber cloth layer 1121 and a composite sandwich panel 1122, wherein the second fiber cloth layer 1121 is disposed on the outer surface of the composite sandwich panel 1122; that is, the flexible end plate 1120 adopts a composite sandwich panel 1122 structure wrapped with the second fiber cloth layer 1121; wherein the composite sandwich panel 1122 refers to a structure formed by sandwiching a layer of lightweight core material with a composite skin, and this structure can ensure that the flexible end plate 1120 has better mechanical properties, such as higher The flexural strength and compression resistance, etc., can resist deformation. At the same time, the lightweight property of the composite sandwich panel 1122 is utilized, so the lightweight design of the shell 1000 can be greatly realized. By setting a second fiber cloth layer 1121 on the composite sandwich panel 1122, the electrochemical mechanical stress in the stacking direction of the single battery cell 2100 can be resisted by the second fiber cloth layer 1121. In addition, the second fiber cloth layer 1121 has the advantages of light weight and high strength, so the lightweight design of the shell 1000 can be greatly realized. Specifically, by forming a limiting cavity on the flexible middle frame 1110 and placing the battery cell assembly 2000 in the limiting cavity, the initial limiting constraint of the battery cell assembly 2000 is realized. Then, a flexible end plate 1120 is set on the end face of the battery cell assembly 2000, and the flexible end plate 1120 is used to further flexibly constrain the single battery cell 2100 in the stacking direction to improve the cycle life of the battery pack.

[0047] In this way, the flexible middle frame 1110 cooperates with the flexible end plate 1120 to limit the flexible position of the battery cell assembly 2000, so as to ensure that the large surface of the single battery cell 2100 can maintain a good flatness during the charging and discharging process of the single battery cell 2100, avoid the slip problem between the single battery cells 2100, and avoid the single battery cell 2100 from causing an internal short circuit due to excessive deformation of the single battery cell 2100; in addition, the flexible middle frame 1110 cooperates with the flexible end plate 1120, and the weight of the shell 1000 can be greatly reduced relative to the existing rigid structural parts, thereby realizing the lightweight design of the battery pack 10, improving the grouping rate of the battery pack 10 and the high specific energy of the battery pack 10. For example, the shell structure in the present invention is more suitable for lithium metal batteries with a higher thickness change rate, so the shell structure of the present invention can greatly play the advantages of the high specific energy of lithium metal batteries, and at the same time, it can also ensure the stability of the discharge performance of the lithium metal battery during the charging and discharging process and the high reliability and safety of the use process.

[0048] In one embodiment, the first fiber cloth layer can be a unidirectional fiber cloth layer or a woven fiber cloth layer. Preferably, the first fiber cloth layer is a unidirectional fiber cloth layer, and the unidirectional fiber cloth layer is formed by curing a resin matrix. Unidirectional fiber cloth refers to a fiber cloth having a large number of fiber filaments in one direction and a small number of fiber filaments in another direction, so that the unidirectional fiber cloth has extremely high strength and stability in a specific direction. In addition, the unidirectional fiber cloth also has the advantage of thin wall thickness. After compression molding and compaction, from the microstructural analysis, the gap between its fibers is much smaller than that of the woven fiber cloth. For example, the thinnest unidirectional fiber cloth can reach 0.03mm, while the thickness of the woven fiber cloth is generally 0.1mm-0.3mm. Therefore, the flexible middle frame 1110 with the same wall thickness is made of unidirectional fiber cloth and woven fiber cloth, for example, 0.5 mm wall thickness. The unidirectional fiber cloth structure can make the tensile strength of the interface of the formed flexible middle frame 1110 higher (along the fiber axis). This is not only reflected in the fact that the unidirectional fiber cloth of the flexible middle frame 1110 with the same wall thickness can be continuously wound for more turns, but also in the fact that the fiber content of the unidirectional fiber cloth is higher (the content of resin impregnated into the gap between fibers is less), so that the flexible middle frame 1110 can have higher tensile strength. Preferably, the unidirectional fiber cloth layer is a unidirectional carbon fiber cloth layer, a unidirectional aramid fiber cloth layer or a unidirectional glass fiber cloth layer.

[0049] In one embodiment, the second fiber cloth layer 1121 is a unidirectional fiber cloth layer 1121. That is, the second fiber cloth layer 1121 in the flexible end plate 1120 also adopts a unidirectional fiber cloth structure. The advantages of the unidirectional fiber cloth are the same as those of the above-mentioned first unidirectional fiber cloth layer, which will not be described in detail here. In this embodiment, the second fiber cloth layer 1121 can be a carbon fiber cloth layer 1121, an aramid fiber cloth layer 1121 or a glass fiber cloth layer 1121, preferably a carbon fiber cloth layer 1121. It should also be noted that the unidirectional fiber cloth layer 1121 is provided on the composite sandwich panel 1122 by continuous winding.

[0050] See also Figure 5 , Figure 6 , Figure 7 , Figure 8 and Fig. 9 As shown, in one embodiment, the composite sandwich panel 1122 includes a skin layer 1122a and a core material layer 1122b, wherein the skin layer 1122a is disposed on the outer surface of the core material layer 1122b, and the skin layer 1122a is a fiber cloth composite resin layer. The fiber cloth composite resin layer has better mechanical properties, such as higher bending strength, and the fiber cloth composite resin layer is lighter, so that the lightweight design of the shell 1000 can be achieved. The fiber cloth composite resin layer refers to a structural layer that uses fiber cloth as a reinforcement and resin as a matrix for curing and forming. The fiber cloth composite resin layer can be a carbon fiber cloth composite resin layer, an aramid fiber cloth composite resin layer or a glass fiber cloth composite resin layer. In this embodiment, the fiber cloth composite resin layer is preferably a carbon fiber cloth composite resin layer. For example, the carbon fiber cloth can be a woven carbon fiber cloth. The carbon fiber composite resin layer has a higher bending strength, which is generally more than six times that of 6 series aluminum and more than three times that of titanium alloy. However, its density is much lower than that of aluminum alloy or titanium alloy, so it can better meet the requirements of lightweight design.

[0051] See also Figure 6 , Figure 7 and Figure 8 As shown, in one embodiment, the core material layer 1122b is a honeycomb structure plate. The honeycomb structure plate has the advantages of light weight and high strength, that is, it can further ensure that the flexible end plate 1120 has stronger bending and compression resistance while achieving extreme lightweight. Specifically, the honeycomb structure plate includes a plurality of regular hexagonal honeycombs connected in combination, and the wall thickness of the regular hexagonal honeycombs is 0.04 to 0.05 mm. Preferably, the honeycomb structure plate is an aramid honeycomb structure plate or an aluminum alloy honeycomb structure plate. The honeycomb structure plate made of aramid material and the honeycomb structure made of aluminum alloy material have the advantages of high strength and light weight, so it can ensure the strength requirements of the flexible end plate 1120, and can further ensure the lightweight effect of the flexible end plate 1120.

[0052] See also Figure 6As shown, in another embodiment, in order to further reduce the weight of the flexible end plate 1120, the flexible end plate 1120 adopts a hollow sandwich structure, that is, the composite sandwich plate 1122 does not adopt the method of covering the flexible end plate 1120 with the entire surface, but arranges the composite sandwich plate 1122 on both sides of the flexible end plate 1120, and then wraps the composite sandwich plate 1122 by a fiber cloth continuous winding process, so that the material usage of the composite sandwich plate 1122 can be reduced, so that not only the strength of the flexible end plate 1120 can be ensured, and then the flexible binding effect on the stacking direction of the single battery cell 2100 can be ensured, but also the lightweight design of the shell 1000 can be further realized, and the grouping rate and high specific energy of the battery pack can be improved. In this embodiment, the overall height of the composite sandwich plate 1122 is 5mm to 7mm.

[0053] In one embodiment, in order to prevent the stress on the edge of the flexible end plate 1120 from being too concentrated when the flexible end plate 1120 is subjected to the expansion force of the single battery cell, a resin edge sealing layer 1123 is provided at the edge of the flexible end plate 1120. For example, a resin with a width of 3 mm to 6 mm is used to seal the edge of the large surface of the flexible end plate 1120, so that part of the stress can be absorbed and dispersed by the resin edge sealing layer 1123 to prevent the stress from being too concentrated on the edge of the flexible end plate 1120.

[0054] In one embodiment, the lower cover 1100 further includes a bottom plate 1130, which is disposed at the bottom of the flexible middle frame 1110. In this embodiment, the structure of the bottom plate 1130 may be the same as that of the flexible middle frame 1110, that is, a first fiber cloth layer and a resin matrix are used. In another embodiment, the structure of the bottom plate 1130 may also be the same as that of the above-mentioned skin layer 1122a, that is, a fiber cloth composite resin layer is used, for example, a woven carbon fiber cloth composite resin layer. In this way, the flexible middle frame 1110, the flexible end plate 1120 and the bottom plate 1130 all adopt a light and high-strength structure, thereby greatly realizing the lightweight design of the housing 1000, thereby improving the high specific energy of the battery, and also improving the flexible binding effect on the single battery cell 2100, ensuring the stability of the discharge performance of the single battery cell 2100 during the charging and discharging process and the high reliability and safety during the use process.

[0055] In one embodiment, in order to further improve the overall structural strength of the shell, the flexible middle frame 1110, the flexible end plate 1120 and the bottom plate 1130 are an integrally molded structure, that is, the flexible middle frame 1110, the flexible end plate 1120 and the bottom plate 1130 are molded by resin, so that the flexible middle frame 1110, the flexible end plate 1120 and the bottom plate 1130 are combined into a whole.

[0056] See also Figure 1 and Figure 2As shown, the housing 1000 further includes an upper cover 1200, and the upper cover 1200 is buckled and connected with the lower cover 1100. For example, the upper cover 1200 and the lower cover 1100 can be connected and fixed by gluing.

[0057] Furthermore, please combine Fig.10 , Fig.11 , Fig.12 , Fig.13 and Fig.14 As shown, a first glue filling groove 1210 and a second glue filling groove 1220 are provided on one side surface of the upper cover 1200 facing the side wall of the flexible middle frame 1110 , and adhesives of different properties are respectively provided on the first glue filling groove 1210 and the second glue filling groove 1220 .

[0058] It should be noted that the main purpose of using adhesives of different properties to connect the upper cover 1200 and the lower cover 1100 is to further achieve the ultimate lightweight effect of the housing 1000. Specifically, adhesives of different properties refer to using two adhesives of different properties, such as adhesives with different properties such as shear resistance and peel resistance. For example, the two adhesives are structural adhesive and sealant respectively, among which, the characteristic of sealant is: when the thickness of sealant is thicker, its peeling resistance is better, but if the sealant is required to have better shear resistance, the coating width of the sealant needs to be increased, then, when only sealant is used for glue bonding, it is necessary to correspondingly increase the contact surface between the upper cover 1200 and the side wall of the flexible middle frame 1110, which means that the volume of the upper cover 1200 needs to be increased, thus increasing the weight of the shell 1000, which is not conducive to the lightweight design of the shell 1000; and the characteristic of structural adhesive is: when the thickness of structural adhesive is thinner, its shear resistance is stronger, but the peeling resistance is poor, and making the structural adhesive thicker is also not conducive to the lightweight design of the shell 1000. Therefore, since both sealant and structural adhesive have their own disadvantages and advantages, after ensuring that the upper cover 1200 and the lower cover 1100 are glued together by the adhesive, they have both better peeling resistance and higher shear resistance, and can also achieve a more extreme lightweight effect of the shell 1000; therefore, in this embodiment, two adhesives of different properties are used to connect and fix the upper cover 1200 and the lower cover 1100, that is, the adhesive includes sealant and structural adhesive, the sealant is filled in the first glue filling groove 1210, and the structural adhesive is filled in the second glue filling groove 1220. Preferably, the depth of the first glue filling groove 1210 is greater than the depth of the second glue filling groove 1220, that is, the depth of the first glue filling groove 1210 filled with sealant is greater than the depth of the second glue filling groove 1220 filled with structural glue. Then, the thickness of the sealant can be made relatively thick to meet the peeling strength of the joint area between the upper cover 1200 and the lower cover 1100. For example, the thickness of the sealant is above 0.8 mm, and the thickness of the structural glue is made relatively thin to meet the shear resistance of the joint area between the upper cover 1200 and the lower cover 1100, thereby further realizing the ultimate lightweight design of the shell 1000.

[0059] Please refer again Fig.11 and Fig.14As shown, in order to prevent the adhesive in the first glue filling groove 1210 from contacting and mixing with the adhesive in the second glue filling groove 1220, thereby affecting the bonding effect between the upper cover 1200 and the lower cover 1100, in one embodiment, a blocking structure 1230 is provided between the first glue filling groove 1210 and the second glue filling groove 1220, and the blocking structure 1230 is used to separate the first glue filling groove 1210 and the second glue filling groove 1220 to prevent the adhesive in the first glue filling groove 1210 from contacting and mixing with the adhesive in the second glue filling groove 1220.

[0060] See also Fig.11 As shown, in one embodiment, the barrier structure 1230 includes a sealing ring 1231 and a sealing ring limiting groove 1232. The sealing ring limiting groove 1232 is provided on a side surface of the upper cover 1200 facing the side wall of the flexible middle frame 1110. The sealing ring 1231 is accommodated in the sealing ring limiting groove 1232, and the sealing ring 1231 abuts against the side wall of the flexible middle frame 1110. Specifically, the sealing ring 1231 is limited and fixed by the sealing ring limiting groove 1232. At the same time, after the upper cover 1200 and the lower cover 1100 are buckled and connected, the sealing ring 1231 abuts against the side wall of the flexible middle frame 1110, thereby preventing the adhesive in the first glue filling groove 1210 from contacting and mixing with the adhesive in the second glue filling groove 1220. In this embodiment, the sealing ring 1231 is interference fit between the upper cover 1200 and the lower cover 1100, that is, the side wall of the flexible middle frame 1110 squeezes the sealing ring 1231. This not only improves the isolation effect, but also ensures the consistency of the assembly gap between the upper cover 1200 and the lower cover 1100. The consistency of the assembly gap can make the consistency of the adhesive filling thickness better. Furthermore, in another embodiment, when the upper cover 1200 is made of a material with a certain elasticity, such as plastic or the like, the barrier structure 1230 can be a barrier protrusion, that is, a barrier protrusion is directly arranged on one side surface of the upper cover 1200 facing the side wall of the flexible middle frame 1110, and the barrier protrusion is abutted against the side wall of the flexible middle frame 1110, thereby achieving the function of separating the first glue filling groove 1210 and the second glue filling groove 1220. At the same time, since the barrier protrusion is elastic, it will not affect the snap-fit ​​connection between the upper cover 1200 and the lower cover 1100.

[0061] Furthermore, since the structure of the upper cover 1200 is relatively complex, and the expansion force of the battery pack is relatively large except for the expansion force of the single cell 2100 in the thickness direction, the expansion force of other positions can also be met by ordinary engineering plastics. Therefore, in order to reduce the difficulty of processing the upper cover 1200, thereby reducing the cost, and further realizing the lightweight design of the upper cover 1200, in one embodiment, the material of the upper cover 1200 is selected from plastics with high surface energy, such as polycarbonate. Plastic materials with high surface energy are more likely to form a good adhesion effect with adhesives, so the bonding stability between the upper cover 1200 and the lower cover 1100 can be further ensured.

[0062] In one embodiment, a glue overflow hole 1240 is further provided on the first glue filling groove 1210 or / and the second glue filling groove 1220. The glue overflow hole 1240 not only allows the adhesive to form an undercut structure after curing, thereby further improving the bonding stability of the adhesive, but also reduces the glue application accuracy requirements during the production process, thereby preventing the adhesive from overflowing onto the outer surface of the housing 1000 due to excessive filling.

[0063] See also Figure 2 As shown, the battery cell assembly 2000 also includes a buffer plate 2200, and the buffer plate 2200 is against the large surface of the single battery cell 2100, and the buffer plate 2200 is perpendicular to the stacking direction of the single battery cell 2100. During the charging and discharging process of the single battery cell 2100, the buffer plate 2200 can be used to absorb the expansion stress in the stacking direction of the single battery cell 2100, so as to further ensure the stability of the discharge performance during the charging and discharging process of the battery and the high reliability and high safety during use. For example, the buffer plate 2200 can be made of silicone rubber material with other structural filling materials added for foaming. In this way, the buffer plate 2200 can have the characteristics of low density, high resilience, and small stress loss after multiple cycles of compression, so as to ensure the buffering effect on the single battery cell 2100. In this embodiment, the number of buffer plates 2200 can be selected according to the number of single battery cells 2100. There are multiple buffer plates 2200 , some of which are located between two single cells 2100 , and some of which are located at both end surfaces of the stacked single cells.

[0064] See also Figure 2 As shown, in one embodiment, the battery cell assembly 2000 further includes a bottom buffer sheet 2300, which is disposed between the single battery cell 2100 and the bottom of the housing 1000. The bottom buffer sheet 2300 is used to absorb the expansion stress at the bottom of the single battery cell 2100. For example, the bottom buffer sheet 2300 is made of rubber or polyurethane.

[0065] See also Figure 2As shown, in one embodiment, the battery pack 10 further includes an insulating sheet 3000, which is disposed on the end surface of the battery cell assembly 2000, and the insulating sheet is located between the battery cell assembly and the flexible end plate. That is, two insulating sheets 3000 are provided, and the two insulating sheets 3000 are disposed on the two end surfaces of the battery cell assembly 2000, and the insulating sheet 3000 is used to achieve insulation protection for the battery cell assembly 2000. In this embodiment, the insulating sheet 3000 can be made of a plastic material with a smooth surface and self-lubricating properties, such as polyimide or polytetrafluoroethylene, so that the assembled battery cell assembly 2000 can be easily inserted into the limiting cavity of the lower cover 1100.

[0066] See also Figure 2 As shown, in one embodiment, a support block 2400 is provided on the top sealing gap of the single cell 2100, and the gap between the support block 2400 and the inner wall of the upper cover 1200 is filled with flexible glue. The top sealing gap of the single cell 2100 is filled by the support block 2400, and when the cell assembly 2000 is placed in the limiting cavity of the lower cover 1100, flexible glue is applied on the support block 2400, and the gap between the support block 2400 and the inner wall of the upper cover 1200 is filled by the flexible glue, so that the single cell 2100 can indirectly contact the housing 1000 through the support block 2400 and the flexible glue. Then, after the cell assembly 2000 is placed in the housing 1000, the force can be transmitted to the housing 1000, so that the environment required by the single cell 2100 can be maintained by relying on the strength and rigidity of the housing 1000. For example, the flexible glue may be a flexible foam glue, and the support block 2400 may be a low-density and high-hardness foam material, such as polyurethane, polypropylene, and the like.

[0067] It should also be noted that after the single battery cells 2100 are stacked and assembled, their series and parallel connection can be flexibly connected by means of ultrasonic welding of the tabs, and then the assembled battery cell assembly 2000 is placed in the limiting cavity of the lower cover 1100. Before closing the upper cover 1200, it is necessary to install the protective coil through the outlet hole of the upper cover 1200, weld the equalizing cable 4000 and the charging and discharging cable 5000, thereby completing the assembly of the battery pack.

[0068] In addition, it should be noted that through the above structure, the battery pack can have a higher protection level and drop resistance and impact resistance performance. For example, through the buffer plate 2200, the support block 2400, the bottom buffer sheet 2300 and other structures, the single battery cell 2100 can be kept away from the eight corners of the shell 1000, reducing the risk of collision between the shell 1000 and the single battery cell 2100, so that the battery pack can have the characteristics of impact resistance, high reliability, and high safety.

[0069] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A battery pack, characterized in that: include: A housing, the housing comprising a lower cover, the lower cover having a flexible middle frame and a flexible end plate, a limited cavity is formed on the flexible middle frame, and the flexible end plate is located in the limited cavity; and A battery cell assembly is accommodated in the limiting cavity, the battery cell assembly includes a plurality of single battery cells stacked in sequence, and the battery cell assembly has an end face perpendicular to the stacking direction of the single battery cells, and the flexible end plate abuts against the end face of the battery cell assembly.

2. The battery pack according to claim 1, characterized in that: The flexible middle frame includes a first fiber cloth layer and a resin matrix, and the first fiber cloth layer is solidified and formed by the resin matrix.

3. The battery pack according to claim 2, characterized in that: The first fiber cloth layer is a unidirectional fiber cloth layer.

4. The battery pack according to claim 1, characterized in that: The flexible end plate includes a second fiber cloth layer and a composite sandwich panel, wherein the second fiber cloth layer is arranged on the outer surface of the composite sandwich panel.

5. The battery pack according to claim 4, characterized in that: The second fiber cloth layer is a unidirectional fiber cloth layer.

6. The battery pack according to claim 4, characterized in that: The composite sandwich panel comprises a skin layer and a core material layer. The skin layer is arranged on the outer surface of the core material layer, and the skin layer is a fiber cloth composite resin layer.

7. The battery pack according to claim 6, characterized in that: The fiber cloth composite resin layer is a carbon fiber cloth composite resin layer.

8. The battery pack according to claim 6, characterized in that: The core material layer is a honeycomb structure plate.

9. The battery pack according to claim 4, characterized in that: The edges of the flexible end plates are provided with resin edge sealing layers.

10. The battery pack according to any one of claims 1 to 9, characterized in that: The shell also includes an upper cover, which is buckled and connected with the lower cover.

11. The battery pack according to claim 10, characterized in that: A first glue filling groove and a second glue filling groove are arranged on one side surface of the upper cover facing the side wall of the flexible middle frame, and adhesives of different properties are arranged on the first glue filling groove and the second glue filling groove respectively.

12. The battery pack according to claim 11, characterized in that: A barrier structure is provided between the first glue filling groove and the second glue filling groove, and the barrier structure is used to separate the first glue filling groove and the second glue filling groove.

13. The battery pack according to claim 12, characterized in that: The barrier structure includes a sealing ring and a sealing ring limiting groove. The sealing ring limiting groove is arranged on a side surface of the upper cover facing the side wall of the flexible middle frame. The sealing ring is accommodated in the sealing ring limiting groove, and the sealing ring is abutted against the side wall of the flexible middle frame.

14. The battery pack according to claim 12, characterized in that: The adhesive includes a sealant and a structural adhesive. The sealant is filled in the first glue filling groove, and the structural adhesive is filled in the second glue filling groove.

15. The battery pack according to claim 11, characterized in that: The depth of the first glue filling groove is greater than the depth of the second glue filling groove.

16. The battery pack according to claim 11, characterized in that: The first glue filling groove and / or the second glue filling groove is also provided with a glue overflow hole.

17. The battery pack according to any one of claims 1 to 9, characterized in that: The battery cell assembly further includes a buffer plate, the buffer plate abuts against a large surface of the single battery cell, and the buffer plate is perpendicular to a stacking direction of the single battery cell.

18. The battery pack according to any one of claims 1 to 9, characterized in that: The battery cell assembly further includes a bottom buffer sheet, which is arranged between the single battery cell and the bottom of the shell.

19. The battery pack according to any one of claims 1 to 9, characterized in that: It also includes an insulating sheet, which is arranged on the end surface of the battery core assembly and is located between the battery core assembly and the flexible end plate.

20. The battery pack according to claim 10, characterized in that: A support block is arranged on the top sealing gap of the single cell, and a gap between the support block and the inner wall of the upper cover is filled with flexible glue.

Images