Battery packs and electrical devices

Abstract

This invention relates to the field of battery technology and discloses a battery pack and an electrical device. The battery pack includes multiple pouch cells, each pouch cell including a casing. The casing includes two large surfaces facing each other along a first direction and two side surfaces facing each other along a second direction. The multiple pouch cells are arranged along the first direction. An outer shell, housing the pouch cells, includes side plates and a fixing member. The side plates are disposed opposite to the large surfaces; the fixing member is disposed opposite to the side surfaces. The side plates include an inner side plate and an outer side plate. Along the first direction, the inner side plate is closer to the pouch cell than the outer side plate. The fixing member is welded to the outer side plate via at least one welded portion, which faces the large surfaces. Thus, the inner side plate provides a certain degree of heat insulation, preventing the aluminum-plastic film from being damaged by high temperatures.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to battery packs and electrical devices. Background Technology

[0002] During the manufacturing process of pouch battery packs, due to insufficient mechanical strength of the aluminum-plastic film casing, when welding is performed on the side plates and fasteners that fix the pouch battery pack casing, the heat generated in the welding area acts on the adjacent aluminum-plastic film, causing thermal damage or melting. This results in a decrease in the sealing performance of the pouch battery, and electrolyte may leak out, thus negatively impacting the safety of the battery pack. Summary of the Invention

[0003] This invention provides a battery pack and an electrical device to solve the problem of poor battery pack safety caused by heat generated during the welding of the outer shell of the fixed soft-pack battery pack acting on the aluminum-plastic film, resulting in heat damage or melting.

[0004] In a first aspect, the present invention provides a battery pack, comprising: a plurality of pouch cells, each pouch cell including a housing, the housing including two large surfaces opposite each other along a first direction and two side surfaces opposite each other along a second direction, the plurality of pouch cells being arranged along the first direction, the first direction being perpendicular to the second direction; an outer casing for accommodating the pouch cells, the outer casing including side plates and fasteners, the side plates being disposed opposite each other to the large surfaces along the first direction; the fasteners being disposed opposite each other to the side surfaces along the second direction; the side plates including inner side plates and outer side plates, the inner side plates being closer to the pouch cells than the outer side plates along the first direction; the fasteners being welded to the outer side plates via at least one welding portion, the welding portion being opposite to the large surfaces.

[0005] Beneficial effects: The side panel has a double-layer structure, consisting of an inner side panel and an outer side panel. Along the first direction, the inner side panel is closer to the soft-pack battery than the outer side panel. The fastener is welded to the outer side panel through at least one welding part. This not only provides additional structural support, but also plays a certain role in heat insulation during the heat transfer from the outer side panel to the soft-pack battery. This significantly reduces the heat reaching the soft-pack battery casing, effectively avoiding the risk of damage to the aluminum-plastic film due to high temperature, thus protecting the integrity and safety of the soft-pack battery.

[0006] In a second aspect, the present invention also provides an electrical device comprising: a battery pack as described in the first aspect. Attached Figure Description

[0007] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the battery pack structure according to an embodiment of the present invention;

[0009] Figure 2 This is an exploded view of the battery pack according to an embodiment of the present invention; Figure 3 This is a side view of the battery pack according to an embodiment of the present invention; Figure 4 for Figure 3 Section AA along the middle; Figure 5 for Figure 4 Enlarged view of a portion of point M in the middle; Figure 6 This is a simplified cross-sectional view of the housing according to an embodiment of the present invention.

[0010] Explanation of reference numerals in the attached figures: 1-Pouch battery; 10-Casing; 11-Main surface; 12-Side surface; 13-Outer insulating layer; 14-Intermediate metal layer; 15-Inner adhesive layer; 2-Outer shell; 21-Side panel; 211-Inner side panel; 212-Outer side panel; 22-Fastening component; 24-Fastener; 23-Welded part; 25-Top plate; 26-End plate; 27-Rib; 3-Cushioning pad; X - First direction; Z - Second direction; Y - Third direction. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] During the manufacturing process of pouch battery packs, due to insufficient mechanical strength of the aluminum-plastic film shell, when welding is performed on the side plate and fasteners that fix the pouch battery pack shell, the heat generated in the welding area acts on the adjacent aluminum-plastic film through heat conduction, causing thermal damage or melting of the nylon layer on the outer layer of the aluminum-plastic film. This results in a decrease in the sealing performance of the pouch battery, and electrolyte may leak out, which in turn has a negative impact on the safety of the battery pack.

[0013] In this regard, refer to Figures 1 to 6 This application proposes a battery pack, comprising: a plurality of pouch cells 1, each pouch cell 1 including a housing 10, the housing 10 including two large surfaces 11 opposite each other along a first direction X and two side surfaces 12 opposite each other along a second direction Z, the plurality of pouch cells 1 being arranged along the first direction X, the first direction X being perpendicular to the second direction Z; an outer shell 2 for housing the pouch cells 1, the outer shell 2 including a side plate 21 and a fixing member 22, the side plate 21 being opposite to the large surfaces 11 along the first direction X; the fixing member 22 being opposite to the side surfaces 12 along the second direction Z; the side plate 21 including an inner side plate 211 and an outer side plate 212, the inner side plate 211 being closer to the pouch cell 1 than the outer side plate 212 along the first direction X; the fixing member 22 being welded to the outer side plate 212 by at least one welding part 23, the welding part 23 being opposite to the large surfaces 11.

[0014] The battery pack is composed of multiple pouch cells 1 connected in series, parallel, or series-parallel.

[0015] The soft-pack battery 1 uses aluminum-plastic film as the outer packaging material, which has good shape plasticity, but the aluminum-plastic film outer shell 2 is relatively fragile and easily damaged by external factors. The casing 10 can be an aluminum-plastic film that wraps around the battery cell, used to isolate the battery cell from the external environment, prevent electrolyte leakage, and provide protection.

[0016] The large surface 11 of the housing 10 along the first direction X is the surface with the largest surface area among all surfaces of the housing 10. The first direction X can be the thickness direction of the pouch battery 1. The second direction Z can be the height direction of the pouch battery 1, i.e., the vertical direction. The third direction Y can be the length direction of the pouch battery 1. The two side surfaces 12 of the housing 10 along the second direction Z are two narrower surfaces of the housing 10.

[0017] The pouch battery 1 includes a casing 10 and a battery cell disposed within the casing 10. The battery cell is the component in the battery where electrochemical reactions occur; it is the smallest unit in the battery capable of electrochemical reactions such as charging / discharging. The battery cell is the basic unit of the battery and typically includes a positive electrode, a negative electrode, and a separator. Lithium-ion battery cells primarily function by the movement of lithium ions between the positive and negative electrodes. In a cuboid battery cell, the positive electrode, negative electrode, and separator are wound or stacked into an electrode assembly with a generally cuboid shape.

[0018] The outer casing 2 is the external protective structure of the battery pack, used to house and secure the internal pouch cell 1. Side panels 21 are positioned opposite to the two large surfaces 11 of the pouch cell 1, thereby providing support and constraint in the thickness direction of the pouch cell 1. Fasteners 22 are positioned opposite to the side surfaces 12 of the pouch cell 1 to provide protection for the top or bottom of the battery pack.

[0019] The side panel 21 of the outer casing 2 includes an inner side panel 211 and an outer side panel 212, with the inner side panel 211 closer to the pouch battery 1 than the outer side panel 212. The outer side panel 212 is further away from the pouch battery 1 than the inner side panel 211, serving to provide protection. The inner side panel 211 can be a metal plate or a plastic plate. The outer side panel 212 can be a metal plate. Preferably, both the inner side panel 211 and the outer side panel 212 are metal plates, such as aluminum plates or aluminum alloy plates.

[0020] The welded part 23 is a molten structure formed by a welding process. Welding methods include, but are not limited to, laser welding, resistance welding, brazing, ultrasonic welding, and friction welding.

[0021] The side plate 21 has a double-layer structure, consisting of an inner side plate 211 and an outer side plate 212. Along the first direction X, the inner side plate 211 is closer to the soft-pack battery 1 than the outer side plate 212. The fastener 22 is welded to the outer side plate 212 through at least one welding part 23. The inner side plate 211 not only provides additional structural support, but also plays a certain role in heat insulation during the process of welding heat being conducted from the outer side plate 212 to the soft-pack battery 1. This significantly reduces the heat reaching the housing 10 of the soft-pack battery 1, thereby effectively avoiding the risk of damage to the aluminum-plastic film due to high temperature, thus protecting the sealing and safety of the soft-pack battery 1.

[0022] In some embodiments, the housing 10 includes an outer insulating layer 13 with a thickness of B μm. The ratio d / L of the maximum depth d mm of the welded portion 23 along the first direction X to the total thickness L mm of the side plate 21 is K, where B / K ranges from 15.2 μm to 350 μm. For example, it can be any one of 15.2 μm, 30 μm, 50 μm, 75 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, and 350 μm, or a range between any two.

[0023] The casing 10 of the pouch battery 1 is typically composed of multiple layers of materials, with the outermost insulating layer 13 serving as the main outermost layer. Its primary function is to provide electrical insulation, prevent short circuits, and protect the internal battery cells. This outer insulating layer 13 can be made of one or more materials such as polycaprolactam (nylon 6), PET (polyethylene terephthalate), or polybutylene succinate. The casing 10 also includes an intermediate metal layer 14, which can be made of one or more metals or alloys such as aluminum, aluminum alloy, copper, or nickel. The casing 10 may also include an inner adhesive layer 15 (insulating layer), which can be made of one or more materials such as polypropylene film (PP) or cast polypropylene film (CPP).

[0024] The maximum depth dmm of the weld portion 23 along the first direction X refers to the maximum dimension of the weld penetration in the first direction X. By controlling the ratio of the thickness Bμm of the outer insulation layer 13 to the maximum depth dmm of the weld portion 23 along the first direction X, the conduction of welding heat to the pouch battery 1 can be effectively suppressed, thereby reducing the risk of thermal damage to the outer insulation layer 13 of the pouch battery 1 casing 10 and ensuring that the outer insulation layer 13 is less susceptible to damage when subjected to welding heat, thus maintaining its integrity. At the same time, it avoids the risk of breakage due to excessively low strength of the weld portion 23 between the fastener 22 and the outer side plate 212, and also avoids the outer insulation layer 13 being too thick, occupying too much space and affecting the energy density of the battery pack.

[0025] The total thickness Lmm of the side plate 21 refers to the overall thickness of the side plate 21 of the housing 2 in the first direction X, which can be formed by superimposing the thicknesses of the inner side plate 211 and the outer side plate 212. A suitable total thickness L of the side plate 21 helps to effectively disperse welding heat while providing sufficient support.

[0026] The ratio K represents the proportion of the weld depth d to the total thickness L of the side plate 21. By controlling the value of K, excessive heat conduction to the pouch cell 1 can be suppressed while ensuring weld strength.

[0027] By controlling the B / K ratio, it is ensured that the outer insulation layer 13 can effectively resist the erosion of welding heat under different welding conditions. When the K value is large (the welding depth is relatively deep), a larger B value (a thicker outer insulation layer 13) is required to provide stronger heat resistance; when the B value is small (a thinner outer insulation layer 13), the K value needs to be limited (a shallower welding depth) to reduce the impact of heat.

[0028] By controlling the B / K ratio within the range of 15.2μm to 350μm, the conduction of welding heat to the interior of the pouch cell 1 can be optimized while ensuring the structural strength of the outer casing 2. When the welding heat is high, a thicker outer insulation layer 13 can provide stronger heat barrier capabilities; when the outer insulation layer 13 is thinner, the heat impact can be reduced by controlling the welding depth. This not only effectively protects the fragile aluminum-plastic film casing 10 of the pouch cell 1, avoiding problems such as cell material loss due to heat damage, but also takes into account the overall structural strength of the battery pack, as well as its volume utilization and energy density, avoiding space waste caused by excessive protection. Therefore, this solution significantly improves the manufacturing reliability, usage safety, and overall performance of the battery pack.

[0029] In some embodiments, the thickness Bμm of the outer insulating layer 13 ranges from 0.01μm to 0.04μm; Bμm can be any one of 0.01μm, 0.02μm, 0.03μm, 0.04μm or any range between two of them.

[0030] And / or, the ratio K of the maximum depth d of the welded portion 23 along the first direction X to the total thickness L of the side plate 21 is in the range of 0.1 to 0.7. For example, it can be any one of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or a range between any two. The maximum depth d of the welded portion 23 along the first direction X is the maximum depth of the molten pool formed in the welded portion after welding, that is, the distance from the surface of the welded portion to the deepest point of the molten pool.

[0031] If the thickness Bμm of the outer insulation layer 13 is too small, it may cause damage due to welding heat penetration; if the thickness Bμm of the outer insulation layer 13 is too large, the volumetric energy density of the battery pack will be low. When the range of Bμm is limited to 0.01μm to 0.04μm, it ensures that the outer insulation layer 13 has sufficient thickness to withstand welding heat, prevent heat penetration, and also helps to improve the volumetric energy density of the battery pack.

[0032] When the K value is too small, it may result in insufficient welding strength and a weak connection; when the K value is too large, the welding heat penetrates deeper and is closer to the inner side plate 211 and the pouch battery 1, increasing the risk of thermal damage. By controlling K within the range of 0.1 to 0.7, the transfer of heat to the pouch battery 1 can be minimized while ensuring sufficient welding strength.

[0033] In this application, measuring instruments such as micrometers or calipers can be used to measure parameters such as the length, width, distance, and thickness (e.g., B, L) of each structure.

[0034] Method for measuring the maximum depth d of the welded part 23 along the first direction X: For all welded parts in the battery pack, cut along the welded part, observe the visible weld pool area, measure the depth of the bottom of the weld pool area, and take the maximum value as the maximum depth d of the welded part 23 along the first direction X.

[0035] In some embodiments, the distance D1mm between the welded portion 23 and the housing 10 along the first direction X ranges from 2.5mm to 20mm. For example, it can be any one of 2.5mm, 3mm, 5mm, 10mm, 13mm, 15mm, 18mm, 20mm, or a range between any two of them.

[0036] If the distance D1mm between the welded part 23 and the casing 10 is too close, the heat generated by welding will be directly conducted to the fragile aluminum-plastic film casing 10, which may damage or melt its nylon layer, leading to battery failure and safety hazards. If the distance D1mm between the welded part 23 and the casing 10 is too far, it may result in insufficient weld penetration, resulting in insufficient weld strength between the casing 10 and the cover, a high risk of cracking, and inability to effectively protect the soft-pack battery 1.

[0037] By limiting the spacing D1mm to within the range of 2.5mm to 20mm, thermal protection is ensured while avoiding problems such as loose battery pack structure, reduced space utilization, or insufficient welding strength that may result from excessive spacing. This effectively reduces the damage to the pouch cell casing 10 caused by welding heat while maintaining the overall structural stability and compactness of the battery pack, thereby improving the safety and reliability of the battery pack.

[0038] In some embodiments, along the third direction Y, the welded portion 23 is offset from the center of the outer side plate 212, and the offset dimension ranges from 10mm to 75mm. The third direction Y, the first direction X, and the second direction Z are perpendicular to each other. The value can be any one of 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 75mm, or any range between two of them.

[0039] The center of the outer side plate 212 is set as the geometric center of the outer side plate 212. Since the outer side plate 212 is opposite to the large surface 11 of the soft-pack battery 1, the center of the outer side plate 212 corresponds to the center of the large surface 11 where the expansion is large. Therefore, by setting the welding part 23 off from the center of the outer side plate 212, the large expansion center area of ​​the large surface 11 is avoided, preventing the welding part 23 from cracking and ensuring the structural connection reliability of the outer casing 2.

[0040] In some embodiments, along the third direction Y, the minimum distance D3mm between the welded portion 23 and the edge of the outer side plate 212 ranges from 5mm to 35mm. For example, it can be any one of 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm or any combination thereof.

[0041] The welded portion 23 can be a continuous weld or multiple discrete weld points. When the welded portion 23 is a weld, the minimum distance between the end of the weld closest to the edge of the outer plate 212 and that edge along the third direction Y is D3. Figure 3 (As shown). When the welded part 23 consists of multiple discrete weld points, the minimum distance between the weld point closest to the edge and the edge of the outer plate 212 along the third direction Y is D3.

[0042] By controlling D3mm within the range of 5mm to 35mm, welding heat and stress can be effectively dispersed, avoiding excessive concentration in the end area and reducing the risk of material fatigue and failure caused by thermal stress.

[0043] In some embodiments, along the second direction Z, the welding portion 23 is offset from the center of the pouch battery 1, and the offset dimension D4mm ranges from 10mm to 40mm. D4mm can be any one of 10mm, 20mm, 30mm, and 40mm, or a range between any two of them.

[0044] By offsetting the welded part 23 from the center of the outer side plate 212, the central area of ​​the large surface 11 with greater expansion is avoided, preventing the welded part 23 from cracking and ensuring the structural connection reliability of the outer shell 2.

[0045] In some embodiments, along the second direction Z, the minimum distance D5mm between the welded portion 23 and the edge of the outer side plate 212 is ( Figure 3 (As shown) The range is 5mm to 35mm. For example, it can be any one of 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm or any two of them.

[0046] By controlling D5mm within the range of 5mm to 35mm, welding heat and stress can be effectively dispersed, avoiding excessive concentration in the end area and reducing the risk of material fatigue and failure caused by thermal stress.

[0047] In some embodiments, multiple welding portions 23 are provided along the third direction Y, and the spacing D6mm between two adjacent welding portions 23 ranges from 15mm to 60mm. The third direction Y, the first direction X, and the second direction Z are perpendicular to each other. D6mm can be any one of 15mm, 20mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, and 60mm, or a range between any two of them.

[0048] If the spacing distance D6mm is too small, it may lead to heat concentration, increasing the risk of damage to the aluminum-plastic film of the pouch battery 1; if the spacing distance D6mm is too large, it may weaken the connection strength of the outer casing 2, affecting the structural stability. Therefore, D6mm is controlled within the range of 15mm~60mm. While ensuring the connection strength between the fastener 22 and the outer panel 212, it reduces the concentration of welding heat, thereby effectively protecting the pouch battery 1 near the outer panel 212.

[0049] In some embodiments, the projected area of ​​a single welded portion 23 in the first direction X ranges from 100 mm. 2 ~3000mm 2 For example, it can be 100mm. 2 500mm 2 1000mm 2 1500mm 2 2000mm 2 2500mm 2 3000mm 2 The range of values ​​between any one or any two of them.

[0050] If the projected area is too small, the connection strength of the outer casing 2 may be insufficient, leading to a high risk of weld cracking and potential connection failure when the battery pack is subjected to vibration or impact. If the projected area is too large, the heat input during welding will increase significantly. This heat will be conducted to the casing 10 of the pouch battery 1 through the outer side plate 212 and the inner side plate 211, particularly its fragile aluminum-plastic film, potentially causing damage or melting due to overheating, thus affecting battery safety. Therefore, the projected area is limited to 100 mm². 2 Up to 3000mm 2 Within a certain range, this design ensures that the welded joint has sufficient mechanical strength to resist external stress while effectively controlling the input of welding heat, preventing excessive heat accumulation and transfer to the pouch cell 1, thereby protecting the pouch cell 1 from thermal damage. This design balances structural strength with thermal management requirements, improving the overall safety and reliability of the battery pack.

[0051] In some embodiments, the fastener 22 is a metal cable tie, and the two ends of the metal cable tie are respectively welded to two outer side plates 212 opposite to each other along the first direction X.

[0052] Metal cable ties are strip-shaped structures made of metal. They can be made from various metal materials, such as stainless steel, which has good mechanical strength and corrosion resistance, or aluminum alloy, which is lightweight.

[0053] By welding the two ends of the metal cable tie to the two outer side plates 212 opposite to each other along the first direction X, the outer casing 2 forms a stable support and fixing structure, which also helps to reduce the overall weight of the battery pack.

[0054] In some embodiments, the housing 2 further includes a top plate 25 disposed opposite to the metal cable tie along the second direction Z; along the second direction Z, both ends of the metal cable tie are disposed off-center from the center of the large surface 11 and close to the end of the outer side plate 212 away from the top plate 25.

[0055] Because the center of the large surface 11 of the pouch battery expands significantly during cycling, both ends of the metal cable tie are offset from the center of the large surface 11. This reduces the binding of the metal cable tie on the large surface 11, avoids the risk of the electrode falling off due to excessive binding, and improves the safety and reliability of the battery pack.

[0056] In some embodiments, the top plate 25 and the inner side plate 211 are integrally formed.

[0057] By designing the top plate 25 and the inner side plate 211 as an integral part, the two do not need to be welded, eliminating the impact of the additional welding heat on the soft-pack battery 1 and further improving the reliability of the soft-pack battery 1.

[0058] In some embodiments, the housing 2 further includes two end plates 26 facing each other along a third direction Y. The top plate 25, together with the two side plates 21 and the two end plates 26, forms a housing 2 with an opening on one side, wherein the third direction Y, the first direction X, and the second direction Z are perpendicular to each other. The two end plates 26 can be fixedly connected to the two side plates respectively. The connection can be made by bolts, screws, adhesive, snap-fit, or other means. For example, the top plate 25 and the two side plates 21 are integrally formed in a U-shape.

[0059] The end plate 26 can be made of a metallic material, such as a steel plate or an aluminum alloy plate, to ensure sufficient strength and rigidity to resist external impacts and pressure.

[0060] By using two end plates 26 opposite each other along the third direction Y, and having the top plate 25 together with the two side plates 21 and the two end plates 26 to form a shell 2 with an opening on one side, the overall structural rigidity of the shell 2 is enhanced, thereby reducing the impact of external mechanical shock on the soft-pack battery 1 and improving the overall safety and reliability of the battery pack.

[0061] In some embodiments, the outer side plate 212 has a first region with a rib 27 and a second region without a rib 27. The rib 27 protrudes along the first direction X toward the side opposite to the soft-pack battery 1, and the welding part 23 is located in the second region.

[0062] The raised rib 27 can be formed into a raised or recessed rib-like structure by local plastic deformation (such as stamping or stretching) on ​​the outer side plate 212. The raised rib 27 can improve the overall structural strength and deformation resistance of the outer side plate 212, thereby better protecting the internal pouch battery 1.

[0063] The rib 27 protrudes along the first direction X toward the side opposite to the pouch battery 1, ensuring that the rib 27 does not encroach on the internal space of the battery pack, and at the same time avoids direct contact between the rib 27 and the pouch battery 1 casing 10, thereby reducing the risk of material loss due to battery expansion squeezing the electrode sheets. The welding part 23 is located in the second area where the rib 27 is not provided, which helps to improve the welding quality and ensure the welding reliability of the casing 10.

[0064] In some embodiments, the inner side plate 211 is connected to the outer side plate 212 where the first area is located by fasteners 24.

[0065] Because the first zone is provided with ribs 27, the first zone has high strength. The first zone with high strength is connected to the inner side plate 211 by fasteners 24. The enhanced structural strength of the first zone itself is utilized to ensure the reliability of the connection between the inner side plate 211 and the outer side plate 212.

[0066] Fasteners 24 can take many forms. For example, they can be mechanical fasteners, such as bolts, rivets, self-tapping screws, etc.; they can also be adhesives, such as structural adhesives, epoxy resin adhesives, etc.; or they can be snap-fit ​​structures, which can achieve quick assembly and fixation by designing corresponding slots and tongues on the plate.

[0067] In some embodiments, along the first direction X, the distance C1mm between the second region and the inner side plate 211 ranges from 2mm to 8mm. For example, it can be any one of 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, or any combination thereof.

[0068] Because there is a 2mm to 8mm gap between the outer side plate 212 and the inner side plate 211, the path for heat to be conducted from the outer side plate 212 to the inner side plate 211 is effectively extended, reducing the efficiency and speed of heat conduction and further reducing the risk of heat being conducted to the pouch battery 1. At the same time, it avoids the problem of low volumetric energy density of the battery pack caused by an excessively large C1mm, and also ensures the compactness and stability of the battery pack structure.

[0069] In some embodiments, the pouch battery 1 group further includes a buffer pad 3, which is disposed between the inner side plate 211 and the large surface 11 of the pouch battery 1; and / or, a buffer pad 3 is disposed between at least two adjacent large surfaces 11 of the pouch battery 1.

[0070] The cushioning pad 3 has a certain degree of elasticity and compressibility, and also has a certain degree of thermal insulation. The cushioning pad 3 can be made of a variety of materials. For example, it can be made of silicone foam, which has good elasticity and high temperature resistance; or it can be made of polyurethane foam, which has excellent shock absorption and thermal insulation effects.

[0071] A buffer pad 3 is provided between the inner side plate 211 and the large surface 11 of the pouch battery 1, forming a protective layer between the inner side plate 211 of the outer casing 2 and the large surface 11 of the pouch battery 1. This buffer pad 3 can effectively absorb and block the heat transferred from the inner side plate 211, thereby preventing the aluminum-plastic film of the pouch battery 1 from being damaged due to high temperature. At the same time, the elastic properties of the buffer pad 3 can absorb and disperse the expansion stress during battery cycling, reducing the risk of electrode material falling off due to the outer casing 2 squeezing the pouch battery 1. A buffer pad 3 is provided between the large surfaces 11 of at least two adjacent pouch batteries 1. When the battery pack is subjected to external impact or vibration, the deformation of the buffer pad 3 absorbs the impact energy, preventing wear or compression deformation between the pouch batteries 1 due to direct contact, thereby enhancing the mechanical stability and safety of the entire battery pack.

[0072] In some embodiments, the housing 10 includes an outer insulating layer 13 with a thickness of B, and the ratio d / L of the maximum depth d of the welded portion 23 along the first direction X to the total thickness L of the side plate 21 is K, wherein B / K ranges from 15.2 μm to 300 μm; along the first direction X, the sum of the thicknesses of the plurality of buffer pads 3 is greater than or equal to 10 mm.

[0073] By controlling the B / K ratio within the range of 15.2μm to 300μm, the outer insulation layer 13 effectively blocks heat transfer to the interior of the pouch battery 1 during welding. Simultaneously, the depth to which welding heat penetrates the side plate 21 is limited, preventing excessive heat concentration. Furthermore, buffer pads 3 are provided between the inner side plate 211 and the large surface 11 of the pouch battery 1, or between adjacent large surfaces 11 of the pouch battery 1. The sum of the thicknesses of multiple buffer pads 3 along the first direction X is ensured to be greater than or equal to 10mm. When welding heat is transferred through the outer side plate 212 and the inner side plate 211, it first encounters the optimized thickness of the outer insulation layer 13 for initial blocking, and then is further absorbed, dispersed, and buffered by the sufficiently thick buffer pads 3. This achieves multiple layers of protection, significantly enhancing the heat insulation and buffering performance of the battery pack. This ensures that even when the welding part 23 is close to the pouch battery 1 during the welding of the outer casing 2, welding heat can effectively prevent damage to the fragile aluminum-plastic film of the pouch battery 1, thereby ensuring the safety and reliability of the battery.

[0074] In some embodiments, along the first direction X, the thickness of a single buffer pad 3 ranges from 1.5 mm to 3 mm, for example, it can be any one or any two of 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, and 3 mm.

[0075] The ratio of the thickness of a single buffer pad 3 to the thickness of a single pouch battery 1 ranges from 0.05 to 0.2. For example, it can be any one of 0.05, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2 or any two of them.

[0076] When the thickness of the buffer pad 3 is in the range of 1.5mm to 3mm, it can ensure that it has sufficient deformation space to absorb external impact force, while providing effective thermal resistance to prevent welding heat from being directly transferred to the soft-pack battery 1.

[0077] The ratio of the thickness of a single cushioning pad 3 to the thickness of a single pouch battery 1 is in the range of 0.05 to 0.2, which ensures that the cushioning pad 3 can provide a matching protective effect regardless of the size of the pouch battery 1. For example, when the pouch battery 1 is thicker, the thickness of the cushioning pad 3 is increased accordingly to provide sufficient cushioning capacity; when the pouch battery 1 is thinner, the thickness of the cushioning pad 3 is reduced accordingly to avoid unnecessary space waste.

[0078] In some embodiments, the thermal conductivity of the cushioning pad 3 is 1 W / (m·K); and / or, the elastic modulus of the cushioning pad 3 is from 0.1 MPa to 30 MPa. For example, it can be any one of 0.1 MPa, 1 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, or a range between any two of them.

[0079] The thermal conductivity of the buffer pad 3 is set to 1 W / (m·K) to ensure that the buffer pad 3 can effectively conduct away the heat generated by the soft-pack battery 1 during operation or welding, and avoid excessive heat accumulation in local areas.

[0080] The elastic modulus of the buffer pad 3 is controlled within the range of 0.1MPa to 30MPa to ensure that the buffer pad 3 has appropriate deformation capacity and energy absorption capacity when subjected to external pressure or impact, thereby effectively protecting the soft-pack battery 1 and avoiding damage.

[0081] In some embodiments, an insulating member is provided between the inner side plate 211 and the outer side plate 212, and the thickness of the insulating member ranges from 1 mm to 5 mm. For example, it can be any one of 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm, or a range between any two.

[0082] The insulating component can be made of plastic, rubber, or other insulating materials. The plastic can be polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), or polyvinyl chloride (PVC). The rubber can be fluororubber, nitrile rubber, or isobutyl rubber.

[0083] In some embodiments, an insulating layer is provided on the surface of the inner side plate 211 facing the soft-pack battery 1 along the first direction X; and / or, the outer casing 2 is a steel casing. The insulating layer may be an insulating film or an insulating coating.

[0084] The insulating film can be at least one of polyester film (PET, Polyethylene Terephthalate), polyimide (PI), polypropylene (PP), or polyethylene (PE).

[0085] The insulating coating material can be at least one of the following: (1) modified epoxy resin; (2) polyacrylate; (3) polyethylene phthalate (PET); (4) the insulating coating material also includes oil-based insulating resin or water-based insulating resin as the main material. The main material of the insulating resin includes epoxy resin, acrylic resin, polyurethane resin, hydroxyl acrylic resin and other multifunctional resins. The insulating material may also include a variety of additives, such as photoinitiators, reactive diluents, flame retardants, wetting agents, leveling agents, defoamers, etc.; (5) polyimide coating or insulating coating formed by polymers such as polyimide (PI) and epoxy resin; (6) styrene-butadiene rubber emulsion.

[0086] The inner side plate 211 is mainly used to protect the pouch battery 1. When the inner side plate 211 is in direct contact with the aluminum-plastic film shell 10 of the pouch battery 1, there is a risk that the aluminum-plastic film may be damaged due to friction, compression, or external heat sources (such as welding heat), which may lead to electrical short circuit or thermal runaway. By providing an insulating layer along the first direction X between the inner side plate 211 and the pouch battery 1, the insulating layer can effectively isolate the electrical contact between the inner side plate 211 and the pouch battery 1, thereby preventing the risk of short circuit. At the same time, the insulating layer can also reduce the heat transferred from the inner side plate 211 to the pouch battery 1, especially when the outer shell 2 is being welded, it can effectively protect the aluminum-plastic film of the pouch battery 1 from high-temperature damage.

[0087] When the outer casing 2 is made of steel, it can provide better mechanical strength and rigidity for the battery pack, thereby better protecting the internal pouch battery 1 from external impacts and vibrations.

[0088] This application also proposes an electrical device that includes a battery pack. The battery pack is used to provide a stable and reliable power supply for the electrical device.

[0089] Battery packs can serve as the operating power source for electrical devices, or as the driving power source for electrical devices, replacing or partially replacing fuel or natural gas to provide driving power for vehicles. Electrical devices include: energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other technological fields.

[0090] There are multiple battery packs, which can be connected in series, in parallel, or in a mixed manner. A mixed connection means that multiple battery packs are connected in both series and parallel.

[0091] Multiple battery packs can be connected in series to form a cluster-level battery structure, where the number of battery packs in each cluster is strictly configured according to voltage and capacity requirements. Specifically, a battery pack includes multiple battery cells, some of which are connected in series to form a cluster that meets a preset power supply voltage requirement, and at least one spare battery cell among the multiple battery cells is bypassed.

[0092] Example 1: Preparation of the battery pack (1) Preparation of the positive electrode: The positive electrode active material, conductive agent acetylene black, and binder PVDF are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, it is cold-pressed and slit to obtain the positive electrode sheet. Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98):(4~1):(4~1).

[0093] (2) Preparation of negative electrode: The negative electrode active material, conductive agent acetylene black, thickener CMC, and binder SBR are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the negative electrode sheet is obtained. The ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0094] (3) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0095] (4) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0096] (5) Preparation of pouch cells: The positive electrode, separator, and negative electrode are stacked in sequence to form a bare battery cell. The bare cell is then placed in a casing made of aluminum-plastic film. The first inner insulating layer of the aluminum-plastic film casing is made of cast polypropylene film (CPP), the second metal layer is made of aluminum, and the third outer insulating layer is made of polycaprolactam (nylon 6). The battery is dried, injected with electrolyte, and then encapsulated, allowed to stand, formed, and volume-adjusted to obtain a soft-pack battery.

[0097] The positive electrode active material can be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate; the negative electrode active material can be selected from one or more negative electrode active main materials, such as artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0098] (6) Battery pack assembly: Multiple pouch batteries are connected in series or parallel and then installed in a housing. The housing includes side panels and fasteners. The side panels include inner side panels and outer side panels. The fasteners are welded to the outer side panels through welding parts to assemble a pouch battery pack.

[0099] The preparation of other embodiments and comparative battery packs is the same as in Embodiment 1, and the changes in each parameter are shown in Table 1.

[0100] Table 1

[0101] The testing method is as follows: Test method for whether the outer insulation layer of the housing has failed: Following the battery pack preparation method described above, for each embodiment and comparative example, corresponding pouch cells were prepared. Twelve pouch cells were connected in series to form a battery pack, with all other test conditions remaining consistent. The outer casing was disassembled, and the maximum depth d of the welded portion along the first direction X was measured. The pouch cell casing opposite the welded portion was observed. If the outer insulation layer 13 showed no change in color or shape, it was considered good; if the outer insulation layer 13 was locally yellowed but no other abnormalities appeared, it was considered acceptable; if the surface was discolored and carbonized, or delamination occurred (i.e., the outer insulation layer 13 detached from the interface of the intermediate metal layer 14), or surface cracks appeared, or bubbles or bulges appeared, it was judged as unacceptable.

[0102] Test method for whether the fastener and the outer side plate are detached from the weld: Following the battery pack fabrication method described above, corresponding pouch cells were prepared for each embodiment and comparative example. Twelve pouch cells were connected in series to form a battery pack, with all other test conditions remaining consistent. The battery pack was mounted on a vibration table according to GB / T2423.43. The testing process was conducted according to GB / T2423.56. Random and fixed-frequency vibration loads were applied in each direction, preferably in the following order: random z-axis, fixed-frequency z-axis, random y-axis, fixed-frequency y-axis, random x-axis, fixed-frequency x-axis (the line connecting the front and rear of the battery pack is the x-axis direction, and another horizontal direction perpendicular to the x-axis is the y-axis direction). The vibration frequency, power spectral density (PSD), and vibration time are shown in Table 2 below. After vibration, it was observed whether the weld between the fixing component and the outer side plate had detached.

[0103] Table 2

[0104] As shown in Table 1, when the B / K formula value is in the range of 15.2μm to 350μm in Examples 1-12, the outer insulation layer of the casing does not fail, and the welding of the fastener to the outer side plate does not detach. Thus, the manufacturing reliability and safety of the battery pack are significantly improved.

[0105] In Comparative Example 1, the B / K ratio is greater than 350 μm. If K is too small (shallow welding depth) or B is too large (thick outer insulation layer 13), the fastener will detach from the outer panel. Therefore, if B / K is too large, the welding strength cannot be guaranteed. In Comparative Example 2, the B / K ratio is less than 15.2 μm. If K is too large (relatively deep welding depth) or B is too small (thin outer insulation layer 13), the outer insulation layer of the casing will fail. Therefore, if B / K is too small, the soft-pack battery casing will be more affected by the welding heat.

[0106] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery pack, characterized in that, include: Multiple pouch batteries (1), each pouch battery (1) includes a housing (10), the housing (10) includes two large surfaces (11) opposite each other along a first direction (X) and two side surfaces (12) opposite each other along a second direction (Z), the multiple pouch batteries (1) are arranged along the first direction (X), the first direction (X) is perpendicular to the second direction (Z); A housing (2) for housing the pouch battery (1), the housing (2) including a side plate (21) and a fastener (22), wherein along the first direction (X), the side plate (21) is disposed opposite to the large surface (11); along the second direction (Z), the fastener (22) is disposed opposite to the side surface (12); the side plate (21) includes an inner side plate (211) and an outer side plate (212), wherein along the first direction (X), the inner side plate (211) is closer to the pouch battery (1) than the outer side plate (212); the fastener (22) The outer side plate (212) is welded by at least one weld (23), which is opposite to the large surface (11); the housing (10) includes an outer insulation layer (13) with a thickness of B μm, and the ratio d / L of the maximum depth d mm of the weld (23) along the first direction (X) to the total thickness L mm of the side plate (21) is K, wherein B / K ranges from 15.2 μm to 350 μm; B μm ranges from 10 μm to 40 μm; and K ranges from 0.1 to 0.

7. The outer side plate (212) has a first area with a rib (27) and a second area without the rib (27). The rib (27) protrudes in the first direction (X) toward the side away from the soft-pack battery (1). The welded part (23) is located in the second area. The inner side plate (211) is connected to the outer side plate (212) where the first area is located by fasteners (24); Along the first direction (X), the distance D1mm between the welded part (23) and the housing (10) ranges from 2.5mm to 20mm.

2. The battery pack according to claim 1, characterized in that, Along the third direction (Y), the welded part (23) is offset from the center of the outer side plate (212) by a size range of 10mm to 75mm, and the third direction (Y), the first direction (X) and the second direction (Z) are perpendicular to each other.

3. The battery pack according to claim 2, characterized in that, Along the third direction (Y), the minimum distance D3mm between the welded part (23) and the edge of the outer side plate (212) ranges from 5mm to 35mm.

4. The battery pack according to claim 1, characterized in that, Along the second direction (Z), the welded part (23) is offset from the center of the soft-pack battery (1), and the offset dimension D4mm ranges from 10mm to 40mm.

5. The battery pack according to claim 4, characterized in that, Along the second direction (Z), the minimum distance D5mm between the welded part (23) and the edge of the outer side plate (212) ranges from 5mm to 35mm.

6. The battery pack according to claim 1, characterized in that, Along the third direction (Y), there are multiple welding parts (23), and the distance between two adjacent welding parts (23) is D6mm, which ranges from 15mm to 60mm. The third direction (Y), the first direction (X), and the second direction (Z) are perpendicular to each other.

7. The battery pack according to claim 1, characterized in that, The projected area of ​​a single welded portion (23) in the first direction (X) is 100 mm. 2 ~3000mm 2 .

8. The battery pack according to claim 1, characterized in that, The fastener (22) is a metal cable tie, and the two ends of the metal cable tie are respectively welded to the two outer plates (212) opposite to each other along the first direction (X).

9. The battery pack according to claim 8, characterized in that, The outer casing (2) also includes a top plate (25) disposed opposite to the metal cable tie along the second direction (Z); Along the second direction (Z), both ends of the metal cable tie are offset from the center of the large surface (11) and are located near the end of the outer side plate (212) away from the top plate (25).

10. The battery pack according to claim 9, characterized in that, The top plate (25) and the inner side plate (211) are integrally formed parts.

11. The battery pack according to claim 9, characterized in that, The outer shell (2) also includes two end plates (26) opposite each other along a third direction (Y), the top plate (25) together with the two side plates (21) and the two end plates (26) form an outer shell (2) with an opening on one side, the third direction (Y), the first direction (X) and the second direction (Z) being perpendicular to each other.

12. The battery pack according to claim 1, characterized in that, Along the first direction (X), the distance between the second region and the inner side plate (211) ranges from 2mm to 8mm.

13. The battery pack according to any one of claims 1-12, characterized in that, The pouch battery (1) group also includes a buffer pad (3), which is provided between the inner side plate (211) and the large surface (11) of the pouch battery (1); and / or, the buffer pad (3) is provided between the large surface (11) of at least two adjacent pouch batteries (1).

14. The battery pack according to claim 13, characterized in that, Along the first direction (X), the sum of the thicknesses of the plurality of buffer pads (3) is greater than or equal to 10 mm.

15. The battery pack according to claim 13, characterized in that, Along the first direction (X), the thickness of a single buffer pad (3) ranges from 1.5 mm to 3 mm, and the ratio of the thickness of a single buffer pad (3) to the thickness of a single soft-pack battery (1) ranges from 0.05 to 0.

2.

16. The battery pack according to claim 13, characterized in that, The thermal conductivity of the buffer pad (3) is 1 W / (m·K); and / or the elastic modulus of the buffer pad (3) is 0.1 MPa to 30 MPa.

17. The battery pack according to any one of claims 1-12, characterized in that, An insulating element is provided between the inner side plate (211) and the outer side plate (212), and the thickness of the insulating element ranges from 1 mm to 5 mm.

18. The battery pack according to any one of claims 1-12, characterized in that, Along the first direction (X), the inner side plate (211) is provided with an insulating layer on the surface facing the pouch battery (1); and / or, the outer casing (2) is a steel casing.

19. An electrical appliance, characterized in that, include: The battery pack as described in any one of claims 1-18.

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