Soft package fixing and pressurizing structure and high-expansion battery module

Abstract

The invention discloses a soft package fixing and pressurizing structure and a high-expansion battery module, the soft package fixing and pressurizing structure comprises an entanglement, the entanglement is wound along the length direction of a cell stack and wraps the cell stack, and the entanglement is a flexible material. The high-strength fiber rope and the high polymer material fiber cloth are used for replacing metal structural parts such as stainless steel or aluminum alloy to be wound and wrapped on the outer side of the high-expansion battery module, so that the high-expansion battery module has good mechanical strength and light weight characteristics, can bear stress and deformation in the battery circulation process, and does not generate the phenomenon that the module structure and the appearance are damaged and cracked; the service life of the battery is prolonged, the stability of the battery under different environmental conditions is ensured, and the safety and the energy density of the battery module are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, in particular to a soft-pack fixed pressurization structure and a high-expansion battery module. Background Art

[0002] With the demand for high-energy-density batteries in the low-altitude economy and electric vehicles, silicon-based anode and lithium-metal anode batteries have received extensive attention. However, such batteries all have a common problem, high expansibility. During the cycling process of the battery, the thickness of the battery increases significantly. After the batteries are grouped, the large expansion stress brought about by this reaches even more than several MPa at the end of the cycle. If such a large expansion force cannot be released, it will squeeze and break the aluminum-plastic film and the battery case, resulting in battery failure and even triggering safety risks. Secondly, whether it is a silicon-carbon or lithium-metal solid-state battery, it usually needs to work under a certain pressure to ensure the contact between the electrodes and the electrolyte, so as to improve the cycle life and energy density of the battery module.

[0003] In the design of battery modules, stainless steel or aluminum alloy is traditionally widely used as the main material for the module fixing and bearing structure. These metal materials have good mechanical strength and durability, but at the same time they also have the following deficiencies: The metal materials are relatively heavy, resulting in a relatively large overall mass of the module, which limits the further improvement of the energy density of the module. During the cycling process of the battery, due to the effects of thermal expansion and volume expansion, the metal components are prone to generate excessive internal stress, resulting in module deformation or even structural damage. Metal materials usually require complex processing techniques (such as stamping, welding, etc.), increasing the manufacturing cost and process difficulty.

[0004] In order to increase the initial pre-tightening force, the methods of fixing with bolts after extrusion or structural welding are usually adopted. Secondly, in order to limit the large expansion force at the end of the cycle of high-expansion batteries, the structural components of the battery module usually adopt high-strength aluminum alloy and steel, which will lead to a decrease in the grouping rate of the battery module, seriously affecting the energy density of the battery module and causing the loss of the high-energy-density advantage of silicon-carbon and lithium-metal anode batteries.

[0005] Therefore, being able to increase a certain pre-tightening force and develop a fixing and pressurizing device for a high-expansion battery module to relieve stress and extend the cycle life of the battery has become a key technical point. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is that: the expansion stress after the batteries are grouped cannot be effectively released by the traditional fixing device.

[0007] The above technical problem is solved by the following technical solution: The present invention provides a soft-pack fixed pressurization structure, which includes a winding member that winds along the length direction of the battery stack and wraps it, and the winding member is a flexible material.

[0008] In a preferred embodiment of the soft-pack fixing and pressing structure of the present invention: the winding material is a high-strength fiber rope, and the high-strength fiber rope includes, but is not limited to, polyester, nylon, ultra-high molecular weight polyethylene rope, aramid rope, carbon fiber rope, and PBO fiber rope. The diameter of the high-strength fiber rope is 0.2 to 3 mm.

[0009] In a preferred embodiment of the soft-pack fixing and pressing structure of the present invention: the winding material is a polymer material fiber cloth, and the polymer material includes, but is not limited to, nylon, carbon fiber, polyester fiber cloth, natural rubber, styrene-butadiene rubber, cis-butadiene rubber, chloroprene rubber, fiber-reinforced composite material, glass fiber-reinforced material, and polytetrafluoroethylene airtight coating. The thickness of the polymer material fiber cloth is 0.2 to 2 mm.

[0010] To solve the above technical problems, the present invention also provides the following technical solution: a high-expansion battery module includes the above-mentioned soft-pack fixing and pressing structure, and the battery cell stack includes a plurality of battery cells stacked in sequence. The tabs of the battery cells are on the same vertical line, and a bus bar is fixedly arranged outside the tabs.

[0011] In a preferred embodiment of the high-expansion battery module of the present invention: a plurality of through grooves are formed on the bus bar, and the through grooves correspond to the tabs one by one.

[0012] In a preferred embodiment of the high-expansion battery module of the present invention: it further includes end plates, which are fixedly arranged on both sides of the battery cell stack. Through holes are formed at the four corners of the end plates for initial pressing and fixing of the battery module, and the winding material is wrapped outside the end plates along a direction perpendicular to the tabs to resist the expansion force of the battery.

[0013] In a preferred embodiment of the high-expansion battery module of the present invention: shrapnel is also arranged between the battery cell stack and the end plates and between the battery cells, and high-viscosity glue is used for fixing between the battery cells and the shrapnel to prevent the battery cell stack from shifting.

[0014] In a preferred embodiment of the high-expansion battery module of the present invention: the width of the end plate is the same as that of the battery cell stack, the length of the end plate is greater than the length of the battery cell stack, and the thickness of the end plate is 2 to 20 mm.

[0015] In a preferred embodiment of the high-expansion battery module of the present invention: the included angle between the end plate and the winding material is set as a chamfer to prevent wear and breakage of the winding material during the cyclic expansion process.

[0016] In a preferred embodiment of the high-expansion battery module of the present invention: the initial pressure of the battery module is controlled by a method of fixing with a pressure bolt. After the winding is fixed, the fixing bolt is removed to bear the expansion force of the battery module.

[0017] The beneficial effects of the present invention are as follows: The present invention uses high-strength fiber ropes to replace traditional metal structural parts such as stainless steel and aluminum alloy, has good mechanical strength and lightweight characteristics, can withstand the stress and deformation during the battery cycle, and will not cause the phenomenon of damage and cracking of the module structure and appearance, which helps to extend the service life of the battery and ensure its stability under different environmental conditions, improving the safety and energy density of the battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention and do not limit the present invention. Among them:

[0019] Figure 1 shows a schematic diagram of a soft-pack fixed pressure structure;

[0020] Figure 2 shows another schematic diagram of a soft-pack fixed pressure structure;

[0021] Figure 3 shows the cycle data of Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below in conjunction with the specific embodiments and the drawings.

[0023] The terms used in the present invention are those general terms that are currently widely used in the art in consideration of the functions of the present invention, but these terms can change according to the intentions of those of ordinary skill in the art, precedents, or new technologies in the art. In addition, specific terms can be selected by the applicant, and in this case, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but based on the meanings of the terms and the overall description of the present invention.

[0024] Example 1

[0025] Referring to Figure 1 , this embodiment provides a high-expansion battery module wrapped with high-strength fiber ropes, including a battery cell stack 1, end plates 2, windings 3, shrapnel 4, and busbars 5.

[0026] Specifically, the winding member 3 is wound along the length direction of the battery cell stack 1 and wraps it. The winding member 3 is a flexible material. The battery cell stack 1 includes a plurality of battery cells 11 stacked in sequence. The tabs 111 of the battery cells 11 are on the same vertical line. A bus bar 5 is fixedly arranged outside the tabs 111. A plurality of through slots 51 are formed in the bus bar 5, and the through slots 51 correspond to the tabs 111 one by one. End plates 2 are fixedly arranged on both sides of the battery cell stack 1. Through holes are formed at the four corners of the end plates 2 for initial pressurization and fixation of the battery module. The winding member 3 is wrapped outside the end plates 2 along the direction perpendicular to the tabs 111 to resist the expansion force of the battery. The tabs 111 pass through the through slots and are bent and then welded to the bus bar 5. The bus bar 5 is fixedly arranged on the left and right sides of the battery cell stack 1.

[0027] Furthermore, shrapnel 4 is arranged between the battery cell stack 1 and the end plates 2 and between the battery cells 11. High-viscosity glue is used to fix between the battery cells 11 and the shrapnel 4 to prevent the deviation of the battery cell stack 1. The width of the end plates 2 is the same as that of the battery cell stack 1. The length of the end plates 2 is greater than the length of the battery cell stack 1. The thickness of the end plates 2 is 2 - 20 mm. The high-performance shrapnel 4 is pasted at intervals between the chips.

[0028] Among them, the winding member is a high-strength fiber rope, and the high-strength fiber rope includes but is not limited to polyester, nylon, ultra-high molecular weight polyethylene rope, aramid rope, carbon fiber rope, and PBO fiber rope. The diameter of the high-strength fiber rope is 0.2 - 3 mm.

[0029] Preferably, the included angle between the end plates 2 and the winding member 3 is set as a chamfer to prevent the wear and breakage of the winding member 3 during the cyclic expansion process.

[0030] It should be noted that the overall thickness of the high-performance shrapnel 4 is 1.9 mm, and its bonding coating is 0.1 mm. The length of the end plates 2 is 310 mm, the width is 100 mm, the thickness is 10 mm, the surface is smooth and flat, and the diameter of the through holes in the end plates is 8 mm. The diameter of the high-strength fiber rope is 1.5 mm.

[0031] After testing, a high-strength fiber rope with a diameter of 1.5 mm can be wound 194 circles in a winding range of 290 mm, that is, a total of 388 roots on both sides, and can withstand a tensile force of about 93.12 tons, that is, withstand an end plate pressure of 29.37 MPa.

[0032] According to the above method, change the diameter of the high-strength fiber rope to 1 mm. After testing, it can be obtained that a high-strength fiber rope with a diameter of 1 mm can be wound 290 circles in a winding range of 290 mm, that is, a total of 580 roots on both sides, and can withstand a tensile force of about 69.6 tons, that is, withstand an end plate pressure of 22.03 MPa.

[0033] According to the above method, the diameter of the high-strength fiber rope is changed to 2.5 mm. The high-strength fiber rope with a diameter of 2.5 mm can be wound 116 times within a winding range of 290 mm, that is, a total of 232 on both sides, and can withstand a tensile force of about 83.52 tons, that is, the end plate pressure is 26.43 MPa.

[0034] In summary, when the diameter of the high-strength fiber rope is 1.5 mm, the maximum end plate pressure value that can be withstood is much greater than the actual expansion pressure of the battery module.

[0035] Example 2

[0036] Refer to Figure 2 , this embodiment provides a high-expansion battery module wrapped with a polymer material fiber cloth.

[0037] Specifically, the battery cell stack 1 is stacked by a plurality of battery cells 11 and the plurality of battery cells 11 are located on the same vertical line. A shrapnel 4 is also arranged between the battery cells 1. The shrapnel 4 fixes the entire battery cell stack 1 through high-viscosity adhesive. The end plates 2 are fixedly arranged on both sides of the battery cell stack 1 and a shrapnel 4 is also fixedly pasted between the end plates 2 and the battery cells 11. The shrapnel 4 fixes the entire battery cell stack 1 to prevent deviation. The winding member 3 is wound and wrapped along the length direction of the battery cell stack 1. Through holes are reserved at the four corners of the end plate 2 for pre-tightening and pressurizing fixation. The initial pressure of the battery module is fixed by passing a pressurizing bolt through the through holes. After the winding member 3 is wound on the end plate 2, the bolt is removed and the winding member 3 is allowed to bear the expansion force of the battery module.

[0038] Furthermore, pole lugs 111 are fixedly arranged at both ends of the battery cell 11. The bus bar 5 is fixedly arranged at both ends of the battery cell stack 1. A plurality of through grooves 51 are formed in the bus bar 5. The through grooves 51 correspond to the pole lugs 111 one by one. After the pole lugs 111 are bent, they can be welded to the bus bar 5 through the through grooves 51.

[0039] Among them, the winding member 3 is a polymer material fiber cloth. The polymer material includes but is not limited to nylon, carbon fiber, polyester fiber cloth, natural rubber, styrene-butadiene rubber, cis-butadiene rubber, chloroprene rubber, fiber-reinforced composite material, glass fiber-reinforced material, polytetrafluoroethylene airtight coating material. The thickness of the polymer material fiber cloth is 0.2 - 2 mm.

[0040] It should be noted that the overall thickness of the high-performance shrapnel is 1.9 mm, its bonding coating is 0.1 mm, the length of the end plate 2 is 310 mm, the width is 100 mm, the thickness is 10 mm, the surface is smooth and flat, the diameter size of the through hole of the end plate is 8 mm, the thickness of the polymer material fiber cloth is 0.35 mm, and the upper and lower carbon fiber end plates 2 are heated and self-welded and wrapped by a heating platform.

[0041] Table 1 Physical property data of the polymer fiber cloth

[0042]

[0043]

[0044] As can be seen from Table 1, the average areal density of the polymer material fiber cloth is 352.2 g / m 2 , while the areal density of steel is 3925 g / m 2 , and the areal density of aluminum is 1350 g / m 2 . The areal density of the polymer material fiber cloth is much smaller than that of steel and aluminum, which helps to reduce the overall weight of the battery module. The polymer fiber cloth has good flexibility, can adapt to the expansion and contraction of the battery module during charge and discharge, and has very high strength, which can effectively resist the expansion force of the battery.

[0045] Comparative Example 1

[0046] According to the method of Example 1, the upper and lower end plates 2 and the high-strength fiber ropes are replaced with a stainless steel shell with a thickness of 30 mm, and different surfaces of the stainless steel shell are connected by welding.

[0047] Cyclic tests were carried out on Example 1 and Comparative Example 1, and the test results are as Figure 3 shown. Due to the stable pressure, the cycle of Example 1 is more stable and the capacity of the battery module is better exerted. Due to the stress concentration at the welded joints of the steel plates, the tensile capacity decreases and the battery module is expanded and opened by the expansion. The structures of the high-strength fiber ropes can all withstand the pressure of the end plate 2 above 29 MPa, which is much greater than the actual expansion pressure of the battery module. The density of the high-strength fiber rope is 1.44 g / cm 3 , which is much smaller than that of steel (about 7.8 g / cm 3 ) and aluminum (about 2.7 g / cm 3 ), and can significantly improve the energy density of the battery.

[0048] It can be seen from Figure 3 that under the same number of cycle times, wrapping the battery module with the end plate 2 and the high-strength fiber ropes makes the capacity of the battery module larger than that of the steel plate, the Coulomb efficiency higher, the capacity loss of the battery smaller, and the battery life longer.

[0049] Finally, it should be pointed out that the methods and devices described in detail above are only examples, and those skilled in the art can modify these examples in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A soft bag fixed pressurized structure, characterized in that: include, A winding (3) is wound along the length direction of the battery core stack (1) and covers the battery core stack (1), and the winding (3) is made of a flexible material.

2. The soft bag fixing and pressurizing structure according to claim 1, characterized in that: The winding (3) is a high-strength fiber rope, which includes but is not limited to polyester, nylon, ultra-high molecular weight polyethylene rope, aramid rope, carbon fiber rope and PBO fiber rope, and the diameter of the high-strength fiber rope is 0.2-3 mm.

3. The soft bag fixing and pressurizing structure according to claim 2, characterized in that: The winding (3) is a polymer fiber cloth, and the polymer material includes but is not limited to nylon, carbon fiber, polyester fiber cloth, natural rubber, styrene-butadiene rubber, butadiene rubber, chloroprene rubber, fiber-reinforced composite material, glass fiber-reinforced material, polytetrafluoroethylene airtight coating, and the thickness of the polymer fiber cloth is 0.2 to 2 mm.

4. A high expansion battery module, characterized in that: It comprises the soft bag fixing and pressurizing structure as claimed in claims 1 to 3, and The battery cell stack (1) comprises a plurality of battery cells (11) stacked in sequence, wherein the pole ears (111) of the battery cells (11) are on the same vertical line, and a bus bar (5) is fixedly arranged on the outer side of the pole ears (111).

5. The high expansion battery module according to claim 4, characterized in that: The busbar (5) is provided with a plurality of through slots (51), and the through slots (51) correspond one-to-one to the pole ears (111).

6. The high expansion battery module according to claim 5, characterized in that: It also includes an end plate (2), which is fixedly arranged on both sides of the battery cell stack (1), and through holes are opened at the four corners of the end plate (2) for initial pressurization and fixation of the battery module, and the winding (3) is wrapped around the outer side of the end plate (2) in a direction perpendicular to the pole ear (111) to resist the expansion force of the battery.

7. The high expansion battery module according to claim 6, characterized in that: Spring sheets (4) are also provided between the battery cell stack (1) and the end plate (2), and between the battery cells (11); the battery cells (11) and the spring sheets (4) are fixed with a high-viscosity adhesive to prevent the battery cell stack (1) from deflecting.

8. The high expansion battery module according to claim 7, characterized in that: The width of the end plate (2) is consistent with that of the battery cell stack (1), the length of the end plate (2) is greater than the length of the battery cell stack (1), and the thickness of the end plate (2) is 2 to 20 mm.

9. The high expansion battery module according to claim 8, characterized in that: The included angle between the end plate (2) and the winding (3) is set as a chamfer to prevent the winding (3) from being worn or broken during the cyclic expansion process.

10. The high expansion battery module according to claim 9, characterized in that: The initial pressure of the battery module is controlled by fixing with pressurized bolts, and after the winding (3) is wound and fixed, the fixing bolts are removed to withstand the expansion force of the battery module.

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