Integrated soft package battery single module starting battery structure and assembling method thereof

Abstract

The application provides a one-piece soft package battery single-module starting battery structure and an assembling method thereof, and relates to the technical field of battery structures. The one-piece soft package battery single-module starting battery structure comprises a battery lower cover, a battery upper cover which is combined with the upper end of the battery lower cover, a cell group which is formed by a plurality of single cells arranged without spacing and is accommodated in the battery lower cover, a BMS main plate which is arranged above the cell group, and the tab of the single cell is connected to the BMS main plate by welding, and an electrode column which is divided into a positive output copper column and a negative output copper column, is welded on the BMS main plate, and extends through the battery upper cover. The BMS main plate, the cell tab and the output copper column are integrally formed by laser welding, the internal wire harness and the plug-in are cancelled, the fault points such as virtual welding and poor contact of the wire harness are eliminated, the insulating sheet is matched with aerogel foam to replace the traditional rigid filling material and the plastic protection piece, the whole process is free of screw locking, and the short circuit hidden danger caused by screw loosening is eliminated.

Description

Technical Field

[0001] This invention relates to the field of battery structure technology, specifically to an integrated soft-pack battery single-module starter battery structure and its assembly method. Background Technology

[0002] Currently, pouch batteries are increasingly widely used in the field of starting power supplies due to their advantages such as high energy density, good safety performance, and flexible design. In the assembly process of pouch battery modules, the connection between the cell tabs is usually completed using resistance welding. Resistance welding heats the workpiece to a molten or plastic state through the resistance heat effect generated by the current flowing through the contact surface and adjacent areas, thus welding the tabs to the connectors.

[0003] However, the welding quality of resistance welding is affected by multiple factors, including electrode pressure, welding current, and energizing time, resulting in a narrow process window and poor stability. Defects such as oxidation and incomplete welds are prone to occur at the weld joints. During long-term charge-discharge cycles, the contact resistance gradually increases, leading to intensified localized heating, which in turn triggers a vicious cycle of further oxidation and continuously rising contact resistance. This problem is currently the most significant technical obstacle faced by soft-pack starter battery modules in the assembly stage, directly impacting the battery pack's conductivity stability, lifespan, and safety. Summary of the Invention

[0004] Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides an integrated soft-pack battery single-module starting battery structure and its assembly method, which solves the problems of unstable welding quality and easy oxidation and poor soldering of existing soft-pack battery modules when using resistance welding for tab connection.

[0006] Technical solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: an integrated soft-pack battery single-module starting battery structure, comprising:

[0008] Battery bottom cover;

[0009] The battery top cover fits over the upper end of the battery bottom cover;

[0010] The battery cell assembly consists of multiple individual cells arranged without gaps and housed inside the lower cover of the battery.

[0011] The BMS motherboard is located above the battery cell assembly, and the tabs of the individual battery cells are soldered to the BMS motherboard.

[0012] The electrode posts are divided into positive output copper posts and negative output copper posts, which are respectively soldered to the BMS main board and extend through the battery cover;

[0013] Insulating sheets are attached to the left and right sides of the battery cell assembly, respectively.

[0014] Preferably, the upper battery cover and the lower battery cover are sealed and fixed by ultrasonic welding.

[0015] Preferably, the electrode tabs are connected to the BMS mainboard, and the electrode posts are connected to the BMS mainboard by laser welding.

[0016] Preferably, the spaces between adjacent single cells are filled with aerogel foam composite material.

[0017] Preferably, the BMS motherboard has a tab soldering groove, and the tab passes through the tab soldering groove to be soldered to the BMS motherboard.

[0018] Preferably, the ports of the electrode posts are sealed with sealant, and the sealant used for the positive output copper posts and the negative output copper posts is of different colors.

[0019] Preferably, the electrode post has a through hole on its body.

[0020] Preferably, the electrode post is internally threaded with a fixing bolt.

[0021] An assembly method for an integrated soft-pack battery single-module starter battery structure includes the following steps:

[0022] S1. Arrange multiple single cells without gaps to form a cell group;

[0023] S2. Attach insulating sheets to the left and right sides of the battery cell assembly respectively;

[0024] S3. Place the BMS mainboard above the battery cell assembly, and solder the tabs of the single battery cell to the BMS mainboard;

[0025] S4. Solder the electrode posts to the BMS mainboard respectively;

[0026] S5. Vertically place the assembled module into the lower battery cover;

[0027] S6. Place the upper battery cover over the upper end of the lower battery cover and seal it in place.

[0028] Preferably, the upper battery cover and the lower battery cover are sealed and fixed by ultrasonic welding.

[0029] Beneficial effects

[0030] This invention provides an integrated soft-pack battery single-module starting battery structure and its assembly method. It has the following beneficial effects:

[0031] 1. This invention provides an integrated soft-pack battery single-module starting battery structure and its assembly method. The BMS mainboard is directly soldered to the battery tabs, and the positive and negative output copper pillars are directly soldered to the BMS mainboard, forming an integrated structure for the input and output ends. The module has no internal plug-ins, no wire harnesses, and no ribbon cables, eliminating the wire harness connection between the BMS and the battery cells in traditional modules. The elimination of the wire harness connection means eliminating frequent after-sales failure points such as poor soldering, poor terminal contact, and wire harness wear.

[0032] 2. This invention provides an integrated soft-pack battery single-module starting battery structure and its assembly method. It uses insulating sheets to replace traditional multi-layered plastic protective components, and aerogel foam composite material replaces rigid fillers such as epoxy resin boards or PC materials between the battery cells. The aerogel foam composite material has compression resilience, which can absorb the expansion mechanical energy generated during the charging and discharging process of the battery cells and release internal stress, preventing damage to the battery cells due to compression. Simultaneously, its low thermal conductivity can form a thermal barrier between adjacent battery cells, preventing the rapid diffusion of heat to surrounding battery cells after thermal runaway of a single battery cell. The entire process is screwless, eliminating safety hazards such as short circuits and leakage caused by loose or detached metal screws. Attached Figure Description

[0033] Figure 1 This is an isometric view of the present invention;

[0034] Figure 2 This is an exploded view of the present invention.

[0035] The components include: 1. Battery top cover; 2. Electrode post; 3. Fixing bolt; 4. BMS main board; 5. Insulating sheet; 6. Single cell; 7. Battery bottom cover. Detailed Implementation

[0036] 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, and 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.

[0037] Example 1

[0038] This embodiment provides an integrated soft-pack battery single-module starter battery structure.

[0039] like Figure 1 and 2As shown, the lower battery cover 7 is a rectangular shell structure with an open top, integrally injection molded from insulating material. The internal dimensions of the lower battery cover 7 match the external contour of the battery cell assembly. The upper battery cover 1 is fitted onto the upper opening of the lower battery cover 7. The upper battery cover 1 and the lower battery cover 7 are sealed and fixed together by ultrasonic welding, with a welding frequency of 20kHz, welding pressure of 0.3~0.5MPa, welding time of 0.5~1.0s, and amplitude of 30~40μm.

[0040] The battery cell assembly consists of multiple individual cells 6 arranged without spacing and housed inside the battery lower cover 7. No rigid spacers are provided between the individual cells 6; the surfaces of adjacent cells 6 are directly opposite each other. In this embodiment, the nominal voltage of each cell 6 is 3.7V and the capacity is 20Ah. Four individual cells 6 are connected in series to form a starting battery module with a nominal voltage of 14.8V and a capacity of 20Ah. In other embodiments, multiple individual cells 6 can also be connected in parallel or in a series-parallel combination, depending on actual needs.

[0041] The BMS mainboard 4 is located above the battery cell assembly. The BMS mainboard 4 is a printed circuit board that integrates the control circuitry, sampling circuitry, and protection circuitry of the battery management system. The BMS mainboard 4 has tab soldering slots that extend through its surface, with their positions corresponding to the tab extension positions of each individual battery cell 6. The positive and negative tabs of each individual battery cell 6 extend from their respective tab soldering slots and are then soldered to pads on the BMS mainboard 4.

[0042] It is important to note that the welding between the electrode tabs and the BMS motherboard 4 is performed using laser welding. The laser power is 2000W–4000W, the welding speed is 50–60mm / s, the spot diameter is 1.0–3.0mm, the defocusing amount is set to negative defocusing (-1 to -3mm), and nitrogen gas is used as the shielding gas (flow rate 15–20L / min). For copper and aluminum electrode tabs, due to their different laser absorption rates, offset spot welding or oscillating welding methods can be used to improve the flowability of the molten pool. The heat-affected zone of laser welding is controlled within 0.5mm, and the penetration depth control accuracy reaches ±0.1mm.

[0043] Electrode post 2 consists of a positive output copper post and a negative output copper post. The positive and negative output copper posts are soldered to the corresponding output pads on the BMS mainboard 4, extending through the battery cover 1 and above its upper surface. The soldering between electrode post 2 and the BMS mainboard 4 is also done using laser welding. Electrode post 2 is made of copper with a nickel-plated surface. A through-hole, a radially penetrating circular hole, is provided on the electrode post 2 for connecting the terminals of an external load. A threaded hole is provided inside electrode post 2, into which a fixing bolt 3 is threaded to secure the terminals of the external wires to the upper surface of electrode post 2.

[0044] Insulating sheets 5 are attached to the left and right sides of the battery cell assembly. The insulating sheets 5 are made of polyimide film with a thickness of 0.1–0.3 mm. The insulating sheets 5 are fixed to the surface of the outermost single battery cell 6 of the battery cell assembly using double-sided tape. The coverage area of ​​the insulating sheets 5 is larger than the side surface area of ​​the single battery cell 6, with its upper edge protruding 5–10 mm above the upper surface of the battery cell assembly and its lower edge 5–10 mm below the lower surface of the battery cell assembly.

[0045] Example 2

[0046] The difference between this embodiment and embodiment 1 is that an aerogel foam composite material is provided between adjacent single cells 6.

[0047] Aerogel foam composite material is filled in the gap between two adjacent single battery cells 6, and its thickness is 2% to 3% of the thickness of a single battery cell 6. The density of the aerogel foam composite material is 40 kg / m³, the thermal conductivity is 0.024 to 0.030 W / (m·K), the buffer compression ratio is greater than 75%, the permanent deformation rate is less than 10%, and the operating temperature range is -80℃ to 260℃.

[0048] It is important to note that pouch cells undergo periodic expansion and contraction in the thickness direction during charge-discharge cycles. Experimental data shows that the thickness expansion rate of pouch cells under 1C charge-discharge conditions is approximately 3%–8%, and the cumulative irreversible thickness increase can reach 2%–5% with increasing cycle count. Aerogel foam composite materials utilize the compression resilience of their three-dimensional porous nano-insulation structure to absorb mechanical energy and release internal stress during cell expansion, and to rebound and reset during cell contraction. The compressive stress of the aerogel foam composite material is controlled within the range of 0.2–0.8 MPa. Simultaneously, its low thermal conductivity can form a thermal barrier layer between adjacent cells, reducing the lateral heat transfer rate by more than 90% when a single cell experiences thermal runaway.

[0049] Example 3

[0050] The difference between this embodiment and Embodiment 1 or Embodiment 2 is that the port of electrode post 2 is sealed with sealant.

[0051] A potting cavity is provided at the position where the positive and negative output copper pillars penetrate the battery cover 1. The potting cavity has an annular groove structure and surrounds the root of the electrode pillars 2. The potting cavity of the positive output copper pillar is filled with red sealant, and the potting cavity of the negative output copper pillar is filled with black sealant. The sealant is a two-component epoxy resin potting compound, mixed at a mass ratio of A:B=1:1 and then poured in, cured at room temperature for 24 hours. After curing, the sealant forms an elastic sealing layer with a waterproof rating of IP67.

[0052] Example 4

[0053] This embodiment provides an assembly method for an integrated soft-pack battery single-module starter battery structure, including the following steps:

[0054] Step 1: Arrange multiple single cells 6 without gaps to form a cell group. When arranging, the tabs of each single cell 6 face the same direction.

[0055] Step 2: Attach insulating sheets 5 to the left and right sides of the battery cell assembly. The insulating sheets 5 are attached to the surface of the outermost single battery cell 6 using double-sided tape.

[0056] Step 3: Place the BMS motherboard 4 above the battery cell assembly, so that the tabs of each individual battery cell 6 pass through the corresponding tab soldering slots on the BMS motherboard 4. Adjust the position of the BMS motherboard 4 to align its relative position with the battery cell assembly, and then perform laser soldering between the tabs and the solder pads on the BMS motherboard 4.

[0057] Step 4: Solder the positive output copper pillar and the negative output copper pillar to the corresponding output pads on the BMS motherboard 4.

[0058] Step 5: Vertically place the assembled module from Steps 1 to 4 into the lower battery cover 7, keeping the module vertical during placement.

[0059] Step 6: Cover the upper battery cover 1 onto the upper end of the lower battery cover 7, so that the electrode post 2 extends through the corresponding through hole on the upper battery cover 1 to above the upper end surface of the upper battery cover 1. Then, seal and fix the upper battery cover 1 and the lower battery cover 7 by ultrasonic welding.

[0060] Step 7: Fill the ports of electrode post 2 with sealant. Fill the positive output copper post with red sealant and the negative output copper post with black sealant. After filling, let it stand to cure.

[0061] No metal screws are used as internal fasteners for the module during the entire assembly process. The battery top cover 1 and battery bottom cover 7 are permanently sealed and fixed together via ultrasonic welding. Electrical connections and mechanical fixation are achieved between the battery cell assembly and the BMS mainboard 4, and between the BMS mainboard 4 and the electrode posts 2, using laser welding. The insulating sheet 5 is fixed by adhesive bonding.

[0062] Example 5

[0063] The difference between this embodiment and embodiment 4 is that in step six, before the battery top cover 1 is closed on the upper end of the battery bottom cover 7, an O-ring rubber sealing ring is first fitted on the column of the electrode post 2. The sealing ring is set at the penetration position between the electrode post 2 and the battery top cover 1. After the battery top cover 1 is closed, it is compressed to form an auxiliary seal.

[0064] Example 6

[0065] The difference between this embodiment and any of embodiments 1 to 3 is that a groove is provided on the upper surface of the battery cover 1. The groove is a recessed platform structure, and its bottom surface has a through hole for the electrode post 2 to pass through. The depth of the groove is greater than the head thickness of the fixing bolt 3. When the fixing bolt 3 presses the external wiring terminal against the upper surface of the electrode post 2, the head of the fixing bolt 3 is entirely accommodated in the groove and does not exceed the upper surface of the battery cover 1.

[0066] Example 7

[0067] The difference between this embodiment and any of embodiments 1 to 3 is that the inner wall of the battery lower cover 7 is provided with longitudinal reinforcing ribs. The longitudinal reinforcing ribs extend longitudinally along the inner wall of the battery lower cover 7, and their height is lower than the upper end surface of the battery lower cover 7. Since insulating sheets 5 are attached to the left and right sides of the cell assembly, and the thickness of the insulating sheets 5 is 0.1 to 0.3 mm, which is greater than the surface roughness of the longitudinal reinforcing ribs (Ra≤3.2 μm), the longitudinal reinforcing ribs do not directly contact the surface of the single cell 6.

[0068] Example 8

[0069] The difference between this embodiment and any of embodiments 1 to 3 is that the BMS motherboard 4 integrates a temperature sampling circuit and a voltage sampling circuit. The sampling terminals of the temperature sampling circuit are arranged adjacent to the tab soldering groove via wiring on the BMS motherboard 4, and are used to collect the temperature signal at the tab of each individual cell 6. The sampling terminals of the voltage sampling circuit are electrically connected to the pads in the tab soldering groove, and are used to collect the terminal voltage signal of each individual cell 6. The sampling signals from the temperature and voltage sampling circuits are processed by the microcontroller unit on the BMS motherboard 4, and then exchange data with external devices through the electrode posts 2. The entire signal acquisition and transmission process requires no additional temperature or voltage sampling wiring harness.

[0070] Example 9

[0071] The difference between this embodiment and any of embodiments 1 to 3 is that the number of individual cells 6 is 6, arranged in a 2-parallel, 3-series configuration. That is, every 2 individual cells 6 are connected in parallel to form a parallel unit, and the 3 parallel units are connected in series to form a battery module suitable for a 12V starting power supply system. In each parallel unit, the positive tabs of the two individual cells 6 are welded together, and the negative tabs are welded together, and then soldered to the corresponding pads on the BMS mainboard 4.

[0072] Correspondingly, in the assembly method of this embodiment, when arranging the battery cell group, the six single battery cells 6 are divided into three groups, with two single battery cells 6 arranged side by side in each group and the tabs facing the same direction. The positive tabs of the two single battery cells 6 in each group are welded together and the negative tabs are welded together. Then, the three parallel units are arranged in sequence along the thickness direction, and the positive and negative tabs of adjacent parallel units are connected in series and welded. Finally, the lead-out ends of the tabs of each parallel unit are welded to the corresponding pads on the BMS main board 4.

[0073] Example 10

[0074] The difference between this embodiment and any of embodiments 1 to 3 is that the electrode post 2 has four through holes, which are respectively located in the front, back, left, and right directions of the post. The four through holes are evenly distributed in the circumferential direction and spaced 90° apart.

[0075] Working Principle: This starter battery adopts a single-module, single-shell integrated layout. Multiple single cells 6 are arranged without gaps to form a cell group, with aerogel foam composite material filling the spaces between the cells. Insulating sheets 5 are attached to the left and right sides of the cell group for insulation protection. The BMS mainboard 4 is located above the cell group. The cell tabs pass through the tab welding grooves on the BMS mainboard 4 and are directly welded to the BMS mainboard 4, forming an integrated structure for the input end. The positive and negative output copper pillars are welded to the BMS mainboard 4 respectively, forming an integrated structure for the PACK output end. The entire module is vertically placed into the lower battery cover 7, and the upper battery cover 1 is placed on top of the lower battery cover 7 and sealed and fixed by ultrasonic welding. The electrode post 2 extends through the upper battery cover 1, and the through hole on its body is used to connect to the external load. No plastic parts are used for structural fitting and screw fastening throughout the assembly process, and the module's internal structure is fully insulated.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A single-module starting battery structure for an integrated soft-pack battery, characterized in that, include: Battery bottom cover (7); The battery top cover (1) is fitted onto the upper end of the battery bottom cover (7); The battery cell assembly consists of multiple single cells (6) arranged without spacing and housed inside the lower cover (7) of the battery. The BMS motherboard (4) is located above the battery cell assembly, and the tabs of the single battery cell (6) are welded to the BMS motherboard (4). The electrode post (2) is divided into a positive output copper post and a negative output copper post, which are respectively soldered to the BMS main board (4) and extend through the battery cover (1); Insulating sheets (5) are attached to the left and right sides of the battery cell assembly, respectively.

2. The integrated soft-pack battery single-module starting battery structure according to claim 1, characterized in that: The upper battery cover (1) and the lower battery cover (7) are sealed and fixed by ultrasonic welding.

3. The integrated soft-pack battery single-module starting battery structure according to claim 1, characterized in that: The electrode tabs are connected to the BMS mainboard (4), and the electrode posts (2) are connected to the BMS mainboard (4) by laser welding.

4. The integrated soft-pack battery single-module starting battery structure according to claim 1, characterized in that: Aerogel foam composite material is filled between adjacent single cells (6).

5. The integrated soft-pack battery single-module starting battery structure according to claim 1, characterized in that: The BMS motherboard (4) has a tab welding groove, and the tab passes through the tab welding groove to be welded to the BMS motherboard (4).

6. The integrated soft-pack battery single-module starting battery structure according to claim 1, characterized in that: The port of the electrode post (2) is sealed with sealant, and the color of the sealant used to seal the positive output copper post and the negative output copper post is different.

7. The integrated soft-pack battery single-module starting battery structure according to claim 1, characterized in that: The electrode post (2) has a through hole on its body.

8. The integrated soft-pack battery single-module starting battery structure according to claim 1, characterized in that: The electrode post (2) is internally threaded with a fixing bolt (3).

9. An assembly method for an integrated soft-pack battery single-module starter battery structure as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Arrange multiple single cells (6) without gaps to form a cell group; S2. Attach insulating sheets (5) to the left and right sides of the battery cell assembly respectively; S3. Place the BMS main board (4) above the battery cell assembly and solder the tabs of the single battery cell (6) to the BMS main board (4); S4. Solder the electrode posts (2) onto the BMS mainboard (4) respectively; S5. Vertically place the assembled module into the battery cover (7); S6. Cover the upper battery cover (1) onto the upper end of the lower battery cover (7) and seal it in place.

10. The assembly method of the integrated soft-pack battery single-module starting battery structure according to claim 9, characterized in that: The upper battery cover (1) and the lower battery cover (7) are sealed and fixed by ultrasonic welding.

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