Fire prevention structure for pouch lithium battery packs

Abstract

To provide fire spread prevention structure for a pouch lithium battery pack capable of solving a safety issue that is fire spread due to thermal runaway.SOLUTION: Fire spread prevention structure includes a plurality of single cells, the plurality of single cells are mounted in a battery housing. A heat insulation material is attached to between adjacent single cells, a glass fiber cloth for protecting the single cells in an outermost layer is attached to the surface of the two single cells in the outermost layer. An aluminum tab for a positive electrode of the single cell is subjected to nickel surface treatment, and the aluminum tab for the positive electrode after being subjected to the nickel surface treatment is folded in a recess of the single cell and fixed with an adhesive. An EVA form is attached to the recess of the single cell, and the aluminum tab for the positive electrode and a tab for a negative electrode are attached to the EVA form. A printing wiring board is provided above the plurality of single cells, and the aluminum tab for the positive electrode and the tab for the negative electrode pass through the wiring board.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of pouch lithium battery packs, and more particularly to a fire prevention structure for pouch lithium battery packs. [Background technology]

[0002] Pouch lithium batteries are being applied to electric assist bicycles and electric scooters, but battery modules currently on the market are generally made up of individual cells stacked one on top of another, and there is no structure designed between the individual cells in the battery module to prevent the spread of fire due to thermal runaway. This has resulted in safety issues such as explosions and fires caused by thermal runaway in pouch lithium battery packs, which has hindered the mass use of pouch lithium batteries in the electric bicycle market. Against this background, this has become a major issue that automobile manufacturers and battery companies need to resolve urgently. Therefore, in order to solve the above problems in the prior art, it is urgent to provide a new fire prevention structure for a pouch lithium battery pack. Summary of the Invention [Problem to be solved by the invention]

[0003] SUMMARY OF THE INVENTION The present invention aims to provide a fire prevention structure for a pouch lithium polymer battery pack in order to solve the safety problem of fire spread due to thermal runaway of the pouch lithium polymer battery pack module. [Means for solving the problem]

[0004] In order to achieve the above object, the present invention provides the following solution. The present invention provides a fire prevention structure for a pouch lithium battery pack, the pouch lithium battery pack including a plurality of unit cells, the plurality of unit cells being mounted in a battery housing. Heat insulating material is attached between adjacent unit cells, and glass fiber cloth for protecting the unit cells in the outermost layer is attached to the surfaces of the two unit cells in the outermost layer. The aluminum tabs for the positive electrodes of the unit cells are nickel surface treated, and the nickel surface treated aluminum tabs for the positive electrodes are attached to the unit cells. groove The battery is folded back and fixed with adhesive. groove An EVA foam is attached to the battery, and the aluminum tabs for the positive electrodes and the aluminum tabs for the negative electrodes of the cells are attached to the EVA foam. A printed wiring board is provided above the multiple cells, and the aluminum tabs for the positive electrodes and the aluminum tabs for the negative electrodes of the cells pass through the printed wiring board.

[0005] Preferably, the positive and negative leads of the power source of the pouch lithium battery pack are connected by terminals of a wiring board, and fixed in a wiring duct in the battery plastic frame. Preferably, the heat insulating material has dimensions larger than the dimensions of the unit cells, and flame-retardant double-sided tape is attached to both sides of the heat insulating material.

[0006] Preferably, a portion of the pouch lithium battery pack formed by the cell and the insulating material is in contact with the battery housing at a position where the head and tail of the pouch lithium battery pack contact the battery housing. groove is filled with a thermally conductive silicone gel and tightly adhered to the battery housing.

[0007] Preferably, the battery housing is an openwork battery plastic frame, the battery plastic frame includes a left battery plastic frame and a right battery plastic frame, and the left battery plastic frame and the right battery plastic frame are connected by a buckle.

[0008] Preferably, the battery housing is a sealed plastic housing, and the sealed plastic housing includes a left sealed plastic housing and a right sealed plastic housing, and the left sealed plastic housing and the right sealed plastic housing are connected by a buckle, and a sealing groove is provided at the connection portion.

[0009] A thermally conductive silicone gel is applied to the periphery of the pouch lithium battery pack and the nickel block of the printed wiring board, and a thermally conductive silicone gel is applied to the inner wall of the plastic housing. [Effects of the Invention]

[0010] Compared with the prior art, the present invention has the following technical advantages:

[0011] This invention solves the safety issue of fire spread due to thermal runaway in pouch lithium polymer battery pack modules. It employs an innovative design instead of the traditional stacking method used in battery module design, using a cell-insulator-cell configuration. The cell tabs are connected in series or parallel via spot welding via a printed wiring board, and the entire battery pack is fixed in place by applying adhesive to the battery housing. If a cell experiences thermal runaway and causes an explosion or fire, the heat is insulated and prevented from spreading, preventing thermal runaway in adjacent cells and avoiding the risk of fire or ignition. During normal operation, the cells in the battery pack do not conduct heat to each other, ensuring uniform temperature distribution, improving the overall performance of the battery pack and extending its service life. [Brief explanation of the drawings]

[0012] In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly introduced below. Of course, the drawings described below are only the embodiments of the present invention, and those skilled in the art can think of other drawings based on these drawings without any creative efforts.

[0013] [Figure 1] 1 is a schematic diagram of a fire spread prevention structure of a pouch lithium battery pack according to a first embodiment. [Figure 2] 3 is a schematic diagram showing how the positive and negative electrode tabs of the cell according to Example 1 are bent into an L shape. FIG. [Figure 3] FIG. 2 is a schematic diagram showing the case where an aluminum tab for a positive electrode of a single battery according to Example 1 is subjected to nickel surface treatment and fixed with an adhesive. [Figure 4] 1 is a schematic diagram showing the application of thermally conductive silicone gel to a pouch lithium battery pack according to Example 1. FIG. [Figure 5] 1 is a schematic diagram of a pouch lithium battery pack according to Example 1 when left and right plastic frame structures are attached. [Figure 6] 1 is a structural schematic diagram of the pouch lithium battery pack according to Example 1 when left and right plastic frames are attached and the buckles of the left and right plastic frames are fastened. [Figure 7] 1 is a schematic diagram of the bottom structure when left and right plastic frames are attached to the pouch lithium battery pack according to Example 1. FIG. [Figure 8] 1 is a schematic diagram of the structure of a printed wiring board according to a first embodiment. [Figure 9] 1 is a schematic diagram of the external structure when a battery plastic frame according to Example 1 is attached. [Figure 10] 1 is a schematic diagram of a power supply lead terminal when the positive and negative leads of the battery pack according to Example 1 are fixed in a wiring duct in a plastic frame and connected to a printed wiring board. FIG. [Figure 11] 3 is a schematic diagram showing a case where an insulating sheet is attached to the upper surface of a printed wiring board according to the first embodiment. FIG. [Figure 12] 1 is a first schematic diagram of a pouch lithium battery pack after undergoing a fire spread test according to the present invention; FIG. [Figure 13] FIG. 2 is a second schematic diagram of a pouch lithium battery pack according to the present invention after a fire spread test. [Figure 14] FIG. 10 is a third schematic diagram of a pouch lithium battery pack according to the present invention after a fire spread test. [Figure 15] Cross section AA of Figure 14. [Figure 16]10 is a schematic diagram of a fire spread prevention structure of a pouch lithium battery pack according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] The following clearly and completely describes the technical solutions of the embodiments of the present invention in combination with the drawings of the embodiments of the present invention, and it should be understood that the described embodiments are merely examples of the present invention and do not represent all the embodiments. Based on the embodiments of the present invention, all other embodiments that can be conceived by those skilled in the art without any creative effort fall within the technical scope of the present invention.

[0015] In order to clarify and understand the above objects, features and advantages of the present invention, the present invention will be described in more detail below in combination with the drawings and embodiments of the invention. Example 1

[0016] As shown in Figure 1, this embodiment provides a fire prevention structure for a pouch lithium battery pack. Here, the pouch lithium battery pack module is composed of a plurality of unit cells connected in series or parallel. However, the embodiment of the present invention is not limited to the number of unit cells connected in series. The pouch lithium battery pack is mounted in a battery housing.

[0017] In this embodiment, the battery housing is an openwork plastic battery frame, which includes a left battery plastic frame and a right battery plastic frame, connected by a buckle. Insulating material is attached between each cell. The insulating material (thermal conductivity 0.02 W / mk) provides ultra-high insulation, flame retardancy, and impact resistance. The dimensions of the insulating material are designed to be slightly larger than the dimensions of the cells (L1 > L2, D1 = D2), and the insulating material is attached between all cells in the battery module in this manner. See Figures 13 and 15.

[0018] In this example, flame-retardant double-sided tape is attached to both sides of the insulating material to bond and secure the insulating material to the cells, and glass fiber cloth is attached to the surface of the first and last cells in the outermost layer to protect the cells in the outermost layer (see Figure 1).

[0019] In this embodiment, the aluminum tab for the positive electrode of each cell is subjected to nickel surface treatment, and the nickel surface-treated tab is sealed. groove The battery is folded over at the end and fixed with adhesive. groove EVA foam is attached to this part for cushioning, isolation, and insulation. The positive and negative electrode tabs are shaped into an L and attached to the EVA foam to prevent vibration and dropping during battery pack use, and to serve as cushioning, vibration damping, and to prevent the tabs from breaking. See Figure 2-3.

[0020] In this embodiment, as shown in Figure 8, a printed wiring board is installed above the cells, each cell tab passes through the printed wiring board, nickel blocks are attached to the printed wiring board, and the batteries are connected in series or parallel by spot welding to form a battery module. The printed wiring board is provided with heat dissipation vents to conduct heat generated by the combustion of a battery experiencing thermal runaway to the outside and reduce heat accumulation. Here, two nickel blocks are installed for the positive and negative electrodes of each cell, and the number of nickel blocks is determined by the number of batteries connected in series or parallel. The nickel blocks facilitate electrical connection by spot welding the positive and negative electrode tabs of the cells and also allow heat from inside the cells to be conducted to the nickel blocks and the printed wiring board, thereby providing a consistent heat dissipation and securing the module structure.

[0021] In this embodiment, as shown in FIG. 11, an insulating sheet is further included, which is attached to the upper surface of the printed wiring board and is used to insulate the battery pack and prevent short circuits.

[0022] In this embodiment, the positive and negative leads of the battery pack power supply are connected by the terminals of the wiring board and fixed in the battery plastic frame wiring duct, preventing the lead wires from falling off or the connecting terminals from cracking due to vibration or dropping. groove The battery module is filled with thermally conductive silicone gel (see Figure 4) and tightly bonded to a thermally conductive plastic battery frame with a thermal conductivity of 1.8-10 W / mk and flame retardancy of UL94-V0. The battery plastic frame has two parts, which are fastened together with a buckle and serve to reinforce the battery module and dissipate heat.

[0023] This embodiment is an improvement on the basis of the first embodiment, and the improvements are as follows: the battery housing is a sealed plastic housing, and a fully sealed structure is used, the sealed plastic housing includes a left sealed plastic housing and a right sealed plastic housing, and the left sealed plastic housing and the right sealed plastic housing are connected by a buckle, and a sealing groove is provided and fixed with adhesive.

[0024] The battery housing has heat-dissipating ribs evenly distributed on the outside, and a 10mm diameter ventilation hole is drilled at the top of the battery housing (above the printed wiring board), and a 20mm diameter waterproof and breathable membrane is attached. When the battery pack is operating normally and dissipating heat, the thermally expanded air can escape through the waterproof and breathable membrane, preventing moist air from entering the housing. The waterproof level reaches IP67. It can also function as a safety relief valve in the event of abnormal thermal runaway in the battery.

[0025] A thermally conductive silicone gel is evenly applied to the periphery of the pouch lithium battery pack and the nickel block of the printed wiring board, and a thermally conductive silicone gel is also applied to the inner wall of the sealed plastic housing, which serves to adhere and fix the pack and also to conduct heat to the housing and release the heat to the outside.

[0026] In this invention, fully charged battery pack modules are placed in a case or housing, and one of them is pierced with a needle as an overcharged cell to simulate combustion or smoke emission due to battery thermal runaway. No fire spread to adjacent cells, and as shown in Figures 12-15, the appearance of the adjacent cells is neat, the battery voltage is 4.15V, and the maximum temperature of the adjacent cells is much lower than the thermal runaway temperature that the cells can tolerate. The housing material can be modified thermally conductive engineering plastics such as PA6 or PC, with thermal conductivity K=1.8~10W / mk and flame retardancy UL94-V0. The heat dissipation rib material is the above-mentioned material, which is designed as a heat dissipation rib in the plastic housing structure and is formed by injection molding, which can improve the strength of the plastic housing and the function of the heat dissipation.

[0027] In actual application of the product, if any cell in the battery module experiences thermal runaway and catches fire, the risk of the fire spreading to more adjacent cells, exploding, catching fire, and causing a fire can be avoided, the problem of heat conduction between the cells can be resolved, and heat accumulation can be reduced, thus greatly improving the safety of the battery pack, reducing safety risks and preventing damage to personnel and property. The test has produced good results, which are practical and creative.

[0028] Although the present invention has been described using specific examples to explain the principles and embodiments of the present invention, the description of the above examples is merely used to understand the method of the present invention and its core idea. At the same time, those skilled in the art will recognize that the form of implementing the invention and the scope of application can all be modified based on the idea of ​​the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for manufacturing a pouch lithium battery pack, comprising: The pouch lithium battery pack includes a plurality of cells, the plurality of cells being mounted within a battery housing; A heat insulating material is attached between adjacent cells, a glass fiber cloth for protecting the unit cells in the outermost layer is attached to the surfaces of the two unit cells in the outermost layer; a printed wiring board is provided above the plurality of unit cells; The positive electrode aluminum tab and the negative electrode tab of the battery pass through the printed wiring board, a step of performing nickel surface treatment on the positive electrode of the battery cell and applying an adhesive thereto;

2. The positive electrode aluminum tab and the negative electrode tab of the unit cell are formed into an L shape, 2. The method of claim 1, wherein the adhesive is applied to EVA foam.

3. 2. The manufacturing method according to claim 1, wherein a nickel block is attached to the printed wiring board.

4. 4. The manufacturing method according to claim 3, wherein the positive electrode aluminum tab and the negative electrode tab of the unit cell are connected to the printed wiring board by spot welding.

5. 5. The manufacturing method according to claim 4, wherein the printed wiring board is provided with a heat dissipation vent hole, and an insulating sheet is attached to the upper surface of the printed wiring board.

6. The positive and negative leads of the power source of the pouch lithium battery pack are connected by terminals of a printed wiring board; 2. The manufacturing method according to claim 1, wherein the battery is fixed in a wiring duct in a plastic frame.

7. The manufacturing method described in claim 1, characterized in that fire-retardant double-sided tape is attached to both sides of the insulation material.

8. 2. The manufacturing method according to claim 1, wherein a thermally conductive silicone gel is filled into a groove formed by the cell and the insulating material at the position where the head and tail of the pouch lithium battery pack contact the battery housing, and the thermally conductive silicone gel is tightly adhered to the battery housing.

9. The battery housing is an openwork battery plastic frame, and the battery plastic frame includes a left battery plastic frame and a right battery plastic frame; The manufacturing method according to any one of claims 1 to 8, wherein the left battery plastic frame and the right battery plastic frame are connected by a buckle.

10. the battery housing is a sealed plastic housing; the sealed plastic housing includes a left sealed plastic housing and a right sealed plastic housing; The left and right closed plastic housings are connected by a buckle, and a sealing groove is provided at the connection portion; A thermally conductive silicone gel is applied to the periphery of the pouch lithium battery pack and the nickel block of the printed wiring board, and a thermally conductive silicone gel is applied to the inner wall of the plastic housing; The manufacturing method according to any one of claims 1 to 8, characterized in that heat dissipation ribs are uniformly distributed on the outside of the battery housing, ventilation holes are drilled at the top of the battery housing, and a waterproof ventilation membrane is provided on the ventilation holes.

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