Battery pack design method

Abstract

The invention discloses a battery pack design method, and belongs to the technical field of batteries. According to the design method of the battery pack, lithium iron phosphate is adopted as the positive electrode material of the battery monomers, if c / d is less than or equal to 2.8 Ah / mm and l / d is less than or equal to 6.4, the risk of thermal runaway of the battery monomers is relatively low, and the adjacent battery monomers are not easily affected even if thermal runaway occurs, so that a heat insulation pad is not arranged between any two battery monomers, the space utilization rate of the battery pack is increased, and the service life of the battery pack is prolonged. The cost is reduced; if c / d is greater than 2.8 Ah / mm or l / d is greater than 6.4, the risk of thermal runaway of the battery monomers is increased, and a heat insulation pad is arranged between at least two battery monomers to improve the heat insulation performance between the battery monomers, so that the safety of the battery pack is ensured.

Description

Technical Field

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

[0002] The lithium iron phosphate battery is a new type of lithium-ion battery widely used in fields such as electric vehicles and energy storage systems. The lithium iron phosphate battery has the characteristics of low capacity, good thermal stability, more stable chemical structure, and not easy to decompose. During the charging process, it has a smaller expansion rate and lower heat generation, so it has higher safety and is not prone to thermal runaway.

[0003] In the prior art, heat insulation pads are usually provided between any two adjacent battery cells to prevent heat transfer between the two adjacent battery cells through the heat insulation pads, thereby improving the safety of the lithium iron phosphate battery. The setting of the heat insulation pads not only increases the processing cost, but also results in low space utilization rate inside the battery pack housing. Summary of the Invention

[0004] The purpose of the present invention is to provide a battery pack design method, which can improve the space utilization rate of the battery pack and reduce costs on the premise of ensuring the safety of the battery pack.

[0005] To achieve the above purpose, the following technical solutions are provided:

[0006] A battery pack design method, the battery pack includes a plurality of battery cells stacked along a first direction, the positive electrode material of the battery cell is lithium iron phosphate; the first direction is perpendicular to the large surface of the battery cell;

[0007] The battery pack design method includes the following steps:

[0008] Determine the thickness d of the battery cell along the first direction, the width l of the battery cell along a second direction, and the capacity c of the battery cell; the first direction is perpendicular to the second direction;

[0009] Calculate c / d and l / d;

[0010] Compare the magnitude of c / d with 2.8 Ah / mm, and the magnitude of l / d with 6.4;

[0011] When c / d ≤ 2.8 Ah / mm and l / d ≤ 6.4, no heat insulation pad is provided between any two of the battery cells;

[0012] When c / d > 2.8 Ah / mm or l / d > 6.4, heat insulation pads are provided between at least two of the battery cells.

[0013] Compared with the prior art, the beneficial effects of the present invention:

[0014] In the battery pack design method of the present invention, the cathode material of the battery cell is lithium iron phosphate. If c / d ≤ 2.8 Ah / mm and l / d ≤ 6.4, it indicates that the risk of thermal runaway of the battery cell is relatively low. Even if thermal runaway occurs, it is not easy to affect the adjacent battery cells. Therefore, no heat insulation pad is provided between any two battery cells to improve the space utilization rate of the battery pack and reduce costs. If c / d > 2.8 Ah / mm or l / d > 6.4, it indicates that the risk of thermal runaway of the battery cell increases. A heat insulation pad is provided between at least two battery cells to improve the heat insulation performance between the battery cells, thereby ensuring the safety of the battery pack. Brief Description of the Drawings

[0015] Figure 1 It is a flowchart of the battery pack design method in the embodiment of the present invention. Detailed Description of the Embodiment

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0017] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0018] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0019] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0020] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and defined, the terms "arranged" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In the present invention, unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "under" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0022] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0023] As Figure 1 shown, this embodiment provides a battery pack design method. The battery pack includes a plurality of battery cells stacked along a first direction; the first direction is perpendicular to the large surface of the battery cell. It should be noted that the battery cell includes a plurality of outer surfaces, and the large surface of the battery cell is the largest one among the plurality of outer surfaces of the battery cell.

[0024] Specifically, the battery cell includes an electrode core and a housing. The electrode core is placed inside the housing to isolate it from the outside. The electrode core is the basic unit for storing and releasing electric energy, which is usually composed of a positive electrode, a negative electrode, an electrolyte and a separator, and realizes the storage and release of electric energy through chemical reactions. In this embodiment, the positive electrode material of the battery cell is lithium iron phosphate.

[0025] The heat insulation pad is used to block the heat transfer between two battery cells. The material of the heat insulation pad is generally aerogel, ceramicized foam, heat insulation silica gel foam, ceramicized silicone rubber, or PO foam, etc.

[0026] The battery pack design method of this embodiment includes the following steps:

[0027] S1. Determine the thickness d of the battery cell in the first direction, the width l of the battery cell in the second direction, and the capacity c of the battery cell; the first direction is perpendicular to the second direction.

[0028] S2. Calculate c / d and l / d.

[0029] S3. Compare the magnitudes of c / d and 2.8 Ah / mm, and the magnitudes of l / d and 6.4. When c / d ≤ 2.8 Ah / mm and l / d ≤ 6.4, then proceed to S4; when c / d > 2.8 Ah / mm or l / d > 6.4, then proceed to S5.

[0030] S4. Do not set a heat insulation pad between any two battery cells.

[0031] S5. Set a heat insulation pad between at least two battery cells.

[0032] For the battery pack design method of the present invention, the positive electrode material of the battery cell is lithium iron phosphate. If c / d ≤ 2.8 Ah / mm and l / d ≤ 6.4, it indicates that the risk of thermal runaway of the battery cell is relatively low. Even if thermal runaway occurs, it is not easy to spread to the adjacent battery cells. Therefore, no heat insulation pad is set between any two battery cells to improve the space utilization rate of the battery pack and reduce costs; if c / d > 2.8 Ah / mm or l / d > 6.4, it indicates that the risk of thermal runaway of the battery cell increases, and a heat insulation pad is set between at least two battery cells to improve the heat insulation performance between the battery cells, thereby ensuring the safety of the battery pack.

[0033] In one embodiment, setting a heat insulation pad between at least two battery cells includes the following steps:

[0034] Set a heat insulation pad between any two adjacent battery cells.

[0035] By setting a heat insulation pad between any two adjacent battery cells, when any one battery cell has a thermal runaway, it will not quickly spread to the adjacent battery cells, thereby making the battery pack safer.

[0036] For the sake of convenience in description, a plurality of battery cells are divided into a plurality of battery cell groups, and each battery cell group includes a plurality of battery cells.

[0037] As an alternative solution, setting a heat insulation pad between at least two battery cells includes the following steps:

[0038] Set a heat insulation pad between two adjacent battery cell groups.

[0039] By arranging heat insulation pads between adjacent battery cell groups, when a battery cell in one battery cell group experiences thermal runaway, it will not quickly spread to the adjacent battery cell group, thereby ensuring the safety of the battery pack to a certain extent, improving the space utilization rate of the battery pack, and reducing costs.

[0040] As another alternative, the multiple battery cell groups include a first battery cell group; arranging heat insulation pads between at least two battery cells includes the following steps:

[0041] Arrange heat insulation pads between adjacent battery cell groups, and do not arrange heat insulation pads between adjacent battery cells in the first battery cell group.

[0042] By arranging heat insulation pads between adjacent battery cell groups and not arranging heat insulation pads between adjacent battery cells in the first battery cell group, when a battery cell in one battery cell group experiences thermal runaway, the generated heat mainly transfers within the battery cell group and will not quickly spread to the adjacent battery cell group. On the premise of improving the safety of the battery pack, the heat insulation pads will not overly increase the space occupied by the battery pack, achieving the effects of improving the space utilization rate of the battery pack and reducing costs.

[0043] Furthermore, the multiple battery cell groups further include a second battery cell group; arranging heat insulation pads between at least two battery cells includes the following steps:

[0044] Arrange heat insulation pads between adjacent battery cell groups, and arrange heat insulation pads between adjacent battery cells in the second battery cell group.

[0045] By blocking the heat transfer between adjacent battery cell groups and between adjacent battery cells in the second battery cell group with heat insulation pads, the risk of adjacent battery cells experiencing thermal runaway when a battery cell in the second battery cell group experiences thermal runaway is reduced, and the risk of adjacent battery cell groups experiencing thermal runaway when a battery cell in one battery cell group experiences thermal runaway is reduced.

[0046] That is to say, arrange heat insulation pads between adjacent battery cell groups, do not arrange heat insulation pads between adjacent battery cells in the first battery cell group, and arrange heat insulation pads between adjacent battery cells in the second battery cell group. Thus, on the premise of improving the safety of the battery pack, the heat insulation pads will not overly increase the space occupied by the battery pack, achieving the effects of improving the space utilization rate of the battery pack and reducing costs.

[0047] As yet another alternative, the multiple battery cells are divided into multiple battery cell groups, and each battery cell group includes multiple battery cells; arranging heat insulation pads between at least two battery cells includes the following steps:

[0048] A first heat insulation pad is arranged between two adjacent battery monomer groups, and a second heat insulation pad is arranged between two adjacent battery monomers in the same battery monomer group.

[0049] That is to say, heat insulation pads are arranged both between two adjacent battery monomer groups and between two adjacent battery monomers in the same battery monomer group, and the heat insulation pads between two adjacent battery monomer groups are set differently from those between two adjacent battery monomers in the same battery monomer group. Further, when a heat runaway occurs in one battery monomer, it will not affect the adjacent battery monomers in the same group through the second heat insulation pad, and when a heat runaway occurs in one battery monomer group, it will not affect the adjacent battery monomer group through the first heat insulation pad, thereby making the battery pack safer.

[0050] Exemplarily, parameters such as the thickness and thermal conductivity of the first heat insulation pad are selected according to the size and capacity of the battery monomer group, and parameters such as the thickness and thermal conductivity of the second heat insulation pad are selected according to the size and capacity of the battery monomer, so as to ensure that the heat insulation and buffering effects of the first heat insulation pad and the second heat insulation pad can meet the requirements.

[0051] In a specific embodiment of the present invention, the thickness of the first heat insulation pad is not less than that of the second heat insulation pad. It should be noted that by arranging the second heat insulation pad between two adjacent battery monomers in the same battery monomer group, the purpose of improving the heat insulation performance between two adjacent battery monomers can already be achieved. On this basis, making the thickness of the first heat insulation pad not less than that of the second heat insulation pad can further improve the heat insulation performance between two adjacent battery monomer groups, thereby reducing the risk of heat runaway of an adjacent battery monomer group when a heat runaway occurs in one battery monomer group, so as to make the battery pack safer.

[0052] In a specific embodiment of the present invention, the thermal conductivity of the first heat insulation pad is not greater than that of the second heat insulation pad. It should be noted that by arranging the second heat insulation pad between two adjacent battery monomers in the same battery monomer group, the purpose of improving the heat insulation performance between two adjacent battery monomers can already be achieved. On this basis, making the thermal conductivity of the first heat insulation pad not greater than that of the second heat insulation pad can further improve the heat insulation performance between two adjacent battery monomer groups, thereby reducing the risk of heat runaway of an adjacent battery monomer group when a heat runaway occurs in one battery monomer group, so as to make the battery pack safer.

[0053] It should be noted that the number of heat insulation pads arranged between two adjacent battery monomers or two adjacent battery monomer groups in this embodiment is not limited. For example, one heat insulation pad can be arranged between two adjacent battery monomers or two adjacent battery monomer groups, or two, three, or even more heat insulation pads can be arranged.

[0054] In one embodiment, an insulating layer is provided on the surface of the housing of the battery cell, and the thickness of the insulating layer ranges from 80 μm to 170 μm. Further, when no heat insulation pad is provided between any two battery cells, the distance between two adjacent battery cells is not less than 0.2 mm. By providing the insulating layer on the surface of the housing to make the housing insulated, the insulating layer can be a PET film or an insulating coating. By making the thickness of the insulating layer range from 80 μm to 170 μm, the purpose of improving the insulation of the housing can be achieved. Furthermore, when no heat insulation pad is provided between any two battery cells, by limiting the distance between two adjacent battery cells to be not less than 0.2 mm, the safety of the battery pack can be ensured; if the distance between two adjacent battery cells is too small, the risk of thermal runaway of an adjacent battery cell will increase when one battery cell experiences thermal runaway.

[0055] In one embodiment, when no heat insulation pad is provided between any two battery cells, the width l of the battery cell in the second direction ranges from 100 mm to 220 mm. If the width l of the battery cell in the second direction is too small, the capacity of the battery cell will be too small to meet the user's needs; if the width l of the battery cell in the second direction is too large, the capacity of the battery cell will be too large, and the heat generated when one battery cell experiences thermal runaway will also be large, increasing the risk of thermal runaway of adjacent battery cells. By limiting the width l of the battery cell in the second direction to range from 100 mm to 220 mm, the capacity and safety of the battery pack can be balanced when no heat insulation pad is provided.

[0056] In one embodiment, when no heat insulation pad is provided between any two battery cells, the capacity c of the battery cell ranges from 50 Ah to 120 Ah. If the capacity c of the battery cell is too small, it will be difficult to meet the user's needs; if the capacity c of the battery cell is too large, the heat generated when one battery cell experiences thermal runaway will also be large, increasing the risk of thermal runaway of adjacent battery cells. By limiting the capacity c of the battery cell to range from 50 Ah to 120 Ah, the safety of the battery pack and the user's needs can be balanced when no heat insulation pad is provided.

[0057] Note that the above is only the preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described here. Various obvious changes, re-adjustments, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A battery pack design method, characterized in that, The battery pack includes a plurality of battery cells stacked in a first direction, and the positive electrode material of the battery cells is lithium iron phosphate; the first direction is perpendicular to the large surface of the battery cells; The battery pack design method includes the following steps: Determine the thickness d of the battery cell in the first direction, the width l of the battery cell in a second direction, and the capacity c of the battery cell; the first direction is perpendicular to the second direction; Calculate c / d and l / d; Compare the magnitude of c / d with 2.8 Ah / mm and the magnitude of l / d with 6.4; When c / d ≤ 2.8 Ah / mm and l / d ≤ 6.4, no heat insulation pad is provided between any two of the battery cells; When c / d > 2.8 Ah / mm or l / d > 6.4, a heat insulation pad is provided between at least two of the battery cells.

2. The battery pack design method according to claim 1, wherein Providing a heat insulation pad between at least two of the battery cells includes the following steps: A heat insulation pad is provided between any two adjacent battery cells.

3. The battery pack design method according to claim 1, wherein, The plurality of battery cells are divided into a plurality of battery cell groups; Providing a heat insulation pad between at least two of the battery cells includes the following steps: A heat insulation pad is provided between two adjacent battery cell groups.

4. The battery pack design method according to claim 1, wherein The plurality of battery cells are divided into a plurality of battery cell groups, and the plurality of battery cell groups include a first battery cell group, and the first battery cell group includes a plurality of the battery cells; Providing a heat insulation pad between at least two of the battery cells includes the following steps: A heat insulation pad is provided between two adjacent battery cell groups, and no heat insulation pad is provided between two adjacent battery cells in the first battery cell group.

5. The battery pack design method according to claim 1, characterized in that, The plurality of battery cells are divided into a plurality of battery cell groups, and each battery cell group includes a plurality of the battery cells; Providing a heat insulation pad between at least two of the battery cells includes the following steps: A first heat insulation pad is provided between two adjacent battery cell groups, and a second heat insulation pad is provided between two adjacent battery cells in the same battery cell group.

6. The battery pack design method according to claim 7, wherein The thickness of the first heat insulation pad is not less than the thickness of the second heat insulation pad.

7. The battery pack design method according to claim 7, characterized in that The thermal conductivity of the first heat insulation pad is not greater than the thermal conductivity of the second heat insulation pad.

8. The battery pack design method according to any one of claims 1-7, characterized in that The battery cell includes a housing and an insulating layer provided on the surface of the housing, and the thickness of the insulating layer ranges from 80 μm to 170 μm; When no heat insulation pad is provided between any two battery cells, the distance between two adjacent battery cells is not less than 0.2 mm.

9. The battery pack design method according to any one of claims 1-7, characterized in that, When no heat insulation pad is provided between any two battery cells, the width l of the battery cell in the second direction ranges from 100 mm to 220 mm.

10. The battery pack design method according to any one of claims 1-7, characterized in that, When no heat insulation pad is provided between any two battery cells, the capacity c of the battery cell ranges from 50 Ah to 120 Ah.

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