Battery cell and electric equipment
By using flame-retardant sheets with closed vesicles to store flame retardants in the battery cell, the problems of the flame retardant's impact on electrical performance and release lag are solved, achieving early suppression of thermal runaway and improving the safety and electrical performance of the battery cell.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH
- Filing Date
- 2025-07-16
- Publication Date
- 2026-05-08
AI Technical Summary
In existing technologies, flame retardants affect electrical performance and have a delayed release time, making it difficult to suppress the development of thermal runaway in the early stages of cell thermal runaway.
The flame retardant is stored in closed vesicles and released directly into the electrolyte through the melting of the flame retardant sheet, avoiding the delay of microcapsule rupture. The foaming process is used to control the formation of vesicles to ensure early release.
It reduces the impact of flame retardants on electrical performance and can rapidly suppress the development of thermal runaway in the early stages of cell thermal runaway, thereby improving the safety and reliability of the cell.
Smart Images
Figure CN224217497U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery technology, specifically to battery cells and electrical equipment. Background Technology
[0002] During use, battery cells may experience thermal runaway due to factors such as compression or impact, leading to dangerous situations such as overheating, fire, or even explosion, seriously threatening the lives and property of users. Therefore, flame retardants are needed to suppress the thermal runaway process of battery cells.
[0003] In some related technologies, flame retardants are filled into microcapsules and mixed with electrolyte. During normal use, the flame retardant does not come into contact with the electrolyte. When the battery cell experiences thermal runaway, the electrolyte is heated and the heat is conducted to the microcapsules, causing the microcapsules to rupture and release the flame retardant inside, thus inhibiting the further development of thermal runaway.
[0004] However, the addition of other substances to the electrolyte can affect its electrical properties. At the same time, the temperature required for microcapsule rupture is relatively high, which leads to a delay in the release time of the flame retardant and makes it difficult to suppress the development of thermal runaway in the early stages. Utility Model Content
[0005] In view of this, the present invention provides a battery cell and an electrical device to solve the problems of flame retardants affecting electrical performance and the delayed release time of flame retardants.
[0006] In a first aspect, the present invention provides a battery cell, comprising a battery cell housing, a battery cell assembly, and a flame retardant sheet. The battery cell housing has a receiving cavity, the battery cell assembly is disposed within the receiving cavity, and the flame retardant sheet is disposed within the receiving cavity and comprises a body and a flame retardant. The body has a plurality of hollow vesicles inside, and the flame retardant is filled in at least a portion of the vesicles. The body is capable of releasing the flame retardant in the vesicles when it melts.
[0007] Beneficial effects: On the one hand, the flame retardant is stored in the flame retardant sheet, thereby avoiding the introduction of other substances into the electrolyte of the battery cell and reducing the impact of the flame retardant on the electrical performance of the battery cell; on the other hand, the flame retardant sheet has closed vesicles, and the flame retardant is directly filled in the vesicles. When the battery cell experiences thermal runaway, the flame retardant sheet melts when heated, causing the structure of the vesicles to be destroyed, directly releasing the internal flame retardant into the electrolyte. This eliminates the need to wait for the microcapsules to rupture, allowing the flame retardant to intervene in the thermal runaway process of the battery cell earlier, which is beneficial for suppressing the development of thermal runaway in its early stages.
[0008] In one alternative embodiment, the flame retardant sheet further includes a flame retardant gas filled in at least a portion of the vesicles.
[0009] In one alternative embodiment, the flame retardant sheet further includes a sandwich layer disposed inside the body, the sandwich layer being made of an inorganic non-metallic material.
[0010] In one alternative embodiment, the interlayer has a thickness direction, and the interlayer has a connecting hole that extends through the thickness direction, with a portion of the main body filling the connecting hole.
[0011] In one alternative embodiment, the number of connection holes is multiple, and the multiple connection holes are arranged at intervals along the edge of the interlayer.
[0012] In one optional embodiment, the inorganic non-metallic material includes any one of glass fiber, mica sheet, and ceramic aerogel.
[0013] In one alternative embodiment, the interlayer has a length direction and a width direction, wherein in the length direction, the length of the interlayer is 50% to 90% of the length of the main body, and in the width direction, the width of the interlayer is 50% to 90% of the width of the main body.
[0014] In one alternative embodiment, the flame retardant sheet is in contact with at least two surfaces of the battery cell assembly.
[0015] In one alternative embodiment, the flame retardant sheet is disposed at the center of the cell assembly.
[0016] Secondly, this utility model also provides an electrical device, including a battery cell provided by this utility model, wherein the battery cell serves as the power supply for the electrical device.
[0017] The electrical equipment includes the battery cell provided by this utility model, and therefore has the beneficial effects brought by the battery cell, which will not be elaborated here. Attached Figure Description
[0018] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0019] Figure 1 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present utility model;
[0020] Figure 2 for Figure 1 A side sectional view of the flame-retardant sheet in the embodiment;
[0021] Figure 3 for Figure 1 A front sectional view of the flame-retardant sheet in the embodiment;
[0022] Figure 4 This is a schematic diagram of another battery cell according to an embodiment of the present invention, which shows another assembly method of the flame retardant sheet in the battery cell;
[0023] Figure 5 This is a schematic diagram of another type of battery cell according to an embodiment of the present invention, which shows another assembly method of the flame retardant sheet in the battery cell.
[0024] Explanation of reference numerals in the attached figures:
[0025] 1. Flame retardant sheet; 101. Main body; 102. Flame retardant; 103. Interlayer; 1031. Connecting hole; 104. Vesicle; 2. Cell housing; 3. Cell assembly; 4. Insulating sheet; X, length direction; Y, width direction; Z, thickness direction. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0027] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a," "an," and "comprising" as used herein may also mean including the plural forms. The terms "comprising," "including," and "having" are inclusive and therefore indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.
[0028] Although terms such as "first," "second," etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Furthermore, in the description of this utility model, unless otherwise expressly specified and limited, the terms "set up" and "connected" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0029] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "end," "length," "inner," "outer," etc. Such spatial relative terms are intended to include different orientations of the mechanism in use or operation, in addition to those depicted in the figure. For example, if the mechanism in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The mechanism may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.
[0030] Battery cells pose a risk of thermal runaway during use. Related technologies encapsulate flame retardants in microcapsules, which are then mixed with the electrolyte. During normal use, the flame retardant does not contact the electrolyte. In the event of thermal runaway, the microcapsules rupture due to heat, releasing the flame retardant 102 into the electrolyte. This flame retardant exerts its cooling and flame-retardant effect through endothermic reaction and the covering of thermal decomposition products. However, impurities in the electrolyte can negatively impact electrical performance, and the relatively high temperature required for microcapsule rupture delays the release of the flame retardant, making it difficult to suppress the development of thermal runaway in its early stages.
[0031] The following is combined Figures 1 to 5 The following describes embodiments of the present invention.
[0032] Reference Figure 1 , Figure 2 , Figure 3According to an embodiment of this utility model, in one aspect, a battery cell is provided, including a battery cell housing 2, a battery cell assembly 3, and a flame-retardant sheet 1. The battery cell housing 2 has a receiving cavity, the battery cell assembly 3 is disposed within the receiving cavity, and the flame-retardant sheet 1, disposed within the receiving cavity, includes a main body 101 and a flame retardant 102. The main body 101 has a plurality of hollow vesicles 104 inside, and the flame retardant 102 fills at least a portion of the vesicles 104. The main body 101 is capable of releasing the flame retardant 102 from the vesicles 104 when it melts. In this application, the battery cell assembly 3 is a wound core or a stacked core obtained by sequentially stacking a positive electrode sheet, a separator, and a negative electrode sheet, or by stacking and then winding them. The battery cell 1 is obtained by placing the battery cell assembly 3 in the receiving cavity of the battery cell housing 2, injecting electrolyte, and then encapsulating it.
[0033] On the one hand, flame retardant 102 is stored in flame retardant sheet 1, thereby preventing other substances from being mixed into the electrolyte of the battery cell and reducing the impact of flame retardant 102 on the electrical performance of the battery cell.
[0034] On the other hand, the flame retardant sheet 1 has a closed vesicle 104, and the flame retardant 102 is directly filled in the vesicle 104 instead of being placed in the main body 101 through microcapsules. When the battery cell experiences thermal runaway, the flame retardant sheet 1 melts due to heat, causing the structure of the vesicle 104 to be destroyed, and the flame retardant 102 inside is directly released into the electrolyte. This eliminates the need to wait for the microcapsules to rupture, allowing the flame retardant 102 to intervene in the thermal runaway process of the battery cell earlier, which is beneficial to suppress the development of thermal runaway in the early stage.
[0035] Understandably, the material of the main body 101 can generally be the foaming material commonly used in flame-retardant sheets 1 in related technologies, meaning that the main body 101 is manufactured through a foaming process. This foaming process involves a foaming agent generating foaming gas, which causes the molten foaming material to expand and take shape. To ensure that the flame-retardant sheet 1 forms closed vesicles 104 as much as possible during the foaming process (rather than the externally connected pores typically formed in related technologies), and to prevent the flame retardant 102 from filling the pores and being uncontrollably released into the electrolyte, process control of the foaming process is necessary.
[0036] On the one hand, the escaping of foaming gas generated during the foaming process can be prevented by increasing the air pressure in the preparation environment. On the other hand, the volume of foaming gas generated can be reduced by appropriately reducing the amount of foaming agent and rapidly cooling after foaming to seal the foaming gas inside.
[0037] In addition to using foamed materials, the main body 101 may also be made of other materials, as long as they can form closed vesicles 104 inside and are suitable for encapsulating flame retardant 102 inside the vesicles 104. This utility model does not impose any restrictions on this.
[0038] In order to release the flame retardant in a timely manner in the event of thermal runaway, the melting point of the main body 101 is optionally 90 to 200°C, preferably 90 to 110°C.
[0039] Optionally, the total volume of the vesicles 104 accounts for 20% to 50% of the volume of the flame retardant sheet 1. The volume ratio of the vesicles 104 in the flame retardant sheet 1 determines the total amount of flame retardant 102 in the flame retardant sheet 1. If the flame retardant 102 is insufficient, the flame retardant capability of the flame retardant sheet 1 will be insufficient. If there are too many vesicles 104, the manufacturing difficulty of the flame retardant sheet 1 will be too high, and its own strength will be insufficient, which will increase the risk that the flame retardant sheet 1 will accidentally release the flame retardant 102 into the electrolyte when the battery cell is impacted but does not experience thermal runaway. Using a volume ratio of 20% to 50% can balance the two requirements.
[0040] Furthermore, the minimum diameter of vesicle 104 can be set to 0.05 mm to 0.08 mm, and the maximum diameter can be set to 0.1 mm to 0.3 mm.
[0041] To ensure the total amount of flame retardant 102, optionally, when manufacturing the flame retardant sheet 1 using a foaming process, the mass ratio of the main body 101 material to the flame retardant can be set to 1:(0.25-2). Optionally, the flame retardant 102 can specifically be at least one of polyphosphazene, ammonium polyphosphate, phosphate, red phosphorus, and organophosphates. The phosphate can include at least one of zirconium phosphate, calcium phosphate, and zinc phosphate, and the organophosphate can include at least one of guanidine phosphonate, phosphate ester, and phosphite ester. The flame retardant 102 can be in granular form, with particle sizes Dv10 of 5 μm to 10 μm, Dv50 of 10 μm to 50 μm, and Dv99 of 50 μm to 90 μm.
[0042] Optionally, to further improve the ability of the flame retardant sheet 1 to suppress thermal runaway, the flame retardant sheet 1 also includes a flame retardant gas, which is filled in at least a portion of the vesicles 104. After the structure of the vesicles 104 is destroyed by heat, the flame retardant gas and the flame retardant 102 are released together into the electrolyte, providing a better flame retardant effect.
[0043] The flame-retardant gas can be an inert gas or other gas that has the ability to suppress the development of thermal runaway. Optionally, when the foaming material is used as the main material 101, the foaming gas can be used as the flame-retardant gas, thereby enhancing the flame-retardant ability while avoiding the foaming process of the flame-retardant sheet 1 being too complicated.
[0044] For example, a carbon dioxide blowing agent can be used as the blowing agent, which generates carbon dioxide gas during the foaming process to form vesicles 104 containing flame retardant 102 and flame retardant gas (here, carbon dioxide).
[0045] Other options can be used for flame-retardant gases. The flame-retardant gas can be the same as the foaming gas or it can be independent of the foaming gas. For specific selection, please refer to the relevant existing technologies, which will not be elaborated here.
[0046] Optionally, the flame-retardant sheet 1 further includes a sandwich layer 103, which is disposed inside the main body 101. The sandwich layer 103 is made of inorganic non-metallic materials. By adding a sandwich layer 103 made of inorganic non-metallic materials to the flame-retardant sheet 1, the strength of the flame-retardant sheet 1 can be enhanced, allowing it to play a supporting role while performing its flame-retardant function, improving the impact resistance of the battery cell, and helping to reduce the risk of thermal runaway of the battery cell during compression and collision. At the same time, since the sandwich layer 103 is disposed inside the main body 101, it is less likely to hinder the process of releasing the flame retardant 102 outward after the main body 101 melts.
[0047] To improve the support effect of the interlayer 103, optionally, the interlayer 103 has a length direction X and a width direction Y. In the length direction X, the length of the interlayer 103 is 50% to 90% of the length of the main body 101, and in the width direction Y, the width of the interlayer 103 is 50% to 90% of the width of the main body 101. In other words, the interlayer 103 is at least half the size of the main body 101 in both the length and width directions Y, thereby ensuring that the interlayer 103 has sufficient size and area to meet the impact resistance requirements.
[0048] In addition, the interlayer 103 also has a thickness direction Z. The thickness of the interlayer 103 can be set to 20% to 40% of the total thickness of the flame retardant sheet 1 (if the thickness of the flame retardant sheet 1 is inconsistent, the thickness of the interlayer 103 is 20%-40% of the maximum thickness of the flame retardant sheet 1). If the thickness of the interlayer 103 is too small, its own structure is relatively fragile and it is difficult to meet the impact resistance requirements. If the thickness of the interlayer 103 is too large, it will encroach on the space of the main body 101 and make the flame retardant sheet 1 too large, which will encroach too much on the space inside the cell. Using a thickness range of 20% to 40% can balance the two requirements.
[0049] For example, the inorganic non-metallic material may include any one of glass fiber, mica sheet, and ceramic aerogel. Among them, glass fiber and mica sheet are relatively hard, while ceramic aerogel has high toughness, which can better enhance the mechanical strength of the flame retardant sheet 1, enabling the flame retardant sheet 1 to better perform its mechanical protection function. In addition, glass fiber, mica sheet, and ceramic aerogel also have good thermal insulation effect, which can enhance the thermal insulation and flame retardant ability of the flame retardant sheet 1 and slow down the heat dissipation and heat spread during thermal runaway of the battery cell.
[0050] Optionally, the interlayer 103 has a connecting hole 1031 extending through in the thickness direction Z, and part of the main body 101 is filled in the connecting hole 1031. The main body 101 filled in the connecting hole 1031 connects the main bodies 101 located on both sides of the interlayer 103 in the thickness direction Z together, forming an anchor point to prevent the main body 101 from separating from the interlayer 103, so that the main body 101 is more tightly bonded to the interlayer 103.
[0051] For example, there are multiple connection holes 1031, which are spaced apart along the edge of the interlayer 103. Each connection hole 1031 forms an anchor point, and the multiple anchor points surround the edge of the interlayer 103, thereby further improving the reliability of the connection.
[0052] Specifically Figure 3 In the illustrated embodiment, the interlayer 103 is square in shape and has four circular connection holes 1031 of the same diameter. The four connection holes 1031 are distributed at the four corners of the interlayer 103, thereby achieving a firm connection between the interlayer 103 and the main body 101.
[0053] Optionally, the minimum distance from the center of the connection hole 1031 to the edge of the interlayer 103 is greater than or equal to a safety distance, which is set to 1.5 times the diameter of the connection hole 1031. It is understood that for some fragile inorganic non-metallic materials, a connection hole 1031 too close to the edge of the interlayer 103 increases the risk of the interlayer 103 breaking during processing. By setting a safety distance for the distance from the connection hole 1031 to the edge, the yield of the interlayer 103 can be improved, which helps to reduce the manufacturing cost of the battery cell.
[0054] Optionally, the flame-retardant sheet 1 and the surface of the battery cell assembly 3 are in contact. In the event of thermal runaway, the temperature of the battery cell assembly 3 rises first. By contacting the flame-retardant sheet 1 with the battery cell assembly 3, the temperature change of the battery cell assembly 3 can be detected more sensitively, allowing it to heat up and melt earlier, thus releasing the flame retardant 102 in a timely manner. Furthermore, the flame-retardant sheet 1 can contact at least two surfaces of the battery cell assembly 3, providing more comprehensive protection for the battery cell assembly 3.
[0055] Flame retardant sheet 1 can contact different surfaces of battery cell assembly 3, for example, see reference. Figure 1 and Figure 4 The flame retardant sheet 1 can be disposed on the outer side of the battery cell assembly 3, and there are multiple flame retardant sheets 1.
[0056] Specifically Figure 1 In the illustrated embodiment, there are two battery cell assemblies 3, which are stacked together, and multiple flame-retardant sheets 1 surround the two battery cell assemblies 3. Figure 4In the illustrated embodiment, there is one battery cell assembly 3, with two flame-retardant sheets 1 respectively disposed on two large surfaces of the battery cell assembly 3. This utilizes the mechanical strength of the flame-retardant sheets 1 to provide effective mechanical protection for the battery cell assembly 3, resisting puncture by external forces or mitigating deformation caused by external forces, thereby reducing the risk of short circuits and thermal runaway caused by external damage. Especially in pouch cells, where the mechanical strength of the cell casing 2 is relatively weak, the flame-retardant sheets 1 can significantly reduce the risk of short circuits and thermal runaway caused by external damage to the battery cell assembly 3.
[0057] When Figure 1 and Figure 4 As shown in the embodiments, when the flame retardant sheet 1 is applied to the outer surface of the battery cell assembly 3, the material of the main body 101 may include one or more of epoxy acrylate resin and PEA (polyesteramide). These materials have low melting points and high mechanical strength, and as the material of the main body 101, they can provide strong mechanical protection.
[0058] For example, refer to Figure 5 The flame-retardant sheet 1 is located at the center of the battery cell assembly 3. Specifically, in Figure 5 In the illustrated embodiment, the battery cell assembly 3 is formed by a winding process using a positive electrode sheet, a separator, and a negative electrode sheet. Therefore, the middle (inner ring) of the battery cell assembly 3 has an insertable space. At this time, the inserted flame-retardant sheet 1 plays a supporting and separating role, opening up the battery cell assembly 3 and optimizing the interface contact of the electrode sheets in the inner ring of the battery cell assembly 3, thereby improving the long-term cycle performance of the battery cell.
[0059] When Figure 5 As shown in the embodiments, when the flame-retardant sheet 1 is applied to the center of the battery cell assembly 3 manufactured using a winding process, the material of the main body 101 may include one or more of EVA (ethylene-vinyl acetate copolymer), POE (polymer of ethylene and butane / octene), PEO (polyethylene glycol), and PCL (polycaprolactone). These materials possess high elasticity, flexibility, and adhesion, and as the material of the main body 101, they can provide good support for the battery cell assembly while also ensuring better contact with the center of the battery cell assembly.
[0060] In addition, the flame retardant sheet 1 can also be fixed in different ways to maintain contact with the battery cell assembly 3. For example, the flame retardant sheet 1 can be glued with high-temperature adhesive or glued by melting the main body 101.
[0061] Specifically Figure 1In the illustrated embodiment, the battery cell further includes an insulating sheet 4, which is located between the battery cell assembly 3 and the battery cell housing 2, serving an insulating function. A flame-retardant sheet 1 can be adhered to the center of the inner surface of the insulating sheet 4 using high-temperature adhesive. The insulating sheet 4 can be a Mylar sheet or other structures used in related technologies to achieve insulation; this invention does not limit its application.
[0062] exist Figure 4 In the illustrated embodiment, the flame retardant sheet 1 can be attached to the surface of the battery cell assembly 3 after hot pressing. The residual heat of the surface (slightly exceeding the melting temperature of the main body 101, for example, about 90°C) is used to melt the surface of the flame retardant sheet 1 and then cool it to adhere it to the surface of the battery cell assembly 3.
[0063] When Figure 1 and Figure 4 As shown in the embodiments, when the flame retardant sheet 1 is applied to the outer surface of the battery cell assembly 3, the flame retardant sheet 1 can be set to have a uniform thickness at all locations. The flame retardant sheet 1 is located in the middle of the surface to which it is attached, and its length and width are smaller than the length and width of the surface to which the flame retardant sheet 1 is attached, respectively, so as to prevent the edge of the flame retardant sheet 1 from extending beyond the edge of the surface to which it is attached.
[0064] For example, the thickness of the flame retardant sheet 1 can be 0.5mm to 5mm, and its length and width are 1mm to 4mm less than the length and width of the surface on which the flame retardant sheet 1 is attached.
[0065] And in Figure 5 In the illustrated embodiment, the flame retardant sheet 1 can be placed inside the center of the battery cell assembly 3 after winding and before hot pressing (for example, the flame retardant sheet 1 is inserted when the battery cell assembly 3 is pulled out). The hot pressing process allows the battery cell assembly 3 to reliably press the flame retardant sheet 1. At the same time, the temperature needs to be controlled during hot pressing to avoid the center temperature of the battery cell assembly 3 being too high, which would cause the flame retardant sheet 1 to melt excessively and release the flame retardant 102 prematurely.
[0066] When Figure 5 As shown in the embodiments, when the flame retardant sheet 1 is applied to the center of the battery cell assembly 3 manufactured by the winding process, the length direction of the flame retardant sheet 1 is parallel to the height direction of the battery cell assembly 3 (that is, the axial direction during winding). In the length direction, the thickness of the flame retardant sheet 1 is uniform, and in the width direction, the thickness of the flame retardant sheet 1 gradually decreases from the middle to both ends, so as to better adapt to the space of the center of the battery cell assembly 3.
[0067] For example, the thickness of the middle region of the flame retardant sheet 1 can be 0.5mm to 5mm, the width of the middle region accounts for 60-95% of the total width of the flame retardant sheet 1, the minimum thickness of both ends of the flame retardant sheet 1 is 0.05mm to 0.2mm, the length and width of the flame retardant sheet 1 are 0.5mm to 1mm less than the length and width of the space at the center of the battery cell assembly 3, and the flame retardant sheet 1 is inserted in the middle position at the center of the battery cell assembly 3.
[0068] The following embodiments and comparative examples will provide a clearer understanding of the battery cell and flame retardant sheet 1 in this invention.
[0069] Example 1:
[0070] The arrangement of the flame retardant sheet 1 in Example 1 can be referred to Figure 5 The illustrated embodiment.
[0071] In the length direction, the thickness of the flame retardant sheet 1 is uniform. In the width direction, the thickness of the middle part of the flame retardant sheet 1 is the largest and uniform, which is 1mm. The width of the middle part accounts for 90% of the total width of the flame retardant sheet 1. The thickness of the middle part decreases uniformly from the edge to both ends, and the minimum thickness at both ends is 0.1mm. The length and width are 0.5mm less than the length and width of the inner center surface of the core, respectively.
[0072] The thickness of the interlayer 103 is 30% of the maximum thickness of the flame-retardant sheet 1. The thickness of the interlayer 103 is consistent in all directions, and its length and width are 80% of the length and width of the flame-retardant sheet 1. The interlayer 103 has four circular connecting holes 1031 of the same diameter on its length and width sides. Each connecting hole 1031 penetrates the interlayer 103. The diameter of each connecting hole 1031 is the same in the thickness direction, and its diameter is 8% of the width of the interlayer 103. The minimum distance between the center of each connecting hole 1031 and the length and width edges of the interlayer 103 is 1.5 times the diameter of the connecting hole 1031. The connecting holes 1031 are filled by the main body 101, firmly bonding the main body 101 and the interlayer 103 together.
[0073] Multiple spherical vesicles 104 are uniformly dispersed within the main body 101. Each vesicle 104 is filled with granular flame retardant 102. When the flame-retardant sheet 1 is subjected to high-temperature melting, the vesicles 104 rupture, releasing the flame retardant 102. This flame retardant absorbs heat and exerts its cooling and flame-retardant effect through the coating of thermal decomposition products. The minimum diameter of the vesicles 104 in the flame-retardant sheet 1 is 0.06 mm, and the maximum diameter is 0.2 mm. The total volume of all vesicles 104 accounts for 40% of the volume of the flame-retardant sheet 1. The particle sizes of the flame retardant 102 are Dv10 (9 μm), Dv50 (45 μm), and Dv99 (80 μm).
[0074] Example 2:
[0075] The arrangement of the flame retardant sheet 1 in Example 2 can be referred to Figure 4 The illustrated embodiment.
[0076] The difference between Example 2 and Example 1 is that the flame retardant sheet 1 in Example 2 has a uniform thickness of 2mm, and its length and width are 1mm less than the length and width of the large surface of the battery cell assembly 3.
[0077] The flame retardant sheet 1 is attached to the outer surface of the battery cell assembly 3. After the battery cell assembly 3 is hot-pressed, the residual heat (about 90°C) on the surface of the battery cell assembly 3 is used to melt the surface of the flame retardant sheet 1 and then cool it, so that it is stuck to the center of the two large surfaces of the battery cell assembly 3.
[0078] Example 3:
[0079] The arrangement of the flame retardant sheet 1 in Example 3 can be referred to Figure 1 The illustrated embodiment.
[0080] The difference between Example 3 and Example 1 is that the flame retardant sheet in Example 3 has a uniform thickness of 1.5 mm, and its length and width are 2 mm less than those of the insulation sheet 4 used.
[0081] The flame retardant sheet 1 is attached to the inner surface of the insulating sheet 4, and the flame retardant sheet 1 is glued to the center of the inner surface using 800℃ high-temperature adhesive.
[0082] Example 4:
[0083] The arrangement of the flame retardant sheet 1 in Example 4 can be referred to Figure 1 The illustrated embodiment.
[0084] The difference between Example 4 and Example 1 is that the total volume of all vesicles 104 in the flame retardant sheet 1 of Example 4 accounts for 20% of the volume of the flame retardant sheet 1.
[0085] Example 5:
[0086] The arrangement of the flame retardant sheet 1 in Example 5 can be referred to Figure 1 The illustrated embodiment.
[0087] The difference between Example 5 and Example 1 is that the flame retardant sheet 1 does not contain the interlayer 103.
[0088] Comparative Example 1:
[0089] The difference between Comparative Example 1 and Example 1 is that the battery cell does not contain flame retardant sheet 1 or flame retardant 102.
[0090] Comparative Example 2:
[0091] The arrangement of flame retardant sheet 1 in Comparative Example 2 can be referred to Figure 1The illustrated embodiment.
[0092] The difference between Comparative Example 2 and Example 1 is that the flame retardant sheet 1 does not contain vesicles 104, and the flame retardant 102 is uniformly dispersed in the main body 101.
[0093] The battery cells from Examples 1 to 5 and Comparative Examples 1 to 2 were subjected to performance tests. The specific test items are as follows:
[0094] 1. Flame retardant properties
[0095] The fully charged battery cells were heated from 25°C to 180°C at a rate of 5°C / min and held for 30 minutes. The state of the battery cells was recorded. The battery cells that caught fire had poor flame retardant performance. The battery cells that did not catch fire but had the explosion-proof valve open had average flame retardant performance. The battery cells that did not catch fire and had the explosion-proof valve closed had good flame retardant performance.
[0096] 2. Needle prick test
[0097] Insert a 3mm diameter steel needle into the center of the large surface of a fully charged battery cell at a 45° angle and a speed of 25mm / s. Observe for 1 hour. If the battery cell does not catch fire or explode, it passes the needle penetration test. If the battery cell catches fire or explodes, it fails the needle penetration test.
[0098] 3. Thermal diffusion test
[0099] Three battery cells are connected in series to form a simple module, with 1mm thick U-shaped frames separating the cells. In a sealed box at room temperature, a 1000W heating element is used to trigger thermal runaway of the first battery cell on the left. The thermal runaway of adjacent cells is recorded. If adjacent cells do not catch fire or explode, the thermal runaway test is passed. If adjacent cells catch fire or explode, the thermal runaway test is not passed.
[0100] 4. Capacity retention after 500 cycles
[0101] At 25°C, the battery cell is cyclically charged and discharged at a 1C rate (between the lower and upper voltage limits). The discharge capacity of the 1st and 500th cycles is recorded, and the ratio of the discharge capacity of the 500th cycle to the discharge capacity of the 1st cycle is calculated, which is the capacity retention rate after 500 cycles.
[0102] The test results are shown in the table below:
[0103]
[0104] As can be seen from the comparative examples and comparative embodiments, the present invention can effectively improve the flame retardant performance of the battery cell.
[0105] Comparing Examples 1, 4, 5 and Examples 2, 3, it can be seen that by inserting the flame-retardant sheet 1 into the middle of the cell assembly 3, it plays a supporting and separating role, which can open up the cell assembly 3, optimize the interface contact of the electrode sheets in the inner ring of the cell assembly 3, and thus improve the long-term cycle performance of the cell.
[0106] Comparing Examples 1, 2, 3, 4 and Example 5, it can be seen that by adding the interlayer 103, the impact resistance and safety of the battery cell can be improved.
[0107] As can be seen from the comparative examples and Comparative Example 2, by storing the flame retardant 102 in the vesicle 104, the flame retardant 102 can be released more rapidly when molten, thereby exerting a more efficient flame retardant effect.
[0108] Secondly, this utility model also provides an electrical device, including a battery cell provided by this utility model, which serves as the power supply for the electrical device.
[0109] The electrical equipment includes the battery cell provided by this utility model, and therefore has the beneficial effects brought by the battery cell, which will not be elaborated here.
[0110] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.
Claims
1. A battery cell, characterized in that, include: The battery cell housing (2) has a receiving cavity; The battery cell assembly (3) is disposed within the accommodating cavity; A flame retardant sheet (1) is disposed within the accommodating cavity and includes a body (101) and a flame retardant (102). The body (101) has a plurality of closed vesicles (104) inside, and the flame retardant (102) is filled in at least a portion of the vesicles (104). The body (101) is capable of releasing the flame retardant (102) in the vesicles (104) when it melts.
2. The battery cell according to claim 1, characterized in that, The flame retardant sheet (1) also includes a flame retardant gas, which is filled in at least a portion of the vesicles (104).
3. The battery cell according to claim 1, characterized in that, The flame retardant sheet (1) also includes a sandwich layer (103), which is disposed inside the main body (101), and the material of the sandwich layer (103) includes inorganic non-metallic materials.
4. The battery cell according to claim 3, characterized in that, The interlayer (103) has a thickness direction (Z), and the interlayer (103) has a connecting hole (1031) that passes through the thickness direction (Z). A portion of the main body (101) is filled in the connecting hole (1031).
5. The battery cell according to claim 4, characterized in that, The number of the connecting holes (1031) is multiple, and the multiple connecting holes (1031) are arranged at intervals along the edge of the interlayer (103).
6. The battery cell according to claim 3, characterized in that, The inorganic non-metallic material includes any one of glass fiber, mica sheet, and ceramic aerogel.
7. The battery cell according to claim 3, characterized in that, The interlayer (103) has a length direction (X) and a width direction (Y). In the length direction (X), the length of the interlayer (103) is 50% to 90% of the length of the main body (101), and in the width direction (Y), the width of the interlayer (103) is 50% to 90% of the width of the main body (101).
8. The battery cell according to claim 1, characterized in that, The flame retardant sheet (1) is in contact with at least two surfaces of the battery cell assembly (3).
9. The battery cell according to claim 1, characterized in that, The flame retardant sheet (1) is disposed at the center of the battery cell assembly (3).
10. An electrical appliance, characterized in that, The battery cell includes any one of claims 1 to 9, wherein the battery cell serves as the power supply for the electrical device.