Safe battery cell and safe battery

Abstract

The utility model provides a safe battery cell and a safe battery, comprising a first pole piece, a diaphragm and a second pole piece which are sequentially laminated and wound into a roll core; the first pole piece comprises a current collector, a first coating and an active substance, the current collector comprises a first region and a second region, the first region and the second region are arranged along the winding direction of the current collector, the first region is arranged at the winding ending end of the current collector, and the first region is exposed outside the winding core; the first coating is arranged on one side, back to the second pole piece, of the first region, the active substance is arranged in the second region, and the first coating has insulativity; a groove is formed in the first coating in the thickness direction of the first pole piece, a bonding layer is arranged in the groove, the bonding layer protrudes out of the first coating in the thickness direction of the first pole piece, and the bonding layer is used for fixing the safety battery cell on the shell. According to the safe battery cell disclosed by the utility model, the energy density of the battery cell can be improved on the premise of ensuring the safety performance of the battery cell.

Description

Technical Field

[0001] This utility model relates to the field of new energy technology, and in particular to a safe battery cell and a safe battery. Background Technology

[0002] With continuous technological advancements and innovation, the demand for various smart devices, especially smartphones and computers, is growing daily. The widespread adoption of these devices has led to higher requirements for the performance and safety of smart products. Among numerous performance indicators, energy density and safety have become the focus of attention for both consumers and manufacturers. To meet these demands, battery cell manufacturers have turned their attention to the structural design of pouch-pack safety batteries. Pouch-pack safety batteries, due to their advantages of being lightweight, flexible, and safe, have gradually become a popular choice in the market. However, the use of cathode foil has become a crucial step in the research and development and production of these safety batteries. To improve the performance and stability of the battery cell, cathode foil typically employs a base coating technology. This technology forms a protective film on the foil surface, thereby enhancing the chemical stability and electrochemical performance of the battery cell. However, in the production of bare batteries, hot melt adhesive is also needed to be applied to the surface of the cathode foil. The main function of the hot melt adhesive is to fix the various components inside the battery cell, ensuring its stability during use. However, the hot melt adhesive is applied on top of the base coating at the end of the cathode sheet, which leads to a problem: the thickness of the base coating and the hot melt adhesive overlaps, thus reducing the energy density of the battery cell to some extent. Energy density refers to the amount of electrical energy that a unit volume or unit mass of battery cell can store. In modern smart devices, high energy density means longer battery life and higher performance. Therefore, battery cell manufacturers must optimize the thickness and materials of each component as much as possible during the design and manufacturing process to minimize energy density loss. Thus, there is a need for a battery cell that can improve energy density while ensuring the cell's safety performance. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a safe battery cell that can improve the energy density of the battery cell while ensuring its safety performance.

[0004] This utility model also proposes a safe battery.

[0005] A safety battery cell according to a first aspect of the present invention includes: a first electrode, a separator, and a second electrode, wherein the first electrode, the separator, and the second electrode are sequentially stacked and wound to form a core; the first electrode includes a current collector, a first coating, and an active material, wherein the current collector includes a first region and a second region, the first region and the second region being disposed along the winding direction of the current collector, the first region being disposed at the end of the winding of the current collector and exposed on the outside of the core, the first coating being disposed on the side of the first region opposite to the second electrode, the active material being disposed in the second region, and the first coating having insulating properties; a groove is formed on the first coating along the thickness direction of the first electrode, an adhesive layer is disposed in the groove, the adhesive layer protruding from the first coating in the thickness direction of the first electrode, and the adhesive layer being used to fix the safety battery cell to a housing.

[0006] The safety battery cell according to the first aspect of the present invention has at least the following beneficial effects: by opening a groove on the first coating and setting the adhesive layer in the groove, the thickness of the first electrode at the location where the adhesive layer is set is reduced, thereby increasing the energy density of the battery cell. At the same time, the adhesive layer set in the groove can also protect the safety of the battery cell to a certain extent, thereby improving the energy density of the battery cell while ensuring its safety. In addition, the battery cell can be fixed on the housing to prevent the battery cell from shaking in the housing.

[0007] According to some embodiments of the present invention, the first electrode further includes a second coating, the second coating being conductive, the second coating being disposed in a second region of the first electrode, and the active material being disposed on the side of the second coating facing away from the current collector.

[0008] According to some embodiments of the present invention, the first region is also provided with the second coating on the side facing the second electrode.

[0009] According to some embodiments of the present invention, the first electrode is a cathode plate.

[0010] According to some embodiments of the present invention, the grooves are provided in multiple ways along the winding direction of the first electrode sheet.

[0011] According to some embodiments of the present invention, the depth of the groove does not exceed the thickness of the first coating in the thickness direction of the first electrode sheet, the thickness of the first coating outside the groove is H1, and the thickness of the first coating inside the groove is H2, where 0.3H1≤H2≤0.8H1.

[0012] According to some embodiments of the present invention, the length of the adhesive layer in the width direction of the first electrode is L1, and the length of the groove in the width direction of the first electrode is L2, where L1≤L2≤L1+10mm.

[0013] According to some embodiments of the present invention, the length of the adhesive layer in the winding direction of the first electrode is W1, and the length of the groove in the winding direction of the first electrode is W2, where W1≤W2≤W1+10mm.

[0014] According to some embodiments of the present invention, the material of the second coating is lithium iron phosphate, and the material of the first coating is ceramic.

[0015] The safety battery according to a second aspect of the present invention is characterized in that it includes the safety cell described in any one of the above embodiments.

[0016] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] Figure 1 This is a front structural diagram of a safety battery cell according to the present invention;

[0018] Figure 2 This is a side view of a safety battery cell according to the present invention.

[0019] Figure 3 This is a cross-sectional structural diagram of a safety battery cell according to the present invention.

[0020] Icon labels:

[0021] 1. Active material; 2. Current collector; 3. First coating; 4. Second coating; 5. Groove; 6. First region; 7. Second region; 8. Adhesive layer. Detailed Implementation

[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying 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 with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0023] In the description of this utility model, it should be understood that the orientation descriptions, such as up and down, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] In the description of this utility model, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features or their sequential relationship.

[0025] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0026] In the intricate processes of battery manufacturing, the tail-end fixation of the wound cell plays a crucial role. This process not only ensures the structural stability of the wound cell during subsequent assembly, packaging, and final use, but also directly impacts the battery's performance and safety. The tail end is typically secured using adhesive tapes of varying materials. These fixation methods must possess sufficient durability to withstand temperature variations, vibrations, and shocks that the battery may encounter under different environmental conditions. In practice, engineers select the most suitable tail-end fixation method based on the cell's material properties, battery design specifications, and the anticipated application scenario. For example, for high-energy-density lithium-ion batteries, tail-end fixation must not only prevent cell displacement during charging and discharging but also ensure that there is no risk of short circuits or overheating under extreme conditions. Therefore, the selection and application technology of fixation materials must undergo rigorous testing and verification to ensure their reliability in long-term use. Furthermore, the design of the tail-end fixation must also consider the overall weight and volume of the battery, as well as its impact on internal chemical reactions. Overly cumbersome or heavy fixation methods may increase the battery's volume and weight, thereby reducing its energy density. Therefore, while ensuring effective mounting, engineers also need to pursue lightweight and compact designs to meet the high performance requirements of modern electronic devices. Through carefully designed tail mounting, battery manufacturers can ensure the competitiveness of their products in the market, providing consumers with safe and efficient energy solutions.

[0027] The needle puncture test for battery cells is a crucial safety performance test that simulates extreme conditions batteries might encounter in real-world scenarios. In this test, a thin steel needle is precisely pierced through the battery cell to examine the battery's reaction when punctured by a sharp object. This process aims to observe whether the battery can withstand physical damage without undergoing dangerous chemical reactions such as short circuits, overheating, fire, or explosion. During the needle puncture test, researchers meticulously record every reaction of the battery, including temperature changes, voltage fluctuations, and any possible gas releases. This data is essential for assessing the battery's structural strength and the effectiveness of its internal protection mechanisms. Through these tests, manufacturers can ensure that batteries remain stable under various potentially hazardous conditions, thus providing consumers with safer battery products. Furthermore, the needle puncture test helps battery designers identify and improve potential weaknesses in battery design. By analyzing the experimental results, engineers can adjust the battery's materials, construction, and safety characteristics to improve overall battery safety performance. Therefore, this test is not only a safety assessment tool but also a significant driving force for battery technology advancement and innovation. Applying a safety coating to the current collector can greatly improve the puncture resistance of the battery cell, thereby enhancing its safety.

[0028] Reference Figure 1 , Figure 2 and Figure 3The safety battery cell in the first embodiment of this utility model includes: a first electrode, a separator, and a second electrode. The first electrode, separator, and second electrode are stacked and wound into a core in sequence. The first electrode includes a current collector 2, a first coating 3, and an active material 1. The current collector 2 includes a first region 6 and a second region 7, which are arranged along the winding direction of the current collector 2. The first region 6 is located at the end of the winding of the current collector 2 and is exposed on the outside of the core. The first coating 3 is located on the side of the first region 6 facing the outside of the core, and the active material 1 is located in the second region 7. The first coating 3 has insulating properties. After the first electrode, separator, and second electrode are wound, the first region 6 on the first electrode is exposed on the outside of the core. When the first electrode is a cathode, and a short circuit occurs in the battery cell, the contact resistance between the anode material area and the current collector 2 of the first electrode is the smallest, the heat generation is the largest, the reaction rate is the fastest, and the danger is the greatest. Therefore, it is necessary to prevent direct contact between the anode material area and the current collector 2 on the first electrode during a short circuit. To prevent the first area 6 of the current collector from directly contacting the anode material area in the event of a short circuit in the battery cell, a coating is applied to the current collector 2 of the first electrode to prevent direct contact between the current collector and the anode material area. Specifically, the first coating 3, facing outwards from the core, is made of an insulating material to prevent direct contact between the first area 6 of the current collector 2 and the anode material area. The first coating 3 can be a ceramic layer. A groove 5 is formed on the first coating 3 along the thickness direction of the first electrode, and an adhesive layer 8 is disposed within the groove 5. The adhesive layer 8 protrudes from the first coating 3 along the thickness direction of the first electrode. To improve the overall energy density of the battery cell, the groove 5 is provided on the first coating 3, so that a portion of the adhesive layer 8 is located within the groove 5, and the portion protruding beyond the groove 5 can be adhered to the casing. After the battery cell is manufactured, it needs to be placed in the casing to fix it relatively. Because the adhesive layer 8 is relatively thick, the groove 5 is provided to reduce the thickness of the adhesive layer 8 protruding from the first coating 3, thereby improving the energy density.

[0029] In a battery cell, when a short circuit occurs, the current collector on the cathode plate and the anode material area come into short-circuit contact. This results in lower internal resistance, faster discharge speed, and greater danger, making the protection of the cathode plate even more crucial. Therefore, the first electrode is designated as the cathode plate. Simultaneously, the cathode plate is located on the outermost layer during the cell winding process. At this time, an adhesive layer 8 is applied to the cathode plate to fix the cell to the housing.

[0030] According to some embodiments of this utility model, the first electrode also includes a second coating 4, which is conductive. The second coating 4 is disposed in the second region 7 of the first electrode, and the active material 1 is disposed on the side of the second coating 4 facing away from the current collector 2. In a safety cell, to improve the safety performance of the cell, a coating, namely the second coating 4, is also disposed between the active material 1 and the current collector 2. The second coating 4 differs from the first coating 3, which is insulating, while the second coating 4 needs to be conductive. However, the conductivity of the second coating 4 should be less than that of the current collector 2. Thus, when a short circuit occurs on the first electrode where the current collector 2 directly contacts the anode material area, the internal resistance of the cell increases, reducing the discharge rate during a short circuit and thus reducing the danger. The second coating 4 can be made of lithium iron phosphate material, which not only protects the current collector 2 but also provides a certain amount of lithium ions, thereby further improving the energy density of the cell. Furthermore, the side of the first region 6 facing away from the inner side of the winding core is also provided with the second coating 4. This ensures high safety when the active material 1 is disposed on the side of the first region 6 facing the inner side of the winding core.

[0031] According to some embodiments of this utility model, the depth of the groove 5 does not exceed the thickness of the first coating 3 in the thickness direction of the first electrode. The thickness of the first coating 3 outside the groove 5 is H1, and the thickness of the first coating 3 inside the groove 5 is H2, where 0.3H1≤H2≤0.8H1. The current collector 2 of the first electrode is typically made of aluminum foil. When the groove 5 is too deep, the thickness of the first coating 3 in the groove area will be smaller, resulting in a greater loss of safety performance. Conversely, when the groove 5 is too shallow, the thickness of the first coating 3 in the groove area will be larger, and the space for the adhesive layer 8 in the groove will be smaller, thus reducing the effect of improving the energy density of the battery. Therefore, H2 is limited to between 0.3 and 0.8 times H1.

[0032] According to some embodiments of this utility model, in the width direction of the first electrode, the width of the adhesive layer 8 does not exceed the width of the groove 5; in the length direction of the first electrode, the length of the adhesive layer 8 does not exceed the length of the groove 5. Furthermore, a certain gap is left between the adhesive layer 8 and the interior of the groove 5. When the adhesive layer 8 is placed within the groove 5 and the battery cell is pressed into the housing for fixation, the adhesive layer 8 can undergo a certain elastic deformation, with a portion of the adhesive layer 8 protruding from the first coating layer 3 and filling the gap. This results in a smaller thickness of the adhesive layer 8, a larger bonding surface area, and prevents the adhesive layer 8 from being squeezed and overflowing from the groove. Specifically, the length of the adhesive layer 8 in the width direction of the first electrode is L1, and the length of the groove 5 in the width direction of the first electrode is L2, where L1≤L2≤L1+10mm. The length of the adhesive layer 8 in the winding direction of the first electrode is W1, and the length of the groove 5 in the winding direction of the first electrode is W2, where W1≤W2≤W1+10mm. This avoids the safety performance being reduced due to an excessively large gap between the adhesive layer 8 and the interior of the groove 5.

[0033] When creating grooves 5 on the first coating 3, multiple grooves 5 can be spaced apart along the winding direction of the first electrode sheet. When fixing the end of the first electrode sheet, the bonding force needs to reach a certain strength. To increase the bonding strength, the bonding area, i.e., the contact area between the adhesive layer 8 and the first electrode sheet, needs to be increased. Since the adhesive layer 8 is located within the grooves 5, the projected area of ​​the grooves 5 in the thickness direction of the first electrode sheet needs to be increased. Therefore, grooves 5 with a larger projected area are required. However, setting a large groove 5 can easily cause misalignment of the adhesive layer 8. Therefore, setting multiple grooves 5 spaced apart along the winding direction of the first electrode sheet satisfies the bonding force requirements between the cell and the casing while preventing misalignment of the adhesive layer 8.

[0034] The embodiment of this solution with grooves in the first coating was tested and compared with the prior art embodiment without grooves in the first coating. The test method was as follows: a steel needle with a diameter of about 5 mm was inserted through the adhesive layer of the battery cell at a speed of 30 mm / s, and the needle remained inside the battery (removed after 1 minute). If no safety incident occurred during this period, the test was considered successful. Ten sets of data were collected for comparison. The prior art embodiment without grooves in the first coating was also tested:

[0035] The first group has a core thickness of 4.082 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0036] The second group has a core thickness of 4.074 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0037] The third group has a core thickness of 4.089 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0038] The fourth group has a core thickness of 4.073 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0039] The fifth group has a core thickness of 4.091 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0040] In the sixth group, the thickness of the core in the thickness direction of the first electrode sheet is 4.076 mm, and it passes the test.

[0041] In the seventh group, the thickness of the core in the thickness direction of the first electrode sheet is 4.072 mm, and it passes the test.

[0042] In the eighth group, the thickness of the core in the thickness direction of the first electrode sheet is 4.067 mm, and it passes the test.

[0043] In the ninth group, the thickness of the core in the thickness direction of the first electrode sheet is 4.069 mm, and it passes the test.

[0044] In the tenth group, the thickness of the core in the thickness direction of the first electrode sheet is 4.069 mm, and it passes the test.

[0045] The average thickness of the ten groups was 4.076 mm, and all passed the test.

[0046] The data for creating grooves on the first coating in this scheme are as follows:

[0047] The first group has a core thickness of 4.071 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0048] The second group has a core thickness of 4.062 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0049] The third group has a core thickness of 4.075 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0050] The fourth group has a core thickness of 4.056 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0051] The fifth group has a core thickness of 4.071 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0052] In the sixth group, the thickness of the core in the thickness direction of the first electrode sheet is 4.068 mm, and it passes the test.

[0053] The seventh group has a core thickness of 4.060 mm in the thickness direction of the first electrode sheet, and it passed the test.

[0054] In the eighth group, the thickness of the core in the thickness direction of the first electrode sheet is 4.058 mm, and it passes the test.

[0055] In the ninth group, the thickness of the core in the thickness direction of the first electrode sheet is 4.065 mm, and it passes the test.

[0056] In the tenth group, the thickness of the core in the thickness direction of the first electrode sheet is 4.057 mm, and it passes the test.

[0057] The average thickness of the ten groups was 4.064 mm, and all passed the test.

[0058] By comparing the above experiments, grooves were made on the first coating to accommodate the adhesive layer, so as to improve the energy density of the battery cell while ensuring its safety performance.

[0059] The safety battery according to a second aspect of the present invention is characterized in that it includes a safety cell comprising any one of the above embodiments.

[0060] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A safety battery cell, characterized in that, include: A first electrode, a diaphragm, and a second electrode are sequentially stacked and wound into a core. The first electrode includes a current collector, a first coating, and an active material. The current collector includes a first region and a second region. The first region and the second region are arranged along the winding direction of the current collector. The first region is located at the end of the current collector winding and is exposed on the outside of the winding core. The first coating is located on the side of the first region opposite to the second electrode. The active material is located in the second region. The first coating has insulating properties. A groove is formed on the first coating along the thickness direction of the first electrode, and an adhesive layer is disposed in the groove. The adhesive layer protrudes from the first coating in the thickness direction of the first electrode and is used to fix the safety cell to the housing.

2. The safety battery cell according to claim 1, characterized in that, The first electrode further includes a second coating, which is conductive and disposed in a second region of the first electrode. The active material is disposed on the side of the second coating opposite to the current collector.

3. The safety battery cell according to claim 2, characterized in that, The first region also has the second coating on the side facing the second electrode.

4. The safety battery cell according to claim 1, characterized in that, The first electrode is a cathode.

5. The safety battery cell according to claim 1, characterized in that, The grooves are provided in multiple ways along the winding direction of the first electrode sheet.

6. The safety battery cell according to claim 1, characterized in that, The depth of the groove does not exceed the thickness of the first coating in the thickness direction of the first electrode. The thickness of the first coating outside the groove is H1, and the thickness of the first coating inside the groove is H2, where 0.3H1≤H2≤0.8H1.

7. The safety battery cell according to claim 1, characterized in that, The adhesive layer has a length of L1 in the width direction of the first electrode, and the groove has a length of L2 in the width direction of the first electrode, where L1≤L2≤L1+10mm.

8. The safety battery cell according to claim 7, characterized in that, The length of the adhesive layer in the winding direction of the first electrode is W1, and the length of the groove in the winding direction of the first electrode is W2, where W1≤W2≤W1+10mm.

9. The safety battery cell according to claim 2, characterized in that, The material of the second coating is lithium iron phosphate, and the material of the first coating is ceramic.

10. A safe battery, characterized in that, Includes the safety battery cell according to any one of claims 1-9.

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