Button cell

Abstract

Disclosed in the present application is a button cell, comprising: a positive electrode housing, the positive electrode housing comprising a support portion and a corner portion connected to the outer side of the support portion, wherein the corner portion comprises a first bend section having a first radius of curvature R1 and a second bend section having a second radius of curvature R2, and the second bend section is connected between the support portion and the first bend section; a negative electrode housing, which comprises a covering portion and a curved snap-fitting portion having a third radius of curvature R3, the covering portion and the support portion being arranged opposite each other; and a sealing sleeve, which is sandwiched between the corner portion and the curved snap-fitting portion so as to achieve sealing between the positive electrode housing and the negative electrode housing.

Description

button cell battery

[0001] This application claims priority to Chinese patent applications filed on December 31, 2024, with application number 2024233195809 and application number 2024119975026, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and more particularly to a button cell battery. Background Technology

[0003] Button batteries are widely used as power sources in various microelectronic products due to their lightweight and small size, such as smart cameras, digital cameras, and dashcams. A button battery mainly consists of a positive electrode casing, a negative electrode cap, and a cell and electrolyte within a sealed cavity formed between the positive and negative electrode casings. The positive electrode, separator, and negative electrode are stacked and folded in sequence to form the cell.

[0004] When batteries are used as memory power sources in applications such as smart cameras and dashcams, they require special packaging processes, such as reflow soldering. During this process, the battery must withstand temperatures exceeding 200°C (up to 260°C). However, ordinary lithium batteries cannot withstand temperatures above 200°C, as the internal electrolyte will decompose and produce gas under high temperatures. Technical issues

[0005] After the battery undergoes the reflow soldering process, the positive electrode casing and negative electrode cap in the relevant technologies are prone to deformation due to poor sealing, which can lead to leakage during later use. Technical solutions

[0006] This application provides a button cell battery, characterized in that it comprises:

[0007] A positive electrode shell includes a support portion and a corner portion connected to the outside of the support portion. The corner portion includes a first bend segment and a second bend segment. The second bend segment is connected between the support portion and the first bend segment. The first radius of curvature R1 of the first bend segment ranges from 0.5 to 0.85 mm, and the second radius of curvature R2 of the second bend segment ranges from 0.1 to 0.5 mm.

[0008] The negative electrode shell includes a cover portion and a bent fastening portion. The cover portion and the support portion are disposed opposite to each other. The bent fastening portion has a third radius of curvature R3, which is in the range of 0.1-0.3 mm. The area of ​​the bent fastening portion with the third radius of curvature R3 is disposed opposite to the first bend segment.

[0009] A sealing sleeve is sandwiched between the corner portion and the bent fastening portion to achieve a seal between the positive electrode shell and the negative electrode shell. Beneficial effects

[0010] By setting the first curvature radius R1 and the second curvature radius R2 of the first and second bend sections of the positive electrode shell in the range of 0.5-0.85mm and 0.1-0.5mm respectively, and setting the third curvature radius R3 of the bent fastening part of the negative electrode shell that cooperates with the first bend section in the range of 0.1-0.3mm, and sealing the corner and the bent fastening part with a sealing sleeve, after the button cell is assembled, the bent fastening part of the negative electrode shell can cooperate with the pressure of the first bend section and the second bend section respectively, pressing the sealing sleeve between the bent fastening part and the first bend section and between the bent fastening part and the second bend section, thereby ensuring the sealing performance of the button cell when subjected to high temperatures in the later stage. Attached Figure Description

[0011] Figure 1 is a schematic diagram of the first structure of a button battery according to an embodiment of this application;

[0012] Figure 2 is a second structural schematic diagram of the button cell in Figure 1;

[0013] Figure 3 is a partially enlarged schematic diagram of the button cell shown in Figure 1.

[0014] Attached Figure: 100-Button cell, 10-Positive electrode shell, 11-Support part, 12-Corner part, 121-First bend section, 122-Second bend section, 13-Placement groove, 20-Negative electrode shell, 21-Cover part, 22-Bent buckle part, 221-Third bend section, 222-Fourth bend section, 223-Fifth bend section, 23-First corner part, 24-Second corner part, 30-Sealing sleeve, 31-Card slot, 40-Negative electrode current collector, 50-Negative electrode sheet, 60-Separator, 61-Bent section, 70-Positive electrode sheet, 80-Positive electrode current collector, 90-Negative electrode conductive layer. Embodiments of the present invention

[0015] In the description of this application, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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 application.

[0016] Example 1

[0017] Please refer to Figures 1 to 3, which show the button cell 100 provided in the embodiments of this application, including a positive electrode shell 10, a negative electrode shell 20, and a sealing sleeve 30.

[0018] Referring to Figures 1 and 2, the positive electrode shell 10 includes a support portion 11 and a corner portion 12 connected to the outside of the support portion 11. The corner portion 12 includes a first bend segment 121 and a second bend segment 122. The second bend segment 122 connects the support portion 11 and the first bend segment 121. The first radius of curvature R1 of the first bend segment 121 ranges from 0.5 to 0.85 mm, and the second radius of curvature R2 of the second bend segment 122 ranges from 0.1 to 0.5 mm. The negative electrode shell 20 includes a cover portion 21 and a bent fastening portion 22. The cover portion 21 and the support portion 11 are disposed opposite to each other. The bent fastening portion 22 has a third radius of curvature R3, which ranges from 0.1 to 0.3 mm. The area of ​​the bent fastening portion 22 with the third radius of curvature R3 is disposed opposite to the first bend segment 121. The sealing sleeve 30 is sandwiched between the bend segment 12 and the bent fastening portion 22 to achieve a seal between the positive electrode shell 10 and the negative electrode shell 20.

[0019] The aforementioned button cell 100, by setting the first curvature radius R1 and the second curvature radius R2 of the first bend segment 121 and the second bend segment 122 of the positive electrode shell 10 in the range of 0.5-0.85mm and 0.1-0.5mm respectively, and setting the third curvature radius R3 of the bent fastening part 22 of the negative electrode shell 20 that cooperates with the first bend segment 121 in the range of 0.1-0.3mm, and sealing the corner part 12 and the bent fastening part 22 with a sealing sleeve 30, after the button cell 100 is assembled, the bent fastening part 22 of the negative electrode shell 20 can cooperate with the pressure of the first bend segment 121 and the second bend segment 122 respectively, pressing the sealing sleeve 30 between the bent fastening part 22 and the first bend segment 121 and between the bent fastening part 22 and the second bend segment 122, thereby ensuring the sealing performance of the button cell 100 when subjected to high temperature in the later stage.

[0020] Understandably, since the greater the curvature, the more curved the curve, and the smaller the curvature, the less curved the curve, and the reciprocal of curvature is the radius of curvature, therefore, the smaller the radius of curvature, the more curved the curve; and the greater the curvature, the less curved the curve.

[0021] If the first radius of curvature R1 of the positive electrode shell 10 exceeds 0.85mm, the degree of curvature at the first bend 121 is very small, which will lead to insufficient pressure, affecting the sealing performance between the positive electrode shell 10, the sealing sleeve 30 and the negative electrode shell 20. In addition, the height of the positive electrode shell 10 is prone to change, resulting in poor contact between the components inside the button cell. Therefore, the internal resistance of the button cell will increase after long-term use.

[0022] If the first radius of curvature R1R1 of the positive electrode shell 10 is less than 0.5mm, the degree of bending at the first bend 121 is very large, that is, the pressure on the sealing sleeve 30 is too large, which may cause the sealing sleeve 30 to crack, affecting the sealing performance of the button cell.

[0023] Since the second bending segment 122 is connected to the support portion 11, the end of the support portion 11 needs to undergo a large deformation to bend towards the negative electrode shell 20, forming a snap-fit ​​part from a straight state, thereby snapping into the negative electrode shell 20. Therefore, in order to ensure the magnitude of the snap-fit ​​force, i.e. to ensure the sealing performance, the radius of curvature of the first bending segment 121 is set to be greater than the radius of curvature of the second bending segment 122, i.e., the degree of bending of the first bending segment 121 is less than the degree of bending of the second bending segment 122. This not only realizes the deformation and bending of the positive electrode shell 10, but also enables the first bending segment 121 to snap into the bent snap-fit ​​portion 22.

[0024] Since the negative electrode shell 20 also needs to be bent from its original straight state to form the bent fastening part 22, the value of the third curvature radius R3 of the bent fastening part 22 is relatively small. That is, the negative electrode shell 20 is bent more, forming the third curvature radius R3 and the first bend segment 121 to cooperate with each other to compress the sealing sleeve 30.

[0025] In this embodiment, the positive electrode shell 10 and the negative electrode shell 20 can be made of stainless steel, such as SUS430, SUS304, or SUS316. The thickness H4 of the positive electrode shell 10 and the negative electrode shell 20 is in the range of 0.1-0.2 mm, which ensures structural strength and avoids a large battery thickness after manufacturing.

[0026] In normal use, the button cell 100, from the cover portion 21 to the support portion 11, also includes a negative electrode current collector 40, a negative electrode sheet 50, a separator 60, a positive electrode sheet 70, and a positive electrode current collector 80 stacked in sequence, as well as an electrolyte filled between the positive electrode shell 10 and the negative electrode shell 20. The separator 60 blocks the negative electrode sheet 50 and the positive electrode sheet 70. By setting the separator 60, the positive electrode sheet 70 and the negative electrode sheet 50 are prevented from connecting and short-circuiting during use. By setting the negative electrode current collector 40 and the current collector, the conductivity of the negative electrode sheet 50 and the positive electrode sheet 70 during the charging and discharging process is improved, and the internal resistance during the charging and discharging process is reduced.

[0027] The positive electrode sheet 70 includes a positive electrode foil and positive electrode active material, positive electrode conductive agent, and positive electrode binder coated on the positive electrode foil. The positive electrode active material can be lithium manganese oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium-rich manganese-based material, lithium manganese iron phosphate, etc. The mass of the positive electrode active material accounts for 80-95% of the total mass of all coated materials. The positive electrode conductive agent is mainly graphite, acetylene black, conductive carbon black, etc., accounting for 3-15% of the total mass of the coated materials. The positive electrode binder includes commonly used lithium battery positive electrode binders such as polytetrafluoroethylene (PTEF) and vinylidene fluoride (PVDF), accounting for 2%-15% of the total mass of all coated materials.

[0028] The negative electrode sheet 50 includes a negative electrode foil and a negative electrode active material, a conductive agent, and a binder coated on the negative electrode foil. The negative electrode active material can be materials such as silicon, silicon oxide, and silicon carbon, and the mass of the negative electrode active material accounts for 30-85% of the total mass of the coated materials. The main components of the negative electrode conductive agent are graphite, acetylene black, conductive carbon black, and graphite, and the proportion of the negative electrode conductive agent in the total mass of all coated materials is 10-50%. The negative electrode binder includes materials such as polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), and polyacrylate (LA), and the proportion of the negative electrode binder in the total mass of all coated materials is 2-15%.

[0029] Among them, the negative electrode current collector 40 and the positive electrode current collector 80 are composed of conductive slurries with graphite or acetylene black as fillers, and polyacrylate (LA), polyacrylic acid, polyamide imide (PAI) and other dispersants are used.

[0030] The separator 60 can be one of ceramic separator, cellulose separator, glass fiber, polyetheretherketone resin (PEEK), polyester film (PET), polyimide (PI), or polyamide (PA). In some embodiments, glass fiber in polyimide (PI) and polyamide (PA) is preferred because it has good high-temperature resistance and long charging cycle life.

[0031] The sealing sleeve 30 can be made of polyetheretherketone resin (PEEK), polyphenylene sulfide resin (PPS), polyamide resin (PA), etc. Among them, polyetheretherketone resin (PEEK), polyphenylene sulfide resin (PPS), and polyamide resin (PA) all have high thermoplasticity and good pressure resistance when subjected to pressure between the positive electrode shell 10 and the negative electrode cover 20, which can prevent it from being pressed and breakage and ensure the sealing performance of the battery after high temperature. One of them can be selected for use.

[0032] The electrolyte consists of a lithium salt and an organic solvent. The lithium salt can be at least one of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium bis(fluorosulfonamide)imide (LiFSI), lithium bis(trimethylmethylsulfonyl)imide (LiTFSI), and lithium tetrafluoroborate (LiBF4). The solvent can be at least one of propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dimethyl ethylene glycol (DME). The lithium salt concentration is 1-1.5 mol / L.

[0033] Referring to Figure 1, in one embodiment of this application, since the negative electrode conductive material is less conductive than the positive electrode material in the negative electrode system, the coin cell 100 further includes a negative electrode conductive layer 90 to ensure the charging and discharging stability of the negative electrode side. The negative electrode conductive layer 90 is disposed between the negative electrode sheet 50 and the separator 60. The negative electrode conductive layer 90 enhances the performance of the negative electrode sheet 50 during charging and discharging, preventing the battery from experiencing increased ion migration efficiency due to increased impedance after long-term use. The material of the negative electrode conductive layer can be graphite, acetylene black, or similar materials. It is understood that a positive electrode conductive layer can also be added to the positive electrode side to increase the battery's charging and discharging performance; this is not limited here.

[0034] When setting the diaphragm 60, the sealing sleeve 30 is provided with a groove 31, and the free end of the diaphragm 60 is a bent section 61, which is locked in the groove 31. In this way, by setting the groove 31 in the sealing sleeve 30, the setting position of the diaphragm 60 can be limited, preventing the diaphragm 60 from shifting, so that the diaphragm 60 can block the positive electrode 70 and the negative electrode 50, and prevent short circuit between the positive electrode 70 and the negative electrode 50.

[0035] Referring to Figures 1-3, the curved fastening part 22 includes a third bend segment 221, a fourth bend segment 222, and a fifth bend segment 223 connected in sequence. The third bend segment 221 connects to the cover part 21 and has a third radius of curvature R3. The fourth bend segment 222 bends towards the diaphragm 60, and the fifth bend segment 223 bends away from the diaphragm 60. The distance Z2 between the fifth bend segment 223 and the first bend segment 121 ranges from 0.15 to 0.4 mm. The end of the fifth bend segment 223... The distance Z3 between the end and the inner wall of the support 11 is in the range of 0.15-0.4mm, that is, the sealing sleeve 30 is sandwiched between the negative electrode shell 20 and the positive electrode shell 10 and is in a compressed state. By matching the values ​​of Z3 and Z2, it is ensured that the sealing sleeve 30 is in a sufficient compression between the positive electrode shell 10 and the negative electrode shell 20, so as to avoid leakage when the compression of the sealing sleeve 30 is insufficient, and to avoid deformation of the negative electrode shell 20 when the compression of the sealing sleeve 30 is too large during battery installation.

[0036] The values ​​of Z2 and Z3 can be set to be the same or different.

[0037] Please refer to Figures 1 to 3. In one embodiment of this application, in order to facilitate the placement of the positive electrode material, the support part 11 is provided with a placement groove 13. The positive electrode current collector 80 is placed in the placement groove 13. Since the button cell is installed in an upside-down manner, that is, the negative electrode shell 20 is placed upside down on the support surface, and the negative electrode current collector 40, negative electrode sheet 50, negative electrode conductive layer 90, separator 60, positive electrode sheet 70 and positive electrode current collector 80 are set in sequence. Then the sealing sleeve 30 is placed on the negative electrode shell 20 and the separator 60, and finally the positive electrode shell 10 is covered. In this way, by providing the placement groove 13 on the positive electrode shell 10, the positive electrode sheet 70 can be quickly positioned in the installation position of the positive electrode shell 10, improving the installation efficiency.

[0038] In some embodiments, the placement groove 13 is formed by a portion of the support portion 11 protruding away from the cover portion 21. That is, when forming the placement groove 13, an external force can be used to bend the positive electrode shell 10, so that a portion of the positive electrode shell 10 deforms to form the placement groove 13. This not only facilitates the setting of the placement groove 13 and has high forming efficiency, but also ensures the structural strength of the positive electrode shell 10. In other embodiments, the placement groove 13 can be formed by slotting inside the body of the positive electrode shell 10, which can also achieve the setting of the placement groove 13.

[0039] In some embodiments, please refer to Figure 2. When the placement groove 13 is formed, the width D1 of the placement groove 13 is 75-85% of the width D of the battery. By setting this value, the electrode and current collector with sufficient width can be set to ensure the power supply. This avoids wasting installation space when the width is set too small, which would also lead to insufficient battery power supply. It also avoids inconvenience in assembly in the equipment when the width ratio is set too large.

[0040] In this embodiment, the width D of the button cell is in the range of 4-12mm. For example, when the width D of the button cell is set to 4mm, and the width D1 of the placement slot 13 is 80% of the width D of the cell, the value of D1 is 4mm*80%=3.2mm.

[0041] Referring to Figure 2, the height H3 of the placement slot 13 is set to a range of 0.1-0.3 mm. This height setting mitigates the height changes of the coin cell during charging and discharging, providing expansion space for the coin cell at higher temperatures and during charging and discharging. This range avoids both insufficient movement of the internal electrodes when the height is too small and insufficient clamping between internal structures and increased internal resistance when the height is too large, which could lead to poor contact between internal structures during charging and discharging and affect charging and discharging performance.

[0042] In some embodiments, please refer to Figure 2. The height of the button cell 100 is H, the distance between the first bend segment 121 and the bottom of the support portion 11 is H2, and the range of H2+H3 is 80%-90% of the height H. By setting this height, the second bend segment 122 has sufficient extension length to be pressed against the sealing sleeve 30, ensuring the tightness of the sealing sleeve 30. At the same time, a larger number of sealing sleeves 30 can be set to achieve a sealing effect.

[0043] In some embodiments, the height H of the button cell 100 in this embodiment ranges from 1 to 5 mm. For example, in some embodiments, the button cell H=5 mm, H2=4 mm, and H3=0.3 mm. In this case, H2+H3=4.3 mm, and (H2+H3) / H*100%=86%. 86% is within the range of 80%-90%, which meets the requirements.

[0044] The manufacturing process of the above battery is as follows:

[0045] (1) Prepare the positive electrode shell 10 and the negative electrode shell 20;

[0046] (2) Apply a layer of first conductive adhesive and a layer of second conductive adhesive to the inner surfaces of the positive electrode shell 10 and the negative electrode shell 20 respectively, and dry the first conductive adhesive and the second conductive adhesive. The dried first conductive adhesive and the second conductive adhesive become the positive electrode current collector 80 or the negative electrode current collector 40.

[0047] (3) Coat one side of the negative electrode 50 with a third conductive adhesive and dry the third conductive adhesive so that the dried third conductive adhesive can be used as the negative electrode current collector 40.

[0048] (4) Invert the negative electrode shell 20 and place the negative electrode sheet 50 and the diaphragm 60 in the negative electrode shell 20 in sequence, with the diaphragm 60 corresponding to the side of the negative electrode sheet 50 where the negative electrode current collector 40 is located.

[0049] (5) Cover the negative electrode shell 20 and the diaphragm 60 with the sealing sleeve 30;

[0050] (6) Place the positive electrode 70 on the separator 60;

[0051] (7) Cover the positive electrode shell 10 over the negative electrode shell 20 and the sealing sleeve 30, and apply pressure to the positive electrode shell 10 to complete the assembly of the entire button cell.

[0052] Thus, by setting the parameters of the first radius of curvature R1, the second radius of curvature R2, the third radius of curvature R3 on the negative electrode shell 20, and the thicknesses of the sealing sleeve 30 Z2 and Z3, the button battery 100 of this embodiment can have good sealing performance after high-temperature testing, which can prevent the button battery 100 from leaking, and at the same time avoid external moisture from entering the battery and causing battery performance degradation, thereby improving the battery's service life.

[0053] The aforementioned button cell 100, by setting the radii of curvature of the first bend 121 and the second bend 122 of the positive electrode shell 10 in the ranges of 0.5-0.85mm and 0.1-0.5mm respectively, and setting the third radius of curvature R3 of the negative electrode shell 20 in the range of 0.1-0.3mm, ensures the sealing performance of the button cell 100 when subjected to high temperatures later by setting the curvature radii of curvature of the negative electrode shell 20 and the separator 60 together with the pressure of the first bend 121 and the second bend 122 respectively after the button cell 100 is assembled. A negative conductive layer 90 is also provided to ensure the conductivity of the negative electrode side and resist the impedance generated by the button cell after long-term use. By setting the height range of the two positions of the sealing sleeve 30 within the range of 0.15-0.4mm, the compression of the sealing sleeve 30 is ensured, thereby ensuring the sealing performance. By setting the placement groove 13 on the positive electrode shell 10, it is easy to position the positive electrode sheet 70 during assembly, thereby improving the installation efficiency. By setting the overall height H2+H3 of the positive electrode shell 10 within the range of 80%H-90%H of the total battery height H, the second bend section 122 has sufficient extension length to press against the outside of the sealing sleeve 30, ensuring the tightness of the sealing sleeve 30, and at the same time, a larger number of sealing sleeves 30 can be set to achieve the sealing effect.

[0054] Therefore, within the above range, the battery still has good sealing performance even after high-temperature testing, which can prevent electrolyte leakage and evaporation, or external moisture from entering the battery and causing battery performance degradation.

[0055] Example 2:

[0056] This embodiment provides a button cell 100 prepared using the above-described parameters and manufacturing method, specifically:

[0057] (1) The diameter D of the button cell 100 is 6.8 mm, the height H is 2.1 mm, H2 is 1.5 mm, H3 is 0.2 mm, R1 is 0.75 mm, the compression Z2 of the sealing sleeve 30 between the first bend 121 and the fifth bend 2412 is 0.35 mm, and the compression Z3 of the sealing sleeve 30 between the end of the negative electrode shell 20 and the support part 11 of the positive electrode shell 10 is 0.3 mm;

[0058] (2) In the positive electrode sheet 70, lithium manganese oxide is used as the positive electrode active material, graphite is used as the positive electrode conductive agent, and polyacrylic acid is used as the positive electrode binder. They are mixed in a weight ratio of 90:8:2. 95.3 mg of the mixed powder is pressed into a disc with a diameter of 3.8 mm. This disc is used as the positive electrode sheet 70 for subsequent battery assembly.

[0059] (3) The negative electrode 50 uses silicon oxide as the negative electrode active material, graphite as the negative electrode conductive agent, and polyacrylic acid as the negative electrode binder. They are mixed in a weight ratio of 70:28:2. 5.1 mg of the mixed powder is pressed into a disc with a diameter of 3.8 mm. This disc is used as the negative electrode 50 for subsequent battery assembly.

[0060] (4) The electrolyte is 1 mol / L lithium bisfluorosulfonylimide (LiFSI), and the solvent is a mixture of propylene carbonate (PC), ethylene carbonate (EC), and dimethyl ethylene glycol (DME) in a weight ratio of 1:1:2.

[0061] (5) The diaphragm 60 is made of polyimide (PI), and the sealing sleeve 30 is made of polyphenylene sulfide resin (PPS).

[0062] Comparative Example 1:

[0063] Comparative Example 1 provides a button cell 100 manufactured according to the above method, but some parameters of the positive electrode shell 10 or the negative electrode shell 20 are different from those in Example 2, wherein:

[0064] (1) The diameter D of the button cell 100 is 6.8 mm, the height H is 2.1 mm, H2 is 1.5 mm, H3 is 0.2 mm, R1 is 0.5 mm (less than R1 in Example 2), R2 is 0.75 mm, the compression Z2 of the sealing sleeve 30 between the first bend segment 121 and the fifth bend segment 2412 is 0.3 mm (less than Z2 in Example 2), and the compression Z3 of the sealing sleeve 30 between the end of the negative electrode shell 20 and the support portion 11 of the positive electrode shell 10 is 0.25 mm (less than Z3 in Example 2).

[0065] (2) In the positive electrode 70, lithium manganese oxide is used as the positive electrode active material, graphite is used as the positive electrode conductive agent, and polyacrylic acid is used as the positive electrode binder. They are mixed in a weight ratio of 90:8:2. 95.3 mg of the mixed powder is pressed into a disc with a diameter of 3.8 mm. The disc is used as the positive electrode 70 for battery assembly.

[0066] (3) The negative electrode 50 uses silicon oxide as the negative electrode active material, graphite as the negative electrode conductive agent, and polyacrylic acid as the negative electrode binder. They are mixed in a weight ratio of 70:28:2. 5.1 mg of the mixed powder is pressed into a disc with a diameter of 3.8 mm. This disc is used as the negative electrode 50 for subsequent battery assembly.

[0067] (4) The electrolyte is 1 mol / L lithium bisfluorosulfonylimide (LiFSI), and the solvent is a mixture of propylene carbonate (PC), ethylene carbonate (EC), and dimethyl ethylene glycol (DME) in a weight ratio of 1:1:2.

[0068] Comparative Example 2:

[0069] Comparative Example 2 provides a button cell 100 manufactured according to the above method, but some parameters of the positive electrode shell 10 or the negative electrode shell 20 are different from those in Example 2, wherein:

[0070] (1) The diameter D of the buckle is 6.8 mm, the height H is 2.1 mm, H2 is 1.7 mm (greater than H2 in Example 2), H3 is 0.2 mm, R1 is 0.85 mm (greater than R1 in Example 1), the compression amount Z2 of the sealing sleeve 30 between the first bend segment 121 and the fifth bend segment 2412 is 0.35 mm, and the compression amount Z3 of the sealing sleeve 30 between the end of the negative electrode shell 20 and the support portion 11 of the positive electrode shell 10 is 0.3 mm;

[0071] (2) The positive electrode 70 uses lithium manganese oxide as the positive electrode active material, graphite as the positive electrode conductive agent, and polyacrylic acid as the positive electrode binder. They are mixed in a weight ratio of 90:8:2. 95.3 mg of the mixed powder is pressed into a disc with a diameter of 3.8 mm. This disc is used as the positive electrode 70 for subsequent battery assembly.

[0072] (3) The negative electrode sheet 50 uses silicon oxide as the negative electrode active material, graphite as the negative electrode conductive agent, and polyacrylic acid as the negative electrode binder. After mixing them in a weight ratio of 70:28:2, 5.1 mg of the mixed powder is pressed into a disc with a diameter of 3.8 mm. This disc is used as the negative electrode sheet 50 for subsequent battery assembly.

[0073] (4) The electrolyte is 1 mol / L lithium bisfluorosulfonylimide (LiFSI), and the solvent is a mixture of propylene carbonate (PC), ethylene carbonate (EC), and dimethyl ethylene glycol (DME) in a weight ratio of 1:1:2.

[0074] (5) The diaphragm 60 is made of polyimide (PI), and the sealing material is made of polyphenylene sulfide resin (PPS).

[0075] Furthermore, the button cell 100 prepared in Example 2, Comparative Example 1, and Comparative Example 2 were tested using the same temperature and charge / discharge test methods:

[0076] (1) Discharge the button cell 100 at room temperature so that the capacity is the initial capacity Q0, and record the height H and internal resistance of the button cell 100 at the same time.

[0077] (2) After the button cell 100 has passed the temperature of the reflow soldering process, the height H and internal resistance are tested. At the same time, the discharge capacity of the button cell 100 after the reflow soldering process is recorded as capacity Q. The reflow soldering process conditions are: the button cell 100 is kept at 160℃ for 10 min and then kept at 260℃ for 30 s.

[0078] (4) Calculate the capacity retention rate of the 100-cell button cell: Capacity retention rate = Discharge capacity after reflow soldering / Initial discharge capacity = Q / Q0 x 100%;

[0079] (5) After the reflow soldering test of the button cell 100, observe whether there is liquid seepage on the surface of the button cell 100. At the same time, compare the height H and internal resistance of the button cell 100 before and after reflow soldering. The change in height = the initial height H of the button cell 100 - the final height H of the button cell 100 after reflow soldering.

[0080] Among these, a capacity retention rate of over 90% can be considered as no significant change in battery performance; an internal resistance change of within 50Ω is acceptable; and a height H change of 100mm for coin cells is within the standard range.

[0081] The parameters of the button cells 100 prepared in Example 2, Comparative Example 1, and Comparative Example 2 are compared as follows:

[0082]

[0083] (1) The values ​​of H2, R1, R2, R3, Z2, and Z3 of the button cell 100 in Example 2 are within the optimal range listed in Example 1. The change in internal resistance of the battery before and after reflow soldering is small (Δ=420-408=12Ω), and the button cell 100 shows no obvious liquid leakage, indicating that the button cell 100 still has good sealing performance after high temperature treatment. At the same time, the capacity retention rate of the button cell 100 is above 90%, which can meet the capacity requirements of the button cell 100.

[0084] (2) Compared with Example 2, H2 in Comparative Example 1 is lower than the preferred range, that is, the bending extension length of the positive electrode shell 10 for sealing is insufficient, and R1 is 0.5mm. Although it is smaller than R1 in Example 2, it is within the preferred range. After the reflow soldering process, liquid appears on the surface of the button cell 100. Therefore, the reason may be that the pressure of the first bend section 121 of the positive electrode shell 10 is too large during the sealing process of the button cell 100, which may crack the sealing sleeve 30, thereby affecting the thermoplasticity of the sealing sleeve 30, causing the electrolyte inside the button cell 100 to leak or external moisture to enter the button cell 100, resulting in an increase in the internal resistance of the button cell 100 and a decrease in the capacity retention rate.

[0085] (3) In Comparative Example 2, the distance between the end of the first bend 121 in the button cell 100 and the outer wall of the support 21 exceeds the preferred range. When R2 is 0.75mm, which is greater than the optimal preferred value of R2 0.5, there is no obvious liquid seepage on the surface of the button cell 100, but the internal resistance changes too much. It may be that the large H2 causes poor contact inside the button cell 100. The increased internal resistance of the battery will also cause the battery capacity retention rate to be less than 90%.

[0086] In summary, the test results of Example 2 and Comparative Examples 1 and 2 respectively show that the button cell 100 prepared according to the parameters of the first radius of curvature R1, the second radius of curvature R2, the third radius of curvature R3 on the negative electrode shell 20, and Z2 and Z3 of the sealing sleeve 30 still has good sealing performance after being subjected to high temperature environment, which can prevent leakage. At the same time, the electrical performance of the button cell 100 does not deteriorate significantly, thus ensuring the performance of the button cell 100.

Claims

1. A button cell battery (100), comprising: A positive electrode shell (10) includes a support portion (11) and a corner portion (12) connected to the outside of the support portion (11). The corner portion (12) includes a first bend segment (121) and a second bend segment (122). The second bend segment (122) is connected between the support portion (11) and the first bend segment (121). The first radius of curvature R1 of the first bend segment (121) is in the range of 0.5-0.85mm, and the second radius of curvature R2 of the second bend segment (122) is in the range of 0.1-0.5mm. The negative electrode shell (20) includes a cover portion (21) and a bent fastening portion (22). The cover portion (21) and the support portion (11) are disposed opposite to each other. The bent fastening portion (22) has a third radius of curvature R3. The range of the third radius of curvature R3 is 0.1-0.3 mm. The area of ​​the bent fastening portion (22) with the third radius of curvature R3 is disposed opposite to the first bend segment (121). A sealing sleeve (30) is sandwiched between the corner portion (12) and the bent fastening portion (22) to achieve a seal between the positive electrode shell (10) and the negative electrode shell (20).

2. The button cell (100) according to claim 1, wherein, From the cover portion (21) toward the support portion (11), the button cell (100) further includes a negative electrode current collector (40), a negative electrode sheet (50), a separator (60), a positive electrode sheet (70), and a positive electrode current collector (80) stacked in sequence, with the separator (60) separating the negative electrode sheet (50) and the positive electrode sheet (70).

3. The button cell (100) according to claim 2, wherein, The coin cell (100) further includes a negative electrode conductive layer (90), which is disposed between the negative electrode sheet (50) and the separator (60).

4. The button cell (100) according to claim 2 or 3, wherein, The sealing sleeve (30) is provided with a groove (31), and the free end of the diaphragm (60) is a curved section, which is engaged in the groove (31).

5. The button cell battery according to claim 4, wherein, The curved fastening part (22) includes a third bend section (221), a fourth bend section (222), and a fifth bend section (223) connected in sequence. The third bend section (221) is connected to the cover part (21) and has the third radius of curvature R3. The fourth bend section (222) bends toward the diaphragm (60), and the fifth bend section (223) bends away from the diaphragm (60). The distance Z2 between the fifth turning segment (223) and the first turning segment (121) ranges from 0.15 to 0.3 mm. The distance Z3 between the end of the fifth bend (223) and the inner wall of the support (11) ranges from 0.15 to 0.4 mm.

6. The button cell (100) according to claim 2 or 3, wherein, The support part (11) is provided with a placement groove (13), and the positive current collector (80) is placed in the placement groove (13).

7. The button cell (100) according to claim 6, wherein, The placement groove (13) is formed by a portion of the support portion (11) protruding in a direction away from the cover portion (21).

8. The button cell (100) according to claim 6, wherein, The width D1 of the placement slot (13) is 75%-85% of the width D of the battery.

9. The button cell (100) according to claim 7 or 8, wherein, The height H3 of the placement slot (13) ranges from 0.1 to 0.3 mm.

10. The button cell (100) according to claim 9, wherein, The height of the button cell (100) is H, the distance between the bottom of the first bend segment (121) and the support segment is H2, and the range of H2+H3 is 80%-90% of the height H.

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