Battery

Abstract

The invention relates to the technical field of batteries, in particular to a battery. Comprising a metal shell, the metal shell is provided with a lead-out wall surface, a battery cell is arranged in a containing cavity, the battery cell comprises a positive plate, a negative plate and a diaphragm which are stacked, and a positive tab is provided with a stacked section, a bent section and a connecting section in the extending direction of the positive tab; the negative plate comprises a negative current collector, a negative active layer positioned on the negative current collector and a negative tab formed by extending outwards from one side edge of the negative current collector; the mass content of the element silicon in the negative electrode active layer is 5-60%; the adapter comprises a first part, a second part and a bending part for connecting the first part and the second part; the bent part of the adapter is at least partially covered with an insulating part, and the insulating part is located on the surface of the side, away from the connecting section, of the bent part. The battery provided by the invention can prevent short circuit caused by contact between the adapter and the metal shell.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a battery. Background Technology

[0002] As the energy density of pouch lithium-ion batteries approaches its design limit, metal-packaged batteries can further improve energy density compared to pouch batteries.

[0003] Currently, metal-cased batteries are continuously improving their energy density, and the space utilization of the positive electrode tab is getting higher and higher. This also poses new challenges to the insulation between the positive electrode and the casing, especially the safety in drop and tumbling tests, which requires special attention. Summary of the Invention

[0004] To address the aforementioned technical problems in the prior art, the present invention provides a battery. The battery of the present invention avoids the risk of short circuits caused by contact between the positive electrode tab and the metal casing, which is prone to occur during drop tests or cycling of cells containing silicon-doped negative electrodes.

[0005] This invention provides a battery, comprising: a metal casing having a receiving cavity, the metal casing having a lead-out wall surface with a through hole communicating with the receiving cavity; a battery cell disposed within the receiving cavity, the battery cell comprising a positive electrode plate, a negative electrode plate, and a separator stacked thereon, the positive electrode plate comprising a positive electrode current collector and a positive electrode tab extending outward from one side edge of the positive electrode current collector; the positive electrode tab having a stacked section, a bent section, and a connecting section along its extending direction; the negative electrode plate comprising a negative electrode current collector, a negative electrode active layer on the negative electrode current collector, and a negative electrode tab extending outward from one side edge of the negative electrode current collector; the negative electrode tab and... The metal casing has lead-out wall connections; the negative electrode active layer contains 5%-60% silicon by mass; an electrode assembly is inserted into a through hole; an adapter includes a first part connected to a connecting section of the positive electrode tab, a second part connected to the electrode assembly, and a bent portion connecting the first and second parts, the bent portion being bent away from the connecting section, and the connecting section of the positive electrode tab being located between the first and second parts along the length of the metal casing; the bent portion of the adapter is at least partially covered with an insulating element, the insulating element being located on the side surface of the bent portion away from the connecting section.

[0006] By employing the above technical solution, the present invention has at least the following advantages compared with the prior art:

[0007] Understandably, during charging, the silicon-doped negative electrode sheet expands by 200-300%, leading to significant expansion of the entire cell (and even the positive and negative electrode tabs). This can easily cause the positive electrode tab connector to collide with the metal casing, resulting in a short circuit. Furthermore, during battery drop tests, the cell is subjected to the force of the drop, causing the connector to shift, with the positive electrode tab and sidewall exhibiting opposite deformation directions. The bending point of the connector is particularly close to the metal casing, posing a high risk of short circuit due to contact between the positive electrode tab and sidewall. The battery of this invention addresses this by at least partially covering the bent portion of the connector with an insulating element, effectively creating an insulating barrier between the metal casing and the bent portion of the connector. Even if the force experienced during a drop test, or the expansion force of the silicon-doped negative electrode cell during charging and discharging, causes contact between the connector and the metal casing, the insulating element prevents direct contact and short circuits.

[0008] Other features and advantages of the present invention will be described in detail in the following detailed description section.

[0009] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Attached Figure Description

[0010] To more clearly illustrate the specific embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0011] Figure 1 This is a front view of the battery in an embodiment of the present invention;

[0012] Figure 2 This is a partial structural detail diagram of the battery in an embodiment of the present invention;

[0013] Figure 3 This is an exploded view of a partial structure of the battery in an embodiment of the present invention;

[0014] Figure 4 This is a partial cross-sectional view of the battery structure in an embodiment of the present invention;

[0015] Figure 5This is a structural diagram of the adapter and insulating component in an embodiment of the present invention.

[0016] Explanation of reference numerals in the attached figures:

[0017] 1: Battery;

[0018] 100: Metal casing; 111: Receiving cavity; 112: Lead-out wall; 113: Through hole; 114: Bottom shell; 115: Cover plate; 116: Flange;

[0019] 200: Battery cell; 210: Positive electrode tab; 211: Lamination section; 212: Bending section; 213: Connecting section;

[0020] 300: Terminal assembly; 310: Outer insulating pad; 311: Perforation; 320: Inner insulating pad; 330: Terminal body; 340: Connecting piece;

[0021] 400: Adapter; 410: First part; 420: Second part; 430: Bent part;

[0022] 500: Insulating component. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0025] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0026] See Figure 1-5An embodiment of the present invention provides a battery 1, which includes a metal casing 100, a receiving cavity 111, a lead-out wall 112, and a through hole 113 in the lead-out wall 112, which communicates with the receiving cavity 111.

[0027] In a specific example, please refer to Figure 1 and Figure 2 The metal housing 100 includes a bottom shell 114 and a cover plate 115. The lead-out wall 112 is located on one side wall of the bottom shell 114. The bottom shell 114 has a flange edge forming on the edge facing the cover plate 115, and the cover plate 115 has a flange edge forming on the edge facing the bottom shell 114. The bottom shell and the flange edge and the flange edge of the cover plate are aligned and welded to seal the receiving cavity 111.

[0028] In one specific example, the metal casing 100 is made of materials such as steel, aluminum, or aluminum-plastic film. In other embodiments, the metal casing 100 may be irregularly shaped such as square, trapezoidal, polygonal, L-shaped, cylindrical, or arc-shaped.

[0029] See Figure 4 In this embodiment, the battery 1 further includes a cell 200 disposed in the receiving cavity 111. The cell 200 includes a positive electrode sheet, a negative electrode sheet and a separator stacked together. The positive electrode sheet includes a positive current collector, a positive electrode tab 210 extending outward from one side edge of the positive current collector, and a positive active layer located on the positive current collector. The negative electrode sheet includes a negative current collector, a negative active layer located on the negative current collector, and a negative electrode tab extending outward from one side edge of the negative current collector. The negative electrode tab is connected to the lead-out wall 112 of the metal casing 100.

[0030] In some embodiments, the battery cell may be a wound core formed by stacking and winding a positive electrode, a separator, and a negative electrode; in other embodiments, the battery cell may be a stacked core formed by stacking a positive electrode, a separator, and a negative electrode. In a further embodiment, the stacked core includes a top layer and a bottom layer of electrodes along the thickness direction, the top layer and / or the bottom layer of electrodes may be a single-sided negative electrode, the single-sided negative electrode including a negative current collector and a negative active layer on the surface of the negative current collector near the center of the battery cell. In other embodiments, the thickness of the current collector of the top layer electrode is greater than the thickness of the current collector of the same polarity electrodes in the middle of the stacked core, to prevent the top layer electrode from warping due to uneven stress during charging and discharging caused by the presence of an active layer on one side.

[0031] In a specific example, the positive current collector may be, for example, aluminum foil, aluminum alloy foil, or composite current collector (e.g., aluminum-carbon composite current collector), and the thickness of the positive current collector may be, for example, 6μm-15μm (e.g., 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, or 15μm).

[0032] In a specific example, the positive electrode active layer may include a positive electrode active material, such as lithium nickel cobalt manganese oxide (LiNi). 0.90 Co 0.05 Mn 0.05 At least one of the following: O2 (NCM955), NCM811, NCM622, NCM523, NCM111, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide (LiCoO2), lithium iron silicate, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel-type lithium manganese oxide, spinel-type lithium nickel manganese oxide, and lithium titanate.

[0033] In one specific example, the negative electrode current collector may be, for example, copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a composite current collector. In one example, the thickness of the negative electrode current collector may be, for example, 4μm-10μm (e.g., 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, or 10μm).

[0034] In one specific example, the separator includes a base membrane and adhesive layers on both sides of the base membrane. In a further embodiment, a ceramic layer and an adhesive layer are sequentially formed on a first side of the base membrane, and an adhesive layer is formed on a second side. The first side surface of the base membrane is disposed opposite to the positive electrode, and the second side surface of the base membrane is disposed opposite to the negative electrode. In some embodiments, the thickness of the separator is 5 μm-20 μm (e.g., 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, or 20 μm).

[0035] In one specific example, the battery also includes an electrolyte comprising a lithium salt and a solvent, wherein the solvent comprises at least one selected from ethylene carbonate, diethyl carbonate, or fluoroethylene carbonate. In another embodiment, the electrolyte further includes a nitrile additive. The nitrile additive content is C3 based on the total mass of the electrolyte. C3 is 0.5%-8%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, or 8%. In some embodiments, the nitrile additive includes, for example, at least one selected from butadionitrile, adiponitrile, and 1,3,6-hexanetrionitrile.

[0036] In one specific example, the negative electrode active layer may include a negative electrode active material, such as at least one selected from graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, spherical silicon-carbon, bulk silicon-carbon, Li-Al alloys, and metallic lithium. In embodiments where the negative electrode active material layer includes a silicon-carbon composite, the mass content of elemental silicon in the negative electrode active layer is 5%-60% (e.g., 5%, 5.5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%).

[0037] See Figure 3 and Figure 4 In this embodiment, multiple positive electrode tabs 210 are stacked sequentially to form a convergence portion, which is bent along the direction close to the bottom wall of the bottom shell 114 to form a stacked section 211, a bent section 212, and a connecting section 213 along its extension direction. That is, the positive electrode tabs 210 present a U-shaped structure, thereby improving the utilization rate of the head space of the metal shell 100. For example, the stacked section 211 and the connecting section 213 are approximately parallel to each other, thereby maximizing the utilization rate of the head space of the metal shell 100.

[0038] Please see Figures 2 to 4 In this embodiment, the battery 1 also includes a terminal assembly 300, which is disposed in the through hole 113; the terminal assembly 300 and the positive electrode tab 210 are electrically connected, thereby leading the current of the positive electrode out to the outside of the metal casing 100.

[0039] Please continue reading. Figures 1-3 The electrode assembly 300 includes insulating pads located on opposite inner and outer sides of the lead-out wall 112. For ease of description, the insulating pads located on opposite inner and outer sides of the lead-out wall 112 can be defined as outer insulating pad 310 and inner insulating pad 320. Both the inner insulating pad 320 and the outer insulating pad 310 are provided with through holes 311 corresponding to the through holes 113. It should be noted that the inner and outer sides defined in this embodiment are relative to the receiving cavity 111. Exemplarily, the side located within the receiving cavity 111 is called the inner side, and the side located outside the receiving cavity 111 is called the outer side.

[0040] The pole assembly 300 also includes a pole body 330 and a connecting piece 340. The pole body 330 passes through the outer insulating pad 310, the through hole 113 and the inner insulating pad 320 and is connected to the connecting piece 340. In a specific example, the pole body 330 includes a straight portion and an insertion portion extending outward from the straight portion. The insertion portion passes through the through hole 113 and is connected to the connecting piece 340.

[0041] In another specific example, the terminal assembly 300 includes a terminal body and an insulating adhesive layer. The terminal body includes a straight portion and an insertion portion extending outward from the straight portion. The insertion portion passes through a through hole and connects to the positive electrode tab. The straight portion of the terminal body is located outside the metal casing and is bonded to the lead-out wall of the metal casing through the insulating adhesive layer. In this specific example, when the battery is under abnormal high-temperature conditions, the insulating adhesive layer melts at high temperatures, allowing gas to be released through the melted insulating adhesive layer.

[0042] Please see Figure 4 and Figure 5 In this embodiment, the battery 1 further includes an adapter 400, which includes a first part 410 connected to the connecting section 213 of the positive electrode tab 210, a second part 420 connected to the electrode post assembly 300, and a bent part 430 connecting the first part 410 and the second part 420. The bent part 430 is bent in a direction away from the connecting section 213. The second part 420 of the adapter 400 is connected to the connecting piece 340. That is to say, the adapter 400 can also be U-shaped.

[0043] Along the length of the metal casing 100, the connecting segment 213 of the positive electrode tab 210 is located between the first part 410 and the second part 420; the first part 410 of the adapter 400 is located between the connecting segment 213 of the positive electrode tab 210 and the stacked segment 211. Along the extending direction of the metal casing 100, the connection positions of the adapter 400 and the connecting piece 340 do not overlap with the projections of the connection positions of the adapter 400 and the positive electrode tab 210, thus utilizing the head space of the metal casing 100. It should be noted that the extending direction of the metal casing 100 can be understood as the length direction of the metal casing 100, or it can be understood as the direction in which the cell 200 points perpendicularly to the electrode assembly 300. Figures 1 to 3 Taking the orientation shown as an example, the extension direction of the metal casing 100 is the X direction shown in the figure above.

[0044] Please see Figure 3 In this embodiment, at least a portion of the bent portion 430 of the adapter 400 is covered by an insulating member 500, which is located on the side surface of the bent portion 430 facing away from the connecting section 213. Figure 3 Taking the orientation shown as an example, the insulating element 500 is located on the outer surface of the bent portion 430.

[0045] Understandably, in the existing technology, the silicon-doped negative electrode sheet expands by 200-300% during charging, which in turn causes the cell 200 (and even the positive and negative electrode tabs) to expand dramatically. This can easily lead to a short circuit caused by a collision between the adapter 400 and the metal casing 100 of the battery 1. Moreover, during the battery drop test, the cell 200 is subjected to the force of the drop, and the adapter 400 will move around. The deformation directions of the positive electrode tab 210 and the sidewall of the metal casing 100 tend to be opposite. In particular, the bending position of the adapter 400 is closest to the metal casing 100, which also poses a high risk of a short circuit due to contact between the positive electrode tab 210 and the metal casing 100. The battery 1 provided by the present invention has an insulating member 500 covering at least part of the bent portion 430 of the adapter 400. This is equivalent to setting an insulating barrier between the metal shell 100 and the bent portion 430 of the adapter 400. Even if the adapter 400 and the metal shell 100 come into contact due to the force of the drop test or the expansion force of the silicon-doped negative electrode cell 200 during the charging and discharging process, the insulating member 500 will block the contact, thereby preventing the adapter 400 and the metal shell 100 from directly contacting each other and causing a short circuit. Furthermore, due to the presence of the insulating member 500, the force of the drop test or the expansion force of the silicon-doped negative electrode cell 200 during the charging and discharging process can be effectively absorbed, preventing the adapter 400 from being subjected to excessive force and breaking due to excessive bending.

[0046] In a specific example, the insulating element 500 may be, for example, an adhesive layer or adhesive tape. Specifically, it can be formed on the outer surface of the adapter 400 by applying adhesive or attaching adhesive; alternatively, the insulating element 500 can also be thermally bonded to the adapter 400 by lamination. In this way, the insulating element 500 can be uniformly and seamlessly covered, ensuring a tight fit between the insulating element 500 and the adapter 400, thereby improving the insulation capability of the insulating element 500.

[0047] In one possible implementation, the insulating component 500 comprises ceramic particles, which include at least one of alumina, boehmite, barium titanate, barium sulfate, titanium dioxide, melamine cyanurate, triphenyl phosphate, melamine polyphosphate, or ammonium polyphosphate. This allows the ceramic particles to utilize their inherent excellent insulating properties; adding them to the insulating component 500 significantly improves its insulation performance, effectively preventing current conduction and enhancing the insulation protection of the adapter 400.

[0048] In another possible implementation, the insulating component 500 comprises a polymer material, including at least one of polypropylene, polyethylene terephthalate, polyimide, polyethylene, or polyvinylidene fluoride. This polymer material typically possesses a certain degree of flexibility, facilitating the processing into insulating components 500 of various shapes and sizes to meet the insulation requirements of adapters 400 with different shapes and structures, thus enhancing the versatility of the insulating component 500. Furthermore, the covalent electrons within the polymer molecules are localized and cannot move freely, while the molecular chains are connected by weak van der Waals forces or hydrogen bonds, lacking freely moving electrons or ions. This gives the polymer material itself excellent insulating properties. When the adapter 400 is impacted or compressed and moves towards the metal casing 100, the insulating component 500 can act as a barrier, blocking the flow of current between the adapter 400 and the metal casing 100, thereby preventing a short circuit in the battery.

[0049] In one possible implementation, the insulating member 500 completely covers the bent portion 430 of the adapter 400. In a further example, the two side edges of the insulating member 500 in the width direction extend beyond the two side edges of the adapter 400, thus preventing deformation of the metal housing 100 and short circuits at the side contacts of the adapter 400 during drop tests. It should be understood that the width direction of the insulating member 500 is... Figures 1 to 3 The Y direction is shown. In another specific example, the insulating member 500 is arranged circumferentially around the adapter 400. While effectively preventing the adapter 400 from contacting the metal housing 100, the insulating member and the metal housing also prevent the adapter 400 from moving towards the cell 200, which could easily lead to a short circuit due to contact between the adapter 400 and the negative electrode in the cell 200.

[0050] In one possible implementation, please refer to Figure 4 The connecting section 213 of the positive electrode tab 210 and the first part 410 of the adapter 400 are welded together to form a first weld mark. In a specific example, the first weld mark can be formed by laser welding on the side of the adapter 400 away from the connecting section 213. That is, the first weld mark is formed by inward indentation from the side of the adapter 400 away from the connecting section 213, and at the same time, a weld mark protrusion is also formed on the side of the adapter 400 away from the connecting section 213.

[0051] The battery cell 200 includes a protective layer (not shown) on the surface of the first portion 410 facing away from the connecting section 213. The protective layer covers the first solder mark, that is, the protective layer is located between the first portion and the electrode body of the battery cell to prevent the first solder mark or solder mark protrusion on the first portion from contacting the negative electrode of the battery cell 200, thereby causing a short circuit. It should be noted that in the extending direction of the metal casing 100, the protective layer is located on the side of the first portion 410 facing away from the connecting section 213.

[0052] In a specific example, the protective layer may be, for example, adhesive tape or ceramic adhesive layer. The adhesive tape may extend from the first part 410 to the connection section 213, bending section 212 and lamination section 211 of the positive electrode tab 210, thereby further preventing the first solder mark from contacting the electrode body of the cell 200. It can also absorb the force of cell expansion on the positive electrode tab 210 and the adapter 400 during drop testing or charging and discharging. By simultaneously bonding the adapter 400 and the positive electrode tab 210, the protective layer can alleviate the pulling force of the cell 200 on the adapter 400 when the cell expands during drop testing or charging and discharging, and avoid affecting the welding strength between the positive electrode tab 210 and the adapter 400.

[0053] The insulating member 500 includes a first extension (not shown in the figure) extending onto the first portion 410. Part of the first extension is covered with a protective layer. It is understood that the insulating member 500 completely covers the bent portion 430 and partially extends into the first portion 410 and is covered by the protective layer. That is, the bent portion 430 and the first portion 410 of the adapter 400 are completely covered by the insulating member 500 and the protective layer, thereby achieving complete insulation between the bent portion 430 and the first portion 410 of the adapter 400 and the electrode body of the cell 200. This prevents the adapter 400, which is equipped with the insulating member 500, from colliding with the metal shell and bending towards the cell, which could easily lead to a short circuit between the adapter and the negative electrode in the cell.

[0054] In a specific example, the active layer of the positive electrode includes a thinned portion and a main body portion disposed along the extension direction of the tab, with the thinned portion located near the positive electrode tab of the positive current collector; similarly, the active layer of the negative electrode includes a thinned portion and a main body portion disposed along the extension direction of the negative electrode tab, with the thinned portion located near the negative electrode tab of the negative current collector. That is, the portion of the cell 200 near the adapter 400 is the thinned portion, and the total thickness of the corresponding thinned portion of the cell 200 is less than the total thickness of the main body portion. In the implementation where the insulating component 500 has a partially covered protective layer, when the adapter 400 with the insulating component 500 collides with the metal shell and bends towards the cell 200, under the premise of ensuring complete insulation between the negative electrode of the cell and the adapter, a certain receiving space can be formed at the position of the corresponding thinned part of the cell 200 to accommodate the bent adapter 400 and the insulating component 500, so as to prevent the adapter bending towards the cell from being too high, which could easily bump into the cover plate 115 and cause the adapter 400 to break.

[0055] In one possible implementation, please refer to Figure 4 The length of the overlapping portion between the first extension and the protective layer is less than or equal to 0.1 mm. While ensuring complete insulation between the negative electrode of the battery cell 200 and the inner surface of the adapter 400, the overlapping portion must be sufficiently small. Considering the relatively large thickness of the overlapping portion between the first extension and the protective layer, if the length of this overlapping portion exceeds 0.1 mm, the thicker portion will be too long. During the cyclic expansion of the battery cell, the adapter 400 may easily compress the electrode body of the battery cell 200, leading to powder shedding. It should be noted that the length of the overlapping portion between the first extension and the protective layer refers to the dimension in the thickness direction (such as the Z direction) of the metal casing 100.

[0056] In one possible implementation, the thickness of the insulating element 500 is greater than the thickness of the protective layer. In a further example, the thickness of the insulating element 500 is less than 1.6 times the thickness of the protective layer. Exemplarily, the thickness of the insulating element 500 is less than 1.6 times, 1.5 times, 1.4 times, 1.3 times, 1.2 times, 1.1 times, or any value within the area enclosed by any two of the above values. While ensuring the insulation protection function of the insulating element 500 and the protective layer, it is not necessary to excessively increase the thickness of the overlapping portion of the insulating element 500 and the protective layer. Thus, during the cyclic expansion of the battery cell, the adapter 400 is prevented from squeezing the electrode body of the battery cell 200, thereby avoiding the phenomenon of powder shedding.

[0057] In one possible implementation, please refer to Figure 4 The second part 420 of the adapter 400 and the pole assembly 300 are welded together to form a second solder mark; in such a case Figure 4In the specific example shown, the pole body 330 includes a straight portion and an insertion portion extending outward from the straight portion. The insertion portion passes through the through hole 113 and connects to the connecting piece 340. The second portion 420 of the adapter 400 is welded to the connecting piece 340, for example, by laser welding from the side of the second portion 420 facing away from the pole assembly 300. The insulating member 500 also includes a second extension extending to the second portion 420, with a gap between the second extension and the second weld mark. This ensures that the second extension does not partially cover the second weld mark area, preventing the insulating member 500 from affecting the welding of the second portion 420 of the adapter 400 and the pole assembly 300. Furthermore, during the welding process of the second portion 420 of the adapter 400 and the pole assembly 300, excessive welding energy is avoided, preventing the insulating member 500 from melting and incorporating into the second weld mark, thus preventing any impact on the welding strength of the second portion 420 and the pole assembly 300. In one specific example, the length of the second extension is less than or equal to half the length of the second portion 420.

[0058] In one possible implementation, the hardness of the insulating component 500 is greater than that of the metal casing 100. In a specific example, the Mohs hardness of the metal casing 100 is typically between 4 and 5. By adjusting the hardness of the insulating component 500 to be greater than that of the metal casing 100, the insulating component 500 can be prevented from detaching after repeated impacts and friction between the adapter 400 (with the insulating component 500) and the metal casing during drop tests or the expansion of the silicon-doped negative electrode cell. This prevents the adapter 400 from being exposed and avoids the possibility of short circuits between the adapter 400 and the metal casing 100. In a specific example, the insulating component 500 comprises ceramic particles with a Mohs hardness greater than 5, thus making the hardness of the insulating component 500 greater than that of the metal casing 100. During drop tests or the expansion of the silicon-doped negative electrode cell, the insulating component 500 on the adapter 400 will experience multiple impacts and friction with the metal casing. At this point, the higher hardness of the insulating component 500 allows it to better resist friction and impact, effectively reducing the risk of the insulating component 500 detaching. This prevents the adapter 400 from being exposed due to the insulating component 500 detaching, ultimately preventing a short circuit caused by contact between the adapter 400 and the metal housing 100, thus improving the product's safety and reliability.

[0059] In one possible implementation, the thickness of the insulating component 500 is less than or equal to twice the thickness of the adapter 400. In one specific example, the thickness of the insulating component 500 is 50μm-200μm. In another specific example, the thickness of the adapter 400 is 25μm-100μm. By ensuring that the thickness of the insulating component 500 is less than or equal to twice the thickness of the adapter 400, the insulation protection function of the insulating component 500 is maintained without excessively increasing the thickness of the overlapping portion of the insulating component 500 and the adapter 400. This prevents the adapter 400 from squeezing the electrode body of the cell 200 during the cell's cyclic expansion, thus avoiding powder shedding.

[0060] In one possible implementation, the length of the insulating member 500 is greater than or equal to the length of the bent portion 430, so that the insulating member 500 completely covers the bent portion 430 of the adapter 400. This effectively prevents the adapter 400 from contacting the metal housing 100 or the side wall, and also prevents the adapter from moving towards the direction of the battery cell due to the obstruction of the insulating member and the metal housing, which could easily lead to a short circuit between the adapter and the negative electrode in the battery cell.

[0061] In one possible implementation, the adhesive force between the insulating component 500 and the adapter 400 is ≥0.3 N / mm. It is understood that the insulating component 500 is located at the bent portion 430 of the adapter 400. During drop tests or cyclic expansion during the charging and discharging of a silicon-doped negative electrode cell, the bent portion 430 of the adapter 400 will be subjected to repeated bending. This embodiment, by controlling the adhesive force between the insulating component 500 and the adapter 400, can prevent the insulating component 500 from detaching during multiple bending processes, reducing the risk of contact between the adapter 400 and the metal casing 100. In another possible implementation, the length of the insulating component is greater than or equal to the length of the bent portion to achieve complete coverage of the bent portion by the insulating component.

[0062] In one possible implementation, the lead-out wall 112 includes an outwardly protruding flange 116, the vertex of the insulating member 500 covering the bent portion 430 of the adapter 400 not exceeding the flange 116, to prevent the vertex of the insulating member 500 covering the bent portion 430 from being too high, thus avoiding affecting the alignment connection of the cover plate 115 and the bottom shell 114, and also preventing excessive bending of the bent portion 430 and the insulating member 500.

[0063] The present invention will be described in detail below through embodiments. The embodiments described herein are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0064] The following examples illustrate the performance of the battery of the present invention after it has undergone drop testing.

[0065] Example 1

[0066] (I) Battery Preparation

[0067] Batteries are prepared according to the following method.

[0068] (1) Cell fabrication

[0069] A positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte are prepared. The negative electrode sheet of the battery cell contains 5% silicon by mass in its negative active layer. The positive electrode sheet includes a positive current collector and a positive electrode tab extending outward from one edge of the current collector; the positive electrode tab has a stacked section, a bent section, and a connecting section along its extension direction. The negative electrode sheet includes a negative current collector, a negative active layer on the current collector, and a negative electrode tab extending outward from one edge of the current collector, with the negative active layer containing 5% silicon by mass.

[0070] The above-mentioned positive electrode sheet, negative electrode sheet and separator are stacked to form a core; or the above-mentioned positive electrode sheet, negative electrode sheet and separator are stacked and wound to form a wound core.

[0071] (2) Preparation of adapter

[0072] The adapter includes a first part, a second part, and a bent portion connecting the first part and the second part, the bent portion being bent in a direction away from the connecting section.

[0073] An insulating element is at least partially covered on the bent portion of the adapter, and the insulating element is arranged around the axis of the adapter, and the insulating element includes a first extension extending onto the first portion.

[0074] The insulating component includes ceramic particles, which include at least one of alumina, boehmite, barium titanate, barium sulfate, titanium dioxide, melamine cyanurate, triphenyl phosphate, melamine polyphosphate, or ammonium polyphosphate.

[0075] The insulating component includes a polymer material, which includes at least one of polypropylene, polyethylene terephthalate, polyimide, polyethylene, or polyvinylidene fluoride.

[0076] Among them, the hardness of the insulating component is greater than that of the metal shell, the Mohs hardness of the ceramic shell is 5.5, the ratio of the thickness of the insulating component to the thickness of the adapter is 1, the thickness of the insulating component is 50μm, and the adhesion between the insulating component and the adapter is 0.3N / mm.

[0077] (3) Preparation of pole assembly

[0078] (4) Preparation of metal casing

[0079] The metal casing has a receiving cavity and an extension wall with a through hole communicating with the receiving cavity. The metal casing includes a bottom shell and a cover plate, with the through hole located on the cover plate.

[0080] (5) Battery fabrication

[0081] The battery cell prepared in step (1) and the adapter prepared in step (2) are connected together to form a first assembly. Optionally, the connecting section of the positive electrode tab and the first part of the adapter are welded together to form a first solder mark.

[0082] Subsequently, a protective layer is prepared on the surface of the first portion facing away from the connecting section, the protective layer covering the first solder mark; and the first extension portion is covered with a protective layer.

[0083] The length of the overlap between the first extension and the protective layer is 0.1 mm. And / or, the thickness of the insulating element is greater than the thickness of the protective layer.

[0084] The electrode assembly prepared in step (3) is installed onto the cover plate, and part of the electrode assembly is inserted through the through hole into the inside of the cover plate to form a second assembly.

[0085] The pole assembly in the second assembly is welded to the second part of the adapter to form a second weld mark.

[0086] The first and second assemblies, which are connected together as described above, are installed into the bottom shell, and the bottom shell and the cover plate are welded and sealed to form a battery.

[0087] (II) Battery drop test

[0088] The battery prepared in step (1) is released in a free state and dropped vertically from a platform at a certain height to conduct a drop test.

[0089] Repeat the drop test at least once after a preset time interval.

[0090] After completing at least one of the above-mentioned drop tests, the voltage drop of the battery is tested. At this time, the voltage drop is 0.4V. Compared with related technologies, if the adapter and the metal casing short-circuit, the voltage drop of the battery is greater than or equal to 0.5V. This can indirectly verify that the adapter of the battery prepared in the embodiment of this application does not short-circuit with the metal casing.

[0091] Example 2

[0092] The difference from Example 1 is that the elemental silicon content in the negative electrode active layer of the negative electrode sheet is 20% by mass. The length of the overlap between the first extension and the protective layer is 0.08 mm. The Mohs hardness of the ceramic shell is 6; the ratio of the thickness of the insulating component to that of the adapter is 1.2 times; the thickness of the insulating component is 80 μm; and the adhesion between the insulating component and the adapter is 0.35 N / mm.

[0093] Example 3

[0094] The difference from Example 1 is that the elemental silicon content in the negative electrode active layer of the negative electrode sheet is 30% by mass. The length of the overlap between the first extension and the protective layer is 0.06 mm. The Mohs hardness of the ceramic shell is 6.5; the ratio of the thickness of the insulating component to that of the adapter is 1.4 times; the thickness of the insulating component is 100 μm; the adhesion force between the insulating component and the adapter is 0.5 N / mm; and the voltage drop of the tested battery is 0.3 V.

[0095] Example 4

[0096] The difference from Example 1 is that the elemental silicon content in the negative electrode active layer of the negative electrode sheet is 40% by mass. The length of the overlap between the first extension and the protective layer is 0.05 mm. The Mohs hardness of the ceramic shell is 7; the ratio of the thickness of the insulating component to that of the adapter is 1.6 times; the thickness of the insulating component is 120 μm; the adhesion force between the insulating component and the adapter is 0.6 N / mm; and the voltage drop of the test battery is 0.2 V.

[0097] Example 5

[0098] The difference from Example 1 is that the elemental silicon content in the negative electrode active layer of the negative electrode sheet is 50% by mass. The length of the overlap between the first extension and the protective layer is 0.04 mm. The Mohs hardness of the ceramic shell is 7.5; the ratio of the thickness of the insulating component to that of the adapter is 1.8 times; the thickness of the insulating component is 160 μm; the adhesion force between the insulating component and the adapter is 0.6 N / mm; and the voltage drop of the tested battery is 0.1 V.

[0099] Example 6

[0100] The difference from Example 1 is that the elemental silicon content in the negative electrode active layer of the negative electrode sheet is 60% by mass. The length of the overlap between the first extension and the protective layer is 0.02 mm. The Mohs hardness of the ceramic shell is 8; the ratio of the thickness of the insulating component to that of the adapter is 2; the thickness of the insulating component is 200 μm; the adhesion force between the insulating component and the adapter is 0.8 N / mm; and the voltage drop of the tested battery is 0.05 V.

[0101] Comparative Example

[0102] Unlike Example 1, no insulating component is provided on the adapter during the battery manufacturing process.

[0103] Table 1. Battery parameters for the examples and comparative examples.

[0104]

[0105] As can be clearly seen from Table 1, in Examples 1 to 6, by providing an insulating component between the adapter and the metal casing, the battery voltage drop met the requirements after at least two drop tests, with each voltage drop being less than 0.5V. This proves that no short circuit occurred between the adapter and the metal casing. In the comparative example, however, no insulating component was provided between the adapter and the metal casing. After at least two drop tests, the battery voltage drop was found to be greater than 0.5V, proving that a short circuit occurred between the adapter and the metal casing.

[0106] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

[0107] Although embodiments of the 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 invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery, characterized by, The application relates to a battery cell, comprising: a metal shell having a containing cavity, the metal shell having a lead-out wall surface provided with a through hole in communication with the containing cavity; an electric core arranged in the containing cavity, the electric core comprising a positive electrode sheet, a negative electrode sheet and a diaphragm arranged in layers, the positive electrode sheet comprising a positive electrode current collector and a positive electrode tab formed by extending outward from one side edge of the positive electrode current collector, the positive electrode tab being formed with a stacking section, a bending section and a connecting section along the extending direction of the positive electrode tab; the negative electrode sheet comprising a negative electrode current collector, a negative electrode active layer on the negative electrode current collector and a negative electrode tab formed by extending outward from one side edge of the negative electrode current collector, the negative electrode tab being connected with the lead-out wall surface of the metal shell, and the mass content of elemental silicon in the negative electrode active layer being 5%-60%; a pole assembly arranged in the through hole; an adapter comprising a first part connected with the connecting section of the positive electrode tab, a second part connected with the pole assembly and a bending part connecting the first part and the second part, the bending part being bent towards a direction away from the connecting section, and along the length direction of the metal shell, the connecting section of the positive electrode tab being located between the first part and the second part; at least part of the bending part of the adapter is covered by an insulating member, and the insulating member is located on one side surface of the bending part away from the connecting section.

2. The battery of claim 1, wherein, The insulating member is arranged in a circumferential direction of the adapter.

3. The battery of claim 1, wherein, The connecting section of the positive electrode tab and the first part of the adapter are welded to form a first welding mark; the electric core comprises a protective layer located on one side surface of the first part away from the connecting section, and the protective layer covers the first welding mark; the insulating member comprises a first extension part extending to the first part, and the first extension part is partially covered by the protective layer.

4. The battery of claim 3, wherein, The length of the overlapping part of the first extension part and the protective layer is less than or equal to 0.1 mm, and / or the thickness of the insulating member is greater than the thickness of the protective layer.

5. The battery of claim 1, wherein, The second part of the adapter and the pole assembly are welded to form a second welding mark; the insulating member comprises a second extension part extending to the second part, and a spacing distance is left between the second extension part and the second welding mark.

6. The battery of claim 1, wherein, The insulating member comprises ceramic particles, and the ceramic particles comprise at least one of alumina, boehmite, barium titanate, barium sulfate, titanium dioxide, melamine cyanurate, triphenyl phosphate, melamine polyphosphate or ammonium polyphosphate, or the insulating member comprises a high polymer material, and the high polymer material comprises at least one of polypropylene, polyethylene terephthalate, polyimide, polyethylene or polyvinylidene fluoride.

7. The battery of claim 1, wherein, The hardness of the insulating member is greater than the hardness of the metal shell, and / or the ceramic particles have a Mohs hardness greater than 5.

8. The battery of claim 1, wherein, The thickness of the insulating member is less than or equal to 2 times the thickness of the adapter.

9. The battery of claim 1, wherein, The thickness of the insulation part is 50-200 microns, and / or the length of the insulation part is greater than or equal to the length of the bending part, and / or the bonding force between the insulation part and the adapter part is greater than or equal to 0.3 N / mm.

10. The battery of claim 1, wherein, The leading wall surface comprises a flange formed by protruding outward, and the vertex of the insulation part of the bending part of the adapter part does not exceed the flange.

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