Secondary batteries, battery packs, and electronic devices

Abstract

The present invention provides a secondary battery, a battery pack, and an electronic device that can at least avoid damaging the separator during the manufacturing process. [Solution] Embodiments of the present invention provide a secondary battery, a battery pack, and an electronic device, the secondary battery including an electrode assembly, the electrode assembly including a negative electrode sheet, a positive electrode sheet, and a separator placed between the negative electrode sheet and the positive electrode sheet, the uncoated negative electrode area of ​​the negative electrode sheet including a negative electrode tab and a negative electrode connection area connected between the negative electrode tab and the negative electrode coated area, the negative electrode tab including a negative electrode tab body and a negative electrode tab transition portion connected between the negative electrode connection area and the negative electrode tab body, the negative electrode tab transition portion including a first negative electrode tab transition endpoint, the first negative electrode tab transition endpoint being the position where the tangent to the negative electrode tab transition portion intersects with the extending direction of the negative electrode connection area, and the distance range between the first negative electrode tab transition endpoint and the first separator end in the first direction of the separator is 0.5 to 2 mm.

Description

Technical Field

[0001] The present invention relates to secondary batteries, battery packs, and electronic devices.

Background Art

[0002] In the field of new energy power batteries, the application of secondary batteries has become increasingly widespread. For example, secondary batteries (such as lithium-ion batteries) can be applied to electronic devices such as vehicles, power storage, mobile phones, tablet computers, wearable devices, mobile power supplies, electronic cigarettes, digital products, power tools, power devices, and power storage devices. One type of secondary battery is a cylindrical battery, which includes a shell and an electrode assembly. The electrode assembly includes a positive electrode sheet, a first separator, a negative electrode sheet, and a second separator. After being sequentially laminated with each other, they are wound to form an electrode assembly, and then enclosed in the shell. However, existing secondary batteries still need further improvement in some aspects.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In view of the problems existing in the related art, an object of the present invention is to provide a secondary battery, a battery pack, and an electronic device, which can avoid damaging the separator at least during the manufacturing process.

Means for Solving the Problems

[0004] To achieve the above objectives, an embodiment of the present invention provides a secondary battery, the secondary battery comprising an electrode assembly including a negative electrode sheet, a positive electrode sheet, and a separator placed between the negative electrode sheet and the positive electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer, the negative electrode current collector comprising a negative electrode coated region covered by the negative electrode active material layer and a negative electrode uncoated region not covered by the negative electrode active material layer, the direction from the negative electrode coated region to the negative electrode uncoated region is defined as the first direction, and the separator comprises a first separator end in the first direction, the first direction Along this line, the uncoated negative electrode region includes a negative electrode tab and a negative electrode connection region connected between the negative electrode tab and the negative electrode coated region; the negative electrode tab includes a negative electrode tab body and a negative electrode tab transition portion connected between the negative electrode connection region and the negative electrode tab body; the negative electrode tab transition portion includes a first negative electrode tab transition endpoint connected to the negative electrode connection region; the first negative electrode tab transition endpoint is the position where the tangent to the negative electrode tab transition portion intersects with the direction in which the negative electrode connection region extends; and the distance over which the first negative electrode tab transition endpoint extends beyond the first separator end in the first direction is 0.5 to 2 mm.

[0005] In some embodiments, the negative electrode active material layer includes a first negative pole in a first direction, and the distance over which the first negative electrode tab transition endpoint extends beyond the first negative pole in the first direction is 1.5 to 3 mm.

[0006] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer includes a first positive electrode end in a first direction, and the distance by which the first negative electrode end extends beyond the first positive electrode end in the first direction is 1.0 to 1.5 mm.

[0007] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode current collector includes a positive electrode coated region covered by the positive electrode active material layer and a positive electrode uncoated region not covered by the positive electrode active material layer, the direction from the positive electrode coated region to the positive electrode uncoated region is defined as the second direction, the second direction being opposite to the first direction, and along the second direction, the positive electrode uncoated region includes a positive electrode tab and a positive electrode connection portion connected between the positive electrode tab and the positive electrode coated region. The positive electrode tab includes a positive electrode tab body and a positive electrode tab transition portion connected between the positive electrode connector and the positive electrode tab body, the positive electrode tab transition portion includes a first positive electrode tab transition endpoint connected to the positive electrode connector, the first positive electrode tab transition endpoint is located where the tangent to the positive electrode tab transition portion intersects with the extending direction of the positive electrode connector, the electrode assembly further comprises an insulating layer, the insulating layer covers the positive electrode connector, and the width of the insulating layer in the second direction is 0.5 to 2.5 mm.

[0008] In some embodiments, the negative electrode active material layer includes a second negative electrode end in a second direction, the insulating layer includes a first insulating layer end in a first direction, and the distance over which the second negative electrode end extends beyond the first insulating layer end in the second direction is 0.5 to 1 mm.

[0009] In some embodiments, the insulating layer includes a second insulating layer edge in a second direction, and the distance over which the second insulating layer edge extends to the second negative pole in the second direction is 0.5 to 1 mm.

[0010] In some embodiments, the negative electrode active material layer includes a first negative pole in a first direction, where the distance over which the first separator end extends beyond the first negative pole in the first direction is 0.5 to 1.5 mm.

[0011] In some embodiments, the secondary battery further comprises a case used to house an electrode assembly, the case including a circumferential side wall and an end wall connected to one end of the circumferential side wall, the other end of the circumferential side wall having an opening, the circumferential side wall adjacent to the opening having a pressure contact portion projecting inward, the electrode assembly being located between the end wall and the pressure contact portion, the negative electrode tab facing the opening and connected to the case via a negative electrode current collector plate, the welding position between the negative electrode current collector plate and the circumferential side wall being located on the side of the pressure contact portion facing the electrode assembly. [Effects of the Invention]

[0012] The beneficial technical effects of this invention are as follows: The present invention's technical proposal sets the distance over which the first negative electrode tab transition endpoint of the negative electrode sheet extends beyond the first negative electrode end to 0.5 to 2 mm, thereby preventing damage to the separator during the manufacturing process, avoiding excessive space waste, and ensuring that the negative electrode current collector does not undergo undesirable deformation. For example, since the negative electrode tab body of the negative electrode current collector is welded to the negative electrode current collector plate, there is a high risk of burning out the separator during the welding process. However, the present invention's technical proposal can avoid burning out the separator during the welding process, avoid excessive space waste, and ensure that the negative electrode current collector does not undergo undesirable deformation. [Brief explanation of the drawing]

[0013] To more clearly illustrate embodiments of the present invention or technical concepts in the prior art, the accompanying drawings that may be used in the description of embodiments or the prior art are briefly introduced below. Clearly, the accompanying drawings in the following description are some embodiments of the present invention, and those skilled in the art can obtain other accompanying drawings based on these without expending any creative effort.

[0014] [Figure 1] This is an explanatory diagram showing an example of the present invention where the electronic device is in a vehicle. [Figure 2] This is a perspective view of a secondary battery based on an embodiment of the present invention. [Figure 3]A cross-sectional view of a secondary battery based on an embodiment of the present invention. [Figure 4] A cross-sectional view of an electrode assembly based on some embodiments. [Figure 5A] A cross-sectional explanatory view of the negative electrode sheet in region A1 of FIG. 4. [Figure 5B] A cross-sectional explanatory view of the positive electrode sheet in region A2 of FIG. 4. [Figure 6A] A cross-sectional explanatory view showing related dimensions of the negative electrode sheet in the electrode assembly of some embodiments. [Figure 6B] A cross-sectional explanatory view showing related dimensions of the negative electrode sheet in the electrode assembly based on some embodiments. [Figure 6C] An explanatory view showing the relationship between the positive electrode sheet and the negative electrode sheet in the electrode assembly based on some embodiments.

MODE FOR CARRYING OUT THE INVENTION

[0015] In order to better understand the spirit of the embodiments of the present invention, some preferred embodiments of the present invention will be further described in combination below.

[0016] Embodiments of the present invention will be described in detail below. Throughout the entire text of the specification of the present invention, components having the same or similar configurations and components having the same or similar functions are represented by similar reference numerals. The embodiments related to the drawings described herein are of an illustrative nature and are used to provide a basic understanding of the present invention. The embodiments of the present invention should not be construed as a limitation of the present invention.

[0017] The terms "substantially", "essentially", "substantially" and "about" used in the present text are used to describe and explain small changes. When used in combination with an event or situation, the terms can refer to an example in which the event or situation occurs exactly and an example in which the event or situation occurs very approximately therein.

[0018] In this specification, unless otherwise specified or limited, terms of relativity, such as “center,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “internal,” “external,” “lower,” “higher,” “horizontal,” “vertical,” “higher,” “lower,” “upper,” “downward,” “top,” “bottom,” and their derived terms (e.g., “horizontally,” “downward,” “upward,” etc.), should be interpreted as referring to the direction described in the discussion or in the drawings. These terms of relativity are used solely for descriptive convenience and do not require the invention to be constructed or operated in any particular direction.

[0019] For convenience of description, terms such as "First," "Second," "Third," etc., may be used in the text to distinguish different components of a single figure or a series of figures. These terms are not intended to describe corresponding components. Furthermore, where not contradictory, the embodiments and features described herein can be combined with each other. The present invention will be described in detail below in combination with the embodiments, with reference to the drawings.

[0020] The present invention provides an electronic device 1000. For the convenience of description in the following embodiments, the case where the electronic device 1000 is a vehicle will be taken as an example for explanation. Referring to FIG. 1, a battery pack 1002 is installed inside the vehicle, and the battery pack 1002 can be installed at the bottom or the head or the tail of the vehicle body 1001. The battery pack 1002 can be used for power supply of the vehicle. For example, the battery pack 1002 can be used as the operating power source of the vehicle. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain power assistance. The vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or a range extender vehicle, etc., but is not limited thereto. The working part is the vehicle body, and the battery pack 1002 is installed at the bottom of the vehicle body to provide power assistance for the running of the vehicle or the operation of the in-vehicle electrical components. However, in some other embodiments, the electronic device 1000 may further be a mobile phone, a portable device, a notebook computer, a ship, an aircraft, an electric toy and an electric tool, etc. The aircraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc. The working part may be a unit component that obtains the power of the battery pack 1002 and performs corresponding work. For example, it may be a fan blade rotation unit, a dust suction working unit of a vacuum cleaner, etc. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy and an electric aircraft toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, such as an electric drill, an electric grinding machine, an electric wrench, an electric driver, an electric hammer, an impact electric drill, a concrete vibrator and an electric saw, etc. The embodiments of the present invention do not impose special restrictions on the above-mentioned electronic device 1000.

[0021] The battery pack 1002 can include a plurality of secondary batteries (secondary battery 100 in FIG. 2) and a case for accommodating the plurality of secondary batteries. In the following description, the case where the secondary battery is a cylindrical battery will be taken as an example for explanation. FIG. 2 shows a perspective view of the secondary battery 100 according to an embodiment of the present invention, and FIG. 3 shows a cross-sectional view of the secondary battery 100 according to an embodiment of the present invention.

[0022] Referring together to Figures 2 and 3, the secondary battery 100 is a cylindrical battery. The secondary battery 100 may include an electrode assembly 120, an electrolyte, a case 200, and a cover plate 220. The case 200 includes a circumferential side wall 109 and an end wall 111 connected to one end of the circumferential side wall 109, with an opening 205 provided at the other end of the circumferential side wall 109 opposite the end wall 111, and the cover plate 220 covers the opening 205. The cover plate 220 can be used together with the case 200 to enclose the electrode assembly 120 and the electrolyte. The material of the case 200 may be any of the many usable materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. The case 200 may be cylindrical, defining a housing chamber, and the electrode assembly 120 is installed within the housing chamber. The outer diameter of case 200 can be determined based on the specific diameter of electrode assembly 120, for example, the outer diameter of case 200 may be 18 mm, 21 mm, 46 mm, etc. In some embodiments, the secondary battery 100 may be a 4680 cylindrical battery (outer diameter 46 mm, height 80 mm), or a 4695 cylindrical battery (outer diameter 46 mm, height 95 mm), or a 46120 cylindrical battery (outer diameter 46 mm, height 120 mm). The secondary battery is a cylindrical battery.

[0023] The electrode assembly 120 can be formed by sequentially stacking and winding a positive electrode sheet, a negative electrode sheet, and a separator located between the positive and negative electrode sheets (described in detail below). The wound electrode assembly 120 may have a winding center hole 120c. In some embodiments, the positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer being coated on a portion of the positive electrode current collector. The uncoated positive electrode area 28b of the positive electrode current collector, not covered by the positive electrode coated area, can be used to form a positive electrode tab. The negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer being coated on a portion of the negative electrode current collector. The uncoated negative electrode area 18b of the negative electrode current collector, not covered by the negative electrode coated area, can be used to form a negative electrode tab.

[0024] A pressure contact portion 113 (which can also be called a rolling groove) that protrudes inward is formed on the circumferential side wall of the case 200 adjacent to the opening 205. The electrode assembly 120 is installed between the end wall 111 and the pressure contact portion 113, and the pressure contact portion 113 can restrict the movement of the electrode assembly 120 in the height direction and the opposite direction between the end wall 111 and the pressure contact portion 113. The end of the circumferential side wall 109 of the case 200 on the opening 205 side can be configured as a rolled edge portion 32, which extends inward in the radial direction of the case 200. The rolled edge portion 32 and the pressure contact portion 113 are spaced apart in the height direction, and the pressure contact portion 113 and the rolled edge portion 32 can jointly clamp the cover plate 220. The cover plate 220 is electrically insulated from the case 200.

[0025] The uncoated negative electrode region 18b of the electrode assembly 120 faces the opening 205 and can be electrically connected to the case 200 via the negative electrode current collector plate 201 located between the cover plate 220 and the electrode assembly 120, thereby causing the case 200 to be negatively charged. The negative electrode current collector plate 201 can be welded to the case 200 by laser welding. Specifically, the welding position between the negative electrode current collector plate 201 and the circumferential side wall 109 of the case 200 is located on the side of the pressure-welded portion 113 facing the electrode assembly 120.

[0026] The secondary battery 100 may further include a pole 160 which penetrates the end wall 111 and is insulated from the end wall 111. The pole 160 can be electrically connected to the uncoated positive region 28b of the positive electrode sheet via a positive electrode current collector plate 202 located between the pole 160 and the electrode assembly 120, thereby giving the pole 160 a positive potential. In some embodiments, the pole 160 can be welded to the positive electrode current collector plate 202 by laser penetration welding.

[0027] In an example of the cylindrical battery of the present invention, the method for manufacturing the secondary battery 100 of the present invention includes the following steps.

[0028] Winding: In a winding structure formed by stacking and winding a negative electrode sheet, a separator, and a positive electrode sheet, the uncoated negative electrode region 18b of the negative electrode sheet and the uncoated positive electrode region 28b of the positive electrode sheet are used as the positive electrode tab and the negative electrode tab, and the uncoated positive electrode region 28b and the uncoated negative electrode region 18b are bent along the radial direction of the electrode assembly 120.

[0029] Welding of current collector plates and electrode assemblies: The positive electrode current collector plate 202 and the negative electrode current collector plate 201 are welded to the surface areas of the bent uncoated positive electrode region 28b and the uncoated negative electrode region 18b, respectively.

[0030] Case insertion: The electrode assembly 120, with the negative electrode current collector plate 201 and the positive electrode current collector plate 202 welded together, is installed into the case 200 through the opening 205. The method of installing the electrode assembly 120 in this step is not limited and may be done manually or by mechanical hand.

[0031] Install the pole 160.

[0032] Electrolyte injection: The method of electrolyte injection is not limited, and injection can be performed through the opening 205. In this embodiment, the electrolyte is injected through the opening 205, reducing the step of creating an injection hole in the end wall 111, and allowing injection to be performed by directly utilizing the existing opening 205, thereby simplifying the process and reducing costs.

[0033] Sealing: The cover plate 220 is sealed and mounted on the opening 205. There are various sealing methods, and this is not limited to them. In some embodiments, first, the outer circumference of the case 200 is rolled to form a recessed contact portion 113 toward the center of the case 200, thereby restricting the height movement of the electrode assembly 120. Then, a mechanical sealing process is employed to crimp the cover plate 220 to form a rolled edge portion 32, thereby sealing and mounting the cover plate 220 on the opening 205 of the case 200. This step is a mature process, low-cost, and highly efficient.

[0034] Figure 4 shows cross-sectional views of electrode assemblies 120 according to several embodiments. As shown in Figure 4, the electrode assembly 120 is mainly formed by winding a negative electrode sheet 10 and a positive electrode sheet 20, with a separator 122 placed between the negative electrode sheet 10 and the positive electrode sheet 20. The electrolyte can be filled between the negative electrode sheet 10, the positive electrode sheet 20 and the separator 122.

[0035] The negative electrode sheet 10 may include a negative electrode current collector 18 and a negative electrode active material layer 16, wherein a portion of the relative surface of the negative electrode current collector 18 along its thickness direction is covered by the negative electrode active material layer 16, so that the negative electrode current collector 18 includes a negative electrode coated region 18a covered by the negative electrode active material layer 16 and a negative electrode uncoated region 18b not covered by the negative electrode active material layer 16. The positive electrode sheet 20 includes a positive electrode current collector 28 and a positive electrode active material layer 26, wherein at least a portion of the relative surface of the positive electrode current collector 28 along its thickness direction is covered by the positive electrode active material layer 26, so that the positive electrode current collector 28 includes a positive electrode coated region 28a covered by the positive electrode active material layer 26 and a positive electrode uncoated region 28b not covered by the positive electrode active material layer 26. The direction from the negative electrode coated region 18a to the negative electrode uncoated region 18b is the first direction D1. The opposite direction of the first direction D1 is the second direction D2. The uncoated negative electrode region 18b of the negative electrode current collector 18 can be used to form a negative electrode tab. The uncoated positive electrode region 28b of the positive electrode current collector 28 can be used to form a positive electrode tab.

[0036] Taking a lithium-ion battery as an example, the material of the negative electrode current collector 18 may be, for example, copper, and the negative electrode current collector 18 is copper foil. The negative electrode active material of the negative electrode active material layer 16 may be carbon or silicon, etc. The material of the positive electrode current collector 28 may be, for example, aluminum, and the positive electrode active material of the positive electrode active material layer 26 may be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The material of the separator 122 may be PP (polypropylene) or PE (polyethylene), etc.

[0037] Figure 5A shows a cross-sectional diagram of the negative electrode sheet 10 in region A1 in Figure 4. As shown in Figure 5A, the uncoated negative electrode region 18b includes a negative electrode tab 18b2 and a negative electrode connection area 18b1 connected between the negative electrode tab 18b2 and the coated negative electrode region 18a. The negative electrode tab 18b2 includes a negative electrode tab body 18b22 and a negative electrode tab transition area 18b21 connected between the negative electrode connection area 18b1 and the negative electrode tab body 18b22. In the cross-sectional view of Figure 5A, the negative electrode tab transition area 18b21 has a curved extension path, and the negative electrode tab body 18b22 has a straight extension path. The extension path of the negative electrode connection area 18b1 is a straight line along the first direction D1.

[0038] The negative electrode tab transition section 18b21 includes a first negative electrode tab transition endpoint E11 connected to the negative electrode connection area 18b1, where the tangent to the negative electrode tab transition section 18b21 intersects with the extension direction of the negative electrode connection area 18b1. The negative electrode tab transition section 18b21 further includes a second negative electrode tab transition endpoint E12, where the tangent to the negative electrode tab transition section 18b21 intersects with the extension direction of the negative electrode tab body 18b22.

[0039] Figure 5B shows a cross-sectional diagram of the positive electrode sheet 20 in region A2 in Figure 4. As shown in Figure 5B, the uncoated positive electrode region 28b includes a positive electrode tab 28b2 and a positive electrode connection portion 28b1 connected between the positive electrode tab 28b2 and the coated positive electrode region 28a. The positive electrode tab 28b2 includes a positive electrode tab body 28b22 and a positive electrode tab transition portion 28b21 connected between the positive electrode connection portion 28b1 and the positive electrode tab body 28b22. In the cross-sectional view of Figure 5B, the positive electrode tab transition portion 28b21 has a curved extension path, and the positive electrode tab body 28b22 has a straight extension path. The extension path of the positive electrode connection portion 28b1 is a straight line along the second direction D2.

[0040] The positive electrode tab transition section 28b21 includes a first positive electrode tab transition endpoint E21 connected to the positive electrode connection section 28b1, where the tangent to the positive electrode tab transition section 28b21 intersects with the extension direction of the positive electrode connection section 28b1. The positive electrode tab transition section 28b21 further includes a second positive electrode tab transition endpoint E22, where the tangent to the positive electrode tab transition section 28b21 intersects with the extension direction of the positive electrode tab body 28b22. The insulating layer 40 covers the positive electrode connection section 28b1. By installing the insulating layer 40, the possibility of contact between the negative electrode sheet 10 and the positive electrode sheet 20 can be minimized. The insulating layer 40 can be installed on both sides of the uncoated positive electrode region 28b. The insulating layer 40 can effectively prevent electrical contact between the negative electrode sheet 10 and the positive electrode sheet 20.

[0041] In some embodiments, the main composition of the insulating layer 40 is boehmite and PVDF (polyvinylidene difluoride). The occupancy rate of boehmite is 80%, and the occupancy rate of PVDF is 20%. In some embodiments, the insulating layer is a ceramic material layer. The thickness of the insulating layer 40 may be 1.5 to 2.5 mm, for example, 1.5 mm, 1.7 mm, 2 mm, 2.1 mm, 2.3 mm, or 2.5 mm. By setting a thickness range for the insulating layer 40, it is possible to avoid the coating thickness of the insulating layer 40 being too thin, thus preventing difficulties in obtaining the required electrical insulation and support strength. At the same time, it is possible to avoid the thickness of the insulating layer 40 being too thick, thus preventing the curing time of the coating layer from becoming longer and the overall thickness of the structure from increasing.

[0042] In some embodiments, the insulating layer 40 contains a coloring agent, and the coloring action of the coloring agent distinguishes whether one side to which the insulating layer 40 is applied is the front or back side of the positive electrode sheet 20. This includes, but is not limited to, cases where the surface density of the front and back sides of the positive electrode sheet 20 is distinguished. The main component of the coloring agent can be bismuth vanadate, which exhibits a yellow color.

[0043] Figure 6A shows a cross-sectional diagram illustrating the dimensions related to the negative electrode sheet in an electrode assembly based on several embodiments. In Figure 6A, the separator 122 is shown to have an upper end in the first direction D1, referred to as the first separator end 122u, and the separator 122 has a lower end in the second direction D2, referred to as the second separator end 122l. The height of the separator 122 in cross-section is H 122 That is the case.

[0044] In some embodiments, the distance H3 in the first direction D1 between the first negative electrode tab transition endpoint E11 and the first separator end 122u of the separator 122 is in the range of 0.5 to 2 mm. The extreme positional relationship between the first negative electrode tab transition endpoint E11 and the first separator end 122u of the separator 122 is 0 (i.e., H3 is 0), but since the negative electrode tab body 18b22 is welded to the negative electrode current collector plate, there is a high risk of burning out the separator 122 during the welding process. If the distance H3 is excessively large, a large amount of space is wasted, and the negative electrode current collector may not be supported, potentially causing bending. The technical proposal of the present invention sets the distance H3 in the range of 0.5 to 2 mm, thereby avoiding burning out the separator 122 during the welding process, without excessive space waste, and ensuring that the negative electrode current collector does not undergo undesirable deformation.

[0045] Furthermore, the negative electrode active material layer 16 has an upper end in the first direction D1 and is referred to as the first negative pole end 16u, and the negative electrode active material layer 16 has a lower end in the second direction D2 and is referred to as the second negative pole end 16l. In some embodiments, the distance by which the first negative electrode tab transition endpoint E11 extends beyond the first negative pole end 16u in the first direction D1 is H6, and the range of distance H6 can be 1.5 to 3 mm. This range of value for distance H6 avoids the amount of heat during the welding period between the negative electrode tab body 18b22 and the negative electrode current collector plate affecting the negative electrode active material layer 16, and also avoids excessive waste of space.

[0046] Figure 6B shows a cross-sectional diagram illustrating the relevant dimensions of the negative electrode sheet 10 in an electrode assembly according to several embodiments. As shown in Figures 4 to 6B, in some embodiments, the insulating layer 40 has a width H8 in the second direction D2, and the width H8 can range from 0.5 to 2.5 mm. An insulating layer 40 within this range can provide good support and simultaneously provide good electrical insulation. If the width H8 is greater than 2.5 mm, it will excessively waste internal battery space. In preferred embodiments, the width H8 of the insulating layer 40 is 2 to 2.5 mm. In some embodiments, the insulating layer 40 may be adjacent to the first positive electrode tab transition endpoint E21, i.e., the positive electrode tab 28b2 begins to bend at the lower end of the insulating layer 40.

[0047] In some embodiments, the insulating layer 40 does not need to be placed on the uncoated positive electrode region 28b. In such embodiments, the distance between the first positive electrode tab transition endpoint E21 and the second separator end 122l of the separator 122 may be 0.5 to 2 mm (similar to the situation on the negative electrode side).

[0048] Figure 6C shows an explanatory diagram of the relationship between the positive electrode sheet and the negative electrode sheet in an electrode assembly according to several embodiments. As shown in Figure 6C, in some embodiments, the distance H4 is the distance over which the first separator end 122u (upper end) of the separator 122 extends beyond the first negative electrode end 16u (upper end) of the negative electrode active material layer 16 in the first direction D1. In some embodiments, the range of distance H4 is 0.5 to 1.5 mm. Preferably, the distance H4 is approximately 1 mm. By the upper end of the separator extending beyond the negative electrode active material layer, it is possible to prevent situations such as displacement of the negative electrode in a vibrating environment, thereby improving battery safety.

[0049] The positive electrode active material layer 26 has an upper end in the first direction D1 and is referred to as the first positive electrode end 26u, and the negative electrode active material layer 16 has a lower end in the second direction D2 and is referred to as the second positive electrode end 26l. In the first direction D1, the distance by which the first negative electrode end 16u (upper end) of the negative electrode active material layer 16 extends beyond the first positive electrode end 26u (upper end) of the positive electrode active material layer 26 of the positive electrode sheet 20 is H2. In some embodiments, the distance H2 is 1.0 to 1.5 mm, which prevents lithium deposition and does not excessively occupy the internal space of the battery.

[0050] The insulating layer 40 has an upper end in the first direction D1 and is referred to as the first insulating layer end 40u, and the insulating layer 40 has a lower end in the second direction D2 and is referred to as the second insulating layer end 40l. In some embodiments, in the second direction D2, the distance H7 by which the second insulating layer end 40l (lower end) of the insulating layer 40 extends beyond the second negative electrode end 16l (lower end) of the negative electrode active material layer 16 is 0.5 to 1 mm, ensuring electrical insulation without excessively occupying the internal space of the battery.

[0051] In some embodiments, in the second direction D2, the distance by which the second negative electrode end 16l (lower end) of the negative electrode active material layer 16 extends beyond the first insulating layer end 40u (upper end) of the insulating layer 40 is H1, and the range of distance H1 is 0.5 to 1 mm. This ensures that the insulating layer 40 isolates the lower end of the negative electrode active material layer 16 from the positive electrode sheet, guaranteeing safety and preventing excessive occupancy of the battery's internal space.

[0052] The foregoing describes only preferred embodiments of the present invention and does not limit it, and the present invention can have various modifications and changes for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should all be within the scope of protection of the present invention. [Industrial applicability]

[0053] The secondary battery of the present invention can be applied in the field of lithium battery technology. [Explanation of Symbols]

[0054] 1000:Electronic equipment 1001: Vehicle body 1002: Battery pack 100: Secondary battery 120: Electrode Assembly 120c: Winding center hole 122: Separator 122u: First separator terminal 122l: Second separator end 160: Polar pillar 200: Case 201: Negative electrode current collector plate 202: Positive electrode current collector plate 205:Aperture 220: Cover plate 109: Peripheral wall 111: End wall 113: Pressure-welded section 10: Negative electrode sheet 16: Negative electrode active material layer 16u: 1st negative terminal 16l: 2nd negative terminal 18: Negative electrode current collector 18a: Negative electrode coating area 18b: Anode uncoated area 18b1: Negative electrode connection area 18b2: Negative tab 18b21: Negative electrode tab transition section 18b22: Negative electrode tab body 20: Positive electrode sheet 26: Positive electrode active material layer 26u: 1st positive end 26l: 2nd positive end 28: Positive electrode current collector 28a: Positive electrode coating area 28b: Uncoated area of ​​the positive electrode 28b1: Positive electrode connection 28b2: Positive tab 28b21: Positive electrode tab transition section 28b22: Positive electrode tab body 32: Rolled edge 40: Insulating layer 40u: First insulating layer end 40l: End of second insulation layer D1: 1st direction D2:Second direction E11: First negative electrode tab transition endpoint E12: Second negative electrode tab transition endpoint E21: First positive electrode tab transition endpoint E22: Second positive electrode tab transition endpoint H1: Distance H2: distance H3: distance H4: Distance H6:Distance H7: Distance H8: Width H 122 :height

Claims

1. The electrode assembly includes a negative electrode sheet, a positive electrode sheet, and a separator placed between the negative electrode sheet and the positive electrode sheet. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, the negative electrode current collector includes a negative electrode coated region covered by the negative electrode active material layer and a negative electrode uncoated region not covered by the negative electrode active material layer, the direction from the negative electrode coated region to the negative electrode uncoated region is defined as the first direction, and the separator includes a first separator end in the first direction. Along the first direction, the uncoated negative electrode region includes a negative electrode tab and a negative electrode connection portion connected between the negative electrode tab and the negative electrode coated region, the negative electrode tab includes a negative electrode tab body and a negative electrode tab transition portion connected between the negative electrode connection portion and the negative electrode tab body, the negative electrode tab transition portion includes a first negative electrode tab transition endpoint connected to the negative electrode connection portion, the first negative electrode tab transition endpoint is the position where the tangent to the negative electrode tab transition portion intersects with the direction in which the negative electrode connection portion extends, A secondary battery characterized in that the distance over which the first negative electrode tab transition endpoint protrudes beyond the first separator end in the first direction is 0.5 to 2 mm.

2. The secondary battery according to claim 1, characterized in that the negative electrode active material layer includes a first negative pole in the first direction, and the distance over which the first negative electrode tab transition endpoint extends beyond the first negative pole in the first direction is 1.5 to 3 mm.

3. The secondary battery according to claim 2, characterized in that the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer includes a first positive electrode end in the first direction, and the distance by which the first negative electrode end extends beyond the first positive electrode end in the first direction is 1.0 to 1.5 mm.

4. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, the positive electrode current collector includes a positive electrode coated region covered by the positive electrode active material layer and a positive electrode uncoated region not covered by the positive electrode active material layer, the direction from the positive electrode coated region to the positive electrode uncoated region is defined as the second direction, and the second direction is the opposite direction to the first direction. Along the second direction, the uncoated positive electrode region includes a positive electrode tab and a positive electrode connection portion connected between the positive electrode tab and the positive electrode coated region, the positive electrode tab includes a positive electrode tab body and a positive electrode tab transition portion connected between the positive electrode connection portion and the positive electrode tab body, the positive electrode tab transition portion includes a first positive electrode tab transition endpoint connected to the positive electrode connection portion, the first positive electrode tab transition endpoint is the position where the tangent to the positive electrode tab transition portion intersects with the direction in which the positive electrode connection portion extends, The secondary battery according to claim 1, wherein the electrode assembly further includes an insulating layer, the insulating layer covers the positive electrode connection portion, and the width of the insulating layer in the second direction is 0.5 to 2.5 mm.

5. The secondary battery according to claim 4, characterized in that the negative electrode active material layer includes a second negative electrode end in the second direction, the insulating layer includes a first insulating layer end in the first direction, and the distance over which the second negative electrode end extends beyond the first insulating layer end in the second direction is 0.5 to 1 mm.

6. The secondary battery according to claim 5, characterized in that the insulating layer includes a second insulating layer end in the second direction, and the distance over which the second insulating layer end extends to the second negative pole end in the second direction is 0.5 to 1 mm.

7. The secondary battery according to claim 1, characterized in that the negative electrode active material layer includes a first negative pole in the first direction, and the distance over which the first separator end extends beyond the first negative pole in the first direction is 0.5 to 1.5 mm.

8. The case further comprises a case used to house the electrode assembly, the case including a circumferential side wall and an end wall connected to one end of the circumferential side wall, the other end of the circumferential side wall having an opening, the circumferential side wall adjacent to the opening having a pressure contact portion projecting inward, and the electrode assembly being positioned between the end wall and the pressure contact portion. The negative electrode tab faces the opening and is connected to the case via a negative electrode current collector plate, and the welding position between the negative electrode current collector plate and the circumferential wall is located on the side of the pressure-welded portion facing the electrode assembly. The secondary battery according to claim 4, characterized in that the secondary battery is a cylindrical battery.

9. A battery pack characterized by including a secondary battery according to any one of claims 1 to 8.

10. An electronic device characterized by including the battery pack described in claim 9.

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