Battery cell and battery

Abstract

The invention relates to the technical field of batteries, in particular to a battery cell and a battery, the battery cell comprises a first pole piece and a second pole piece, the first pole piece comprises a first current collector and a first pin extending from one side edge of the first current collector; the second pole piece comprises a second current collector and a second pin extending from the edge of one side of the second current collector; the first pin is connected with the edge of the first current collector through a first arc, and the second pin is connected with the edge of the second current collector through a second arc. The battery cell can enlarge the distance between the positive and negative tabs in a limited space range, so that the risk of short circuit caused by easy contact between the positive and negative tabs due to too close distance between the positive and negative tabs when the battery is subjected to a drop test, a transportation process or other external force conditions is avoided.

Description

Technical Field

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

[0002] With the increasing prominence of energy shortages and environmental pollution, lithium-ion batteries, with their advantages of high energy density, good cycle performance, and low self-discharge, have been widely used in many fields such as consumer electronics, new energy vehicles, and energy storage power stations.

[0003] In recent years, the rapid rise of small portable electronic devices such as smart glasses and smartwatches has driven the development of lithium-ion batteries towards miniaturization and narrower dimensions, which places higher demands on battery manufacturing processes.

[0004] The small and narrow batteries in the current technology have a small distance between the positive and negative tabs. When the positive and negative plates are misaligned, the positive and negative tabs are prone to contact, which can lead to a short circuit and cause safety risks such as battery fires, seriously affecting the development of small lithium-ion batteries. Summary of the Invention

[0005] To address the aforementioned technical problems in the prior art, this invention provides a battery cell and a battery. The battery cell of this invention can increase the distance between the positive and negative tabs within a limited space, thereby avoiding the risk of short circuits caused by the positive and negative tabs coming into contact with each other due to excessively close spacing during drop tests, transportation, or other external forces.

[0006] A first aspect of the present invention provides a battery cell, the battery cell including a first electrode and a second electrode, the first electrode including a first current collector and a first pin extending from one side edge of the first current collector, the second electrode including a second current collector and a second pin extending from one side edge of the second current collector; the first pin is connected to the edge of the first current collector by a first arc, and the second pin is connected to the edge of the second current collector by a second arc; in a first direction, the battery cell includes a first side and a second side disposed opposite to each other, the first pin being closer to the first side and the second pin being closer to the second side; In the first direction, the distance between the first pin and the second pin is W2, and W2 satisfies: 1mm≤W2≤2mm; The first arc includes a first endpoint and a second endpoint. The first endpoint is the connection point of the first arc with the extension line of the edge of the first pin, and the second endpoint is the connection point of the first arc with the extension line of the edge of the first current collector. The second arc includes a third endpoint and a fourth endpoint. The third endpoint is the connection point of the second arc with the extension line of the edge of the second pin, and the fourth endpoint is the connection point of the second arc with the extension line of the edge of the second current collector. In the first direction, the distance between the second endpoint and the fourth endpoint is W3, and W3 satisfies: 0.5mm≤W3≤1.5mm; wherein, W2 and W3 satisfy: 1.33≤W2 / W3≤2.

[0007] A second aspect of the present invention provides a battery comprising the cell and casing described in the first aspect of the present invention.

[0008] By employing the above technical solution, the present invention has at least the following advantages compared with the prior art: This invention provides a cell structure for small lithium-ion batteries. The cell connects the first pin to the edge of the first current collector via a first arc, and the second pin to the edge of the second current collector via a second arc. Simultaneously, it limits the distance between the second and fourth endpoints. This expands the distance between the roots of the first and second pins within a limited space, thus preventing short circuits caused by excessively close contact between the roots of the first and second pins during drop tests, transportation, or other external forces. This improves battery safety. Furthermore, by controlling the distance between the first and second pins, specifically the range W2 (W2 is greater than or equal to 1 mm), it also prevents excessively small distances from causing self-discharge, which could negatively impact the cell's cycle performance and lifespan.

[0009] Furthermore, by defining the relationship between the distance W3 between the second and fourth endpoints and the distance W2 between the pins, the distance between the pins is greater than the distance between the second and fourth endpoints. In other words, by widening the width of the roots of the first and second pins and controlling it within the aforementioned range, in addition to preventing the roots of the first and second pins from easily contacting each other and causing a short circuit, the current distribution at the roots of the first and second pins is also made more uniform, maximizing the utilization rate of the active material and improving heat distribution. Moreover, during drop tests or cell expansion, a wider width at the roots of the first and second pins can also relieve stress and prevent stress concentration.

[0010] Other features and advantages of the present invention will be described in detail in the following detailed description section.

[0011] 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

[0012] Figure 1 The diagram shown is a top view of the battery cell in one embodiment of the present invention.

[0013] Figure 2 The diagram shown is a partial structural schematic of a battery cell according to one embodiment of the present invention.

[0014] Figure 3 The diagram shown is a partial structural schematic of a battery cell according to one embodiment of the present invention.

[0015] Figure 4 The diagram shown is a partial structural schematic of a battery cell according to one embodiment of the present invention.

[0016] Figure 5 The figures shown are a schematic diagram (a) of the head of the battery and a top perspective view (b) of the head in one embodiment of the present invention.

[0017] Figure 6 The image shown is a top perspective view of the battery head in one embodiment of the present invention.

[0018] Figure 7 The diagram shown is a top view of the battery structure in one embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: First electrode 100, first current collector 110, first pin 120, first arc 130, first endpoint 131, second endpoint 132, first side 140, second side 150; Second pole piece 200, second current collector 210, second pin 220, second arc 230, third endpoint 231, fourth endpoint 232, third side 240, fourth side 250; Battery cell 10, housing 20, bottom shell 21, cover plate 22, side wall 23, first through hole 24, second through hole 25, second pole post 26, conductive part 261, straight part 262, insulating layer 27, first side wall 28, second side wall 29. Detailed Implementation

[0020] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the invention. Unless otherwise specified herein, data ranges include endpoints.

[0021] It should be noted that the numerical designations such as "first" and "second" in this invention are only used to distinguish different substances or methods of use, and do not represent a difference in order.

[0022] One embodiment of this application provides a battery cell, such as... Figure 1 As shown, the battery cell includes a first electrode 100 and a second electrode 200. In one specific example, the battery cell also includes a separator and an electrolyte. In another specific example, the first electrode is a negative electrode and the second electrode is a positive electrode.

[0023] The first electrode 100 includes a first current collector 110 and a first pin 120 extending from one side edge of the first current collector 110, and the second electrode 200 includes a second current collector 210 and a second pin 220 extending from one side edge of the second current collector 210.

[0024] In a specific example, such as Figure 1 As shown, the first pin 120 is integrally formed with the first current collector 110, meaning that the first pin 120 and the first current collector 110 are made of the same material. In another specific example, the second pin 220 is integrally formed with the second current collector 210, meaning that the second pin 220 and the second current collector 210 are made of the same material. The first and second pins are used to connect to an electrical adapter, thereby leading the current in the battery cell to an external device.

[0025] In one specific example, the first 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 first current collector may be, for example, 4μm-10μm (e.g., 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, or 10μm).

[0026] In one specific example, the first electrode further includes a first active layer located on the first current collector. The first active layer includes first active particles, which may include at least one of graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, spherical silicon-carbon, bulk silicon-carbon, Li-Al alloy, and lithium metal. In embodiments where the negative electrode active material layer includes a silicon-carbon composite, the mass fraction of silicon content is 5%-70% (e.g., 5%, 5.5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, or 70%).

[0027] In a specific example, the second current collector may be, for example, an aluminum foil, an aluminum alloy foil, or a composite current collector (e.g., an 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).

[0028] In one specific example, the second electrode further includes a second active layer located on the second current collector. The second active layer includes a second active material, which may include, for example, 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. In a further example, the second electrode also includes an insulating layer located on the second pin, the insulating layer being made of materials such as boehmite and alumina, extending from the boundary between the second current collector and the second pin to the second pin.

[0029] In one specific example, the battery cell is a stacked core formed by stacking a first electrode, a separator, and a second electrode. In a further specific example, the stacked core includes a topmost and a bottommost electrode along the thickness direction. The topmost and / or bottommost electrode may be a single-sided first electrode, which includes a first current collector and a first active layer on the side surface of the first current collector near the center of the battery cell.

[0030] In one specific example, the separator includes a base membrane and adhesive layers on both sides of the base membrane. In a further specific example, 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 one example, 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).

[0031] In one specific example, the battery cell also includes an electrolyte comprising a lithium salt and a solvent, wherein the solvent includes at least one selected from ethylene carbonate, diethyl carbonate, or fluoroethylene carbonate. In another specific example, the electrolyte also includes nitrile additives.

[0032] In one example, the content of the nitrile additive 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%.

[0033] In one example, the nitrile additive includes at least one of butadionitrile, adiponitrile, and 1,3,6-hexanetrionitrile.

[0034] In this invention, such as Figure 2 As shown, the first pin 120 is connected to the edge of the first current collector 110 via a first arc 130, and the second pin 220 is connected to the edge of the second current collector 210 via a second arc 230. In a specific example, both sides of the first pin 120 are connected to the two side edges of the first current collector 110 via the first arc 130; both sides of the second pin 220 are connected to the two side edges of the second current collector 210 via the second arc 230. In the first direction, the cell includes a first side and a second side disposed opposite to each other, as shown... Figure 2 As shown, the first pin 120 is close to the first side, and the second pin 220 is close to the second side. The first side and the second side are positioned opposite each other. That is, by placing the first pin close to the first side and the second pin close to the second side, the spacing between the first pin and the second pin is increased, preventing short circuits caused by contact between the first pin and the second pin. In the first direction, as... Figure 1 As shown, the distance between the first pin 120 and the second pin 220 is W2, and W2 satisfies: 1mm≤W2≤2mm. Specifically, by drawing a straight line parallel to the first direction, the shortest distance between the point where the straight line intersects the first pin and the second pin is W2.

[0035] Among them, such as Figure 2As shown, the first arc 130 includes a first endpoint 131 and a second endpoint 132. The first endpoint 131 is the connection point of the extension line of the first arc 130 and the edge of the first pin 120, and the second endpoint 132 is the connection point of the extension line of the first arc 130 and the edge of the first current collector 110; that is, the tangent point of the extension line of the first arc 130 and the edge of the first pin 120 or the tangent point of the extension line of the first arc 130 and the edge of the first current collector 110, that is, the connection point of the side of the first pin 120 and the first arc 130 and the connection point of the top edge of the first current collector 110 and the first arc 130.

[0036] Among them, such as Figure 2 As shown, the second arc 230 includes a third endpoint 231 and a fourth endpoint 232. The third endpoint 231 is the connection point of the extension line of the edge of the second arc 230 and the edge of the second pin 220. The fourth endpoint 232 is the connection point of the extension line of the edge of the second arc 230 and the edge of the second current collector 210, that is, the tangent point of the extension line of the edge of the second arc 230 and the edge of the second pin 220 or the tangent point of the extension line of the edge of the second arc 230 and the edge of the second current collector 210, that is, the connection point of the side of the second pin 220 and the second arc 230, and the connection point of the top edge of the second current collector 210 and the second arc 230.

[0037] like Figure 1 and Figure 2 As shown, in the first direction, the distance between the second endpoint 132 and the fourth endpoint 232 is W3, and W3 satisfies: 0.5mm ≤ W3 ≤ 1.5mm. That is, draw a vertical line perpendicular to the first direction passing through the second endpoint and a vertical line perpendicular to the first direction passing through the fourth endpoint. Along the first direction, the distance between the two vertical lines is the distance between the second endpoint and the fourth endpoint.

[0038] Among them, W2 and W3 satisfy: 1.33≤W2 / W3≤2.

[0039] The battery cell structure provided in this embodiment expands the distance between the second and fourth endpoints within the limited space of the first and second pins. This is achieved by connecting the first pin to the edge of the first current collector via a first arc and connecting the second pin to the edge of the second current collector via a second arc, while simultaneously limiting the distance between the second and fourth endpoints. This distance, i.e., the distance between the roots of the first and second pins, is increased within the limited space of the first and second pins. This avoids the risk of short circuits caused by the roots of the first and second pins coming into contact with each other when the battery is subjected to drop tests, transportation, or other external forces. This improves battery safety. Furthermore, by controlling the distance between the first and second pins, i.e., the range of W2, where W2 is greater than or equal to 1mm, it also prevents the distance between the first and second pins from being too small, which could easily lead to self-discharge and affect the cycle performance and lifespan of the battery cell.

[0040] Furthermore, by defining the relationship between the distance W3 between the second and fourth endpoints and the distance W2 between the pins, i.e., 1.33≤W2 / W3≤2, the distance between the pins is greater than the distance between the second and fourth endpoints. In other words, by widening the width of the roots of the first and second pins and controlling it within the aforementioned range, in addition to preventing the roots of the first and second pins from easily contacting each other and causing a short circuit, the current distribution at the roots of the first and second pins is also made more uniform, maximizing the utilization rate of the active material and improving heat distribution. Moreover, during drop tests or cell expansion, a wider width at the roots of the first and second pins can also relieve stress and prevent stress concentration.

[0041] In a specific example, such as Figure 1 and Figure 2 As shown, the first direction can be, for example, the width direction of the battery cell. In a specific example, the second direction can be, for example, the thickness direction of the battery.

[0042] In one possible implementation, such as Figure 2As shown, in the extension direction of the first pin 120, the distance between the first endpoint 131 and the edge of the first current collector 110 is a1, specifically, the perpendicular distance from the first endpoint 131 to the extension line of the edge of the first current collector 110. In the first direction, the distance between the second endpoint 132 and the edge of the first pin 120 is b1, which also refers to the perpendicular distance from the second endpoint 132 to the extension line of the edge of the first pin 120. Wherein, a1 and b1 satisfy: a1 / b1≥1.5, that is, the first arc 130 is an elliptical arc. The distance a1 between the first endpoint 131 and the edge of the first current collector 110, and the distance b1 between the second endpoint 132 and the edge of the first pin 120, are respectively the semi-major axis and semi-minor axis of the first arc. By controlling the relationship between the semi-major axis and semi-minor axis of the first elliptical arc, compared to the connection between the first pin and the first current collector via a rounded chamfer, the stress concentration at the corner of the first arc can be reduced, thereby increasing the tensile strength of the first pin, preventing breakage of the first pin, and improving the structural performance and service life of the battery cell.

[0043] In one possible implementation, such as Figure 2 As shown, in the extension direction of the second pin 220, the distance between the third endpoint 231 and the edge of the second current collector 210 is a2, specifically, the perpendicular distance from the third endpoint 231 to the extension line of the edge of the second current collector 210. In the first direction, the distance between the fourth endpoint 232 and the edge of the second pin 220 is b2, which also refers to the perpendicular distance from the fourth endpoint to the extension line of the edge of the second pin. Wherein, a2 and b2 satisfy: a2 / b2≥1.5. That is, the second arc 230 is an elliptical arc. The distance a1 between the third endpoint 231 and the edge of the second current collector 210, and the distance b1 between the fourth endpoint 232 and the edge of the second pin 220, are respectively the semi-major axis and semi-minor axis of the second arc. By controlling the relationship between the semi-major axis and semi-minor axis of the second elliptical arc, compared to the connection between the second pin and the second current collector via a rounded chamfer, the stress concentration at the corner of the second arc can be reduced, thereby increasing the tensile strength of the second pin, preventing breakage of the second pin, and improving the structural performance and service life of the battery cell.

[0044] In one possible implementation, such as Figure 3 As shown, at the first endpoint 131, the radius of curvature of the first arc 130 is R1; at the second endpoint 132, the radius of curvature of the first arc 130 is R2. R1 and R2 satisfy: R1 > R2; that is, the radius of curvature of the first arc at the connection point of the extension line of the first arc and the edge of the first pin is greater than the radius of curvature of the first arc at the connection point of the extension line of the first arc and the edge of the first current collector.

[0045] In another possible implementation, such as Figure 3 As shown, at the third endpoint 231, the radius of curvature of the second arc 230 is R3; at the fourth endpoint 232, the radius of curvature of the second arc 230 is R4, and R3 and R4 satisfy: R3 > R4; that is, the radius of curvature of the second arc at the connection point of the extension line of the edge of the second arc and the second pin is greater than the radius of curvature of the second arc at the connection point of the extension line of the edge of the second arc and the second collector.

[0046] Understandably, at the first endpoint, the radius of curvature of the first arc can be obtained by taking 3-5 points near the first endpoint, detecting the radius of curvature of the first arc, and then calculating the average radius of curvature as the radius of curvature of the first arc at the first endpoint.

[0047] By designing the first and second arcs as ellipses, where the major axis of the arc is parallel to the extension direction of the first pin and the minor axis is perpendicular to the extension direction of the first pin, the distance between the roots of the first and second pins is increased (which is also the minimum distance between the first and second pins). This prevents the chamfers of the roots of the first and second pins from contacting each other, thus avoiding short circuits in the cell. Simultaneously, this design also improves the tensile strength of the first and second pins, preventing short circuits that could reduce the cell's capacity.

[0048] In one possible implementation, such as Figure 4 As shown, in the extension direction of the first pin 120, the edge of the first electrode 100 extends beyond the edge of the second electrode 200. The distance between the edge of the first electrode 100 and the edge of the second electrode 200 is L4, and L4 satisfies: 0.5mm≤L4≤1.1mm. By having the edge of the first electrode extend beyond the edge of the second electrode, it is ensured that the first electrode completely covers the second electrode, maintaining the NP ratio and preventing lithium plating on the first electrode. Moreover, controlling the range of L4 can also prevent the size of the first electrode from becoming too large, which would lead to a decrease in the energy density of the cell. Furthermore, a2, b2, and L4 satisfy: a2≤L4, and / or b2≤L4; thus, under conditions where the cell is susceptible to external forces, such as drop tests or transportation, it can be ensured that the projection of the first electrode completely covers the second arc of the second electrode, thereby increasing the minimum distance between the first pin and the second pin and further preventing the first arc and the second arc from contacting each other and causing a short circuit.

[0049] In another possible implementation, such as Figure 4As shown, in the extension direction of the first pin 120, the distance between the edge of the first current collector 110 and the third endpoint 231 is L5, and L5 satisfies: L5≥0, thereby ensuring that the first electrode completely covers the second electrode and its third endpoint, and the first arc and the second arc are staggered in the length direction, thereby preventing the root of the first pin and the root of the second pin from contacting and short-circuiting.

[0050] In one possible implementation, such as Figure 1 As shown, in the first direction, the size of the first current collector 110 is W5, the size of the first pin 120 is W7, the size of the second current collector 210 is W6, and the size of the second pin 220 is W8, and W5, W6, W7, and W8 satisfy: 0.1≤W7 / W5≤0.3, and / or, 0.14≤W8 / W6≤0.33; by controlling the width ratio of the first current collector and the first pin, and the width ratio of the second current collector and the second pin, the structural strength of the first pin and the second pin within the narrow cell is ensured, and a certain distance is maintained between the first pin and the second pin to prevent short circuits.

[0051] In yet another specific example, such as Figure 1 As shown, the first current collector 110 includes a first side 140 near the first side, and the second current collector 210 includes a fourth side 250 near the second side; in the first direction, the dimension between the first side 140 and the fourth side 250 is W1, and W1 satisfies: 5mm≤W1≤10mm.

[0052] Another embodiment of this application provides a battery, such as Figure 5 As shown, the battery includes a casing 20 and the battery cell 10 in the above embodiments. In one specific example, the casing may be made of metal materials such as aluminum, titanium alloy, stainless steel, or copper. In another specific example, the shape of the casing may be square, rectangular, circular, angular, L-shaped, or stepped.

[0053] In one possible implementation, such as Figure 5 As shown, the housing 20 includes a bottom shell 21 and a cover plate 22. The bottom shell 21 includes a side wall 23, which forms an opening, and the cover plate 22 covers the opening. In a specific example, the side surface of the side wall near the cover plate protrudes outward to form a first flange edge, and the cover plate correspondingly forms a second flange edge. The first flange edge and the second flange edge are aligned and connected. Figure 5 As shown, the housing 20 has a first through hole 24 and a second through hole 25, wherein the second through hole is used for liquid injection. In one specific embodiment, the first and second through holes are located on the same side surface of the housing. In another specific embodiment, as shown... Figure 5 As shown, the first through hole 24 and the second through hole 25 are located on adjacent side surfaces of the housing 20.

[0054] like Figure 5 As shown, the battery includes a second terminal 26 passing through a first through-hole 24 and an insulating layer 27 located between the second terminal 26 and a sidewall 23. The second terminal 26 is connected to a second pin 220, and the first pin 120 is connected to the sidewall 23. The direct connection between the second terminal and the second pin, as well as the direct connection between the first pin and the sidewall, eliminates the need for pin bending as in existing technologies, reducing the bending space of the tabs and increasing the energy density of the cell.

[0055] In one possible implementation, the first and second through holes are located in the bottom shell or cover plate. In a specific example, such as... Figure 5 As shown, the second through hole 25 is located on the cover plate 22, and the first through hole 24 is located on the side wall of the bottom shell 21. In another specific embodiment, both the first through hole and the second through hole are located on the side wall of the bottom shell.

[0056] In one possible implementation, such as Figure 5 As shown, the second electrode post 26 includes a conductive portion 261 located within the first through hole 24 and a straight portion 262 connected to the conductive portion 261. An insulating layer 27 is located between the straight portion 262 and the sidewall 23. In one specific embodiment, the straight portion is located on the side surface of the sidewall closest to the battery cell, the insulating layer is located on the inner side of the sidewall, and the second pin is connected to the straight portion. This reduces the electrode post's footprint on external space, ensures a flat cross-section of the battery head, and improves the utilization rate of the battery's internal structure. In another specific embodiment, the straight portion includes a first straight portion and a second straight portion located at both edges of the conductive cloth. The insulating layer includes a first insulating layer located between the first straight portion and the sidewall, and a second insulating layer located between the second straight portion and the sidewall.

[0057] In one possible implementation, such as Figure 5 As shown, the conductive part 261 has a groove recessed inward on the side surface opposite to the straight part 262. The connection area of ​​the second electrode 26 and the second pin 220 is located within the groove. For example, the second electrode and the second pin can be connected by laser welding. This can be achieved by first attaching the second pin to the straight part, and then using a laser to perform laser welding deep into the groove. Figure 5 As shown, along the length of the battery cell, the distance from the bottom surface of the groove to the bottom surface of the second electrode post is T, and T satisfies: 0.05mm ≤ T ≤ 0.3mm. By forming a groove on the second electrode post, the thickness of the second electrode post at the welding point can be reduced, which is more conducive to welding and prevents incomplete or missed soldering.

[0058] In one possible implementation, such as Figure 6As shown, in the second direction, the second through-hole 25 at least partially overlaps with the first pin 120. In a specific example, the second direction refers to the thickness direction of the battery, and the second through-hole is formed on the cover plate. In the thickness direction, the projection of the second through-hole on the cover plate at least partially overlaps with the first pin, thereby making more efficient use of the head space of the battery and further improving the electrolyte wetting efficiency.

[0059] In one possible implementation, such as Figure 6 As shown, in the first direction, the size of the first pin 120 is L1, the distance between the edge of the first pin 120 near the first side and the edge of the second through hole 25 near the second side is L2, and the distance between the edge of the first pin 120 near the second side and the edge of the second through hole 25 near the first side is L3, satisfying: 0.2mm≤L2≤L1, 0.1≤L2 / L1≤1, and / or, 0.2mm≤L3≤L1, 0.1≤L3 / L1≤1. By setting the second through hole near the first tab, the second through hole is closer to the head space of the cell. Compared with the second tab and the second post, the head space on the first tab side is relatively larger, which is beneficial for electrolyte injection and improves the wetting efficiency of the electrolyte.

[0060] In one possible implementation, such as Figure 7 As shown, the bottom shell 21 includes a first sidewall 28 and a second sidewall 29, which are arranged opposite to each other along a first direction; the first electrode 100 includes a first side 140 and a second side 150, and the second electrode 200 includes a third side 240 and a fourth side 250, which are arranged opposite to each other along a first direction.

[0061] Among them, at least one of the first sidewall, second sidewall, first edge, second edge, third edge, and fourth edge is arc-shaped. The arc-shaped design allows for better matching with the dimensions of external electronic devices. In a further example, such as... Figure 7 As shown, the first sidewall 28, the first side 140 and the third side 240 are concentrically arranged, and / or the second sidewall 29, the second side 150 and the fourth side 250 are concentrically arranged. By concentrically arranging the corresponding sides of the first electrode 100, the second electrode 200 and the bottom shell 21, the energy density of the battery cell can be maximized.

[0062] In one possible implementation, such as Figure 7 As shown, the radius of the arc of the first sidewall 28 is R. 1 1. The radius of the arc with a first side of 140 is R. 1 3. Satisfies: 0.1mm≤R 1 3-R 11 ≤ 0.5 mm; in another specific example, the radius of the arc of the third side 240 is R. 1 5. The radius of the arc on the first side is R. 1 3. Satisfies: 0.15mm ≤ R 1 5-R 1 3≤0.5mm; In another specific example, the radius of the arc of the second sidewall 29 is R. 1 2. The radius of the arc on the second side is R. 1 4. Satisfies: 0.1mm≤R 1 2-R 1 4≤0.5mm; In another specific example, the radius of the arc of the fourth side 250 is R. 1 6. The radius of the arc on the second side is R. 1 4. Satisfies: 0.15mm ≤ R 1 4-R 1 6≤0.5mm. The radius of the arc of the first sidewall is greater than the radius of the arc of the first side of the first electrode, that is, the shell provides space for the expansion of the cell, allowing the cell to expand safely during charging and discharging without generating excessive internal pressure, effectively improving the cycle life of the cell. Moreover, this space can also provide a channel for the storage and wetting of electrolyte, ensuring that the entire cell, especially the central area, can be fully wetted.

[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 battery of the present invention.

[0065] Example 1 The following method is used in the preparation of the battery in this embodiment: (1) For the configuration of the first and second electrodes in this embodiment, please refer to [link to documentation]. Figures 1 to 4 : The battery cell includes a first electrode 100 and a second electrode 200; a stacked core formed by stacking the first electrode, the separator, and the second electrode; the first electrode 100 includes a first current collector 110 and a first pin 120 extending from one side edge of the first current collector 110; the second electrode 200 includes a second current collector 210 and a second pin 220 extending from one side edge of the second current collector 210; the first pin 120 is integrally formed with the first current collector 110 (made of copper foil, the thickness of the first current collector is 7μm), and the second pin 220 is integrally formed with the second current collector 210 (made of aluminum foil, the thickness of the first current collector is 10μm).

[0066] The two sides of the first pin 120 are connected to the two sides of the first current collector 110 via the first arc 130; the two sides of the second pin 220 are connected to the two sides of the second current collector 210 via the second arc 230; in the first direction, the distance W2 between the first pin 120 and the second pin 220 is 1.5mm.

[0067] The first arc 130 includes a first endpoint 131 and a second endpoint 132. The first endpoint 131 is the connection point of the extension line of the edge of the first arc 130 and the edge of the first pin 120, and the second endpoint 132 is the connection point of the extension line of the edge of the first arc 130 and the edge of the first current collector 110. The second arc 230 includes a third endpoint 231 and a fourth endpoint 232. The third endpoint 231 is the connection point of the extension line of the edge of the second arc 230 and the edge of the second pin 220, and the fourth endpoint 232 is the connection point of the extension line of the edge of the second arc 230 and the edge of the second current collector 210. In the first direction, the distance W3 between the second endpoint 132 and the fourth endpoint 232 is 1 mm; W2 / W3 = 1.5.

[0068] In the extension direction of the first pin 120, the distance a1 between the first endpoint 131 and the edge of the first current collector 110 is 0.5 mm; in the first direction, the distance b1 between the second endpoint 132 and the edge of the first pin 120 is 0.25 mm; a1 / b1 = 2.

[0069] In the extension direction of the second pin 220, the distance between the third endpoint 231 and the edge of the second current collector 210 is a2=0.5mm; in the first direction, the distance between the fourth endpoint 232 and the edge of the second pin 220 is b2=0.25mm; a2 / b2=2.

[0070] The radius of curvature R1 of the first arc 130 at the first endpoint 131 and the radius of curvature R2 of the first arc 130 at the second endpoint 132, R1=0.5mm and R2=0.25mm, satisfy: R1>R2; the radius of curvature R3 of the second arc 230 at the third endpoint 231 and the radius of curvature R4 of the second arc 230 at the fourth endpoint 232, R3=0.5mm and R4=0.25mm, satisfy: R3>R4.

[0071] In the extension direction of the first pin 120, the edge of the first electrode 100 extends beyond the edge of the second electrode 200, and the distance L4 between the edge of the first electrode 100 and the edge of the second electrode 200 is 0.8 mm, and a2, b2, and L4 satisfy: a2≤L4, b2≤L4; in the extension direction of the first pin 120, the distance L5 between the edge of the first current collector 110 and the third endpoint 231 is 0.3 mm≥0; in the first direction, the dimensions W5 of the first current collector 110, W7 of the first pin 120, W6 of the second current collector 210, and W8 of the second pin 220 are W5=8 mm, W6=7.3 mm, W7=2 mm, W8=2 mm, W7 / W5=0.25, and W8 / W6=0.27; in the first direction, the dimension W1 between the first side 140 and the fourth side 250 is 6 mm.

[0072] The first electrode further includes a first active layer on a first current collector, the first active layer including first active particles, the first active particles including graphite and silicon-carbon composite, the silicon content in the silicon-carbon composite being 30% by mass; the second electrode further includes a second active layer on a second current collector, the second active layer including a second active material, such as lithium cobalt oxide; the second electrode further includes an insulating layer on a second pin, the insulating layer being made of boehmite, the insulating layer extending from the boundary line between the second current collector and the second pin to the second pin; the separator includes a base film, a ceramic layer and a glue layer are sequentially formed on a first side of the base film, and a glue layer is formed on a second side, wherein the first side surface of the base film is disposed opposite to the positive electrode, the second side surface of the base film is disposed opposite to the negative electrode, and the thickness of the separator is 13μm. In addition, the battery cell also contains an electrolyte, which includes lithium salt and solvent. The solvent contains ethylene carbonate, diethyl carbonate, and fluoroethylene carbonate, as well as nitrile additives such as succinic acid, adiponitrile, and 1,3,6-hexanetrionitrile. Based on the total mass of the electrolyte, the total content of nitrile additives accounts for C3, which is 3.5%.

[0073] (2) For the casing and battery cell configuration of this embodiment, please refer to [link to relevant documentation]. Figures 5 to 7 : like Figure 5As shown, the housing 20 has a first through hole 24 and a second through hole 25. The first through hole 24 and the second through hole 25 are located on adjacent side surfaces of the housing 20, the second through hole 25 is located on the cover plate 22, and the first through hole 24 is located on the side wall of the bottom shell 21. The battery includes a second terminal 26 passing through the first through hole 24 and an insulating layer 27 located between the second terminal 26 and the side wall 23. The second terminal 26 is connected to the second pin 220, and the first pin 120 is connected to the side wall 23. The second terminal 26 includes a conductive part 261 located in the first through hole 24 and a straight part 262 connected to the conductive part 261. The insulating layer 27 is located between the straight part 262 and the side wall 23. The conductive part 261 has a groove recessed inward on the side surface opposite to the straight part 262, and the connection area of ​​the second terminal 26 and the second pin 220 is located in the groove. In the length direction of the cell, the distance T from the bottom surface of the groove to the bottom surface of the second electrode post is 0.1 mm; in the second direction, the second through hole 25 almost completely overlaps with the first pin 120.

[0074] In the first direction, the dimensions L1 of the first pin 120, the distance L2 between the edge of the first pin 120 near the first side and the edge of the second through hole 25 near the second side, and the distance L3 between the edge of the first pin 120 near the second side and the edge of the second through hole 25 near the first side satisfy: 0.2mm≤L2=1.5mm≤L1=2mm, L2 / L1=0.75, 0.2mm≤L3=1.5mm≤L1=2mm, L3 / L1=0.75.

[0075] The radius R of the arc of the first sidewall 28 1 1 = 25.67mm, the radius R of the first arc is 140. 1 3 = 26.07 mm, satisfying: R 1 3-R 1 1 = 0.4 mm, the radius R of the arc on the third side is 240. 1 5 = 26.47mm, the radius R of the first side arc is 140. 1 3. Satisfies: R 1 5-R 1 3 = 0.4 mm; the radius R of the arc of the second sidewall 29 1 2 = 34.3mm, the radius R of the second side's 150 arc. 1 4 = 33.9 mm, satisfying: R 1 2-R 1 4 = 0.4 mm; the radius of the arc on the fourth side (250) is R. 1 6 = 33.5mm, and the radius of the arc on the second side (150) is R. 1 4. Satisfies: R 1 4-R 1 6 = 0.4 mm.

[0076] Example 2 group This set of embodiments refers to the battery preparation method of Embodiment 1. The difference is that the distance W2 between the first pin 120 and the second pin 220 and the distance W3 between the second endpoint 132 and the fourth endpoint 232 are changed in the first direction, so that W2 / W3 is changed. See Table 1-1 for details.

[0077] Comparative Example 1 This comparative example is prepared according to the battery preparation method of Example 1. The difference is that the distance W2 between the first pin 120 and the second pin 220 and the distance W3 between the second endpoint 132 and the fourth endpoint 232 in the first direction are changed, so that W2 / W3 is changed. See Table 1-1 for details.

[0078] Table 1-1 In Table 1-1, except for W2 / W3, a2 / b2, and a2 / b2, which are dimensionless values, the values ​​of the other parameters are all in mm.

[0079] Example 3 Group This set of embodiments refers to the battery preparation method of Embodiment 1. The difference is that the size W5 of the first current collector 110 and the size W7 of the first pin 120 are changed in the first direction, so that W7 / W5 is changed. See Table 1-2 for details.

[0080] Example 4 group This set of embodiments refers to the battery preparation method of Embodiment 1. The difference is that the size W6 of the second current collector 210 and the size W8 of the second pin 220 are changed in the first direction, so that W8 / W6 is changed. See Table 1-2 for details.

[0081] Example 5 group This set of embodiments refers to the battery preparation method of Embodiment 1. The difference is that the size L1 of the first pin 120, the distance L2 between the edge of the first pin 120 near the first side and the edge of the second through hole 25 near the second side, and the distance L3 between the edge of the first pin 120 near the second side and the edge of the second through hole 25 near the first side are changed in the first direction, so that L2 / L1 and L3 / L1 are changed. See Table 1-2 for details.

[0082] Table 1-2 In Table 1-2, except for W7 / W5, W8 / W6, L2 / L1, and L3 / L1, which are dimensionless values, the values ​​of the other parameters are all in mm.

[0083] Example 6 group This set of embodiments follows the battery preparation method of Embodiment 1, except that the radius R of the arc of the first sidewall 28 is changed. 1 1. The radius R of the first arc with a radius of 140. 1 3. The radius R of the arc on the third side is 240. 1 5. The radius R of the arc of the second sidewall 29 1 2. The radius R of the second arc with a radius of 150. 1 4. The radius of the arc on the fourth side is R. 1 6, which makes R 1 3-R 1 1. R 1 5-R 1 3. R 1 2-R 1 4. R 1 4-R 1 6 has changed; see Table 1-3 for details.

[0084] All parameters in Table 1-3 are in mm.

[0085] Comparative Example 2 This comparative example is made in accordance with the battery preparation method of Example 1. The difference is that the two sides of the first pin 120 are not connected to the two sides of the first current collector 110 by an arc, but are directly connected by a right angle. The two sides of the second pin 220 are not connected to the two sides of the second current collector 210 by an arc, but are directly connected by a right angle.

[0086] Test case The batteries prepared in the above embodiments and comparative examples were subjected to the following tests: (1) Battery drop test pass rate: At 25℃, the lithium-ion battery was charged at a constant current of 0.5C to 4.5V, then charged at a constant voltage of 0.05C. After standing for 60 minutes, the voltage of the lithium-ion battery before the drop test was measured. The lithium-ion battery was placed in a fixture and dropped freely from a height of 1.5m on the ground using a drop device in the following order: head-tail-right corner of head-right corner of tail-left corner of head-left corner of tail (angle: 45±15°), repeated 4 times. After the drop test, the battery was left to stand at room temperature for 24 hours, and the voltage of the lithium-ion battery was measured and recorded. The appearance of the lithium-ion battery was checked and photographed before and after the test. The criteria for passing the drop test were: voltage drop <30mV, no fire or explosion of the battery. Ten samples were tested, and the number of batteries that passed was recorded as X, and the result was recorded as "X / 10". The test results are shown in Table 2.

[0087] Table 2 As shown in Table 2 above, the battery cell of the present invention can increase the distance between the positive and negative tabs within a limited space, which can avoid the distance between the positive and negative tabs becoming too close during transportation or other external forces, thereby avoiding the risk of short circuit caused by easy contact between the positive and negative tabs, and improving the battery's drop resistance and safety performance.

[0088] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A battery cell, characterized in that, The battery cell includes a first electrode and a second electrode. The first electrode includes a first current collector and a first pin extending from one side edge of the first current collector. The second electrode includes a second current collector and a second pin extending from one side edge of the second current collector. The first pin is connected to the edge of the first current collector by a first arc, and the second pin is connected to the edge of the second current collector by a second arc. In a first direction, the cell includes a first side and a second side disposed opposite to each other, with the first pin close to the first side and the second pin close to the second side; In the first direction, the distance between the first pin and the second pin is W2, and W2 satisfies: 1mm≤W2≤2mm; The first arc includes a first endpoint and a second endpoint. The first endpoint is the connection point of the first arc with the extension line of the edge of the first pin, and the second endpoint is the connection point of the first arc with the extension line of the edge of the first current collector. The second arc includes a third endpoint and a fourth endpoint. The third endpoint is the connection point of the second arc with the extension line of the edge of the second pin, and the fourth endpoint is the connection point of the second arc with the extension line of the edge of the second current collector. In the first direction, the distance between the second endpoint and the fourth endpoint is W3, and W3 satisfies: 0.5mm≤W3≤1.5mm; Wherein, W2 and W3 satisfy: 1.33≤W2 / W3≤2.

2. The battery cell according to claim 1, characterized in that, In the extension direction of the first pin, the distance between the first endpoint and the edge of the first current collector is a1, and in the first direction, the distance between the second endpoint and the edge of the first pin is b1, wherein a1 and b1 satisfy: a1 / b1≥1.5; And / or, In the extension direction of the second pin, the distance between the third endpoint and the edge of the second current collector is a2, and in the first direction, the distance between the fourth endpoint and the edge of the second pin is b2, wherein a2 and b2 satisfy: a2 / b2≥1.

5.

3. The battery cell according to claim 1 or 2, characterized in that, At the first endpoint, the radius of curvature of the first arc is R1; at the second endpoint, the radius of curvature of the first arc is R2, wherein R1 and R2 satisfy: R1 > R2; And / or, at the third endpoint, the radius of curvature of the second arc is R3; at the fourth endpoint, the radius of curvature of the second arc is R4, and R3 and R4 satisfy: R3 > R4.

4. The battery cell according to claim 2, characterized in that, In the extension direction of the first pin, the edge of the first electrode extends beyond the edge of the second electrode, and the distance between the edge of the first electrode and the edge of the second electrode is L4, and L4 satisfies: 0.5mm≤L4≤1.1mm; a2, b2, and L4 satisfy: a2≤L4, and / or b2≤L4; And / or, in the extension direction of the first pin, the distance between the edge of the first current collector and the third endpoint is L5, and L5 satisfies: L5≥0.

5. The battery cell according to claim 1, characterized in that, In the first direction, the size of the first current collector is W5, the size of the first pin is W7, the size of the second current collector is W6, and the size of the second pin is W8, and W5, W6, W7, and W8 satisfy: 0.1 ≤ W7 / W5 ≤ 0.3, and / or, 0.14 ≤ W8 / W6 ≤ 0.33; and / or, The first current collector includes a first side near the first side, and the second current collector includes a fourth side near the second side; in the first direction, the dimension between the first side and the fourth side is W1, and W1 satisfies: 5mm≤W1≤10mm.

6. A battery, characterized in that, The battery comprises the cell and casing as described in any one of claims 1-5.

7. The battery according to claim 6, characterized in that, The housing includes a bottom shell and a cover plate, the bottom shell includes a side wall forming an opening, and the cover plate covers the opening; The shell is formed with a first through hole and a second through hole; The battery includes a second terminal post passing through the first through hole and an insulating layer located between the second terminal post and the side wall. The second terminal post is connected to the second pin, and the first pin is connected to the side wall.

8. The battery according to claim 7, characterized in that, The first through hole and the second through hole are located in the bottom shell or the cover plate. And / or, the second pole post includes a conductive portion located within the first through hole and a straight portion connected to the conductive portion, the insulating layer being located between the straight portion and the sidewall; And / or, in the second direction, the second via at least partially overlaps with the first pin; And / or, in the first direction, the size of the first pin is L1, the distance between the edge of the first pin near the first side and the edge of the second through hole near the second side is L2, the distance between the edge of the first pin near the second side and the edge of the second through hole near the first side is L3, and the following conditions are met: 0.2mm≤L2≤L1, 0.1≤L2 / L1≤1, and / or, 0.2mm≤L3≤L1, 0.1≤L3 / L1≤1.

9. The battery according to claim 7, characterized in that, The conductive part has a groove formed by an inward recess on the side surface opposite to the straight part, and the connection area of ​​the second pole and the second pin is located in the groove. Along the length of the battery cell, the distance from the bottom surface of the groove to the bottom surface of the second electrode post is T, and T satisfies: 0.05mm≤T≤0.3mm.

10. The battery according to claim 7, characterized in that, The bottom shell includes a first sidewall and a second sidewall, the first electrode includes a first side and a second side, and the second electrode includes a third side and a fourth side; At least one of the first sidewall, the second sidewall, the first edge, the second edge, the third edge, and the fourth edge is arc-shaped; And / or, the first sidewall, the first edge, and the third edge are concentrically arranged; And / or, the second sidewall, the second side, and the fourth side are concentrically arranged; And / or, the radius of the arc of the first sidewall is R. 1 1. The radius of the arc on the first side is R. 1 3. Satisfies: 0.1mm≤R 1 3-R 1 1≤0.5mm; And / or, the radius of the arc of the third side is R. 1 5. The radius of the arc on the first side is R. 1 3. Satisfies: 0.15mm ≤ R 1 5-R 1 3≤0.5mm; And / or, the radius of the arc of the second sidewall is R. 1 2. The radius of the arc on the second side is R. 1 4. Satisfies: 0.1mm≤R 1 2-R 1 4≤0.5mm; And / or, the radius of the arc of the fourth side is R. 1 6. The radius of the arc on the second side is R. 1 4. Satisfies: 0.15mm ≤ R 1 4-R 1 6≤0.5mm.

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