Electrochemical device and electronic equipment

Abstract

This utility model discloses an electrochemical device and an electronic device. The electrochemical device includes an electrode assembly, which comprises a first electrode, a diaphragm, and a second electrode arranged in a stacked and wound configuration. The second electrode has the opposite polarity to the first electrode. The first electrode has multiple alternating straight regions and multiple corner regions along its winding direction. The first electrode includes a current collector and an active material layer disposed on at least one surface of the current collector. The active material layer on at least one surface of the current collector has a grooved region at at least a portion of the corner region. The grooved region has multiple grooves, which are spaced apart along the width direction of the first electrode and each groove extends along the length direction of the first electrode. In this utility model, the grooves at the corners of the electrode extend in accordance with the winding direction of the electrode. During the expansion and contraction of the electrode, this effectively reduces the mechanical stress at the corner area, lowers the risk of active material peeling and powder shedding, and improves the structural stability of the electrode.

Description

Technical Field

[0001] This utility model relates to the field of electrochemical energy storage technology, and in particular to an electrochemical device and electronic equipment. Background Technology

[0002] Lithium-ion batteries, which contain lithium elements (including metallic lithium, lithium alloys, lithium ions, lithium polymers, etc.) in an electrochemical system, are widely used in consumer electronics and other fields due to their outstanding advantages such as high energy density, long cycle life and low self-discharge rate.

[0003] In the lithium battery manufacturing process, the cathode electrode, separator, and anode electrode are stacked and wound together to form a core, which is the core energy storage unit of the lithium battery. Among them, the cathode electrode, as the key carrier for lithium ions to insert / deintercalate during charging and discharging, plays a decisive role in battery performance due to its surface structure design.

[0004] Currently, in order to effectively improve the electrolyte wetting effect, the industry generally uses laser drilling technology to process straight groove structures along the longitudinal direction (i.e., the width direction of the electrode) on the surface of the corner area of ​​the cathode electrode to facilitate ion transport.

[0005] However, during actual charge-discharge cycles, the electrode repeatedly expands and contracts, generating periodic mechanical stress within the electrode. Because the longitudinal grooves extending along the width of the electrode in existing technology do not match the expansion and contraction directions at the electrode corners, they cannot adequately meet the dynamic deformation requirements of the electrode, causing mechanical stress to accumulate in the corner areas. After long-term cycling, this accumulated mechanical stress damages the interface between the active material and the current collector at the electrode corners, causing active material peeling, leading to powder shedding, and ultimately reducing the stability of the electrode structure, severely impacting the cycle life and safety performance of the lithium battery. Utility Model Content

[0006] The main purpose of this invention is to propose an electrochemical device that effectively reduces mechanical stress at the corners of the electrode during the expansion and contraction process, thereby reducing the risk of active material peeling and powder shedding and improving the structural stability of the electrode.

[0007] To achieve the above objectives, this utility model proposes an electrochemical device, which includes an electrode assembly. The electrode assembly includes a first electrode, a diaphragm, and a second electrode that are stacked and wound around each other, wherein the polarity of the second electrode is opposite to that of the first electrode.

[0008] The first electrode has a plurality of alternating straight regions and a plurality of corner regions along its winding direction. The first electrode includes a current collector and an active material layer disposed on at least one side surface of the current collector. The active material layer on at least one side surface of the current collector is provided with grooved areas at at least a portion of the corner regions.

[0009] The grooving area is provided with multiple grooves, which are spaced apart along the width direction of the first electrode and each groove extends along the length direction of the first electrode.

[0010] Optionally, along the width direction of the first electrode, the grooved area overlaps with the central region of the first electrode.

[0011] Optionally, each of the scribing areas includes multiple sub-scribing areas, and the multiple sub-scribing areas are sequentially distributed along the width direction of the first electrode sheet;

[0012] The plurality of sub-slot regions include a first sub-slot region, which overlaps with the central region of the first electrode sheet, and along the width direction of the first electrode sheet, the groove spacing of the grooves in the first sub-slot region is smaller than the groove spacing of the grooves in the other sub-slot regions.

[0013] Optionally, the plurality of sub-slot regions further include a second sub-slot region and a third sub-slot region, wherein the second sub-slot region, the first sub-slot region and the third sub-slot region are distributed sequentially along the width direction of the first electrode sheet;

[0014] Along the width direction of the first electrode, the groove spacing of the groove in the first sub-groove area is L1, the groove spacing of the groove in the second sub-groove area is L2, and the groove spacing of the groove in the third sub-groove area is L3. L1, L2, and L3 satisfy: L2 > L1 and L1 < L3.

[0015] Optionally, L1, L2, and L3 satisfy the following conditions: 0.2mm≤L1≤0.8mm, 1mm≤L2≤2mm, and 1mm≤L3≤2mm.

[0016] Optionally, the width of the first electrode is A;

[0017] Along the width direction of the first electrode, the width of the first sub-slot area is B1, the width of the second sub-slot area is B2, and the width of the third sub-slot area is B3. B1, B2, and B3 satisfy: 0.3A≤B1≤0.8A, 0.1A≤B2≤0.3A, and 0.1A≤B3≤0.3A.

[0018] Optionally, along the width direction of the first electrode, there is a spacing M between two adjacent sub-slot regions, wherein M satisfies: 0.2mm≤M≤1mm.

[0019] Optionally, the active material layer on at least one side surface of the current collector is provided with a receiving groove, the receiving groove being used to expose a portion of the surface of the current collector;

[0020] The receiving groove is located between any two adjacent scribing areas, and extends from one side edge of the first electrode sheet toward the central region of the first electrode sheet along the width direction of the first electrode sheet.

[0021] Optionally, along the winding direction of the first electrode, one end of the first electrode is the winding start end located in the inner circle of the electrode assembly, and the other end is the winding end located in the outer circle of the electrode assembly.

[0022] The receiving groove is provided with a grooving area at one of the K1 consecutive corner areas facing the winding start end, and the receiving groove is provided with a grooving area at one of the K2 consecutive corner areas facing the winding end end.

[0023] The first electrode has N layers; when N is an even number, N, K1, and K2 satisfy: 1≤K1≤0.5*N-1, 1≤K2≤0.5*N-1; when N is an odd number, N, K1, and K2 satisfy: 1≤K1≤0.5*(N-1), 1≤K2≤0.5*(N-1).

[0024] Optionally, in the width direction of the first electrode, there is a first distance E1 between one edge of the active material layer and the groove closest to it, and a second distance E2 between the other edge of the active material layer and the groove closest to it, wherein E1 and E2 satisfy: 0≤E1≤3mm, 0≤E2≤3mm.

[0025] Optionally, along the width direction of the first electrode, the groove width is X, where X satisfies: 20μm≤X≤80μm; and / or,

[0026] Along the length of the first electrode, the length of the groove is W, where W satisfies: 5mm ≤ W ≤ 20mm; and / or,

[0027] The sum of the areas of the plurality of grooves in any of the grooved areas is S1, and the area of ​​the corner area corresponding to the grooved area is S2. S1 and S2 satisfy: 0.4% ≤ S1 / S2 ≤ 8%.

[0028] Optionally, the thickness of the active material layer is H2;

[0029] The groove depth is H1, and H1 satisfies: 0.3H2≤H1≤0.7H2, and / or, H2 satisfies: 20μm≤H2≤200μm.

[0030] Optionally, the groove is formed by a plurality of continuously arranged and interconnected micropores, the projection of which onto the thickness of the active material layer is circular, elliptical, fan-shaped or polygonal.

[0031] Optionally, the pore size of the micropore is D, wherein D satisfies: 5μm≤D≤20μm.

[0032] This invention also proposes an electronic device comprising the electrochemical apparatus described above.

[0033] In this electrochemical device, the first electrode has multiple alternating straight areas and multiple corner areas along its winding direction. The active material layer on at least one side surface of the current collector has a grooved area at at least part of the corner area. The grooved area has multiple grooves, which are spaced apart along the width direction of the first electrode and each groove extends along the length direction of the first electrode. That is, the grooves at the corners of the electrode extend in accordance with the winding direction of the electrode. Since the expansion and contraction of the electrode mainly occur along its winding direction, the grooves at the corners of the electrode can guide the periodic mechanical stress generated during the expansion and contraction of the electrode to be released naturally along the winding direction, effectively reducing the mechanical stress at the corners of the electrode, reducing the risk of active material peeling and powder shedding at the corners of the electrode, and improving the structural stability of the electrode. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the electrode assembly of an electrochemical device in one embodiment of the present invention;

[0035] Figure 2 for Figure 1 A schematic diagram of the structure of the first electrode of the electrode assembly in the embodiment from a certain perspective;

[0036] Figure 3 for Figure 1 A schematic diagram of the structure of the first electrode of the electrode assembly in the embodiment from another perspective;

[0037] Figure 4 for Figure 2 A schematic diagram of the grooved area in the embodiment;

[0038] Figure 5 for Figure 2 A partial structural schematic diagram of the active material layer of the first electrode in the embodiment;

[0039] Figure 6 for Figure 4A schematic diagram of the groove structure in the grooving area of ​​the embodiment;

[0040] Explanation of icon numbers:

[0041] 100 First Pole Film 200 diaphragm 300 Second pole plate 100P Straight area 100G Corner area 110 current collector 120 Active material layer 121 Grooving area 122 groove 120C Container slot 1211 Sub-slot area 12111 First sub-diversion area 12112 Second sub-diversion area 12113 Third sub-slot area 1221 micropores

[0042] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0043] The solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0044] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0045] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0046] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0047] This utility model provides an electrochemical device, referring to... Figures 1 to 3 The electrochemical device includes an electrode assembly, which includes a first electrode 100, a diaphragm 200, and a second electrode 300 that are stacked and wound around each other, with the second electrode 300 having the opposite polarity to the first electrode 100.

[0048] The first electrode 100 has a plurality of alternating straight regions 100P and a plurality of corner regions 100G along its winding direction. The first electrode 100 includes a current collector 110 and an active material layer 120 disposed on at least one side surface of the current collector 110. The active material layer 120 on at least one side surface of the current collector 110 is provided with grooved regions 121 at at least a portion of the corner regions 100G.

[0049] The grooving area 121 is provided with a plurality of grooves 122, which are spaced apart along the width direction of the first electrode 100 and each groove 122 extends along the length direction of the first electrode 100.

[0050] The electrochemical devices involved in this application include any device in which an electrochemical reaction occurs to convert chemical energy into electrical energy and vice versa. Specific, non-limiting embodiments include all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries, etc.

[0051] like Figure 1 As shown, the electrode assembly, as the basic structure of the electrochemical device, consists of a first electrode 100, a separator 200, and a second electrode 300. These three components are stacked and wound together in the order of "first electrode 100 - separator 200 - second electrode 300" to form a core structure. The second electrode 300 has the opposite polarity to the first electrode 100. Specifically, the first electrode 100 can be a cathode electrode (also called a positive electrode), and the second electrode 300 is an anode electrode (also called a negative electrode). The anode electrode serves as the source of lithium ions during battery discharge, undergoing a lithium ion release reaction. The cathode electrode serves as the source of lithium ions during battery charging, undergoing a lithium ion release reaction. The separator 200, located between the anode and cathode electrodes, plays a crucial role in isolating the electrodes and preventing direct contact and short circuits, while simultaneously allowing lithium ions to pass through, ensuring the smooth progress of the electrochemical reaction.

[0052] The first electrode 100 has multiple alternating straight regions 100P and multiple corner regions 100G along its winding direction (i.e., the circumferential direction of the electrode assembly). During the winding process, the section of the electrode parallel to the axis of the electrode assembly is the straight region 100P, and the section of the electrode bending with the curvature of the electrode assembly is the corner region 100G. The straight regions 100P and corner regions 100G are periodically alternating along the winding direction (e.g., two corner regions 100G are formed for each turn of winding).

[0053] like Figure 2 and Figure 3As shown, the first electrode 100 includes a current collector 110 and an active material layer 120. The current collector 110 is a conductive substrate, preferably aluminum foil, and its surface can be electrochemically etched or sandblasted to improve its adhesion to the active material layer 120. The active material layer 120 is coated on at least one side of the current collector 110, preferably both sides, to improve energy density. Its composition includes active material, conductive agent (such as carbon black, graphene), and binder (such as polyvinylidene fluoride PVDF).

[0054] The active material layer 120 on at least one side surface of the current collector 110 has a grooved area 121 provided in at least part of the corner area 100G. Specifically, it may be provided only in the corner area 100G where stress is easily accumulated, or in all corner areas 100G, depending on the battery capacity and cycle requirements.

[0055] The grooved area 121 is used to construct ion transport channels. Multiple grooves 122 are provided within this area, spaced apart along the width direction of the first electrode 100 (i.e., the axial direction of the electrode assembly), meaning there is a gap between adjacent grooves 122. Each groove 122 extends along the length direction of the first electrode 100 (i.e., the circumferential direction of the electrode assembly, consistent with the electrode winding direction). The extension length of the groove 122 is adapted to the arc length of the corner area 100G, typically covering or exceeding the entire arc length of the corner area 100G. The cross-sectional shape of the groove 122 can be rectangular, trapezoidal, or arc-shaped, depending on actual requirements.

[0056] During the charge-discharge cycle of a lithium battery, lithium ions migrate between the first electrode 100 and the second electrode 300. During charging, lithium ions are extracted from the active material layer 120 of the first electrode 100 (if it is the cathode), pass through the electrolyte and the separator 200, and are inserted into the active material layer 120 of the second electrode 300 (if it is the anode); the discharge process is the reverse. During this process, the active material layer 120 of the first electrode 100 undergoes volume changes due to the insertion / extraction of lithium ions, leading to expansion and contraction deformation of the electrode. Since the first electrode 100 has a wound structure, its expansion and contraction are mainly along the circumferential direction of the electrode assembly (i.e., the length direction of the first electrode 100). This is because the axial direction (electrode width direction) of the electrode assembly is more strongly constrained by the outer casing and the separator 200, while the circumferential direction (electrode length direction) is less constrained, resulting in greater deformation space.

[0057] In the grooved area 121 of the corner region 100G of the first electrode 100, multiple grooves 122 extend along the length of the electrode, perfectly aligning with the main deformation direction (length direction) of the electrode. When the electrode expands, the volume of the active material layer 120 increases, generating outward mechanical stress in the corner region 100G. This stress can be dispersed and transmitted along the extension direction (length direction) of the grooves 122. The presence of the grooves 122 is equivalent to forming a flexible buffer channel in the active material layer 120, preventing local stress accumulation in the corner region 100G. When the electrode contracts, the volume of the active material layer 120 decreases, generating inward mechanical stress in the corner region 100G. This stress can also be released through the extension direction of the grooves 122, preventing the active material layer 120 from wrinkling due to contraction or peeling off from the current collector 110.

[0058] The groove 122, extending along its length, provides a channel for both electrolyte wetting and lithium ion transport. The electrolyte can quickly penetrate the 100G active material layer 120 in the corner area through the groove 122, improving wetting uniformity. During migration, lithium ions can flow along the extension direction of the groove 122, reducing bends in the transport path and lowering ion transport impedance. Furthermore, the spacing of the grooves 122 (along the width direction) ensures that an excessive number of grooves 122 prevents the electrode structure from becoming fragile.

[0059] That is, in the electrochemical device of this embodiment, the groove 122 at the corner of the electrode extends in accordance with the winding direction of the electrode. Since the expansion and contraction of the electrode mainly occur along its winding direction, the groove 122 at the corner of the electrode can guide the periodic mechanical stress generated during the expansion and contraction of the electrode to be released naturally along the winding direction, effectively reducing the mechanical stress at the corner of the electrode, reducing the risk of active material peeling and powder shedding at the corner of the electrode, and improving the structural stability of the electrode.

[0060] In some embodiments, refer to Figures 2 to 4 Along the width direction of the first electrode 100, the grooved area 121 overlaps with the central region of the first electrode 100. The central region of the first electrode 100 refers to the middle section on the active material layer 120 along the width direction of the electrode, where there is a gap between it and the two side edges. Specifically, if the total width of the first electrode 100 is P, the gap between the central section and one of its side edges is p1, and the gap between the central section and the other side edge is p2, the width of the central section is P-p1-p2, and the central section covers the center line of the width direction of the first electrode 100.

[0061] The way in which the grooved area 121 overlaps with the central area can be along the width direction of the first electrode 100, where the starting end of the grooved area 121 does not exceed the starting side of the central area, and the ending end of the grooved area 121 does not exceed the ending side of the central area; or, a portion of the grooved area 121 extends beyond the central area, but the core portion overlaps with the central area, depending on the actual situation.

[0062] In particular, the electrolyte wetting distance is furthest in the central region near the corner of the first electrode 100, resulting in relatively less electrolyte storage. Therefore, by setting the grooved area 121 to overlap with the central region of the first electrode 100, the grooves 122 in the grooved area 121 can provide electrolyte storage space and ion transport channels for the central region, thereby increasing the CB value of the central region, effectively alleviating the local polarization problem, and improving lithium plating at the corner.

[0063] In some embodiments, refer to Figures 2 to 4 Each grooving area 121 includes multiple sub-grooving areas 1211, which are sequentially distributed along the width direction of the first electrode 100.

[0064] The plurality of sub-slot regions 1211 include a first sub-slot region 12111, which overlaps with the central region of the first electrode 100. Along the width direction of the first electrode 100, the groove spacing of the grooves 122 in the first sub-slot region 12111 is smaller than the groove spacing of the grooves 122 in the other sub-slot regions 1211.

[0065] Along the width direction of the first electrode 100, the grooving area 121 of the corner area 100G is divided into multiple independent sub-grooving areas 1211, which are sequentially distributed along the width direction of the first electrode 100 (adjacent sub-grooving areas 1211 can be seamlessly connected or spaced apart). For example, the number of sub-grooving areas 1211 can be three or five, etc., and this embodiment does not limit this. The dimensional parameters such as the region length, region width, and region area of ​​different sub-grooving areas 1211 can be relative or unequal, depending on actual needs, and this embodiment does not limit this. Each sub-grooving area 1211 is processed with multiple grooves 122, and the specific number of grooves 122 is set according to actual needs.

[0066] Multiple sub-groove regions 1211 include a first sub-groove region 12111 (which can be defined as a densely grooved region) that overlaps with the central region of the first electrode 100. Along the width direction of the first electrode 100, the groove spacing of the grooves 122 in the first sub-groove region 12111 is smaller than the groove spacing of the grooves 122 in the remaining sub-groove regions 1211 (which can be defined as sparsely grooved regions). For example, there are three sub-groove regions 1211, with the first sub-groove region 12111 located in the central region. The groove spacing of the grooves 122 in the first sub-groove region 12111 is smaller than the groove spacing of the grooves 122 in the other two sub-groove regions 1211. As for the remaining sub-groove regions 1211 other than the first sub-groove region 12111, the groove spacing of the grooves 122 between the sub-groove regions 1211 can be the same or different; this embodiment does not impose any restrictions on this. The groove spacing described herein is the distance between the edges of two adjacent grooves 122 along the width direction of the first electrode 100. Optionally, for each sub-groove region 1211, the groove spacing between any two adjacent grooves 122 within the region is equal. The so-called equality can be completely equal or approximately equal, that is, slight errors are allowed.

[0067] The specific mechanism of the zoning and slotting at the corner of the electrode sheet can be as follows:

[0068] Densely grooved area (central region in the width direction of the electrode): This region (i.e., the first sub-grooving area 12111) has small groove spacing and high groove density (a large number of grooves 122 per unit area), which can provide more electrolyte storage space and ion transport channels.

[0069] Sparse groove area (non-central area in the direction of electrode width): As the distance from the central area increases, the electrolyte storage space requirement gradually decreases. By increasing the groove spacing of grooves 122 to reduce the number of grooves 122, the integrity of the active material layer 120 structure can be avoided by leaving the channels empty (too many grooves 122 will reduce the mechanical strength of the electrode).

[0070] Through a zoned and grooved design, the supply of electrolyte storage space and ion transport channels on the electrode surface is precisely matched with the demand in different areas. Specifically, the corners of the electrode employ a zoned and grooved design with varying groove spacing 122 between zones. Ion transport channels are densely distributed in the central area along the width of the electrode, while they are relatively sparse in other areas. This design aligns with the ion concentration and electrolyte storage distribution characteristics on the electrode surface, achieving a match and balance between the supply and demand of ion transport channels and electrolyte storage space, thus contributing to improved performance of the electrochemical device.

[0071] The number of sub-slots 1211 can be three, for example:

[0072] In some embodiments, refer to Figures 2 to 4 The multiple sub-slot regions 1211 also include a second sub-slot region 12112 and a third sub-slot region 12113, which are distributed sequentially along the width direction of the first electrode 100.

[0073] Along the width direction of the first electrode 100, the groove spacing of the groove 122 in the first sub-groove area 12111 is L1, the groove spacing of the groove 122 in the second sub-groove area 12112 is L2, and the groove spacing of the groove 122 in the third sub-groove area 12113 is L3. L1, L2, and L3 satisfy: L2 > L1 and L1 < L3.

[0074] Specifically, among the multiple sub-groove regions 1211 divided on the active material layer 120 of the corner region 100G of the first electrode 100, the second sub-groove region 12112, the first sub-groove region 12111, and the third sub-groove region 12113 are sequentially distributed along the width direction of the first electrode 100. For example, from the edge position on one side (such as the top side) of the electrode to the edge region on the other side, the second sub-groove region 12112, the first sub-groove region 12111, and the third sub-groove region 12113 are sequentially distributed. Adjacent sub-groove regions 1211 are seamlessly connected (or spaced apart).

[0075] Let the groove spacing of the grooves 122 in the first sub-groove area 12111, the second sub-groove area 12112, and the third sub-groove area 12113 be L1, L2, and L3, respectively. The three satisfy L2 > L1 and L1 < L3. The specific parameters need to be designed in conjunction with the ion concentration on the electrode surface and the electrolyte storage distribution, following the principle that the ion concentration and electrolyte storage amount are positively correlated with the density of the groove 122.

[0076] The core principle of this embodiment lies in the gradient ion transport channel and electrolyte storage space. By designing the difference in the gap between the cells with L2 > L1 and L1 < L3, the density of the ion transport channel from the middle region of the electrode to the two side edges is increased, which precisely matches the distribution characteristics of ion concentration and electrolyte storage from high to low.

[0077] In some embodiments, L1, L2, and L3 satisfy the following conditions: 0.2mm≤L1≤0.8mm, 1mm≤L2≤2mm, and 1mm≤L3≤2mm.

[0078] For example, the groove spacing L1 of the groove 122 in the first sub-groove area 12111 can be 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm or 0.8mm, or within the range of any two of the above values.

[0079] The groove spacing L2 of the groove 122 in the second sub-groove area 12112 can be 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm or 2mm, or within the range of any two of the above values.

[0080] The groove spacing L3 of the groove 122 in the third sub-grooving area 12113 can be 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm or 2mm, or within the range of any two of the above values.

[0081] In some embodiments, the width of the first electrode 100 is A;

[0082] Along the width direction of the first electrode 100, the width of the first sub-slot region 12111 is B1, the width of the second sub-slot region 12112 is B2, and the width of the third sub-slot region 12113 is B3. B1, B2, and B3 satisfy: 0.3A≤B1≤0.8A, 0.1A≤B2≤0.3A, and 0.1A≤B3≤0.3A.

[0083] Based on the gradient design of the three sub-slot regions 1211, a quantitative constraint is added on the width of the sub-slot region 1211 and the total width A of the first electrode 100, clarifying the coverage range of each sub-slot region 1211 along the width direction of the electrode, as follows:

[0084] Slot width definition: Here, “slot width 1211” refers to the length (i.e., coverage size) of each slot 1211 along the width direction of the first electrode 100. Let the width of the first slot 12111 be B1, the width of the second slot 12112 be B2, and the width of the third slot 12113 be B3.

[0085] 0.3A≤B1≤0.8A: The first sub-slot region (dense region) needs to cover the high-ion / high-current core region along the electrode width. A percentage below 0.3A will not completely cover the demand area near the tab, leading to polarization; a percentage above 0.8A will encroach on the active material space, increasing capacity loss. 0.1A≤B2≤0.3A, 0.1A≤B3≤0.3A: The second and third sub-slot regions (sparse regions) only need to cover the low-demand areas on both sides. A percentage below 0.1A will result in insufficient electrolyte wetting; a percentage above 0.3A will result in redundant slotting, wasting active material. Furthermore, B1+B2+B3≤A (to avoid exceeding the electrode width) and B2≈B3 (error ≤0.05A) must be satisfied to ensure symmetrical performance along the electrode width.

[0086] In some embodiments, along the width direction of the first electrode 100, there is a spacing M between two adjacent sub-grooves 1211, where M satisfies: 0.2mm≤M≤1mm.

[0087] For example, along the width direction of the first electrode 100, the spacing M between two adjacent sub-slot areas 1211 can be 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm, or within the range of any two of the above values.

[0088] In some embodiments, the active material layer 120 on at least one side surface of the current collector 110 is provided with a receiving groove 120C, which is used to expose a portion of the surface of the current collector 110.

[0089] The receiving groove 120C is located between any two adjacent slotted areas 121, and extends from one side edge of the first electrode 100 toward the central region of the first electrode 100 along the width direction of the first electrode 100.

[0090] In this embodiment, the active material layer 120 on one or both surfaces of the current collector 110 is provided with a receiving groove 120C. The receiving groove 120C, also known as the tab mounting groove, penetrates the active material layer 120 along its thickness direction, exposing part of the surface of the current collector 110. The size of the receiving groove 120C is adapted to the tab (which matches the polarity of the first electrode 100). The tab can be embedded in the receiving groove 120C and connected to the current collector 110 to realize the current conduction / conduction. The connection method can be welding (such as laser welding, ultrasonic welding), etc., including but not limited to these methods. The receiving groove 120C is located between any two adjacent grooved areas, that is, the receiving groove 120C is located at a flat area 100P, and the corner areas 100G on both sides of the flat area 100P are respectively provided with grooved areas 121, so that the receiving groove 120C is located between the two adjacent grooved areas 121. Furthermore, along the width direction of the first electrode 100, the receiving groove 120C extends from one side edge of the first electrode 100 toward the central region of the first electrode 100.

[0091] During the charging and discharging process of the electrochemical device, the current is introduced into / outlet from the current collector 110 through the tab. Because the current collector 110 has a certain resistance, a voltage drop will occur when the current is transmitted from the tab to both ends of the electrode (i.e., the starting end and the ending end of the winding). This results in the current density on the electrode surface exhibiting a distribution characteristic of "high in the tab area and low in the edge area". At the same time, lithium ions need to migrate in the active material layer 120 to complete the insertion / extraction reaction. The concentration gradient is consistent with the current density distribution, that is, the ion consumption / generation rate is high near the tab and the concentration requirement is high, while the opposite is true in the areas at both ends of the electrode.

[0092] The receiving groove 120C is located between two adjacent grooved areas 121. When lithium ions at the tab migrate to the grooved areas 121 on both sides, they can be rapidly transported and diffused through the ion transport channels constructed by the grooves 122 in the grooved areas 121.

[0093] In some embodiments, refer to Figure 2 and Figure 3 Along the winding direction of the first electrode 100, one end of the first electrode 100 is the winding start end located in the inner ring of the electrode assembly, and the other end is the winding end located in the outer ring of the electrode assembly.

[0094] A grooving area 121 is provided at the K1 consecutive corner areas 100G on the side of the receiving groove 120C facing the winding start end, and a grooving area 121 is provided at the K2 consecutive corner areas 100G on the other side of the receiving groove 120C facing the winding end.

[0095] The first electrode 100 has N layers; when N is even, N, K1, and K2 satisfy: 1≤K1≤0.5*N-1, 1≤K2≤0.5*N-1; when N is odd, N, K1, and K2 satisfy: 1≤K1≤0.5*(N-1), 1≤K2≤0.5*(N-1).

[0096] In this embodiment, the range of the number (K1, K2) of the grooving areas 121 on both sides of the receiving groove 120C is related to the number of layers N formed by the winding of the first electrode 100. Specifically, the number of layers N of the first electrode 100 can refer to the number of complete layers in the thickness direction formed by the first electrode 100 after winding (two layers in one winding), excluding the quarter turn at the winding end (such as incomplete layers where the outer ring only covers 1 / 2 of the width of the electrode assembly after winding are not included in N).

[0097] Along the winding direction of the first electrode 100, the corner regions 100G on both sides of the receiving groove 120C are continuously distributed in a ring. That is, on the side of the receiving groove 120C facing the winding start end (inner ring), the corner regions 100G are arranged continuously in sequence along the direction of receiving groove 120C → inner ring (denoted as the first inner corner region 100G, the second inner corner region 100G, ..., the K1 inner corner region 100G); on the side of the receiving groove 120C facing the winding end end (outer ring), the corner regions 100G are arranged continuously in sequence along the direction of receiving groove 120C → outer ring (denoted as the first outer corner region 100G, the second outer corner region 100G, ..., the K2 outer corner region 100G), and there are no discrete or intermittently distributed corner regions 100G. K1 is the number of corner areas 100G of the continuously set grooved areas 121 on the side of the receiving groove 120C facing the winding start end; K2 is the number of corner areas 100G of the continuously set grooved areas 121 on the side of the receiving groove 120C facing the winding end end; K1 and K2 are both positive integers (≥1, to ensure that at least one grooved area 121 on both sides of the receiving groove 120C achieves ion transport).

[0098] Specifically, there are two scenarios: when N is even or odd.

[0099] Scenario 1: When N is an even number (e.g., N = 12, 14, 16, 18, 20), 1 ≤ K1 ≤ 0.5 * N - 1, and 1 ≤ K2 ≤ 0.5 * N - 1. Taking N = 20 as an example, 1 ≤ K1 ≤ 9 and 1 ≤ K2 ≤ 9. That is, when the first electrode 100 has 20 layers, the receiving groove 120C facing the winding start end has K1 consecutive corner areas 100G with grooved areas 121 respectively. K1 can be 1, 2, 3, 4, 5, 6, 7, 8, or 9. The receiving groove 120C facing the winding end end has K2 consecutive corner areas 100G with grooved areas 121 respectively. K2 can be 1, 2, 3, 4, 5, 6, 7, 8, or 9, depending on the actual needs.

[0100] Scenario 2: When N is an odd number (e.g., N = 13, 15, 17, 19, 21), 1 ≤ K1 ≤ 0.5 * (N-1), and 1 ≤ K2 ≤ 0.5 * (N-1). Taking N = 21 as an example, 1 ≤ K1 ≤ 10, and 1 ≤ K2 ≤ 10. That is, when the first electrode 100 has 21 layers, the receiving groove 120C facing the starting end of winding has K1 consecutive corner areas 100G with grooved areas 121 respectively. K1 can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. The receiving groove 120C facing the ending end of winding has K2 consecutive corner areas 100G with grooved areas 121 respectively. K2 can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, depending on the actual needs.

[0101] In some embodiments, in the width direction of the first electrode 100, there is a first distance E1 between one side edge of the active material layer 120 and the groove 122 closest to it, and there is a second distance E2 between the other side edge of the active material layer 120 and the groove 122 closest to it. E1 and E2 satisfy: 0≤E1≤3mm, 0≤E2≤3mm.

[0102] Along the width direction of the first electrode 100 (perpendicular to the distribution direction of the grooved area 121), the active material layer 120 has two side edges. The edge closer to the width direction of the electrode is defined as the first side edge of the active material layer 120, and the other side edge is defined as the second side edge of the active material layer 120.

[0103] E1 is the straight-line distance between the first side edge of the active material layer 120 and the groove 122 on the corresponding side of the grooved area 121 (one side of the grooved area 121 along the width direction of the electrode); E2 is the straight-line distance between the second side edge of the active material layer 120 and the groove 122 on the corresponding side of the grooved area 121 (the other side of the grooved area 121 along the width direction of the electrode).

[0104] Optionally, E1 and E2 must satisfy 0≤E1≤3mm and 0≤E2≤3mm. For example, E1 and E2 can be 1mm, 2mm, or 3mm, or fall within the range of any two of the above values. That is, in the width direction of the first electrode 100, the opposite two sides of the active material layer 120 maintain a distance from the groove 122 closest to it in the grooving area 121. This area is left blank without groove 122, retaining only the complete active material layer 120.

[0105] In some embodiments, along the width direction of the first electrode 100, the groove width of the groove 122 is X, where X satisfies: 20μm≤X≤80μm; and / or,

[0106] Along the length of the first electrode 100, the length of the groove 122 is W, where W satisfies: 5mm ≤ W ≤ 20mm; and / or,

[0107] The sum of the areas of the multiple grooves 122 in any grooving area 121 is S1, and the area of ​​the corner area 100G corresponding to the grooving area 121 is S2. S1 and S2 satisfy: 0.4% ≤ S1 / S2 ≤ 8%.

[0108] For example, along the width direction of the first electrode 100, the groove width X of the groove 122 can be 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, or 80μm, or fall within the range of any two of the above values. By limiting the groove width of the groove 122 to a range of 20μm to 80μm, the groove width of the groove 122 is kept moderate, which can both prevent the groove width of the groove 122 from being too narrow, thus avoiding an increase in ion transport resistance, and prevent the groove width of the groove 122 from being too wide, thus avoiding a decrease in the strength of the electrode structure.

[0109] For example, such as Figure 5 As shown, along the length direction of the first electrode 100, the length W of the groove 122 can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm or 20μm, or within the range of any two of the above values.

[0110] For example, for any grooving area 121, let the sum of the areas of all grooves 122 in the grooving area 121 be S1 (the area of ​​a single groove 122 = the length of the groove 122 along the length of the electrode × the width along the width direction, and the sum of the areas of multiple grooves 122); the area of ​​the corner area 100G corresponding to the grooving area 121 is S2 (the arc length projection of the corner area 100G along the length of the electrode × the total width along the width direction, that is, the complete projected area of ​​the corner area 100G on the surface of the first electrode 100). The sum of the areas of multiple grooves 122 in the grooving area 121, S1, can be 0.4%S2, 0.7%S2, 1%S2, 1.5%S2, 2%S2, 3%S2, 4%S2, 5%S2, 6%S2, 6.5%S2, 7%S2, 7.5%S2 or 8%S2, or be within the range of any two of the above values. S1 and S2 satisfy 0.4% ≤ S1 / S2 ≤ 8%. Wherein: the lower limit of 0.4% ensures that the total area of ​​the groove 122 is sufficient to provide electrolyte storage space and ion transport channels, avoiding intensified polarization due to insufficient channels; the upper limit of 8% prevents the area of ​​the groove 122 from being too large and crowding out the active material layer 120, avoiding capacity loss exceeding the threshold and a decrease in the mechanical strength of the electrode.

[0111] In some embodiments, refer to Figure 5 The thickness of the active material layer 120 is H2;

[0112] The groove depth of groove 122 is H1, which satisfies: 0.3H2≤H1≤0.7H2, and / or, H2 satisfies: 20μm≤H2≤200μm.

[0113] For example, the thickness H2 of the active material layer 120 refers to the thickness of the active material layer 120 coated on one side of the current collector 110. The groove depth H1 of the groove 122 can be 0.3H2, 0.4H2, 0.5H2, 0.6H2, or 0.7H2, or fall within any two of these values. By limiting the groove depth H1 of the groove 122 to the range of 0.3H2 to 0.7H2, the groove depth of the groove 122 is kept moderate, avoiding both insufficient liquid storage space due to excessively shallow groove depth and decreased mechanical strength of the electrode due to excessively deep groove depth. For example, the thickness H2 of the active material layer 120 can be 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm or 200μm, or within the range of any two of the above values.

[0114] In some embodiments, refer to Figure 6 The groove 122 is formed by a plurality of continuously arranged and interconnected micropores 1221. The projection of the micropores 1221 onto the thickness direction of the active material layer 120 is circular, elliptical, fan-shaped, or polygonal. To further improve the ion transport efficiency and structural anti-expansion toughness of the groove 122, the groove 122 is formed by a plurality of continuously arranged and interconnected micropores 1221. The micropores 1221 are arranged sequentially along the length direction of the groove 122, and adjacent micropores 1221 partially overlap or are directly connected to form a continuous microchannel. Traditional grooves 122 are only single macrochannels, and ion transport depends on diffusion from the inner wall of the groove 122 to the active material layer 120. However, the micropores 1221 form a secondary channel. The macro-groove 122 guides the long-distance transport of ions, while the micropores 1221 further shorten the diffusion path and improve the ion diffusion efficiency. The projection of the micropores 1221 onto the thickness of the active material layer 120 is circular, elliptical, fan-shaped, or polygonal. The polygon can be triangular, rectangular, hexagonal, etc., and this embodiment does not impose any restrictions on this.

[0115] In some embodiments, the pore size of the micropore 1221 is D, where D satisfies: 5μm ≤ D ≤ 20μm. Exemplarily, the pore size D of the micropore 1221 can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, or 20μm, or fall within the range of any two of the aforementioned values.

[0116] This utility model embodiment also proposes an electronic device, which includes the electrochemical device described in the foregoing embodiments. The specific structure of the electrochemical device is as described in the above embodiments. Since this electronic device adopts all the technical solutions of all the above embodiments, it has at least all the technical effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0117] The electronic device described in this application is not particularly limited and can be any electronic device known in the prior art. The electrochemical device described in this application is also not particularly limited in its use and can be used in any electronic device known in the prior art. According to some embodiments of this application, the electronic devices include, but are not limited to, mobile phones, smartphones, laptops, tablets, wearable devices, smartwatches, smart bracelets, smart glasses, power banks, televisions, game consoles, game controllers, digital cameras, smart speakers, headphones, keyboards, mice, monitors, drones, audio equipment, home appliances, toys, power tools, automobiles, motorcycles, electric bicycles, bicycles, robots, and robotic dogs.

[0118] The above description is only a part or preferred embodiment of this utility model. Neither the text nor the drawings should limit the scope of protection of this utility model. All equivalent structural transformations made using the content of this utility model specification and drawings under the overall concept of this utility model, or direct / indirect applications in other related technical fields, are included within the scope of protection of this utility model.

Claims

1. An electrochemical device, characterized in that, The device includes an electrode assembly comprising a first electrode, a diaphragm, and a second electrode arranged in a stacked and wound manner, wherein the polarity of the second electrode is opposite to that of the first electrode. The first electrode has a plurality of alternating straight regions and a plurality of corner regions along its winding direction. The first electrode includes a current collector and an active material layer disposed on at least one side surface of the current collector. The active material layer on at least one side surface of the current collector is provided with grooved areas at at least a portion of the corner regions. The grooving area is provided with multiple grooves, which are spaced apart along the width direction of the first electrode and each groove extends along the length direction of the first electrode.

2. The electrochemical device according to claim 1, characterized in that, Along the width direction of the first electrode, the grooved area overlaps with the central region of the first electrode.

3. The electrochemical device according to claim 2, characterized in that, Each of the scribing areas includes multiple sub-scribing areas, which are sequentially distributed along the width direction of the first electrode sheet; The plurality of sub-slot regions include a first sub-slot region, which overlaps with the central region of the first electrode sheet, and along the width direction of the first electrode sheet, the groove spacing of the grooves in the first sub-slot region is smaller than the groove spacing of the grooves in the other sub-slot regions.

4. The electrochemical device according to claim 3, characterized in that, The plurality of sub-slot regions further include a second sub-slot region and a third sub-slot region, wherein the second sub-slot region, the first sub-slot region and the third sub-slot region are distributed sequentially along the width direction of the first electrode sheet; Along the width direction of the first electrode, the groove spacing of the groove in the first sub-groove area is L1, the groove spacing of the groove in the second sub-groove area is L2, and the groove spacing of the groove in the third sub-groove area is L3. L1, L2, and L3 satisfy: L2>L1 and L1<L3.

5. The electrochemical device according to claim 4, characterized in that, The L1, L2, and L3 satisfy the following conditions: 0.2mm≤L1≤0.8mm, 1mm≤L2≤2mm, and 1mm≤L3≤2mm.

6. The electrochemical device according to claim 4, characterized in that, The width of the first electrode is A; Along the width direction of the first electrode, the width of the first sub-slot area is B1, the width of the second sub-slot area is B2, and the width of the third sub-slot area is B3. B1, B2, and B3 satisfy: 0.3A≤B1≤0.8A, 0.1A≤B2≤0.3A, and 0.1A≤B3≤0.3A.

7. The electrochemical device according to claim 3, characterized in that, Along the width direction of the first electrode, there is a spacing M between two adjacent sub-slot regions, wherein M satisfies: 0.2mm≤M≤1mm.

8. The electrochemical device according to any one of claims 2 to 7, characterized in that, The active material layer on at least one side surface of the current collector is provided with a receiving groove, which is used to expose a portion of the surface of the current collector. The receiving groove is located between any two adjacent scribing areas, and extends from one side edge of the first electrode sheet toward the central region of the first electrode sheet along the width direction of the first electrode sheet.

9. The electrochemical device according to claim 8, characterized in that, Along the winding direction of the first electrode, one end of the first electrode is the winding start end located in the inner circle of the electrode assembly, and the other end is the winding end located in the outer circle of the electrode assembly. The receiving groove is provided with a grooving area at one of the K1 consecutive corner areas facing the winding start end, and the receiving groove is provided with a grooving area at one of the K2 consecutive corner areas facing the winding end end. The first electrode has N layers; when N is an even number, N, K1, and K2 satisfy: 1≤K1≤0.5*N-1, 1≤K2≤0.5*N-1; when N is an odd number, N, K1, and K2 satisfy: 1≤K1≤0.5*(N-1), 1≤K2≤0.5*(N-1).

10. The electrochemical device according to claim 1, characterized in that, In the width direction of the first electrode, there is a first distance E1 between one edge of the active material layer and the groove closest to it, and a second distance E2 between the other edge of the active material layer and the groove closest to it. E1 and E2 satisfy: 0≤E1≤3mm, 0≤E2≤3mm.

11. The electrochemical device according to claim 1, characterized in that, Along the width direction of the first electrode, the groove width is X, where X satisfies: 20μm≤X≤80μm; and / or, Along the length of the first electrode, the length of the groove is W, where W satisfies: 5mm ≤ W ≤ 20mm; and / or, The sum of the areas of the plurality of grooves in any of the grooved areas is S1, and the area of ​​the corner area corresponding to the grooved area is S2. S1 and S2 satisfy: 0.4% ≤ S1 / S2 ≤ 8%.

12. The electrochemical device according to claim 1, characterized in that, The thickness of the active material layer is H2; The groove depth is H1, and H1 satisfies: 0.3H2≤H1≤0.7H2, and / or, H2 satisfies: 20μm≤H2≤200μm.

13. The electrochemical device according to claim 1, characterized in that, The groove is formed by a plurality of continuously arranged and interconnected micropores, the projection of which onto the thickness of the active material layer is circular, elliptical, fan-shaped or polygonal.

14. The electrochemical device according to claim 13, characterized in that, The pore size of the micropore is D, and D satisfies: 5μm≤D≤20μm.

15. An electronic device, characterized in that, Includes the electrochemical device as described in any one of claims 1 to 14.

Images