Electrode assembly, energy storage apparatus and electric device

Abstract

The present application relates to the technical field of energy storage. Disclosed are an electrode assembly, an energy storage apparatus and an electric device. The electrode assembly (30) comprises a spreading-flat region (34), a first bending region (35), and a second bending region (36), wherein a first electrode sheet (31) comprises a first starting section (311) and a plurality of first spreading-flat layers (312) located in the spreading-flat region (34); and a second electrode sheet (32) comprises a second starting section (321), a second spreading-flat layer (322), and a plurality of third spreading-flat layers (323) located in the spreading-flat region (34), the second spreading-flat layer (322) being located between the second starting section (321) and the first starting section (311); the distance between a second electrode sheet starting end (329) and the first bending region (35) is not greater than a first reference distance, and the distance between a first electrode sheet starting end (317) and the second bending region (36) is not greater than a second reference distance. In the present application, by winding the second starting section (321) on the second electrode sheet (32) an extra half-turn, and arranging the first electrode sheet starting end (317) and the second electrode sheet starting end (329) adjacent to the first and second bending regions respectively, the gap between the first starting section (311) and the first spreading-flat layer (312) adjacent thereto in a winding direction is compensated for, thus reducing the bending curvature of the first electrode sheet (31) in the bending regions, preventing the formation of creases.

Description

Electrode assembly, energy storage device and electric equipment

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to Chinese Patent Application No. 202410804306.6, filed on June 20, 2024, entitled “Electrode assembly, energy storage device and electric equipment”, the entire contents of which are incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of energy storage, in particular to an electrode assembly, an energy storage device and an electric equipment. BACKGROUND

[0004] A secondary battery, also known as a rechargeable battery or a storage battery, refers to a battery that can be activated by charging after discharging and continue to be used. The recyclable nature of the secondary battery makes it gradually become the main power source of electric equipment. As the demand for secondary batteries gradually increases, people's requirements for its performance in all aspects are also getting higher and higher, especially for the service life.

[0005] In the related art, a secondary battery is usually composed of a battery top cover, an electrode assembly and a shell. The electrode assembly includes a positive electrode sheet and a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet and the separator are wound to form the electrode assembly. After the lamination of the positive electrode sheet, the negative electrode sheet and the separator is completed, heat pressing is needed, which can easily cause the positive electrode sheet in the innermost layer of the bending area to produce a crease due to small curvature, and even break, thereby affecting the capacity of the secondary battery, and at the same time, the separator is pierced to cause short circuit of the positive electrode sheet and the negative electrode sheet, thereby affecting the yield of the secondary battery. SUMMARY

[0006] One main purpose of the present application is to provide an electrode assembly, an energy storage device and an electric equipment capable of ensuring capacity.

[0007] To achieve the above purpose, the present application adopts the following technical solutions:

[0008] According to an aspect of the present application, an electrode assembly is provided, comprising a first electrode tab, a second electrode tab and a separator, and the electrode assembly is a winding structure after the first electrode tab, the separator and the second electrode tab are laminated and wound; the electrode assembly comprises a flat area, and a first bending area and a second bending area located at two ends of the flat area; the first electrode tab comprises a first starting section and a plurality of first flat layers located in the flat area; the second electrode tab comprises a second starting section, a second flat layer and a plurality of third flat layers located in the flat area; the first starting section and the second starting section have an overlapping area in a thickness direction of the electrode assembly; the second flat layer is located between the first starting section and the second starting section; the plurality of third flat layers and the plurality of first flat layers are distributed on a side of the second starting section and the first starting section away from a winding center; the second electrode tab starting end faces the first bending area, and a distance between the second electrode tab starting end and the first bending area is less than or equal to a first reference distance; and the first electrode tab starting end faces the second bending area, and a distance between the first electrode tab starting end and the second bending area is less than or equal to a second reference distance.

[0009] In the present application, the second starting section of the second electrode tab with multiple winding turns compensates for the gap between the first starting section of the first electrode tab and the first flat layer (starting flat layer) adjacent in the winding direction in the thickness direction of the electrode assembly, reduces the bending curvature of the first electrode tab in the bending area, avoids the occurrence of creases, and thus guarantees the integrity of the first electrode tab and the yield and capacity of the energy storage device with the electrode assembly. In addition, the second electrode tab starting end is arranged close to the first bending area, and the first electrode tab starting end is arranged close to the second bending area, so as to compensate for the gap between the first starting section of the first electrode tab and the starting flat layer at positions close to the first bending area and the second bending area, thereby further reducing the bending curvature of the first electrode tab in the first bending area and the second bending area, reducing the occurrence of creases of the first electrode tab, and thus guaranteeing the integrity of the first electrode tab.

[0010] According to an aspect of the present application, an energy storage device is provided, comprising:

[0011] A shell comprising a receiving cavity with an opening; a battery top cover sealing the opening of the receiving cavity; and the electrode assembly of the above aspect is accommodated in the receiving cavity.

[0012] According to an aspect of the present application, an electric device is provided, comprising the energy storage device of the above aspect, and the energy storage device supplies power to the electric device.

[0013] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0014] The above and other features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0015] FIG. 1 is a structural schematic diagram of a domestic energy storage system according to an exemplary embodiment.

[0016] FIG. 2 is an exploded structural schematic diagram of an energy storage device according to an exemplary embodiment.

[0017] FIG. 3 is a cross-sectional structural schematic diagram of an electrode assembly according to an exemplary embodiment.

[0018] FIG. 4 is a cross-sectional structural schematic diagram of an inner ring of the electrode assembly shown in FIG. 3.

[0019] FIG. 5 is a cross-sectional structural schematic diagram of an inner ring of another electrode assembly according to an exemplary embodiment.

[0020] FIG. 6 is a cross-sectional structural schematic diagram of an inner ring of yet another electrode assembly according to an exemplary embodiment.

[0021] FIG. 7 is a cross-sectional structural schematic diagram of an inner ring of still another electrode assembly according to an exemplary embodiment.

[0022] FIG. 8 is a cross-sectional structural schematic diagram of still another electrode assembly according to an exemplary embodiment.

[0023] FIG. 9 is a structural schematic diagram of an electrical device according to an exemplary embodiment.

[0024] In the drawings, reference numerals: 100, energy storage device; 200, electrical energy conversion device; 300, user load; 400, electrical device; 10, housing; 20, battery top cover; 30, electrode assembly; 11, accommodation cavity; 21, end cap; 22, electrode terminal; 23, liquid injection hole; 24, explosion-proof valve; 31, first tab; 32, second tab; 33, separator; 34, flat area; 35, first bending area; 36, second bending area; 311, first starting section; 312, first flat layer; 313, starting flat layer; 314, finishing flat layer; 315, first finishing section; 316, first tab lug; 317, first tab starting end; 321, second starting section; 322, second flat layer; 323, third flat layer; 324, metal foil material; 325, active coating layer; 326, bending section; 327, second tab lug; 328, second finishing section; 329, second tab starting end; 3211, coating area; 3212, thinning area; 331, separator starting section. DETAILED DESCRIPTION

[0025] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations can be implemented in any numerous ways, and example implementations should not be construed as limited to having been set forth in the description herein; rather, descriptions herein provide example implementations such that one skilled in the art will understand how to make and use an example implementation. Like reference numerals refer to like elements throughout the description of the figures; thus, description of some elements can be omitted in some of the figures.

[0026] Since the energy required by people has strong time and space, in order to reasonably use energy and improve utilization, it is necessary to store the energy in the form of one energy form or converted into another energy form through a medium or device, and then release it in a specific energy form based on future application.

[0027] At present, green energy mainly includes light energy, wind energy, etc., and light energy and wind energy have the problems of strong intermittency and large fluctuation, which will cause the voltage of green power grid to be unstable (not enough electricity at peak electricity consumption time, and too much electricity at low electricity consumption time), and unstable voltage will cause damage to electricity, Therefore, due to insufficient electricity demand or insufficient grid accommodation capacity, the problem of "abandoning wind and light" may be caused.

[0028] In order to solve the problem of insufficient electricity demand or insufficient grid accommodation capacity, it is necessary to rely on energy storage devices. That is, through energy storage devices, electrical energy is converted into other forms of energy through physical or chemical means for storage, and when needed, the energy stored in the energy storage device is converted into electrical energy for release. Simply put, the energy storage device is similar to a large "power bank", which stores electrical energy when light energy and wind energy are sufficient, and releases the stored electrical energy when needed.

[0029] The current energy storage (i.e. energy storage) application scenarios are relatively wide, including power generation side energy storage, power grid side energy storage, renewable energy grid-connected energy storage, and user side energy storage, etc. The corresponding types of energy storage devices include:

[0030] (1) Large energy storage containers applied in power grid side energy storage scenarios, which can be used as high-quality active and reactive power regulation power sources in the power grid, realize load matching of electrical energy in time and space, enhance renewable energy consumption capacity, and have great significance in power grid system backup, relieving peak load power supply pressure and peak regulation;

[0031] (2) Small and medium-sized energy storage cabinets applied in commercial energy storage scenarios (banks, shopping malls, etc.) at the user side and small household energy storage boxes applied in household energy storage scenarios at the user side, mainly operating in the mode of "peak load shifting". Due to the large price difference between the electricity prices at the peak and valley positions according to the electricity demand, after the user has the energy storage device, in order to reduce the cost, the energy storage device (energy storage cabinet / box) is usually charged at the low electricity price valley period; the electricity in the energy storage device is discharged for use at the high electricity price peak period, so as to achieve the purpose of saving electricity cost. In addition, in remote areas and areas with high incidence of natural disasters such as earthquakes and hurricanes, the existence of household energy storage devices is equivalent to that the user provides a standby power source for himself and the power grid, which eliminates the inconvenience caused by frequent power outages due to disasters or other reasons.

[0032] Taking the household energy storage scenario in the user-side energy storage as an example, FIG. 1 shows a household energy storage system, which includes an energy storage device 100 and an electric energy conversion device 200 (such as a photovoltaic panel), and a user load 300 (such as a street lamp, a household appliance, etc.), the energy storage device 100 is a small energy storage box, which can be installed on an outdoor wall in a wall-mounted manner. Specifically, the electric energy conversion device 200 can convert solar energy into electric energy at the low electricity price valley period, and store the electric energy through the energy storage device 100, and then supply the user load 300 for use at the high electricity price peak period, or supply the user load 300 for use when the power grid is disconnected / power off.

[0033] In combination with the above-mentioned energy storage by physical or electrochemical means, taking electrochemical energy storage as an example, the energy storage device 100 includes at least one chemical battery, which uses chemical elements in the chemical battery as an energy storage medium to realize the charging and discharging process through chemical reactions or changes of the energy storage medium. In simple terms, the electric energy generated by light energy and wind energy is stored in at least one group of chemical batteries through chemical reactions or changes of the energy storage medium, and then the electric quantity stored in the at least one group of chemical batteries is released for use through chemical reactions or changes of the energy storage medium when the use of external electric energy reaches the peak, or is transferred to a place where the electric quantity is in short supply for use.

[0034] The energy storage device 100 provided by the embodiments of the present application can be, but is not limited to, a single battery (secondary battery), and a battery module, a battery pack, a battery system, etc. composed of single batteries. For the single battery, it can be a lithium ion battery, a lithium-sulfur battery, a sodium lithium ion battery, a sodium ion battery, a magnesium ion battery, etc., and the single battery can be in the form of a flat body, a cuboid, etc., which is not limited in the embodiments of the present application.

[0035] Next, taking the energy storage device 100 as a square single battery as an example, the energy storage device 100 is explained in detail.

[0036] FIG. 2 illustrates an exploded structural schematic diagram of an energy storage device 100 according to an embodiment of the present application. As shown in FIG. 2, the energy storage device 100 includes a housing 10, a battery top cover 20, and an electrode assembly 30. The housing 10 includes a receiving cavity 11 having an opening. The electrode assembly 30 is accommodated in the receiving cavity 11. The battery top cover 20 seals the opening of the receiving cavity 11.

[0037] The housing 10 can be a cylindrical structure having one open end. In this case, the energy storage device 100 includes one battery top cover 20 to seal the opening of the housing 10. Alternatively, the housing 10 can be a cylindrical structure having two open ends. In this case, the energy storage device 100 includes one battery top cover 20 and one cover plate, or two battery top covers 20. The one battery top cover 20 and the one cover plate, or the two battery top covers 20 seal the two openings of the housing 10, respectively.

[0038] As shown in FIG. 2, the battery top cover 20 includes an end cover 21 and an electrode terminal 22. The electrode terminal 22 is disposed on the end cover 21 and connected to the electrode assembly 30 at one end and exposed outside the end cover 21 at the other end, thereby serving as an output terminal of the energy storage device 100.

[0039] Optionally, as shown in FIG. 2, the end cover 21 is provided with a pressure relief valve 24 and a liquid injection hole 23. The liquid injection hole 23 is used to inject electrolyte into the receiving cavity 11 of the energy storage device 100. The pressure relief valve 24 is used to discharge the gas generated in the receiving cavity of the housing 10, thereby improving the safety of the energy storage device 100.

[0040] The electrode assembly 30 includes a first electrode sheet 31, a second electrode sheet 32, and a separator 33 stacked together. The separator 33 is located between the first electrode sheet 31 and the second electrode sheet 32. The first electrode sheet 31 and the second electrode sheet 32 each have a tab at an end in the axial direction of the electrode assembly 30, thereby forming a first tab 316 and a second tab 327 of the electrode assembly 30. The first tab 316 and the second tab 327 can be located at the same end of the electrode assembly 30 as shown in FIG. 2, or can be located at different ends of the electrode assembly 30. Taking the case where the first tab 316 and the second tab 327 are located at the same end of the electrode assembly 30 as an example, the first tab 316 and the second tab 327 are connected to the first electrode terminal and the second electrode terminal of the battery top cover 20, respectively, so as to realize the output of the electric energy of the electrode assembly 30 through the first electrode terminal and the second electrode terminal.

[0041] It should be noted that the energy storage device 100 further includes a metal adapter. The metal adapter is used to connect the tabs of the electrode assembly 30 to the electrode terminal 22 of the battery top cover 20.

[0042] In the related art, for the prepared energy storage device 100, it is found in the quality inspection process that the capacity of part of the energy storage device 100 decays and deviates from the preset capacity. In this regard, the inventors disassemble the energy storage device 100 with capacity decay and conduct careful research and find that a fold appears at the innermost position of the first tab 31 in the bending area of the electrode assembly 30, and even the first tab 31 is broken, which causes the active coating at the position of the first tab 31 to fall off, and further causes the capacity of the energy storage device 100 to decay.

[0043] In this regard, based on the structural adjustment of the electrode assembly 30 by the inventors, the energy storage device 100 provided in the embodiments of the present application and the electrode assembly 30 included in the energy storage device 100 are provided. After analyzing the actual products of the energy storage device 100, it is found that the capacity of the energy storage device 100 is effectively improved, thereby improving the product yield of the energy storage device 100.

[0044] In the embodiments of the present application, as shown in FIG. 3, the electrode assembly 30 includes the first tab 31, the second tab 32, and the separator 33 between the first tab 31 and the second tab 32. The winding structure of the first tab 31, the second tab 32, and the separator 33 after being stacked and wound in the winding direction O is the electrode assembly 30.

[0045] The electrode assembly 30 can be a structure after the winding structure is heat pressed. The first tab 31 and the second tab 32 each include a metal foil 324 and an active coating coated on both sides of the metal foil 324, and the difference lies in that the active coatings included in the first tab 31 and the second tab 32 are set according to the different polarities of the first tab 31 and the second tab 32. For example, the first tab 31 is a positive tab, and the second tab 32 is a negative tab. At this time, the active coating on the first tab 31 includes a lithium ion coating, and the active coating on the second tab 32 is a graphite coating. In addition, the metal foils 324 included in the first tab 31 and the second tab 32 can also be different. For example, the first tab 31 is a positive tab, and the second tab 32 is a negative tab. At this time, the metal foil 324 included in the first tab 31 is a metal aluminum foil, and the metal foil 324 included in the second tab 32 is a metal copper foil.

[0046] The second tab starting end 329 extends out of the first tab starting end 317, and the second tab ending end extends out of the first tab ending end. In the axial direction of the electrode assembly 30, the edge of the second tab 32 is at least flush with the edge of the first tab 31, so as to ensure that the lithium ions released by the first tab 31 can be completely accepted by the second tab 32 in the charging and discharging stage of the electrode assembly 30, so as to avoid the situation of lithium precipitation, and the lithium ions released by the first tab 31 form crystals and pierce the separator 33.

[0047] Optionally, the size of the second tab starting end 329 extending out of the first tab starting end 317 (the length of the second tab starting end 329 extending out flattened) and the size of the second tab ending end extending out of the first tab ending end (the length of the second tab ending end extending out flattened) are both greater than or equal to 3.5 mm; in the axial direction of the electrode assembly 30, the size of the edges of the second tab 32 extending out of the edges of the first tab 31 are all greater than or equal to 0.5 mm. For example, the size of the second tab starting end 329 extending out of the first tab starting end 317 and the size of the second tab ending end extending out of the first tab ending end are all 3.5 mm, 3.7 mm, 4.0 mm, 4.5 mm, 5 mm, etc.; for example, the size of the edges of the second tab 32 extending out of the edges of the first tab 31 are all 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, etc.

[0048] In this way, it can be ensured that the lithium ions released by the first tab 31 can be completely accepted by the second tab 32, while avoiding the second tab starting end 329 and the second tab ending end extending out too much, affecting the capacity of the electrode assembly 30, and avoiding the edges of the second tab 32 extending out too much, increasing the axial size of the electrode assembly 30.

[0049] The size of the second tab starting end 329 extending out of the first tab starting end 317 and the size of the second tab ending end extending out of the first tab ending end can be the same or different, and in the axial direction of the electrode assembly 30, the size of the edges of the second tab 32 extending out of the edges of the first tab 31 on both sides can be the same or different, which is not limited by the embodiments of the present application.

[0050] In the embodiments of the present application, as shown in FIG. 3, the electrode assembly 30 includes a flat area 34 and first and second bending areas 35 and 36 located at both ends of the flat area 34, i.e., the first bending area 35, the flat area 34, and the second bending area 36 are distributed along the width direction W of the electrode assembly 30.

[0051] The first tab 31 includes a first starting section 311 and a plurality of first flat layers 312 located in the flat area 34, and the second tab 32 includes a second starting section 321, a second flat layer 322, and a plurality of third flat layers 323 located in the flat area 34. The first starting section 311 and the second starting section 321 have an overlapping area in the thickness direction H of the electrode assembly 30, the second flat layer 322 is located between the second starting section 321 and the first starting section 311, and the plurality of third flat layers 323 and the plurality of first flat layers 312 are both located on the side of the second starting section 321 and the first starting section 311 away from the winding center.

[0052] Therefore, for the first starting section 311 included in the first tab 31, and the starting tiling section 313 included in the plurality of first tiling sections 312 and adjacent to the first starting section 311 in the winding direction O, the second starting section 321 with multiple winding turns on the second tab 32 is arranged to compensate for the gap between the first starting section 311 and the starting tiling section 313 in the thickness direction H of the electrode assembly 30, and to reduce the bending curvature of the first tab 31 in the first bending area 35 and the second bending area 36 of the electrode assembly 30 after hot pressing, so as to reduce the occurrence of creases on the first tab 31, and further reduce the active coating falling off the first tab 31, thereby ensuring the integrity of the first tab 31 and the yield and capacity of the energy storage device 100 with the electrode assembly 30.

[0053] In some embodiments, in combination with the above-mentioned separator 33, as shown in FIG. 4, the separator 33 includes a separator starting section 331 between the second starting section 321 and the second tiling section 322, and the number of winding turns of the separator starting section 331 is greater than or equal to 1.25 and less than or equal to 3. For example, the number of winding turns of the separator starting section 331 is 1.5, 2, 2.5, 3, etc. As shown in FIG. 4, the number of winding turns of the separator starting section 331 is 2 turns.

[0054] Therefore, by arranging the separator starting section 331, the gap between the first starting section 311 and the starting tiling section 313 on the first tab 31 in the thickness direction H of the electrode assembly 30 is compensated, and the bending curvature of the first tab 31 at the innermost layer of the first bending area 35 and the second bending area 36 of the electrode assembly 30 after hot pressing is reduced, so as to reduce the occurrence of creases on the first tab 31.

[0055] In some embodiments, as shown in FIG. 3 or FIG. 4, the second tab starting end 329 is towards the first bending area 35, and the distance d1 between the second tab starting end 329 and the first bending area 35 is less than or equal to a first reference distance, and the first tab starting end 317 is towards the second bending area 36, and the distance d2 between the first tab starting end 317 and the second bending area 36 is less than or equal to a second reference distance.

[0056] Therefore, by arranging the second tab starting end 329 close to the first bending area 35 and the first tab starting end 317 close to the second bending area 36, the gap between the first starting section 311 and the starting tiling section 313 on the first tab 31 at the positions close to the first bending area 35 and the second bending area 36 is compensated, and the bending curvature of the first tab 31 at the innermost layer of the first bending area 35 and the second bending area 36 of the electrode assembly 30 after hot pressing is further reduced, so as to reduce the occurrence of creases on the first tab 31, and further reduce the active coating falling off the first tab 31, thereby ensuring the capacity of the electrode assembly 30.

[0057] The distance d1 between the second tab starting end 329 and the first bending area 35 mainly depends on the process error when winding the second tab 32. For example, when the first reference distance is 5 mm, the distance between the second tab starting end 329 and the first bending area 35 is 0 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm. Further, the distance between the second tab starting end 329 and the first bending area 35 can be less than or equal to 3 mm.

[0058] The distance d2 between the first tab starting end 317 and the second bending area 36 mainly depends on the process error when winding the first tab 31, or the process error when winding the first tab 31 and the active coating 325 on the second starting section 321.

[0059] In some embodiments, the second starting section 321 includes a single-sided coated active coating 325 as shown in FIG. 5, or a double-sided coated active coating 325 as shown in FIG. 4.

[0060] In this way, the electrolyte is stored by the double-sided or single-sided coated active coating 325 on the second starting section 321, so that the consumed electrolyte on the second and third flat layers 322 and 323 adjacent to the second starting section 321 can be replenished during the charging and discharging of the electrode assembly 30, so as to ensure the migration of lithium ions and the cycle performance of the electrode assembly 30.

[0061] Of course, the second starting section 321 can also be a structure in which both sides are coated with the active coating 325, which facilitates reducing the loss of the active coating 325 and reducing the weight of the electrode assembly 30, thereby facilitating lightweight.

[0062] When the single-sided or double-sided coated active coating 325 is fully coated, the second starting section 321 is designed as a whole with equal thickness, so that the first tab starting end 317 can be designed to be closer to the second bending area 36. At this time, the distance between the first tab starting end 317 and the second bending area 36 mainly depends on the process error when winding the first tab 31, so that the distance d2 between the first tab starting end 317 and the second bending area 36 can be further set to be less than or equal to a third reference distance (less than the second reference distance). For example, when the third reference distance is 5 mm, the distance between the first tab starting end 317 and the second bending area 36 is 0 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm. Further, the distance between the first tab starting end 317 and the second bending area 36 can be less than or equal to 3 mm.

[0063] For the case that the second starting section 321 includes the double-sided coated active coating layer 325 as shown in FIG. 4, the entire second tab 32 includes the double-sided coated active coating layer 325 from the starting end to the ending end, so as to ensure that the active coating layer 325 on the second tab 32 extends out of the first tab starting end 317 by a distance greater than 3.5 mm.

[0064] For the case that the second starting section 321 includes the active coating layer 325 on the outer side (i.e. the side away from the winding center), the outer side of the entire second tab 32 includes the active coating layer 325 from the starting end to the ending end, so as to ensure that the active coating layer 325 on the outer side of the second tab 32 extends out of the first tab starting end 317 by a distance greater than 3.5 mm.

[0065] For the case that the second starting section 321 includes the active coating layer 325 on the inner side (i.e. the side close to the winding center) as shown in FIG. 5, the second tab 32 includes a bending section 326 at the second bending area 36; the bending section 326 is connected to the second starting section 321 and the second flat layer 322 respectively, and the bending section 326 includes the active coating layer 325 on the side away from the winding center. At this time, the outer side of the entire second tab 32 includes the active coating layer 325 from the bending section 326 to the ending end, and the length of the active coating layer 325 on the outer side of the bending section 326 extending out of the first tab starting end 317 is greater than or equal to 3.5 mm, so as to ensure that the active coating layer 325 on the outer side of the second tab 32 extends out of the first tab starting end 317 by a distance greater than or equal to 3.5 mm.

[0066] It should be noted that for the case that the second starting section 321 includes the single-sided coated active coating layer 325, the overall thickness of the electrode assembly 30 can be reduced, so as to reduce the group margin of the electrode assembly 30 in the thickness direction, to avoid the case that the electrode assembly 30 is pressed against the inner wall of the shell 10. In addition, in addition to the above-mentioned cases of the double-sided coated active coating layer 325 and the single-sided coated active coating layer 325, the second starting section 321 can also be a blank foil area, and at this time the active coating layer 325 on the second tab 32 can refer to the case that the second tab 32 includes the bending section 326 at the second bending area 36, and the bending section 326 includes the active coating layer 325 coated on the outer side, and the present application embodiment will not be described here.

[0067] In other embodiments as shown in FIG. 6 or FIG. 7, the second starting section 321 includes a coated area 3211 and a thinned area 3212, and the coated area 3211 is located between the thinned area 3212 and the second bending area 36; at this time, the first tab 31 can be arranged such that the first starting section 311 and the coated area 3211 do not have an overlapping area in the thickness direction H of the electrode assembly 30.

[0068] The thickness of the coating area 3211 on the second starting section 321 is greater than the thickness of the thinning area 3212, so that the overall thickness of the electrode assembly 30 can be reduced by the arrangement of the thinning area 3212, thereby reducing the group margin of the electrode assembly 30 in the thickness direction to avoid the situation that the electrode assembly 30 is pressed in the thickness direction of the electrode assembly 30 by the inner wall of the shell 10. The arrangement of the coating area 3211 can compensate for the gap between the first starting section 311 and the starting flat layer 313 in the thickness direction H of the electrode assembly 30 near the second bending area 36, thereby reducing the bending curvature of the first pole piece 31 of the motor assembly at the innermost layer of the second bending area 36. The matching of the thinning area 3212 and the first starting section 311 can also reduce the gap between the first starting section 311 and the starting flat layer 313 at the positions near the first bending area 35 and the second bending area 36, thereby reducing the bending curvature of the first pole piece 31 of the electrode assembly 30 at the innermost layer of the first bending area 35 and the second bending area 36.

[0069] For the case that the second starting section 321 includes the coating area 3211 and the thinning area 3212, the distance d2 between the first pole piece starting end 317 and the second bending area 36 mainly depends on the process error when winding the first pole piece 31 and the width (i.e., the size in the width direction W of the electrode assembly 30) of the coating area 3211 on the second starting section 321, that is, the distance d2 between the first pole piece starting end 317 and the second bending area 36 is less than or equal to the first reference distance (greater than the third reference distance). For example, when the first reference distance is 10 mm, the distance d2 between the first pole piece starting end 317 and the second bending area 36 is 2 mm, 4 mm, 6 mm, 8 mm, or 10 mm. Further, the distance d2 between the first pole piece starting end 317 and the second bending area 36 can be less than or equal to 6 mm.

[0070] For example, the width of the coating area 3211 on the second starting section 321 is 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm.

[0071] Optionally, the coating area 3211 of the second starting section 321 includes a double-sided active coating layer 325, the thinning area 3212 is a hollow foil structure (i.e., the second pole piece 32 of the thinning area 3212 only includes a metal foil 324), or as shown in FIG. 6, the coating area 3211 of the second starting section 321 includes a double-sided active coating layer 325, and the thinning area 3212 includes a single-sided active coating layer 325; or as shown in FIG. 7, the coating area 3211 of the second starting section 321 includes a single-sided active coating layer 325, and the thinning area 3212 is a hollow foil structure.

[0072] Thus, by setting at least one active coating layer on the coating area, the effect of storing electrolyte can be achieved, so as to replenish the electrolyte consumed on the adjacent second and third planar layers and ensure the cycle performance of the electrode assembly.

[0073] In the case where the thinning region 3212 includes a single-sided applied active coating 325, the active coating 325 can be located on the outer side or the inner side of the second electrode 32. Preferably, as shown in FIG6, the active coating 325 of the thinning region 3212 is located on the inner side of the second electrode 32 to ensure that the surface of the second starting segment 321 facing the first starting segment 311 is planar, thereby facilitating better support for the first starting segment 311 during hot-pressing and winding.

[0074] In the case where the coating area 3211 includes a single-sided active coating 325, the explanation of the entire second starting segment 321 including a single-sided active coating 325 can be referred to above, and the embodiments of this application will not be repeated here.

[0075] In some embodiments, the first electrode 31 includes a first terminal section 315, and the second electrode 32 includes a second terminal section 328; in the winding direction of the electrode assembly 30, the terminal end of the second terminal section 328 extends beyond the terminal end of the first terminal section 315, and the second terminal section 328 is located in a first bending region 35 or a second bending region 36. For example, as shown in FIG3 or FIG8, the second terminal section 328 is located in the second bending region 36.

[0076] This avoids the end of the second electrode 32 extending into the flattened area 34, reducing the thickness of the electrode assembly 30 and thus reducing the thickness margin of the electrode assembly 30. This prevents the electrode assembly 30 from being squeezed against the inner wall of the housing 10 in the thickness direction, which could cause the electrolyte to be squeezed out of each of the first flattened layers 312, the second flattened layer 322, and the third flattened layer 323. This ensures the electrolyte wetting effect of the first electrode 31 and the second electrode 32, thereby avoiding excessive current density and the occurrence of purple spots or lithium plating.

[0077] Optionally, one of the multiple third ply layers 323 of the second electrode 32 may be connected to the second termination section 328. In this case, as shown in FIG8, the second termination section 328 and the third ply layer 323 connected to the second termination section 328 may be located on the same side of the symmetry line C of the second bending region 36. In this way, the group margin of the electrode assembly 30 in the thickness direction can be reduced, as well as the group margin of the electrode assembly 30 in the width direction, so as to avoid the compression of the electrode assembly 30 with the inner wall of the housing 10 in the width and thickness directions after the electrode assembly 30 is inserted into the housing, and to avoid the occurrence of purple spots or lithium plating on the electrode assembly 30.

[0078] In some embodiments, the first tail section 315 and the second tail section 328 are located in the same bending area; for example, as shown in FIG. 3 or FIG. 8, the first tail section 315 included in the first tab 31 and the second tail section 328 included in the second tab 32 are both located in the second bending area 36.

[0079] Optionally, as shown in FIG. 8, the first tail section 315 and the tail layer 314 included in the plurality of first layers 312 of the first tab 31 are both located on the same side of the symmetry line C of the second bending area 36.

[0080] In some embodiments, the second tail section 328 is located outside the first tail section 315 to ensure that the lithium ions released by the first tail section 315 can be accepted by the second tail section 328. The first tail section 315 of the first tab 31 is arranged in the first bending area 35 or the second bending area 36, and the tail end of the first tab 31 does not exceed the widest position on the electrode assembly 30, thereby reducing the width of the electrode assembly 30 while increasing the capacity of the electrode assembly 30, reducing the group margin of the electrode assembly 30 in the width direction, and avoiding the electrode assembly 30 from being squeezed in the width direction by the inner wall of the shell 10, thereby avoiding the risk of S-shaped deformation of the electrode assembly 30.

[0081] In some embodiments, the second tail section 328 of the second tab 32 and the first tail section 315 of the first tab 31 both include a double-sided active coating. In this way, the active coating 325 on the second tab 32 extends beyond the active coating on the first tab 31, thereby ensuring that the lithium ions released by the first tail section 315 of the first tab 31 can be completely accepted by the second tail section 328 of the second tab 32, and avoiding the electrode assembly 30 from lithium precipitation. Of course, for the second tail section 328 included in the second tab 32, the inside of the second tail section 328 can also have an active coating 325 to ensure that the lithium ions released by the first tail section 315 can be completely accepted by the second tail section 328, and the embodiments of the present application do not limit this.

[0082] In the embodiments of the present application, at one end of the electrode assembly 30 in the axial direction, the first tab 31 and the second tab 32 are respectively provided with the first tab 316 and the second tab 327 to facilitate electrical connection with the first electrode terminal and the second electrode terminal through the first tab 316 and the second tab 327, respectively.

[0083] In some embodiments, as shown in FIG. 3 or FIG. 8, the second starting section 321, the second tiling layer 322, and at least one third tiling layer 323 of the plurality of third tiling layers 323 located on the side of the first starting section 311 close to the second starting section 321 all have the second tab 327.

[0084] In this way, by forming more second tabs 327 than the related art, the current density on the second tab 32 can be significantly reduced by the larger number of second tabs 327, so that the transmission rate of electrons and the transmission rate of ions reach a dynamic balance, reducing the generation of electrochemical polarization; in addition, after the second tab 327 is electrically connected to the electrode terminal 22 of the battery top cover 20, the current impedance can be reduced by the larger number of second tabs 327, thereby reducing the heating power at the connection between the second tab 327 and the electrode terminal 22.

[0085] The embodiments of the present application also provide a power consuming device 400, as shown in FIG. 9, which comprises the energy storage device 100 described in the above embodiments, and the energy storage device 100 supplies power to the power consuming device 400. In this way, in combination with the above description, the power consuming device 400 of the present application can ensure the stability of the power consuming device 400 during use, avoiding the situation that the power consuming device 400 stops working due to the capacity attenuation of the energy storage device 100.

[0086] In the embodiments of the present application, the terms "first", "second", "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance; the term "multiple" refers to two or more, unless otherwise explicitly limited. The terms "mounting", "connecting", "connecting", "fixing" and the like should be broadly understood, for example, "connecting" can be fixed connection, or detachable connection, or integrally connected; "connected" can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0087] In the description of the embodiments of the present application, it should be understood that the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used for the purpose of facilitating the description of the embodiments of the present application and simplifying the description, and do not indicate or imply that the devices or units referred to must have a particular direction, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the embodiments of the present application.

[0088] In the description of the application, the terms "one embodiment", "some embodiments", "certain embodiments", etc. mean that the particular feature, structure, material or characteristic following the term is included in at least one embodiment of the application. The illustrative examples of the application should not be construed as being limiting. Further, the described specific features, structures, materials or characteristics can be combined in any suitable manner in one or more embodiments or examples of the application.

[0089] The above merely provides preferred embodiments of the application, and is not intended to limit the application. The application can be modified and changed in various ways by those skilled in the art, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. An electrode assembly, characterized by, The electrode assembly (30) comprises a first tab (31), a second tab (32) and a separator (33), and the electrode assembly (30) has a jelly-roll structure after the first tab (31), the separator (33) and the second tab (32) are laminated and rolled; The electrode assembly (30) comprises a flat area (34), a first bending area (35) and a second bending area (36) located at both ends of the flat area (34), the first tab (31) comprises a first starting section (311) and a plurality of first flat layers (312) located in the flat area (34), and the second tab (32) comprises a second starting section (321), a second flat layer (322) and a plurality of third flat layers (323) located in the flat area (34); The first starting section (311) and the second starting section (321) have an overlapping area in the thickness direction (H) of the electrode assembly (30), the second flat layer (322) is located between the first starting section (311) and the second starting section (321), and a plurality of the third flat layers (323) and a plurality of the first flat layers (312) are distributed on the side of the second starting section (321) and the first starting section (311) away from the rolling center. The second tab starting end (329) faces the first bending area (35), and the distance between the second tab starting end (329) and the first bending area (35) is less than or equal to a first reference distance, and the first tab starting end (317) faces the second bending area (36), and the distance between the first tab starting end (317) and the second bending area (36) is less than or equal to a second reference distance.

2. The electrode assembly of claim 1, wherein, The second starting section (321) comprises a single-sided active coating (325) or a double-sided active coating (325), the distance between the first tab starting end (317) and the second bending area (36) is less than or equal to a third reference distance, and the third reference distance is less than the second reference distance.

3. The electrode assembly of claim 2, wherein, The second starting section (321) comprises an active coating (325) located on the side away from the rolling center.

4. The electrode assembly of claim 2, wherein, The second starting section (321) comprises an active coating (325) located on the side close to the rolling center, and the second tab (32) comprises a bending section (326) located in the second bending area (36); The bending section (326) is connected to the second starting section (321) and the second flat layer (322) respectively, the bending section (326) comprises an active coating (325) located on the side away from the rolling center, and the size of the active coating (325) on the bending section (326) extending out of the first tab starting end (317) is greater than or equal to 3.5 mm.

5. The electrode assembly of claim 1, wherein, The second starting section (321) comprises a coating area (3211) and a thinning area (3212), and the coating area (3211) is located between the thinning area (3212) and the second bending area (36); The first starting section (311) and the coating area (3211) do not have an overlapping area in the thickness direction (H) of the electrode assembly (30).

6. The electrode assembly of claim 5, wherein, The coating area (3211) comprises a double-sided active coating (325), and the thinning area (3212) is a blank foil area or comprises a single-sided active coating (325).

7. The electrode assembly of claim 1, wherein, The first tab (31) comprises a first tail section (315), and the second tab (32) comprises a second tail section (328). In a winding direction of the electrode assembly (30), a tail end of the second tail section (328) protrudes beyond a tail end of the first tail section (315), and the second tail section (328) is located at the first bending area (35) or the second bending area (36).

8. The electrode assembly of claim 7, wherein, The plurality of first lay-up layers (312) comprises a tail lay-up layer (314) connected to the first tail section (315), and the first tail section (315) and the tail lay-up layer (314) are located on the same side of the symmetry line (C) of the second bending area (36).

9. An electrode assembly as claimed in any one of claims 1 to 8, wherein The size by which the tail end of the second tab (32) protrudes beyond the tail end of the first tab (31) is greater than or equal to 3.5 mm.

10. An electrode assembly as claimed in any one of claims 1 to 8, wherein The first tail section (315) of the first tab (31) and the second tail section (328) of the second tab (32) each comprise a double-sided active coating.

11. An electrode assembly as claimed in any one of claims 1 to 8, wherein The second starting section (321), the second lay-up layer (322), and at least one of the plurality of third lay-up layers (323) located on a side of the first starting section (311) close to the second starting section (321) each have a second tab (327).

12. An electrode assembly as claimed in any one of claims 1 to 8, wherein The separator (33) comprises a separator starting section (331) located between the second starting section (321) and the second lay-up layer (322), and the number of winding turns of the separator starting section (331) is greater than or equal to 1.25 and less than or equal to 3.

13. An energy storage device, characterized by, Comprise: A housing (10) comprising a receiving cavity (11) having an opening; A battery top cover (20) sealing the opening of the receiving cavity (11); The electrode assembly (30) of any one of claims 1-12 is accommodated in the receiving cavity (11).

14. An electrical device, characterized by The electric device (400) comprises the energy storage device (100) of claim 13, and the energy storage device (100) supplies power to the electric device (400). The electric device (400) comprises the energy storage device (100) of claim 13, and the energy storage device (100) supplies power to the electric device (400).

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