Electrochemical device and electronic equipment

Abstract

The utility model relates to electrochemistry energy storage technical field discloses a kind of electrochemical device and electronic equipment, electrochemical device includes electrode assembly, electrode assembly includes positive sheet, negative sheet and diaphragm between positive sheet and negative sheet, positive sheet, diaphragm and negative sheet are stacked and wound arrangement;Positive sheet includes positive current collector and the positive coating of coating on the surface of positive current collector, and negative sheet includes negative current collector and the negative coating of coating on the surface of negative current collector;Electrode assembly has straight area and corner area, and positive coating is provided with thinning groove in corner area, to improve the problem of lithium precipitation and stress concentration in corner area.

Description

Technical Field

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

[0002] With the continuous development of the field of electrochemical energy storage, people have increasingly higher requirements for electrochemical devices.

[0003] In the existing technology, the problem of lithium plating in the corner area of ​​wound cells is very common. On the one hand, it is caused by the low CB value (i.e., the ratio of the capacity of the negative electrode active material to the capacity of the positive electrode active material) in the corner area, which leads to lithium plating in the corner area. On the other hand, the stress concentration caused by the bending of the electrode in the corner area will accelerate the problem of lithium plating in the corner area. Utility Model Content

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an electrochemical device that can improve the problems of lithium deposition and stress concentration in corner areas.

[0005] This invention also proposes an electronic device having the above-mentioned electrochemical device.

[0006] An electrochemical device according to a first aspect of the present invention includes an electrode assembly, which includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode. The positive electrode, the separator, and the negative electrode are stacked and wound together. The positive electrode includes a positive current collector and a positive electrode coating coated on the surface of the positive current collector. The negative electrode includes a negative current collector and a negative electrode coating coated on the surface of the negative current collector. The electrode assembly has a flat region and a corner region, and the positive electrode coating has a thinning groove in the corner region.

[0007] The electrochemical device according to the embodiments of this utility model has at least the following beneficial effects: by stacking and winding the positive electrode, separator, and negative electrode, a wound core structure can be formed. By providing thinning grooves on the positive electrode coating in the corner region, the capacity of the positive electrode coating in the corner region can be reduced, the CB value in the corner region can be increased, and the problem of lithium plating in the corner region can be improved. In addition, the thinning grooves can also provide a gap between the positive electrode and the negative electrode to improve the problem of stress concentration in the corner region, further improving the problem of lithium plating in the corner region. Moreover, the thickness of the positive electrode coating in the area where the thinning grooves are not provided remains unchanged, and this area can play a supporting role, which helps to improve the problem of corner region collapse.

[0008] According to some embodiments of this utility model, the depth of the thinning groove is less than the thickness of the positive electrode coating.

[0009] According to some embodiments of the present invention, the thickness of the positive electrode coating is 30% ≤ the depth of the thinning groove is ≤ 50% of the thickness of the positive electrode coating.

[0010] According to some embodiments of the present invention, the positive current collector has a first surface disposed facing the center of the electrode assembly, the first surface is coated with a positive electrode coating, and the positive electrode coating coated on the first surface is provided with thinning grooves.

[0011] According to some embodiments of the present invention, the positive electrode sheet includes a plurality of straight segments and a plurality of bent segments alternately distributed along the winding direction; each straight segment is located in a straight region, and each bent segment is located in a corner region; the positive electrode coating located in the bent segment is provided with a thinning groove; wherein, 50% of the length of the bent segment along the winding direction is ≤ the maximum extension length of the thinning groove along the winding direction is ≤ 70% of the length of the bent segment along the winding direction; and / or, 70% of the width of the bent segment along the width direction is ≤ the maximum width of the thinning groove along the width direction is ≤ 80% of the width of the bent segment along the width direction, and the width direction is perpendicular to the winding direction.

[0012] According to some embodiments of the present invention, the positive electrode sheet includes multiple straight segments and multiple bent segments alternately distributed along the winding direction; each straight segment is located in a straight region, and each bent segment is located in a corner region; the positive electrode coating located in the bent segment is provided with a thinning groove, and the boundary between the thinning groove and the bent segment is spaced apart.

[0013] According to some embodiments of the present invention, the electrochemical device further includes adhesive paper covering the thinning groove.

[0014] According to some embodiments of this utility model, the difference between the length of the adhesive paper along the winding direction of the positive electrode sheet and the length of the thinning groove along the winding direction is ≤0.3mm.

[0015] According to some embodiments of this utility model, the difference between the width of the adhesive paper along the width direction of the positive electrode sheet and the width of the positive electrode sheet along the width direction is ≤0.4mm.

[0016] An electronic device according to a second aspect of the present invention includes the electrochemical device in any of the above embodiments.

[0017] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This diagram shows a partial cross-sectional view of the electrode assembly provided in an embodiment of the present invention. Figure 2 This diagram shows a partial structural schematic of the positive electrode sheet provided in the embodiment of the present invention in its unfolded state; Figure 3 This diagram shows a partial cross-sectional view of the positive electrode sheet located in the corner region in the unfolded state, according to an embodiment of the present invention. Figure 4 It shows Figure 2 A schematic diagram of the bent section of the neutral cathode plate.

[0019] Figure label: Electrode assembly 100; positive electrode 110; positive current collector 111; first surface 1111; second surface 1113; positive electrode coating 113; thinning groove 1131; straight section 115; bent section 117; negative electrode 130; negative current collector 131; negative electrode coating 133; separator 150; corner area 170; straight area 190; adhesive tape 300; winding direction X; width direction Y; thickness direction Z. Detailed Implementation

[0020] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0021] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0022] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0023] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0024] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0025] This application provides an electronic device, which includes an electrochemical device. The electronic device in this application is not particularly limited and can be any electronic device known in the prior art.

[0026] The electronic devices described in this application are not particularly limited in their application and can be used with any electronic device known in the prior art. These 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, robotic dogs, industrial robots, and android robots.

[0027] In some embodiments, the electrochemical device includes any device in which an electrochemical reaction occurs to interconvert chemical energy and electrical energy, and specific, non-limiting examples 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.

[0028] Please see Figures 1 to 3 In some embodiments, the electrochemical device includes a housing, an electrode assembly 100, and an electrolyte.

[0029] The housing can be a steel shell or a flexible shell. The electrode assembly 100 has a wound core structure and is disposed within the housing. Electrolyte can fill the housing to wet the electrode assembly 100.

[0030] The electrode assembly 100 includes a positive electrode 110, a negative electrode 130, and a separator 150 located between the positive electrode 110 and the negative electrode 130. The positive electrode 110, the separator 150, and the negative electrode 130 are stacked and wound together to form a wound core structure. For details, please refer to the prior art, which will not be repeated here.

[0031] The positive electrode 110 includes a positive current collector 111 and a positive electrode coating 113 coated on the surface of the positive current collector 111. The positive electrode coating 113 may be coated only on one surface of the positive current collector 111 along the thickness direction Z, or both opposite surfaces of the positive current collector 111 along the thickness direction Z may be coated with the positive electrode coating 113.

[0032] The negative electrode 130 includes a negative current collector 131 and a negative electrode coating 133 coated on the surface of the negative current collector 131. The negative electrode coating 133 may be coated only on one surface of the negative current collector 131 along the thickness direction Z, or both opposite surfaces of the negative current collector 131 along the thickness direction Z may be coated with the negative electrode coating 133.

[0033] The electrode assembly 100 has a flat region 190 and a corner region 170. The positive electrode coating 113 has a thinning groove 1131 in the corner region 170, which can reduce the capacity of the positive electrode coating 113 in the corner region 170 and increase the CB value of the corner region 170 (i.e., the ratio of the capacity of the negative electrode coating 133 to the capacity of the positive electrode coating 113), which helps to improve the problem of lithium plating in the corner region 170. In addition, the thinning groove 1131 can also provide a gap between the positive electrode sheet 110 and the negative electrode sheet 130 to improve the problem of stress concentration in the corner region 170, further improving the problem of lithium plating in the corner region 170. Furthermore, the thickness of the area of ​​the positive electrode coating 113 where the thinning groove 1131 is not provided remains unchanged, and this area can play a supporting role, which helps to improve the problem of collapse in the corner region 170.

[0034] It should be noted that the electrode assembly 100 has two corner areas 170, and the straight area 190 can be connected between the two corner areas 170. The structures of the two corner areas 170 are roughly the same. For ease of description, this application embodiment will use one of the corner areas 170 as an example for explanation.

[0035] The positive electrode coating 113 can be thinned by laser processing, embossing or other methods to form thinning grooves 1131.

[0036] The number of thinning grooves 1131 can be one or more, with "more" referring to two or more. For ease of description, the following explanation will focus on the case where there is only one thinning groove 1131.

[0037] The shape of the thinning groove 1131 can be selected in a variety of ways.

[0038] As an example, the shape of the thinning groove 1131 can be polygonal, circular, elliptical, semi-circular, or other shapes.

[0039] In some embodiments, the depth H of the thinning groove 1131 is less than the thickness of the positive electrode coating 113, thereby preventing the thinning groove 1131 from penetrating the positive electrode coating 113. The positive electrode sheet 110 can still have a continuous positive electrode coating 113 in the corner region 170. On the one hand, more positive electrode active material can be retained to ensure the capacitance of the electrochemical device. On the other hand, the mechanical strength of the positive electrode sheet 110 in the corner region 170 can be guaranteed, reducing the risk of the positive electrode sheet 110 breaking in the corner region 170.

[0040] As an example, the thinning groove 1131 may have a groove opening, a groove end wall, and a groove peripheral wall. The groove opening may be located on the surface of the positive electrode coating 113, the groove end wall may be spaced apart from the groove opening, and the groove peripheral wall may extend from the groove opening to the groove end wall. The groove end wall may be spaced apart from the surface of the positive electrode current collector 111. The groove opening of the thinning groove 1131 may be polygonal, circular, elliptical, semi-circular, or other shapes. The inner wall of the groove, formed by the groove peripheral wall and the groove end wall, may be U-shaped, V-shaped, or other shapes.

[0041] In some embodiments, 30% ≤ the thickness of the positive electrode coating 113 and the depth H of the thinning groove 1131 ≤ 50% of the thickness of the positive electrode coating 113 help to further optimize the capacitance of the electrochemical device and the mechanical strength of the positive electrode 110 in the corner region 170.

[0042] The depth H of the thinning groove 1131 can be the distance between the groove opening and the groove end wall.

[0043] The depth H of the thinning groove 1131 can be 30%, 36%, 40%, 45%, 50% of the thickness of the positive electrode coating 113, or any other percentage value between any two of the above percentage values.

[0044] In some embodiments, the positive current collector 111 may have a first surface 1111 disposed facing the center of the electrode assembly 100 (e.g., Figure 3 As shown), the first surface 1111 can be coated with a positive electrode coating 113. The positive electrode coating 113 coated on the first surface 1111 can be provided with a thinning groove 1131, which can reduce the thickness of the positive electrode coating 113 inside the positive electrode sheet 110, and help improve the stress concentration and lithium plating problems in the rising corner region 170.

[0045] As an example, the positive electrode coating 113 coated on the first surface 1111 is indirectly coated on the negative electrode sheet 130 through the separator 150. In the corner region 170 of the electrode assembly 100, the positive electrode coating 113 coated on the first surface 1111 is affected by bending, and its stress concentration problem is more obvious. Therefore, a thinning groove 1131 is provided on the positive electrode coating 113 on the first surface 1111 to better improve the stress concentration problem of the positive electrode coating 113 in the corner region 170.

[0046] It should be noted that the positive current collector 111 may also include a second surface 1113 (such as...). Figure 3 As shown), the second surface 1113 and the first surface 1111 are spaced apart and opposite each other along the thickness direction Z of the current collector. The second surface 1113 is the surface of the positive current collector 111 facing away from the center of the electrode assembly 100. The second surface 1113 may also be coated with a positive electrode coating 113 to improve the capacity of the electrochemical device.

[0047] In some embodiments, the positive electrode 110 may include a plurality of straight sections 115 and a plurality of bent sections 117 (e.g., ...). Figure 2 (As shown).

[0048] Among them, multiple straight sections 115 and multiple bent sections 117 can be alternately distributed along the winding direction X of the positive electrode 110. Each straight section 115 is located in the straight region 190, and each bent section 117 is located in the corner region 170. Specifically, each bent section 117 is distributed in two corner regions 170.

[0049] The positive electrode coating 113 located in the bending section 117 may be provided with a thinning groove 1131 to improve the problem of lithium plating in the corner region 170.

[0050] In some embodiments, the thinning groove 1131 may be spaced apart from the boundary of the bending section 117, thereby preventing the thinning groove 1131 from penetrating the boundary of the positive electrode coating 113 and reducing the possibility of the boundary of the bending section 117 cracking or deforming due to reduced mechanical strength.

[0051] Please see Figure 1 , Figure 2 and Figure 4 In some embodiments, 50% of the length L1 of the bent section 117 along the winding direction X is less than or equal to 70% of the maximum extension length L2 of the thinning groove 1131 along the winding direction X. This allows more positive electrode active material to be retained in the corner region 170, which helps to ensure the capacitance of the electrochemical device. In addition, it can also ensure the mechanical strength of the positive electrode 110 in the corner region 170, reducing the risk of breakage of the positive electrode 110 in the corner region 170. Furthermore, it also helps the positive electrode coating 113 to have a portion of the area in the corner region 170 that is not thinned by the thinning groove 1131 to support the positive electrode 110, which helps to reduce the problem of corner region 170 collapse.

[0052] As an example, the maximum extension length of the thinning groove 1131 along the winding direction X can be 50%, 58%, 62%, 65%, 70% of the length of the bent section 117 along the winding direction X, or any other percentage value between any two of the above percentage values.

[0053] In some embodiments, 70% of the width W1 of the bent section 117 along the width direction Y is less than or equal to 80% of the maximum width W2 of the thinning groove 1131 along the width direction Y. The width direction Y is perpendicular to the winding direction X, i.e., W2 < W1. This allows more positive electrode active material to be retained to ensure the capacitance of the electrochemical device. In addition, it can also ensure the mechanical strength of the positive electrode 110 in the corner region 170, reducing the risk of breakage of the positive electrode 110 in the corner region 170. Furthermore, it helps the positive electrode coating 113 to have a portion of the area in the corner region 170 that is not thinned by the thinning groove 1131 to support the positive electrode 110, which helps to reduce the problem of corner region 170 collapse.

[0054] As an example, the maximum width of the thinning groove 1131 along the width direction Y can be 70%, 72%, 77%, 79%, 80% of the width of the bending segment 117 along the width direction Y, or any other percentage value between any two of the above percentage values.

[0055] The positive electrode 110, the separator 150 and the negative electrode 130 can be stacked and wound around the winding axis to form a core structure, with the width direction Y parallel or approximately parallel to the extension direction of the winding axis.

[0056] In some embodiments, the electrochemical device further includes adhesive tape 300, which covers the thinning groove 1131. Specifically, the adhesive tape 300 can be adhered to the positive electrode coating 113 and cover the thinning groove 1131, thereby shielding the burrs on the edge of the thinning groove 1131. This helps the positive electrode coating 113 to be smoother in the area of ​​the thinning groove 1131, which can improve the situation where burrs puncture the separator 150 and cause a short circuit. It can also further improve the CB value of the corner region 170 and reduce the problem of lithium plating in the corner region 170 of the positive electrode 110.

[0057] It should be noted that when there are multiple thinning grooves 1131, the adhesive tape 300 can cover each thinning groove 1131 at the same time, or each thinning groove 1131 can correspond to one adhesive tape 300.

[0058] In some embodiments, the difference between the length L3 of the adhesive tape 300 along the winding direction X of the positive electrode 110 and the length L2 of the thinning groove 1131 along the winding direction X is ≤0.3mm (i.e., L3 > L2). This helps the adhesive tape 300 to more completely cover the thinning groove 1131 along the winding direction X, reducing the exposure of the edge of the thinning groove 1131 along the winding direction X. In addition, it can also prevent the adhesive tape 300 from covering more of the positive electrode coating 113, thus affecting the capacity of the electrochemical device.

[0059] As an example, the difference between the length of the adhesive tape 300 along the winding direction X of the positive electrode 110 and the length of the thinning groove 1131 along the winding direction X can be 0.1 mm, 0.15 mm, 0.2 mm, 0.3 mm, or any other value between any two of the above.

[0060] In some embodiments, the difference between the width W3 of the adhesive tape 300 along the width direction Y of the positive electrode 110 and the width W1 of the positive electrode 110 along the width direction Y is ≤0.4mm. This helps the adhesive tape 300 to more completely cover the thinning groove 1131 along the width direction Y, reducing the exposure of the edge of the thinning groove 1131 along the width direction Y. In addition, it can also avoid the situation where the size of the adhesive tape 300 along the width direction Y is too large, resulting in too much of the adhesive tape 300 being exposed on the electrode assembly 100, thus reducing the impact on the appearance of the electrode assembly 100.

[0061] It should be noted that the positive electrode coating 113 can be coated on the entire surface of the positive electrode current collector 111 in the bending section 117 region. In this case, the width of the positive electrode sheet 110 along the width direction Y and the width of the positive electrode coating 113 along the width direction Y are equal, both being W1.

[0062] In the electrochemical device and electronic device provided in this application embodiment, a wound core structure can be formed by stacking and winding the positive electrode 110, the separator 150, and the negative electrode 130. By providing a thinning groove 1131 on the positive electrode coating 113 in the corner region 170, the capacity of the positive electrode coating 113 in the corner region 170 can be reduced, the CB value of the corner region 170 can be increased, and the problem of lithium plating in the corner region 170 can be improved. In addition, the thinning groove 1131 can also provide a gap between the positive electrode 110 and the negative electrode 130 to improve the problem of stress concentration in the corner region 170, and further improve the problem of lithium plating in the corner region 170. Moreover, the thickness of the area of ​​the positive electrode coating 113 where the thinning groove 1131 is not provided remains unchanged, and this area can play a supporting role, which helps to improve the problem of collapse in the corner region 170.

[0063] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An electrochemical device, characterized in that, The device includes an electrode assembly comprising a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode, wherein the positive electrode, the separator, and the negative electrode are stacked and wound together; the positive electrode includes a positive current collector and a positive electrode coating coated on the surface of the positive current collector, and the negative electrode includes a negative current collector and a negative electrode coating coated on the surface of the negative current collector; The electrode assembly has a flat region and a corner region, and the positive electrode coating has a thinning groove in the corner region.

2. The electrochemical device according to claim 1, characterized in that, The depth of the thinning groove is less than the thickness of the positive electrode coating.

3. The electrochemical device according to claim 2, characterized in that, The thickness of the positive electrode coating is 30% ≤ the depth of the thinning groove is ≤ 50% of the thickness of the positive electrode coating.

4. The electrochemical device according to claim 1, characterized in that, The positive current collector has a first surface facing the center of the electrode assembly, the first surface is coated with the positive electrode coating, and the positive electrode coating coated on the first surface is provided with the thinning groove.

5. The electrochemical device according to claim 1, characterized in that, The positive electrode sheet includes multiple straight segments and multiple bent segments that are alternately distributed along the winding direction; each of the straight segments is located in the straight region, and each of the bent segments is located in the corner region; the positive electrode coating located in the bent segment is provided with the thinning groove; Wherein, 50% of the length of the bent section along the winding direction is less than or equal to the maximum extension length of the thinning groove along the winding direction and less than or equal to 70% of the length of the bent section along the winding direction; And / or, 70% of the width of the bent section along the width direction is less than or equal to the maximum width of the thinning groove along the width direction is less than or equal to 80% of the width of the bent section along the width direction, and the width direction is perpendicular to the winding direction.

6. The electrochemical device according to claim 1, characterized in that, The positive electrode sheet includes multiple straight segments and multiple bent segments that are alternately distributed along the winding direction; each of the straight segments is located in the straight region, and each of the bent segments is located in the corner region; The positive electrode coating located in the bending section is provided with the thinning groove, and the thinning groove and the boundary of the bending section are spaced apart.

7. The electrochemical device according to claim 1, characterized in that, The electrochemical device also includes adhesive paper covering the thinning tank.

8. The electrochemical device according to claim 7, characterized in that, The difference between the length of the adhesive tape along the winding direction of the positive electrode and the length of the thinning groove along the winding direction is 0.1 mm ≤ 0.3 mm.

9. The electrochemical device according to claim 7, characterized in that, 0.1mm ≤ the difference between the width of the adhesive tape along the width direction of the positive electrode and the width of the positive electrode along the width direction ≤ 0.4mm.

10. An electronic device, characterized in that, Includes the electrochemical device according to any one of claims 1 to 9.

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