Electrochemical device and electronic device

Abstract

An electrochemical device comprises a shell, an electrode assembly and electrolyte, wherein the electrode assembly and the electrolyte are arranged in the shell. The electrode assembly comprises pole pieces and isolating membranes arranged between the adjacent pole pieces. The isolating membrane comprises a porous base material and a first bonding layer arranged on the surface of the porous base material. The first bonding layer comprises a plurality of first bonding areas arranged at intervals. The thickness direction of the electrode assembly is defined as the first direction, in the first direction, a circumscribed rectangle of the projection of the electrode assembly has a diagonal line and a first side, the included angle between the diagonal line and the first side is theta 1, the included angle between the projection of the first bonding area and the first side is theta 2, and theta 1 / 2 < = theta 2 < = (theta 1 / 2 + 45 degrees). The invention also provides an electronic device with the electrochemical device. The electrochemical device provided by the invention can give consideration to both interface adhesion and electrolyte transmission capability, and has improved deformation resistance and cycle performance.

Description

[0001] This application is a divisional application of the application with the application number 202110338853.6, the application date of March 30, 2021, and the invention title of "Electrochemical Device and Electronic Device". Technical Field

[0002] This application relates to the field of energy storage technologies, and particularly relates to an electrochemical device and an electronic device having the electrochemical device. Background Art

[0003] Electrochemical devices (such as batteries) are widely used in electronic devices such as electronic mobile devices, power tools, and electric vehicles. With the development of such electronic devices, people's requirements for the cycling performance of electrochemical devices are becoming increasingly strict. Summary of the Invention

[0004] To solve the deficiencies of the prior art, it is necessary to provide an electrochemical device.

[0005] In addition, it is also necessary to provide an electronic device having the above-mentioned electrochemical device.

[0006] This application provides an electrochemical device, including a housing and an electrode assembly and an electrolyte disposed within the housing. The electrode assembly includes electrode sheets and a separator disposed between adjacent electrode sheets. The separator includes a porous substrate and a first bonding layer disposed on the surface of the porous substrate. The first bonding layer includes a plurality of first bonding regions disposed at intervals. Define the thickness direction of the electrode assembly as the first direction. In the first direction, the circumscribed rectangle of the projection of the electrode assembly has a diagonal and a first side, and the included angle between the diagonal and the first side is θ1, and the included angle between the projection of the first bonding region and the first side is θ2, where θ1 / 2 ≤ θ2 ≤ (θ1 / 2 + 45°).

[0007] This application provides that the first bonding layer of the separator includes a plurality of first bonding regions disposed at intervals, which improves the interfacial bonding force between the separator and the electrode sheet. At the same time, the gap between two adjacent first bonding regions reserves space for electrolyte transmission. Therefore, the requirements for interfacial bonding force and electrolyte transmission can be taken into account simultaneously. Furthermore, this application sets θ1 / 2 ≤ θ2 ≤ (θ1 / 2 + 45°), such that the first bonding region is inclined with respect to the first side of the circumscribed rectangle of the projection of the electrode assembly in the thickness direction. Therefore, the bonding force of the first bonding layer is continuously distributed in the direction of the first side, improving the anti-deformation ability of the electrochemical device; at the same time, by setting the relationship between θ2 and θ1, the inclination angle of the first bonding region is also within a certain deviation range compared with the inclination angle of the diagonal of the circumscribed rectangle. Therefore, each first bonding region can form a relatively stable triangular fixing relationship with the end and side portions of the electrode assembly, further improving the anti-deformation ability of the electrochemical device and improving the cycling performance.

[0008] In some possible implementation manners, the separator membrane further includes a second adhesive layer, and the porous substrate is located between the first adhesive layer and the second adhesive layer. The second adhesive layer includes a plurality of second adhesive regions arranged at intervals. Therefore, the gap between two adjacent second adhesive regions can also serve as a channel for electrolyte transmission, further improving the electrolyte transmission performance. In the first direction, the included angle between the projection of the second adhesive region and the projection of the first adhesive region is θ3, where 0 < θ3 < 180°. Therefore, the second adhesive region is also inclined, so that the adhesive force of the second adhesive layer is continuously distributed in the direction of the first side, further improving the anti-deformation ability of the electrochemical device.

[0009] In some possible implementation manners, θ3 = 180° - 2θ2. By further defining the relationship between θ3 and θ2, the anti-deformation ability of the electrode assembly can be further improved.

[0010] In some possible implementation manners, θ2 = θ1. By further defining that θ2 is equal to θ1, the most stable triangular fixing relationship is formed between each first adhesive region and the second end portion and the side portion of the electrode assembly, thereby further improving the anti-deformation ability of the electrode assembly.

[0011] In some possible implementation manners, the direction from one first adhesive region to another adjacent first adhesive region is defined as the second direction. In the second direction, the width of the first adhesive region is d1 mm, and the distance between adjacent first adhesive regions is d2 mm. d1 and d2 satisfy: 0.1 < d1 < 10, 0.1 < d2 < 10. Among them, when d1 is too small, the adhesive force between the first adhesive layer and the pole piece decreases, and the anti-deformation ability also decreases accordingly; when d1 is too large, d2 correspondingly decreases, so that the space available for electrolyte transmission decreases, and the electrolyte infiltration is poor. When d2 is too small, the space available for electrolyte transmission also decreases, and the electrolyte infiltration is poor; when d2 is too large, d1 correspondingly decreases, and the adhesive force between the first adhesive layer and the pole piece also decreases, and the anti-deformation ability also decreases accordingly.

[0012] In some possible implementation manners, the direction from one first adhesive region to another adjacent first adhesive region is defined as the second direction. In the second direction, the width of the first adhesive region is d1 mm, and the distance between adjacent first adhesive regions is d2 mm. d1 and d2 satisfy: 0.1 < d1 / d2 < 5. Among them, when d1 / d2 is too small, the area ratio of the first adhesive region decreases, and the adhesive force between the first adhesive layer and the pole piece also decreases, and the anti-deformation ability also decreases accordingly; when d1 / d2 is too large, the area ratio of the first adhesive region increases, and the space available for electrolyte transmission also decreases, and the electrolyte infiltration is poor.

[0013] In some possible implementation manners, in the first direction, the thickness of the first adhesive layer is t1 μm, and 0.15 < t1d1 / (d1 + d2) < 2. Wherein, when t1d1 / (d1 + d2) is too small, the proportion of the diffusion area of the first adhesive layer after being heated and softened decreases, which will also cause the adhesive force between the first adhesive layer and the electrode tab to decrease, and the anti-deformation ability will also decrease accordingly; when t1d1 / (d1 + d2) is too large, the proportion of the diffusion area of the first adhesive layer after being heated and softened increases, which also makes the space available for electrolyte transmission decrease, resulting in poor electrolyte infiltration.

[0014] In some possible implementation manners, in the first direction, the thickness of the first adhesive layer is t1 μm, and 0.1 ≤ t1 ≤ 6. Wherein, when t1 is too small, the adhesive force between the first adhesive layer and the electrode tab decreases; when t1 is too large, the air permeability of the entire separator will be reduced, resulting in poor electrolyte transmission.

[0015] In some possible implementation manners, multiple first adhesive regions are parallel to each other. Wherein, when multiple first adhesive regions are parallel to each other, there may be a certain included angle between two adjacent first adhesive regions, and the included angle is from -5° to +5°.

[0016] In some possible implementation manners, each first adhesive region is continuously or discontinuously arranged. Wherein, the gap in each discontinuously arranged first adhesive region can also serve as a channel for electrolyte transmission, further improving the electrolyte transmission performance.

[0017] In some possible implementation manners, in the first direction, the projection of the electrode assembly includes a rectangle, an arc or an L shape. Therefore, the electrochemical device can be arranged according to the shape of the internal space of the electronic device, so as to make full use of the space inside the electronic device and improve the capacity of the electrochemical device.

[0018] In some possible implementation manners, the electrode assembly further includes a tab electrically connected to the electrode tab. In the first direction, the projection of the tab extends from the opposite side of the first side, facilitating the electrical connection of the tab to an external component.

[0019] In some possible implementation manners, the electrode assembly includes a wound structure or a stacked structure.

[0020] In some possible implementation manners, the porous substrate includes any one of the following polymers or a polymer film, a multi-layer polymer film, or a non-woven fabric formed by a mixture of two or more of the following: polyolefin, polyvinylidene fluoride, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex or polyphenylenediamine terephthalate. These polymers have high thermal stability and are easy to coat the first adhesive layer on the porous substrate. In addition, these polymers have good toughness and are easy to bend.

[0021] In some possible implementation manners, the first adhesive layer includes an adhesive material, and the adhesive material includes at least one of a copolymer of vinylidene fluoride - hexafluoropropylene, a copolymer of vinylidene fluoride - trichloroethylene, polymethyl methacrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, a copolymer of ethylene - vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylated amylose, cyanoethylated polyvinyl alcohol, cyanoethylated cellulose, cyanoethylated sucrose, amylopectin, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, a copolymer of acrylonitrile - styrene - butadiene, polyvinyl alcohol, polyvinyl ether, polytetrafluoroethylene, polyhexafluoropropylene, a copolymer of styrene - butadiene, or polyvinylidene fluoride. These polymers can produce a strong adhesive effect and bond the separator and the electrode sheet together.

[0022] This application also provides an electronic device, including the above electrochemical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the electrochemical device provided by an embodiment of this application.

[0024] Figure 2 It is Figure 1 The front view of the electrode assembly of the electrochemical device shown in some embodiments.

[0025] Figure 3 It is Figure 1 The front view of the electrode assembly of the electrochemical device shown in some other embodiments.

[0026] Figure 4 It is Figure 1 The front view of the electrode assembly of the electrochemical device shown in some further embodiments.

[0027] Figure 5 It is Figure 2 The top view of the electrode assembly shown in some embodiments.

[0028] Figure 6 It is Figure 2 The top view of the electrode assembly shown in some other embodiments.

[0029] Figure 7 It is Figure 5 The sectional view of the electrode assembly shown along V-II-VII.

[0030] Figure 8 It is Figure 2 The front view of the separator of the electrode assembly shown in some embodiments.

[0031] Figure 9 It isFigure 2 Front view of the separator of the electrode assembly shown in some other embodiments.

[0032] Figure 10 is Figure 2 Back view of the separator of the electrode assembly shown.

[0033] Figure 11 Schematic structural diagram of an electronic device provided by an embodiment of the present application.

[0034] Description of main element symbols

[0035] Electronic device 1

[0036] Housing 10

[0037] Main body portion 11

[0038] Encapsulation portion 12

[0039] Electrode assembly 20

[0040] First pole piece 21

[0041] Second pole piece 22

[0042] Separator 23

[0043] First tab 30

[0044] Second tab 40

[0045] Electrochemical device 100

[0046] Top surface 111

[0047] Bottom surface 112

[0048] Upper surface 113

[0049] First side surface 114

[0050] Second side surface 115

[0051] Projection 200

[0052] First side 201

[0053] Second side 202

[0054] Diagonal 203

[0055] First current collector 211

[0056] First active material layer 212

[0057] Second current collector 221

[0058] Second active material layer 222

[0059] Porous substrate 230

[0060] First adhesive layer 231

[0061] Second adhesive layer 232

[0062] First bonding area 2311

[0063] Second bonding area 2321

[0064] Circumscribed rectangle R

[0065] Gaps G1, G2, G3

[0066] First direction D1

[0067] Second direction D2

[0068] Third direction D3

[0069] Fourth direction D4

[0070] Width d1

[0071] Distance d2

[0072] Thickness t1

[0073] The following specific embodiments will further illustrate the present application in conjunction with the above drawings. Specific embodiments

[0074] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0075] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0076] Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0077] Electrochemical devices generally include electrode sheets and a separator disposed between adjacent electrode sheets. A separator with high adhesion performance is generally used to tightly bond the adjacent electrode sheets and the separator together, ensuring the interfacial adhesion force between the separator and the electrode sheets and reducing the expansion deformation during gas generation inside the electrochemical device. However, setting a separator with high adhesion performance will result in a smaller gap between the separator and the electrode sheets, making it difficult for the electrolyte to fully infiltrate the electrode sheets. Especially for wound batteries, the problem of uneven electrolyte distribution is more likely to occur in the corner area of the electrode assembly, leading to the generation of purple spots and lithium deposition during the cycling process, which affects the cycling performance of the electrochemical device.

[0078] Please refer to Figure 1 , an embodiment of the present application provides an electrochemical device 100, including a housing 10, an electrode assembly 20 (shown in Figure 5 and Figure 6 ) received in the housing 10, an electrolyte, a first pole ear 30, and a second pole ear 40. Figure 5 and Figure 6 show that the electrochemical device 100 includes one electrode assembly 20. However, it can be understood that in order to achieve high-voltage output, the electrochemical device 100 may also include multiple electrode assemblies 20 connected in series, and the present application does not make any restrictions.

[0079] As Figure 5 and Figure 6 shown, the electrode assembly 20 includes electrode sheets and a separator 23 disposed between adjacent electrode sheets. Among them, the electrode sheets include a first electrode sheet 21 and a second electrode sheet 22, and the separator 23 is disposed between the first electrode sheet 21 and the second electrode sheet 22. The separator 23 is used to prevent the first electrode sheet 21 and the second electrode sheet 22 from directly contacting and short-circuiting. In some embodiments, the electrode assembly 20 is obtained by winding the first electrode sheet 21, the separator, and the second electrode sheet 22, that is, the electrode assembly 20 is a wound structure. In other embodiments, the electrode assembly 20 may also be obtained by laminating the first electrode sheet 21, the separator, and the second electrode sheet 22, that is, the electrode assembly 20 is a laminated structure.

[0080] The first pole ear 30 and the second pole ear 40 are respectively electrically connected to the electrode assembly 20 and extend out of the housing 10 to connect to external components (not shown in the figure). Specifically, the first electrode sheet 21 includes a first current collector 211 and a first active material layer 212 disposed on the surface of the first current collector 211, and the first pole ear 30 is electrically connected to the first current collector 211. The second electrode sheet 22 includes a second current collector 221 and a second active material layer 222 disposed on the surface of the second current collector 221, and the second pole ear 40 is electrically connected to the second current collector 221. In some embodiments, the first electrode sheet 21 is a positive electrode sheet, and the second electrode sheet 22 is a negative electrode sheet.

[0081] As Figure 1As shown, the housing 10 may be a packaging bag obtained by encapsulating with a packaging film. That is, the electrochemical device 100 may be a soft-pack battery. At this time, the housing 10 includes a main body portion 11 and a packaging portion 12. The main body portion 11 is used to accommodate the electrode assembly 20 and the electrolyte. The packaging portion 12 is connected to the main body portion 11, and the first tab 30 and the second tab 40 extend out of the packaging portion 12. Among them, the main body portion 11 includes a top surface 111, a bottom surface 112, an upper surface 113, a lower surface (not shown in the figure), a first side surface 114 and a second side surface 115. The top surface 111 and the bottom surface 112 are opposite. The upper surface 113 and the lower surface are opposite and are connected between the top surface 111 and the bottom surface 112. The first side surface 114 and the second side surface 115 are opposite and are connected between the top surface 111 and the bottom surface 112. The packaging portion 12 is connected to the top surface 111. In other embodiments, the electrochemical device 100 is not limited to a soft-pack battery and may also be a steel-shell battery or an aluminum-shell battery, etc., and the present application does not make any restrictions.

[0082] Please refer to Figure 7 , the separator 23 includes a porous substrate 230 and a first adhesive layer 231 provided on the surface of the porous substrate 230, and the first adhesive layer 231 adheres to the first electrode sheet 21. In another embodiment, the first adhesive layer 231 may also adhere to the second electrode sheet 22.

[0083] Please refer to Figure 8 , the first adhesive layer 231 includes a plurality of first adhesive regions 2311 arranged at intervals. That is, there is a gap G1 between two adjacent first adhesive regions 2311. In some embodiments, the plurality of first adhesive regions 2311 are arranged in parallel. It can be understood that when two elements are arranged in parallel, there may be a certain included angle between the two elements, and the included angle is -5° to +5°, so it is not required that the two elements must be strictly parallel.

[0084] Define the thickness direction (i.e., the direction from the upper surface 113 to the lower surface), the length direction (i.e., the direction from the bottom surface 112 to the top surface 111), and the width direction (i.e., the direction from the first side surface 114 to the second side surface 115) of the electrode assembly 20 as the first direction D1, the third direction D3, and the fourth direction D4 respectively. Among them, the third direction D3 is the direction in which the first tab 30 and the second tab 40 extend. Please refer to Figure 2 , in some embodiments, in the first direction D1, the projection 200 of the electrode assembly 20 is rectangular and has a first side 201, a second side 202, and a diagonal 203 connecting the first side 201 and the second side 202.

[0085] Among them, as Figure 2As shown, the electrode assembly 20 has a first end 20a, a second end 20b, and a side portion 20c connected between the first end 20a and the second end 20b. The first end 20a is the head of the electrode assembly 20 where the first tab 30 and the second tab 40 are provided. The second end 20b is the tail of the electrode assembly 20 opposite to the head. The projection of the second end 20b in the first direction D1 forms a first side 201, and the projection of the side portion 20c in the first direction D1 forms a second side 202. In this case, in the first direction D1, the projections of the first tab 30 and the second tab 40 extend from the opposite side of the first side 201, facilitating the electrical connection of the first tab 30 and the second tab 40 to external components.

[0086] Please refer to Figure 2 and Figure 8 , define the included angle between the diagonal 203 and the first side 201 as θ1. Since the diagonal 203 of the circumscribed rectangle R is inclined with respect to the first side 201, that is, 0° < θ1 < 90°. The included angle between the projection of the first bonding region 2311 and the first side 201 is θ2, and θ1 and θ2 satisfy the following relationship: θ1 / 2 ≤ θ2 ≤ (θ1 / 2 + 45°).

[0087] As Figure 8 shown, in some embodiments, each first bonding region 2311 may be strip-shaped and disposed on the surface of the porous substrate 230. That is, each first bonding region 2311 is continuously disposed. At this time, the projection of each first bonding region 2311 is also strip-shaped, and the included angle θ2 between the projection of the first bonding region 2311 and the first side 201 is the included angle between the strip-shaped projection and the first side 201. As Figure 9 shown, in another embodiment, each first bonding region 2311 may also be discontinuously disposed, such as being disposed on the surface of the porous substrate 230 in a plurality of block shapes or a plurality of island shapes. At this time, the projection of each first bonding region 2311 is also in a plurality of block shapes or a plurality of island shapes, and the included angle θ2 between the projection of the first bonding region 2311 and the first side 201 is the included angle between the connecting line of the block-shaped or island-shaped projections and the first side 201.

[0088] Among them, a gap G2 is also provided in each of the discontinuously disposed first bonding regions 2311, which can serve as a channel for electrolyte transmission, further improving the electrolyte transmission performance.

[0089] The first adhesive layer 231 of the separator film provided in this application includes a plurality of first adhesive zones 2311 arranged at intervals. The first adhesive zones 2311 can bond the first electrode tab 21 or the second electrode tab 22, improving the interfacial adhesion between the separator film 23 and the electrode tab, reducing the expansion deformation during gas generation inside the electrochemical device 100, that is, improving the anti-deformation ability of the electrochemical device 100, reducing the risk of deformation of the electrode assembly and damage to the structure, and maintaining the smoothness of the entire conductive network in the electrode assembly 20, thereby improving the cycling performance of the electrochemical device 100. At the same time, there is a gap G1 between two adjacent first adhesive zones 2311, thus reserving space for electrolyte transmission. After injection of the electrolyte, the electrolyte can flow through the above-mentioned gap G1 and fully wet the electrode tab, which also helps to improve the cycling performance of the electrochemical device 100. The electrochemical device 100 of this application can take into account the requirements of both interfacial adhesion and electrolyte transmission at the same time.

[0090] Furthermore, in this application, it is set that θ1 / 2 ≤ θ2 ≤ (θ1 / 2 + 45°). Since 0° < θ1 < 90°, then 0° < θ2 < 90°, so that the projection of the first adhesive zone 2311 is also inclined to the first side 201. Therefore, the adhesive force of the first adhesive layer 231 is continuously distributed in the direction of the first side 201, that is, the adhesive force between the separator film 23 and the electrode tab is continuously distributed in the direction of the first side 201, improving the anti-deformation ability of the electrochemical device 100, thereby improving the cycling performance. At the same time, by setting the relationship between θ2 and θ1, the inclination angle of the first adhesive zone 2311 also has a certain deviation range compared with the inclination angle of the diagonal 203 of the circumscribed rectangle R. Therefore, each first adhesive zone 2311 can form a relatively stable triangular fixing relationship with the second end portion 20b and the side portion 20c of the electrode assembly 20, which can also further improve the anti-deformation ability of the electrochemical device 100, thereby improving the cycling performance.

[0091] It can be understood that in order to improve the competitiveness of electronic devices, some consumer electronic devices are turning towards being shaped in a non-standard way, and an electrochemical device with a non-standard shape can make full use of the irregular space inside such electronic devices, thereby increasing the capacity of the entire electrochemical device. Therefore, in this application, in the first direction D1, the projection 200 of the electrode assembly 20 is not limited to a rectangle, but can also be other non-standard shapes. Such as Figure 3 and Figure 4 As shown, in another embodiment, when the electrode assembly 20 is a stacked structure, in the first direction D1, the projection 200 of the electrode assembly 20 is arc-shaped or L-shaped. At this time, the circumscribed rectangle R of the projection 200 of the electrode assembly 20 also has a first side 201, a second side 202, and a diagonal 203 connecting the first side 201 and the second side 202. It can be understood that, as Figure 2 shown, when the projection 200 of the electrode assembly 20 is a rectangle, the circumscribed rectangle R of the projection 200 is the projection 200 itself.

[0092] In some embodiments, the porous substrate 230 includes a polymer film, a multilayer polymer film, or a non-woven fabric formed of any one of the following polymers or a mixture of two or more polymers: polyolefin, polyvinylidene fluoride, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex, and poly(p-phenylene terephthalamide). Such polymers have high thermal stability and are easy to be surface-treated, so that it is easy to coat the first adhesive layer 231 on the porous substrate 230. In addition, such polymers have good toughness and are easy to bend.

[0093] The first adhesive layer 231 includes an adhesive material, and the adhesive material includes at least one of the following polymers: copolymer of vinylidene fluoride and hexafluoropropylene, copolymer of vinylidene fluoride and trichloroethylene, polymethyl methacrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, copolymer of ethylene and vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylated amylose, cyanoethylated polyvinyl alcohol, cyanoethylated cellulose, cyanoethylated sucrose, amylose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, copolymer of acrylonitrile, styrene and butadiene, polyvinyl alcohol, polyvinyl ether, polytetrafluoroethylene, polyhexafluoropropylene, copolymer of styrene and butadiene, or polyvinylidene fluoride. These polymers can produce strong adhesion and bond the separator 23 to the first electrode 21 or the second electrode 22 together.

[0094] As Figure 7 shown, in some embodiments, the separator 23 further includes a second adhesive layer 232, and the porous substrate 230 is located between the first adhesive layer 231 and the second adhesive layer 232. When the first adhesive layer 231 bonds to the first electrode 21, the second adhesive layer 232 bonds to the second electrode 22. Please refer to Figure 10 together, the second adhesive layer 232 includes a plurality of second adhesive regions 2321 arranged at intervals. That is, there is also a gap G3 between two adjacent second adhesive regions 2321, serving as a channel for electrolyte transmission. Therefore, the arrangement of the second adhesive regions 2321 further improves the wetting effect of the electrolyte. In some embodiments, the plurality of second adhesive regions 2321 are arranged in parallel.

[0095] In the first direction D1, the included angle between the projection 200 of the second adhesive region 2321 and the projection 200 of the first adhesive region 2311 is θ3, where 0° < θ3 < 180°. That is, the second adhesive region 2321 is also inclined to the first side 201. Therefore, the adhesive force of the second adhesive layer 232 is also continuously distributed in the direction of the first side 201, further improving the anti-deformation ability of the electrochemical device 100.

[0096] Further, θ2 and θ3 may also satisfy the following relationship: θ3 = 180° - 2θ2. By further defining the relationship between θ3 and θ2, the anti-deformation ability of the electrode assembly 20 can be further improved.

[0097] In some embodiments, θ2 = θ1. By further defining that θ2 is equal to θ1, the most stable triangular fixing relationship is formed between each first bonding region 2311 and the second end portion 20b and the side portion 20c of the electrode assembly 20, thereby further improving the anti-deformation ability of the electrode assembly 20.

[0098] As Figure 8 shown, in some embodiments, the direction from one first bonding region 2311 to another adjacent first bonding region 2311 is defined as the second direction D2. In the second direction D2, the width of the first bonding region 2311 is d1 mm, and the distance between adjacent first bonding regions 2311 is d2 mm. d1 and d2 satisfy: 0.1 < d1 < 10, 0.1 < d2 < 10. Among them, when d1 is too small, the bonding force between the first bonding layer 231 and the pole piece decreases, and the anti-deformation ability also decreases accordingly; when d1 is too large, d2 correspondingly decreases when the area of the pole piece is certain, thereby reducing the space available for electrolyte transmission and resulting in poor electrolyte infiltration. When d2 is too small, the space available for electrolyte transmission is also reduced, resulting in poor electrolyte infiltration; when d2 is too large, d1 correspondingly decreases when the area of the pole piece is certain, and the bonding force between the first bonding layer 231 and the pole piece also decreases, and the anti-deformation ability also decreases accordingly.

[0099] In some embodiments, d1 and d2 satisfy: 0.1 < d1 / d2 < 5. Among them, when d1 / d2 is too small, the area ratio of the first bonding region 2311 decreases, and the bonding force between the first bonding layer 231 and the pole piece also decreases, and the anti-deformation ability also decreases accordingly; when d1 / d2 is too large, the area ratio of the first bonding region 2311 increases, and the space available for electrolyte transmission is also reduced, resulting in poor electrolyte infiltration.

[0100] In some embodiments, in the first direction D1, the thickness of the first bonding layer 231 is t1 μm, and 0.15 < t1d1 / (d1 + d2) < 2. Among them, when t1d1 / (d1 + d2) is too small, the area ratio of the diffusion area of the first bonding layer 231 after being heated and softened decreases, and the bonding force between the first bonding layer 231 and the pole piece also decreases, and the anti-deformation ability also decreases accordingly; when t1d1 / (d1 + d2) is too large, the area ratio of the diffusion area of the first bonding layer 231 after being heated and softened increases, and the space available for electrolyte transmission is also reduced, resulting in poor electrolyte infiltration.

[0101] Please refer to Figure 7 and Figure 8, in some embodiments, 0.1 ≤ t1 ≤ 6. Among them, when t1 is too small, the adhesion between the first adhesive layer 231 and the electrode tab decreases; when t1 is too large, the air permeability of the entire separator 23 will be reduced, resulting in poor electrolyte transmission.

[0102] Among them, the electrochemical device 100 of the present application can be all kinds of primary batteries, secondary batteries, fuel cells, solar cells and capacitors (such as supercapacitors). In particular, the secondary battery can be a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery and a lithium ion polymer secondary battery.

[0103] Please refer to Figure 11 , an embodiment of the present application further provides an electronic device 1, and the electronic device 1 includes the above-mentioned electrochemical device 100. The electronic device 1 of the present application can be, but is not limited to, a notebook computer, a pen input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, a liquid crystal TV, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power source, a motor, a car, a motorcycle, a moped, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery and a lithium ion capacitor, etc.

[0104] The following will describe the present application in detail through specific examples and comparative examples. Among them, taking the electrochemical device as a soft package battery cell as an example and combining the specific preparation process and test method to describe the present application. Those skilled in the art should understand that the preparation methods described in the present application are only examples, and any other suitable preparation methods are within the scope of the present application.

[0105] Comparative Example 1

[0106] The separator is double-sided coated and has a first adhesive layer and a second adhesive layer. The electrode assembly is obtained by sequentially laminating and winding the first electrode tab, the second electrode tab and the separator. In the first direction, the projection of the electrode assembly is rectangular, and the angle θ1 between the diagonal of the projection and the first side is 45°; the angle θ2 between the projection of the first adhesive region of the first adhesive layer and the first side is 90°; the angle θ3 between the projection of the second adhesive region of the second adhesive layer and the projection of the first adhesive region is 23°. The width d1 of the first adhesive region is 0.21 mm, the distance d2 between adjacent first adhesive regions is 0.04 mm, and the thickness t1 of the first adhesive region is 2 μm.

[0107] The electrode assembly and the electrolyte are encapsulated in an aluminum plastic film to obtain an electrochemical device.

[0108] Comparative Examples 2-5 and Examples 1-12

[0109] The difference from Comparative Example 1 is that: the values ​​of θ1, θ2 or θ3 are different; the second bonding layer is omitted from the isolation film; or, the first bonding layer and the second bonding layer are uniformly coated (i.e., the bonding layer is uniformly coated on the entire surface of the porous substrate).

[0110] The electrochemical devices of each embodiment and comparative example were subjected to a capacity retention test and a three-point bending test, and the corresponding test results were recorded in Table 1. The steps of the capacity retention test include: in a high-temperature furnace at 45 degrees Celsius, the electrochemical device is charged to 4.43V at a constant current of 1C, then charged to 0.05C at a constant voltage, then left to stand for 5 minutes, and then discharged to 3.0V at 0.7C. This discharge capacity is the first discharge capacity of the battery, which is calculated as 100%. The above charge and discharge steps are cycled 400 times in sequence, and the ratio of the discharge capacity of the electrochemical device after the cycle to the first capacity multiplied by 100% is the capacity retention rate.

[0111] The steps of the three-point bending test include: in a dry environment, fix the electrochemical device on two supporting points with a certain distance, and use a pressure head to apply pressure to the electrochemical device at the midpoint of the two supporting points. Then, record the displacement of the pressure head and the pressure on the electrochemical device corresponding to the displacement. When the recorded pressure value jumps (decreases sharply), it indicates that the electrochemical device has a fracture inside. At this time, the pressure value can be used to characterize the hardness of the electrochemical device.

[0112] Table 1

[0113]

[0114] From the data in Table 1, it can be seen that compared with Comparative Examples 1-4, since Examples 1-4 satisfy θ1 / 2≤θ2≤(θ1 / 2+45°), the electrochemical devices of Examples 1-4 have higher hardness (i.e., deformation resistance) and improved capacity retention. Among them, since Example 4 further satisfies θ2=θ1, it has higher deformation resistance and capacity retention. Comparative Example 5 has the lowest cycle performance because the bonding layer of the isolation membrane is uniformly coated.

[0115] Further, by comparing Examples 1-6, it can be seen that when θ1 / 2≤θ2≤(θ1 / 2+45°) is satisfied, as θ3 increases, the anti-deformation ability and capacity retention rate of the electrochemical device show a trend of first increasing and then decreasing, and when θ3=180°-2θ2, the electrochemical device has a higher anti-deformation ability and capacity retention rate. Therefore, the electrochemical device of Example 4 has a higher anti-deformation ability and capacity retention rate.

[0116] Furthermore, by comparing Examples 4 and 7-10, it can be seen that when θ3 = 180° - 2θ2 is satisfied, as θ2 increases, the anti-deformation ability and capacity retention rate of the electrochemical device show a trend of first increasing and then decreasing. When θ2 = θ1, the electrochemical device has higher anti-deformation ability and capacity retention rate. Therefore, the electrochemical device of Example 4 has higher anti-deformation ability and capacity retention rate.

[0117] Moreover, when θ2 = θ1 is satisfied, the specific value of θ1 can also be adjusted. By comparing Example 10, it can be seen that since Examples 11-12 satisfy θ2 = θ1, the electrochemical device has higher anti-deformation ability and capacity retention rate.

[0118] Examples 13-26

[0119] The difference from Example 1 is that the values of t1, d1, and d2 are further set, and the values of t1, d1, or d2 in Examples 13-26 are different.

[0120] The capacity retention rate test and three-point bending test were carried out on the electrochemical devices of each example and comparative example, and the corresponding test results were recorded in Table 2.

[0121] Table 2

[0122]

[0123] Among them, under the condition of satisfying θ1 / 2 ≤ θ2 ≤ (θ1 / 2 + 45°), the value of d2 will also affect the capacity retention rate of the electrochemical device. It can be seen from the data in Table 2 that compared with Examples 13-17, since d2 > 10 mm in Example 18, the adhesion force between the separator and the electrode sheet is relatively reduced, thereby relatively reducing the hardness (i.e., anti-deformation ability) of the electrochemical device, and at the same time the capacity retention rate is also relatively reduced.

[0124] Secondly, the value of d1 will also affect the capacity retention rate of the electrochemical device. Compared with Examples 16, 19-21, since d1 > 10 mm in Example 22, the space available for electrolyte transmission is reduced, and the capacity retention rate is also relatively reduced.

[0125] Thirdly, the value of d1 / d2 will also affect the capacity retention rate of the electrochemical device. By comparing Examples 19, 20, and 22, since d1 / d2 > 5 in Example 21, the capacity retention rate of the electrochemical device is relatively reduced.

[0126] Finally, the value of t1d1 / (d1 + d2) will also affect the capacity retention rate of the electrochemical device. By comparing with Examples 19, 23-24, since t1d1 / (d1 + d2) > 2 in Examples 25-26, the capacity retention rate of the electrochemical device is relatively reduced.

[0127] The above embodiments are only used to illustrate the technical solutions of the present application rather than to limit them. Although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced.

Claims

1. An electrochemical device, comprising a housing, and an electrode assembly and an electrolyte disposed within the housing, the electrode assembly including electrode sheets and a separator disposed between adjacent ones of the electrode sheets, wherein, the separator includes a porous substrate and a first adhesive layer disposed on a surface of the porous substrate, the first adhesive layer including a plurality of first adhesive regions spaced apart from each other; defining the thickness direction of the electrode assembly as a first direction, in the first direction, the circumscribed rectangle of the projection of the electrode assembly has a diagonal and a first side, and the included angle between the diagonal and the first side is θ1, and the included angle between the projection of the first adhesive region and the first side is θ2, θ1 / 2≤θ2≤(θ1 / 2 + 45°); the separator further includes a second adhesive layer, the porous substrate being located between the first adhesive layer and the second adhesive layer, the second adhesive layer including a plurality of second adhesive regions spaced apart from each other; in the first direction, the included angle between the projection of the second adhesive region and the projection of the first adhesive region is θ3, 45°≤θ3≤120°.

2. The electrochemical device according to claim 2, wherein, 80°≤θ3≤120°.

3. The electrochemical device according to claim 2, wherein, θ3 = 180° - 2θ2.

4. The electrochemical device according to claim 1, wherein, θ2 = θ1.

5. The electrochemical device according to claim 1, wherein, Defining the direction from one first adhesive region to another adjacent first adhesive region as a second direction, in the second direction, the width of the first adhesive region is d1 mm, and the distance between adjacent first adhesive regions is d2 mm, d1 and d2 satisfy at least one of the following conditions: 0.1 < d1 < 10, 0.1 < d2 < 10; 0.095 < d1 / d2 < 5.

6. The electrochemical device according to claim 5, wherein, 0.1 < d1 / d2 < 5.

7. The electrochemical device according to claim 5, wherein, In the first direction, the thickness of the first adhesive layer is t1 μm, 0.15 < t1d1 / (d1 + d2) < 2.

8. The electrochemical device according to claim 7, wherein, 0.17 < t1d1 / (d1 + d2) < 1.

86.

9. The electrochemical device according to claim 1, wherein, In the first direction, the thickness of the first adhesive layer is t1 μm, 0.1≤t1≤6.

10. The electrochemical device according to claim 9, wherein, 0.52≤t1≤2.4。 11. The electrochemical device according to claim 10, wherein, 2≤t1≤2.4。 12. The electrochemical device according to claim 1, wherein, The plurality of first adhesive regions are parallel to each other.

13. The electrochemical device according to claim 1, wherein, Each of the first adhesive regions is continuously or discontinuously provided.

14. The electrochemical device according to claim 1, wherein, In the first direction, the projection of the electrode assembly includes a rectangle, an arc or an L shape.

15. The electrochemical device according to claim 1, wherein, The electrode assembly further includes an electrode tab electrically connected to the electrode sheet, and in the first direction, the projection of the electrode tab extends from the opposite side of the first side.

16. The electrochemical device according to claim 1, wherein, The electrode assembly includes a wound structure or a stacked structure.

17. The electrochemical device according to claim 1, wherein, The porous substrate includes any one of the following polymers or a polymer film, a multi-layer polymer film, or a non-woven fabric formed by a mixture of two or more of: polyolefin, polyvinylidene fluoride, polyethylene terephthalate, cellulose, polyimide, polyamide, spandex or polyphenylenediamine terephthalate.

18. The electrochemical device according to claim 1, wherein, The first adhesive layer includes an adhesive material, and the adhesive material includes at least one of a copolymer of vinylidene fluoride - hexafluoropropylene, a copolymer of vinylidene fluoride - trichloroethylene, polymethyl methacrylate, polyacrylic acid, polyacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, a copolymer of ethylene - vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylated amylose, cyanoethylated polyvinyl alcohol, cyanoethylated cellulose, cyanoethylated sucrose, amylopectin, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, a copolymer of acrylonitrile - styrene - butadiene, polyvinyl alcohol, polyvinyl ether, polytetrafluoroethylene, polyhexafluoropropylene, a copolymer of styrene - butadiene, or polyvinylidene fluoride.

19. An electronic device, comprising the electrochemical device according to any one of claims 1 to 18.

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