Electrochemical device and its application

Abstract

The present invention provides an electrochemical device and an electronic device using the electrochemical device. The electrochemical device includes an electrode sheet, the electrode sheet including a first current collector, a first electrode sheet protruding from the first current collector, a first active material layer provided on at least one surface of the first current collector, and an insulating layer provided along a side of the first current collector close to the first electrode sheet and adjacent to the first active material layer, the insulating layer including a first region provided on a side close to the first electrode sheet and a second region provided far from the first electrode sheet and adjacent to the first active material layer, the thickness of the insulating layer in the first region being smaller than the thickness of the insulating layer in the second region. The electrochemical device of the present application controls the ratio between the thickness of the insulating layer and the thickness of the first active material layer and the shape of the insulating layer being thinly scraped, improving the uniformity of the force of the electrode sheet during roll pressing.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular, to an electrochemical device and an electrochemical device applying the same.

Background Art

[0002] As the demand for high-energy density batteries increases, generally, in order to realize an improvement in battery capacity, it is necessary to provide an active material layer with a large coating weight on the electrode sheet to improve the battery capacity. However, when the coating weight (thick electrode) is large, generally the thickness of the active material layer becomes large, and there is a relatively obvious thickness step between the insulating layer coated on the electrode sheet edge for burr prevention and the active layer, which affects the appearance of the electrode sheet. Furthermore, the insulating coating slurry fluid is affected by the double effects of the expansion effect due to the excessive stress on the surface of the coating device and the casting phenomenon due to the surface tension of the slurry during the drying process, resulting in a thick edge form at the edge of the insulating coating. The thick edge of the insulating coating causes the occurrence of the drum edge phenomenon during the winding of the electrode sheet, and in severe cases, the electrode sheet may break. At the same time, when the electrode sheet is roll-pressed, the tension distribution of the electrode sheet becomes unbalanced, and the alignment degree fails to meet the requirements, affecting the dimensions of the electrode sheet processing.

[0003] To solve such problems, the prior art makes the coating size of the insulating layer larger than the actual required size of the electrode when manufacturing the electrode, and then cuts off the thick edge region of the electrode sheet edge. However, making the coating size of the insulating coating larger than the actual required size of the electrode may cause excessive waste of materials when there is a thick edge. How to find a solution that can improve the appearance of the electrode sheet of the thick electrode and remove the drum edge phenomenon of the insulating layer, while meeting the demand for high energy density and improving the yield of battery products, is something that those skilled in the art need to consider.

Summary of the Invention

[0004] To solve the problem of the coating of the electrode sheet in the prior art being too thick, the embodiments of the present application provide an electrochemical device, the electrochemical device includes an electrode sheet, the electrode sheet includes a first current collector, and a Tab 1 protruding from the first current collector, and a first active material layer provided on at least one surface of the first current collector, and the Tab 1 an insulating layer provided along the side close to the in the first current collector and adjacent to the first active material layer. The insulating layer includes a first region provided on the side close to the, and a second region provided far from the and adjacent to the first active material layer. The thickness of the insulating layer in the first region is smaller than the thickness of the insulating layer in the second region. Tab 1 near side, Tab 1 and far from the and adjacent to the first active material layer.

[0005] In a possible embodiment, the first region includes a first surface, and the plane where the first surface is located intersects the plane where the first current collector is located to form an acute angle α. The thickness of the second region is H, the width of the insulating layer is W, and W / H≧cotα.

[0006] In a possible embodiment, the range of the acute angle α is 5° to 75°.

[0007] In a possible embodiment, the range of the thickness H of the second region is 20 μm to 100 μm, and the range of the width W of the insulating layer is 1 mm to 10 mm.

[0008] In a possible embodiment, the range of the thickness L of the first active material layer is 30 μm to 200 μm.

[0009] In a possible embodiment, the thickness of the second region is H, and the thickness H of the second region and the thickness L of the first active material layer satisfy the relationship of 0.3≦H / L≦0.8.

[0010] In a possible embodiment, the coating weight of the first active material layer is 0.06 mg / mm 2 ~0.35 mg / mm 2 is.

[0011] In a possible embodiment, the consolidation density of the first active material layer is 2 g / cc to 6 g / cc.

[0012] In a possible embodiment, the insulating layer includes inorganic particles containing at least one of boehmite, alumina, zirconia, boron oxide, or hexagonal boron nitride, and a binder containing at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride - hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate salt, or sodium carboxymethyl cellulose.

[0013] This application further provides an electronic device including the aforementioned electrochemical device.

[0014] Compared with the prior art, in the electrochemical device of this application, outside the first active material layer, an insulating layer having a first region and a second region with different thicknesses is provided. The thickness of the second region closer to the first active material layer is greater than the thickness of the first region farther from the first active material layer. That is, when removing the thick - edge form by thinning the region near the edge of the electrode sheet but controlling so that this thinned region does not extend to the first active material layer, it avoids the loss of the active material in the first active material layer, increases the energy density of the electrochemical device, overcomes the problem of the drum edge of the electrode sheet by removing the thick - edge form, and reduces the thickness difference between the first active material layer and the insulating layer.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0016] Hereinafter, with reference to the drawings, the content of the present application will be described more comprehensively. The drawings show exemplary embodiments of the present application. However, the present application can be implemented in many different forms and should not be construed as being limited to the exemplary embodiments described herein. These exemplary embodiments are provided to make the present application thorough and complete and to fully convey the scope of the present application to those skilled in the art. Like reference numerals represent the same or similar elements.

[0017] The terms used in this specification are only used to describe specific exemplary embodiments and are not intended to limit the present application. As used in this specification, unless the context clearly indicates otherwise, the singular forms "a", "one", and "this" are intended to include the plural forms as well. Further, when used in this specification, "comprising" and / or "including" and / or "having", integers, steps, operations, components and / or components, other than the presence or addition of one or more other features, regions, integers, steps, operations, components, components, and / or groups thereof.

[0018] Unless otherwise specifically defined, all terms (including technical terms and scientific terms) used in this specification have the same meaning as commonly understood by those of ordinary skill in the art to which the present application belongs. Further, terms defined in general dictionaries should be interpreted as having a meaning consistent with the meaning in the relevant technology and the content of the present application, and should not be interpreted as having an idealized or overly formal meaning unless explicitly defined.

[0019] Exemplary embodiments will be described below in connection with the drawings. Note that the components depicted in the drawings are not necessarily shown to scale, while the same or similar components are assigned the same or similar reference numeral expressions or similar technical terms.

[0020] Hereinafter, with reference to the drawings, specific embodiments of the present application will be described in more detail.

[0021] As shown in FIG. 1, one embodiment of the present application provides an electrochemical device 1 including a pole sheet 10. In one embodiment, the electrochemical device 1 of the present application is described by taking a lithium-ion battery as an example, but the electrochemical device 10 of the present application is not limited to a lithium-ion battery.

[0022] FIG. 2 is a partially enlarged schematic diagram of the pole sheet 10 of the electrochemical device 1 according to one embodiment of the present application. As shown in the figure, the pole sheet 10 includes a first current collector 11, a first tab 12, a first active material layer 13, and an insulating layer 14. Here, Tab 1 12 protrudes from the first current collector 11, the first active material layer 13 is provided on at least one surface of the first current collector 11, and the insulating layer 14 is on the Tab 1 side close to 12 and is provided along the side, adjacent to the first active material layer 13. The insulating layer 14 includes a first region 141 provided on the side close to the first tab 12, and a second region 142 provided between the first region 141 and the first active material layer 13 and adjacent to the first region 141 and the first active material layer 13. The thickness of the insulating layer 14 located in the first region 141 is smaller than the thickness of the insulating layer 14 located in the second region 142 in the direction perpendicular to the surface of the first current collector 11 where the insulating layer 14 is provided. In one embodiment, the fact that the thickness of the insulating layer 14 located in the first region 141 is smaller than the thickness of the insulating layer 14 located in the second region 142 means that the thickness of the insulating layer 14 at each position in the first region 141 is smaller than the thickness of the insulating layer 14 located in the second region 142. In other embodiments, the fact that the thickness of the insulating layer 14 located in the first region 141 is smaller than the thickness of the insulating layer 14 located in the second region 142 means that the maximum thickness of the insulating layer 14 located in the first region 141 is smaller than the minimum thickness of the insulating layer 14 located in the second region 142.

[0023] Outside the first active material layer 13, an insulating layer 14 having a first region 141 and a second region 142 with different thicknesses is provided. The thickness of the second region 142 closer to the first active material layer 13 is greater than the thickness of the first region 141 farther from the first active material layer 13. That is, the insulating layer 14 thins the region near the edge of the electrode sheet 10, but controls so that this thinned region does not extend to the first active material layer 13. When removing the thick-edge form, it avoids the loss of the active material in the first active material layer 13, increases the energy density of the electrochemical device 10, then removes the thick-edge form to overcome the problem of the drum edge of the electrode sheet 10, and reduces the thickness difference between the first active material layer 13 and the insulating layer 14.

[0024] In the positive electrode of the embodiment of the present application, there is no particular limitation on the positive electrode as long as the object of the present application can be achieved. For example, the positive electrode usually includes a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector is not particularly limited, but usually includes at least one of an aluminum foil, an aluminum alloy foil, or a composite current collector. The positive electrode active material layer contains a positive electrode active material, and the positive electrode active material is not particularly limited and may include at least one of lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobaltate, lithium manganate, lithium manganese iron phosphate, or lithium titanate.

[0025] In the negative electrode of the embodiment of the present application, there is no particular limitation on the negative electrode as long as the object of the present application can be achieved. For example, the negative electrode usually includes a negative electrode current collector and a negative electrode active material layer. However, the negative electrode current collector is not particularly limited and can include at least one of a copper foil, an aluminum foil, an aluminum alloy foil, and a composite current collector. The negative electrode active material layer contains a negative electrode active material, and the negative electrode active material is not particularly limited and can include at least one of artificial graphite, natural graphite, mesocarbon microbeads, soft carbon, hard carbon, silicon, silicon carbon, lithium titanate, and the like.

[0026] Note that the electrode sheet 10 may be a positive electrode or a negative electrode. In the embodiments of the present application, an example in which the electrode sheet 10 is a positive electrode will be described in the present application. In contrast, the first active material layer 13 may be a positive electrode active material layer or a negative electrode active material layer. In the embodiments of the present application, an example of a positive electrode active material layer will be described in the present application. In one embodiment, the first tab 12 protrudes from the first current collector 11, that is, the first tab 12 protrudes in a direction away from the central region of the first current collector 11 rather than from the edge of the first current collector 11. In the present embodiment, the fact that the first tab 12 protrudes from the first current collector 11 means that the first tab 12 has an integral structure with the first current collector 11 and may be formed by extending from the edge of the first current collector 11. In other embodiments, the first tab 12 has a non-integral structure with the first current collector 11, and the first tab 12 may be connected to the first current collector 11, for example, by welding, before the insulating layer 14 is applied to the electrode sheet 10.

[0027] In one embodiment, the first active material layer 13 is provided on at least one surface of the first current collector 11. For example, the first active material layer 13 may be provided on the surface opposite to the first current collector 11.

[0028] In the present embodiment, the insulating layer 14 is applied to the surface of the first current collector 11 and is adjacent to the first active material layer 13. The insulating layer 14 is provided at the edge of the first current collector 11 and covers at least the cut edge of the first current collector 11, covering the cutting burr located at the edge and avoiding the burr from piercing the separator. Moreover, the insulating layer 14 also covers at least a partial region of the boundary between the first current collector 11 and the first tab 12, covering the cutting burr at one end adjacent to the first current collector 11 in the first tab 12 and avoiding the burr from piercing the separator.

[0029] As shown in FIG. 3, the first region 141 has a first surface 143. The surface on which the first surface 143 is located intersects with the surface on which the first current collector 11 is located to form an acute angle α. The thickness of the second region 142 is H, the width of the insulating layer is W, and W / H≧cotα.

[0030] In one embodiment, the cross-section along the thickness direction of the electrode sheet in the insulating layer 14 is trapezoidal. Specifically, the insulating layer 14 has a thickness substantially equal to that of the side adjacent to the first active material layer 13 (i.e., the second region 142). The insulating layer 14 has a first region 141 on the side away from the first active material layer 13 and close to the first tab 12. The thickness of the insulating layer 14 gradually decreases from the boundary between the first region 141 and the second region 142 toward the first tab 12 side until the first surface 143 intersects the first current collector 11 to form an acute angle α.

[0031] In one embodiment, if W / H < cotα, in the process of cutting the first current collector 11 to obtain the first tab 12, the cross-section along the thickness direction of the electrode sheet of the insulating layer 14 is not substantially trapezoidal but substantially triangular. That is, the portion of the first active material layer 13 close to the insulating layer 14 is removed, resulting in a decrease in the overall energy density of the electrochemical device 1 and energy loss, and there is a possibility that the boundary between the first active material layer 13 and the insulating layer 14 becomes blurred.

[0032] In one embodiment, the range of the acute angle α is 5° to 75°. If the acute angle α is less than 5°, there is a possibility that the insulating layer 14 cannot meet the requirement of this angle during the thinning process. If the acute angle α is greater than 75°, the average thickness of the insulating layer 14 in the first region 141 becomes too large, and there is a possibility that the end of the electrode sheet 10 bulges. In one embodiment, the acute angle α is obtained by acquiring an image of the cross-section of the insulating layer 14 using a CCD camera and measuring the angle in the region corresponding to the acute angle α in the image.

[0033] In one embodiment, the thickness of the insulating layer 14, i.e., the thickness of the second region, can be measured by a micrometer or a CCD camera. For example, a pole sheet 10 of a predetermined unit length is cut or selected, and at least one surface of this pole sheet 10 includes cross-sections of the first region 141 and the second region 142. The second region 142 on the pole sheet 10 is measured multiple times using a micrometer to obtain the thickness of the insulating layer 14. For example, the thickness of the second region 142 is measured 15 times respectively, and then the average value of the multiple measurements is taken as the thickness of the second region 142. Alternatively, using a CCD camera, an image of the surface including the cross-sections of the first region 141 and the second region 142 is captured, and the thickness of the insulating layer 14 is obtained by a measuring instrument (such as software) combined with the CCD camera. Different images or different parts of the same image are repeatedly obtained multiple times (for example, 15 times), and the average value of the multiple measured thicknesses is obtained to obtain the thickness of the insulating layer 14.

[0034] In one embodiment, the width of the insulating layer 14 can be measured by a CCD camera. For example, an image of the insulating layer 14 including the continuous first region 141 and the second region 142 is captured using a CCD camera. Specifically, an image is obtained using a CCD camera in a low magnification state. When the two side edges of the insulating layer 14 are set by a measuring tool (such as software) combined with the CCD camera, the width of the insulating layer 14 can be obtained. Different images or different parts of the same image are repeatedly obtained multiple times (for example, 15 times), and the average value of the multiple measured thicknesses is obtained to obtain the width of the insulating layer 14.

[0035] In one embodiment, the range of the thickness H of the second region 142 is 20 μm to 100 μm, and the range of the width W of the insulating layer 14 is 1 mm to 10 mm. If the thickness H of the second region 142 is less than 20 μm, the thickness of the insulating layer 14 becomes smaller than the length of a general burr, and the burr cannot be effectively covered, and there may be a risk of short circuit in the electrochemical device 1. If the thickness of the second region 142 is greater than 100 μm, the pole sheet 10 may not be able to meet the parameter requirements of cold pressing.

[0036] In one embodiment, the thickness L of the first active material layer 13 ranges from 30 μm to 200 μm. The thickness H of the second region 142 and the thickness L of the first active material layer 13 satisfy the relationship of 0.3 ≦ H / L ≦ 0.8. If this ratio is too small and the insulating layer 14 is too thin, it cannot play the role of preventing burrs. If this ratio is too large and the insulating layer is too thick, it becomes difficult to achieve the consolidation density set in the cold pressing process of the electrode sheet 10.

[0037] In one embodiment, the coating weight of the first active material layer 13 is 0.06 mg / mm 2 ~0.35 mg / mm 2 is.

[0038] In one embodiment, the weight of the first active material layer 13 or the electrode sheet 10 per unit area is measured by a one-ten-thousandth analytical balance, converted into the following formula to obtain the coating weight, coating weight = (electrode sheet weight - current collector weight) / electrode sheet area, and the average value can be taken. If the coating weight is less than 0.06 mg / mm 2 is smaller, the energy density is low and it is difficult to meet the requirements, or problems such as particles and scratches are likely to occur in the first active material layer 13. If the coating weight is greater than 0.35 mg / mm 2 is larger, it is difficult to dry the electrode sheet 10, or processing problems such as cracking may occur. Also, because the corresponding thickness is large, the coating process becomes difficult. On the other hand, the first active layer 13 (for example, an active material made of lithium iron phosphate) is likely to crack, which is disadvantageous for lithium ion diffusion and has an adverse effect on the electrochemical cycle.

[0039] In one embodiment, the consolidation density of the first active material layer 13 is 2 g / cc to 6 g / cc. In one embodiment, the weight of the first active material layer 13 or the electrode sheet 10 per unit area is measured by a one-ten-thousandth analytical balance, and further, the consolidation density may be obtained by an equation such as (the weight of the insulating layer electrode sheet per unit area - the weight of the current collector) / the thickness of the insulating layer other than the base material, and the average value may be obtained. If the consolidation density is too low (less than 2 g / cc), there is less active material per unit volume, so the energy density is low and it becomes difficult to meet the demand. If the consolidation density is too high (greater than 6 g / cc), the porosity of the first active layer 13 is too small, weakening the ion transport ability, the internal resistance (DCR) is too large, or the electrode sheet 10 is embrittled, making it easy to cause band breakage in the cold pressing process.

[0040] In one embodiment, the insulating layer 14 includes inorganic particles containing at least one of boehmite, alumina, zirconia, boron oxide, or hexagonal boron nitride, and a binder containing at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride - hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate salt, or sodium carboxymethyl cellulose.

[0041] The electrochemical device of the present application further includes a separator. The separator separates the positive electrode and the negative electrode, prevents internal short circuit of the electrochemical device, and enables free passage of electrolyte ions, thus playing a role in the electrochemical charge and discharge process. In the present application, the separator is not particularly limited as long as it can achieve the object of the present application. For example, at least one of polyolefin (PO) - based separators mainly composed of polyethylene (PE) and polypropylene (PP), polyester films (such as polyethylene terephthalate (PET) films), cellulose films, polyimide films (PI), polyamide films (PA), spandex or aramid films, woven fabric films, non - woven fabric films (non - woven fabrics), microporous films, composite films, separator papers, laminated films, spun films, etc.

[0042] Furthermore, the separator may have a base material layer and a surface treatment layer. The base material layer may be a nonwoven fabric, a film, or a composite film having a porous structure, and the material of the base material layer may contain at least one of polyethylene, polypropylene, polyethylene terephthalate, polyimide, etc. In one embodiment, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be used. In one embodiment, a surface treatment layer is provided on at least one surface of the base material layer, and the surface treatment layer may be a polymer layer, an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.

[0043] Furthermore, for example, the inorganic layer may contain inorganic particles and a binder. The inorganic particles are not particularly limited, and may be, for example, at least one selected from aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium sulfate, etc. The binder is not particularly limited, and may be, for example, one or a combination of a plurality of types selected from the group consisting of polyvinylidene fluoride, a copolymer of vinylidene fluoride - hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate salt, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene. For example, the polymer layer contains a polymer, and the material of the polymer contains at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate salt, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, poly(vinylidene fluoride - hexafluoropropylene), etc.

[0044] The electrochemical device of the present invention further includes an electrolyte, which may be one or more of a gel electrolyte, a solid electrolyte, and an electrolytic solution. The electrolytic solution contains a lithium salt and a non-aqueous solvent.

[0045] In one embodiment, when the electrochemical device 10 is a lithium-ion battery, the lithium salt is LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , LiSiF 6 , LiBOB, lithium difluoroborate, or one or more selected therefrom. As the lithium salt, since it can provide high ionic conductivity and improve cycle characteristics, LiPF 6 can be used.

[0046] The non-aqueous solvent can be a carbonate compound, a carboxylic acid ester compound, an ether compound, other organic solvents, or a combination thereof.

[0047] The carbonate compound may be a chain carbonate compound, a cyclic carbonate compound, a fluorinated carbonate compound, or a combination thereof.

[0048] Examples of the above-mentioned chain carbonate compounds include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), and combinations thereof. Examples of the cyclic carbonate compounds include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), and combinations thereof. Examples of the fluorinated carbonate compounds include, for example, fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethyl ethylene carbonate, and combinations thereof.

[0049] Examples of the above-mentioned carboxylic acid ester compounds include methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, and combinations thereof.

[0050] Examples of the above-mentioned ether compounds include dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.

[0051] Examples of other organic solvents include dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, phosphate esters, and combinations thereof.

[0052] The manufacturing process of the electrochemical device 1 is well-known to those skilled in the art and is not particularly limited in this application. For example, the electrochemical device can be manufactured by a process in which a positive electrode and a negative electrode are stacked via a separator, and after performing operations such as winding and folding as necessary, they are placed in a housing, and an electrolytic solution is injected into the housing and sealed. The separator used here is the above-mentioned separator provided in this application. Also, if necessary, an overcurrent prevention element, a lead plate, etc. can be placed in the housing to prevent an increase in pressure and overcharge / discharge inside the electrochemical device.

[0053] As shown in FIG. 4, it is a schematic perspective view of the electronic device 100 provided in the embodiment of this application. This application further provides an electronic device 100 including the electrochemical device 1. In FIG. 4, only the electronic device 100 is exemplified by a mobile phone, but in other embodiments, the electronic device 100 of this application is not particularly limited and can be used in any conventionally known electronic device. In some aspects, the electronic device 100 can include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an e-book player, a mobile phone, a portable facsimile, a portable copier, a portable printer, a headset, stereo earphones, a video camera, a liquid crystal TV, a portable cleaner, a portable CD player, a mini disk, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, an emergency power source, a motor, an automobile, a motorcycle, an assist bicycle, a bicycle, a lighting fixture, a toy, a game device, a watch, a power tool, a flash, a camera, a large household battery, a lithium ion capacitor, etc.

[0054] COV test of the thickness of the electrode sheet edge. 1) Remove the electrode sheet from the battery product under the environment of (25±3)°C. Wipe off the electrolyte remaining on the surface of the electrode sheet with dust-free paper. 2) Cut the electrode sheet to obtain an electrode sheet sample with a certain area size. 3) Use a micrometer to measure the thickness of the electrode sheet edge near the tab of the electrode sheet sample in 2), sequentially test the thickness values of 15 different points along the electrode sheet edge, and calculate the COV value of the thickness values of all test points.

[0055] Battery volume energy density test. 1) Under the environment of (25±3)°C, charge the battery at a constant current until 3.6V, and then discharge it to 2.5V at a 0.5C rate to obtain the actual capacity Cap. 2) The discharge stage of the battery is E. 3) Measure the length, width, and height of the battery, measure 10 points for each surface and take the average value, and the volume V = length * width * height. 4) The volume energy density VED = Cap * E / V. Example 1

[0056] <1-2. Preparation of the positive electrode sheet> Lithium cobaltate, acetylene black, and polyvinylidene fluoride (PVDF) as the positive electrode active material were mixed at a mass ratio of 94:3:3, and then N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75% and stirred uniformly. The slurry was uniformly coated on one side of an aluminum foil with a thickness of 12μm, dried at 90°C, and cold-pressed to obtain a positive electrode sheet with a positive electrode active material layer thickness of 100μm. Then, by repeating the above process on the other side of this positive electrode sheet, a positive electrode sheet with the positive electrode active material layer coated on both sides was obtained. Here, the thickness L of the positive electrode active material (the first active material layer) is 100μm, the coating weight of the first active material layer is 0.2mg / mm 2 and the compaction density of the first active material layer is 2.0g / cc.

[0057] An insulating layer is provided at the edge of the positive electrode active material layer on the side close to the tab of the positive electrode sheet. Here, the insulating layer components (mass ratio) are PVDF and boehmite = 40%:60%, the thickness H of the second region of the insulating layer is 20 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0058] The positive electrode sheet is cut into a specification of 74 mm × 867 mm, and the electrode sheets are welded and then used.

[0059] <1-3. Preparation of the negative electrode sheet> Artificial graphite, acetylene black, styrene-butadiene rubber, and sodium carboxymethyl cellulose, which are negative electrode active materials, are mixed at a mass ratio of 96:1:1.5:1.5. Then, deionized water is added as a solvent to prepare a slurry with a solid content of 70%, and it is uniformly stirred. The slurry is uniformly coated on one surface of a copper foil with a thickness of 8 μm, dried at 110°C, and cold-pressed to obtain a negative electrode sheet with a negative electrode active material layer coated on one side with a thickness of 150 μm. Then, the above coating process is repeated on the other surface of this negative electrode sheet to obtain a negative electrode sheet with negative electrode active material layers coated on both sides. The negative electrode sheet is cut into a specification of 74 mm × 867 mm, and the electrode sheets are welded and then used.

[0060] <1-5. Preparation of the electrolyte> Under an environment with a water content of less than 10 ppm, ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), propyl propionate (PP), and vinylene carbonate (VC), which are non-aqueous organic solvents, are mixed at a mass ratio of 20:30:20:28:2. Then, lithium hexafluorophosphate (LiPF 6 ) is added to the non-aqueous organic solvent and uniformly dissolved to obtain an electrolyte. The mass ratio of LiPF 6 to the non-aqueous organic solvent is 8:92.

[0061] <1-6 Fabrication of the lithium-ion battery> The positive electrode sheet and the negative electrode sheet were wound, and a polyethylene (PE) film was used as a separator to separate between the positive electrode sheet and the negative electrode sheet, thereby fabricating an electrode assembly. The electrode assembly was placed in an aluminum plastic film packaging bag, moisture was desorbed at 80 °C, the prepared electrolyte was injected, and a lithium ion battery was obtained through processes such as vacuum sealing, standing, formation, and shaping.

[0062] Example 2 Example 2 has the same lithium ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 and the consolidation density of the first active material layer is 2.0 g / cc, the insulating layer component (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 40 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0063] Example 3 Example 3 has the same lithium ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 and the consolidation density of the first active material layer is 2.0 g / cc, the insulating layer component (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 50 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0064] Example 4 Example 4 has the same lithium ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2wherein the compaction density of the first active material layer is 2.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 80 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0065] Example 5 Example 5 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (first active material layer) is 125 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 wherein the compaction density of the first active material layer is 2.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 100 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0066] Example 6 Example 6 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 wherein the compaction density of the first active material layer is 2.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 50 μm, the width W of the insulating layer is 1 mm, and cotα corresponding to the acute angle α is 1.

[0067] Example 7 Example 7 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 wherein the compaction density of the first active material layer is 2.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 50 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0068] Example 8 Example 8 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 and the consolidation density of the first active material layer is 2.0 g / cc. The insulating layer component (mass ratio) is PVDF: boehmite = 40%: 60%. The thickness H of the second region of the insulating layer is 80 μm, the width W of the insulating layer is 10 mm, and cotα corresponding to the acute angle α is 1.

[0069] Example 9 Example 9 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 and the consolidation density of the first active material layer is 2.0 g / cc. The insulating layer component (mass ratio) is PVDF: boehmite = 40%: 60%. The thickness H of the second region of the insulating layer is 30 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0070] Example 10 Example 10 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 and the consolidation density of the first active material layer is 2.0 g / cc. The insulating layer component (mass ratio) is PVDF: boehmite = 40%: 60%. The thickness H of the second region of the insulating layer is 50 μm, the width W of the insulating layer is 10 mm, and cotα corresponding to the acute angle α is 0.3.

[0071] Example 11 Example 11 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2wherein the consolidation density of the first active material layer is 2.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 80 μm, the width W of the insulating layer is 10 mm, and cotα corresponding to the acute angle α is 1.

[0072] Example 12 Example 12 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 30 μm, and the coating weight of the first active material layer is 0.06 mg / mm 2 wherein the consolidation density of the first active material layer is 2.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 24 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0073] Example 13 Example 13 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 175 μm, and the coating weight of the first active material layer is 0.35 mg / mm 2 wherein the consolidation density of the first active material layer is 2.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 88 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 11.4.

[0074] Example 14 Example 14 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 88 μm, and the coating weight of the first active material layer is 0.35 mg / mm 2 wherein the consolidation density of the first active material layer is 4.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 44 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0075] Example 15 Example 15 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 58 μm, and the coating weight of the first active material layer is 0.35 mg / mm 2 and the compaction density of the first active material layer is 6.0 g / cc. The insulating layer component (mass ratio) is PVDF: boehmite = 40%: 60%. The thickness H of the second region of the insulating layer is 30 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0076] Example 16 Example 16 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 and the compaction density of the first active material layer is 2.0 g / cc. The insulating layer component (mass ratio) is polyacrylic acid: zirconia = 30%: 70%. The thickness H of the second region of the insulating layer is 50 μm, the width W of the insulating layer is 1.2 mm, and cotα corresponding to the acute angle α is 1.

[0077] Example 17 Example 17 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 and the compaction density of the first active material layer is 2.0 g / cc. The insulating layer component (mass ratio) is PVDF: boehmite = 40%: 60%. The thickness H of the second region of the insulating layer is 87.5 μm, the width W of the insulating layer is 1 mm, and cotα corresponding to the acute angle α is 11.4.

[0078] Comparative Example 1 Comparative Example 1 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (the first active material layer) is 30 μm, and the coating weight of the first active material layer is 0.045 mg / mm2 wherein the compaction density of the first active material layer is 1.5 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 30 μm, the width W of the insulating layer is 1 mm, and the insulating layer was not thinly shaved.

[0079] Comparative Example 2 Comparative Example 2 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 wherein the compaction density of the first active material layer is 2.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 50 μm, the width W of the insulating layer is 1.2 mm, and the insulating layer was not thinly shaved.

[0080] Comparative Example 3 Comparative Example 3 has the same lithium-ion battery manufacturing process as Example 1, but there are differences in the composition parameters. Here, the thickness L of the positive electrode active material (first active material layer) is 100 μm, and the coating weight of the first active material layer is 0.2 mg / mm 2 wherein the compaction density of the first active material layer is 2.0 g / cc, the insulating layer composition (mass ratio) is PVDF: boehmite = 40%: 60%, the thickness H of the second region of the insulating layer is 0 μm, the width W of the insulating layer is 1.2 mm, and the insulating layer was not thinly shaved.

[0081] For the above Examples 1 to 17 and Comparative Examples 1 to 3, processes such as winding and cold pressing were performed, the appearance of the electrode sheet was observed, and the energy density was calculated, as shown in Table 1 below.

[0082]

Table 1

[0083] Compared with the prior art, the electrochemical device of the present application provides a first active material layer and an insulating layer adjacent to each other on the electrode sheet. The insulating layer covers the edge burrs of the burrs of the first current collector and the tab, avoiding short circuits in the electrochemical device. By providing a first region thinly shaved outside the insulating layer, the ratio of the thickness of the insulating layer to the thickness of the first active material layer and the shape of the thinly shaved insulating layer are controlled, improving the uniformity of the force during the roll pressing process of the electrode sheet when ensuring the safety performance of the electrochemical device, and further improving the overall performance of the electrochemical device.

[0084] With reference to the drawings described above, specific embodiments of the present application have been described. However, those skilled in the art can understand that various changes and substitutions can be made to the specific embodiments of the present application without departing from the spirit and scope of the present application. These changes and substitutions are within the limited scope of the present application.

Description of Reference Numerals

[0085] 1 Electrochemical device 10 Electrode sheet 11 First current collector 12 First tab 13 First active material layer 14 Insulating layer 141 First region 142 Second region 143 First surface α Acute angle 100 Electronic device

Claims

1. The polar sheet includes: A first current collector; a first tab protruding from the first current collector; a first active material layer provided on at least one surface of the first current collector; an insulating layer provided along a side of the first current collector close to the first tab and adjacent to the first active material layer; the insulating layer includes a first region provided close to the first tab and a second region provided farther from the first tab and adjacent to the first active material layer, The first region is disposed extending from a side of the second region away from the first tab, a thickness of the insulating layer in the first region is smaller than a thickness of the insulating layer in the second region; the first region includes a first surface, a plane in which the first surface lies intersects with a plane in which the first current collector lies to form an acute angle α, the acute angle α being in the range of 5° to 75°; an electrochemical device, wherein the second region has a thickness H, and the thickness H of the second region and the thickness L of the first active material layer satisfy the relationship 0.3≦H / L≦0.

8.

2. The electrochemical device described in Claim 1, characterized in that the width of the insulating layer is W and W / H≧cotα.

3. 2. The electrochemical device according to claim 1, wherein the thickness H of the second region is in the range of 20 μm to 100 μm, and the width W of the insulating layer is in the range of 1 mm to 10 mm.

4. 2. The electrochemical device according to claim 1, wherein the thickness L of the first active material layer is in the range of 30 μm to 200 μm.

5. The coating weight of the first active material layer is 0.06 mg / mm ２ ~0.35mg / mm ２ 2. The electrochemical device according to claim 1 .

6. 2. The electrochemical device according to claim 1, wherein the first active material layer has a compaction density of 2 g / cc to 6 g / cc.

7. The electrochemical device according to claim 1, characterized in that the insulating layer contains inorganic particles containing at least one of boehmite, alumina, zirconia, boron oxide, and hexagonal boron nitride, and a binder containing at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, and sodium carboxymethylcellulose.

8. An electronic device comprising the electrochemical device according to any one of claims 1 to 7.

Images