Electrochemical device and application thereof

Abstract

To provide an electrochemical device and an electronic device using the electrochemical device.SOLUTION: An electrochemical device includes an electrode sheet 10, the electrode sheet 10 includes a first current collector 11, a first electrode sheet protruding from the first current collector 11, a first active material layer 13 provided on at least one surface of the first current collector 11, and an insulating layer 14 provided along a side of the first current collector 11 closer to the first electrode sheet and adjacent to the first active material layer 13, the insulating layer 14 includes a first region 141 provided on a side closer to the first electrode sheet and a second region 142 provided farther from the first electrode sheet and adjacent to the first active material layer 13, the thickness of the insulating layer 14 in the first region 141 is smaller than the thickness of the insulating layer 14 in the second region 142. The electrochemical device according to the present application controls the ratio between the thickness of the insulating layer 14 and the thickness of the first active material layer 13 and the shape of the insulating layer 14 scraped thinly, thereby improving the uniformity of the force on the electrode sheet 10 during roll pressing.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present application relates to the field of battery technology, and more particularly to an electrochemical device and an electrochemical device to which the same is applied. [Background technology]

[0002] As demand for high-energy density batteries increases, it is generally necessary to apply a heavy coating of active material to the electrode sheet to improve battery capacity. However, a heavy coating (thick electrode) generally results in a thick active material layer, which results in a relatively obvious thickness difference between the insulating layer coated on the edge of the electrode sheet to prevent burrs and the active layer, affecting the appearance of the electrode sheet. Furthermore, the insulating coating slurry fluid causes a thick edge at the edge of the insulating coating due to the dual effects of the expansion effect caused by excess stress on the coating device surface and the flow phenomenon caused by the surface tension of the slurry during the drying process. The thick insulating coating can lead to the drum edge phenomenon during winding of the electrode sheet, which in severe cases can cause the electrode sheet to break. At the same time, when the electrode sheet is roll-pressed, the tension distribution of the electrode sheet becomes uneven, resulting in alignment that does not meet requirements and affecting the dimensions of the electrode sheet processing.

[0003] To solve this problem, the prior art involves applying an insulating layer larger than the actual size required for the electrode when fabricating the electrode, and then trimming off the thick edge area of the electrode sheet. However, applying an insulating coating larger than the actual size required for the electrode and the presence of thick edges can result in excessive material waste. Those skilled in the art need to consider how to improve the appearance of the electrode sheet for thick electrodes and eliminate the drum edge phenomenon of the insulating layer, thereby meeting the demand for high energy density and increasing the yield of battery products. Summary of the Invention

[0004] In order to solve the problem of the electrode sheet being too thick in the prior art, an embodiment of the present application provides an electrochemical device, the electrochemical device comprising an electrode sheet, the electrode sheet comprising: 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 edge of the first current collector closer to the first electrode sheet and adjacent to the first active material layer, the insulating layer including a first region provided closer to the first electrode sheet and a second region provided farther 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.

[0005] In a possible embodiment, the first region comprises a first surface, a plane in which the first surface lies intersects with a plane in which the first current collector lies at 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 acute angle α is in the range of 5° to 75°.

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

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

[0009] In one 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 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 ~0.35mg / mm 2 is.

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

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

[0013] The present application further provides an electronic device including the electrochemical device described above.

[0014] Compared to the prior art, in the electrochemical device of the present application, an insulating layer having first and second regions with different thicknesses is provided on the outside of the first active material layer, and 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. In other words, the insulating layer thins the region close to the edge of the electrode sheet, but this thinning region is controlled so that it does not extend to the first active material layer. When removing the thick side shape, loss of active material in the first active material layer is avoided, and the energy density of the electrochemical device is increased, and the thick side shape is removed, overcoming the problem of the drum edge of the electrode sheet and reducing the thickness difference between the first active material layer and the insulating layer. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic plan view of an electrochemical device according to an example of the present application. [Figure 2] FIG. 2 is a schematic plan view of an electrode sheet of an electrochemical device according to an example of the present application. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] 1 is a schematic perspective view of an electronic device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0016] The present application will now be described more comprehensively with reference to the drawings. The drawings illustrate exemplary embodiments of the present application. However, the present application may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided so that this application will be thorough and complete, and will 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 herein are used only to describe particular exemplary embodiments and are not intended to limit the present application. As used herein, the singular forms "a," "an," and "it" are intended to include the plural forms unless the context clearly dictates otherwise. Furthermore, as used herein, "comprises" and / or "comprises" and / or "has" integers, steps, operations, components, and / or components, exclusive of the presence or addition of one or more other features, regions, integers, steps, operations, components, components, and / or groups thereof.

[0018] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Furthermore, terms as defined in common dictionaries should be interpreted to have a meaning consistent with the meaning in the relevant art and the context of this application, and are not explicitly defined unless they are interpreted as idealized or overly formal.

[0019] Exemplary embodiments are described below with reference to the drawings, in which it is noted that components depicted in the drawings are not necessarily drawn to scale, while identical or similar components are given identical or similar symbolic designations or similar technical terms.

[0020] Specific embodiments of the present invention will be described in more detail below with reference to the drawings.

[0021] As shown in Figure 1, one embodiment of the present application provides an electrochemical device 1 including an electrode sheet 10. In one embodiment, the electrochemical device 1 of the present application is described using 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] 2 is a partially enlarged schematic diagram of an electrode sheet 10 of an electrochemical device 1 according to one example of the present application. As shown in the figure, the electrode sheet 10 includes a first current collector 11, a first tab 12, a first active material layer 13, and an insulating layer 14. Here, the first tab 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 provided along the side of the first current collector 11 closer to the first tab 12 and adjacent to the first active material layer 13. The insulating layer 14 includes a first region 141 provided on the side closer 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 a direction perpendicular to the surface of the first current collector 11 on which 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 located 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 another 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 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] An insulating layer 14 having a first region 141 and a second region 142 of different thicknesses is provided on the outside of the first active material layer 13, and 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. In other words, the insulating layer 14 thins the region close to the edge of the electrode sheet 10, but this thinning region is controlled so that it does not extend to the first active material layer 13. When removing the thick side shape, loss of active material in the first active material layer 13 is avoided, and the energy density of the electrochemical device 10 is increased. Furthermore, the thick side shape is removed, overcoming the problem of the drum edge of the electrode sheet 10, and reducing the thickness difference between the first active material layer 13 and the insulating layer 14.

[0024] In the positive electrode of the present invention, there are no particular limitations on the positive electrode, as long as the objective of the present invention can be achieved. For example, the positive electrode typically includes a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector is not particularly limited, but typically includes at least one of aluminum foil, aluminum alloy foil, or a composite current collector. The positive electrode active material layer includes a positive electrode active material, which is not particularly limited, and may include at least one of nickel-cobalt manganese oxide, nickel-cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide, lithium manganese oxide, lithium manganese iron phosphate, or lithium titanate.

[0025] In the negative electrode of the present invention, there are no particular limitations on the negative electrode, as long as the object of the present invention can be achieved. For example, the negative electrode typically 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 copper foil, aluminum foil, aluminum alloy foil, and composite current collector. The negative electrode active material layer includes a negative electrode active material, which 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] The electrode sheet 10 may be a positive electrode or a negative electrode, and in the present embodiment, an example in which the electrode sheet 10 is a positive electrode will be described. In contrast, the first active material layer 13 may be a positive electrode active material layer or a negative electrode active material layer, and in the present embodiment, an example in which the electrode sheet 10 is a positive electrode active material layer will be described. In one embodiment, the first tab 12 protrudes from the first current collector 11, i.e., the first tab 12 protrudes in a direction away from the center region of the first current collector 11 beyond the edge of the first current collector 11. In this embodiment, the first tab 12 protruding from the first current collector 11 may be formed as an integral structure with the first current collector 11 and extending from the edge of the first current collector 11. In another embodiment, the first tab 12 may be a non-integral structure with the first current collector 11 and connected to the first current collector 11 by, for example, 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, and for example, the first active material layer 13 may be provided on the opposite surface of the first current collector 11.

[0028] In this 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 on the edge of the first current collector 11 and covers at least the edge of the first current collector 11 after cutting, covering any cutting burrs located on the edge and preventing the burrs from piercing the separator. The insulating layer 14 also covers at least a portion of the boundary between the first current collector 11 and the first tab 12, covering any cutting burrs at one end of the first tab 12 adjacent to the first current collector 11 and preventing the burrs from piercing the separator.

[0029] As shown in FIG. 3, the first region 141 has a first surface 143, and the plane on which the first surface 143 is located intersects with the plane 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 towards 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 in 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 using a ruler or a CCD camera. For example, a predetermined length of the polar sheet 10 is cut or selected, and at least one surface of the polar sheet 10 includes cross sections of the first region 141 and the second region 142. The second region 142 on the polar sheet 10 is measured multiple times using a ruler to determine the thickness of the insulating layer 14. For example, the thickness of each second region 142 is measured 15 times, and the average of the multiple measurements is then used as the thickness of the second region 142. Alternatively, a CCD camera is used to capture an image of the surface including the cross sections of the first region 141 and the second region 142, and the thickness of the insulating layer 14 is obtained using a measuring tool (e.g., software) coupled to the CCD camera. Different images or different portions of the same image can be repeatedly captured multiple times (e.g., 15 times), and the average of the multiple thickness measurements is then used to obtain the thickness of the insulating layer 14.

[0034] In one embodiment, the width of the insulating layer 14 can be measured using a CCD camera. For example, an image of the insulating layer 14 including the continuous first region 141 and second region 142 is captured using a CCD camera. Specifically, the image is captured using a CCD camera at a low magnification, and the width of the insulating layer 14 can be obtained by setting both side edges of the insulating layer 14 using a measurement tool (e.g., software) matched to the CCD camera. Different images or the same image of different locations can be captured multiple times (e.g., 15 times), and the average of the thicknesses measured multiple times can be calculated to obtain the width of the insulating layer 14.

[0035] In one embodiment, the thickness H of the second region 142 is in the range of 20 μm to 100 μm, and the width W of the insulating layer 14 is in the range of 1 mm to 10 mm. If the thickness H of the second region 142 is smaller than 20 μm, the thickness of the insulating layer 14 will be smaller than the length of a typical burr, and the burr will not be covered effectively, which may pose a risk of short circuiting in the electrochemical device 1. If the thickness H of the second region 142 is larger than 100 μm, the electrode sheet 10 may not be able to meet the cold pressing parameter requirements.

[0036] In one embodiment, the thickness L of the first active material layer 13 is in the range of 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 0.3≦H / L≦0.8. If this ratio is too small and the insulating layer 14 is too thin, it will not be able to prevent burrs, and if this ratio is too large and the insulating layer is too thick, it will be difficult to achieve the set compaction density 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 ~0.35mg / mm 2 is.

[0038] In one embodiment, the weight of the first active material layer 13 or electrode sheet 10 per unit area is measured using a 1 / 10,000 analytical balance and converted into the following formula to obtain the weight of the coating: Weight of coating = (weight of electrode sheet - weight of current collector) / area of electrode sheet, and the average value can be calculated. 2 If it is smaller, the energy density is low and it is difficult to meet the requirements, problems such as particles and scratches tend to occur in the first active material layer 13, and the coating weight is 0.35 mg / mm 2 If the thickness is larger, the electrode sheet 10 may have processing problems such as difficulty in drying or cracking during heating. In addition, the corresponding thickness is large, which makes the coating process difficult, and the first active layer 13 (e.g., the active material made of lithium iron phosphate) is prone to cracking, which is unfavorable for the diffusion of lithium ions and has a negative impact on the electrochemical cycle.

[0039] In one embodiment, the compaction 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 may be measured using a 1 / 10,000 analytical balance, and the compaction density may be calculated using the formula (weight of the insulating layer / electrode sheet per unit area - weight of the current collector) / thickness of the insulating layer other than the substrate, and then averaged. If the compaction density is too low (less than 2 g / cc), the amount of active material per unit volume is small, resulting in a low energy density that is difficult to meet demand. If the compaction density is too high (greater than 6 g / cc), the porosity of the first active layer 13 may be too low, weakening the ion transport capacity, increasing the internal resistance (DCR), or embrittling the electrode sheet 10, making it prone to band breakage during the cold pressing process.

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

[0041] The electrochemical device of the present application further includes a separator, which separates the positive and negative electrodes, prevents internal short circuits in the electrochemical device, and allows free passage of electrolyte ions, thereby fulfilling the role of the electrochemical charge and discharge process. The separator used herein is not particularly limited as long as it can achieve the objectives of the present application. Examples of the separator include at least one of polyolefin (PO) separators, primarily polyethylene (PE) or polypropylene (PP), polyester films (e.g., polyethylene terephthalate (PET) films), cellulose films, polyimide films (PI), polyamide films (PA), spandex or aramid membranes, woven membranes, nonwoven membranes (nonwoven fabrics), microporous films, composite films, separator paper, laminate films, and spun films.

[0042] Furthermore, the separator may have a substrate layer and a surface treatment layer. The substrate layer may be a nonwoven fabric, film, or composite film having a porous structure, and the material of the substrate layer may include 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 may be used. In one embodiment, a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or may be a layer formed by mixing a polymer and an inorganic material.

[0043] Furthermore, for example, the inorganic layer may contain inorganic particles and a binder, and the inorganic particles are not particularly limited, but may be 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 two or more selected from the group consisting of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene. For example, the polymer layer includes a polymer, and the polymer material includes at least one of polyamide, polyacrylonitrile, acrylic ester polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, poly(vinylidene fluoride-hexafluoropropylene), and the like.

[0044] The electrochemical device of the present invention further comprises an electrolyte, which may be one or more of a gel electrolyte, a solid electrolyte, and an electrolytic solution, the electrolytic solution including 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 one or more selected from LiPF, LiBF, LiAsF, LiClO, LiB(C H ), LiCH SO, LiCF SO, LiN(SO CF), LiC(SO CF), LiSiF, LiBOB, and lithium difluoroborate. LiPF can be used as the lithium salt because it provides high ionic conductivity and can improve cycle characteristics.

[0046] The non-aqueous solvent may 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 chain carbonate compound 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 compound include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), and combinations thereof. Examples of fluorinated carbonate compounds include 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, trifluoromethylethylene carbonate, and combinations thereof.

[0049] Examples of the carboxylic acid ester compound 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] The 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 the present application. For example, the electrochemical device can be manufactured by a process in which a positive electrode and a negative electrode are stacked together with a separator interposed therebetween, and then, after performing operations such as winding and folding as necessary, the stack is placed in a housing, an electrolyte is poured into the housing, and the housing is sealed. The separator used here is the separator provided in the present application. Furthermore, if necessary, an overcurrent protection element, a lead plate, or the like may be placed in the housing to prevent pressure buildup and overcharging and discharging within the electrochemical device.

[0053] As shown in FIG. 4, a schematic perspective view of an electronic device 100 provided in an embodiment of the present application is shown. The present application further provides an electronic device 100 including an electrochemical device 1. In FIG. 4, the electronic device 100 is illustrated as a mobile phone, but in other embodiments, the electronic device 100 of the present application is not particularly limited and may be used in any conventional electronic device. In some embodiments, the electronic device 100 may include, but is not limited to, a notebook computer, a pen-input computer, a mobile personal computer, an e-book player, a mobile phone, a portable facsimile machine, a portable copier, a portable printer, a headset / stereo / earphone, a video camera, an LCD television, a portable vacuum cleaner, a portable CD player, a minidisc player, a walkie-talkie, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power source, a motor, an automobile, a motorcycle, an electric bicycle, a bicycle, a lighting fixture, a toy, a game device, a watch, a power tool, a flash, a camera, a large household storage battery, a lithium-ion capacitor, and the like.

[0054] COV test of polar sheet edge thickness. 1) Remove the electrode sheet from the battery product in an environment of (25±3)°C. Wipe off any remaining electrolyte on the surface of the electrode sheet with dust-free paper. 2) The polar sheet is cut to obtain a polar sheet sample of a certain area. 3) Using a ruler, measure the thickness of the polar sheet edge of the polar sheet sample in 2) closest to the tab, test the thickness values of 15 different points along the polar sheet edge in sequence, and calculate the COV values of the thickness values of all test points.

[0055] Battery volumetric energy density testing. 1) In an environment of (25±3)°C, charge the battery with a constant current up to 3.6V, then discharge it at a rate of 0.5C down to 2.5V 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, measuring 10 points on each side and taking the average value. Volume V = length * width * height. 4) Volumetric energy density VED=Cap*E / V. Example 1

[0056] <1-2. Preparation of positive electrode sheet> The positive electrode active materials, lithium cobalt oxide, acetylene black, and polyvinylidene fluoride (PVDF), were mixed in 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%. The slurry was then uniformly mixed. One side of a 12-μm-thick aluminum foil was coated with the slurry, dried at 90°C, and cold-pressed to obtain a positive electrode sheet with a positive electrode active material layer thickness of 100 μm. The above process was then repeated on the other side of this positive electrode sheet to obtain a positive electrode sheet coated with a positive electrode active material layer on both sides. Here, the thickness L of the positive electrode active material (first active material layer) was 100 μm, and the coating weight of the first active material layer was 0.2 mg / mm. 2 The first active material layer has a compaction density of 2.0 g / cc.

[0057] An insulating layer is provided on the edge of the positive electrode active material layer on the side closer to the tab of this positive electrode sheet, where 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 to the specifications of 74 mm x 867 mm and the electrode sheet is welded before use.

[0059] <1-3. Preparation of negative electrode sheet> The negative electrode active materials, artificial graphite, acetylene black, styrene butadiene rubber, and sodium carboxymethyl cellulose, were mixed in a mass ratio of 96:1:1.5:1.5, and then deionized water was added as a solvent to prepare a slurry with a solids content of 70%. The mixture was then stirred uniformly. The slurry was evenly applied to one surface of an 8 μm-thick copper foil, dried at 110°C, and cold-pressed to obtain a negative electrode sheet with a 150 μm-thick negative electrode active material layer coated on one side. The above application process was then repeated on the other surface of this negative electrode sheet to obtain a negative electrode sheet with a negative electrode active material layer coated on both sides. The negative electrode sheet was cut to a size of 74 mm x 867 mm, welded, and then used.

[0060] <1-5. Preparation of electrolyte> In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), propyl propionate (PP), and vinylene carbonate (VC) were mixed in a mass ratio of 20:30:20:28:2, and then lithium hexafluorophosphate (LiPF6) was added to the non-aqueous organic solvent and dissolved uniformly to obtain an electrolyte solution, with a mass ratio of LiPF6 to the non-aqueous organic solvent of 8:92.

[0061] <1-6 Fabrication of Lithium-ion Battery> The positive electrode sheet and the negative electrode sheet were wound together and separated by a polyethylene (PE) film as a separator to prepare an electrode assembly. The electrode assembly was placed in an aluminum plastic film packaging bag, dehydrated at 80°C, and the prepared electrolyte was poured into it. The lithium-ion battery was then obtained through processes such as vacuum sealing, standing, chemical conversion, and shaping.

[0062] Example 2 Example 2 has the same lithium ion battery manufacturing flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 2The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 2The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where the thickness L of the positive electrode active material (first active material layer) is 30 μm and the coating weight of the first active material layer is 0.06 mg / mm 2 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where the thickness L of the positive electrode active material (first active material layer) is 175 μm and the coating weight of the first active material layer is 0.35 mg / mm 2 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where the thickness L of the positive electrode active material (first active material layer) is 88 μm and the coating weight of the first active material layer is 0.35 mg / mm 2 The compaction density of the first active material layer is 4.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where the thickness L of the positive electrode active material (first active material layer) is 58 μm and the coating weight of the first active material layer is 0.35 mg / mm 2 The compaction density of the first active material layer is 6.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer is 2.0 g / cc, the insulating layer components (mass ratio) are 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 flow as Example 1, but there are differences in the composition parameters, where the thickness L of the positive electrode active material (first active material layer) is 30 μm and the coating weight of the first active material layer is 0.045 mg / mm2 The compaction density of the first active material layer was 1.5 g / cc, the insulating layer components (mass ratio) were PVDF:boehmite=40%:60%, the thickness H of the second region of the insulating layer was 30 μm, the width W of the insulating layer was 1 mm, and the insulating layer was not thinned.

[0079] Comparative Example 2 Comparative Example 2 has the same lithium ion battery manufacturing flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer was 2.0 g / cc, the insulating layer components (mass ratio) were PVDF:boehmite=40%:60%, the thickness H of the second region of the insulating layer was 50 μm, the width W of the insulating layer was 1.2 mm, and the insulating layer was not thinned.

[0080] Comparative Example 3 Comparative Example 3 has the same lithium ion battery manufacturing flow as Example 1, but there are differences in the composition parameters, where 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 The compaction density of the first active material layer was 2.0 g / cc, the insulating layer components (mass ratio) were PVDF:boehmite=40%:60%, the thickness H of the second region of the insulating layer was 0 μm, the width W of the insulating layer was 1.2 mm, and the insulating layer was not thinned.

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

[0082] [Table 1] JPEG2025118799000003.jpg204170

[0083] Compared to the prior art, the electrochemical device of the present application has a first active material layer and an insulating layer adjacent to each other on the electrode sheet, so that the insulating layer covers the edge burrs of the first current collector and the tab burrs, thereby preventing short circuits in the electrochemical device. Furthermore, by providing a first thin-scraped region on the outside of the insulating layer, the ratio between the thickness of the insulating layer and the thickness of the first active material layer and the shape of the thin-scraped insulating layer can be controlled, ensuring the safety performance of the electrochemical device. This improves the uniformity of the force during the roll pressing process of the electrode sheet, and further improves the overall performance of the electrochemical device.

[0084] Although specific embodiments of the present application have been described with reference to the above-mentioned drawings, those skilled in the art will appreciate that various modifications and substitutions may be made to the specific embodiments of the present application without departing from the spirit and scope of the present application. These modifications and substitutions are within the limited scope of the present application. [Explanation of symbols]

[0085] 1. Electrochemical equipment 10-pole sheet 11 First current collector 12 Tab 1 13 First active material layer 14 Insulating layer 141 First area 142 Second area 143 Page 1 α acute angle 100 Electronic equipment

Claims

1. a polar sheet, the polar sheet comprising: 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 and a second region; a thickness of the insulating layer in the first region is smaller than a thickness of the insulating layer in the second region; The coating weight of the first active material layer is 0.06 mg / mm ２ ~0.35mg / mm ２ An electrochemical device characterized by:

2. the first region includes a first surface; a plane on which the first surface lies intersects with a plane on which the first current collector lies to form an acute angle α; 2. The electrochemical device according to claim 1, wherein the thickness of the second region is H, the width of the insulating layer is W, and W / H≧cotα.

3. 3. The electrochemical device according to claim 2, wherein the acute angle α is in the range of 5° to 75°.

4. 3. The electrochemical device according to claim 2, 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.

5. 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.

6. 2. The electrochemical device according to claim 1, 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.

7. 2. The electrochemical device according to claim 1, wherein the first region is provided on a side closer to the first tab, the second region is provided farther from the first tab and adjacent to the first active material layer, and the first region is installed by extending from the side of the second region farther from the first tab.

8. 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.

9. 2. The electrochemical device according to claim 1, wherein 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.

10. An electronic device comprising the electrochemical device according to any one of claims 1 to 9.

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