Electrochemical device and electronic device

Abstract

An electrochemical device and an electronic device. The electrochemical device comprises an insulating layer, a positive electrode sheet, a negative electrode sheet and a separator provided between the positive electrode sheet and the negative electrode sheet, the insulating layer comprising a porous substrate, the porous substrate comprising polypropylene, and the surface density of the porous substrate being 2 g / m2 to 11 g / m2. The described arrangements enable the electrochemical device to have a high capacity.

Description

An electrochemical device and an electronic device

[0001] This application claims priority to the Chinese patent application No. 202410383464.9, filed on March 31, 2024, and entitled "An electrochemical device and an electronic device", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of electrochemistry, in particular to an electrochemical device and an electronic device. BACKGROUND

[0003] The electrochemical device (such as a lithium ion battery) has the advantages of high energy density, long cycle life, low self-discharge rate and environmental protection, and has been widely used in the fields of aviation, aerospace, navigation, electric vehicles, etc. The lithium ion battery is composed of positive electrode sheet, negative electrode sheet, separator, adhesive tape and other components. In the existing lithium ion battery, the adhesive tape cannot play the capacity in the pasted area, resulting in a loss of capacity of the lithium ion battery. SUMMARY

[0004] The purpose of the present application is to provide an electrochemical device and an electronic device to improve the capacity of the electrochemical device.

[0005] It should be noted that the present application is explained by taking a lithium ion battery as an example in the summary of the application, but the electrochemical device of the present application is not limited to a lithium ion battery. The specific technical solutions are as follows:

[0006] The first aspect of the present application provides an electrochemical device, which comprises an insulating layer, a positive electrode sheet, a negative electrode sheet and a separator arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprises a positive electrode tab, the insulating layer is arranged between the separator and the positive electrode tab, or the insulating layer is arranged between the separator and the end area of the positive electrode sheet; the insulating layer comprises a porous substrate, the porous substrate comprises polypropylene, and the areal density of the porous substrate is 2 g / m 2 to 11 g / m 2 The present application selects a porous substrate comprising polypropylene, and controls the areal density of the porous substrate within the above range, so that the insulating layer has good ion conduction function. In the area covered by the insulating layer in the positive electrode sheet and the negative electrode sheet, lithium ions can shuttle freely and quickly like the area without adhesive tape, so that the capacity of the positive and negative active materials in the covered area can be fully utilized. In this way, the effective area of the positive and negative active material layers is increased, and the capacity of the electrochemical device is improved.

[0007] In some embodiments of the present application, the areal density of the porous substrate is 3 g / m 2 to 11 g / m 2The short circuit risk is reduced while the capacity of the electrochemical device is improved, and the safety performance of the electrochemical device is further improved.

[0008] In some embodiments of the present application, a surface of the porous substrate is provided with a glue layer, and the glue layer comprises a high polymer and inorganic particles; the glass transition temperature of the high polymer is -30℃ to -10℃, the high polymer comprises polyacrylate; the inorganic particles comprise at least one of boehmite, aluminum oxide, titanium dioxide, magnesium oxide, zirconium oxide or zinc oxide; the mass percentage of the high polymer in the glue layer is 30% to 95%, and the mass percentage of the inorganic particles in the glue layer is 5% to 70%. The high polymer of the above type and within the above range of glass transition temperature is selected, the inorganic particles of the above type are selected, and the mass percentage of the high polymer and the inorganic particles in the glue layer is controlled within the above range. The fluid properties such as the viscosity and cohesion of the slurry are adjusted, so that the glue layer shrinks on the surface of the release film to form holes, and the porous substrate is exposed, so that the electrochemical device has a higher capacity without affecting the safety performance.

[0009] In some embodiments of the present application, the glue layer has holes, and part of the porous substrate is exposed from the holes of the glue layer, so that the ion-conducting function of the insulation layer is further improved, and the capacity of the electrochemical device is improved.

[0010] In some embodiments of the present application, the longitudinal tensile strength of the porous substrate is 1000kgf / cm 2 to 2000kgf / cm 2 , and the transverse tensile strength of the porous substrate is 300kgf / cm 2 to 600kgf / cm 2 . The probability of deformation of the insulation layer along the transverse and longitudinal directions of the porous substrate is low, the risk of exposure of the area covered by the insulation layer due to deformation of the insulation layer is reduced, and the electrochemical device has a higher safety performance on the basis of a higher capacity.

[0011] In some embodiments of the present application, the thickness of the insulation layer is 8μm to 30μm, so that the possibility of the burr on the positive electrode plate of the electrochemical device contacting the negative electrode plate through the insulation layer or the burr on the negative electrode plate contacting the positive electrode plate through the insulation layer is reduced.

[0012] In some embodiments of the present application, the thickness of the insulation layer is 8μm to 17μm. The electrochemical device has a higher safety performance and energy density on the basis of a higher capacity.

[0013] In some embodiments of the present application, the thickness of the porous substrate is 8 μm to 20 μm. By regulating the thickness of the porous substrate within the above range, the electrochemical device has a higher volume energy density on the basis of good safety performance.

[0014] In some embodiments of the present application, the melting temperature of the porous substrate is 165 °C to 175 °C. By regulating the melting temperature of the porous substrate within the above range, the electrochemical device has a higher safety performance on the basis of higher capacity.

[0015] In some embodiments of the present application, the Dv50 of the inorganic particles is 80 nm to 1000 nm. By regulating the Dv50 of the inorganic particles within the above range, the electrochemical device has a higher capacity and good safety performance.

[0016] In some embodiments of the present application, the positive electrode tab includes a positive current collector, a positive active material layer, the positive current collector includes opposite first and second surfaces, the positive active material layer is disposed on at least the first surface of the positive current collector, the positive active material layer is provided with a first groove exposing the positive current collector, a positive tab is disposed in the first groove and connected with the positive current collector, and the second surface includes a first empty foil area opposite the first groove; an insulating layer is attached to at least one of the surface of the positive tab, the first empty foil area, the surface of the negative electrode tab adjacent to the first groove, the surface of the negative electrode tab adjacent to the first empty foil area, or the end area of the positive electrode tab. By attaching the insulating layer to the above positions, the electrochemical device has a higher energy density and good safety performance.

[0017] In some embodiments of the present application, the negative electrode tab includes a negative current collector, a negative active material layer, and a negative tab, the negative current collector includes opposite third and fourth surfaces, the negative active material layer is disposed on at least the third surface of the negative current collector, the negative active material layer is provided with a second groove exposing the negative current collector, the negative tab is disposed in the second groove and connected with the negative current collector, and the fourth surface includes a second empty foil area opposite the second groove; an insulating layer is attached to at least one of the surface of the negative tab or the second empty foil area. By attaching the insulating layer to the above positions, the electrochemical device has a higher energy density and good safety performance.

[0018] The second aspect of the present application provides an electronic device, which includes the electrochemical device of any one of the preceding embodiments. Therefore, the electronic device has good use performance.

[0019] The beneficial effects of the present application are as follows:

[0020] The application provides an electrochemical device and an electronic device. The electrochemical device has a porous substrate comprising polypropylene, and the area density of the porous substrate is controlled within a range, so that the insulating layer has good ion conducting function. In the area covered by the insulating layer in the positive electrode tab and the negative electrode tab, lithium ions can shuttle freely and quickly like the area without adhesive paper, so that the capacity of the positive and negative active materials in the covered area can be fully utilized. In this way, the effective area of the positive and negative active material layers is increased, and the capacity of the electrochemical device is improved.

[0021] Of course, implementing any product or method of the present application does not necessarily require achieving all the advantages described above at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other embodiments can also be obtained by those skilled in the art based on these drawings.

[0023] Fig. 1 is a schematic diagram of the cross-sectional structure of the insulating layer along the thickness direction and the longitudinal direction of some embodiments of the present application;

[0024] Fig. 2 is a schematic diagram of the cross-sectional structure of the insulating layer along the thickness direction and the longitudinal direction of some other embodiments of the present application;

[0025] Fig. 3 is a schematic diagram of the positive electrode tab pasting the insulating layer in some embodiments of the present application;

[0026] Fig. 4 is a topographic map of the surface of the insulating layer under a scanning electron microscope (SEM) in some embodiments of the present application;

[0027] Fig. 5 is an enlarged view of Fig. 4;

[0028] Fig. 6 is an enlarged view of Fig. 4;

[0029] Fig. 7 is a schematic diagram of the position of the insulating layer in some embodiments of the present application;

[0030] Fig. 8 is a schematic diagram of the position of the insulating layer in some other embodiments of the present application.

[0031] Reference numerals: 10-positive electrode tab; 11-positive electrode current collector; 12-positive electrode active material layer; 13-positive electrode tab; 11a-first surface; 11b-second surface; 15-first groove; 16-first empty foil area; 20-negative electrode tab; 21-negative electrode current collector; 22-negative electrode active material layer; 23-negative electrode tab; 25-second groove; 26-second empty foil area; 21c-third surface; 21d-fourth surface; 30-separator; 40-insulating layer; 41-porous base material; 42-adhesive layer; 50-non-conductive and non-ionic insulating layer. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. All other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0033] It should be noted that in the specific embodiments of the present application, the present application is explained by taking lithium ion batteries as examples of electrochemical devices, but the electrochemical devices of the present application are not limited to lithium ion batteries.

[0034] The first aspect of the present application provides an electrochemical device, the electrochemical device comprising an insulating layer, a positive electrode tab, a negative electrode tab, and a separator disposed between the positive electrode tab and the negative electrode tab, the positive electrode tab comprising a positive electrode tab, the insulating layer being interposed between the separator and the positive electrode tab, or the insulating layer being interposed between the separator and the end area of the positive electrode tab; the insulating layer comprising a porous base material, the porous base material comprising polypropylene, the areal density of the porous base material being 2 g / m 2 to 11 g / m 2 .

[0035] In some embodiments of the present application, the areal density of the porous base material is 2 g / m 2 , 3 g / m 2 , 4 g / m 2 , 5 g / m 2 , 6 g / m 2 , 7 g / m 2 , 8 g / m 2 , 9 g / m 2 , 10 g / m 2 , 11 g / m 2 , or any value range between any two of the above values. The areal density of the porous base material is less than 2 g / m 2 . If the thickness of the porous base material is constant, the areal density of the porous base material is less than 2 g / m2 If the process can produce the porous substrate, the porosity in the porous substrate is too much, and when the adhesive layer slurry is coated on the porous substrate, the adhesive layer slurry is easy to enter the porosity of the porous substrate, which affects the speed and quantity of lithium ion shuttling from the insulating layer, thereby affecting the performance of the active material covered by the insulating layer, reducing the capacity of the electrochemical device, and causing the negative electrode sheet to appear lithium precipitation phenomenon. The areal density of the porous substrate is greater than 11 g / m 2 The areal density of the porous substrate is too large, and the porosity in the porous substrate is too small, the ion conducting function of the insulating layer is poor, and the speed and quantity of lithium ion shuttling in the area covered by the insulating layer are greatly reduced and decreased, which will reduce the capacity of the electrochemical device. Further, the areal density of the porous substrate is 3 g / m 2 to 11 g / m 2 While ensuring the capacity improvement, the short circuit risk is further reduced.

[0036] Overall, by selecting a porous substrate including polypropylene and adjusting the areal density of the porous substrate within the above range, the insulating layer has good ion conducting function, and in the area of the positive electrode sheet and the negative electrode sheet pasted with the insulating layer, lithium ions can shuttle freely and quickly like the area without pasting adhesive paper, so that the capacity of the positive and negative active materials in the area covered by the insulating layer can be fully utilized. In this way, the effective area of the positive and negative active material layers is increased, and the capacity of the electrochemical device is improved.

[0037] The adjustment method of the areal density of the porous substrate is not particularly limited in the present application, as long as the purpose of the present application can be achieved. For example, it can be achieved by adjusting the thickness and porosity of the porous substrate. More specifically, it can be achieved by controlling the stretching multiple (2 to 10 times), heating temperature (100°C to 140°C) and the like during the preparation of the porous substrate. Generally, when the porosity of the porous substrate is constant, the thicker the thickness of the porous substrate, the greater the areal density of the porous substrate; the thinner the thickness of the porous substrate, the smaller the areal density of the porous substrate. When the thickness of the porous substrate is constant, the smaller the porosity of the porous substrate, the greater the areal density of the porous substrate; the greater the porosity of the porous substrate, the smaller the areal density of the porous substrate.

[0038] For the convenience of understanding, the insulating layer needs to be explained that, as shown in FIGS. 1 to 3, when the insulating layer 40 is pasted on the positive electrode sheet 10, the longitudinal direction X of the porous substrate 41 is parallel to the extension direction of the positive electrode tab 13, the transverse direction Y of the porous substrate 41 is perpendicular to the extension direction of the positive electrode tab 13, and the thickness direction Z of the porous substrate 41 is perpendicular to both the transverse direction Y and the longitudinal direction X of the porous substrate 41. In some embodiments, as shown in FIG. 1, the insulating layer 40 includes the porous substrate 41, and the thickness of the insulating layer 40 is T 40illustrated. In other embodiments, as shown in Fig. 2, the insulation layer 40 includes a porous substrate 41 and a glue layer 42 disposed on one surface of the porous substrate 41, and the thickness of the insulation layer 40 is T 40 illustrated. It can be understood that the glue layer 42 can also be disposed on the other surface of the porous substrate 41. In the present application, when the insulation layer is provided with a glue layer, the thickness of the insulation layer is the sum of the thickness of the porous substrate and the thickness of the glue layer; when the insulation layer is not provided with a glue layer, the thickness of the insulation layer is the thickness of the porous substrate.

[0039] In some embodiments of the present application, as shown in FIG. 2, the one surface of the porous substrate 41 is provided with a glue layer 42, and of course, in other embodiments, the other surface of the porous substrate 41 can be provided with a glue layer 42. The glue layer comprises a high molecular polymer and inorganic particles; the glass transition temperature of the high molecular polymer is -30℃ to -10℃, and the high molecular polymer comprises a polyacrylate. The above-mentioned polyacrylate includes, but is not limited to, a homopolymer or copolymer polymerized from at least one of the following monomers: methyl acrylate, ethyl acrylate, butyl acrylate. The inorganic particles include at least one of boehmite, aluminum oxide, titanium dioxide, magnesium oxide, zirconium oxide or zinc oxide; the mass percentage content of the high molecular polymer is 30% to 95%, and the mass percentage content of the inorganic particles is 5% to 70%, based on the mass of the glue layer. For example, the glass transition temperature of the high molecular polymer is -30℃, -25℃, -20℃, -16℃, -10℃, or any value within the range between any two of the above-mentioned values. For example, the mass percentage content of the high molecular polymer is 30%, 40%, 45%, 50%, 60%, 70%, 80%, 88%, 95%, or any value within the range between any two of the above-mentioned values. For example, the mass percentage content of the inorganic particles is 5%, 15%, 22%, 30%, 35%, 40%, 50%, 58%, 63%, 70%, or any value within the range between any two of the above-mentioned values. The high molecular polymer with a glass transition temperature within the above-mentioned range is selected for use in the glue layer of the insulation layer, and the glue layer does not need to be subjected to heat pressing treatment, and can have good adhesion at room temperature. The high molecular polymer of the above-mentioned type and with a glass transition temperature within the above-mentioned range is selected, the inorganic particles of the above-mentioned type are selected, and the mass percentage content of the high molecular polymer and the inorganic particles in the glue layer is controlled within the above-mentioned range, and the prepared glue layer can have good adhesion, and the glue layer and the porous substrate, and the glue layer and the positive and negative electrode sheets can all have good adhesion. Thus, the glue layer pasted in the positive or negative electrode sheet can have good protection effect on the positive and negative electrode sheets, and can reduce the probability of short circuit caused by the contact of the positive and negative electrode sheets. And the inorganic particles in the glue layer can make the glue layer have pores, thereby facilitating the shuttling of lithium ions in the glue layer, so that the capacity of the positive and negative active materials in the coverage area of the insulation layer can be fully utilized while the insulation layer plays the adhesion role. Thus, the electrochemical device can have higher capacity without affecting its safety performance. The "glass transition temperature" in the present application is the commonly known glass transition temperature in the art.

[0040] In some embodiments of the present application, the inorganic particles are boehmite. The mass percentage of the high molecular polymer is 30% to 60% and the mass percentage of the inorganic particles is 40% to 70% based on the mass of the adhesive layer. For example, the mass percentage of the high molecular polymer is 30%, 40%, 45%, 50%, 60% or any value between any two of the above-mentioned values. For example, the mass percentage of the inorganic particles is 40%, 50%, 58%, 63%, 70% or any value between any two of the above-mentioned values.

[0041] In some embodiments of the present application, the adhesive layer has holes and part of the porous substrate is exposed from the holes of the adhesive layer, and the diameter of the holes on the adhesive layer is larger than the diameter of the holes of the porous substrate, so as to further improve the ion conducting function of the insulation layer and improve the capacity of the electrochemical device. Figure 4 shows the morphology of the surface of the insulation layer in some embodiments under SEM, the adhesive layer 42 has a plurality of holes, and part of the porous substrate 41 is exposed from the holes of the adhesive layer 42, Figure 5 is an enlarged view of Figure 4, and it can be seen from Figure 5 that the porous substrate 41 has a plurality of small holes, and the diameter of the holes on the adhesive layer 42 is larger than that of the small holes on the porous substrate 41, and Figure 6 is an enlarged view of part of the adhesive layer 42 in Figure 4, and it can be seen from Figure 6 that the adhesive layer 42 has a plurality of inorganic particles.

[0042] In some embodiments of the present application, the longitudinal tensile strength of the porous substrate is 1000 kgf / cm 2 to 2000 kgf / cm 2 , and the transverse tensile strength of the porous substrate is 300 kgf / cm 2 to 600 kgf / cm 2 . For example, the longitudinal tensile strength of the porous substrate is 1000 kgf / cm 2 , 1100 kgf / cm 2 , 1200 kgf / cm 2 , 1330 kgf / cm 2 , 1450 kgf / cm 2 , 1600 kgf / cm 2 , 1700 kgf / cm 2 , 1820 kgf / cm 2 , 1900 kgf / cm 2 , 2000 kgf / cm 2 or any value between any two of the above-mentioned values. For example, the transverse tensile strength of the porous substrate is 300 kgf / cm 2 , 360 kgf / cm 2 , 410 kgf / cm 2 , 500 kgf / cm 2 , 560 kgf / cm 2 , 600 kgf / cm2 or any value range between any two of the above-mentioned values. The longitudinal tensile strength and the transverse tensile strength of the porous substrate are within the above-mentioned ranges, and the porous substrate has both a high longitudinal tensile strength and a high transverse tensile strength. Thus, during the process of preparing the insulation layer, during the process of pasting the insulation layer on the positive and negative electrode sheets, or during the process of preparing the electrochemical device after pasting the insulation layer, the probability of the insulation layer being deformed into a long strip or dumbbell shape is low, the position of the pasted insulation layer is less likely to be exposed due to deformation of the insulation layer, and the risk of positive and negative electrode contact leading to short circuit of the electrochemical device is low. Thus, the electrochemical device can have high safety performance on the basis of having high capacity.

[0043] The method for regulating the longitudinal tensile strength and the transverse tensile strength of the porous substrate is not particularly limited in the present application, as long as the purpose of the present application can be achieved. For example, it can be achieved by regulating the molecular weight and crystallinity of the raw material of the porous substrate, or it can be achieved by regulating the stretching process parameters of the manufacturing equipment of the porous substrate.

[0044] In some embodiments of the present application, the thickness of the insulation layer is 8 μm to 30 μm. For example, the thickness of the insulation layer is 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 21 μm, 24 μm, 26 μm, 28 μm, 30 μm, or any value range between any two of the above-mentioned values. The thickness of the insulation layer is within the above-mentioned range, which is conducive to reducing the possibility of burrs in the positive electrode sheet contacting the negative electrode sheet through the insulation layer or burrs in the negative electrode sheet contacting the positive electrode sheet through the insulation layer, thereby reducing the risk of short circuit of the electrochemical device due to positive and negative electrode contact, and thus improving the safety performance of the electrochemical device. It is also conducive to making the electrochemical device have a smaller volume, thereby reducing the loss of energy density of the electrochemical device due to the increase in volume, and the lithium ions have a shorter shuttle path in the insulation layer and a higher transmission speed, thereby making the electrochemical device have good cycle performance and kinetic performance.

[0045] In some embodiments of the present application, the thickness of the insulation layer is 8 μm to 17 μm. For example, the thickness of the insulation layer is 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, or any value range between any two of the above-mentioned values. By regulating the thickness of the insulation layer within the above-mentioned range, the possibility of burrs on the positive electrode sheet contacting the negative electrode sheet through the insulation layer or burrs on the negative electrode sheet contacting the positive electrode sheet through the insulation layer in the electrochemical device can be reduced without increasing the volume of the electrochemical device, thereby reducing the possibility of loss of energy density of the electrochemical device due to the increase in volume. Thus, the electrochemical device has high safety performance and energy density on the basis of having high capacity.

[0046] In some embodiments of the present application, the thickness T of the porous substrate 41 is 8-20 μm, as shown in FIG. 2. 41 For example, the thickness of the porous substrate is 8 μm, 11 μm, 13 μm, 15 μm, 17 μm, 18 μm, 20 μm, or any value within a range between any two of the above values. Controlling the thickness of the porous substrate within the above range can reduce the possibility of the burrs in the positive electrode tab contacting the negative electrode tab through the insulation layer or the burrs in the negative electrode tab contacting the positive electrode tab through the insulation layer, and can also enable lithium ions in the insulation layer coverage area to shuttle freely, so that the capacity of the active material is fully utilized and the effective area of the positive and negative active material layers is increased. Thus, the electrochemical device has a thinner thickness and a higher volumetric energy density without affecting its safety performance.

[0047] In some embodiments of the present application, the melting temperature of the porous substrate is 165-175 °C. For example, the melting temperature of the porous substrate is 165 °C, 166 °C, 167 °C, 168 °C, 169 °C, 170 °C, 171 °C, 172 °C, 173 °C, 174 °C, 175 °C, or any value within a range between any two of the above values. The melting temperature of the porous substrate is within the above range, and the raw material particles for preparing the porous substrate have a suitable crystallinity, so that the porous substrate has a higher strength, and when the electrochemical device is in a high-temperature state, the risk of short circuit of the electrochemical device caused by melting of the porous substrate is low. Thus, the electrochemical device can have a higher capacity and a higher safety performance.

[0048] The present application does not have a particular limitation on the way of controlling the melting temperature of the porous substrate, as long as the purpose of the present application can be achieved. For example, it can be achieved by controlling the crystallinity and molecular weight of the raw material of the porous substrate.

[0049] The present application does not have a particular limitation on the weight average molecular weight of the above-mentioned high molecular polymer, as long as the purpose of the present application can be achieved.

[0050] In some embodiments of the present application, the thickness T of the adhesive layer 42 is 1-8 μm, as shown in FIG. 2. 42 For example, the thickness of the adhesive layer is 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or any value within a range between any two of the above values. Controlling the thickness of the adhesive layer within the above range can reduce the probability that the energy density of the electrochemical device is impaired due to a large thickness of the insulation layer, and the lithium ions can also have good flowability in the adhesive layer. Thus, the electrochemical device can have a higher capacity.

[0051] In some embodiments of the present application, the Dv50 of the inorganic particles is 80 nm to 1000 nm. For example, the Dv50 of the inorganic particles is 80 nm, 100 nm, 200 nm, 230 nm, 300 nm, 400 nm, 480 nm, 520 nm, 600 nm, 660 nm, 780 nm, 810 nm, 900 nm, 1000 nm, or any value within a range between any two of the above values. By adjusting the Dv50 of the inorganic particles within the above range, the inorganic particles can be uniformly distributed in the adhesive layer slurry, and when the adhesive layer compound is coated on the surface of the porous substrate, the probability of the inorganic particles entering the pores of the porous substrate is small, the probability of reducing the porosity of the porous substrate is low, thereby making the insulation layer have good ion conduction function, and also enabling the insulation layer to have good adhesion. In this way, when the insulation layer is applied to an electrochemical device, the electrochemical device can have high capacity and good safety performance.

[0052] In the present application, "Dv50" refers to the particle size at which the cumulative volume of inorganic particles reaches 50% from the small particle size side in the particle size distribution on a volume basis.

[0053] The present application does not have a particular limitation on the adjustment method of the Dv50 of the inorganic particles, as long as the purpose of the present application can be achieved. For example, it can be achieved by crushing and sieving. Alternatively, commercially available inorganic particles can be purchased, and the Dv50 of the inorganic particles can be determined by combining the test method of "Test of Dv50 of Inorganic Particles" in the present application, and selecting inorganic particles with the desired Dv50.

[0054] For ease of understanding, it is defined that in the unfolded state of the electrode sheet, the length direction of the positive electrode sheet itself is the same as the transverse direction of the insulation layer, the width direction of the positive electrode sheet itself is the same as the longitudinal direction of the insulation layer, and the thickness direction of the positive electrode sheet itself is the same as the thickness direction of the insulation layer. It can be understood that the length direction, width direction, and thickness direction of the positive current collector, positive active material layer, negative electrode sheet, and separator are the same as those of the positive electrode sheet.

[0055] In some embodiments of this application, the positive electrode includes a positive current collector, a positive active material layer, and a positive electrode tab. The positive current collector includes a first surface and a second surface opposite to each other. The positive active material layer is at least disposed on the first surface of the positive current collector. A first groove is provided in the positive active material layer to expose the positive current collector. The positive electrode tab is disposed in the first groove and connected to the positive current collector. The second surface includes a first empty foil area opposite to the first groove. An insulating layer is adhered to at least one of the following: the surface of the positive electrode tab, the first empty foil area, the surface of the negative electrode adjacent to the first groove, the surface of the negative electrode adjacent to the first empty foil area, or the end area of ​​the positive electrode. The phrase "the positive active material layer is at least disposed on the first surface of the positive current collector" means that in some embodiments, the positive active material layer is disposed on the first surface of the positive current collector; in other embodiments, the positive active material layer is disposed on both the first and second surfaces of the positive current collector. The "first surface" and the "second surface" can be part or all of the surfaces of the positive current collector. It should be noted that the negative electrode in the "negative electrode surface adjacent to the first groove" and the negative electrode in the "negative electrode surface adjacent to the first empty foil area" are not the same layer of negative electrode. They are two layers of negative electrode adjacent to the positive electrode respectively. The above-mentioned "two layers of negative electrode" can be two negative electrode or two layers formed by winding one negative electrode. As shown in Figure 7, the separator 30 is located between the positive electrode 10 and the negative electrode 20. The positive electrode 10 includes a positive current collector 11, a positive active material layer 12, and a positive electrode tab 13. The positive current collector 11 includes a first surface 11a and a second surface 11b opposite to each other along its thickness direction Z. The positive active material layer 12 is disposed on the first surface 11a of the positive current collector 11 and also on the second surface 11b of the positive current collector 11. The positive active material layer 12 disposed on the first surface 11a has a first groove 15 exposing the positive current collector 11. The positive electrode tab 13 is disposed in the first groove 15 and connected to the positive current collector 11. The second surface 11b includes a first empty foil area 16 opposite to the first groove 15. Insulating layers 40 are respectively attached to the surface of the positive electrode tab 13, the first empty foil area 16, the surface of the negative electrode 20 adjacent to the first groove 15, the surface of the negative electrode 20 adjacent to the first empty foil area 16, and the ending area of ​​the positive electrode 10. Typically, along the length Y of the positive electrode 10, the length of the insulating layer 40 attached to the surface of the positive electrode tab 13 and the first empty foil area 16 is greater than the length of the insulating layer 40 attached to the surface of the negative electrode 20 adjacent to the first groove 15 and the surface of the negative electrode 20 adjacent to the first empty foil area 16.Adhering the insulating layer to the surface of the positive electrode tab and the surface of the negative electrode sheet adjacent to the first groove can reduce the probability of burrs on the positive electrode tab penetrating the negative electrode active material layer and contacting the negative electrode current collector, thus causing a short circuit. In the area of ​​the positive electrode active material layer covered by the insulating layer on the surface of the positive electrode tab, lithium ions can be normally extracted and then normally embedded in the corresponding negative electrode active material layer, thereby reducing capacity waste and the probability of lithium plating. Adhering the insulating layer to the first empty foil area and the surface of the negative electrode sheet adjacent to the first empty foil area can reduce the probability of burrs in the first empty foil area penetrating the negative electrode active material layer and contacting the negative electrode current collector, thus causing a short circuit. In the area of ​​the first empty foil area covered by the insulating layer covered by the positive electrode active material layer, lithium ions can be normally extracted and then normally embedded in the corresponding negative electrode active material layer, thereby reducing capacity waste and the probability of lithium plating. Adhering the insulating layer to the end area of ​​the positive electrode sheet can reduce the probability of the positive electrode current collector contacting the negative electrode sheet. Therefore, by attaching the insulating layer to the above-mentioned different locations, lithium ions in the area covered by the insulating layer can freely move around to exert the capacity of the active material, and the risk of short circuit caused by positive and negative electrode contact can also be reduced, thereby giving the electrochemical device high energy density and good safety performance.

[0056] In some embodiments of this application, the negative electrode sheet includes a negative current collector, a negative active material layer, and a negative electrode tab. The negative current collector includes a third surface and a fourth surface opposite to each other. The negative active material layer is disposed at least on the third surface of the negative current collector. A second groove is provided in the negative active material layer to expose the negative current collector. The negative electrode tab is disposed in the second groove and connected to the negative current collector. The fourth surface includes a second empty foil area opposite to the second groove. An insulating layer is adhered to at least one part of the surface of the negative electrode tab or the second empty foil area. The phrase "the negative active material layer is disposed at least on the third surface of the negative current collector" means that in some embodiments, the negative active material layer is disposed on the third surface of the negative current collector, and in other embodiments, the negative active material layer is disposed on both the third and fourth surfaces of the negative current collector. As shown in Figure 8, the separator 30 is located between the positive electrode 10 and the negative electrode 20. The negative electrode 20 includes a negative current collector 21, a negative active material layer 22, and a negative electrode tab 23. The negative current collector 21 includes a third surface 21c and a fourth surface 21d opposite each other along its thickness direction Z. The negative active material layer 22 is disposed on the third surface 21c and the fourth surface 21d of the negative current collector 21. A second groove 25 is provided in the negative active material layer 22 located on the third surface 21c, exposing the negative current collector 21. The negative electrode tab 23 is disposed in the second groove 25 and connected to the negative current collector 21. The fourth surface 21d includes a second empty foil region 26 opposite to the second groove 25. An insulating layer 40 is attached to the surface of the negative electrode tab 23 and the second empty foil region 26. A non-ion-conducting insulating layer 50 is attached to the surface of the positive electrode 10 adjacent to the second groove 25 and the surface of the positive electrode 10 adjacent to the second empty foil region 26. By attaching the insulating layer to the surface of the negative electrode tab and the second empty foil area, lithium ions can be embedded into the negative electrode active material layer covered by the insulating layer, increasing the lithium ion embedding sites and the capacity of the negative electrode active material layer, thereby giving the electrochemical device a higher energy density.

[0057] This application does not impose any particular restrictions on the type of non-ion-conducting insulating layer. Any non-ion-conducting insulating layer known in the art can be selected as needed, as long as it can achieve the purpose of this application.

[0058] This application does not impose any particular restrictions on the type of positive electrode current collector, as long as it can achieve the purpose of this application. For example, the positive electrode current collector may include aluminum foil, aluminum alloy foil, etc.

[0059] This application does not impose any particular limitation on the positive electrode active material layer, as long as it achieves the purpose of this application. In one embodiment of this application, the positive electrode active material layer includes a positive electrode active material. This application does not impose any particular limitation on the type of positive electrode active material, as long as it achieves the purpose of this application. For example, the positive electrode active material may include at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganese oxide, lithium manganese iron phosphate, or lithium titanate. Optionally, the positive electrode active material layer may also include a positive electrode conductive agent and a positive electrode binder. This application does not impose any particular limitation on the type of positive electrode conductive agent and positive electrode binder in the positive electrode active material layer, as long as it achieves the purpose of this application. This application does not impose any particular limitation on the mass ratio of the positive electrode active material, positive electrode conductive agent, and positive electrode binder in the positive electrode active material layer; those skilled in the art can select according to actual needs, as long as it achieves the purpose of this application.

[0060] This application does not impose any particular limitations on the thickness of the positive electrode current collector and the positive electrode active material layer, as long as the purpose of this application can be achieved. For example, the thickness of the positive electrode current collector can be 5 μm to 20 μm, and the thickness of the positive electrode active material layer can be 30 μm to 120 μm.

[0061] This application does not impose any particular restrictions on the negative electrode current collector, as long as it can achieve the purpose of this application. For example, the negative electrode current collector may include copper foil, copper alloy foil, nickel foil, titanium foil, nickel foam, or copper foam, etc.

[0062] This application does not impose any particular limitation on the negative electrode active material layer, as long as it achieves the purpose of this application. In one embodiment of this application, the negative electrode active material layer includes a negative electrode active material. This application does not impose any particular limitation on the type of negative electrode active material, as long as it achieves the purpose of this application. For example, the negative electrode active material may include at least one of natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, tin-based materials, silicon-based materials, lithium titanate, transition metal nitrides, or natural flake graphite. Optionally, the negative electrode active material layer may also include at least one of a negative electrode conductive agent, a thickener, and a negative electrode binder. This application does not impose any particular limitation on the types of negative electrode conductive agents, thickeners, and negative electrode binders in the negative electrode active material layer, as long as they achieve the purpose of this application. This application does not impose any particular limitation on the mass ratio of the negative electrode active material, negative electrode conductive agent, thickener, and negative electrode binder in the negative electrode active material layer, as long as they achieve the purpose of this application.

[0063] This application does not impose any particular limitations on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of this application can be achieved. For example, the thickness of the negative electrode current collector can be 5 μm to 20 μm, and the thickness of the negative electrode active material layer can be 30 μm to 120 μm.

[0064] This application does not impose any particular limitation on the diaphragm, as long as it can achieve the purpose of this application. For example, the diaphragm material may include, but is not limited to, at least one of polyethylene (PE), polyolefin (PO) based on polypropylene (PP), polyester (e.g., polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex, or aramid. The type of diaphragm may include at least one of woven membrane, nonwoven membrane, microporous membrane, composite membrane, rolled membrane, or spun membrane.

[0065] The electrochemical device of this application also includes a packaging bag and an electrolyte. The insulating layer, positive electrode, negative electrode, diaphragm, and electrolyte are contained in the packaging bag. This application does not impose any particular restrictions on the packaging bag and electrolyte; any packaging bag and electrolyte known in this application may be selected according to actual needs, as long as the purpose of this application can be achieved.

[0066] This application does not impose any particular limitation on the type of electrochemical device, which may include any device in which an electrochemical reaction occurs. For example, electrochemical devices may include, but are not limited to: lithium metal secondary batteries, lithium-ion secondary batteries, sodium-ion secondary batteries, lithium polymer secondary batteries, and lithium-ion polymer secondary batteries.

[0067] This application does not impose any particular restrictions on the preparation method of the insulating layer, as long as it can achieve the purpose of this application. For example, the preparation method of the insulating layer includes, but is not limited to, the following steps: (1) mixing inorganic particles and polymer, adding solvent, and stirring evenly to obtain an adhesive slurry; (2) coating the adhesive slurry onto the surface of a release film using a micro-grooved roller, during the drying process the slurry forms a film and shrinks, finally forming a porous adhesive layer, after the adhesive layer is combined with a porous substrate, a release agent is placed on the surface of the porous substrate away from the adhesive layer, after drying, an insulating layer is obtained, wound up, slit, and ready for use. This application does not impose any particular restrictions on the solid content of the adhesive slurry, as long as it can achieve the purpose of this application. For example, the solid content of the adhesive slurry is 10wt% to 30wt%. This application does not impose any particular restrictions on the type of "solvent" mentioned above, as long as it can achieve the purpose of this application. This application does not impose any particular restrictions on the drying and drying temperature in step (2) above, as long as it can achieve the purpose of this application. This application does not impose any particular restrictions on the release film and release agent mentioned above. Those skilled in the art can select any known release film and release agent according to the actual situation, as long as the purpose of this application can be achieved.

[0068] This application does not impose any particular limitation on the preparation method of the electrochemical device. Any preparation method known in the art can be used, as long as it can achieve the purpose of this application. For example, the preparation method of the electrochemical device includes, but is not limited to, the following steps: stacking the positive electrode, the separator, and the negative electrode in sequence, attaching an insulating layer, and then, as needed, winding, folding, or performing other operations to obtain a wound electrode assembly; placing the electrode assembly in a packaging bag, injecting electrolyte into the packaging bag, and sealing the bag to obtain the electrochemical device; or, stacking the positive electrode, the separator, and the negative electrode in sequence, attaching an insulating layer, fixing the four corners of the entire stacked structure to obtain a stacked electrode assembly, placing the electrode assembly in a packaging bag, injecting electrolyte into the packaging bag, and sealing the bag to obtain the electrochemical device.

[0069] A second aspect of this application provides an electronic device comprising the electrochemical device described in any of the foregoing embodiments. Therefore, the electrochemical device exhibits excellent performance.

[0070] There are no particular limitations on the electronic devices covered by this application, which may include, but are not limited to, the following: laptops, pen-based computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, and lithium-ion capacitors, etc.

[0071] Example

[0072] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below.

[0073] Test methods and equipment:

[0074] Method for extracting porous substrates from lithium-ion batteries:

[0075] In lithium-ion batteries, if the insulating layer is located between the negative electrode and the separator, after removing the insulating layer from the lithium-ion battery, the insulating layer is placed sequentially in a mixed solvent of toluene and ethyl acetate (mass ratio of toluene to ethyl acetate 7:3) and water, stirred at 50°C for 20 minutes, then removed and dried at 100°C for 2 hours until no solution remains, thus obtaining a porous substrate. If the insulating layer is located on the positive electrode and between the separator, after removing the insulating layer from the lithium-ion battery, the insulating layer is placed in N-methylpyrrolidone (NMP), stirred at 50°C for 20 minutes, then removed and dried at 100°C for 2 hours until no solution remains, thus obtaining a porous substrate.

[0076] Thickness testing:

[0077] (1) Insulation layer thickness T 40 The test:

[0078] Remove the positive and negative electrode plates from the lithium-ion battery and measure the thickness T of the insulating layer attached to the electrode plates. 总 Thickness T of the unadhesive area 极片 Insulation layer thickness T 40 =T 总 -T 极片 .

[0079] (2) Thickness T of porous substrate 41 The test:

[0080] The thickness of the porous substrate sample was randomly measured at six locations, and the average value was calculated to obtain the thickness T of the porous substrate. 41 .

[0081] (3) Adhesive layer thickness T 42 The test:

[0082] Based on the aforementioned insulation layer thickness T 40 and the thickness T of the porous substrate 41 The thickness T of the adhesive layer was calculated. 42 :T 42 =T 40 -T 41 .

[0083] Testing the areal density of porous substrates:

[0084] The length and width of the porous substrate were measured using a magnifying glass (CCD, 30x magnification), and the area s was calculated in meters. 2 Weigh a porous substrate with a known area s using an electronic balance; the weight is M, and the unit is g. Surface density (g / m³) 2 = M / s.

[0085] Testing of longitudinal and transverse tensile strength of porous substrates:

[0086] (1) Test of longitudinal tensile strength:

[0087] A high-speed rail tensile testing machine is used to clamp the two ends of a long, perforated substrate along its longitudinal direction. The cross-sectional area of ​​the perforated substrate is A (the cross-sectional area of ​​the perforated substrate is calculated as the cross-sectional length of the perforated substrate × the thickness of the perforated substrate). The tensile force F is obtained by testing at a tensile speed of 120 mm / min. A Longitudinal tensile strength Rm v =F A / A.

[0088] (2) Test of transverse tensile strength:

[0089] A high-speed rail tensile testing machine is used to clamp the two transverse ends of a long strip of perforated substrate. The longitudinal cross-sectional area of ​​the perforated substrate is B (longitudinal length of the perforated substrate × thickness of the perforated substrate = longitudinal cross-sectional area of ​​the perforated substrate). The tensile force F is obtained by testing at a tensile speed of 120 mm / min. B Transverse tensile strength Rm c =F B / B.

[0090] Testing the melting temperature of porous substrates:

[0091] Take about 3mg of porous substrate and test it using a differential scanning calorimeter (DSC) (DSC range 0mW to 600mW, temperature fluctuation ±0.1℃, temperature range -35℃ to 600℃). Select the peak temperature of the melting peak as the melting temperature.

[0092] Discharge capacity testing:

[0093] (1) Place the lithium-ion battery in an environment of 25°C;

[0094] (2) Charge the lithium-ion battery to the charging cutoff voltage (e.g., 4.5V) at a constant current of 0.2C, and charge the lithium-ion battery to 0.02C at a constant voltage of the charging cutoff voltage.

[0095] (3) Let the lithium-ion battery stand for 10 minutes;

[0096] (4) Discharge the lithium-ion battery to the discharge cutoff voltage (e.g., 3.0V) at a constant current of 0.1C to extract the discharge capacity of the lithium-ion battery.

[0097] Short circuit test:

[0098] At 20±5℃, the lithium-ion battery sample was charged to 100% SOC (i.e., fully charged state). The sample was placed face up on the test platform. A 25mm diameter round rod was placed perpendicular to the extension direction of the lithium-ion battery tabs in the sample tab welding area (where the welding protective adhesive is applied). The extrusion speed was 0.1mm / s. When the extrusion force reached 10±0.78kN, the extrusion was stopped. The above test was repeated for 20 samples. The criteria for passing the test were: no fire, no explosion, and no smoke.

[0099] Lithium-ion battery thickness testing:

[0100] After charging the lithium-ion battery to 60% SOC (State of Charge), the thickness of the lithium-ion battery is tested using a pouch cell thickness gauge (PPG) (pressure 700g). The average value of three measurements is taken to obtain the thickness of the lithium-ion battery.

[0101] Example 1-1

[0102] <Preparation of Insulating Layer>

[0103] Inorganic boehmite particles and polymethyl methacrylate (glass transition temperature Tg = -30℃) were mixed, and deionized water was added as a solvent. The mixture was stirred until homogeneous to obtain a slurry with a solid content of 20 wt%. The Dv50 of the inorganic particles was 100 nm.

[0104] The above adhesive slurry was coated onto the surface of a PET release film with a release force of 10g using a micro-grooving roller, and dried at 110°C to form a film with a thickness of T. 42 =3μm adhesive layer, and then at the winding point, the adhesive layer is bonded to the porous substrate (thickness T) 41 A 9μm biaxially oriented polypropylene (BOPP) film (manufacturer: Dalian Yike Energy Technology Co., Ltd., model: ECO-9) is laminated, and the adhesive layer is transferred to the surface of a porous substrate. The product is then wound up to obtain an intermediate product containing a release film and the porous substrate. A silicone release agent (manufacturer: Dow Corning) is applied to the porous substrate side (opposite to the adhesive layer) of the intermediate product using a micro-gravity roller. After drying, the release film is removed while the porous substrate is wound up to obtain a product with a thickness T. 40 An insulating layer with a diameter of 12 μm (the surface of the insulating layer is shown in Figure 4).

[0105] Among them, the longitudinal tensile strength Rm of the porous substrate v =1500kgf / cm 2 Transverse tensile strength Rm c =500kgf / cm 2 Surface density = 5g / m³ 2 Melting temperature = 170℃. Based on the mass of the adhesive layer, the mass percentage of the polymer W1 = 50%, and the mass percentage of the inorganic particles W2 = 50%.

[0106] <Preparation of the positive electrode>

[0107] Lithium cobalt oxide (CCO), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) (a binder) were mixed at a mass ratio of 97.2:1.5:1.3. NMP was added as a solvent, and the mixture was stirred under vacuum until a homogeneous CCO slurry with a solid content of 72 wt% was obtained. The CCO slurry was uniformly coated onto one surface of a 10 μm thick aluminum foil current collector and dried at 85°C to obtain a single-sided CCO electrode sheet with a 90 μm thick active material layer. The above steps were then repeated on the other surface of the aluminum foil to obtain a double-sided CCO electrode sheet. After cold pressing, cutting, and welding of CCO tabs, a 70 mm × 1400 mm CCO electrode sheet was obtained for use.

[0108] <Preparation of Negative Electrode Sheets>

[0109] Graphite (negative electrode active material), sodium carboxymethyl cellulose (negative electrode thickener), and styrene-butadiene rubber (negative electrode binder) were mixed at a mass ratio of 98:1:1. Deionized water was then added as a solvent, and the mixture was stirred under vacuum until a homogeneous negative electrode slurry with a solid content of 42 wt% was obtained. The negative electrode slurry was uniformly coated onto one surface of an 8 μm thick copper foil current collector and dried at 85°C to obtain a negative electrode sheet with a single-sided coating of the negative electrode active material layer (60 μm thick). The above steps were then repeated on the other surface of the copper foil to obtain a negative electrode sheet with a double-sided coating of the negative electrode active material layer. After cold pressing, cutting, and welding of nickel tabs, a negative electrode sheet with dimensions of 74 mm × 1408 mm was obtained for later use.

[0110] <Preparation of the diaphragm>

[0111] The diaphragm base membrane is 8μm thick polyethylene (PE). A 2μm thick alumina ceramic layer is coated on each of the two surfaces of the base membrane along its thickness direction. Finally, a 2.5mg / cm² coating is applied to each of the two surfaces of the ceramic layer along its thickness direction. 2 The PVDF binder is dried to obtain the diaphragm.

[0112] <Preparation of Electrolyte>

[0113] In an environment with a water content of less than 10 ppm, a basic electrolyte was prepared by mixing non-aqueous organic solvents propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a mass ratio of 1:1:0.5:1. Lithium hexafluorophosphate (LiPF6) was then added and mixed evenly to obtain the electrolyte, wherein the concentration of LiPF6 was 1 mol / L.

[0114] <Preparation of Lithium-ion Batteries>

[0115] The negative electrode sheet, separator, and positive electrode sheet prepared above are stacked and wound in sequence to obtain a wound electrode assembly. The electrode assembly is placed in an aluminum-plastic film packaging bag, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, capacity testing, degassing, and edge trimming, a lithium-ion battery is obtained.

[0116] As shown in Figure 7, the surface of the positive electrode tab 13, the first empty foil area 16, the surface of the negative electrode 20 adjacent to the first groove 15, the surface of the negative electrode 20 adjacent to the first empty foil area 16, and the tail area of ​​the positive electrode 10 are all covered with an insulating layer 40; as shown in Figure 8, the surface of the negative electrode tab 23 and the second empty foil area 26 are covered with an insulating layer 40, and the surface of the positive electrode 10 adjacent to the second groove 25 and the surface of the positive electrode 10 adjacent to the second empty foil area 26 are covered with a non-ion-conducting insulating layer 50 (manufacturer: Top Chemical (Shanghai) Co., Ltd., model: T4116BR).

[0117] Examples 1-2 to Examples 1-15

[0118] Except for adjusting the relevant preparation parameters in Table 1, the rest is the same as in Example 1-1.

[0119] Examples 1-16

[0120] Except for replacing the porous substrate in the <Preparation of Insulation Layer> with a uniaxially stretched polypropylene film (manufacturer: Shenzhen Xingyuan Material Technology Co., Ltd., model: SD216101), the rest is the same as in Example 1-1.

[0121] Examples 2-1 to 2-11

[0122] Except for adjusting the relevant preparation parameters in Table 2, the rest is the same as in Examples 1-1.

[0123] Examples 3-1 to 3-3

[0124] Except for adjusting the relevant preparation parameters in Table 3, the rest is the same as in Example 1-1.

[0125] Comparative Example 1

[0126] Except for replacing the insulating layer in <Preparation of Insulating Layer> with green adhesive (manufacturer: Dongguan Aozhong New Material Technology Co., Ltd., porosity 0%), the green adhesive includes a substrate and an adhesive layer disposed on one surface of the substrate. The substrate material is PET and the adhesive layer material is polymethyl acrylate. Otherwise, it is the same as in Example 1-1.

[0127] Comparative Example 2 and Comparative Example 3

[0128] Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as in Example 1-1.

[0129] The preparation and performance parameters of each embodiment and comparative example are shown in Tables 1 to 3.

[0130] Table 1 Note: "-" in Table 1 indicates that the corresponding performance parameter cannot be measured. This is because the areal density of the porous substrate is too small, indicating that the porosity of the porous substrate is too high, and it cannot be prepared into a porous substrate, so it cannot be used in lithium batteries.

[0131] As can be seen from Examples 1-1 to 1-16 and Comparative Examples 1 to 3, the lithium-ion batteries of this application, by selecting a porous substrate including polypropylene and controlling the areal density of the porous substrate within the range of this application, achieve high capacity and low thickness, indicating that the lithium-ion batteries have high capacity and energy density. In contrast, the lithium-ion batteries of the comparative examples do not have at least one of the types of porous substrates or the areal density of the porous substrates within the range of this application, and therefore the lithium-ion batteries of the comparative examples cannot be used normally or have low capacity.

[0132] The type of porous substrate typically affects the safety performance and capacity of lithium-ion batteries. As can be seen from Examples 1-1, 1-16, and Comparative Example 1, lithium-ion batteries using porous substrates within the scope of this application exhibit higher capacity and smaller thickness. Compared to Examples 1-16, the lithium-ion battery in Example 1-1 uses BOPP as the porous substrate, which achieves higher capacity and energy density without compromising safety performance.

[0133] Areal density and longitudinal tensile strength Rm of porous substrates v Transverse tensile strength Rm c Melting temperature typically affects the safety performance and capacity of lithium-ion batteries. As can be seen from Examples 1-1 to 1-9, Comparative Examples 2 and 3, the areal density and longitudinal tensile strength Rm of the selected porous substrate are... v Transverse tensile strength Rm c Lithium-ion batteries with melting temperatures within the range described in this application can achieve high capacity and low thickness while maintaining good safety performance. Furthermore, the areal density is controlled at 3 g / m². 2 Up to 11g / m 2 This allows the substrate to maintain appropriate tensile strength, reducing the risk of the insulation layer being deformed into a dumbbell shape during the bonding process. This reduces the width of the insulation layer in the transverse direction of the substrate, making it unable to cover the originally designed coverage area. As a result, the area originally covered by the electrode is exposed, and some welding areas cannot be protected. This leads to the risk of short circuits in the electrochemical device caused by positive and negative electrode contact, further improving the safety performance caused by short circuits in the lug welding area.

[0134] The thickness of the insulating layer typically affects the safety performance and capacity of lithium-ion batteries. As can be seen from Examples 1-1, 1-10 to 1-15, lithium-ion batteries with insulating layer thicknesses within the range of this application can achieve high capacity while maintaining good safety performance.

[0135] The thickness of the porous substrate typically affects the safety performance and capacity of lithium-ion batteries. As can be seen from Examples 1-1, 1-9, and 1-10, lithium-ion batteries using porous substrates with thicknesses within the range of this application can achieve high capacity while maintaining good safety performance.

[0136] The thickness of the adhesive layer typically affects the safety performance and capacity of lithium-ion batteries. (From Examples 1-1, 1-11 to...)

[0137] As can be seen from Examples 1-13, lithium-ion batteries with a porous substrate thickness within the range of this application can have high capacity while maintaining good safety performance.

[0138] Table 2

[0139] The types of polymers and inorganic particles typically affect the safety performance and capacity of lithium-ion batteries. As can be seen from Examples 1-1, 2-1 to 2-7, lithium-ion batteries using polymers and inorganic particles within the scope of this application can achieve high capacity while maintaining good safety performance.

[0140] The mass percentage of polymeric materials and inorganic particles in the adhesive layer typically affects the safety performance and capacity of lithium-ion batteries. As can be seen from Examples 1-1, 2-8 to 2-11, lithium-ion batteries with a mass percentage of polymeric materials and inorganic particles within the scope of this application can achieve high capacity while maintaining good safety performance.

[0141] Table 3

[0142] The Dv50 of inorganic particles typically affects the safety performance and capacity of lithium-ion batteries. As can be seen from Examples 1-1, 3-1 to 3-3, lithium-ion batteries using inorganic particles with Dv50 within the scope of this application can achieve high capacity while maintaining good safety performance.

[0143] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0144] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0145] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An electrochemical device comprising an insulating layer, a positive electrode tab, a negative electrode tab, and a separator disposed between the positive electrode tab and the negative electrode tab, the positive electrode tab comprising a positive electrode tab, the insulating layer being interposed between the separator and the positive electrode tab, or the insulating layer being interposed between the separator and a tail end region of the positive electrode tab; the insulating layer comprising a porous substrate; wherein, The apertured substrate comprises polypropylene, the areal density of the apertured substrate is 2 g / m 2 up to 11 g / m 2 .

2. The electrochemical device of claim 1, wherein, The areal density of the apertured substrate is 3 g / m 2 up to 11 g / m 2 .

3. The electrochemical device of claim 1, wherein, The adhesive layer is arranged on one surface of the porous substrate, and the adhesive layer comprises a high polymer and inorganic particles; The high polymer has a glass transition temperature of -30℃ to -10℃, and the high polymer comprises a polyacrylate; The inorganic particles comprise at least one of boehmite, aluminum oxide, titanium dioxide, magnesium oxide, zirconium oxide or zinc oxide; The high polymer has a mass percentage of 30% to 95%, and the inorganic particles have a mass percentage of 5% to 70% based on the mass of the adhesive layer.

4. The electrochemical device according to claim 3, wherein the inorganic particles are boehmite, the high polymer has a mass percentage of 30% to 60%, and the inorganic particles have a mass percentage of 40% to 70% based on the mass of the adhesive layer.

5. The electrochemical device of claim 3, wherein, The adhesive layer is provided with holes, and part of the porous substrate is exposed from the holes of the adhesive layer.

6. The electrochemical device according to any one of claims 1 to 5, wherein, The longitudinal tensile strength of the perforated substrate is 1000 kgf / cm 2 to 2000 kgf / cm 2 The transverse tensile strength of the perforated substrate is 300 kgf / cm 2 to 600 kgf / cm 2 .

7. The electrochemical device according to any one of claims 1 to 5, wherein, The thickness of the insulating layer is 8μm to 30μm.

8. The electrochemical device according to any one of claims 1 to 5, wherein, The thickness of the insulating layer is 8μm to 17μm.

9. The electrochemical device according to any one of claims 1 to 5, wherein, The thickness of the porous substrate is 8μm to 20μm.

10. The electrochemical device according to any one of claims 3 to 5, wherein, The thickness of the adhesive layer is 1μm to 8μm.

11. The electrochemical device according to claim 3 or 4, wherein The Dv50 of the inorganic particles is 80nm to 1000nm.

12. The electrochemical device according to any one of claims 1 to 5, wherein, The melting temperature of the porous substrate is 165℃ to 175℃.

13. The electrochemical device according to any one of claims 1 to 5, wherein, The positive electrode tab comprises a positive electrode active material layer and a positive electrode current collector, the positive electrode current collector comprises opposite first and second surfaces, the positive electrode active material layer is arranged on at least the first surface of the positive electrode current collector, the positive electrode active material layer is provided with a first groove exposing the positive electrode current collector, the positive electrode tab is arranged in the first groove and connected with the positive electrode current collector, and the second surface comprises a first empty foil area opposite the first groove; The insulating layer is attached to at least one of the surface of the positive electrode tab, the first empty foil area, the surface of the negative electrode tab adjacent to the first groove, the surface of the negative electrode tab adjacent to the first empty foil area, or the end area of the positive electrode tab.

14. The electrochemical device according to any one of claims 1 to 6, wherein, The negative electrode tab comprises a negative electrode current collector, a negative electrode active material layer and a negative electrode tab, the negative electrode current collector comprises opposite third and fourth surfaces, the negative electrode active material layer is arranged on at least the third surface of the negative electrode current collector, the negative electrode active material layer is provided with a second groove exposing the negative electrode current collector, the negative electrode tab is arranged in the second groove and connected with the negative electrode current collector, and the fourth surface comprises a second empty foil area opposite the second groove. The insulating layer is attached to at least one of the surface of the negative electrode tab or the second empty foil area.

15. An electronic device comprising the electrochemical device according to any one of claims 1 to 14.

Images