A battery

Abstract

The application relates to the technical field of batteries, and discloses a battery; wherein the battery comprises a pole piece, a diaphragm and an electrolyte, the diaphragm comprises a carrier layer and a coating layer arranged on at least one side surface of the carrier layer, the coating layer comprises a plurality of glue points; the glue points are located between the carrier layer and the pole piece, and a gap is arranged between the pole piece and the carrier layer and located between two adjacent glue points; a plurality of sections between the pole piece and the diaphragm are taken along the thickness direction of the diaphragm; in the sections, the difference between the maximum value and the minimum value of the length H of the gap is less than or equal to 1000 microns, and the difference between the maximum value and the minimum value of the width h of the gap is less than or equal to 5 microns. Through optimization of the gap between the diaphragm and the pole piece, the cycle capacity retention rate of the lithium battery and the low-temperature discharge performance are improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a battery. Background Technology

[0002] Lithium-ion batteries are characterized by high energy density, high operating voltage, and small size, and are widely used in consumer electronics, automobiles, and other fields. With the widespread application of lithium-ion batteries, the market is placing increasingly higher demands on their performance, such as ultra-long cycle life and high-rate discharge performance.

[0003] During repeated charge-discharge cycles, the electrolyte in lithium-ion batteries is continuously consumed. Especially under high-temperature cycling and storage conditions, various complex side reactions accelerate the consumption rate of electrolyte, causing the lithium battery to quickly enter a low electrolyte state. This leads to a significant increase in the DC internal resistance (DCIR) of the lithium battery, resulting in deterioration of the low-temperature discharge performance and a rapid decline in cycle capacity retention. Summary of the Invention

[0004] In view of this, the present invention provides a battery and electrical device that solves the problems of battery low-temperature discharge performance degradation and rapid decay of cycle capacity retention rate, and can better slow down the rate of decrease in battery cycle capacity retention rate and improve the low-temperature discharge performance of lithium battery.

[0005] In a first aspect, the present invention provides a battery comprising an electrode, a separator, and an electrolyte. The separator comprises a carrier layer and a coating disposed on at least one surface of the carrier layer. The coating comprises a plurality of adhesive dots. The adhesive dots are located between the carrier layer and the electrode, and there is a gap between the electrode and the carrier layer between two adjacent adhesive dots. The length of the gap is H μm, and the width of the gap is h μm. Along the thickness direction of the diaphragm, several cross sections are taken between the electrode and the diaphragm; in the cross sections, the difference between the maximum and minimum values ​​of the gap length H is less than or equal to 1000 μm, the difference between the maximum and minimum values ​​of the gap width h is less than or equal to 5 μm, and the number of the cross sections is greater than or equal to 5.

[0006] In one optional embodiment, the length H of the gap in the cross section is 50μm-1200μm, preferably 150μm-800μm; And / or, the width h of the gap in the cross section is 0.5μm-8μm, preferably 1μm-4μm; And / or, the area of ​​the gap is 150 μm. 2 -2000μm 2 Preferably 250μm 2 -2000μm 2 .

[0007] In one optional embodiment, the difference between the maximum and minimum values ​​of the gap length H in the cross section is 10 μm to 1000 μm. And / or, in the cross section, the difference between the maximum and minimum values ​​of the gap width h is 0.1 μm-5 μm, preferably 0.1 μm-2 μm.

[0008] In one optional embodiment, the adhesive dots comprise polymer particles, and the average diameter of the adhesive dots is 10 μm-1500 μm; And / or, the coverage of the adhesive dots on the carrier layer is 10%-30%.

[0009] Furthermore, the polymer particles include primary particles and secondary particles formed by the aggregation of primary particles; wherein the average particle size of the primary particles is 0.1 μm-0.5 μm; And / or, the average diameter of the adhesive dots is 100μm-1000μm; And / or, the polymer particles are selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride, modified polyvinylidene fluoride-hexafluoropropylene and its copolymers, polyimide, polyacrylonitrile, polymethyl methacrylate, and polyacrylic acid.

[0010] In one alternative embodiment, the carrier layer includes a substrate layer, or the carrier layer includes a substrate layer and a heat-resistant layer disposed on the substrate layer. The substrate layer is a polyolefin porous base membrane, and the material of the substrate layer is one or more of polyethylene, polypropylene, or polyethylene-polypropylene composite material; The heat-resistant layer includes heat-resistant particles, which are made of one or more of the following materials: boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon dioxide, tin dioxide, titanium dioxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, 1,3,5-triazine-2,4,6-triamine, melamine cyanurate, melamine trithiocyanate, and symmetrical triaminotriazine. The porosity of the diaphragm is 20%-70%.

[0011] In one optional implementation, the electrode is a positive electrode or a negative electrode; The negative electrode sheet includes a negative current collector and a negative active layer located on at least one side of the surface of the negative current collector. The negative active layer includes a negative active material, which includes a silicon-carbon material. The cross-section of the silicon-carbon material has an interior angle greater than 180°.

[0012] Furthermore, based on the total mass of the negative electrode active layer, the mass percentage of silicon is 1%-50%; And / or, the particle size Dv50 of the silicon-carbon material is 5μm-16μm.

[0013] In one optional embodiment, the surface of the negative electrode active layer includes a plurality of grooves; the total area of ​​the plurality of grooves accounts for 1%-35% of the total area of ​​the surface of the negative electrode active layer, preferably 3%-30%; And / or, the width n of the groove is 10μm-220μm, preferably 20μm-200μm; And / or, the depth m of the groove is 1μm-35μm, preferably 5μm-30μm; And / or, the distance between two adjacent grooves is 500μm-2000μm.

[0014] Furthermore, 600≤(H+n)*(h+m)≤21000, preferably, 200≤H*h≤3000.

[0015] Secondly, the present invention also provides an electrical device including the battery described above.

[0016] Beneficial effects: The battery of the present invention optimizes the gap structure between the separator and the electrode, so that a more regular and uniform gap is formed between the separator and the electrode. This not only improves the storage capacity of the lithium battery for electrolyte, but also improves the distribution consistency of the electrolyte in the lithium battery. At the same time, it provides a fast flow channel for the electrolyte, thereby ensuring the uniformity of ion transport and dispersion, improving the interface performance between the separator and the electrode, and thus improving the cycle capacity retention rate and low-temperature discharge performance of the lithium battery. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a SEM image of the gap location in the lithium-ion battery in Embodiment 1 of the present invention.

[0019] Figure 2 This is a structural schematic diagram of the gap position in an embodiment of the present invention. Figure 1 .

[0020] Figure 3 This is a structural schematic diagram of the gap position in an embodiment of the present invention. Figure 2 .

[0021] Figure 4 This is a structural schematic diagram of the gap position in an embodiment of the present invention. Figure 3 .

[0022] Figure 5 This is a structural schematic diagram of the gap position in an embodiment of the present invention. Figure 4 .

[0023] Figure 6 This is a SEM image of the silicon-carbon material, the negative electrode active material, in an embodiment of the present invention.

[0024] Figure label: 1-Carrier layer, 2-Adhesive dots, 3-Negative electrode sheet, 4-Groove. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The embodiments of the present invention are described below in conjunction with the above-described scheme.

[0027] According to an embodiment of the present invention, in one aspect, a battery is provided, comprising an electrode, a separator, and an electrolyte. The separator comprises a carrier layer and a coating disposed on at least one surface of the carrier layer. The coating comprises a plurality of adhesive dots. The adhesive dots are located between the carrier layer and the electrode, and there is a gap between the electrode and the carrier layer located between two adjacent adhesive dots. The length of the gap is H μm, and the width of the gap is h μm. Along the thickness direction of the diaphragm, several cross sections are taken between the electrode and the diaphragm; in the cross sections, the difference between the maximum and minimum values ​​of the gap length H is less than or equal to 1000 μm, the difference between the maximum and minimum values ​​of the gap width h is less than or equal to 5 μm, and the number of the cross sections is greater than or equal to 5.

[0028] When taking cross-sections, the cutting angle is not limited, as long as the cross-section is taken along the thickness direction of the separator; the number of cross-sections is greater than or equal to 5. In this invention, there is a gap between the separator and the electrode. Arbitrarily cut several cross-sections (e.g., 10 cross-sections, specifically 5 along the length of the electrode and 5 along the width of the electrode) at the point where the separator and electrode are attached in the lithium-ion battery. The gap on the cross-sections can be seen using an optical microscope. Figure 1 As shown.

[0029] In this invention, the separator includes a carrier layer and a coating disposed on at least one side of the carrier layer. The coating includes a plurality of adhesive dots located between the carrier layer and the electrode. A gap exists between adjacent adhesive dots between the electrode and the carrier layer; that is, the gap is formed by the separator carrier layer, the adhesive dots on the carrier layer, and the electrode. Research has found that if the separator and electrode are too tightly bonded (without gaps), the electrolyte penetration resistance is high, leading to insufficient electrolyte wetting and the risk of lithium plating at the interface. In this invention, the adhesive dots partially support the separator, forming a gap between the separator and the electrode. This gap provides a rapid flow channel for the electrolyte, effectively suppressing the DCIR growth rate and preventing premature battery degradation due to excessive polarization, thus affecting the battery's cycle performance. Simultaneously, the gap significantly reduces the electrolyte flow resistance at the separator-electrode interface. During low-temperature, high-current discharge, the electrolyte reserve in the gap can quickly replenish the lithium ions consumed on the electrode surface, alleviating concentration polarization caused by ion transport lag, thereby improving the battery's low-temperature discharge performance.

[0030] In several cross sections, the smaller the difference in gap width h, the higher the consistency of gap width, the more uniform the electrolyte distribution, and the better the consistency of ion transport. Conversely, the larger the difference in gap width h, the worse the thickness compression consistency of the adhesive dots, the more uneven the spatial distribution inside the cell, and the more uneven the electrolyte distribution, which will lead to a decrease in the consistency of ion transport inside the battery. Therefore, in this invention, the difference in gap width h in the cross sections is controlled within a range of less than or equal to 5 μm to improve the consistency of gap width in the cross sections, thereby improving the consistency of electrolyte distribution inside the battery and improving the consistency of ion transport.

[0031] In several cross-sections, the larger the difference between the maximum and minimum values ​​of the gap length H, the greater the difference in distance between adjacent adhesive dots on the carrier layer, the more uneven the distribution of adhesive dots, the higher the difference in adhesive dots within different unit areas, the lower the coverage of adhesive dots on the carrier layer, the weaker the adhesion between the electrode and the separator, the more internal side reactions occur in the cell under high-temperature conditions, and the higher the DCIR growth rate. Conversely, the smaller the difference, the smaller the distance difference between adhesive dots on the carrier layer, the more uniform the distribution of adhesive dots, the stronger the adhesion between the electrode and the separator, the fewer internal side reactions occur in the cell under high-temperature conditions, and the lower the DCIR growth rate. Therefore, in the cross-sections of this invention, controlling the difference in the gap length H within the range of less than or equal to 1000 μm can ensure uniform distribution of adhesive dots on the carrier layer, guarantee the adhesion between the electrode and the separator, reduce internal side reactions in the battery, reduce the rate of decay of the battery's cycle capacity retention, and improve the low-temperature discharge performance of the lithium battery.

[0032] In summary, by creating a gap between the separator and the electrode, and by comprehensively controlling the difference between the maximum and minimum values ​​of the gap length H and the gap width h in the cross-section, a gap of uniform size can be formed between the separator and the electrode. This improves the electrolyte retention level of the battery, provides a rapid flow channel for the electrolyte during battery cycling, and reduces the DCIR growth rate of the lithium battery under high-temperature cycling and storage conditions. This slows down the rate of decrease in battery cycle capacity retention and improves the low-temperature discharge performance of the lithium battery.

[0033] As an example, the difference between the maximum and minimum values ​​of the gap length H in the cross section can be 10μm, 20μm, 50μm, 80μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, or within any two of the above values; the difference between the maximum and minimum values ​​of the gap width h in the cross section can be 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, or within any two of the above values.

[0034] In one optional embodiment, the length H of the gap in the cross-section is 50μm-1200μm, preferably 150μm-800μm. The value of the length H of the gap in the cross-section is related to the distribution of adhesive dots on the membrane carrier layer. When spraying, the distance between two adjacent adhesive dots can usually be controlled between 50μm-1200μm, preferably between 150μm-800μm. If the adhesive dots are set by dotting, the distance between adjacent adhesive dots can generally be preferably controlled between 50μm-200μm.

[0035] This invention can adjust the coverage of adhesive dots on the diaphragm by controlling the length H of the gap in the cross section. When the length H of the gap is in the range of 50μm-1200μm, the coverage of adhesive dots on the carrier layer can be controlled to reach 10%-30%. Within this coverage range, the adhesion between the diaphragm and the electrode can be ensured by hot pressing, which is also beneficial to increasing the electrolyte retention and improving ion transport performance.

[0036] As an example, the length H of the gap in the cross section can be 50μm, 80μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, 1100μm, 1200μm or within any two of the above values.

[0037] In one optional embodiment, the width h of the gap in the cross-section is 0.5μm-8μm, preferably 1μm-4μm. The value of the gap width h is related to the height and diameter of the adhesive dots and the hot pressing process in the cell manufacturing process (for example, the width h can be adjusted by adjusting any one or more parameters of the hot pressing temperature, hot pressing pressure, and hot pressing time, especially the hot pressing pressure). By controlling the hot pressing conditions and the height and size of the adhesive dots, the h value can be controlled within the range of 0.5μm-8μm, ensuring that the cell hardness is qualified, while providing sufficient gaps to improve the ability to store electrolyte. Furthermore, the h range is preferably 1μm-4μm. Within this preferred range, the adhesion between the adhesive layer and the electrode is moderate and does not damage the surface morphology of the electrode, better delaying the rate of decrease in battery cycle capacity retention and improving the low-temperature discharge performance of the lithium battery. If the gap width is too small, the liquid storage space formed between the separator and the electrode is insufficient, which leads to the interruption of the lithium-ion transport path in the later stages of battery cycling, causing a sharp increase in the battery's internal resistance and affecting the battery's cycle life and low-temperature discharge performance. If the gap width is too large, the adhesive dots and the electrode cannot form a good bond and fixation. Under the expansion and contraction stress of long-term cycling, it may lead to interface delamination. After delamination, the electrode and separator lose their tight adhesion, the ion transport path is broken, and the risk of local lithium plating increases sharply. At the same time, an excessively large gap reduces the battery's volumetric energy density.

[0038] As an example, in the cross-section, the width h of the gap can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, or within any two of the above values.

[0039] Furthermore, in the cross section, the difference between the maximum and minimum values ​​of the gap length H is 10-1000 μm, and / or the difference between the maximum and minimum values ​​of the gap width h is 0.1 μm-5 μm, preferably 0.1 μm-2 μm.

[0040] The length H and width h of the gap in the cross-section are obtained by the following detection method: a. Cut out a sample of appropriate size, paste it onto aluminum foil and wrap it, then use a glass slide to clamp and flatten the wrapped sample; b. Install the flattened sample onto the sample holder and adjust the extension height appropriately; c. Place the sample clamp into the sample chamber, close the instrument door, and evacuate the vacuum. d. Set the cutting time, voltage, and beam current parameters of the argon ion mill, and the equipment will automatically perform ion cutting; e. After cutting, remove the sample and take pictures and measure it using an electron microscope. A schematic diagram of the photographic results is shown below. Figure 1 As shown.

[0041] It should be noted that during sample preparation, the positive electrode, negative electrode, and the separator between the electrodes are prepared as a whole; that is, the sample includes the positive electrode, negative electrode, and the separator between the electrodes. The testing instrument can be a Hitachi SU5000 optical microscope; the argon ion grinder can be an IM4000 PLUS.

[0042] In one optional implementation, the area of ​​the gap is S μm. 2 S≥150, preferably, the value of S is 150-2000, more preferably 250-2000.

[0043] As an example, the value of S can be 150, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2500, 3000, or within any two of the above values.

[0044] The area S of the gap can be obtained by combining a cross-sectional image taken by an electron microscope with graphic analysis software (e.g., ImageJ); or by calculation, where: S=H*h.

[0045] In one optional embodiment, the adhesive dots comprise polymer particles with an average diameter of 10 μm to 1500 μm. If the diameter of the adhesive dots is too large, the coverage of the dots on the carrier layer will be too high, increasing the membrane permeability and thus the battery's DCIR value. If the diameter of the adhesive dots is too small, the coverage of the dots on the carrier layer will be too low, weakening the adhesion between the membrane and the electrode, increasing the unevenness of electrolyte distribution, and leading to rapid capacity retention decay during cell cycling. This invention, by coordinating the diameter of the adhesive dots with the length H and width h of the gap, can control the coverage of the adhesive dots on the membrane to 10%-30%. At this coverage level, it can ensure the battery's electrolyte retention while reducing the interfacial impedance, effectively improving the cell's high-temperature long-cycle performance and low-temperature discharge performance.

[0046] As an example, the average diameter of the adhesive dots can be 10μm, 30μm, 50μm, 80μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, 1100μm, 1200μm, 1300μm, 1400μm, 1500μm, or within any two of the above values; the coverage of the adhesive dots on the carrier layer can be controlled to be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or within any two of the above values.

[0047] Furthermore, the average particle size of the polymer particles is 0.1 μm - 0.5 μm. The polymer particles are selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride, modified polyvinylidene fluoride-hexafluoropropylene and its copolymers, polyimide, polyacrylonitrile, polymethyl methacrylate, and polyacrylic acid.

[0048] As an example, the average particle size of the polymer particles may be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, or within any two of the above values.

[0049] The diameter of the adhesive dots was determined using the following method: Select a test sample with dimensions of 100mm x 100mm arbitrarily on the diaphragm. Under a scanning electron microscope or a 3D optical microscope, randomly select multiple test areas (e.g., 5 areas) and read the diameter of each test dot in each test area at a certain magnification (e.g., 500x or higher). Count the number of test dots and their diameters in each test area, and take the arithmetic mean of the diameters of all test dots in each test area as the average diameter of the particle being tested. To ensure the accuracy of the test results, multiple test samples (e.g., 10 samples) can be used for the above test, and the average value of each test sample can be taken as the final test result. The testing instrument can be a Hitachi SU5000 optical microscope. It should be noted that when the test dot is irregularly shaped, the distance between the two farthest points on the test dot should be taken as the diameter of the dot.

[0050] The average particle size of the polymer particles was tested using the same method as the diameter of the adhesive dots described above. The test was conducted using a scanning electron microscope with the local magnification of the diaphragm adjusted to 1000x or higher.

[0051] Furthermore, if the average diameter of the adhesive dots is too small, the adhesion between the separator and the electrode is weak, and the battery is prone to cycle failure during cycling. In this invention, the average diameter of the adhesive dots is preferably 100μm-1000μm.

[0052] In one optional embodiment, the porosity of the separator is 20%-70%. Excessive porosity of the separator increases battery self-discharge, exacerbates capacity loss, shortens battery cycle life and calendar life, and may increase the safety risk of lithium plating due to localized over-discharge, adversely affecting the long-term stable use of the battery. Conversely, insufficient porosity of the separator results in high DCIR of the battery, significantly increasing heat generation during cycling, leading to accelerated internal temperature rise and significantly reducing battery safety and reliability.

[0053] As an example, the porosity of the membrane can be 20%, 30%, 40%, 50%, 60%, 70%, or within any two of the above values.

[0054] The porosity of the carrier layer was calculated using the following method: Cut the diaphragm sample into circular pieces with a diameter ≥25mm and dry them in a vacuum drying oven at 80℃ for more than 2 hours. After cooling to room temperature, weigh them accurately (m1). Then, completely immerse the sample in anhydrous n-butanol and apply a vacuum (-0.095MPa) for 30 minutes to ensure that the diaphragm pores are completely filled with liquid. Then, remove the sample, gently press both sides with filter paper, and weigh the particles (m2). Given that the density of n-butanol at room temperature is 0.0810g / cm³ and the density of the diaphragm material PE is 0.94~0.97g / cm³, calculate the pore volume = (m2-m1) / n-butanol density; the carrier volume = m1 / PE density, or can be calculated by thickness × surface area; the total sample volume = pore volume + diaphragm volume; the porosity = pore volume / total sample volume × 100%.

[0055] Furthermore, the carrier layer includes a substrate layer, or the carrier layer includes a substrate layer and a heat-resistant layer disposed on the substrate layer; the substrate layer is a polyolefin porous base membrane, and the material of the substrate layer is one or more of polyethylene, polypropylene, or polyethylene-polypropylene composite material; the heat-resistant layer includes heat-resistant particles, and the material of the heat-resistant particles is one or more of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon dioxide, tin dioxide, titanium dioxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, 1,3,5-triazine-2,4,6-triamine, melamine cyanurate, melamine trithiocyanate, and symmetrical triaminotriazine.

[0056] In one alternative embodiment, the electrode is a positive electrode or a negative electrode; the gap may be formed between the positive electrode and the separator or between the negative electrode and the separator.

[0057] In one optional embodiment, the negative electrode sheet includes a negative current collector and a negative active layer located on at least one side surface of the negative current collector. The negative active layer includes a negative active material, which is a silicon-carbon material. The cross-section of the silicon-carbon material has an interior angle greater than 180°. Figure 6 As shown.

[0058] During battery charging and discharging, the negative electrode active material undergoes significant volume expansion, especially for silicon-carbon materials. When the electrode expands, it compresses the separator, leading to a decrease in separator porosity or deformation. In this invention, the cross-section of the negative electrode silicon-carbon material has an interior angle greater than 180°. This silicon-carbon composite material is a spherical silicon with a grooved structure on its surface, which enhances the contact area and adhesion between particles in the negative electrode, improving the electrode's dynamic performance. Simultaneously, this morphology of the silicon-carbon material can uniformly disperse expansion stress in all directions, avoiding stress concentration that could lead to silicon-carbon material cracking and failure. The dispersion of expansion stress also prevents increased impedance caused by interfacial compression deformation due to localized stress concentration. This silicon-carbon material, combined with the uniform gap formed between the separator and the negative electrode, compresses the gap when the electrode expands, preventing direct compression of the separator and reducing the impact of electrode expansion on the separator. Furthermore, even in the expanded state, the electrode surface still retains space for electrolyte flow, ensuring a stable transport path for lithium ions during long cycles, synergistically improving the battery's cycle stability and low-temperature discharge capability. In this application, an interior angle refers to a straight line tangent to the contour of silicon-carbon material, drawn from the intersection of the grooves in the silicon-carbon particles in the cross-section of the material. Two distinct tangent lines exist, and the angle formed by these two lines on the silicon-carbon cross-section is denoted as an interior angle. An interior angle is as follows: Figure 6 As shown in ∠2.

[0059] Based on the total mass of the negative electrode active layer, the mass percentage of silicon element is 1%-50%, and / or the particle size Dv50 of the silicon-carbon material is 5μm-16μm.

[0060] As an example, the mass percentage of silicon can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, or within any two of the above values; the particle size Dv50 of the silicon-carbon material can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, or within any two of the above values.

[0061] Furthermore, the porosity of the negative electrode is 40%-50%. If the porosity of the negative electrode is too high, the electron transport capacity of the electrode decreases, and the DCIR of the battery increases. If the porosity of the negative electrode is too low, it reduces the electrolyte filling space and increases ion migration resistance, leading to a decrease in the ion transport capacity of the electrode and a decrease in the electrolyte storage capacity. A negative electrode within this porosity range can improve the electrolyte storage capacity and reduce the risk of lithium plating.

[0062] As an example, the porosity of the negative electrode sheet can be 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, or within any two of the above values.

[0063] The porosity of the negative electrode sheet was detected using the following method: Cut the negative electrode sheet into samples of length L and width M, measure the thickness N, and calculate the apparent volume: V1 = L × M × N; then use a true density meter to measure and calculate the true volume V2 of the sample using the principle of gas replacement, where helium inert gas can be used as the replacement medium, and the testing instrument can be AccuPyc III 1350; the porosity of the negative electrode sheet = (V1 - V2) / V1.

[0064] In one optional embodiment, the surface of the negative electrode active layer includes a plurality of grooves, and the total area of ​​the plurality of grooves accounts for 1%-35% of the total area of ​​the surface of the negative electrode active layer, preferably 3%-30%.

[0065] In this invention, grooves can be formed on the surface of the negative electrode active layer using laser wire bonding. The grooves enhance the electrode's ability to store electrolyte and act as rapid channels for lithium-ion migration, ensuring timely and uniform replenishment of lithium ions throughout the negative electrode. Simultaneously, the separator adhesive layer can be embedded in the groove structure, improving the adhesion between the negative electrode and the separator, ensuring good interfacial performance, and thus enhancing the battery's long-cycle performance. If the area of ​​the grooves on the negative electrode is too large, it significantly weakens the overall mechanical strength of the negative electrode, making it more prone to breakage or cracking during winding and rolling processes, affecting the battery's cycle performance. Excessively large grooves also reduce the battery's energy density. Conversely, if the area of ​​the grooves on the negative electrode is too small, the increase in electrolyte storage space is limited, failing to effectively guide rapid electrolyte penetration, and the improvement in cycle life is not significant.

[0066] As an example, the area of ​​the groove on the negative electrode can be 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or within any two of the above values.

[0067] Furthermore, the width of the groove is nμm, and the depth of the groove is mμm. The width n of the groove is 10μm-220μm, preferably 20μm-200μm; the depth m of the groove is 1μm-35μm, preferably 5μm-30μm, and / or the distance between two adjacent grooves is 500μm-2000μm.

[0068] As an example, the depth m of the groove can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, or within any two of the above values. The average diameter of the adhesive dots in the groove, n, can be 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, or within any two of the above values. The distance between two adjacent grooves can be 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, 1100μm, 1200μm, 1300μm, 1400μm, 1500μm, 1600μm, 1700μm, 1800μm, 1900μm, 2000μm, or within any two of the above values.

[0069] The area ratio, depth m, width n, and distance between two adjacent grooves of the groove are obtained using the following detection method: Take a grooved electrode sample and measure it on a 2.5D tester. Within a unit length L, the number of grooves is p, and the width of a single groove is q. The tester can be a ZEISS Sigma 300. Based on the above data, the area ratio of the groove is calculated as (p×q) / L; Depth m and width n detection method: Clamp the electrode in the resin sheet and cut along the vertical groove direction with a planer to obtain a smooth cross-sectional view. The depth m and width n of the groove can be tested separately under a 3D profile measuring instrument, which can be a Keyence VR-6000.

[0070] In one optional embodiment, 600 ≤ (H+n)*(h+m) ≤ 21000, preferably, 200 ≤ H*h ≤ 3000. This invention increases the internal porosity of the battery by combining the gap between the separator and the electrode with grooves, thereby improving electrolyte storage capacity. Simultaneously, the grooves interact with the separator adhesive, enhancing the adhesion between the separator and the electrode, and improving the long-cycle performance and low-temperature discharge performance of the cell. If (H+n)(h+m) < 600 μm², it means the adhesive dot gap is too small or the wire-setting groove is too narrow / shallow. The resulting composite porosity is too small, resulting in insufficient electrolyte storage volume. At the interface between the electrode and the separator, if the porosity is too small, the adhesive dots cannot be effectively embedded, and the adhesion relies solely on surface contact, leading to poor bonding performance between the electrode and the separator. If (H+n)(h+m) ≥ 21000 μm², it means the gaps and grooves are too large. Excessive gaps lead to a sharp decrease in capillary attraction, preventing the electrolyte from being effectively absorbed and retained. These gaps also lengthen the liquid-phase transport distance of lithium ions, increasing concentration polarization. Simultaneously, the adhesive dots cannot fully sink to the bottom of the grooves, failing to simultaneously contact the electrode surface and the separator, resulting in poor adhesion. Therefore, by controlling (H+n)*(h+m) within a suitable range, the electrolyte retention and electrolyte stability of the battery can be significantly improved. This allows the adhesive dots to both make good contact with the negative electrode surface and partially embed themselves in the grooves, achieving optimal adhesion, maintaining uniform interfacial pressure, avoiding localized lithium plating or current concentration, and improving the cell's long-cycle performance and low-temperature discharge performance.

[0071] As an example, the value of (H+n)*(h+m) can be 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, or fall within the range of any two of the above values.

[0072] Secondly, the present invention also provides an electrical device including the battery described above.

[0073] Electrolyte The electrolyte of the present invention includes a solvent, a lithium salt, and an additive. The types and amounts of the solvent, lithium salt, and additive are not particularly limited, and can be selected from those commonly used in the art. For example, the solvent is ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, fluoroethylene carbonate, etc., the lithium salt is lithium hexafluorophosphate (LiPF6), lithium difluorophosphate, lithium bis(fluorosulfonyl)imide (LiFSI), etc., and the additive includes vinylene carbonate (VC), ethylene sulfate (DTD), etc.

[0074] [Septum] The diaphragm of the present invention includes a carrier layer and an adhesive layer composed of adhesive dots disposed on the carrier layer. The carrier layer includes a substrate layer, or the carrier layer includes a substrate layer and a heat-resistant layer disposed on the substrate layer; the substrate layer is a polyolefin porous base membrane, and the material of the substrate layer is one or more of polyethylene, polypropylene, or polyethylene-polypropylene composite material; the heat-resistant layer includes heat-resistant particles, and the material of the heat-resistant particles is one or more of boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon dioxide, tin dioxide, titanium dioxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, 1,3,5-triazine-2,4,6-triamine, melamine cyanurate, melamine trithiocyanate, and symmetrical triaminotriazine.

[0075] The carrier layer has a porosity of 20%-70%; the adhesive dots include polymer particles with an average diameter of 10-1500 μm, and the coverage of the adhesive dots on the carrier layer is 10%-30%; the average particle size of the polymer particles is 0.1-0.5 μm; the average diameter of the adhesive dots is preferably 100 μm-1000 μm.

[0076] [Positive Electrode Tablets] The positive electrode sheet of the present invention includes a positive current collector and a positive active layer coated on one or both sides of the positive current collector. The positive active layer includes a positive active material, a conductive agent and a binder. The positive active layer includes 95.9-97.6 wt% positive active material, 1.5-2.6 wt% conductive agent and 0.9-1.5 wt% binder.

[0077] This invention does not impose any particular limitation on the positive electrode active material, which can be the conventional nickel-cobalt-manganese ternary positive electrode material LiNi. x Co y Mn 1-x-y O 2、 Lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, lithium manganese iron phosphate, etc. This invention does not impose any particular limitation on the conductive agent in the positive electrode sheet; it can be selected from conductive agents conventionally used in the art, including but not limited to one or more of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes, and metal powder.

[0078] The present invention does not impose any particular limitation on the binder in the positive electrode sheet, which may be selected from binders commonly used in the art, including but not limited to one or more of styrene-butadiene rubber latex, polytetrafluoroethylene latex, sodium carboxymethyl cellulose, sodium alginate, polyvinyl alcohol, polyacrylic acid, lithium polyacrylate, sodium polyacrylate, carboxylated chitosan, and polyvinylidene fluoride.

[0079] In the positive electrode sheet of the present invention, under the same positive electrode active material composition, the content and type of positive electrode active material, binder and thickener within the above-mentioned proportion range have no significant effect on the effect, and the content and type of conductive agent and binder will not be verified in subsequent embodiments.

[0080] Negative electrode plate The negative electrode sheet of the present invention includes a negative electrode current collector and a negative electrode active layer coated on one or both sides of the negative electrode current collector.

[0081] The negative electrode active layer includes a negative electrode active material, a conductive agent, a binder, and a thickener. The negative electrode active material can be a conventional carbon negative electrode active material such as artificial graphite, or a silicon-based negative electrode active material, such as silicon-carbon materials, silicon-oxygen materials, elemental silicon, silicon alloys, etc.

[0082] This invention does not impose any particular limitation on the types of conductive agents, binders, and thickeners in the negative electrode sheet. The selection range can be referenced to the types of conductive agents and binders in the positive electrode sheet. For example, the binders include styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyacrylic acid (PAA), polyisobutylene (PIB), polyimide (PI), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and vinylidene fluoride. Tetrafluoroethylene One or more of propylene terpolymer and polymethyl methacrylate (PMMA); and / or, the conductive agent includes one or more of carbon nanotubes (CNT), Ketjen black (KB), mesophase carbon microspheres, vapor-deposited carbon fiber (VGCF), conductive carbon black (SP), conductive graphite, and acetylene black (AB); preferably, the conductive agent includes conductive carbon black and carbon nanotubes, the binder includes polyacrylic acid (PAA) and styrene-butadiene rubber (SBR), and the thickener includes carboxymethyl cellulose (CMC).

[0083] According to an embodiment of the present invention, in another aspect, the present invention also provides an electrical device including the battery described above.

[0084] The lithium-ion battery provided by the present invention will be further described in detail below through specific embodiments.

[0085] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0086] Example 1 A lithium-ion battery, the specific manufacturing process of which is as follows: 1. Preparation of positive electrode sheet: Lithium iron phosphate (LFP) positive electrode material, polyvinylidene fluoride (PVDF) binder, and acetylene black conductive agent are mixed in a weight ratio of 96.5:2:1.5. N-methylpyrrolidone (NMP) is added and the mixture is stirred under vacuum until the mixture becomes a uniform and fluid positive electrode slurry. The positive electrode slurry is uniformly coated onto an aluminum foil current collector. The coated aluminum foil is baked in ovens at different temperature gradients and then dried in an oven at 100°C for 8 hours. Finally, it is rolled and slit to obtain the desired positive electrode sheet.

[0087] 2. Preparation of negative electrode sheet: The negative electrode active material artificial graphite, the thickener sodium carboxymethyl cellulose (CMC-Na), the binder styrene-butadiene rubber, the conductive agent acetylene black, and the conductive agent single-walled carbon nanotubes (SWCNT) are mixed in a weight ratio of 95.9:1:2:1:0.1, deionized water is added, and a negative electrode slurry is obtained under the action of a vacuum stirrer; the negative electrode slurry is uniformly coated on a copper foil current collector; the negative electrode sheet is obtained by drying in an oven at 85℃ for 5 hours, rolling and die cutting.

[0088] 3. Preparation of electrolyte: In a reaction vessel filled with argon and with qualified water and oxygen content, ethylene carbonate (EC), dimethyl carbonate, ethyl methyl carbonate (EMC), ethyl propionate (EP), vinylene carbonate (VC), and ethylene sulfate (DTD) are mixed evenly in a mass ratio of 24.15:24.15:32.2:2:1. Then, 0.5% lithium difluorophosphate, 6.0% lithium bis(fluorosulfonyl)imide (LiFSI), and 10% lithium hexafluorophosphate (LiPF6) are added and stirred evenly to prepare the electrolyte.

[0089] 4. Separator: A 9μm thick polyethylene base film is prepared, and then a 2μm thick alumina coating is coated on one side of the base film to prepare a carrier layer 1 with a porosity of 50%. Polyvinylidene fluoride resin is then applied to the surface of the carrier layer 1 by dispensing. After drying and slitting, a finished separator with regularly arranged adhesive dots 2 is obtained. The surface density of the adhesive coating on one side is controlled at 0.8g / ㎡, and the initial adhesive height is 5μm. Separators with different distances of adhesive dots in different directions are prepared. In this embodiment, the average diameter of the adhesive dots is 1000μm, and the distance between the adhesive dots ranges from 50 to 150 μm. 5. Battery fabrication: The positive electrode sheet, negative electrode sheet 3, and separator obtained above are stacked in the order of positive electrode sheet, separator, and negative electrode sheet, and then wound to obtain a cell assembly; the cell assembly is hot-pressed at 90°C with a hot pressing pressure of 2.5 MPa for 45s to obtain a cell assembly with a length H ranging from 50μm to 150μm and a width h of 2.1μm to 2.4μm gap. The coverage rate of adhesive dots on the carrier layer in the cell assembly is 30%. The cell assembly is placed in an outer packaging aluminum foil, and the electrolyte prepared in step 4 is injected into the outer packaging. After vacuum sealing, standing, formation, degassing and forming, sorting and other processes, a lithium-ion battery is obtained.

[0090] Examples 2-12 and Comparative Example 1 The difference between Embodiments 2-12 of the present invention and Embodiment 1 above is that the preparation of the diaphragm is different. The specific parameters of the diaphragm are shown in Table 1 below.

[0091] Table 1

[0092] In Examples 2-7 above, the gap length H is changed by altering the dispensing distance; in Examples 8-12 above, the hot pressing pressure in the battery preparation step is changed, thereby changing the final dispensing height and causing a change in the gap width h. For example, in Examples 8-12, the hot pressing pressure is adjusted to 1 MPa, 2 MPa, 3 MPa, 4 MPa, and 7 MPa in sequence; the other parameters of the above examples and comparative examples are exactly the same as those of Example 1.

[0093] Examples 13-14 and Comparative Example 2 The difference between the embodiments and comparative examples of the present invention and the above-described embodiment 1 is that the preparation of the diaphragm is different; in this embodiment, the adhesive dots in the diaphragm are applied to the carrier layer by spraying / rolling to deposit polyvinylidene fluoride resin.

[0094] The differences in diaphragm parameters between Examples 13-14 and Comparative Example 2 are shown in Table 2 below.

[0095] Table 2

[0096] In the above embodiments and comparative examples, since spraying / roller coating is used, the initial glue dot height is not a fixed value but a range. In Example 13, the initial glue dot height ranges from 1 μm to 5 μm, and the battery preparation step uses a hot-pressing pressure of 3 MPa; in Example 14, the initial glue dot height ranges from 1 to 8 μm, and the battery preparation step uses a hot-pressing pressure of 1 MPa; in Comparative Example 2, the initial glue dot height ranges from 1 to 8 μm, and the battery preparation step uses a hot-pressing pressure of 0.4 MPa; other parameters in the above embodiments and comparative examples are exactly the same as in Example 1.

[0097] Examples 15-26 The difference between this embodiment and Embodiment 10 is that the preparation of the negative electrode sheet is different; in this embodiment, the negative electrode sheet is further provided with a groove 4, such as... Figures 2-5 As shown in Table 3, the parameter settings for the grooves in different embodiments are as follows.

[0098] Table 3

[0099] The other parameters of the above embodiments are exactly the same as those of Embodiment 10.

[0100] Example 27 The difference between the embodiments of the present invention and the above-described embodiment 10 is that the artificial graphite in the negative electrode sheet uses 90.9% artificial graphite and 5% of [other materials]. Figure 6 The spherical silicon-carbon material with an interior angle greater than 180° is replaced, otherwise it is the same as in Example 10.

[0101] Example 28 The difference between the embodiments of the present invention and the above-described embodiment 27 is that the silicon-carbon material in the negative electrode is replaced by blocky silicon-carbon with an inner angle of less than 180°, while the rest is the same as in embodiment 27.

[0102] Experimental Example The batteries prepared in the examples and comparative examples were subjected to cold start tests and 45°C cycle tests. The specific test procedures are as follows: 1. Cold start test The cells from the above embodiments and comparative examples were placed in an environment of (25±2)℃ for 30 min, and then discharged with a constant current of 1C for 30 min to obtain 50% SOC; the cells were then placed in an environment of (-30±2)℃ for 4 h to reach thermal equilibrium; a constant current of 10C was used for 10 s discharge; the voltage after 10 s discharge of the cell was recorded, which is the voltage (V) after 10 s in the table below.

[0103] 2. 45℃ Cyclic Test The batteries corresponding to the above embodiments and comparative examples were placed in an environment of (45±2)℃ and left to stand for 2 hours. After 3 hours, when the battery body reaches (45±2)℃, the battery is charged at a constant current of 1C to the upper limit voltage of 3.65V and the cutoff current is 0.05C. After the battery is fully charged, it is left to stand for 5 minutes, and then discharged at a constant current of 1C to the lower cutoff voltage of 2.2V. The highest discharge capacity of the first 3 cycles is recorded as the initial capacity Q, and the initial low temperature discharge voltage data U1 of the battery is tested. When the number of cycles reaches 600, the discharge capacity Q1 of the battery at 600 cycles is recorded, and the capacity retention rate (%) = Q1 / Q×100%. Then the low temperature discharge voltage data U2 of the battery at 600 cycles is tested. When the number of cycles reaches 1200, the discharge capacity Q2 of the battery at 1200 cycles is recorded, and the capacity retention rate (%) = Q2 / Q×100%. Then the low temperature discharge voltage data U3 of the battery at 600 cycles is tested. Then the cycle capacity retention rate and low temperature discharge voltage data of each group are statistically analyzed.

[0104] The verification results of the above experiments are shown in Tables 4-6 below.

[0105] Table 4

[0106] Table 5

[0107] Table 6

[0108] As shown in Tables 4 and 5 above, by comparing Examples 1-12 with Comparative Example 1, and Examples 13-14 with Comparative Example 2, it can be seen that controlling the difference between the maximum and minimum values ​​of the gap length H is less than or equal to 1000 μm, and the difference between the maximum and minimum values ​​of the gap width h is less than or equal to 5 μm. This allows for the formation of a more regular gap between the separator and the electrode, which not only improves the lithium battery's capacity to store electrolyte, but also improves the consistency of electrolyte distribution in the lithium battery, thereby ensuring the uniformity of ion transport and dispersion, improving the negative electrode interface, and thus improving the lithium battery's cycle capacity retention rate and low-temperature discharge performance.

[0109] As shown in Table 6 above, by further adding grooves to the electrode, the electrode's ability to store electrolyte can be improved. The separator adhesive layer can be embedded in the groove structure to improve adhesion, thereby improving the battery's long-cycle performance.

[0110] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery comprising electrodes, a separator, and an electrolyte, characterized in that, The diaphragm includes a carrier layer and a coating disposed on at least one surface of the carrier layer. The coating includes a plurality of adhesive dots. The adhesive dots are located between the carrier layer and the electrode. There is a gap between the electrode and the carrier layer between two adjacent adhesive dots. The length of the gap is H μm and the width of the gap is h μm. Along the thickness direction of the diaphragm, several cross sections are taken between the electrode and the diaphragm; in the cross sections, the difference between the maximum and minimum values ​​of the gap length H is less than or equal to 1000 μm, the difference between the maximum and minimum values ​​of the gap width h is less than or equal to 5 μm, and the number of the cross sections is greater than or equal to 5.

2. The battery according to claim 1, characterized in that, In the cross section, the length H of the gap is 50μm-1200μm, preferably 150μm-800μm; And / or, the width h of the gap is 0.5μm-8μm, preferably 1μm-4μm; And / or, the area of ​​the gap is 150 μm. 2 -2000μm 2 Preferably 250μm 2 -2000μm 2 .

3. The battery according to claim 1 or 2, characterized in that, In the cross-section, the difference between the maximum and minimum values ​​of the gap length H is 10 μm-1000 μm. And / or, in the cross section, the difference between the maximum and minimum values ​​of the gap width h is 0.1 μm-5 μm, preferably 0.1 μm-2 μm.

4. The battery according to any one of claims 1-3, characterized in that, The adhesive dots comprise polymer particles, and the average diameter of the adhesive dots is 10μm-1500μm; And / or, the coverage of the adhesive dots on the carrier layer is 10%-30%.

5. The battery according to claim 4, characterized in that, The average particle size of the polymer particles is 0.1 μm-0.5 μm; And / or, the average diameter of the adhesive dots is 100μm-1000μm; And / or, the polymer particles are selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride, modified polyvinylidene fluoride-hexafluoropropylene and its copolymers, polyimide, polyacrylonitrile, polymethyl methacrylate, and polyacrylic acid.

6. The battery according to any one of claims 1-5, characterized in that, The carrier layer includes a substrate layer, or the carrier layer includes a substrate layer and a heat-resistant layer disposed on the substrate layer; The substrate layer is a polyolefin porous base membrane, and the material of the substrate layer is one or more of polyethylene, polypropylene, or polyethylene-polypropylene composite material; The heat-resistant layer includes heat-resistant particles, which are made of one or more of the following materials: boehmite, alumina, barium sulfate, magnesium oxide, magnesium hydroxide, silicon dioxide, tin dioxide, titanium dioxide, calcium oxide, zinc oxide, zirconium oxide, yttrium oxide, nickel oxide, cerium oxide, zirconium titanate, barium titanate, magnesium fluoride, 1,3,5-triazine-2,4,6-triamine, melamine cyanurate, melamine trithiocyanate, and symmetrical triaminotriazine. The porosity of the diaphragm is 20%-70%.

7. The battery according to any one of claims 1-6, characterized in that, The electrode is either a positive electrode or a negative electrode; The negative electrode sheet includes a negative current collector and a negative active layer located on at least one side of the surface of the negative current collector. The negative active layer includes a negative active material, which includes a silicon-carbon material. The cross-section of the silicon-carbon material has an interior angle greater than 180°.

8. The battery according to claim 7, characterized in that, Based on the total mass of the negative electrode active layer, the mass percentage of silicon is 1%-50%; And / or, the particle size Dv50 of the silicon-carbon material is 5μm-16μm.

9. The battery according to claim 7, characterized in that, The surface of the negative electrode active layer includes a plurality of grooves; the total area of ​​the plurality of grooves accounts for 1%-35% of the total area of ​​the surface of the negative electrode active layer, preferably 3%-30%; And / or, the width n of the groove is 10μm-220μm, preferably 20μm-200μm; And / or, the depth m of the groove is 1μm-35μm, preferably 5μm-30μm; And / or, the distance between two adjacent grooves is 500μm-2000μm.

10. The battery according to claim 9, characterized in that, 600≤(H+n)*(h+m)≤21000, preferably, 200≤H*h≤3000.

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